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MP566-II Tube microphone preamplifier with HPF / Re: Several issues building the MP466-2

« Last post by Remy on December 12, 2025, 06:32:13 PM »

Dear JPK,

Thank you for your reply and for the corrections on the layout. Hopefully, the mic preamp will work once I’ve finished building it.
I have another question: would it be possible for you to send the XT500 as a concession? This would allow me to properly test the preamp.

(I’m asking here on the forum because when I try to email, I receive a “non-deliverable” message with the following error.)

The recipient server did not accept our requests to connect.

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EQ573 Equaliser / Re: R50 wrong resistor value/colour coding

« Last post by G.Matheson on December 12, 2025, 02:41:22 PM »

Ok thank you, I've sent an email confirming my address.

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EQ573 Equaliser / Re: R50 wrong resistor value/colour coding

« Last post by JPK on December 11, 2025, 06:15:21 PM »

This is an error in the kit. Sorry for the inconvenience.
Please contact us to confirm your address and we will send you the correct resistor of 3M9.

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MP599 Microphone preamplifier / MOVED: Several issues building the MP466-2

« Last post by JPK on December 11, 2025, 06:13:17 PM »

This topic has been moved to MP566-II Tube microphone preamplifier with HPF.

https://www.soundskulptor.com/forum/index.php?topic=7381.0

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MP566-II Tube microphone preamplifier with HPF / Re: Several issues building the MP466-2

« Last post by JPK on December 11, 2025, 06:09:14 PM »

Thank you for reporting these errors in the layout PDF.
The schematic and parts list are correct.
I have attached the correct layout file.

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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

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MP566-II Tube microphone preamplifier with HPF / 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?

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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.

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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.

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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.