Bo Hansen DI layout

[RuudNL]

I prefer to use a jack that shorts the input when nothing is plugged in.
What you hear is an 'open input'. You probably did not have the box closed when you made the recording. (=Hum)
Or you did not connect the metal of the enclosure to pin 1 of the XLR connector.
The level (-75 dB) is a bit strange, although I don't hear any distortion or other problems.
You could measure the voltages on the collector and emitter of the transistors and let us know, that will give an indication about the correctness of the circuit.
The output level is determined by the output level of the pickup coils in your guitar, and the step-down ratio of the OEP transformer.

 

[philipNL]

Hi Ruud,

Thanks for your reply and nice to see you here. You repaired my Neumann u87ai which my dad brought to you in Fryslan

I didn't have the box closed indeed and I didn't connect the metal to pin 1 of the XLR connector.
I did connect a wire from the pcb where it says 'chassis' to a screw in the metal enclosure. But I didn't do anything with the xlr pin 1.

So If i'm not mistaken. I need to connect two wires from the "chassic" on the pcb board. One to the XLR connector pin 1 and one to a screw in the metal enclosure. (which i already have).

Is that correct?

Thanks for your help

 

[Gustav]

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

Just to clarify, since I am getting mails about this.

I get permission to sell the projects when I make boards for others, so I saw no reason to involve Bo when doing my own take on this, in my view,  generic design.

After being contacted by Bo, I realised I never talked to him direct and only Søren/Luny when starting the production, I therefore respected Bo's wish to discontinue the new board rather than continue a project managed by a third party.

There were clear reasons for my decision to evolve the project, and for the same reasons, I am currently working on my own board. There will be no reference to Bo's name or the 1975 dated project on this, but I will not restrict myself from using protection diodes or filters or other generic design tools, just because they were used in Bo's design.

So no, I no longer sell the BO DI board, and dont bother mailing me to ask if I still have some in the drawers. I will leave this to someone else and focus on a new design going forward.

All the best

Gustav

 

[RuudNL]

@philipNL: if you take a closer look at the PCB, you will find that the point 'Chassis' is connected to pin 1 of the XLR connector.
So in fact it doesn't matter, the connection is the same!
Closing the metal box will make a big difference in hum, because now (with the box open), the unshielded wires act as an  'antenna' and will pick up all electric fields in the neighbourhood of the DI. Especially because the input impedance is very high. (1 Meg.)
I suppose the hum and noise will stop at the moment you short the input.
For this reason I use jacks with a contact that closes when you pull the plug, so that the input is shorted to ground.

 

[philipNL]

Hi Ruud,

Thanks. I will try that.

Do you have an example of a jack that has a contact that closes?

Thanks!

 

[RuudNL]

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

 

[philipNL]

Thanks.

The DI is working but still very low output.
I recorded a sample, Bo Hansen DI vs. Apogee Duet DI.
The Bo Hansen needs +75db and the Duet only +13db.

Also quiet a sound difference. Is the Bo Hansen supposed to sound like this? (played with stratocaster).

http://picosong.com/LDdW

Thanks

 

[RuudNL]

It would help if you could measure the voltages on the collector and the emitter of the transistors.
This would give us a good impression if the circuit is working correctly.

 

[philipNL]

I measured some stuff mentioned on the Bo Hansen page.

Connect the DI-box XLR connector to a mixer or preamp mic input with true 48 volt phantom powering.
If the LED is used and it light up, this is a first sign of health. (note: CHECK )

Use a digital voltmeter in dc mode and connect the negative test cord to the input jack ground and the positive test cord to the junction av the two 6,8k resistors, or the long leg of the LED if this is used, or the link if the LED not used, and here you should measure +24 volts, +/- 1 volt, if everything works ok.

The next measurment is to check symetrical clipping and headroom.
Move the positive test cord to the junction of 3,9k resistor, 10uF capacitor positive end and emitter on BC560 transistor, and here you should measure around +12 volts, +/- 0,5 volt.

I get different readings. What could be the problem? Will that explain the low output?

 

[philipNL]

Anyone?

 

[audiophreak]

  ... looks like  maybe only half phantom power getting to circuit  ??  check xlr connections / wiring ???

 

[philipNL]

The voltage between XLR pin 1 to pin 2, and pin 1 to pin 3 should be around 36 volts, so this is quite ok.

I only got around 25 volts. Is that were my problem is?

 

[philipNL]

Well, problem solved for anyone who might run into the same problem

I checked all the resistors and they seemed fine. So i swapped out a capacitor for a new one and now it all sounds wonderful.

Problem solved
A bit lucky, but hey.

Sounds really awesome with bass.
http://picosong.com/L7ec/

THANKS BO!!!!

 

[philipNL]

 

[philipNL]

8)

 

[philipNL]

;D

 

[philipNL]

 

[RuudNL]

Do you have a FPD file available for the front panel design?

 

[philipNL]

Hahaha

 

[rockinrob86]

I am working on a veroboard version of this circuit (Thanks Bo!) and am running into a bit of an issue...

I managed to install the transistors backwards, but now I have the circuit squared away.

However, I am measuring 45 v at all of the above test points, including E on the BC560.  Does this sound like the transistors blew?  I have only ever worked on tube stuff and a few simple fuzz pedals, so I'm still learning all these transistor troubleshooting tips