Sony C-800 schematic

Hi all!

As title says I'm looking for Sony C800 schematics. Web is full of C800G schemas but it seems C800 circuit is bit different and thus perhaps different voltages etc.
Problem with the mic is weakened output and highs. Reason might be as easy as old tube.

Anyway if someone has schematics that would be a great help.

Cheers,
Paavo

If you think it's a failing tube, then should be easy enough to swap it and see what happens

Yes that's true. Tube shop just isn't open yet (6:36am)
More seriously, I would like to know voltages specified for this mic. I assume they are more or less same with with 800G but my assuming isn't same than fact.

-Paavo

Sony C-800 non-G schematic

http://www.gyraf.dk/schematics/Sony_C800_Article_03.gif

part of "A Japanese article about the Sony C800 Microphone" at http://www.gyraf.dk/schematics/schematics.html

Sorry, no translation from japanese...

Jakob E.

For some reason I can post, but whenever I tried to paste my answer I get the following error:

The following error or errors occurred while posting this message:
The message body was left empty.

Axel

Here's a screen shot of what I'm trying to post.
It previews well, but always returns the same error when I hit 'post'.
Unfortunately, I'll soon have to leave for the day, so will not be able to solve that mystery before tomorrow.
Axel

Hi guys and thanks for your input. Very helpful!

I saw Jakobs articles last night but totally missed schematics.
This "weeker output and highs" problem is described by our rec engineer who has used mic for ages.
Right now I'm waiting to get mic warm enough to check voltages but when it was cold voltages was pretty much same with C800G. I'll double check them later and meanwhile going to get new tube.

I checked component values and marked them in pdf file attached. I share it in Tech Doc area too.

I don't get what is idea of voltage divider by R106 and R107. Can anyone please enlight me?

Cheers,
Paavo

kilmister said:

I don't get what is idea of voltage divider by R106 and R107. Can anyone please enlight me?

Click to expand...

Floating the heater voltage somewhere around 2/3 of HT voltage. This quietens down some tubes.

Jakob E.

Thanks for explanation Jakob.

Got new Brimar 6AU6 tube. Shop didn't have 6AU6A version. Sound is definitely better now.
Heater voltage is bit low at 5,4V when it was 5,7V with old tube. Also plate voltage is little low in my opinion as it's around 210V with both tubes. Bias voltage is 1,3V. I assume also PSUs tubes have worn so I'm getting some russian substitutes to test in psu.

Cheers,
Paavo

I think the tube used in C800 + G are not a "real", but a Russian "equivalent" of the 6AU6 - this can be deducted from it's slightly different size, shape and internals. The russian version tends (on average) to give much lower noise in this mic.

Jakob E.

I can tell you after trying many different tubes in the C-800G that the ONLY tube that sounds right is the Sony supplied correct replacement part. I imagine this is similar in the C-800.
Of course other tubes work, but considerably change the sound of the mic, and what they change is the thing most folks like about the mic (top end / presence).
As far as noise, I have had to sort the ones from Sony, I'm not sure if they noise grade them...
Kind of a drag, as I'm sure Sony will stop selling them as they are prone to do with all parts, but at least they are not crazy expensive.
You can use the other tubes you bought in the power supply!

Thanks for info.
I ordered those 6J4P tubes for power supply but regarding Jakobs post I'll definitely give them a try in the mic also. I really should diy isolation chamber to measure noise floors myself...
The old tube was Tungsram EF94. Current owner of the mic has purchased mic as a second hand so it's possible tube has been changed at some point before. I haven't open psu yet so I don't know what brand of tubes it has inside.

I got email today from finnish company who are servicing Sony stuff. Guy was very helpful and found service manual (probably) for the psu and I should have it in paper at least but there's slight change for pdf file. Manual should tell correct plate voltage. I'll share manual whenever I get it.

Cheers,
Paavo

Did you have any luck with the power supply manual in the end? If you could share the PDF it would be amazing!

You are replying to a 12 years old thread.

That japanese article can now be translated with google-translate in camera mode

/Jakob E.