Active Direct Injection box (DI)

5/8/2014

42 Comments

Here's an active DI box I built for my studio from a schematic by Elliot Sound products.

42 Comments

Declan

9/15/2015 01:29:37 pm

Will this schematic work with 1/4 watt resistors?

Fredrik Lyxzén link

9/15/2015 02:09:58 pm

The schematic suggests using 0,5w resistors, but I've build two of these with 1/4w resistors that are working just fine.

Bundis

10/17/2015 05:07:01 pm

Is threre a way to power this with a 9V power source instead of phantom power?

Fredrik Lyxzén link

10/18/2015 11:23:18 pm

This layout would need to be changed a bit to run it from a 9V battery. But there are a couple of vero layouts of the same DI circuit but with battery only on the tagboard effects forum. So have a look there in the contributions section and you should find it. Cheers / Fredrik

Larry Coates

8/23/2022 09:28:58 am

See the schematic for a dual powered Active DI at this link:
https://sound-au.com/project35.htm Note that it is slightly different from the original board layout specified here. Note the values for C4 & C5 as well as for R13 which has a different purpose than limiting the current into a LED to show that power is on. You might also consider using a "Center Off" type of switch if you are using a pair of batteries to power the Active Direct Injection device.

Matthias Stockert

11/20/2015 10:17:56 am

Can I just wire a second mono jack in parallel to the input to have a link-out-jack? Any problems about this, signal oder treble loss?
Thanks in advance!
Matthias

Fredrik Lyxzén link

11/20/2015 04:06:51 pm

Hi Matthias,
Yes, that's how many DI's are wired up so it should be fine. :)
/ Fredrik

S Beblis

1/2/2016 12:14:56 pm

How does this get powered off of phantom, instrument gets plugged through input and the XLR is the output to the board or recorder, I am hoping someone can guide me ?

Fredrik Lyxzén link

1/3/2016 08:39:52 am

Hi S Beblis,

The XLR output is also the phantom power connection and should be connected to the XLR mic input of your audio interface or mixer. Most modern audio interfaces or mixers can supply phantom power via the mix inputs..

Sargon Beblis

1/3/2016 09:06:49 am

So instrument gets plugged into circuit and xlr to interface input and phantom power needs to turned on , on that particular channel, is that correct? Thank you again, appreciate it

Fredrik Lyxzén link

1/3/2016 02:23:30 pm

That's correct :)

Steve

3/25/2016 08:43:53 am

The original Schematic from Rod Elliott had R4 & R5 listed as: 10K. Your project shows: 100K. Is that an error?

Fredrik Lyxzén link

1/3/2017 12:05:46 pm

Hi Steve,
Sorry, your post missed my radar. R4/R5 is just for the second op amp stage inverter for the balanced output so either 10K or 100K are both ok, as long as both resistors are the same value.

John

12/28/2016 08:25:57 am

What voltage rating electro caps should be used with this? I know phantom power is 48v, but putting 470uf 100v caps will put a damper on the size of the circuit haha

Fredrik Lyxzén link

1/3/2017 12:03:58 pm

The actual voltage present at the caps are much lower thanks to the 100R resistors and 24v zener diode, so 50v rated caps should be fine. :)

John

1/3/2017 12:09:12 pm

Fredrik, thank you for the enlightenment! I didn't even think of the 24v zener =X Thank you!

Marianitem

1/8/2017 12:28:36 am

Hi,
May I add this board after the output of a Sadowsky preamp clone? Do I have to add anything, or just feed the this boards input with the preamp output? Can I just link both the unbalanced tip and the input of this board?
Finally, any chance to get a +9v from this phantom power board to feed the 9v preamp?
Thanks!

Jonathon Yi

2/24/2017 11:18:49 am

Built two boxes with these, along with a Cab Sim, and Runoffgroove Tonemender. Worked great! Although I'm clipping a lot in my input. Was wondering if there was a way to add a PAD toggle and/or Ground Lift?

Jonathon Yi

2/24/2017 11:27:33 am

I may have answered my own question about the Ground Lift. Just put pin 1 on a spst?

Jonathon Yi

2/24/2017 02:09:47 pm

Don't listen to me...... Phantom Power comes in from Pin 1 hahaha Don't cut pin 1 =X

Fredrik Lyxzén link

3/6/2017 01:59:01 am

Hi Jonathon,
I apologize for the slow reply. I've been on tour.

It was a long time since I draw up this layout, so I would have to do some research to be able to answer your questions. I suggest that you check out of Elliot Sound page for more info on his DI box. http://sound.whsites.net/project35.htm
cheers / Fredrik

Jonathon Yi

3/6/2017 08:11:14 am

Hey Fredrik,

No problem! I appreciate the reply, nonetheless! Have fun on tour! :D

baouftou

3/6/2017 02:18:19 pm

so anyone actually made a groud lift switch for it??? all i read is that its complex cuz of pin 1 providing phantom power to the circuit.

Jonathon Yi

3/6/2017 04:31:00 pm

baouftou, I just read this:

"The earth lift is only fully effective when the transformer circuit is used, and will prove worse than useless in an active unit."

hahaha "worse than useless in an active unit." Pretty strong emphasis! For what it's worth, I've built two of these and never really needed a ground lift. I just figured it would be nice to have one just in case, but looks like the active circuitry takes care of it haha

baouftou

3/7/2017 01:13:38 am

Jonathon Yi thanks for answering pal!

Well i've understood perfectly the sequence on why we cant ground lift this DI box. Still i'm eager to find a sligtly different solution to it just for the reasons of surviving. "Lets say i went to cover a concert with this and suddenly is starts humming and i have no other DI for backup" I'm dead :P

Let me know if you find anything!

Jonathon Yi

3/7/2017 08:46:55 am

haha no worries! I wanted to put one on there for the same reason! Just for the added comfort. That excerpt from the article discouraged me though... haha :(

I'll post whatever I find, here!

Didier

5/24/2017 10:57:33 pm

As I'm looking to the schematic on http://sound.whsites.net/project35.htm, as I'm saying to me we can lift ground adding a switch on the left down part between VR1 ground pin and the dot right down TL072's pin 4.
On the layboard here, VR1 is absent (as the pad too) but I think we could wire a ground lift switch where "ground" is written.

baouftou

3/7/2017 02:19:24 pm

hehehe. me too!!

You think maybe this with 1/4 watt resistors might give more output than needed?

Jonathon Yi

3/7/2017 02:30:58 pm

Hmm... I doubt it. If anything it might introduce more Noise. I've made two of these so far with 1/4 Watt 1% Metal film resistors and everything seems fine. I remember the volume was at unity, but I built this into an EQ/boost pedal, so unity didn't matter much for me haha

Matthias

3/25/2017 06:36:11 am

Is 4.7 K alright for the LED resistor (I use a standard red 5mm LED)?

Matthias

3/25/2017 06:54:07 am

Sorry, it’s a low current LED. It’s quite bright, but the brightness is OK for me. The question is: Should I definitely go higher than 4.7 K or can I leave it this way?

Fredrik Lyxzén link

3/28/2017 01:43:11 am

Hi Matthias,
If you are ok with the brightness you don't need to change it. Other then having a bright LED it will not be a problem concerning current draw ect, so nothing to worry about. :) cheers / Fredrik

DIDIER

4/26/2017 12:30:34 pm

Hello. I'm looking to build one and I ask me how I could add easily a pad attenuator. Is it useful for active bass or guitar pedalboard ?
Thanks

Fredrik Lyxzén link

5/6/2017 04:29:05 am

Sorry, I don't know how to add a PAD to this specific schematic used for this DI box. I've googled and had a look at other active DI schematic, but found nothing that can be directly applied here.
Best regards / Fredrik

DIDIER

4/28/2017 07:28:46 am

Another question : Can I put 2 polarized capacitor of 47uf mounted +- -+ instead of non-polarized 22uf ?

Didier

5/5/2017 01:06:08 am

The question could interest someone but I found bipolar 22uf.
It's still a theorical question

Fredrik Lyxzén link

5/6/2017 04:20:15 am

In short, yes. :)

Didier

10/31/2017 11:49:55 am

Hello. Is there someone who experience a very low sound with a lot of white noise (and resolve it) ?

Didier

11/1/2017 05:42:07 am

😕 i built another one this morning and i reached the same result : low sound, big noise. If someone could send me a picture of his board to have a look I didn't mistake in a component orientation. Disappointed, really.

Didier

11/4/2017 06:33:29 am

I found on another website that we must use metal film resistors for audio device. I hav some carbon film on my DI Box.
Could it be the reason why ?

Didier

12/4/2017 11:20:02 pm

Another build one and issue is the same. Are you sure that works ?

Tom

9/2/2018 03:09:48 pm

Hey Fredrik, not sure if your still watching this thread but I have a question. If the circuit is powered by phantom power thru the XLR, what connects to the Power LED+ row? Do I run a jumper from Pin 1 row to Power LED+ row?

Active Direct Injection box (DI)

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