Bo Hansén's DI Box using left-over chinese Mic-transformers

[mihi_fuchs]

Hi there,

I just started recently posting in the forum, but as I had quite some time to pass, I started building several designs. One of them was one of the most popular projects - the BO Hansen DI (see the forum thread about the layout: Bo Hansen DI layout and Bo Hansén's homepage: Hansén Audio Gothenburg).

As I had been gutting some mics before I had several transformers of chinese tube mics lying around (T.bone SCT800s). Trying to find a cheap chassis for the build, I stepped over the Millenium DI-E box (11.40 €) which should give a good starting point and additionally the XLR connector is reuseable.

Here is the link to the detailed building thread, a BOM I used for my builds and some bass recordings. As references for the recording I took the Soundskulptor MP573 (Neve 1073 clone) with DI jack and a Samson MDA1 DI Box (transformerless active design). Please do not kill me for my poor bass skills - I know I should practice harder.

https://www.dropbox.com/sh/y0qvfqjwpdb6uqa/AACj8uwmTD88vuMoS_FERyj_a?dl=0
Here are some pictures of the build:











All in all it is a pretty easy and cheap build (11,40 € chassis + ca. 11 € parts by mouser).

Other transformer may fit as well - here are the dimensions:


Last but not least, the design is based on Bo Hansén's DI Box layout and all his hints for the build (see the homepage link above) have proven extremely helpful in finding substitutes for parts and adopting the design to the transformer and the chassis. In addition the included PAD switch was also recommended by Bo Hansén in one of his numerous answers in this forum, as he suggested to use the same as in his API 324 DI input modification (see his homepage again).

Cheers
Michael

 

[Ricardus]

You should label the samples with numbers or something, because now peoples' biases are going to choose their favorite sample, not "objective" listening.

 

[mihi_fuchs]

You should label the samples with numbers or something, because now peoples' biases are going to choose their favorite sample, not "objective" listening.

Hey Ricardus,

thanks for the suggestion. Did it. The solution you can find in the file DI Numbering in the same folder. Let's see if the bias gets less. I think you can hear a bit of a difference, but I was surprised how well the chinese ones performed. But of course that's a matter of taste and also may depend on the source.

 

[Ricardus]

Hey Ricardus,

thanks for the suggestion. Did it. The solution you can find in the file DI Numbering in the same folder. Let's see if the bias gets less. I think you can hear a bit of a difference, but I was surprised how well the chinese ones performed. But of course that's a matter of taste and also may depend on the source.

To be honest I thought the Bo's sounded best. Even with those questionable trafos.

But of course I am a Bo fan, I built 8 of them.

I own some MP573s, too, but haven't gotten around to recording with the DIs yet. I only tested them when I finished the builds to make sure they worked.

 

[mihi_fuchs]

To be honest I thought the Bo's sounded best. Even with those questionable trafos.

But of course I am a Bo fan, I built 8 of them.

I own some MP573s, too, but haven't gotten around to recording with the DIs yet. I only tested them when I finished the builds to make sure they worked.

i had been surprised by the trafos as well ... don‘t get me wrong - i love those two mp573 i bought and built (most probably the best bang for the buck of all my diy projects) ... but in comparison the dis are all very close in my ears ... so maybe this becomes a nice project for all these discarded mic-trafos ... let‘s see ...

 

[Ricardus]

It looks like you designed your own boards specifically for that transformer and for the case you were using?

 

[mihi_fuchs]

It looks like you designed your own boards specifically for that transformer and for the case you were using?

yes, i found the donor chassis to be much more cost effective than starting of with a new chassis (holes alread drilled except the one for the diode, xlr connector reusable). and the transformers were left overs from mic builds. i guess some of us have these kind of transformers lying around so maybe it‘s a good way to recycle them ... but i also posted the transformer slot dimensions in the end of the building guide, just in case you want to do something similar ... i can also check the height in terms of space in chassis and add it. then one can see if it works out with his transformer. i think also other trafos, like cinemag should work as well ... but one can check via the dimensions ...

 

[mylesgm]

Hey, I've got a few of these transformers, any chance you've got some boards left I coul buy?

 

[EvLoutonian]

Hey, I've got a few of these transformers, any chance you've got some boards left I coul buy?

That's the ticket!