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MP573 Microphone preamplifier / Inline-attenuator after MP573 and before interface

« Last post by morast on March 13, 2026, 02:30:03 PM »

Hi,

i just finished building my first of 2 MP573 - everything worked fine & sounds great. However, i only afterwards noticed, that the grey output level knob is placed before the output transformer (which is explained in a blogpost on soundskulptor website) and i can not fully drive the output stage and attenuate signal after (like i think it's possible on my MP512s) without overloading my RME line-ins.

Due to lack of space in my lunchbox i cannot use a PAD500 module - is it possible to just plug in a switchable inline attenuator like the Shure A15AS or the AT8082 which have around 1kOhm impedance according to specs, to get a similar attenuation without change in sound?

(My RME line-ins that come afterwards have 10kOhm input-impedance).

Thanks for you infos & cheers from Austria,
Herbert

2

TS500 Tape Simulator / Re: “bump” problem

« Last post by JPK on March 05, 2026, 04:57:16 PM »

I noticed a bump when I switch to 30ips from 15ips, and from 7.5 to 15ips.
Do you also get these pops when there is no input signal?
You can compare to the other unit when it is finished.

I have one 100pF to insert in c65.
Sorry for the mistake. Yes, a 100pF will be OK.

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CP554 Diode bridge compressor / Re: V+ and V- voltage

« Last post by JPK on March 05, 2026, 04:40:02 PM »

Not an issue. The Wes is just a little above the standard voltage.

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TS500 Tape Simulator / “bump” problem

« Last post by gobert4 on March 05, 2026, 03:58:56 PM »

Hi,
I assembled my first TS500 and I noticed a bump when I switch to 30ips from 15ips, and from 7.5 to 15ips.
From 15ips to the other velocity the bump is low.
Is normal?

Second question:
I received the second unit yesterday and I have x2 47pF ceramic instead of x3.
I have one 100pF to insert in c65.
Can it be ok?

5

CP5176 FET compressor / Re: My CP 5176 is very quiet on the input stage

« Last post by JPK on March 05, 2026, 03:55:57 PM »

Try removing Q1 on the broken unit. If the sound is back then Q1 is the culprit.

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CP554 Diode bridge compressor / V+ and V- voltage

« Last post by vwyf11 on March 05, 2026, 03:39:16 AM »

Hey,

I’m just getting to testing the compressor and I’m getting readings from V+ to V0 and V- to V0.  It says I should be getting readings between 15-16V negative and positive, but I’m getting readings around 16.7V.  Just wondering if this is going to be an issue.  I’m using a Wes audio titan for testing.

Thanks

7

CP5176 FET compressor / My CP 5176 is very quiet on the input stage

« Last post by Denis on March 03, 2026, 06:25:40 PM »

Hi guys

one of my 2 5176 is very quiet. it is right behind my 573 and if i crank the gain up around +20db in comparison to my working 5176 it sounds as the other.
I think either Q1 or Q2 is having an issue but Id like to hear from someone who knows what is going on When I use line level 100mVAC to calibrate even at max input and max output it almost does not compress where the working one compresses.

Here my measurements:
DC: everything is fine. the "broken" unit and the working one are the same. Resister values are fine. Specifically all around Q1 are fine. C3 C4 and C7 seemed to be fine. I measured C7 and both fine. I could not measure C3 and C4 but resistance is the same on both units.
AC:here are some differences.

When I the same signal on both units, lets say the calibration 100mVAC I have at tp1 around 60mVAC on both. I have good signal on tp2, I think it was .5mVAC or something but on the broken one it was way less. something around 10mVAC+-.
I checked around Q1 and I have looking at the round side from left to right measured to 0V 60mVAC, 30mVAC and 45mVAC. on the broken one it is 0.0mVAC  0.0mVAC and 25mVAC.



It was working at some point. I dont know what happend. No damage is noticeable. Anything else I can measure to find the broken part?

I would just replace Q1 but I found that the BF245 has different pin outs? I found 2 different variants called the same. Or is it maybe some different part?

EDIT:
On the working unit I have with 60mVAC on tp1 and output at 100% I have 1.1VAC on tp2, on the broken unit I have 14mVAC on tp2

Thanks a lot!
Denis

8

EQ573 Equaliser / Re: EQ573-II doesn't play sound

« Last post by JPK on February 22, 2026, 10:09:45 AM »

Check if you get the signal on U1 pin 5.
- If not, the issue is around the high pass filter. Check the solder joints on rotary switch SW1, connectors J5a-b and J6a-b.
- If true, the issue is in the relay RLY1 or in U2. Check the solder joints. Try replacing.

9

EQ573 Equaliser / Re: EQ573-II doesn't play sound

« Last post by andrixb on February 21, 2026, 01:43:23 PM »

Checked. On TP3 is 0.9VAC and TP4 0.8VAC

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EQ573 Equaliser / Re: EQ573-II doesn't play sound

« Last post by JPK on February 20, 2026, 11:36:28 AM »

Also check TP3 and TP4 (the audio goes through them before TP2).