Looking for Mic Tech [Los Angeles] C-800G

I'm hoping someone might be able to point me in the direction of a good tech to service/mod my immaculate C-800G

Its lost a lot of life recently. I've changed the tube a few times but think the mic and power supply need a little more attention.

The noise floor has increased and there is a buzz that appears after a while but dies instantly after powering down the PS, leading me to believe the caps need replacing.

also, anyone know the best tubes (russian/telefunken etc.. 6au6a/ef94/6j4p) and where they can be sourced? ebay is hit or miss.

Thanks a lot

Regards,

Jess

Hello,
In " The Lab " Meta-Meta :
Sony C800G tube mic schematic, DIY and discussion, C800 clone :  http://www.groupdiy.com/index.php?topic=256
Best,
Guy

I PM'ed you.
Best,

Guy

The last time mine went south I sent it to Sony and it came back great!
If you have been swapping tubes then you have been mucking in there with the gooey copper tape and all that heat sink baloney.  Life is too short for important sessions.
Really, if you have the time and want to build one, well, kinda one that is awesome for a DIY, there is mucho info here.  If you have four figure sessions in the near future, send it to Sony.  They fix it to spec and ship it back with a guarantee.
Unless you have the time and an anechoic chamber n' stuff. . .
Mike

There was a schematic of the PS on the web, if I find the link I will post it.  IIRC it was drawn using two 6au6s as diodes in the power supply for the B+. 

Finding low noise 6au6s can be a issue.  I ended up using the Russian made 6au6 like one with the longer glass body. 

Gus said:
"There was a schematic of the PS on the web, if I find the link I will post it."

No need to search that far. It's right here in the Lab!
http://www.groupdiy.com/index.php?topic=23666.0

This one was my first contrib here. I will post the link in the microphone meta to make it easier to find...

Axel

If you look at the Sony microphone section schematic you will note the plate current is 1.4 ma.  If you study other tube microphones and schematics you might want to take note of the plate currents.
http://www.groupdiy.com/index.php?topic=9

I built something like a c800g circuit to check the operating points of the 6au6 with that Sony circuit.  I did not use the cooler or the same transformer or the same capsule so it is not a clone but its own thing with the 6au6 circuit I wanted to test the use of the 6au6 as used in the C800G.  I have learned a bit more since that older thread so question what I posted in it.

I don't think your Caps need replacing, best bet is to find some nos rca's that fit. the buzz could be the tube its self or you could have an intermittant connection in the cable or connectors.

JessJackson

  Did you check the tubes in the power supply?