Bo Hansen DI layout

[Bo Hansen]

Studio Mollan,

You do not need a ground lift switch in this construction, because it has a "ground loop suppressor" that works well under normal ground loop problem situations.

In addition, the phantom powering systems will be very poor with a ground lift switch, because the negative side must find their way through the power system grounding in order to reach the DI-box.

I think your problem is that your piezo microphones or its connections are not properly shielded.

I guess the hum or buzz disappears when you pull out the input connector from the DI-boxes?

I assume you feed the DI boxes with a stable and clean 48 volt dc voltage.

Of course, if you have hum / buzz problems even when you do not have anything connected to the inputs, then please get in touch with me.

If so, I want to see how the DI-box looks like on the inside, and know exactly what type of external equipment you have connected to the DI-box in / out connectors.

A small comment about the LEDs.

I have repeatedly pointed out that you must use a red LED, to get the best headrom and clipping behavior.
So, do NOT use yellow, orange, green, blue, white or flashing types.
The reason is that the red LED has the smallest voltage drop compare with the others.

--Bo

--Bo

 

[philipNL]

Does anyone have the assembly guide?
https://pcbgrinder.com/download/BODI28/BODI28-assembly.pdf

Its offline

 

[Bo Hansen]

philipNL,

BODI128 was a version of my "Bo Hansen Active DI Box 1975" that PCB-Grinder made on their own initiative , recently published on their web page, but which I thought not coresbond with our DIY projects in this topic/thread .

Therefore, I and PCB-Grinder desided that their version would be removed and the old original card will be restarted by me or any other company that takes over the production and sale of original PCB.
We are working on this right now.

Regarding the old ORIGINAL version's description and advice, please visit my DIY page www.hansenaudio.se/techpage.htm

--Bo

 

[philipNL]

Thanks Bo!
Any idea of when this new original pcb will be for sale?

Thanks!

 

[Humner]

nevermind - asking silly questions, just had a look a closer look as to what this is.

 

[warpie]

After spending a couple of years using this DI I must say I really like it.

However, I have the following "problem/question".

When I record I use pretty much all my mic inputs for mics. I do have spare line inputs in my interface so I was wondering if there's any modification that can be done in order to use this DI with line level as opposed to mic level. Of course the DI would have to be powered by a separate/external Vdc, I understand this 

 

[Bo Hansen]

philipNL,
We can not find "Garber files" to the original PC layout, so we have to redo the layout again, and Soeren_DK doing this right now.
It will take some months before the PC cards are available for delivery again.


Humner,
Sorry, I do not understand your question, do you mean what this DI-box should be used for ?

Warpie,
If you use a 1:1, 5k or 10k to 5k or 10k transformer and run the DI-box electronics with dc-regulated 24 volt that you insert after the two 6k8  resistors and ground, you can get near 1 volt out if you use  high output pickups on the guitar/bass.

Sometimes, there are typically 10 dB gain make up on line inputs, so maybe it will work fairly well.

--Bo

 

[azure skies]

I noticed on the OEP datasheet in the notes they say Do not pass DC through the windings

Is the phantom power typically balanced well enough to not pass any appreciable current through the windings from pin 2 to 3 (or 3 to 2)?

Also, I wanted any advice anyone could give on adding a mute. Bo mentioned having a switch in parallel with the output of the 10uF and ground, with a 100k resistor fixed to ground. Are there any other pointers to making the circuit resilient to "pops" when muting? This is to help protect the PA when connecting/disconnecting acoustic guitars to the DI, typically resulting in very loud pops coming through the system.

 

[Bo Hansen]

azure skies,

If you connect the Phantom powered microphone cable right, there are no dc current between pin 2 and 3.
The Phantom system feed same +48 volt to both pin 2 and 3 split from two resistors.
The minus/ground 48 volt is only feed to pin 1, and this is total isolated from transformer windings.

Yes you can connect a single pole switch after the 10 uF capacitor to ground, so the output signal is shorted to ground in mute mode.
In this case you not need a extra  100K resistor.

--Bo

 

[azure skies]

Thanks for the feedback, Bo.

One other question....

I want to use two of these in parallel for stereo operation. I would like to use an actual stereo plug (3.5mm) as opposed to two mono plugs for left and right. What is the best way to wire for this configuration? Here is what I would gather:

The stereo plug is isolated from the chassis. The left signal goes to one board, the right signal goes to the other board. The sleeve terminal has two wires, one going to the ground of each board. Both XLRs are connected to its respective board as usual, with a chassis connection to each pin 1. Does this sound right?

 

[Bo Hansen]

azure skies,

Yes, absolute right, this connections style will be fine.

--Bo

 

[Whoops]

philipNL,

BODI128 was a version of my "Bo Hansen Active DI Box 1975" that PCB-Grinder made on their own initiative , recently published on their web page, but which I thought not coresbond with our DIY projects in this topic/thread .

Therefore, I and PCB-Grinder desided that their version would be removed and the old original card will be restarted by me or any other company that takes over the production and sale of original PCB.
We are working on this right now.

Regarding the old ORIGINAL version's description and advice, please visit my DIY page www.hansenaudio.se/techpage.htm

--Bo

Hello Bo,
Im sorry I really didn't understand what was the problem with the BODI128,
you mean the BODI128 was a version based on your DI but was not as good as your original layout?

Or that the BODI128 was being sold without your approval, and now it will be sol by you or someone you approve?

Is that I didn't understand what you meant by "which I thought not coresbond with our DIY projects in this topic/thread ",
I have some BODI128 and if there's any problem with the circuit or if the original circuit is different and better, I would prefer to do this projects with your boards.

Thank you

 

[Bo Hansen]

philipNL,
and all of you who are wondering about the same thing.

Here is the story in short, why our original PCBs were removed from the PCB-Grinder's product line and instead replaced by a new PCB and kit, and now also been removed from their products.

From the beginning, the project started with the "original PCB layout" that two guys from Denmark, Soeren-DK and Luny Tune wanted to make a circuit board that suited my DI-box design, and I helped them with this.

Gustav, another Danish guy took on the task of producing and selling this board for a cheap price, and so far so good.

To day, Gustav run his business PCB-Grinder, and have decided to no longer manufacture and sell our original circuit board according to the original PCB layout that corresponds exactly to all this we have discussed in this thread here on the forum, which is now over 100,000 people read and taken note of.

PCB-Grinder decided instead to make its own circuit boards and a complete kit based on my DI-box design.
They also decided to use their choice of transformer and remove the option of the three of me approved transformers which perfect fit the original circuit board.
They have also made all connectors PCB mounted/placed, and this makes it harder to use various types of metal boxes, becauce the new circuit board is adapted best for their own metal box.

I and Gustav have discuss my views on his own initiative and version of my DI-box design, but we can unfortunately not agree and get along.
We decided instead that he will remove everything associated with my DI-box design from his product sortimen, and he will instead makes a completely new own DI-box electronics that does not remind of my design.

I am now developing new original circuit boards, and these will be sold by me or any other chosen person/company who will handle this.
I will return with more information as soon as possible.

Those of you who bought the PCB-Grinder BODI128 pc-cards or kit, and have problems, may contact PCB-Grinder directly for support, I can unfortunately not help you with this, because I have not been involved in their design in any way at all.
(they have done so on their own initiative without my knowledge or to ask me)

Regarding all of you who want to build "Bo Hansen Active DI-Box 1975" with the original circuit board or otherwise, are very welcome  with questions and more, here at this forum thread, and I will help you as best I can, as I have now done in 5 years when this thread existed.

I will also thank Gustav for all those years, he produced and sold our original circuit board, he did a great job and effort.
But unfortunately it was not in sufficient quantity to be profitable, probably this was the reason that he did our DI-box projects in his own way.

Best from
Bo

 

[philipNL]

Thank you for explaining!! 

 

[warpie]

Warpie,
If you use a 1:1, 5k or 10k to 5k or 10k transformer and run the DI-box electronics with dc-regulated 24 volt that you insert after the two 6k8  resistors and ground, you can get near 1 volt out if you use  high output pickups on the guitar/bass.

Sometimes, there are typically 10 dB gain make up on line inputs, so maybe it will work fairly well.

--Bo

Thank you Bo 

 

[Humner]

Thank you so much Bo.

Now I think i got it!

Can someone confirm this is correct for the PAD switch?

I think I will go the self etch route - its hard to find the original PCB's!

I have recreated the self etch layout in my own PCB software to make my own modifications(I'm only using the OEP transformer)

 

[Bo Hansen]

Humner,

Yes, you have get it right. (if the switch is a 3 position on-off-on)

BTW, are you sure you need a PAD on the DI-box input ??

Note, you have use the older schematic, it is better if you change R3 and R4 to 100 K, and C3 to 10 uF.

If you read my instruction on my tech-page www.hansenaudio.se/techpage.htm ,you can find the right tips and build instructions, there is everything you need.

--Bo

 

[Humner]

Hi Bo,

Thanks for your response. You are right, pad on the input isn't completely necessary, I think its more of something to have just in case.  But now I'm thinking to leave it out all together.

The schematic shown is from another member who posted previously. I used it as it was a clear reference to the PAD mod.

 

[Whoops]

Thanks for the feedback, Bo.

One other question....

I want to use two of these in parallel for stereo operation. I would like to use an actual stereo plug (3.5mm) as opposed to two mono plugs for left and right. What is the best way to wire for this configuration? Here is what I would gather:

The stereo plug is isolated from the chassis. The left signal goes to one board, the right signal goes to the other board. The sleeve terminal has two wires, one going to the ground of each board. Both XLRs are connected to its respective board as usual, with a chassis connection to each pin 1. Does this sound right?

I think it's as simple as that!

 

[philipNL]

I've finished building the Bo Hansen DI, but It has some faults. The output is very low. I've to turn the preamp up to 75 db to hear something.
The led does work (3mm red led)
And when I unplug the jack in the input I hear a lot of noise.

Hear the sample:
http://picosong.com/Lt8Y

You hear me ticking on the chassis after i unplug the jack cable.

Im using the OEP transformer.

Does anyone know or can see on my pictures what the problem might be?
THANKS!

Im a first time DIY'er.