1

SK25/SK99 Discrete Op-Amp / Re: SK-25 half as loud as it should be

« on: December 06, 2023, 09:42:32 PM »

https://youtube.com/shorts/puYFpGsn6fE?feature=share Shows the current state

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SK25/SK99 Discrete Op-Amp / Re: SK-25 half as loud as it should be

« on: December 06, 2023, 09:38:19 PM »

BY vertical do you mean the PCB with the potentiometers? i feel pretty good about them, because when I swap the DOA everything is good.
I've re-flowed the DOA (many times) and now it's better but still very distorted. It sounds like the speaker is torn.

3

CP5176 FET compressor / Re: No audio passing on my 5176

« on: December 06, 2023, 09:35:10 PM »

Ok that's sorted.
With the exception of the unit with the bad DOA in the other thread, the others are great with one exception wherein the link switch doesn't work. It won't click in.

4

CP5176 FET compressor / Re: No audio passing on my 5176

« on: December 03, 2023, 11:47:17 PM »

Yes, there is compression, just no metering. I am able to see LEDS light up and can calibrate in step 10, with both jumpers installed.

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SK25/SK99 Discrete Op-Amp / Re: SK-25 half as loud as it should be

« on: November 29, 2023, 01:11:49 AM »

Just verified all other parts on the SK25 - they are correct.

6

CP5176 FET compressor / Re: No audio passing on my 5176

« on: November 29, 2023, 12:45:11 AM »

Thank you for your help. I calibrated all modules up to the final step, as i was in my workshop with a poor audio interface. All but one were great, and the one that is bad has a bad DOA (separate forum thread).
I tested the other five today in the studio so I could monitor the low end and distortion settings. Audio on the five were great, but two now have no VU metering with the compressor engaged or not. All units had working vu sections that I calibrated the night before. Have you ever come across this?

7

SK25/SK99 Discrete Op-Amp / Re: SK-25 half as loud as it should be

« on: November 28, 2023, 09:34:12 PM »

Did you check these?
What values do you get for R2, R3?
50 ohms would be correct.
Does the DOA sound OK outside the output level? The DOA gain is set by R19, R20 on the compressor.

I checked as much as I could - it's a bit hard to see the transistors with it built.
50 ohm for R2 and 3 - all others read what is printed on the bands.
It sounds awful - audio drops in and out and its quite distorted.
I don't think it is R19 and 20, but I'll double check - but swapping the DOA fixes it so I assume the fault is there.

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SK25/SK99 Discrete Op-Amp / SK-25 half as loud as it should be

« on: November 28, 2023, 04:41:11 AM »

I have built 6 5176 Comps. 5 are working wonderfully after I embarrassingly figured out the bypass button. One is not and I determined, by swapping the DOA, that the DOA was the problem.
I re flowed ll points (used 40/60 solder). All diodes are pointed the right way. All the resistors measured correctly with exception of R2 and 3, but their bands were correct. Not sure what is wrong but with the other DOAs I was able to get outputs at 14AC and this one only allows ~6 regardless of the setting of P6.

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CP5176 FET compressor / Re: No audio passing on my 5176

« on: November 28, 2023, 02:13:02 AM »

My sincere apologies. I misunderstood how the unit worked. I thought that the green LED indicated that it was bypassed. With the Green LED on I can get more than 13.5V. I am proceeding with calibration.

10

CP5176 FET compressor / Re: No audio passing on my 5176

« on: November 26, 2023, 01:46:03 AM »

Part number: H2RA-20-UA
https://www.digikey.com/en/products/detail/adam-tech/PH2RA-20-UA/9830622?s=N4IgTCBcDaIAoAkwCUCCBaMAGdBVVIAugL5A

Thank you.
I'm stuck on step 7.
I'm using: Abelton Live to play your sin file via a Presonus interface via USB. That goes into a Lindell Audio interface with no other modules in it, and the 5176 is extended out of the Interface. With max Abelton gain and volume from the presonus, I'm only able to register 2.8V AC on my fluke meter.

11

CP5176 FET compressor / Re: No audio passing on my 5176

« on: October 13, 2023, 10:42:15 PM »

Check the solder joints on transformer T1.
Check the solder joints on connectors CN3a and CN3b.
Check if you can measure the input signal between the 2 side pins of pot P1.

Ok, I think I see the issue. I'll need to replace CN3. Is there a part number for the plug (male) connector?

12

CP5176 FET compressor / Re: No audio passing on my 5176

« on: October 13, 2023, 12:29:30 AM »

Check the value of R15, R14, R9 (by color code).
Check the direction of C12, C11, C6.
Try to follow the signal in TP1, TP2, L1 top pin.
The DMM must be set to AC volts. The voltage you read must vary with the position of pot P1.

Thank you. All parts double checked and they are correct. Still no AC voltage between TP1 and 0V.

13

CP5176 FET compressor / Re: No audio passing on my 5176

« on: October 12, 2023, 12:34:16 AM »

In passing audio should i be looking at AC or DC on the test points? I'm assuming DC.

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CP5176 FET compressor / No audio passing on my 5176

« on: October 11, 2023, 11:17:27 PM »

I'm using a CAPI module extender to test this with my 500 series rack. It passes a sine wave in bypass mode, but nothing when engaged. Used leaded solder with no additional flux.
Here are my voltage measurements with pictures.


2. Check the DC voltages:
First check the supply voltages as described in the setup guide. - All check out

Check you get no DC volts at the output of the DOA on L1 top pin. Any DC above a few millivolts here shows that there is an issue with your DOA. .- .23 v DC

Next, without any input signal, connect the voltmeter black probe to the 0V pin and note the DC voltages you get at the points shown on the attached picture. Compare with the expected results (more or less 10%).

A: 12.5V
B: -.588V
C: 13.13V
D: -.02V R11
E: 14.89V
F: -.788V
G: -14.8V




3. Try to follow the signal - no signal from TP1, 2, or L1.

15

LA502 Optical Compressor / Error is setup documentation?

« on: September 07, 2022, 06:17:06 PM »

On https://www.soundskulptor.com/docs/la502-setup-guide-01.pdf
Step one says:  IMPORTANT: It is necessary to turn the seven trimmer potentiometers all the way counter clockwise before start. These trimmers are 20 turns so that's a lot of turns to do

But there are only 3 trimmers.

Is this documentation up to date?