Bo Hansen DI layout

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herbejo

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Jun 17, 2015
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Here is my build, while was waiting for the transformer to arrive I used a st ives L10468 as a temporary replacement and to compare to the LL1538. The two transformers sound very different, but I like them both so I think I will have to build another one with the st ives transformer. It could be cool to have both in the same box sharing the same input and being able to blend the two outputs.
 

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Bo Hansen

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Jun 4, 2004
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Gothenburg, Sweden
herbejo,

L10468/VT22670 and LL1538 have almost the same ratio, but not quite, as L10468 has a slightly lower output, but not much.

Have you checked that the L10468 is correctly configured, the normal primary should be in parallel and secondary in series for ratio 1: 4.8, and then it is used backwards in the DI box as 4.8: 1.

I understand very well that the character is different, these two transformers have a completely different structure and material.

Another thing that is important to try is what the square wave response looks like, for example if you use 100 feet cable from the DI-Box XLR connector to the mixing console
1kHz square wave shall not have disturbing overshoot and ringing and not too much slope or rounding in its flanks, this will sounds like a big character difference between different transformers.

I have tried this carefully on the three transformers I recommend and which directly fit on the circuit board, LL1538 behaves extremely well on square wave and the other two very acceptable. (that's why I chose these three as different price options)

There are probably many other around 1: 5 ratio microphone transformers that fix good square wave response, like L10468, but I have not tested this myself.

--Bo
 

herbejo

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Jun 17, 2015
Messages
2
Location
New Zealand
herbejo,

L10468/VT22670 and LL1538 have almost the same ratio, but not quite, as L10468 has a slightly lower output, but not much.

Have you checked that the L10468 is correctly configured, the normal primary should be in parallel and secondary in series for ratio 1: 4.8, and then it is used backwards in the DI box as 4.8: 1.

I understand very well that the character is different, these two transformers have a completely different structure and material.

Another thing that is important to try is what the square wave response looks like, for example if you use 100 feet cable from the DI-Box XLR connector to the mixing console
1kHz square wave shall not have disturbing overshoot and ringing and not too much slope or rounding in its flanks, this will sounds like a big character difference between different transformers.

I have tried this carefully on the three transformers I recommend and which directly fit on the circuit board, LL1538 behaves extremely well on square wave and the other two very acceptable. (that's why I chose these three as different price options)

There are probably many other around 1: 5 ratio microphone transformers that fix good square wave response, like L10468, but I have not tested this myself.

--Bo
Hey Bo,

Thanks for replying, I did configure the L10486 as stated, your website was very helpful for figuring this out. When i build my next one with the L10468 I will do this square wave test to properly compare them. If i had to only have one it would be the LL1538, it sounds so good, but the L10468 has a nice colour.

Thanks for designing such a great DI

-Blair
 

Newmarket

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Oct 10, 2016
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Brighton Sussex UK
Hey Bo,

Thanks for replying, I did configure the L10486 as stated, your website was very helpful for figuring this out. When i build my next one with the L10468 I will do this square wave test to properly compare them. If i had to only have one it would be the LL1538, it sounds so good, but the L10468 has a nice colour.

Thanks for designing such a great DI

-Blair

Depending on what you find with a square wave you might want to consider adding additional termination - R or RC "Zobel" network across the transformer output. (That will be in parallel with the existing pre-amp termination).
 

Whoops

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I would like to build it with some slight modifications:

Hello Low.end.b,
as you want a different custom circuit and more complex than the basic Bo Hansen DI circuit,
you should do a separate thread in "The LAB" section just for your project.

I will help you there, as will other people, but as this thread is only related to the Bo Hansen DI basic circuit I think this might not be the right place to ask and I think you will get more help if you do a separate thread.

Best Regards
 

low.end.b

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Sep 16, 2022
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Brazil
Hello Low.end.b,
as you want a different custom circuit and more complex than the basic Bo Hansen DI circuit,
you should do a separate thread in "The LAB" section just for your project.

Hello Whoops,

Thanks for your input, I'll do as you suggest.
I'm going to delete the message in this post to avoid inconvenience.

Best regards
 

Pete vB

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Jan 5, 2023
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Location
Brisbane, Australia
I have just bought and received 2 x two channel "Bo Hansen" DI boards from Pro Audio GC. I also built up a mono one from them before that, to replace the horrible Behringer stereo DI and did not know they are marketing this without permission! That's pretty underhanded, but does reflect how well respected the circuit design is!
 

Bo Hansen

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Jun 4, 2004
Messages
702
Location
Gothenburg, Sweden
Pete vB,

Thanks for letting me know about this.
I have just sent them an email and requested an explanation why they are using my design and our PCB layout for their own profit without asking my permission.

--Bo
 

donz5150

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Joined
Jan 23, 2023
Messages
6
Location
Jakarta
This year I've been in a few situations where I would have liked a Stereo Bo Hansén DI. As small as possible, and with an optional external PSU if there is no Phantom power available at the venue.
So for Christmas, I did this present for myself:

View attachment 87835

Happy new year everyone, and thank you @Bo Hansen for this fantastic sounding DI Box.
Hi..
thats really awesome built !!
I am new here, and looking for the mono version of Bo Hansen Active Di box pcb
where can i buy it? with the Haufe transformers
thanks
 

Whoops

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Joined
May 9, 2008
Messages
7,322
Location
Portugal
Hi..
thats really awesome built !!
I am new here, and looking for the mono version of Bo Hansen Active Di box pcb
where can i buy it? with the Haufe transformers
thanks

Hi,
as you new here I will let you know an unspoken rule around here,
always read the first post of a thread very well before posting.

The answers you look for are there
 

thelivingroom

Member
Joined
Feb 24, 2015
Messages
5
Another very satisfied builder of this project reporting here. I made a 2-channel rack version in a remote box that I can move around the studio while tracking, and have two more boards stuffed for the future that I’ll be installing in a custom box with 4 reamps (Jensen schematic) and 6 DI’s (4 Cinemag passive and 2 Bo’s) for my control room for mixing and/or tracking purposes. These things sound killer, and are dead silent. Thank you Bo for your generosity and Volker for the PCB’s!

4DFE388B-9B8A-4DC0-A0F8-CA36505E4046.jpeg 9CFECC4F-5350-4DF3-B547-17F47377F4FA.jpeg 331C3BA9-E0B4-4E29-BC8F-54DDEF6B8A01.jpeg B479455B-7D65-4E39-A67C-771E1AA5C793.jpeg EE5B5232-4772-444C-A1BA-549DB65185ED.jpeg ABE8481F-CC0D-4216-BA7E-14D6A49B0B61.jpeg 6E7E8A2C-0C20-48CD-AAFE-2E68973AE719.jpeg
 

thelivingroom

Member
Joined
Feb 24, 2015
Messages
5
It looks really good, congratulations for the build.

What XLR's are those?
I think I never saw those XLRs before

Thanks
Thank you!

The XLR’s are Neutrik Model number NC3MPR-HD. You probably never see them because they’re a bit pricey, but the cost of this project overall was much lower than some of the others I’ve done, so I wanted to splurge a little on something that I thought would look nice since they’re visible haha.
 

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