This is a library of perfboard and single-sided PCB effect layouts for guitar and bass. I'm not an electrical engineer by any stretch of the imagination, just a DIY'er who likes drawing layouts. It is meant for the hobbyist (so commercial use of any of these layout is not allowed without permission) and as a way to give back to the online DIY community.

Wednesday, July 12, 2017

iRig Preamp

Got several requests for this one. Basically, it's small preamp to plug into a mobile device for use with apps like iRig. Pretty simple circuit. Shouldn't be hard to fit in a 1590a or even smaller since you don't need to include a footswitch.

32 comments:

  1. Very nice, do you think i can use this circuit for an Arduino Analog input? I wanted to use a tuner program i found, and states that i need an amp. Do you have the circuit? Thanks

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    1. Don't know about the Arduino. You'd have to do some research. This is really just a pre-amp. If you need an actual amplifier you'll probably need something based around a 386 or something.

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  2. But the iRig - certainly the original one that can be found for $5 from various chinese sellers for some reason - is a jfet device?

    Schematic and discussion here: http://www.diystompboxes.com/smfforum/index.php?topic=85913.20

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  3. Hi, thank You for Your work. I think there is a little mistake: Volume2 is out, but on the layout there is Volume 2 wired to 560 ohm resistor. I think, it should be Volume 3.
    Regards.
    Guido

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    1. Yeah, that's just a typo. Volume 3 is the out.

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  4. thanks.. got my request.. how can i add a footswitch like the original irig stomp?

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  5. It only work with iOS? Or it's only a preamp to connect your guitar to your phone? Thanks

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    1. I believe the iRig app is on both iOS and Android.

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  6. japanese parametric eq.. please!!!

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  7. Does the output go directly to the cell phone? What kind of jack should I put?

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  8. Hi, any ideas how/where to add a headphone jack, to hear what is coming back from the device? Can't see how to do it!

    Thanks so much for all the hard work you put into this site!

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    1. From my understanding that won't work here. This is just a preamplifier and actual amplification is being done by the mobile device. So you'd need a secondary out from there.

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    2. Hi Joe

      It's crazy simple, you have to use 4 pin 3.5mm jack.
      You connect irig output to the pin that is specified for the microphone, and then connect your headphones to 2 pins that are specified for right and left channels.

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    3. So the 'in' on the board is for the 1/4" jack (guitar input)? The guitar input doesn't seem to be labeled, but according to what you wrote above, everything else is done off of the volume pot, which makes sense.

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    4. Yes. The "In" pad is where signal comes in, from guitar, pedals, etc.

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    5. Realizing this thread is 3 years old (thanks for responding on it, by the way), the iRig 2 has since come out with some added features, most notably, a gain control for hot pickups. If I wanted to add one, where would I put the linear pot (and what value would you recommend?) I'll add it in since I'm still finishing it up and report back.

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    6. Assuming they only altered the original circuit and didn't redesign it altogether, the gain control is likely a pot at the input (basically another volume control, just at the input) or a pot in place of the 10k resistor just above the IC. For the former I'd try just a 100k pot, input to lug 3, to the circuit from lug 2, with a 1k resistor from lug 1 to ground. For the latter I'd try a 10k pot with lugs 2-3 connected to each other and the right pad of that 10k resistor, and lug 1 connected to the left pad.

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  9. Hi. How can I get the actual size of the Layout for I am able to etch this on PCB? Thanks

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  10. can i use this as a headphone preamp? this is mono (single channel) right?

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    1. It is mono, but I think you'd need to run it into an actual amplifier of some kind to drive headphones. Check out the ROG Ruby amp instead.

      http://effectslayouts.blogspot.com/2015/05/run-off-groove-ruby.html

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  11. can i use it for connect my guitar to "Guitar Rig 5" on the computer ?? that will be awesome

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  12. Can the 4001 diode be substituted with a 4148?

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  13. Hello, I am confused as to how volume 1 and volume 2 works? The other 1 connects to common ground and the other one cames from the output of the op amp.

    Where should I connect the 3.5 mm jack jack cable that will go to the phone?. Thanks in advance

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    1. It's a TRRS plug. T is Left, R is Right, R is Gnd and S is Mic. You need to solder the Mic to the Output (lug 3 of the 1KA potentiometer). The Left/Right are outs, so they won't be soldered on the board, they are the new Output itself. So, the Mic goes into the Output of the board, and your new Output will be your Tip/Ring from the 3.5mm plug. Btw, this way you can make it True Bypass as you normally would.

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  14. It's verified, works like a charm!

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    1. Working perfectly with a Motorola cellphone, thanks again!

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