Kondo KSL-M77 phono preamp clone project

[6A3sUMMER]

rzaglinskij,

Thanks for asking!
None of my amplifiers use PCBs.

The KT77 amplifier I built was on a chassis that I use to try out various amplifier circuits.
I built many stereo SE on that chassis with various DHT, and a pentode.

Now I only build mono-block push pull amps on that chassis.
pentode and beam power. I have used in beam power mode, Ultra Linear mode, and Triode Wired mode.

And my latest amplifier circuit is on another chassis, it is a balanced/differential push pull mono-block.
My only differential signal source is a Marantz CD player with XLR outputs.

 

[DerekRonin]

I have been sitting on this unit for quite a while, still undecided about whether to recap or repurpose. It was pulled out of an old RCA model 400 projector. Hopefully, to finally get it out of the junk drawer and into something operational, something to pair with the M-77.

 

[Boydk]

Could you please start a new thread about PA/KT77 or whatever??
Following this thread and getting notifications about new post, that have nothing
to do with KSL-M77 is pretty annoying, Thank you.

 

[peppennino]

Hi all,
Could you please share measured anodic tensions on 12AY7 tubes for this project?
Thanks in advance,
Vinz

 

[6A3sUMMER]

peppennino,

345 Posts.
Unfortunately, there is more than one project.
This is a mixed thread.

Line and Phono preamp
movie projector amplifier
Power amplifer

Which project?

Please list the particular project and Post number.

 

[peppennino]

KSL 77, thanks

 

[peppennino]

Nobody? I have a spare transformer and I need anodic tensions...

 

[hesener]

I'm sorry, my preamp is currently on the side. The voltages are printed on the PCB and mine was +/-15V close, if I remember correctly.
I'll try and measure later today...

 

[hesener]

So, in my case the supply voltages are 192V ... 197V, and the Anode voltage of,the phono stage is 144V, the anode voltages of the following stages are 112V. Hope that helps!

 

[peppennino]

Manu thanks!

 

[DerekRonin]

This was what I measured previously, luckily I had it saved for future reference. Hopefully, this helps.

 

[peppennino]

Thanks!!

 

[Erman]

Hi all, I finished my pre too.

I made the measurements at the 12.6v test point on the board and it gives me 11v.

I tried to adjust with the trimmer but nothing happens.

 

[Erman]

Here are some photos

 

[Erman]

Hi, I have shorted all the inputs except the input, can anyone explain?

Thank you

 

[Erman]

I shorted the RCA inputs except LP, can someone explain please?

Thank you

 

[DerekRonin]

Hi Erman, didn't quite understand your question. Are you having phono input problem?

 

[Erman]

Hi Derek, I checked the RCA inputs with the tester, it gives me continuity on the connectors except phono, why?

Thanks

 

[hesener]

from your picture, it doesnt seem the grounds are connected.... some of them are but some do not look like. Only "AUX 2" seems to be connected correctly. Please confirm you have mounted the RCA sockets isolated from the back panel, with the plastic washers.
All RCA grounds need to be connected, ideally from the socket to the PCB signal ground with a good connection. Otherwise the input signal cannot flow...
So the other sockets should all measure "open".

 

[hesener]

OK, checked another picture, seems you have connected with a wire at socket level. I would still recommend for the LP sockets to connect the ground directly to the PCB, since the current setup is creating a big ground loop, with possible crosscoupling of signals from the other sources.
Still not clear what is causing your measurement results. Did you insert the relays correctly?