ilfungo

From schematic
Remove link between R40 and R41
Connect R41 and R42 ( + 4).
Is your test switch work well?
Mine per layout is reversed...


Is your test switch work well?

Yes, it does.

Remove link between R40 and R41
Connect R41 and R42 ( + 4).

Could you post a photo of it please?

Frankly I was thinking that threshold is not deep enough and thus it looks like my 176 is lacking of compression (though the device itself sounds great). The problem is that I haven't a reference unit at my hands and I don't know exactly how should a proper 176 compress. 
« Last Edit: March 17, 2020, 04:03:43 AM by Greebok »

ilfungo


ilfungo



Frankly I was thinking that threshold is not deep enough and thus it looks like my 176 is lacking of compression (though the device itself sounds great). The problem is that I haven't a reference unit at my hands and I don't know exactly how should a proper 176 compress.
[/quote]

Mine have full scale (GR mode) compression.
Could be a bad 6bc8 or some false contact on pcb.
Try to move 6bc8 on the socket and see if the compression change, test all the components connections and trace connectios...
Have you corrected the ratio switch connections as suggest some post before?

Mine have full scale (GR mode) compression.
Mine one too but I expected definitely a deeper compression ..
Could be a bad 6bc8 or some false contact on pcb.
I did it  many times, I have two selected 6bc8's from Christian Whitemore (propadiotubes) and also 2 good tubes (they probably work well too)
Have you corrected the ratio switch connections as suggest some post before?
Do you mean the jumper on the meter board? Yes I did, now IN and OUT modes show proper activity..

BTW have you tried to change input jumpers? (They are in LO mode by default?)

Also some observations: the 2:1 gives some compression, 4:1 less,  8:1 almost nothing and 12:1 sounds like there's no compression at all - it sounds the same as limiting mode when the attack is switched OFF.

And I do NOT hear a difference (on a vocal for example) on ANY position of the ATTACK knob (with a 25k pot with 10k resistor).
 
So I have the following question for all the users who have successfully built and tuned 176: does this unit give the same clean and deep compression as LA2A gives? PLEASE Could anyone share any audio samples with dry and processed signal in all its modes (2, 4, 8, 12) ?
« Last Edit: March 17, 2020, 03:17:32 PM by Greebok »

ilfungo

Hi Greebok
I don't have tried Hi mode... And You?

For now I can't make a saples becouse I can't go to my studio for virus situation...
I hope to be able to do it soon,,,

ilfungo

The unit seems to sound and work great
I'm only Hum problem but I don't know if it's normal...
Attached the noise figure misured some time ago...
The Hum come from the output, input only hiss and It's normal
Thanks!

Potato Cakes

The unit seems to sound and work great
I'm only Hum problem but I don't know if it's normal...
Attached the noise figure misured some time ago...
The Hum come from the output, input only hiss and It's normal
Thanks!

How tight are your heater leads from the power transformer? I wound up adding DC heaters to solve any hum issues.

Thanks!

Paul

Hi Greebok
I don't have tried Hi mode... And You?
Me not.. But I should try.. but I'm not sure if it really helps..
For now I can't make a saples becouse I can't go to my studio for virus situation...
I hope to be able to do it soon,,,
Oh.. That would be nice..  ::)

Thanks!

Paul

Hey Paul, do you have any audio samples recorded through your 176? If it's possible could you share them please?


Potato Cakes

Hey Paul, do you have any audio samples recorded through your 176? If it's possible could you share them please?

https://slinky.to/9to5-TheMusical

All of of the vocals and kick drum were processed through one of my 176's. It's not a good quasi-scientific before and after comparison, but it's the only one I readily have. Also the fact that all of the vocals are recorded through omni directional mics sown in their wigs and being performed on a very live stage should be taken into consideration.

Thanks!

Paul

ilfungo

How tight are your heater leads from the power transformer? I wound up adding DC heaters to solve any hum issues.

Thanks!

Paul

Thanks!

very tight!!!
I want to go with dc heater but now  in Italy is very difficult to receive something...
There is a simple schematic for dc heater?
Thanks!

All of of the vocals and kick drum were processed through one of my 176's. It's not a good quasi-scientific before and after comparison, but it's the only one I readily have.

Thank you Paul!

Maybe you you could show any single track as well please?  ::)

« Last Edit: March 19, 2020, 11:37:30 AM by Greebok »

Is your test switch work well?
Mine per layout is reversed...

OMG... it looks like "test 2" is actually "operate"  :o .. In this mode it works much better as the compressor itself.

PLEASE could anybody confirm that the test switch is actually inverted ???

UPD. Yes, there's another mistake in the layout, so the image of the test switch is inverted.
« Last Edit: March 19, 2020, 12:51:25 PM by Greebok »

Potato Cakes

OMG... it looks like "test 2" is actually "operate"  :o .. In this mode it works much better as the compressor itself.

PLEASE could anybody confirm that the test switch is actually inverted ???

UPD. Yes, there's another mistake in the layout, so the image of the test switch is inverted.

Again, I had wrote about this in my build post earlier in this thread. This is how mine operates.

Thanks!

Paul

core13

If you are using centalab switch.
I think they have both way available
So the drawing is ok for some and wrong for other

ilfungo

Yes for me was inverted...

core13

Does R3 and R4 the 6.8K resistor on the calibration pcb need to connect to both vias?

also for R12 and R14 my resistor drifted so they measure 5,3K instead of 4,7k is it ok?

R18 and r21 same problem, I have 192K instead of 180K.

« Last Edit: March 20, 2020, 02:53:11 PM by core13 »

ilfungo

Update:
The unit is calibrated and sound fantastic!!!
The only problem is the hum .
It's 50hz predominant and depends from output level.
I think it's not heater problem.
Suggestions?
Thanks!

ilfungo

Can someone explain this?
Why in Universal Audio manual GND and B+
are 2 different things?


 

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