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.

Thursday, July 30, 2015

Guitar Direct Box

Got a request for an active DI, which coincided with a project I'm working on, so it seemed like a good idea. This one's designed by Samuel Groner and modified by Jack Orman. The schematic came from his blog and can be found here, along with some other info about the circuit.


58 comments:

  1. From the link in the desctiption, it says "The “GND” point should be isolated from the chassis but Vee can be connected to chassis."
    Can someone explain it to me? I thought Vee and ground are the same in DC.

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    1. That schematic was drawn a little strangely. GND in the schem is VR (yellow in the layout), and Vee is Ground (green). Wire it the way you normally would a pedal with VR (tube screamer, rat, etc). Hope that helps.

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    2. It did. I realized that a few moments before reading your reply, thank you for confirming it for me. I got the board all etched up. I still have to source components though. Hope to finish it this week.

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  2. Hi. I built this and it works reaaally nice. You can mark it 'verified' unless there's other requirements to that. I really don't know. xD

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  3. hello.. i'm a newbie here.. is there a schem for ground lift and speaker through for this d.i. box?

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    1. Ground lift wasn't included in the original schem, but I think all you'd have to do is add an on/off (SPST) switch between ground and the X pin of the XLR out. For speaker through I think all you have to do is add a 1/4" jack and wire it to the input.

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    2. thanks for your reply.. really appreciate it..

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  4. i made this box and i don't know how to use it.. sorry for me..

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    1. https://www.google.com/search?espv=2&biw=1401&bih=885&q=What+is+a+Direct+Box%3F

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    2. the input is where the speaker out or the line out of the amp inserted?

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  5. i can make a diy pedal but don't know how to use this thing.. sorry..

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  6. Any chance you draw a layout for a ABC box like the Morley ABC Selector? http://www.morleypedals.com/abc09es.pdf
    Thanks!

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    1. Don't really need a board for one of those. Just wire it point to point like this:

      http://i38.tinypic.com/4zzqxu.jpg

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  7. At GND wire 370R 1/2W resistor in parallel 1UF/ 630V non polarized, add a switch for LIFT/ Ground. I do that to kill ground loop, I will try in VEE to see what happens.

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  8. is it working with phantom power from mixing console ? how to put some led indicator there ?

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    1. This isn't designed for use with phantom power. You'll need to connect it to a 9v supply. If you're wiring it with an on/off switch follow the typical off board wiring.

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    2. But it Will work whith a phantom power micer right?

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    3. Not that I'm aware of. It's designed to be used with a regular 9v power supply

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  9. Hello i'm a newbie for this and i want connect this layout to my pc soundcard and my wiring is guitar - pedal - Split L and R - two Direct Box (your layout)for R and L - Stereo Line in my pc soundcard so this is right or wrong ? or i must need balance to unbalance converter ??..

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  10. I would split the signal after the direct box using either a XLR to stereo cable. The balanced out pads on the layout is for the XLR output jack, and unbalanced out pad is for 1/4" output jack.

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  11. i made this layout but i dont know how to wiring it.... can i use the balanced output with an stereo jack instead of the xrl???? i want to use it with the pc soundcard so i need an output jack....

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  12. My 10R resistor has burned when I turned it on. Any idea on what could have happened??

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    1. Sounds like polarity may have been reversed on your power supply.

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    2. My resistor is burning up with a center negative and a center postive supply. Anything else that can cause the 10R resistor to fail tried 2 so far..

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    3. has anyone found a solution to this. Just plugged it in and have burned through 2 10R resistors. I want to get this to work.... I'm going to take a look over the build to make sure that it is correct.

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    4. So after some debugging and checking component placing I noticed that I had placed the IC in upside down. I feel foolish, but I'd rather tell people and have them not make the same mistake.

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  13. This comment has been removed by the author.

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  14. Hello, is it compatible with bass?

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  15. Friend: is wrongly verified, R9 and R10 are GND, correct to VEE and works correctly. Thank you for your work!

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  16. Polarity with DPDT on-on switch between -out and +out, is correct?

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  17. The negative of unbalanced output is connected to GND or to yellow line?

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    1. i think 10k resistor (out+ and out-) that connected to 47 ohm and yellow line, is supposed to connect to green line (not yellow line)

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    2. You may need to up the wattage of that resistor

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  18. Question: are 1/2W resistors really required, or can I use 1/4W resistors?

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  19. Hi!

    Is this DI suitable for bass guitar? I want to add it to the Deadastronaut Bassman Preamp in order to build a proper preamp.

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    1. Yes it should work just fine for bass

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    2. How can I send you a request (w/ schematics) for a pcb besides via social media (i have no social profile of any kind)? I can't find any email in this blog :(

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  20. can we use this with microphones or electronic keyboards?

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  21. could you post the schematic please? thax

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    1. Basically i have a request for a proper bass DI, here it is:

      https://elektrotanya.com/samson_lh_1000_bass_amp_sch.pdf/download.html

      The part of the circuit of the request is in the upper left corner, from D6 to C5, it's the DI from the LH500 /LH1000 bass amplifier from Hartke, the "guitar direct box" it's very good on guitar but it's not good for the bass guitar since the signal I get out of it is very distorted even with the gain pot set to minimum.

      The only way to get a clean sound is by lowering the volume on the bass guitar itself, but at this point it's almost useless using this DI (yes, i could put a volume pot before the IN of the signal of the DI but I think it's an ugly workaround)

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    2. Schematic is linked in the description.

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  22. so I'm told the direct box has a transformer, does this box box work like some industrialized ones?

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    1. Passive DIs use a transformer, but this is an active one. Meaning it needs a power supply. No transformer necessary with this design.

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  23. should the xlr pin "1" be connected to the source GND?

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  24. Putted a B10k pot cause I cant find a C one ... tho, how should it be wired ? What actually 1/2 means ? Pin 1 or 2, or BOTH pins into the same hole? Trying to make it give less output (used a 082 instead of 072) thx for the utility !

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    1. 1/2 means both lugs 1 and 2 of the pot. Just run one wire from the board to the pot and then put a jumper across both lugs.

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    2. works both ways but yeah just runned one wire and putted a jumper... Is it possible to add a pot on the input to control input signal without having to turn down on instrument ? I noticed that when Pots of instruments are below half works like a charm but i usually use my instruments around 80% of volumen and the signal outcoming the DI is gained as hell (tried with a B10K , A500K - this was worst -, and stayed at B5K for gain pot ) Thx for reply !

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    3. Yeah just but an A100k, 250k or 500k pot before the input. Wire it like a volume pot and it should do the trick (input to lug 3, output from lug 2, lug 1 to ground).

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    4. indeed it do the trick, but could it make some noise ? or am I just snowballing mistakes like cold soldature and stuff? Imma do this from scratch again ... really wishing to keep this as clean as possible. Salutes!

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