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MU524 Vari-Mu Tube Compressor / Re: manque JmP1 et ref transistor

« on: Today at 09:56:12 AM »

En effet, le document n'est pas  à jour, nous corrigeons immédiatement !

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MU524 Vari-Mu Tube Compressor / Re: manque JmP1 et ref transistor

« on: May 11, 2025, 03:43:10 PM »

Embase 2 broches : Désolé c'est une erreur, on vous envoie ça demain.
Les transistors sont identiques, pase de problème.
Le pot 202 et le bon. Sur quel document avez-vous vu 203 ?

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MU524 Vari-Mu Tube Compressor / Re: MU 524 Stuck on Step 7

« on: May 06, 2025, 04:36:25 PM »

TP3 = TP4 = 0 VAC
Were you able to get 9VAC in step 6?
If true, then you may have a defective tube. Contact me here for a replacement.

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MP573 Microphone preamplifier / Re: Laster Version of the Assembly Docs, Docs-24

« on: May 05, 2025, 09:30:44 AM »

DOCS-20 is the correct documentation. The changes between DOCS-20 and DOCS-24 affect other products.

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MU524 Vari-Mu Tube Compressor / Re: MU 524 Stuck on Step 7

« on: May 05, 2025, 09:28:13 AM »

Check the solder joints on R6, R7, R9, R10, Q1, Q2.
Check that TR2 is working properly: Resistance going from 0 to 1k between center pin and one side pin and goinf from 1k to 0 on the other side pin.
Check again the balance setting after removing U4.

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XT500 Lunchbox connector extender / Re: Ribbon Cable Direction

« on: April 28, 2025, 08:27:25 AM »

Granted, I can flip the ribbon cable, but then the ribbon will be kind of going over the test pins.
This is what we do. The cable is correct, we purchase it pre-assembled. Going over the test pins is not a big problem.

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True-Grit Tube saturator / Re: True grit / Relais RLY1

« on: April 27, 2025, 09:59:26 AM »

Oui, exact.

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True-Grit Tube saturator / Re: True grit / Relais RLY1

« on: April 26, 2025, 05:08:07 PM »

C'est le bon relais, vous pouvez souder !

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MU524 Vari-Mu Tube Compressor / Re: Tube ECC189 de remplacement

« on: April 24, 2025, 07:17:34 PM »

Ils n'indiquent pas la marque mais vous pouvez essayer.
Les réglages doivent permettre de s'adapter à la plupart des marques.

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MU524 Vari-Mu Tube Compressor / Re: TR4 will only go down to 5V

« on: April 24, 2025, 07:13:37 PM »

You are on step 8, right?
What is the DC voltage on TP6 whenTR4 is all the way CCW.
Same question on U1 pin1 ?
Same question on U4 pin6 ?

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MU524 Vari-Mu Tube Compressor / Re: something wrong with my build

« on: April 24, 2025, 07:05:50 PM »

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MU524 Vari-Mu Tube Compressor / Re: No AC volage from TP1 on

« on: April 11, 2025, 09:54:00 AM »

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MU524 Vari-Mu Tube Compressor / Re: No AC volage from TP1 on

« on: April 07, 2025, 05:41:23 PM »

Did you check the glowing in the dark? Because it is not very visible in daylight.

Power up the lunchbox: 5,5 V then more to 6.2 V after 10 seconds.
Do you confirm this? Check the solder joints of the tube socket and the header connecting the tube PCB to the main PCB.

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MU524 Vari-Mu Tube Compressor / Re: No AC volage from TP1 on

« on: April 04, 2025, 10:05:48 AM »

Check value, dirction and solder joints of L1, L2, C30...C33, R38, R39, D9, U6, Q4.
In particular, make sure U6 and Q4 are in the correct direction:
- Pin 1 of U6 towards L2, coil facing T1.
- Writings on Q4 towards R39.

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MP512 Microphone preamplifier / Re: LED activity reflected in sound

« on: April 02, 2025, 03:18:19 PM »

Can you try to reproduce the effect with pulses of sine wave coming from a generator pluggin?
This is because I don't understand how it could be caused by the preamp.

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MU524 Vari-Mu Tube Compressor / Re: Tube PCBs

« on: April 01, 2025, 04:10:56 PM »

The tube PCB's are the same except for the test pins added on the True Grit.
The tube socket is this one:
https://www.tubeampdoctor.com/en/9-pin/noval-socket-ceramic-white?c=58

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CP4500 Stereo Bus Compressor / Re: CP4500 - No output and incorrect voltages

« on: April 01, 2025, 04:02:35 PM »

Do you confirm that TP11 is at 0VDC ?
If true there is something wrong arount U21 and R95 to R99. Check the resistors value.

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MU524 Vari-Mu Tube Compressor / Re: No AC volage from TP1 on

« on: April 01, 2025, 11:03:00 AM »

Dead tube. Contact us here for a replacement.

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MU524 Vari-Mu Tube Compressor / Re: No AC volage from TP1 on

« on: March 31, 2025, 07:43:52 PM »

Measure the resistance of the tube heater between pins 4 & 5 (tube removed). You should get around 3-4 ohms.

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MU524 Vari-Mu Tube Compressor / Re: something wrong with my build

« on: March 31, 2025, 07:37:43 PM »

Is RLY1 in the correct direction?
Can you measure the signal on U2 pin4? With and without U2 inserted.
Is U2 correctly powered on pins 5(-16V) and 6(+16V)?
Try removing BR1.

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CP4500 Stereo Bus Compressor / Re: CP4500 - No output and incorrect voltages

« on: March 31, 2025, 07:28:54 PM »

Check if the voltage on R95 left pin moves with the Threshold pot. Should go from -12V to +12V

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MP512 Microphone preamplifier / Re: LED activity reflected in sound

« on: March 31, 2025, 07:25:05 PM »

A sound clip could help me understanding.

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EQ573 Equaliser / Re: 573 there's no audio signal when I select XLR.

« on: March 31, 2025, 07:23:53 PM »

Please report the DC voltages shawn in this post, against TP4.
https://www.soundskulptor.com/forum/index.php?topic=25.msg41#msg41

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MU524 Vari-Mu Tube Compressor / Re: something wrong with my build

« on: March 28, 2025, 05:47:01 PM »

Do you measure 15VDC against 0V on both pin1 and pin8 ?

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MU524 Vari-Mu Tube Compressor / Re: No AC volage from TP1 on

« on: March 28, 2025, 05:41:50 PM »

Is the tube heating? Does it glow in the dark?
If not, check value, direction and solder joints of L1, L2, U6, C30 to C33, D9, R38, R39, Q4.