1

EQ573 Equaliser / R50 wrong resistor value/colour coding

« Last post by G.Matheson on December 10, 2025, 06:22:01 PM »

The measured value and colour coding of R50 (3M3 Ohm / ORG-ORG-BLK-YEL-BRN) does not match the one in the parts list (3M9 Ohm / ORG-WHI-BLK-YEL-BRN). Should I not use the resistor and get the correct one? Or is the error in the spreadsheet?

Thank you
Giulio

2

MP599 Microphone preamplifier / Several issues building the MP466-2

« Last post by Remy on December 09, 2025, 12:45:20 PM »

Dear JPK,

While building the MP466-2, I encountered several issues:

1. The parts list indicates that two 270r resistors should be placed at positions R3 and R5. However, the layout also shows a 270r resistor at R24.
-->Could you clarify the correct resistor values for positions R3, R5, and R24?

2. The parts list indicates that two 6.8k resistors should be placed at positions R1 and R2. However, the layout also shows a 6.8k resistor at R41.
-->Could you clarify the correct resistor values for positions R1, R2, and R41?

3. A resistor with a value of 15k was supplied for position R40. However, the layout shows that a 10k resistor should be placed there.
--> Could you clarify the correct value for position R40?

4. The parts list indicates that a 1k resistor should be placed at positions R4 and R6 and R39. However, the layout shows a 1.2k resistor at R4, R5 and R39
--> Could you clarify the correct resistor values for positions R4, R6, and R39?

5. A resistor with a value of 560r was supplied for position R24. But as mentioned above, the layout shows that a 270r resistor should be placed there.
--> Same question as above: what is the correct value for R24?

3

CP5176 FET compressor / Re: CP5176 only compresses in 20:1 / SLAM mode

« Last post by JPK on December 05, 2025, 11:44:30 AM »

The problem lies around U1-U2, R33, R34, R35 and maybe R28 to R32.
The signal gain between U1-pin5 and TP3 should go from 1 to 9, depending on the ratio switch.
Your gain goes from 6 to 21. The gain is based on these resistors.

4

CP5176 FET compressor / Re: CP5176 only compresses in 20:1 / SLAM mode

« Last post by Ptb on December 04, 2025, 03:56:20 PM »

Measurements: U1 pin 1 = 1.10 VAC, U1 pin 5 = 0.55 VAC.

I inspected the solder joints around U1 and the checked resistors; solder joints look OK and the resistor values (R25, R27, R33, R34, R35) match the values.

5

CP5176 FET compressor / Re: CP5176 only compresses in 20:1 / SLAM mode

« Last post by JPK on December 01, 2025, 04:04:12 PM »

With the same conditions as in 4. Check the side chain
What AC voltage do you get on U1 pin1 (1.4VAC) and U1 pin5 (0.7VAC) ?

Check the solder joints and value of resistors R25, R27, R33, R34, R35.

6

SK49 Multi-patern Tube Microphone / Re: How long is the 7-pin XLR cable that comes with the SK49 kit?

« Last post by JPK on November 27, 2025, 11:34:32 AM »

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EQ573 Equaliser / Re: Signal going through the unit but it doesn’t effect the sound

« Last post by JPK on November 27, 2025, 11:34:15 AM »

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CP5176 FET compressor / Re: CP5176 only compresses in 20:1 / SLAM mode

« Last post by Ptb on November 26, 2025, 09:29:48 PM »

Thanks, here are the measurements

AC level on TP3:

• Ratio 2 : 0.65 VAC = 3,3
• Ratio 4 : 1.3 VAC = 6,58
• Ratio 8 : 2.1 VAC =  9,04
• Ratio 12 : 3.4 VAC = 11,02
• Ratio 20 : 5.9  VAC = 11,69
• Ratio SLAM : 6.6 VAC = 9,56

DC level on TP4:

• Ratio 2 : 0 VDC = 0
• Ratio 4 : -0.5 VDC = -0,5
• Ratio 8 : -1.3 VDC = -1,3
• Ratio 12 : -2.5 VDC = -2,5
• Ratio 20 : -5.5 VDC = -5,5
• Ratio SLAM : -0.6 VDC = -0,6

DC level on JMP1 pin 1:

• Ratio 2 : 0.6 VDC = 0,7
• Ratio 4 : 0.9 VDC = 14,42
• Ratio 8 : 1.2 VDC = 12,3
• Ratio 12 : 1.9 VDC = 11,78
• Ratio 20 : 2.3 VDC = 9,17
• Ratio SLAM : 7.9 VDC = 13,8

DC level on TP6:
      -4.5 to -1.2 VDC depending on P6 = -13,2

DC level on TP5 with jumpers JMP1 on 2-3 and 4-5 [o o-o o-o]:
      0.32 VDC =  0,32 

A 12,7
B -0,6
C 13,3
D -0,2
E 15
F -0,8
G -15,1

9

EQ573 Equaliser / Re: Signal going through the unit but it doesn’t effect the sound

« Last post by Colindsv on November 25, 2025, 10:57:48 PM »

Fixing the relay worked!


Thanks for your help!

10

SK49 Multi-patern Tube Microphone / Re: How long is the 7-pin XLR cable that comes with the SK49 kit?

« Last post by Alex Harmer on November 25, 2025, 10:57:37 PM »

Thanks very much for an amazing microphone design!

I've just finished building my pair in New Zealand. They are working perfectly, no issues.