Bo Hansen DI layout

[Bo Hansen]

Treb,

If it is a normal 4 mm red LED, it shall shine quite bright, if every thing else is ok.

But if you have chosen a special LEDs with integrated series resistor, then it will light dimly, and the DI-box electronics will get too little voltage feed.

--Bo--

 

[Treb]

Thanks Bo,

I did some probing:

input ground -> LED :  25.1 volts (+24 volts, +/- 1 volt)
input ground -> junction of 3,9k resistor etc. : 11.56 volts (+12 volts, +/- 0,5 volt)

Everything within spec I guess,  must be the LED. As fas as I know it's a bog standard LED. Perhaps it's because I'm so used to those super bright blue LEDs...  :-\

Attached is the Front Panel Designer file for those wanting to use it for their own purposes, just rename the extension to FPD.

 

[Treb]

Gut shot before I close it again.

 

[Bo Hansen]

Treb,

Very nice job.

--Bo--

 

[Treb]

Thanks Bo! I wanted to have the front panel lettering filled in with yellow paint. Blue and yellow to pay tribute to its Swedish origin. Too bad Schaeffer couldn't do it. I did it myself with a LacquerStik. The Swedish design, the DIY aspect and the blue/yellow colour combination brings about a kinda IKEA-vibe. ;-)

I haven't heard it yet as I'm missing some plugs and  cables to hook it up... Will report back.

 

[Potato Cakes]

A couple of quick notes for the peoples looking to build these sweet little DIs:

The Sowter 9045's sound phenomenal on bass. The data sheet they published on their site shows it nearly flat all the way down and pretty much all the way up. At least in the live environment you can instantly hear the not only all the low notes but significant clarity of the notes over standard fare DI's. I've lent one to a friend for a session he was playing bass on and he told me he got many compliments from the engineers for the sound they were getting with this DI paired with the Sowter. However, one must be aware that it is a very large transformer, and it will work if you are planning to make compact versions of this DI.

The CMO-5/200CT that is listed on Bo Hansen's site has been replaced by the CM-9711. I used this one for a pair and lent it to an engineer and he randomly used it to record keyboards and he was very happy with the results. The idea was to get it to get instruments to cut a little more in a mix as Cinemags in the passive DI's have worked well for this on acoustics in a live setting.

I still haven't tested the ones I built with Carnhill transformers. Hopefully soon.

Thanks,

Paul

 

[Erazorblade]

Hi guys,

excuse me for the maybe inappropriate question, but where can I order the pcb's since the link in the 1st post seems to be broken?

Thank you very much.

 

[Treb]

Volker sells them. He's known as [silent:arts] on the forum. Try reaching him by PM.

 

[[silent:arts]]

White marked link is working again  8)

 

[Matt55]

Hello Bo,

I am looking to build 2 of these for an acoustic guitar, 1 to use, 1 as spare (also I will have a stereo pair at that point). I have a couple of questions that would be good if you could answer

1) Is the Lundahl LL1538 worth the extra money over the Haufe ST8456 and what are the sound/sonic differences between the two models?

2) What is the hole size and spacing between the holes on the pcb for the xlr, input and output. I was thinking about using terminal blocks or connectors but to order I need to know the above measurements.

I was going to use the mouser bom which seems to contain most other things needed for the build.

Thanks for your time and effort on this project much appreciated

Regards,

  Matt

 

[[silent:arts]]

2) What is the hole size and spacing between the holes on the pcb for the xlr, input and output. I was thinking about using terminal blocks or connectors but to order I need to know the above measurements.

2,54mm

 

[Matt55]

Much appreciated, Thank you Volker

 

[Treb]

1) Is the Lundahl LL1538 worth the extra money over the Haufe ST8456 and what are the sound/sonic differences between the two models?

Worth the money is something only your ears can tell. As always the law of diminishing returns applies here too.

Regarding the Lundahl:

Lundahl's transformers are extremely neutral and clean, with no ringing or overshoot. (may sometimes be too good to be a transformer)

Haufe ST-8456 is a very nice transformer, but Lundahl LL-1538 is a bit better, and LL-1538XL (extra lardge) have a bit more headroom in the low end.


I have done some tests and compare Lundahl LL1538, Haufe ST8456 and Walters OEP A262A3E, in my DI-box circuit.

Lundahl and Haufe have near same behavior from 100 Hz and up, but Haufe are a bit better in low end small signal distortion, and Lundahl have lower distortion in low end near saturation point.

Both have a very good square wave response, and have 14 dB loss with 1 kohm total load.

OEP have approx. 10 times higher distortion from 100 Hz and down, and have also higher distortion in the high end, but have ok square wave response, slightly rounded, with out ringing or overshoot.
Because the 6,45:1 ratio, it have 16 dB loss.

All three sounds nice in my DI-box, but Lundahl LL1538 are still the best with a steady and clean low bottom and a fast and clear high end.

--Bo

It's all in this thread. Do read it all, lots of good info! Good luck.

 

[Matt55]

Wow thanks Treb!!!

I think I am going to go with the Lundahl. I actually did use the search function at the top of the page but I didnt see that post...

Maybe that info should be added into the page 1 post so that others can read (I know we should read all 38 pages but...) Its valuable info that can be used when making the transformer decision!

Thanks, Matt

 

[Treb]

Bo's comments about the transformers isn't from a single post. It's what I cobbled together from's three (four perhaps) of Bo's posts. I did a search for Bo's posts... 

All 38 pages? That's nothing! If you ever want to make something like a Millett Starving Student (468 pages), a Pass B1 preamp (405 pages) or a Pass F5 power amp (1503 pages, gulp!) you're in for a treat!  ;D

 

[Bo Hansen]

Treb and Matt55,

Thank's for you reminding me,
I will add the info on my DIY page as soon as possible.

Please read my DIY instructions on www.hansenaudio.se/techpage.htm where you will find the most important about component selection, construction proposals and test instructions.

--Bo

 

[Matt55]

So, I got all the parts together today and finished a stereo pair. Both worked beautifully at first switch on!

Built with the standard BOM, Lundahl LL-1538 , red LED and the Hammond 1590-TBK, with all inputs and outputs mounted on one side (its tight which is why I guess not many people chose this route but possible) because it suits the way I set the stage.

So I tested both by just listening to them over my pa in my front room while my brother played away on his Yamaha CPX900. Both sound beautiful and add a musicality not found when the guitar is plugged directly into the mixer via 1/4 unbalanced jack. The high end is smoother out but more present with that classic transformer sound, and the bass is rounder/fuller. Definitely very pleased and cant wait to use them at the next gig. Very pleased

Thanks to Bo, for the great design and clear instructions and thanks to Volker for providing and supplying the PCBS!

Thanks,

  Matt

 

[Treb]

So, I got all the parts together today and finished a stereo pair.

You know the drill, pics or it didn't happen... 

 

[btwester]

Hi everybody, my first post in here!

I've built a couple of these things before, one with the 1538 and one with the OPA and can hear the possibilities for different applications. 
Due to some earthing issue (my guitar strings touched a metallic lampshade) one of these fried, or the pcb-traces fried pretty much, the trafo reads good. Just glad it protected my computer and mixer, so now I'm building a couple more.

While I can build these upon instruction, my understanding of any circuit topologies is pretty rudimentary. I've heard these things about getting more mojo with choosing certain components for different applications, like using carbon-resistors in some tube guitar amps circuitry or to get a more hifi-sound using polypropylene caps instead of polyester.

So here lies my question for this particular application, Mr. Hansén recommends to use either polyester or polypropylene caps for this on his tech-page.  Everybody seem to choose the polypropylene ones but would choosing for example a Nichicon XY-type or even  Mustard-cap, both which they recommend for "vintage"-style circuits have any impact on the sound, and I know were talking about some very miniscule nuances or responses here? I am  guitarist and don't really look for Hifi, but charming distortion and saturation

Thanks

-btwester

 

[Treb]

I have a suggestion for a PCB revision, should it ever happen. Why not add test points to the PCB?  This way it's easy to perform the two tests described on Bo's techpage. With plated through holes on the PCB the tests could be performed both sides of the PCB.
Or why not add a possibility to hook up 48 volts externally from a suitable PSU? This way you could use the DI to plug into a non-phantom powered balanced input.  Just a thought...