GROUP BUY: Universal Audio 176 - a 100% faithful recreation of a legend! CLOSED!

[Potato Cakes]

I've resoldered the OB2's socket and checked it many times.. The C10 (I guess you mean it namely) is Mundorf Supreme silver oil 0.1uf.

It's apparent that the OB2 socket is soldered correctly and the tube itself is working as the filament lights up with no 6BC8 installed. The issue more than likely is on the way from V6 to V1.

Thanks!

Paul

 

[Greebok]

Thank you Paul, I'll check again (though this build make me a paranoic.. I already don't trust myself  )
Can anyone confirm that the latest layout v1.12 is really correct?

 

[Potato Cakes]

Thank you Paul, I'll check again (though this build make me a paranoic.. I already don't trust myself  )
Can anyone confirm that the latest layout v1.12 is really correct?

The latest layout is correct.

 

[Greebok]

Paul, could you also comment this please:

"I have the following observation: after inserting the 6BC8 back the OB2 works for several seconds and then fades away.."

 

[Potato Cakes]

Paul, could you also comment this please:

"I have the following observation: after inserting the 6BC8 back the OB2 works for several seconds and then fades away.."

Same reply as before. Something is loading down the voltage from OB2 to 6BC8. You'll have to test the path from V6 to V1 as compared to the schematic and test all the connection points of the components involved.

Thanks!

Paul

 

[Greebok]

Something is loading down the voltage from OB2 to 6BC8.

Thank you Paul. The problem was the R43.
Warning! For those guys who's going to use Ohmite resistors: be carefull, it's easy to damage its windings (see the photo below)..

 

[Greebok]

Now I can't get proper(clean) compression on 8 and 12 ratio's. In these modes the signal becomes distorted..  ???
Frankly also I don't hear any difference if I change "attack" and "release" position.. I seems like compression doesn't work as it should (though the unit sounds well).

AND the VU meter almost doesn't show any activity. In GR mode it stands in zero position when the unit is ready, but the arrow does not move left (even due ti high level of incoming signal),  in contrary - it slightly moves right  ) (the same picture in the other modes - the arrow just slightly moves right) .

:-[

Do all 6BC8's have microphonic effect?

 

[Greebok]

The latest layout is correct.

I'm afraid it's not ..  ???
If you connect your wires to the switch/pot as on the layout (as I did on the right side of the picture) it will not correspond the actual schematic.

 

[Greebok]

According to the schematic the attack switch-pot should be wired this way:

 

[Potato Cakes]

I'm afraid it's not ..  ???
If you connect your wires to the switch/pot as on the layout (as I did on the right side of the picture) it will not correspond the actual schematic.

That depends on the model of the switch and your perspective of viewing it. You have do some testing to make sure the correct side goes to ground when compared to the schematic. I did a lengthy write up on all of this and much more when I was posting about my build experience, along with a follow up summary. It's all in this thread.

Thanks!

Paul

 

[Greebok]

Thank you Paul.

Despite of what you were talking about earlier regarding the ratio switch, the latest layout v1.12 still left with mistakes. So I trusted it without checking schematics (but I definitely should not). Now my 176 works properly (I hope so  8)).

As for fine tuning - I preferred to adjust it using my ears since suggested methods don't give best sonical results.. Could anybody share your experience in fine tuning of 176s please?

 

[Potato Cakes]

Thank you Paul.

Despite of what you were talking about earlier regarding the ratio switch, the latest layout v1.12 still left with mistakes. So I trusted it without checking schematics (but I definitely should not). Now my 176 works properly (I hope so  8)).

As for fine tuning - I preferred to adjust it using my ears since suggested methods don't give best sonical results.. Could anybody share your experience in fine tuning of 176s please?

My apologies. I thought all had been corrected with the latest wiring. Like I said, I did a full write up a while ago that mentions the things you found, but I thought the new layout corrected all of this.

I measured the voltages on either side of the plate and cathode balance pots and made sure the voltages were identical and that seemed to give me great results.

Thanks!

Paul

 

[Greebok]

My apologies. I thought all had been corrected with the latest wiring. Like I said, I did a full write up a while ago that mentions the things you found, but I thought the new layout corrected all of this.

Unfortunately not.. so it still may mislead the people..

I measured the voltages on either side of the plate and cathode balance pots and made sure the voltages were identical and that seemed to give me great results

Paul, could you share your measurements and specify the exact points please?

 

[Potato Cakes]

Unfortunately not.. so it still may mislead the people..

Paul, could you share your measurements and specify the exact points please?

You're measuring the voltage of CW and CWW with regards to the wiper for each pot, so you're voltage will vary from mine. The idea is make sure both sides have the same voltage. I don't know if the this is the proper method for setup, but both of mine behave the same and seem to work correctly as I use them all of the time. Again, this is all in my build summary.

Thanks!

Paul

 

[Greebok]

Hey Paul,

could you tell me please? Is 25k potentiometer on "attack" is really enough? I'm trying to notice any difference when I'm turning the attack knob but I don't hear it.. I seems like the exist attack time is too short and a bigger resistor is required (not 25k but 250k or maybe even more).

 

[Potato Cakes]

That is what I am using. Did to add the 10k resistor to it between the wiper and CCW?

Thanks!

Paul

 

[Greebok]

That is what I am using. Did to add the 10k resistor to it between the wiper and CCW?

Yes, Indeed. But I'm afraid it's still not enough to make transients open.. I heard that people used up to 1mOhm potentiometer..

 

[ilfungo]

Hi
My unit is alive!
2 minor issues...

Meter
3 position:
Input
GR
Output

Correct?

output position
To read 0 on meter the level is Protools full scale .
I need to change something for +4 reading (API METER)?

With output all the way up I have noise at -80 in pro tools.
Essenziale hum.
All the 6.3 are tewisted well....
It's normal?
P.s I'm searching the o-17 shield could be' this make big difference for hum?
Thanks!!!

 

[ilfungo]

Hi
My unit is alive!
2 minor issues...

Meter
3 position:
Input
GR
Output

Correct?

output position
To read 0 on meter the level is Protools full scale .
I need to change something for +4 reading (API METER)?

With output all the way up I have noise at -80 in pro tools.
Essenziale hum.
All the 6.3 are tewisted well....
It's normal?
P.s I'm searching the o-17 shield could be' this make big difference for hum?
Thanks!!!

News I've change the link for + 4  and now the meter move on In and Out readind .
But for correct reading the 47k resistor must be near 3k...
Someone have the same issue?

The last thing is the Test switch,
Is it reversed ? It's a layout error?
Thanks!

 

[Greebok]

News I've change the link for + 4  and now the meter move on In and Out readind .
But for correct reading the 47k resistor must be near 3k...
Someone have the same issue?

Yep, I have the same issue (but had no time to fix it) in my unit.  In GR mode it works well but IN and OUT modes the arrow hardly moves.. Could you clarify please? What "link for + 4"  do you mean?