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MP566 Tube microphone preamplifier / Re: Stops working after some time after years in use

« on: September 02, 2023, 01:20:25 PM »

Thank you!

I guess that fixed my problem.
Both the DC converter and the two PTCs had to be replaced and the upgrade from 200mA to 300mA finally fixed it!
Thanks for your fast and continuous support!

Tested the preamp for 2 ½ hours and had yesterday a gig and no problem at all!

Really love your modules!

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MP566 Tube microphone preamplifier / Re: Stops working after some time after years in use

« on: August 28, 2023, 11:40:06 PM »

Sorry to bother you again.

I used it this weekend at a festival and I worked like a charm. about 45 min prior to the gig and the 1 hour and one of the main vocals was using the MP566 in the insert. So far so good 😉
After the hour the gave an encore and just in that moment the main vocalist was gone on the PA and no input signal on the MP566.

So two questions:
- I know, don't let it get too hot. BUT it worked in that API 500 casing for the last 8 years! and in the rack I have one rack unit with a mesh for ventilation above the API rack.
- second: I didn't change the resettable fused yet. As you mentioned, I want to try that next.

While removing the PTCs from the board I noticed that the ones used in my revision of the board are 200mA and in the newer documentation 300mA resettable fuses are used 😳 
Could this be a cause for the problem as well (obviously the high voltage converter was worn out too over the years as it worked way longer than with the old device installed)?

Is it save or even a good idea to use 300 mA PTC instead of 200 mA for revision 1.3? (last modified 07/07/2015)

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MP566 Tube microphone preamplifier / Re: Stops working after some time after years in use

« on: August 25, 2023, 10:41:24 PM »

Ok, now I got the replacement part for the high voltage converter and replaced it. After continuous run for over an hour I guess it's considered a fix. 😉 

Bought it almost exactly 8 years ago, just one broken part is a good outcome!
I really like the Sound Sculptor kits for it's quality and sound 😉 
and the good help on this forum

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MP566 Tube microphone preamplifier / Re: Stops working after some time after years in use

« on: August 22, 2023, 01:01:58 AM »

Thanks for your help!
Had no time over the weekend to work on this and now I got my replacement tube. As you guessed, it didn't fix the problem. After about half an hour the problem returned - then after turning off the lunchbox for about 5 minutes got it working again and it started like the sound was faded in.
So maybe your guess with the high voltage regulator is correct.
I will investigate that further and will order the replacement parts anyway as it's a good idea to have spare parts around 😉 

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MP566 Tube microphone preamplifier / Stops working after some time after years in use

« on: August 15, 2023, 10:40:26 PM »

Hi all,

maybe someone can give me a hints what's wrong with my MP566:

I built it some years ago, since then using it for live sound for my main vocal channel as the first stage followed by an EQ573 and CP5176.
Working like a charm and never let me down!

Three days ago it suddenly stopped working. Input led went dark and no switch changing or on off of the lunchbox fixed the problem. I removed it from the lunchbox as it was in bright sunlight and got a bit hot but not tooo hot! After some hours I reinstalled it and it worked. Day after that it worked and today I'm testing things at home and after initially working it suddenly stopped.

I changed the tube to an older one and it seemed to be the fix at first but after about half an hour it again stopped working.
Then I noticed that it emitted a strange sound like a square wave or low frequency digital noise (just lows and mids, no highs as a sound description).

Swapped the tubes again and now it's working for the moment.

My question now is:
is this a sign of a dying tube or is there something else broken? No obvious signs visible like blown up parts or goo or nasty stuff ...

Any help greatly appreciated 😉 

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First Aid / Re: Very strange problem with Rupert Neve Design R6, CP5176 and LA502

« on: September 06, 2021, 09:19:01 AM »

thank you for this hint!

As I did not change the cabling from the patchbay to the 500 rack and while testing I used different slots and cables I have to check the inner guts of the rack for bad contacts or solder joints ...

But now I have idea where to look, thanks!

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First Aid / Very strange problem with Rupert Neve Design R6, CP5176 and LA502

« on: September 04, 2021, 03:46:10 PM »

Hi,

I have a very strange problem.
My setup is a R6 Rack with MP5.66, EQ573, CP5176, MP573, mEQ, LA502.
Today when routing a bass track through the LA502 I did get a very very quiet signal, if I put the output to max its distorted and there is complete lack of bass and more high frequencies than the original.
I checked with the CP5176, the signal is quiet but only a bit but there is complete lack of bass.
I checked through the EQ573 and it sounds plausible.
If I route through CP5176 and bypass the sound is normal!

Now the very strange thing:
I have a second Rack Fredenstein Bento 6S.
If I put the CP5176 into that rack it sounds and behaves as expected and normal!!!

I checked the +/-16 V and +48V of the Neve Rack and it has correct values. I removed all other modules, changed slots, measured with bypass and without, power seems ok.
I normally use SUB-D connectors of the Rack but triple checked to use XLR ...


Anyone any idea what could cause this strange behaviour??
A power supply should not affect the audio signal ...

any help appreciated
Wolfgang

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CP4500 Stereo Bus Compressor / Ratio flipped?

« on: July 03, 2021, 12:47:22 AM »

Hi,

it's my 6th build of a Sound Skulptor API 500 Module (MP5.66, EQ573, CP5176, MP573 and LA502) 

Everything is working so far and calibration has been done.

One odd thing though: maybe it's too late and/or I'm stupid:
I feed a music signal (Stereo) and adjust the Threshold that the gain reduction meter barely moves.
Important: Ration is on 10!
When I reduce the ratio to 4 and 2 I expected that the gain reduction does NOT increase - but it does!
on Ratio 2 the reduction is the highest.

Am I completely mistaken or am I right that it should be the other way round?

Did I solder the wrong resistors to the rotary switch? double checked it but maybe still ...

Any ideas what could be wrong?

the rest of functionality is as expected.

help greatly appreciated 😉 

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MP566 Tube microphone preamplifier / Bugfinding - low level then normal operation

« on: May 29, 2021, 01:03:22 PM »

Hi all,

I have a strange problem with my MP 5.66 (built some years ago, been on the road and studio):

Sometimes (mostly when I connect it to my X32 as an insert) I either get a very quiet but extremely distorted signal or only a quiet signal and when I crank the gain of my X32 which essentially delivers a high level input to the MP 5.66 and then lower the gain back to a normal level it works without problems the rest of the show(s). It like cleaning the pipes with a high input level ...

Any ideas what the problem could be?

I ruled out my 500 Rack (Neve R6), I changed the tube, I changed cables, channels and used it both as an insert an connecting a mic directly - nothing solved the problem it still occurs infrequently ...

Any directions on how to solve this is highly appreciated 😉