Assembling the iDevice Guitar Interface
Update: 10/19/2011, added links to part #s at radioshack, mouser and mammoth.
Here’s the exciting conclusion to the series, following up the intro in Part 1, and the electronics course in Part 2.
The main goal here is to cram all the parts into the narrow confines of the jack, so we don’t need to use an external box or enclosure.
In addition to the cable and jack parts listed in Part 1, here are some of the things you’ll need:
- the schematic discussed in Part 2
- MPF102 JFET transistor
- Radio Shack part #276-2062
- Mouser part #512-MPF102
- Pedal Parts Plus part #4008
- Mammoth Electronics part #mpf102
- a couple zener diodes, 5v or 6v breakdown voltage (e.g. 1N4773A, 1N4734A, 1N4735A, or NTE1354A, NTE136A, etc)
- Radio Shack part #276-0565
- Mouser part #512-1N4733A
- Mammoth Electronics part # 1n4733
- some 1/4W or 1/8W resistors: 1.2k (brown red red), 10k (brown black orange), and 1M (brown black green)
- Mouser 271-1.2K-RC, 2710-10K-RC, 271-1.0M-RC
- Mammoth Electronics resistors 10-271-1.2K-RC, 110-271-10K-RC and 110-271-1.0M-RC
And some tools:
- a soldering iron. I use the Weller WES51 at 750 degrees
- some 60/40 rosin core solder
- Helping hands or a pair of locking pliers
- wire cutters and stripper
- needle nose pliers
- various sizes of heat shrink (I use 3/8” and 1/8” in the video)
- a multimeter to check your work. I use the Mastech MS8229
- a bit of 24 gauge PVC coated tinned wire
- a magnifying glass and a good light so you can see what you’re doing!
- steady hands!
September 24, 2011 @ 9:01 pm
interesting and informative. Keep it up!
September 25, 2011 @ 5:11 am
there isn’t any amp modeling app for Android devices like my Galaxy Tab but
I hope someday they will come with something. Just a question. Can I build
a similar device for a mic computer jack (taking in consideration that the
jack is only tip/ring/sleeve and not tip/ring/ring/sleeve as you us here)?
September 24, 2011 @ 11:15 pm
Great tutorial, tx!
A little question a bit out of topic: my old imac late 2006 have a audio-in stereo minijack that is an Line-In. If accidentally i’ve not an audio interface, a d.i. or a pedal effect, or an amp with me, exist a simple cable mod to solve the impedance mismatch? I ask it because the audio-in have not a DC preamp on it and i don’t know if your suggested mod can accomplish the same good work in this case. :’)
September 25, 2011 @ 11:39 am
Since a line-in provides no power, you would have to provide your own power source (a battery) for a JFET preamp. And the circuit will be a little different. I may do a how-to on that at some point 🙂
-John
October 25, 2013 @ 6:09 pm
In fact, most macbook work with iphone headset ( they have mic input in the same jack) so you can use this circuit with your macbook. It work with mine, a 2009 thought so first try a iphone headset with your mac to see if the mic work.
September 25, 2011 @ 10:21 am
these, but I think I’m gonna have to get some helping hands. Did you say
this same thing would work on a macbook pro with only one audio
input/output port?
September 25, 2011 @ 11:46 am
September 25, 2011 @ 7:10 pm
components I needed. Can you recommend any other store or website that
might have what I need.
September 26, 2011 @ 6:32 am
Hi John,
Thank you so much for your videos! I made one last night using an old apple earphone and some components that I gathered from radioshack (It ends up costing me about $9!). It works great so far. The only thing is that it is a little noisier than I expected although I don’t know how the commercial counterpart would sound. Anything I can do to fix that? Once again thank you so much!
September 27, 2011 @ 11:44 am
Hi Jerry,
Glad to hear the build went well!
What’s the character of the noise? Are you sure it’s from your cable, and not from whatever guitar app you’re using? Amplitube’s amp models are indeed a bit noisy.
For example, how does it sound just using the headphones, and listening to some music from the iPod player app? That should sound perfect.
If you’re convinced it’s a problem in your build- does the cable have good braiding shielding? If not, you may benefit from a higher quality cable with good shields. Do you have solid ground connections? Let me know what you find!
-John
September 26, 2011 @ 5:51 pm
to be a problem isnt it.
September 27, 2011 @ 9:34 am
i found it. I did find most of the parts I needed I decided to use a male
1/4″ plug because I couldn’t find a female with room for the components. I
did manage to get it together last night and it was a little noisy i think
im going to pick up another trrs cable on ebay and see if it works right.
Also I couldn’t find a 1.2k Ohm resistor so I used a 1K would there be a
better one to use?
September 27, 2011 @ 6:26 pm
September 27, 2011 @ 8:22 pm
October 19, 2011 @ 8:09 am
PD: i used a 2N5457 JFet could that be?
October 19, 2011 @ 9:12 am
October 19, 2011 @ 1:12 pm
October 23, 2011 @ 2:58 am
October 26, 2011 @ 11:48 pm
how if i am using 2SK246 is it possible???
October 27, 2011 @ 10:48 am
The 2SK246 is a higher-voltage part. I haven’t used it, but you should be able to get it working. Check the datasheet- the pinout is different from the MPF102/2N5457/etc. Source, Gate, Drain instead of Gate, Source, Drain. You’ll probably need to experiment with the source resistor value to get it going. Let me know how it goes!
-John
November 14, 2011 @ 2:38 pm
November 15, 2011 @ 11:17 am
November 22, 2011 @ 12:45 pm
hi mr. John and tyvm for detailed diy irig project. i have little question : i bought a cable which is similar yours but first circle is ground instead of mic. if i use ground cable as mic cable would it be a problem ? and how should i describe my problem or exact cable to my local seller ? (sorry for my bad English)
November 22, 2011 @ 12:54 pm
You have a cable with a tip-ring-ring-sleeve connector on one end, and at the other are some bare wires? You can connect the wires to your jack as described in the video.
See part 1 of this video series, where I show how to identify which wires connect to the plug rings, using a multimeter.
-John
November 23, 2011 @ 11:32 am
Thanks for response. i checked cable with multimeter and sleeve (bottom opposite of tip) shows ground. i guess original listing must have as your cable “mic,ground,right,left” but mine “ground,mic,right,left”. actually cable was designed for nokia n95 or any mp4 player. May i use this cable by changing bare wires? By the way in turkey its hard to find j201. instead of j201 i will use Bf245c. Do you have any ohm suggestion for bf245c. i don’t understand electronic staff and datasheets. i’ve browsed tons of website but your page is most clear and effective. Thanks for helps.
November 26, 2011 @ 3:12 pm
The connector and wires don’t have any inherent “ground,mic,right,left”. It’s just a connector with 4 wires attached to the rings.
Just do as I showed in part 1 of this video series here: https://www.planetz.com/?p=1510 .
Using a multimeter, write down which wire connects with each of the rings. Then, hook them up to your circuit, according to the iphone/ipad pinout requirements.
For BF245, note the pins are in a different order from the MPF102. GSD instead of DSG. Also, the BF245 A,B,C parts have a narrower IDSS range, so be prepared to experiment with the source resistor to find a good value.
John
November 27, 2011 @ 10:57 am
Thanks,thanks,thanks. 🙂 i did custom 3,5mm trrs male jack because second ring wasn’t linked to ground. and bf245c source with 1.2 k ohm working well but lil’bit noisy. Thank you very much for this project and helps.
March 24, 2012 @ 11:16 am
thanks a lot man. i build this preamp with BF245C. i try different source rezistors and if found the sound is clean on 100ohm. hope is helpfull..
March 24, 2012 @ 10:45 pm
Thanks for the info!
John
April 6, 2012 @ 3:04 pm
I have the same cable as you ( ground white yellow red )
I couldn’t get it to work, so how did you do made this with that cable??!!
April 6, 2012 @ 3:46 pm
Follow the steps I show in part 1 of the video to confirm which wire colors connect to the tip, rings and sleeve.
John
November 22, 2011 @ 11:23 pm
Hello there,
Can I use this idea on my Dell Laptop with bass guitar (without any extra modification on the circuit/component)?
November 26, 2011 @ 10:47 am
Should work, if it’s a mic input (not line input). For more details, see my reply above to horestra on September 25.
-John
November 26, 2011 @ 3:24 pm
Oh okay..Thanks mate!
November 23, 2011 @ 1:24 am
Hello there,
Almost all electronics retail has no JFET MPF102 (I don’t why!!!).
Is there any alternative JFET that I can replace?
November 26, 2011 @ 10:52 am
My local Radioshack and Frys stores carry it. If you can’t find it locally, you can order online at any number of places- I linked to the mpf102 at a few vendors in my original post (radioshack, mouser, pedal parts plus, mammoth).
I also listed some alternative parts in the schematic here:
https://www.planetz.com/?p=1531
-John
October 25, 2013 @ 6:13 pm
You can crack open a cheap mic, you will find the fet you need inside.
December 13, 2011 @ 11:40 pm
Hi john I am so happy to have come across your website
i was able to follow a diagram
http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=46581&g2_serialNumber=1
from diystompboxes website and was quite amazed with the results for a time.. however, it seems that after some time it didn’t work anymore. I dont know what happened, i receive “No Input” in amplitube
I observed that your diagram is quite different but uses the same mpf102.
I also have a demo vid of me using that schem at the time that it was still doing fine.. http://www.youtube.com/watch?v=sRRUiqjQLhc
This are my questions
1. Was wondering if you do encounter “No Input” problems too using amplitube?any solution?
2. Does plugging it into an amplifier (not speakers) provide something new to the system(voltage, anything else?)
THanks alot =)
December 14, 2011 @ 8:41 am
Hi Jade,
I only saw the “no input” problem when I was first experimenting with the circuit and didn’t have it wired up properly.
Plugging the headphone output into an amp shouldn’t affect the circuit. The outputs aren’t connected into the preamp at all.
It’s quite possible that a static discharge fried your JFET – a JFET’s gate is very static sensitive. This is the reason I put the zeners on the the gate input.
Do you have another JFET you can swap in to see if that solves the problem?
Another possibility is a cracked solder joint or loose wire somewhere in your circuit.
Hope this helps! Let us know what you find.
-John
December 15, 2011 @ 4:36 am
wow thanks for the reply. I fixed a new set using the same components from before with a new JFET. and tried to follow your “fit-it-all” inside the plug technique, im very amused how you did it, mine cant fit haha =D
I will be trying this one tomorrow and will be happy to report back asap =)
I haven’t tried looking for zeners yet.. but i now know why it doesn’t function anymore =D reading your posts and your reply here reminded me that on several occasions i touched the ends of the JFET using my hands. hmm, i was quite amused because while touching the JFET, the iPod played music.. touching it again caused it to fast forward… I marveled at it thinking that i might have discovered the “remote control” setting =D any thoughts on that? ^_^ thanks by the way
December 15, 2011 @ 8:54 am
Hi Jade,
If touching it fixes it, then it’s probably just a loose wire or cracked solder joint. Check all your connections with a multimeter.
Hope the new one works!
-John
December 15, 2011 @ 4:57 am
Hey John this really is a great tutorial! I was wondering, I want to plug an external mic into my idevice (iPad/iPhone). Would this circuit work for this? There are tutorials on the net that say all you need is an impedance of over 1K to get the iPhone to see the mic. But none of them mentioned the 2.8V that the iPhone is producing so this makes me a little skeptical of the tutorial. I would think that I would need to at least block the 2.8V.
My mic has a 200 Ohm impedance I am not sure what it likes to see in a preamp, maybe 2k? Thoughts?
December 15, 2011 @ 9:43 am
This JFET circuit has a very high input impedance and won’t work well with a low-impedance mic.
Here’s some other options:
– build a low-impedance preamp that can be powered by the 2.8v. Something like: http://tymkrs.tumblr.com/post/9168179996/diy-microphone-preamp
– plug your mic into a simple small mixer, and connect the output of that into the iPhone. Here’s an example:
http://metalheadreview.wordpress.com/2009/12/08/impractical-audio-recording-on-the-iphone/
– just to use a good quality electret mic (which will be powered by the 2.8v).
Hope this helps,
John
January 1, 2012 @ 5:12 am
January 5, 2012 @ 7:24 am
Can I also use this circuit to input a mic signal ( lav or shotgun) into my iphone 4?
Thanks
January 10, 2012 @ 8:52 am
A shotgun or other mic which requires phantom power will require an external preamp.
January 8, 2012 @ 4:21 pm
I followed your instructions closely, except a) I used a 1k resistor instead of 1k2 and b) ommited the 10k resistor.
My cable seems to work in Amplitube but I get a high pitch feedback if I crank up the amp’s distortion or volume. Turning my guitar’s or my loudspeakers’ volume up or down won’t affect the amount of feedback.
I tried Amplitube’s feedback suppressor but it makes my guitar sound fuzzy.
Any hints on what may have gone wrong?
Thanks
January 10, 2012 @ 8:55 am
January 16, 2012 @ 7:04 am
Hi im planning on building one of these but hoped i’d be able to use it with both guitars and mics. I was just wondering if anyone has thought about adding a switch to enable/disable the 2.8v preamp i.e. to plug a standard vocal mic in? if so would you put the switch in before all the resistors/diodes/transistor or somewhere in between? or will the cable still work fine with a mic without any modifications?
January 16, 2012 @ 4:46 pm
To use a standard electret mic, you can just plug it into the ipad, without any interface. If your mic requires phantom power, you’ll need a separate preamp.
It won’t work well to plug in a mic into this guitar interface, since a mic prefers a low impedance input, while this interface presents a very high impedance input to work well with the guitar.
John
January 17, 2012 @ 12:06 am
Thanks for the reply John, I have an iPhone 3GS which has a built in mic (not a very good one!) so whenever I plug in an external mic it seems to just default to the internal. What i meant to ask is Do you know any way of running a mic through the jack along with headphones, with fairly decent quality? I was thinking of trying a male to dual female adapter but can’t find one with the 4 contacts and not sure it would work anyway… so thought I’d be just as well trying to incorporate it into the guitar circuit or building a similar one for mic inputs. Can you suggest anything?
Thanks
January 17, 2012 @ 6:24 pm
If you use an electret/lav mic, there are no special electronics required.
You could just build a little Y cable, with the TRRS connector on one end, connecting to a mono 3.5mm female jack for the mic, and a stereo 3.5mm female jack for your headphones.
Try the Audio-Technica ATR-3350 or the Shure SM11.
-John
January 24, 2012 @ 10:10 pm
January 25, 2012 @ 8:50 am
January 28, 2012 @ 10:37 am
I just found your website and videos this morning and love them! I am heading to my local parts supplier (Norvac) to get what I can right now and try to build one of these today. I do have one question though. My main guitar has EMG pickups on it that are powered with a 9 volt battery. Would that be a reason to install zeners with a higher rating?
Thank you for the great videos and explanations! I hope to look through your other videos and build more projects!
January 28, 2012 @ 3:48 pm
I don’t have a guitar with active pickups, but I’m guessing you may not need a separate preamp.. Your guitar already has its own preamp which will likely handle the buffering that I was implementing in this circuit. I recommend you first try the experiment that I showed in part one- just wire up the jack directly and see how it works. It may be fine. If not, you can still use the circuit I showed here, and you won’t need different zeners.
Please let us know your results.
John
February 18, 2012 @ 12:53 am
Hi John, my first attempt failed due to the wrong type of cable- had shielding in it that ground edit out. Anyway, now I have the same Philmore cable you show in your videos. But when I plug it in to the headphone jack and fire up either amplitude or GarageBand, the iPads built in mic stays on and I get no input from my guitar. Any ideas on what I’m doing wrong here? I did push it in all the way, but only get mono headphone output as well.
Thank you!
February 21, 2012 @ 8:26 pm
If the ipad mic stays on, there may be a wiring issue at the jfet, or a bad jfet…
Can you try the circuit with alligator leads or breadboard to ensure all the components are working, and that you understand the circuit properly?
John
January 30, 2012 @ 8:53 pm
NICE WORK!
February 3, 2012 @ 2:43 am
hi, I’m experiencing some difficulties finding the mpf102 in Italians stores…btw I found a supplier that can sell me a MPF102_D27Z. my question is, is that jfet the same as the mpf102? any issues with the 1.2k resistor?
Just in case, which resistor should I use to get a j201 working fine in the circuit?
thank you for the great job you’ve done with the tutorial
February 5, 2012 @ 11:13 pm
Hi there,
After doing some searching- it looks like the D27Z is the same part, with a slightly different pin. From Fairchild Semiconductor, the only difference appears to be in the package description:
MPF102: 3 LD, TO92, MOLDED, STD STRAIGHT LD (NO EOL CODE)
MPF102_D27Z: 3 LD, TO92, MOLDED 0.200 IN LINE SPACING LD FORM (J61Z OPTION)
Looking those up, it just looks like one has straight pins and the other has the pins bent to fit a different hole spacing:
http://www.fairchildsemi.com/package/packageDetails.html?id=PN_TO92-F03
and
http://www.fairchildsemi.com/package/packageDetails.html?id=PN_TT92D-096
So, if I understand correctly, you should have no problem with the MPF102_D27Z
-John
February 5, 2012 @ 11:21 pm
thank you for your research.
February 4, 2012 @ 1:43 pm
February 9, 2012 @ 6:17 pm
this project is great. Im not so good at electronics so i was wondering if you could make better schematic explaining how to hook up all three of the jacks. On your schematic all I see is one input jack I think, where are the otherones?
Thanks.
February 10, 2012 @ 8:25 am
February 9, 2012 @ 7:41 pm
February 10, 2012 @ 8:30 am
February 11, 2012 @ 8:00 am
Hi John.
I’m having a blast building these things! My friends want me to build them one. I’m trying to put in a combo jack (xlr/1/4″) and I know it’ll be unbalanced, but I’m having issues with it when I put on the monitor in Garage band. when I enable monitor, volume drops considerably and signal is distorted. The other boxes I’ve built wiht 1/4″ jacks all work great. Just trying to make other input options and thought this would be good in a pinch. Let me know if you have any thoughts for wiring this config.
Great project and useful!
Thanks,
Spike.
February 11, 2012 @ 11:21 am
Hey Spike,
When you plug a 1/4″ plug into your combo jack, it should be electrically no different from the regular 1/4″ jack. If that sounds bad, then you have a wiring problem. Double check the pinout of your combo jack, and use a multimeter to confirm.
As for plugging in an XLR cable, what’s your application? It’ll have the wrong impedance for a mic. A dynamic mic might work, but there’s no phantom power here for a condenser. If you’re just wanting to use it as an unbalanced XLR interconnect with other gear, I guess it’d be ok. But remember the high-impedance input presented by the JFET!
-John
February 12, 2012 @ 6:55 pm
I just wanted to be able to plug in a dynamic mic or guitar to get stuff into the iPad. Do you have a schematic for something with phantom and/or a gain knob? Probably need a 9V or something to power it. Just askin’ because I got asked.
Thanks,
Spike.
February 12, 2012 @ 10:00 pm
Hi Spike,
Yeah, I don’t think you should try to combine those into a single interface.
Here’s a good article on JFET mic preamp with transformers:
http://www.tangible-technology.com/ipr/AE230/html/wk_6/hamptone_fet_scan.pdf
You’ll find lots of good discussion on preamps at prodigy-pro / groupdiy.
-John
February 12, 2012 @ 10:29 am
Thanks!
February 12, 2012 @ 9:01 pm
February 20, 2012 @ 4:15 am
February 21, 2012 @ 8:58 pm
Or you could put in a 50k trimpot, and adjust til it sounds good. Then measure the value of the trimpot and use a resistor close to that.
February 24, 2012 @ 9:01 pm
February 28, 2012 @ 9:40 am
February 28, 2012 @ 1:46 am
hi john, you’re tutorials are great. thankyou =)
( i’ll try this out later, anyway, will this work with a bass with an onboard active preamp? thankyou again =)
February 28, 2012 @ 8:59 am
Hi Jay,
I think you may not need something this complex, with your active preamp. See my reply to Leofric above on January 28, 2012.
Let me know how it goes for you!
John
March 4, 2012 @ 10:18 pm
First of all, awesome tutorial!
I am going to be building this and was curious as to where you purchased the 1/4 jack enclosure you used in the video? I would like to use that one instead of the Radio Shack one.
thanks,
March 4, 2012 @ 10:23 pm
Hey Don,
Sorry I forgot to link to my source for that one. I got it at Redco- their part #HJ2C:
http://www.redco.com/shopexd.asp?id=698
John
March 5, 2012 @ 9:33 am
Thanks and no apologies necessary. I eventually want to build a guitar amp and this is a nice first step in that direction. This will be first, then a headphone amp, a tube screamer clone and finally some sort of guitar amp.
Every year my students want to hear me play guitar and I hate lugging it and my Podxt around. Since I already bring my iphone every day this is a no brainer!
thanks,
Don
March 6, 2012 @ 9:53 am
Sounds like a great progression of projects.
I’m planning a video series on DIY pedal-making sometime soon- I’ll probably do a simple pedal like a treble booster, or possibly a FET boost.
-John
March 6, 2012 @ 10:56 am
I look forward to it. By then I may be ready to build mine.
March 18, 2012 @ 1:05 pm
Could you tell characteristics of the zeon diode you used?
Thanks!
March 23, 2012 @ 10:33 am
March 26, 2012 @ 7:04 am
Keep up the inspiring work!
March 29, 2012 @ 6:20 pm
Making an interface for the 30-pin dock would require becoming a licensed apple MFi developer. I don’t think it would be worth the effort unless you were planning to seriously get into iOS dock-accessory development.
John
April 5, 2012 @ 5:05 pm
John
March 26, 2012 @ 4:55 am
Have any ideea how to make an interface for ipod touch 4 for record audio from output of a audio mixer, i think i need an impedance match and an antenuator.. Sorry for my poor english..
March 29, 2012 @ 6:19 pm
This interface should work fine.
John
March 30, 2012 @ 8:01 am
Hi John. Awesome vid and guide, thanks! I’m battling to find an MPF102, 2N5457 or 2N5458 – on back order in South Africa(!) I can find a 2N5459 easily enough though. Would that work?
If so, I see the 2N5457 needed a 47k source resistor. Any ideas on what the 2N5459 would need?
March 30, 2012 @ 10:12 am
Hi Andy,
The 2n5459 should work. It’s hard (for me anyway!) to guess a resistor value from looking at the datasheet. I suggest you buy a 50k linear trimpot and use that to find a source resistor value that works. Then you can replace the trimmer with a comparable resistor.
-John
April 8, 2012 @ 7:58 am
Hi John,
Spent Easter Sunday soldering! It’s working besides two problems: noise and only the left headphones channel works (tho I suspect that is a faulty headphone jack…)
I managed to find MPF102s, but the shop had 1k8 and 1M2 resistors instead of 1k2 and 1M. I’d expect the 1M vs 1M2 doesn’t matter, but how sensitive is the source resistor value? Could it be causing the noisy signal?
Great to get the soldering kit out again. Thanks so much for this guide. I suspect this is the first of many new projects!
April 8, 2012 @ 9:41 pm
Sounds like a nice way to spend the holiday 🙂
Yes the 1M2 is fine. The 1k8 may also be ok for the source resistor, but that one is a bit more sensitive. Might be helpful to buy a bag of various resistors < 10k (or a trim pot) and experiment. What kind of noise? Like general background noise, or distortion when you play? Distortion when you play would definitely be related to the source resistor value. Bad left channel in the headphones is more likely a short than a bad jack, but anything is possible 🙂 Congrats on the build! John
April 9, 2012 @ 8:26 am
Yeah, distortion and very low volume when I play. Back to the shops for a trim pot tomorrow!
The bad left channel is weird though. iPhone audio comes through on left only too. Continuity testing is fine all the way from one end of the cable to the other. Scratching my head a bit on this. Will doubtless end up being a “duh!” issue. Will post when solved.
Will also post on the final resistor value.
-Andy
April 9, 2012 @ 8:51 am
Just checked my parts list against the store product list. My “stereo” 3.5mm jack is, um, mono. As I predicted: “Duh!” 🙂 Problem 1 solved. Now to get the right resistor. Nearly there!
Dumbass off to the shops tomorrow.
April 10, 2012 @ 8:45 am
Haha! That explains it!
Note that the trimmer will be useful for experimenting to find a good resistance value, but it won’t fit inside the jack – (not sure if you’re planning an in-the-jack build like I did, or putting the circuit inside another enclosure). In any case, once you’ve found a good value, you can check it on a multimeter, then buy a resistor that closely matches the value.
-John
June 13, 2012 @ 7:29 am
Long delayed update…
Rebuilt the assy with all the parts you used (rtfm) except with a male jack so I can literally walk around the house with phone in pocket, minimise cables, headphones on and practice.
Strangely, all that noise I got on AmpliTube when I 1st tested is now gone on both versions so seems the 1k2 vs 1k8 issue wasn’t an issue.
Anyway, just a signing off comment to thank you for the awesome build vid and great design. Works like a bomb, and I’m reaching for my electric more often than my acoustic at home now, since I don’t have to unpack my Amp&Kit too.
You have made the internet a better place. Thank you.
June 13, 2012 @ 7:59 am
Excellent!
Thanks for the update.
John
March 30, 2012 @ 6:53 pm
Bonus code: mew521
April 2, 2012 @ 3:36 pm
April 5, 2012 @ 5:02 pm
April 2, 2012 @ 2:04 pm
Hi John
I’m going to make a cable as you instructed.
In my country we use 220v electricity.
Is is safe for my iPod 4g to use it as an amp and effect with 220v electricity
Does it do any harm to my iPod?
Thank You
April 5, 2012 @ 4:43 pm
No problem. The circuit receives its power from the iPod, so you’ll be running off its battery D/C power, not the 220v A/C.
-John
April 2, 2012 @ 7:08 pm
So I screwed up mine some how. No guitar. Music sounds very strange. Vocals are quiet. Almost sounds like a reverb. Any ideas? Switched ground and output?
April 5, 2012 @ 4:45 pm
Probably a short circuit. If you have some breadboard, its worth going through the circuit on breadboard first to confirm its all working. (Or just use alligator leads to piece the circuit together). After you’re sure your components and understanding are working, then you can solder it all together.
-John
April 4, 2012 @ 11:34 am
Hi john
I’m Alireza from post above
I couldn’t find mpf102 transistor here, which model of transistor i can use instead ?
and I also could find the 1N4734A diode
Is that ok to use them with 220v electricity ?
Thank You
April 5, 2012 @ 4:46 pm
Try other JFET’s like 2n5457, 2n5458, j201, etc.
For the diode, you can use any zener diodes with breakdown voltage above 4v or so.
As I mentioned above, no problem with the 220v since your circuit will be powered by the ipod’s battery.
John
April 5, 2012 @ 3:48 pm
In the second video you put the diodes back to back and here you put them head to head,
which one is correct?
and I’m using BF245 any ohm suggestion?
Tnx
April 5, 2012 @ 4:53 pm
Note that the pins on the B245 are in a different order from the MPF102. GSD instead of DSG. Also, the BF245 A,B,C parts have a narrower IDSS range, so be prepared to experiment with the source resistor to find a good value. Someone posted at my blog success with BF245C using very low resistance- 100ohms.
April 6, 2012 @ 6:00 am
Tnx for response
I’m using bf24c
Are u sure about GSD? There are many data shits some says GSD and some says DSG.
I’m confused , Wich one is right?
I built the cable with and with out the electronic stuff but either way I couldn’t get any signal from my guitar to my ipod and speaker
With the electronic stuff i had noise sound in my speaker and iPod but there wasn’t a guitar signal at all
I did exactly as you told
What is my problem?
And i tried to get the sound with mu headset to (sony MDR-EX38ip) but I just heard noise with the electronics and nothing with out them And after that my headset’s remote control doesn’t work , What do you thing? Is it fried up?
April 6, 2012 @ 3:46 pm
I just double checked BF245c datasheets from Fairchild, Phillips and Siemens and they all agree. If you’re looking at the pin side, with the flat side down, it’s DSG. For MPF102, looking at it the same way, it’s GSD.
Please test your circuit on breadboard like I show in part 2 of the video, to confirm your circuit and components are working. Don’t try to skip right to soldering, as mistakes are inevitable.
-John
April 7, 2012 @ 4:28 am
Tnanks John
I have an other problem now
my cable is ground(sleeve) white yellow red(tip)
I couldn’t get it to work , and I couldn’t get any signal from my guitar to my iPod
It didn’t have the 2.8 v between sleeve and first ring when I assemble them like the part 1
What should I do?
April 8, 2012 @ 9:28 pm
All I can suggest is to follow the steps I showed in the videos: first check the bare cable with a multimeter when plugged into the ipod. You should be able to identify which wire has the DC 2.8V between it and ground. If none of them do, then there’s a problem with the ipod.
If you find it ok, then set up the circuit on breadboard, as I show in part 2 of the video, and confirm everything is working.
-John
-John
April 10, 2012 @ 12:55 am
Thanks John
I finally could get it to work
but after I set electronics on fred board it didn’t work again
But i’m gonna fix it
Thanks for your help :))
Ali
April 10, 2012 @ 8:48 am
Hi Ali,
It must just be an unintentional short-circuit. Easy to do when cramming all the components into such a small space. The same thing happened to me the first time I built the circuit. Just be careful that none of the metal parts are touching each other, or touching the shield of the jack.
-John
April 8, 2012 @ 7:58 pm
April 8, 2012 @ 9:52 pm
Sorry I completely misunderstood your previous question! Now that you describe your intended setup in more detail (you just want to plug your mixer into your ipad), I think you could in fact use my circuit. Keep in mind however, that using the mic/headphones port on the ipod/ipad is not the highest fidelity setup- there will be a bit of hiss/noise. If you need higher fidelity, you should use an audio interface with its own A/D that connects through the 30-pin ipad dock.
-John
April 17, 2012 @ 4:04 am
April 17, 2012 @ 12:53 pm
April 20, 2012 @ 7:37 pm
April 23, 2012 @ 10:23 pm
April 25, 2012 @ 2:38 pm
Yes, it’s not hi-fi, but it’s great for practicing on the go.
April 27, 2012 @ 12:27 am
I had to put mine inside an old pill bottle, my soldering skills just aren’t up to cramming all that stuff into such a tiny space, and the pill bottle holds the headphone jack too.
April 27, 2012 @ 8:26 am
April 25, 2012 @ 6:37 am
Hey John.
Thank you for making such an informative video and donating so much of your time to helping others. I built this circuit but have some noise issues, like a loud buzzing. Guitar sounds a bit flat but tone knobs do function. Unfortunately my middle pickup does not function. I used a cable meant to combine a mic and headphones. There were green, red, bare copper for headphone left, right and ground.Then there were two more wires black and white. The white seems to carry the 2.8 v. Does this wire get connected between the jfet and the added resistor for high output pickups? (I used an SD Invader) I used a 1k resistor on the jfet source because radioshack was out of 1.2k (and the staff was not helpful at all) Any suggestions?
April 26, 2012 @ 12:34 pm
Definitely double-check the cable wires using a multimeter to check which wires correspond to the tip/ring/ring/sleeve (as I showed in the first video).
Then make sure you are using them as intended by the iDevice output (tip=headphone left, ring 1=headphone right, ring 2=ground, sleeve=mic).
The 2.8v mic wire needs to be connected to the jfet drain, as indicated by the circuit schematic at https://www.planetz.com/?p=1531 ).
1k vs 1.2k should be ok, but you may need to tweak that, depending on your particular jfet.
John
May 4, 2012 @ 2:37 pm
John,
Thanks so much for the great info.
I ran across your videos while searching for a way to connect a lavaliere mic to an iPhone.
If you have time for a couple ignorant questions, I’d appreciate it.
I also have an acoustic guitar with a Godin Quantum electronics package built in.
So, in an effort to create adapters for my iPad…
1) does the electronics of the acoustic guitar need the transistors and resistors in your rig? (besides 1.5k or so to activate the line on the iPhone?), or would the onboard circuits have a jfet equivalent built in.
2) if I create a rig like yours, would the signal from a lavaliere mike work through your guitar circuitry? or would I need to build a 2nd rig that only had a single 1.5k resistor for the mic?
I’d love to build your rig, have it work for my guitar, then be able to use a 1/8-1/4 adapter to run the mic through the same setup.
any thoughts??
And thanks again for the great videos and wonderful electronic lessons.!!!
Dave
May 8, 2012 @ 10:20 pm
Hi Dave,
Your quantum active pickup has its own preamp so it may be ok to just plug its output directly into the ipad mic input, using the appropriate plug adapters. On the other hand, there would be no harm in plugging it into the jfet preamp adapter described in this video series.
An electret/lav mic typically provides its own little preamp- and that’s specifically what the 2.8V on the ipad mic input is intended to power. So you can probably plug the lav mic directly into the ipad. If it doesn’t provide its own battery power, it will REQUIRE that 2.8V to work, so plugging it into this jfet preamp will prevent it from working (since it buffers out the 2.8V).
John
May 6, 2012 @ 7:58 am
Thanks so much for your video. I built one and it turned out great. I love it, I can now rock out with my ipad2 with garageband and amplitude. Thanks again
William
May 8, 2012 @ 10:13 pm
Nice! Great to hear 🙂
John
May 19, 2012 @ 12:15 am
Hi John, best tutorial I’ve seen and I’ve been searching for solutions like these. I would like to plug my cordless mic into my iPad with an output to the sound desk and have been experimenting with a few options. My concerns are when I sing at an event using my iPad I’m afraid someone could switch on phantom power and zap my iPad? Could I build something similar to above using xeners to prevent phantom power to the iPad without affecting sound output. I’m using vocalive as an app and would prefer using my own cordless mic and not the irig imic. If its possible please could you provide me with a circuit diagram. Thanks in advance!
May 19, 2012 @ 8:51 pm
If I’m understanding you correctly, you’re plugging your mic into the iPad and taking the output of the iPad into the input of a mixer. Because the output of the iPad is standard line level, you’d be plugging it into a regular non-powered line input on the mixer (probably using an adapter to convert from 1/8th inch stereo to two separate 1/4 inch
phone plugs. There’s no danger of receiving phantom power in this situation. Phantom power is only used on XLR mic inputs.
Make sense?
John
May 19, 2012 @ 11:14 pm
Hi John, your understanding is correct except the plugs I use to connect to the mixer are xlr, I don’t use phone plugs as they are less popular than the xlr. Should I bridge pins 1 and 3 on each of the xlr pins for stereo? And if I should only use 1 xlr as an output I won’t have stereo but a blend of left and right ( I would then use all pins). I’m trying to make my setup as simple as possible. I am using an inline 1k resistor on the mic input on the trrs is this correct? It’s okay on a normal sm58 but I get interference when I try to use my cordless beta 58. Thanks Paul.
May 24, 2012 @ 5:12 pm
I think you’re making it overcomplicated by using XLR connectors for the ipad output. The mixer’s XLR inputs will be balanced, have a mic preamp, and supply phantom power. You don’t want any of those things for your line-level ipad output.
I’d use 1/4″ or RCA to connect to the tape input or standard 1/4″ line level inputs.
-John
June 7, 2012 @ 12:25 pm
Also, is there a way to connect the guitar to the iPod via usb, since from what i’ve heard the iPad’s camera kit doesn’t work on it. If it helps, i have ION’s USB Guitar. If not, then would it help quality-wise if i were to connect an amp (Marshall MS-2, only 1W) between the guitar and the iPod? And if i did, would i still need impedance matching and buffing?
June 8, 2012 @ 11:39 am
The more expensive 30-pin dock adapters I mention in part 1 will have higher fidelity since they have their own A/D converters. I don’t know about using a USB audio interface with the camera kit. If your amp has a line-out, you could probably plug that directly into the ipod mic input without worrying about buffering, etc.
June 9, 2012 @ 3:06 am
June 9, 2012 @ 11:17 am
June 11, 2012 @ 11:28 pm
Hi John.
Thanks for the video. I tried to replicate what you’ve done but my ipad2 does not have the 2.8Vdc from the mic input to common(measured with multimeter). I first thought that it was a problem with some setting but even after resetting the ipad2 there is still no voltage at this pin. Do you have any idea why this is?
I would really appreciate any input from you.
Thanks in advance
June 12, 2012 @ 6:52 am
I would suspect a problem in the way you’re measuring it, rather than a problem with the ipad. I don’t know of any way to disable this voltage in the ipad software (but I could be wrong!)
How exactly are you measuring it? You’ll need a proper TRRS plug in the jack, and then check for the 2.8Vdc between the sleeve and first ring. See here: http://pinouts.ru/HeadsetsHeadphones/iphone_headphone_pinout.shtml
I demonstrate this in part 1 of the video:
https://www.planetz.com/?p=1510
-John
June 13, 2012 @ 6:33 am
I used a 3.5mm TRRS plug as the one you were using. I decided to go ahead and just build the device as you’ve done (JFET and everything). Oddly it worked the first time, but then there seem to be some intermittent connection problem at the headphone jack. I haven’t been able to get it working again since then. I’m using it with garage band and amplitube. I also double checked my connections with the multimeter and it seems fine.
My only guess now is that the TRRS jack I’m using is a wee bit smaller than supposed to be (manufacturing default). I will try getting another one. Thanks for your reply.
June 13, 2012 @ 8:04 am
It’s possible the plug isn’t making good contact, but if it worked the first time, I would think it more likely that you have a short inside the plug. The first time I built it, I had a similar problem- and I found that one of the JFET leads was touching the metal jack sleeve (shorting to ground). The problem was worse when I screwed the jack closed, as it squeezed everything together. I recommend opening it up and carefully probe everything, while listening, and see if you hear any differences.
Good luck!
-John
June 16, 2012 @ 12:30 pm
July 5, 2012 @ 11:03 pm
greetings from chile!
July 8, 2012 @ 5:11 pm
July 8, 2012 @ 10:21 pm
July 10, 2012 @ 10:59 am
July 16, 2012 @ 9:53 pm
Nice video John, great job. My question is a bit different I want to run an audio input to my i-device so I can run audio from my computer into a track. Two questions will there be problems with impedance? and can I connect a 1/8″ stereo female cord into the mic sleeve?
July 17, 2012 @ 8:15 am
Audio out from your computer is mostly likely a stereo line-out (line-level).
You should be able to connect this directly to your i-device without impedance problem, but you’ll need to be careful with your output levels to avoid clipping. Also consider that the i-device input is mono, so you can only record the left or right signal from the computer, unless you use a mixer to mix them together to a mono signal.
You’ll still need a special cord. If you just plug in a stereo plug, you’ll only be getting the headphone, but no input.
If you already have a camera connection kit for your ipad, you might just consider buying a cheap USB audio interface, like the SYBA Multimedia USB Stereo Audio Adapter ($10).
-John
July 17, 2012 @ 10:12 am
Great news, my plan is to take a 1/8th” male stereo cable and connect the R & L to the mic wire in a apple headset cord (tip, ring, ring and sleeve). Effectively sending the audio into the app. I like the mixer idea and will try that later. I’ll let you know how it goes.
July 17, 2012 @ 12:47 pm
Hi john,
I’ve recently built the idevice cable but after a few blips, (namely breaking a leg off the only jfet I had, oops!) I’ve decided to leave out the electronics so that I can use it with a standard vocal Mic and I plan to build an adapter with the electronics later. I was hoping you could give me some advice on a couple of things: first of all, can you (or anyone else reading this!) suggest somewhere I can find a small plastic cylindrical enclosure for a reasonable price, big enough to fit the electronic components but no bigger than maybe 25mm diameter? Also, I hoped to plug the adapter straight onto the female jack without an additional cable, do you know where I can find a surface mount male jack (I.e. to screw straight onto the container) orwould my best bet be using a female surface mount jack and male to male coupler?
Thanks in advance for your help and thanks for sharing these great tutorials with us 🙂
Graeme.
July 24, 2012 @ 12:20 pm
Hi Graeme,
You may have to get creative with your enclosure. An empty chapstick container or some such? 🙂
I don’t know about a surface-mount male jack. You may be able to just use a standard 1/8″ plug, remove its enclosure and drill an appropriate sized hole in your new enclosure and have it stick out the end, and affix with a nut.
Would be curious to see what you come up with. Good luck!
John
July 25, 2012 @ 1:41 am
Hi john,
thanks for the suggestions, I was thinking of something a bit bigger but the chapstick could work 🙂 the jack plug and nut is a great idea, don’t know why I didn’t think of it! i’ll need to source some parts (I.e. money and time!) But once I get round to building it I’ll upload pics or a video and link it here.
Graeme.
July 25, 2012 @ 2:54 pm
July 25, 2012 @ 2:57 pm
August 1, 2012 @ 4:33 am
Best Regards from Russia.
August 9, 2012 @ 11:38 am
i wanted you to know that i’ve made the interface with 245C transistor.
it sounded near perfect. any opinion about this transistor?
August 9, 2012 @ 12:06 pm
August 9, 2012 @ 10:59 pm
in the audio cable the second ring must always be ground right?
otherwise it wont work? i mean the cable we buy must be with this specification?
August 10, 2012 @ 10:29 am
August 11, 2012 @ 3:18 am
August 11, 2012 @ 2:29 pm
September 2, 2012 @ 8:01 am
sir i m not getting mpf102 transistor in my area so wich transistor i should try….
September 3, 2012 @ 9:22 pm
There’s a number of alternatives listed in the schematic and in the comments under the videos. J201, 2N5457, 2N5458, etc. You’ll need to experiment with the source resistor value, or use a trim pot.
John
September 5, 2012 @ 5:25 am
September 5, 2012 @ 10:57 am
September 10, 2012 @ 5:49 am
more power to you. guys… 🙂 im happy now
September 15, 2012 @ 2:00 am
sir i didnt get J201, 2N5457, 2N5458 transistor …but im gettng transistor 2N547 , 2N548 insted of 2N5457, 2N5458 is this same or i should try 2N547 , 2N548…..
September 15, 2012 @ 10:49 am
2n547 is an NPN transistor, not a JFET. Please look at the datasheets for the parts you are considering, and compare with the datasheets for the recommended JFETs.
John
October 11, 2012 @ 8:12 am
October 11, 2012 @ 11:13 am
October 15, 2012 @ 12:56 am
Hi, and thanks a lot: I’ve built that following your guide, using what I had at hand (BF246A, resistors and diodes desoldered from old boards), and it works like a charm. Thanks for sharing!
andrea
October 15, 2012 @ 10:36 am
Great! Nice to hear.
Thanks,
John
October 18, 2012 @ 9:53 pm
October 19, 2012 @ 12:35 pm
December 3, 2012 @ 3:48 am
December 4, 2012 @ 1:10 pm
I have seem them for $14.99 at muscian’s friend stupid deal of the day. At that price, just buy one! (and then if you want, you can open it up and learn how it works).
November 25, 2012 @ 1:55 am
Hey John,
Check out my weekend project, based on your design – http://www.facebook.com/drsoda#!/media/set/?set=a.380510375363671.89745.125899167491461&type=1
This isn’t spam.. I grabbed your Idevice interface schematic here and drew it up into stripboard, and made a small enclosure for it. Worked out awesome! Thanks for your ideas and design.
Cheers,
Jeremy Thompson
Jeremy’s House of Guitars
http://www.facebook.com/jguitars
November 27, 2012 @ 5:39 pm
Awesome- looks great! Thanks for sharing your project.
-John
December 21, 2012 @ 5:04 am
John, I followed your instructions for this iPod interface and I’m happy to tell you that my interface cable works great! I used it on my iPod 2nd generation with iShred Live, with much joy and happiness. Thank you.
I was so happy, I updated my iPod as many of the icons were blank for some reason. Big mistake. On restore, an updated version of iShred Live was downloaded which was incompatible with the iPod 2nd generation. After about 2 hours of working with the Apple folks, I found that there is no going back. As for as I know, there is no fix. I tried four other guitar apps and none, that I know of, are compatible. I’m bummed. Anyway, I really enjoyed the project and I would like to thank you for your work.
LVE
December 23, 2012 @ 4:30 pm
Wow, that’s disappointing! Which version of the ipod do you have?
Thanks for sharing this info.
John
January 22, 2013 @ 4:22 am
my brother was the one who’s working with this. he used all the resistors and diodes drawn on your schematic…he tried it on a breadboard (sorry i’m not sure of the spelling), it worked well in both garageband and amplitube, no “zzz” sound, the sound is clear etc.. but when he soldered it on pcb, it didn’t sound that great…it doesn’t have the zzz sound but the sound is not clear…are there any problems with the resistors used? pls reply
January 24, 2013 @ 9:49 am
February 3, 2013 @ 3:58 am
Thank You!!! :DDD
By the way, when I use garageband and adjust the input level to maximum, it starts to have the ‘zzzz’ and the sound quality is very bad….(I use it for recording)
Is it normal to sound like that??
February 12, 2013 @ 4:04 pm
February 15, 2013 @ 7:16 pm
by the way, when i checked amplitube to see if the effects work, it doesn’t.. the output sound is just the same with no effects in it….does amplitube work with yours?
February 19, 2013 @ 1:16 pm
February 20, 2013 @ 5:21 am
February 19, 2013 @ 1:16 pm
January 28, 2013 @ 4:16 am
great project,I found your youtube videos to be very informative so over the weekend I dug up the parts and made the interface only I put it into a 2 x 3 inch inclosure with a 4 ft wire to the 3.5mm plug, everything connects directly into the box..works great even tho I have a jamup plug interface the project was fun and my friends think I am McGyver like..thanks now how can I hook up a webcam to an ipad 1st generation
January 28, 2013 @ 7:52 am
Cool! I’m sorry I don’t know any way to connect a webcam to the iPad 1.
John.
Simple JFET Preamp for an iDevice Guitar Interface -
January 28, 2013 @ 10:07 am
[…] Part 3, I’ll demonstrate how to assemble the circuit so that it fits entirely inside the […]
February 9, 2013 @ 3:54 pm
I have a jamup interface and an irig interface and both have different issues and clarity problems whenI conect them to my 50 watt tube amp or my 20 watt tube amp…even my diy powered Ispeakers, but wwhenI use the interface I built with your schematics and videos it workd flawlesly with the ipad and connected to any amp or powered speaker system, it even sounds good using it through my universal bluetooth connector…no buzzing cracling feedback or anything with either ampyou should build em and sellem on ebay…works better than the pros interfaces…
February 10, 2013 @ 9:06 am
Excellent! Thanks for the kind message.
John
March 4, 2013 @ 11:54 am
March 8, 2013 @ 1:51 pm
March 13, 2013 @ 10:31 pm
If anyone has built this other than in the plug, as shown here, could you share a picture? Curious to see what enclosures people choose.
March 14, 2013 @ 8:11 am
See Jeremy Thompson’s comment above for one example.
-John
March 14, 2013 @ 8:34 am
Feh. Facebook won’t show it to me.
March 16, 2013 @ 2:49 pm
Yay, I finally got this built. Not in a jack but on a piece of perfboard, following the walk through in Part 2. I highly recommend that. Just lay out the parts, triple check the data sheets and resistor colors, and you’ll have it done in no time. Part 3 was like a master class: I could appreciate it but was lost.
It sounds as good or better than the counterfeit (grrrr) iRig I was using so I’m pretty pleased.
March 26, 2013 @ 9:41 am
Hi,
Just built the project on BF245C. Seems to work, but tone dials in guitar have no effect. I’ve checked things twice, but don’t see any issues. What can be the cause?
Thanks,
Lukasz
March 26, 2013 @ 5:31 pm
If the tone controls work when plugged directly into your amp, then it’s likely that the buffer isn’t working properly. You can see in my video when I demonstrated without the buffer, that the tone controls didn’t work right. So doublecheck your work with the schematic and confirm that it’s all set up properly.
John
March 29, 2013 @ 7:25 pm
April 7, 2013 @ 8:57 pm
April 2, 2013 @ 3:39 am
April 4, 2013 @ 5:53 pm
April 4, 2013 @ 5:55 pm
April 6, 2013 @ 11:12 am
Thank you so much for posting this series, I have just completed this project and it works just great! Tried it with Amplitube and Garageband in my 4th Gen iPad, really pleased!
I had to put the amp into a plug though as I could not find a line socket with enough room here in the UK, but this does make it self contained and a great practice tool when on the move.
One problem I did have was that the only cable I could find had a very big plug moulding that I had to re-shape to allow it to go into the ipad cleanly with my smart case in place, but other than that quite straight forward.
Excellent project, thanks.
Julian
April 6, 2013 @ 11:30 am
Thanks for the message Julian. That’s great to hear.
In some ways, I wish that I had used a plug instead of a female jack for my cable. There’s been a couple times when I forgot to bring a short male to male cable to plug in my guitar.
-John
April 7, 2013 @ 4:52 am
April 7, 2013 @ 8:59 pm
April 8, 2013 @ 1:21 am
April 10, 2013 @ 3:37 pm
April 19, 2013 @ 2:57 pm
April 19, 2013 @ 3:05 pm
April 19, 2013 @ 3:24 pm
April 23, 2013 @ 7:27 am
April 23, 2013 @ 1:15 pm
April 27, 2013 @ 7:58 am
Hello!
What a source resistor value needed for 2N5457. Please help!
Followed by the scheme but the sound is not clean (very overloaded) ((
I think it is: a bad transistor or need to experiment with the source resistor value.
Maybe this value is already known?
Heeelllppp!!!!
P.S Forgive me for google translate
April 27, 2013 @ 9:16 am
Thank you! I found the answer here!
https://www.planetz.com/simple-jfet-preamp-for-an-idevice-guitar-interface/
April 27, 2013 @ 6:07 pm
Cool, glad you found it.
John
May 15, 2013 @ 8:33 am
I have built your circuit and it works great. Thanks for sharing that.
I was just wondering how hard would it be to add a bypassing switch to this to make it work much like the iRig Stomp? I’d like to make it just like so, except of course it won’t have the input level knob. Unless that is something that can be added as well.
May 16, 2013 @ 1:10 pm
What would your switch be bypassing?
If you mean a mute switch, just to cut your guitar signal, then yes, that would be easy.
If you mean an on/off control switch for an effect running in your guitar app, then no- there’s no digital control interface here- it’s pure analog I/O.
-John
May 16, 2013 @ 7:23 pm
Sorry if it wasn’t clear. I’d like the switch to act like: Off=guitar to amp, and then On=guitar to idevice to amp. This is basically how the iRig stomp works so I’d like to replicate this switching function on your circuit.
I’ve started to play around with the idea and it looks like I may need at least a DPDT switch to make this happen. Or a 3PDT to add an indicator LED.
May 17, 2013 @ 11:08 am
I see. Yes, you’re on the right track. Look up a wiring diagram for a passive A/B switcher and you’ll be all set. Here’s one to get you started:
http://www.beavisaudio.com/projects/Looper-Switcher/index.htm
-John
June 5, 2013 @ 11:20 am
June 5, 2013 @ 11:22 am
June 5, 2013 @ 11:24 am
June 6, 2013 @ 3:23 pm
You can also experiment with the R2 resistor value.
June 7, 2013 @ 1:19 am
June 5, 2013 @ 11:25 am
July 18, 2013 @ 10:46 am
July 31, 2013 @ 6:40 pm
I just want to know If I use it whit a bass guitar will it work?
I play a Yamaha TRB 5-II, it’s an active bass, 9 volts battery, I must
Know If I can connect my bass to the iPhone using this cable
I’m afraid to damage my iPhone. Thanks.
August 1, 2013 @ 1:09 pm
Yes, it should be fine. But really, with active pickups, your guitar already has a preamp in it that will buffer out the 2.8v. You should be fine with a simple cable adapter and no additional electronics.
-John
August 1, 2013 @ 5:27 pm
But If I connect my TRB bass guitar directly to my
iPhone without any Idevice like irig, will it work? And if it’s
Works could it produce noise, or distortion, can I record a bass good bass
Line, I mind a clean bass line sound? Thank you john for advising me. I’m from Colombia
And it’s expensive for me to record my sound in a professional studio, so I want
To do it in my iPhone 5, and iPad but I don’t want to spend much money doing it, jajjajjaja
I hope you understand.
August 6, 2013 @ 8:28 am
I´m guessing it´ll just work- I suggest you give it a try. Should be easy to do the experiment. If it´s no good, then you can consider building or buying a preamp circuit.
John
August 27, 2013 @ 10:30 pm
PS: sorry for my english
August 30, 2013 @ 10:04 am
August 28, 2013 @ 11:48 am
September 1, 2013 @ 4:02 am
September 1, 2013 @ 4:04 am
September 4, 2013 @ 3:18 pm
September 6, 2013 @ 4:19 am
September 7, 2013 @ 5:34 am
September 15, 2013 @ 4:59 pm
John – thanks so much for your information… this is really well put together and easy to understand.
I’m in the process of building a DIY stomp box that utilizes iPhone & Amplitube for live use (like a passive iStomp). I wondered if you could advise on the best way to convert the stereo headphone output signal to an unbalanced output so I can feed it straight into a DI box on stage… Would this need any components to ensure the best quality signal, or is it just a matter of adjusting the volume on the iphone? Any ideas/suggestions would be really appreciated.
Many thanks
Mark
September 17, 2013 @ 9:24 pm
Hi Mark,
I haven’t tried it, but I suspect you can just plug it in directly.
Give it a shot!
-John
September 18, 2013 @ 1:45 am
Thanks John – will try it out …
Mark
November 8, 2013 @ 1:57 pm
Thanks so much for making this, it is so helpful. Can you please tell me,
if I want to plug it into an amp or another pedal will the headphone jack
be the correct impedance or would it need a second circuit to adjust the
output?
Thanks again
T
November 17, 2013 @ 10:38 am
to make the port Hi-z? and reduce the delay?
November 21, 2013 @ 6:58 am
interface like the Apogee Jam? $99.00 sure seems a bit high for it! 🙂
December 10, 2013 @ 9:20 am
cramming all the components into a DB9 plug shell case dead bug style.
December 12, 2013 @ 9:08 am
dear John, your video is very informative… we are trying to use iRig as our Phone patch/podcast device that’s why your video caught my attention… i want to build exactly the way you build it but the problem is here in our country (Philippines) i believe MPF102 transistor its not available and also the R3 10k. im sorry… i dont know to much about electronics… hope you can help me to create a new gadget that parts are available here in our country. thank you very much i really appreciate the video
December 13, 2013 @ 4:45 pm
There is a list of alternative JFET parts in the schematic- you should be able to find one.
As for the resistor, the values don’t have to be exact. But 10k is a very common value and you should be able to find it without difficulty.
-John
December 15, 2013 @ 7:21 am
thanks… im trying to use 2N5486, will it work? do i have to use different resistors to this project?…. God Bless
December 15, 2013 @ 3:45 pm
dear john… i’m a little bit confused….. on your part 2 video on the breadboard you connected the diodes together differs from the part 3 of your video. which do we prepared? sorry I dont really knows how diodes works
January 3, 2014 @ 12:31 pm
In this case, the zener diodes are wired back-to-back, to catch voltage spikes of both polarities. It doesn’t matter which order they will go in.
(sorry for the delay in replying- this comment was filed under my spam folder for some reason!)
-John
December 15, 2013 @ 7:30 am
it may not be you interest… but may i ask you to create a video for simple device that can be used specifically for phone patching as answer live cellphone on a audio mixer….. thanks a lot. more power to you john, thank you for having sometime reading my request.. hope to watch more videos from you…
January 3, 2014 @ 1:20 pm
Hi Arthur,
Sounds like an interesting project idea, but unfortunately I have very little time right now. Do some experimenting- I’m guessing you can figure it out!
-John
January 5, 2014 @ 8:10 pm
Hi John, first I need thank for this really awesome tutorial that you made for us and apologize because my english is not so good (im from Brazil).
Your interface is great and have a great sound quality too!
I have a doubt and i hope you can help me.
When i use any effect on any app and put them on backgroud to play a video or music at same time, the video or music are also with same effect. Do you know what i done wrong?
Thank for everything, you are a great teacher!
January 5, 2014 @ 9:09 pm
Hi André,
This would have nothing to do with the interface itself. You should contact the developer of the app that you are using to produce the effects.
Good luck!
John
February 3, 2014 @ 5:59 am
If I’ll use russian jfet’s KP303E or KP305D, what resistance of R2 should
be? or how I can determine it…
February 10, 2014 @ 8:57 pm
March 20, 2014 @ 7:34 am
ultimately I’d like to have stereo line level input to an iPad. Though I
think you’d have to use the lighting connector.
May 7, 2014 @ 6:27 pm
Great tutorial. Got the thing on the breadboard, and the iPad doesn’t really recognize there is anything at the input (turns the internal mic on,) unless I hot plug R3. I used all the same components as you (Mammoth, awesome!) For some reason, the iPad needs to see that resistance change. Any thoughts?
Also, is the feedback ridiculous for everyone when using high gain amps in Garage Band or Amplitube? It’s practically unuseable. Have I shorted something?
Thanks for your time!
May 7, 2014 @ 6:54 pm
There must be a wiring mistake or short. Good thing it’s on breadboard and there’s only a few components… Just tear it up and try again 🙂
I haven’t really tried high-gain, but I’m guessing that feedback will be a weakness of any implementation that goes through the mic/headphone jack.
-John
May 8, 2014 @ 6:26 pm
I’ll give it another go. I’ve rebuilt it a bunch, but I must be making the same mistake every time. Thanks for still answering questions on this old video! Thanks for being so patient with all of us.
May 14, 2014 @ 6:58 pm
try to reverse the polarity of your diode…
May 14, 2014 @ 7:01 pm
its a long shot solution but it might work,,,
May 22, 2014 @ 8:29 am
Hi Arthur,
Reversing the polarity of the zeners will have no effect.
-John
June 12, 2014 @ 5:21 am
June 16, 2014 @ 5:12 pm
I made my own version of the iRig for use with MacBook Pro (with only one
audio port), now I want to adapt it to also be used in iPhone and iPad. I
need to add these components.
Can you help me with a question?
You use Gate, Source and Drain to designate each wire of the transistor.
But, the language generally used is Emitter, Base and Collector.
Can you tell me who is who? Gate is equal to Collector; Source equals Base;
Drain equals Emitter?
Hope you can help me. Of course, not wanting to take your time.
Thank you!
June 17, 2014 @ 10:06 am
thing I noticed don’t know if its normal, but when I’m connected to garage
band guitar amp I cannot pan left or right, but after I have recorded and I
switch to the track section I can then pan my recordings. Is this normal or
have I made a mistake somewhere in my wiring? Thanks for all the info btw.
June 17, 2014 @ 10:16 am
of cable. I used J201 transistor SMD version and thats the only
difference.
June 18, 2014 @ 7:57 am
shorted…too much crammed into a small space. Will try again on a board
this time.
August 1, 2014 @ 7:51 pm
I’ll try to do this and put it in a box. So in this case I can use my
default cable.
Also I’m considering using 2 P2 Jack (3,5mm). One I use to plug any cable
to send the signal to my iDevice and the other to my headphones.
But my question is: Can I use a USB port to output the audio signal and
then plug a cable to transfer the signal to my computer, or in this case
your project need some changes.
Sorry if this is a really dumb question, because I really know nothing
about eletronics.
Great video tutorial. You are very instructive..
Tks in advance.
September 1, 2014 @ 10:41 am
like to know if i can replace this by another one. Please send me a message
i’m very impassiant to try this on my stratotaster ! Oh, and, by the way,
very good video
September 22, 2014 @ 5:53 pm
Hello, it is very likely that my question and have answered in his video, but I’m from Chile and my English is not very good.
My question is about or diodes.
Is it one or two?
Are the two equal?
How are they connected?
in advance thank you very much!
September 24, 2014 @ 9:18 pm
You can see the schematic here:
https://www.planetz.com/simple-jfet-preamp-for-an-idevice-guitar-interface/
The two zener diodes are identical, connected back to back, from the gate to ground.
-John
December 20, 2014 @ 6:34 pm
I can find is Neutrik NJ3FC6.
December 30, 2014 @ 7:53 am
design. Would a variation of this be used to connect the output of an ipad
to a balanced microphone input on an audio mixer? That is, the 3.5mm male
ipad mini jack to a male XLR?
January 23, 2015 @ 12:37 pm
March 29, 2015 @ 12:21 pm
resistor values? If so, what to?
March 30, 2015 @ 12:45 pm
For those of you asking about the J201, or other jfets, experiment with the R2 value using a 50k trimpot, to find a value that works well. Then measure the trimpot resistance with a multimeter, and replace it with a comparable resistor.
-John
May 11, 2015 @ 5:34 pm
Hey! First of all thank you for shearing and explaining it with such a detail! Sorry for the question, but I am not an “electronic man”… Here in my country I could only get a BF245A for the JFET. How should I check the adjustment of R2? Just by ear or measuring some voltage with the multimeter?? Thank you in advance and regards from Argentina!
May 12, 2015 @ 2:59 pm
I just experimented by ear. Using a small-value trim pot can help you find a resistance value that works well. Then, you can use a multimeter to measure the value you found on the trim pot, and replace it with a comparable resistor.
May 13, 2015 @ 4:45 pm
Thank you John!
July 15, 2015 @ 8:32 am
QUE NO HABLO INGLES,, … GARCIAS…
July 15, 2015 @ 8:34 am
July 26, 2015 @ 4:03 am
Just a question. I made this on a breadboard and worked just fine.
After soldering it still works like a charm. But when i change the volume
or change pickups i van hear thuis clearly within amplitube.
Any suhhestions ?
I changed the jfet for a new one.
Thanks in advanced for awnsering me
Kind regards
Jelle
October 11, 2015 @ 11:04 am
Hi just wondering if will work for an acoustic guitar with 9v opamp preamp driving a piezo pickup..be great if it did?? I think it would be easier for me to build into a small mint tin, headphone lead and jack ( with some strain relief of cable ties/hot glue, and have a female guitar jack on the other end. Be a very short lead..say 6″. Can you see any problem doing it that way? Also another thought. If you added an led would the 2.8v be enough to power that as well as ur circuit..when plugged in??? Its not a necessity to have an led..
October 14, 2015 @ 9:25 am
You probably don’t need this, since the preamp in your guitar should do the right thing. I’d try just plugging your guitar directly into the iPad (with the appropriate passive cable adapter), and see what happens!
November 25, 2015 @ 7:07 pm
Hello man, great video but could u please help me with tecnique because u didnt say what resistence it is. I just want help could u pass me circuit with photo or something im desesperate to make it
November 30, 2015 @ 12:32 pm
Hey there- this is part 3 of the series. The schematic is in part 2:
https://www.planetz.com/simple-jfet-preamp-for-an-idevice-guitar-interface/
January 18, 2017 @ 9:13 pm
First of all, thank you for posting this tutorial. I plan to take on this project this weekend. I have a question about a 4 conductor audio cable I picked up from the thrift store. In part 1 of your tutorial, you say any TRRS cable should work, but I just checked the pinout on my cable and the ground is the base ring. After researching a little, it looks like this is a cable for older devices that use OMTP standard (L,R,M,G), rather than CTIA standard (L,R,G,M) which is used on newer devices.
I guess my question is: Will this cable work if I follow your tutorial? I assume the answer is no, but I could easily buy OMTP to CTIA adapter for a few bucks. I was just hoping you could confirm because I didn’t see it discussed in any prior comments.
Thanks again. You’re the man!
January 18, 2017 @ 9:38 pm
I think it shouldn’t matter, since you’ll be cutting off one end and connecting it to your circuit as you want.
Follow my guide to identify which wires are attached to which tip/ring/ring/sleeve- at 3:10 in part 1 of the video series: https://www.youtube.com/watch?v=p1T8QmQowVQ&t=3m10s
Good luck with the project!
-John
January 19, 2017 @ 6:07 am
I would agree that it doesn’t matter how the Left, Right, and Mic wires are assigned. After all, a wire is just a wire. It doesn’t know what type of signal it will carry. So wouldn’t the pinout be truly assigned when you plug the jack into your device? If that’s the case, my device would be sending the Mic signal into the ring that becomes the shield of all three wires. If I were to solder the rest of the circuit together as you have done, I wouldn’t have a ground going to both the 1/4″ jack and 3.5mm jack.
This is all new to me. I appreciate your patience.
January 19, 2017 @ 10:52 am
Ah yes, sorry I didn’t read your initial message carefully enough. That would be a bit strange having the audio signal carried on the shield of the the 3 wires. Would sound noisy. You probably should look into that adapter, or just buy another cable. The one I used was only like $5…
January 22, 2017 @ 6:51 pm
I bought a new cable, but I had the same problem because it was also configured for devices that use OMTP standards. So I ended up cutting the epoxy off the jack and re-soldered, swapping the connections for the ground and the mic. I did everything else exactly as you showed in your tutorials and everything is working great! Thanks again for your help!
January 23, 2017 @ 10:43 am
Nice job! Great to hear.
-John
Building an iDevice Guitar Interface Cable – Planet Z
May 2, 2017 @ 8:49 pm
[…] part 2 and part 3, I’ll explain all the electronics and show you how to assemble the interface, but for now, […]
August 17, 2020 @ 12:56 pm
Hi John,
I made this yesterday and it works beautifully. Thank you for the videos and schematic.
Would such a circuit work for tapping into my computer headset, so I could tape record my phone calls? The headset uses a TRRS plug. It’s the Plantronics 5220 Blackwire. I would like to be able to plug the headset’s TRRS plug into something like your iDevice cable , then have a TRS plug that could plug into my little digital recorder.
August 17, 2020 @ 4:41 pm
Hi Al, Glad the project worked well for you. Your call recorder sounds like a pretty different project. The headset is presumably drawing power from the laptop jack (or from its USB adapter). You’re wanting to splice in a separate cable over to your recorder. I *guess* you’d want to make a little Y adapter (input is trrs to the computer, output 1 is trss to the headset, and output 2 is trs to the recorder). IOW, you only pass through the power to the headset mic. The audio from the computer is sendt to both the headset and to your recorder. Probably no fancy circuitry required, just a simple set of wire connections. You could try with some alligator leads and a couple exposed jacks. Good luck!
-John
August 19, 2020 @ 3:57 am
Thanks John. That makes sense. I will try it out and see how it works!
September 2, 2020 @ 10:09 am
Hi John,
I made the Y-splitter for my headset and … it works! The audio from the mic is the same loudness as the incoming audio. Usually, the mic is much quieter. No fancy circuitry was required. It even passes through the control functions – volume and mute. Thank you for your help and your great projects. Please keep up the good work.
September 2, 2020 @ 10:12 am
Hey Al- thanks for following up. Glad it worked out! Nice job.
-John