Behringer B2 Pro Electronics upgrade

[micaddict]

What IYO is wrong with the headbasket shape?

 

[ln76d]

IMO it's just ugly
One have to round top, second (beyerdynamic type) i associate  with the coffin.
Same body with coffin type headbasket was used also in BPM microphones.
Only NT2 was decent looking from that type of body.

 

[micaddict]

I see.  ;D
Practically speaking, it's not too small, it's tapered and it has two layers of mesh; one coarse, one fine (which I like).
But next time I'll turn off the lights.  8)
That's what Elvis did when he recorded "Are You Lonesome Tonight?" Better for the atmosphere ...
It was so pitch dark that he bumped into a stand or something of the kind during the last seconds of the recording.
Clearly audible at 3.02:
https://www.youtube.com/watch?v=9XVdtX7uSnk
Didn't stop it from being a monster hit.

 

[user 65018]

Here's next step - measurements with fluke.

Try to find most matched 470nF and 68uF caps.

Measure HFE of each transistor.  Take a sheet of paper and note value of each.
Overall we are looking for highest HFE, you need to find also matched HFE between one 2n5087 and one 2n5088.
If you will find it then also choose other two 2n5088 with highest HFE, no need to match it.
Q1/Q2 is pair of 2n5087/88
Q3/Q4 two other 2n5088 with highest HFE.
[/quote

ok! i did found a  pair of 2n5087/88 close value and two 2n5088.

 

[ln76d]

Here's schematic for the rest of basic modifications.
Compare it to the original wiring on the left.
You need rewire two switches - polar pattern and -10dB.
If there's some pin of the switch permanently connected with the track on the PCB, cut it.

 

[ln76d]

In reply to PM from Ponchampa.

Here's some part of connections on the small board, remove these which are marked with red X.
First desolder switch and cut two traces, one on the top of PCB, second on the bottom.
post new pic of "black box" after you removed 1nF capacitor and 1G resist

 

[micaddict]

I'll add that there are two (main) versions of the B2 Pro. Earlier ones have a detachable head; later ones don't have this.
Pictures in reply #3 here:
https://groupdiy.com/index.php?topic=50197.0

FWIW

 

[user 65018]

Hi!
Here are some more pictures.

 

[user 65018]

more

 

[user 65018]

more

 

[user 65018]

more

 

[user 65018]

more

 

[user 65018]

Hi!
I did removed green wire  was connected to PAD switch and aslo cut solder jumper in between pin . I did check with multimeter to make sure is disconnected.
Green Wima  270 removed.
PAD switch is now act like two ways switch.


Thank you.

 

[ln76d]

Great!

Remove three marked green wires, check with multimeter is it continuity between four points marked with violet arrow.
Last problem is that i don't see connections between the bottom of "black box" and both PCB.
Could you unscrew that and make some pics?

 

[user 65018]

Hi!
Here is another picture .
I did check for continuity on four points , yes they are connected.

Thank you.

 

[user 65018]

Hi!
Here are some more pictures.


Thank you.

 

[user 65018]

more!

 

[user 65018]

More!

 

[user 65018]

More!

 

[micaddict]

We're not afraid of pictures.  8)