Bo Hansen DI layout

[Bo Hansen]

Paul,

The most compact box where the DI box all parts fit, is probably the "Deltron" box you can see on my tech page www.hansenaudio.se/techpage.htm
But it is slightly more complicated to assemble with spacers for the pc-card and some few things.

The other Hammond box on my tech page, is available in a lower version, where all the parts fit, and in that way it becomes much smoother.

--Bo

 

[Potato Cakes]

Thanks, Bo!

I didn't see that info at the bottom of the page. I'll mess around with both and see what I can come up with.

Thanks!

Paul

 

[untune]

I tried joining a few weeks ago to ask Bo a question but couldn't get my account here approved...  He kindly answered by email and in the meantime I built the DI vintage style, on tag board with quality components and Sowter transformer...

 

[OhRats]

Hi all,

I'm about to build the DI (waiting on PCB, and need to order a few more parts) and I have a few questions.

1.  Is there a good alternative to soldering the transfo directly onto the PCB?
I'll be using the OEP transfo.  So not too worried about damaging it.  But I'd be glad to have a straightforward way of swapping transfos in and out.  I will want to try out other transfos eventually, and I would be glad to have the option of going back and forth between them without building multiple boxes.

2.  I'm interested in using molex type connectors to connect the jacks and led to the PCB.  I'm not sure which specific ones fit the pcb, and which type is best for this kind of project.
The molex online catalogue is not exactly helping..
I normally solder jacks/leds to my boards.  But for this particular project I'd be glad to have a cleaner way of connecting/disconnecting the board and the box.)

Thanks a lot!

 

[Bo Hansen]

OhRats,

The circuit board is specially made for this DI box, and built in such a way that everyone is able to mount the components on the easy and safe way.

The safest way to mount the transformer is on the board, there are exactly matching holes for all three transformer types.

The PCB solder connections are standard hole spacing, so there are many suitable connectors and screw terminals that can be used, but the best is to solder the wires directly onto the card.

--Bo

 

[OhRats]

Thanks so much Bo. 

Will follow your recommendations

Can't wait to put this together!

 

[OhRats]

1/4" Jack with break switch, like the ones produced by Cliff (CL1160A)  or Neutrik
The good news is: they are cheap!

Another noob question, apologies.  I understand I need to avoid a grounding connection between the TS jacks and the enclosure.  Following the above recommendation I got a neutrik NMJH4HC-S as a shorting input jack.  (Info on Neutrik Website: http://www.neutrik.com/en/audio/plugs-and-jacks/m-series/nmj4hc-s) (I now realize the NMJ4HF-S also allow for shorting. ) 

Issue is, the HC-S features a chrome nose - with plastic washers.  Unless I'm mistaken, it looks like with a male jack plugged into it, there is possibility for contact between the threads around the *barrel* of the nose and ground (with the male jack providing the connection between the ground lug and the barrel.) The contact point would be as pictured below.)

Am I wrong to assume that the chrome nose makes the part inappropriate for this DI box?  If so, is there a simple way to prevent the barrel from forming a connection with the aluminum enclosure?

Much thanks again!

 

[rockinrob86]

I recommend ordering plastic cliff jacks for these - works perfectly in mine and they are good quality jacks - and it makes the grounding a no brainer.

 

[Bo Hansen]

OhRats,

Sure, Neutrik version works, but it is important that the insulation washers work properly.

Those jacks I recommend is Cliff Plastic, Type CL-1160-A, S2 BNB.

--Bo

 

[OhRats]

Bo, so it's worth at least testing the neutrik?  I'll drill the enclosure and mount the neutrik with its insulation washers, and test whether there is any connection between ground and enclosure with my multimeter.

Thanks so much for the replies!!

 

[Whoops]

Am I wrong to assume that the chrome nose makes the part inappropriate for this DI box?  If so, is there a simple way to prevent the barrel from forming a connection with the aluminum enclosure?

The chrome threads inside of the plastic barrel, so the outside part that will touch the metal hole is just the black plastic,
It's fine.

 

[OhRats]

I finished the assembly and the DI isn't working as expected.  The voltage tests are off.  Using a passive electric guitar, I'm also getting a lot of clipping through both outputs.  If I understand the circuit correctly, that would suggest that the clipping occurs before the transfo. 

Any pointers about what best steps to take to troubleshoot would be much appreciated. 


********

Here are the voltage test figures:

- 21.1 V at the link(led)/6.8k resistors junction.
- 9.4 V at the BC360 emitter/3.9k resistor/10uF+ junction. 

(I don't have a device with true 48v phantom power.  The above figures are from a device with 47.1v phantom power.  With a lower phantom power voltage (45v).  The 9.4v figure stays the same.  The voltage at the link changes a bit: 20.8v.)

 

[Bo Hansen]

OhRats,

Have you built the DI-box on the original PC card or otherwise?

There are lots of people who have experienced similar problems here in this thread, when they got together the DI box for the first time, and of course there is something wrong they have done.

For example, turned a transistor wrong, using transistors with the wrong pin-out, or changed the location of NPN/PNP, wrong value of a resistor, reverse mounting of electrolytes or LED/diode, used an odd type of transformer which is connected wrong, etc.

So check your build again and again until you find the error, and please read the previous posts on this thread for more tipps about your problems.

Regarding your measured voltages.
My recommended voltage values ​​shall be reduced in the same propotion as your phantom power is less than 48 volts.

--Bo

 

[OhRats]

Hi Bo,

You were spot on.  When building it, I didn't notice the note on your page saying that 2n2904/2n2906 have a different leg order than BC550C/BC560C. 

With the 2N290x layed out correctly it sounds fantastic - and dead quiet, as others report.

Thanks for sharing your fantastic design and for your help! 

 

[Bo Hansen]

OhRats,

Nice to hear that you succeeded with your DI box.
Hope you will enjoy it.

--Bo

 

[OhRats]

Have been enjoying it every day since I built it!!

 

[Whoops]

Yeah it's a 125b size that i jb welded the screws and standoffs inside. Got it from pedalpartsplus.com for like $8.

I'm not sure why there's no ground issues but i like it. I'll finish my oep one tomorrow and post more sound clips

There's no ground issues with the setup that DI was tested.
Take it on the Road an soon the ground issues will appear.

Like Bo said many times, the isolated jacks are part of the circuit and are needed to made the ground loop suppression circuit work.

 

[Bo Hansen]

This DI box have a "practical and intelligent ground systems" which in most cases takes care of itself.

The metal box/casing is grounded in the XLR connector pin-1, which is the balanced signal ground system that goes to the mixer or mic preamp.

The DI-box input and output jacks that will be in contact with the guitar, keyboard, pedals and amps, who may have contact with each other via the signal ground and mains protective earth, is fairly well insulated through this DI box built-in "ground loop suppressor"

And for this reason, these jacks are of insulating plastic type, to be insulated from the metal housing, which is very important.

So in this case, a "ground lift switch" is not needed under normal circumstances, when ground/earth problems can arise in different situations on stage and in the studio.

Note!
The DI-box "ground loop suppressor" can of course not take care of grounding problems that occur between the guitar amplifier and effects, but will taking care of ground-loops that could arise between the guitar amp/effects via the DI-box and mixing console.


But, as already noted hear many times, it is important to follow my building instructions on my web site www.hansenaudio.se/techpage.htm
there you can find all the tips about good choice of jacks and the proper ways to ground the metal box and much more.

--Bo

 

[Potato Cakes]

There's no ground issues with the setup that DI was tested.
Take it on the Road an soon the ground issues will appear.

Like Bo said many times, the isolated jacks are part of the circuit and are needed to made the ground loop suppression circuit work.

I actually use these DIs exclusively on the road if I am mixing and for any TV show where my artist is performing  for the broadcast audio and I have never had an issue where I needed a ground lift. I've built these with Haufe, Sowter, Carnhill, and Cinemag transformers and all have noticeably if not significantly sounded superior to the usual assortment of DIs sent out with a mic package. If there was any sort of unwanted noise it was because of single coil pickups near moving light fixtures, which was minimal at best. If the grounding scheme is followed exactly as Bo said there shouldn't be any issue with the audio, although most back line techs I know blame the audio department for noises in their rigs...

Thanks!

Paul

 

[pablobolche]

This is my self etched Hanson DI...
I use it live and always good......
I use plastic jacks and have had no noise issues...
I use oep xfos without the can so my enclousure gets pretty small...11 cm x 6 cm x 3 cm

Thank You Bo!!!