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EQ573 Equaliser / Re: 12-position switch has too many legs?... (Three pole switch, one pole on PCB)

« Last post by JPK on September 09, 2024, 08:56:04 AM »

Sorry for the confusion.
You have to cut two pins, but not just any pins.
First make sure the switch is rotated all the way counter clockwise.
Then locate the stops which prevent the switch to rotate continuously (circled in blue in the picture).
The pin you want to keep is the one closest to the stops on the inner circle (circled in green).
Cut the 2 other pins on the inner circle (circled in red).

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MU524 Vari-Mu Tube Compressor / Re: Light Hiss/Noise

« Last post by JPK on September 09, 2024, 08:16:38 AM »

Thank you for the update.
Did you try with a different lunchbox?
We are currently using API, Lindell, IGS lunchboxes without a noise problem.
We also work at strong line levels which helps.

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MU524 Vari-Mu Tube Compressor / Re: Light Hiss/Noise

« Last post by egelmett on September 09, 2024, 04:45:10 AM »

After taking your advice (reflow all film and ceramic capacitors), the odd noise related to the cover is gone. I did this to both units.

I did remove the transformer to examine C12 for any perforation. There were none. As a safety measure, I sanded down the closest transformer pins for clearance, and added electrical tape around C12...just in case.

Still, the EL500 case is too noisy to use the MU524 in it. The transformer picks up hum from the power supply, even when the MU524 is farthest away from the power supply.

And, analog being analog...there is still some inherent noise. On loud sources, not a big deal. For me, this is my opinion, too noisy for delicate sources like voice and acoustic guitar.

I see you have a solid state opto compressor kit! 

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EQ573 Equaliser / 12-position switch has too many legs?... (Three pole switch, one pole on PCB)

« Last post by Tinu_CH on September 07, 2024, 07:16:19 PM »

Hi JPK!

Working on my 573 module at the moment, all is well until now.
Now i'm confused that the 12-way rotary switch for the mid frequency has three central connectors (There's like
an outer and inner ring of connectors), but only one hole for the inner connectors on the PCB.

edit: I think as an electronics idiot - the actual switch is a 12-way three pole switch, but the PCB
is made to accept a 12-way one-pole switch.

Is this a sourcing thing? Can two of the three legs just be nipped off?

Thank you very much for clarification

Best, Martin

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MU524 Vari-Mu Tube Compressor / Re: Light Hiss/Noise

« Last post by egelmett on September 03, 2024, 06:09:19 PM »

JP,

It's been a while since my last post on this. Even when used for Line In/Line Out (i.e. no preamp input), there is audible hiss and I'm not using them.

Along the lines of moving slots, I tried one in an Empircal Labs EL500...and the noise was even worse in either slot. I cannot use them with the EL500 in any way. The MPU566 I built are not noisy in the EL500.

I will go over the capacitors again, as recommended...but this is happening on two MU524s...surely, I can't be that inept at incorrectly soldering two units?

Any ideas?

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CP554 Diode bridge compressor / Re: What is the correct way to stereo link two CP554 units?

« Last post by JPK on September 02, 2024, 06:09:06 PM »

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CP554 Diode bridge compressor / Re: What is the correct way to stereo link two CP554 units?

« Last post by Alex Harmer on August 31, 2024, 11:29:44 PM »

Thank you!
They sound incredible, by the way. Thank you for the amazing kit design.

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MP573 Microphone preamplifier / Re: Short circuit check, brief readings.

« Last post by MATTHEW_KING on August 30, 2024, 08:17:37 PM »

It is just displaying 0 so it is probably just overranging.

Thanks for the quick and detailed response as always. 

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MP573 Microphone preamplifier / Re: Short circuit check, brief readings.

« Last post by JPK on August 28, 2024, 06:33:26 PM »

Is it really dropping to 0, displaying a 0 or is it displaying an out of range sign like an L?
In the second case you are ok.

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MP573 Microphone preamplifier / Short circuit check, brief readings.

« Last post by MATTHEW_KING on August 27, 2024, 08:24:58 PM »

I see a momentary reading of 1800 ohms on the multimeter, but it quickly drops to 0. I am using the correct measurement technique with the black probe in the - pad and the red probe in the + pad. The values vary between 1750 and 1950 ohms, but they only appear briefly before disappearing. When I measure again, the reading shows for a short time before vanishing once more. I'm unsure if this is due to an excessively high measurement, capacitors charging, or something else. My multimeter can measure up to 2000 ohms. It will measure 1700, 1800, 1900, 1950, and 1980 depending on how frequently I recheck the pads, but above that, it does not show any measurement. Might it be out of range?