Bo Hansen DI layout

[00940]

Well, it took a month to get to work (the build itself just took about 3 hours for the pair) but here they are.

No-frills version, transformers are OEP (from Farnell, Canford wouldn't sell to someone without VAT registration), all connectors neutrik and the box is a Hammond 1590C. I might add a 20db pad in the future if the need arises. Construction was very easy thanks to the pcb and the detailled instructions. As usual, the worst part was making the holes for the xlr jack (with only a hand drill and a metal file, yuck). They won't win any beauty contest but they work and that's all I need.

Thanks a lot to Bo for providing both the design and such clear build instructions.

 

[frans]

I couldn't resist to show off my Pirate D.I. - iron is the the Haufe from Volker, board and parts from pcbgrinder. The top is acrylic glass cut by Frank from nrgrecording, laminated print underneath. Box from Hammond.

 

[flaheu]

cool !

Is Bo really looking like that ?
and..........where is sponge bob  ;D ;D

 

[kante1603]

Pipi lebt!

Udo ;D

 

[Bo Hansen]

Sure, it's me as a young hippie with long flowing hair and beard, now I'm old and bald with stubble.

Best from
Bo

 

[jasonallenh]

Hi guys

I have built two of these DIs, and I love them very much! Both have been working without a problem, so I decided I wanted to rack them and maybe add two more into an old 1U chassis I never used. I got the first two mounted (keep in mind that in their own individual enclosures, they wore working fine), and now there appears to be some strange ground noise. I haven't done anything different from the grounding scheme mentioned on Bo's page, I just took the two circuits and put them in the same box. When I used two separate sources, there was no problem, but when I put the left and right channels of a stereo keyboard into the two inputs on the box, i got the noise.

Are there any additional considerations I need to observe, or should my 'dual mono' style unit work as planned?

 

[kante1603]

A pic might help,maybe non-isolated jacks?

Just a thought,

Udo.

 

[jasonallenh]

Alas, I am not near them... Nor will I be until the weekend :-\

I DO know the jacks are isolated per the instructions, remember, the two individual DI circuits worked until I put them in the same case. I Should mention that I've used the Jensen JT-13k6-c. If I made a mistake, it would likely be related to that, because all the jacks are isolated like they were supposed to be.

 

[Bo Hansen]

jasonallenh,

Normally it should not be any problems with ground loops between the equipment in the studio and control room, even if two or more DI- boxes mounted in the same metal housing.
But it is important that you use insulated tele-jacks, and followed my grounding instructions.

A other thing you must need to know is that the ground suppressor in this DI-box works the same way as a ground lift switch does in other types of DI-boxes, meaning that it breaks up the ground system between DI-boxand mixing console, but it is still a normal grounding system between the instrument input and the amplifier output jacks.

For this reason, you can get ground loop problems that result in hum or buzz if you for example connect two amplifiers, one to each DI-box amp output jack, and if these amps have earthed mains cables connected to earthed wall sockets.

Similar problems can occur if you have mains connected effects devices or synthesizers connected to the input jacks.

But if it is important for you to use multiple monitors/backline amplifiers connected to the DI-boxes in the same housing, you can add a similar ground loop suppression circuit as you can see between the XLR connector pin 1 and PC-card ground rail, and do same trick for the ground sleve terminal on the amp out jacks.
(use all four components, 2x 1N4004, 100 ohm, 0,1 uF)

--Bo

 

[jasonallenh]

Bo!

Thanks so much! That's a lot of useful information. I'll put it to good use.

 

[anjing]

My hat to Bo!

  Just build one Di with the pcb i got from Gustav. It sounds stellar trough Ian's eztube preamp.

Great thanks for making this available.

Regards,

Pierre

 

[Esoterimix]

Anyone got some of these PCB's in the US? I don't really want to etch my own, call it laziness ::smile::
I would like to get my hands on a couple of these if possible... Or even if someone is down to etch one for me.

Before you say it, I know I could use a perf board or something of the like, but screw that... I want these to look professional. I really like the concept of the D.I. and I'm trying to build several different styles of D.I. after this one, it's on to a Tube based D.I. (like, maybe, REDDI)... Send me a pm or e-mail me at Esoterimix [at] gmail [dot] com

Thanks in advance!

 

[Bo Hansen]

Esoterimix,

I am sure that our PC-board guy Gustav does not have any problems to quickly and easily send the original PCB directly to the U.S.

Here is the direct link:
https://pcbgrinder.com/index.php?route=product/product&path=59&product_id=58

--Bo

 

[Esoterimix]

Just got two boards from Gustav in the mail today... Very excited, getting the BOM all sorted. I'm already rolling designs for the outside of the box in my head.. Should be interesting... This will easily be the most painless project on the work bench. It really is awesome to have people like Bo and everyone who makes this community possible. p.l.u.r.

 

[Esoterimix]

I have . question... I saw the dB pad schemo someone posted and it had an RC for the -10 I believe...just curious, but would that basically act as more of a filter than a pad?
the cap shown os 18 pf  with a large resistor, does the last on that just work out to be avalue that pretty evenly pads across the necessary frequency band width because I thought there would be a slope at like 6db per octave....
also, if I.built the pad (on a eurocard I sized with a dremel) could someone check the wiring?

 

[Bo Hansen]

Esoterimix,

A 2.2 meg resistor connected in series with the input of my DI box that has an input impedance/resistance of 1 meg will attenuate the signal 10 dB.

But since this is a high-ohm voltage divider it also provides a treble loss.
This is corrected with an 18 pF capacitor in parallel with the 2.2 meg resistor so that the PAD will get flat response again.

If you connecting a 330 kohm resistor after the 2,2 meg/18 pF to ground, you get an additional 10 dB of attenuation, which in total will be 20 dB.

You can find a complete solution here: http://www.groupdiy.com/index.php?topic=36569.msg467685#msg467685

But consider that this DI box can withstand lot of level on the input before the electronics choke/clipping, so if the signal to the console's mic input is too high, and if you have PAD on the console, use that instead, it usually works well many times.

--Bo

 

[Esoterimix]

wonderful. thank you for the quick response. I found the schematic already but the cap seemed pf however, you've cleared it up. I doubt I'll need a pad anytime soon, but I want the practice. gonna use a dremelry tool and eurocard to make it. Ill post pictures when i get that done....

gotta say, Bo, the box sounds fantastic for both live and in recording applications.  thanks.

 

[dribro]

hello everyone

thanks a lot to Bo Hansen and others for making this possible. The 3 units sound good, even the pikatron revealed a great tone !

 

[kante1603]

Nice colours,congrats to yout builds!
Yes,pikatron are good transformers indeed.
But why did you make a groundlift?

Udo.

 

[dribro]

thanks!  yeah,  I know it defeats the loop suppressor feature... but as I intended to use all the hardware of the thomann boxes, as it doesn't have plastic connectors for the TRS's, as safety measure I left and ended up using the switch. Oh well maybe I'll change it later. Pretty neat little things!