ECL82 (6BM8) PP Stereo

[Family_Dog]

The "about 270K" resistor should be trimmed so the first plate sits at 1/4 to 1/3rd of the supply for that stage (so the cathodyne is well biased). The output stage cathode resistor is about 200 ohms, and may work better with a bypass resistor. I've set NFB with 2K7 and 27K fairly arbitrarily, change the 27K to taste.

An externally hosted image should be here but it was not working when we last tested it.

This project has come alive again. I have existing output transformers which I want to use with this design. The transformers have a primary value of 6k6 with UL taps set at 20%. I gather I can use this circuit in an UL O/P configuration with no difference in design other than
perhaps playing around with the 200e output cathode resistor and monitoring the HT voltage into the input stage after wiring it in UL mode?

-Eric

 

[triode_al]

I just finished my Revox Modell 40 remake, in principle like streetdogs schema, apart from tha fact that the firts stage and the second are decoupled; and I made it int a triaode out (screen traditional 100 ohms to anode); 300 Va and Vg=-12V with CCS at 30 Ma total.
It is very good on my QUAD Esl's. Very very good, warm and hearty.
Try triode maybe before going UL?
The ESL is hard to drive; this is really done with good success in triode connection.
albert

 

[planet10]

with UL taps set at 20%.

Maximum power taps

dave

 

[avincenty]

Surplus PCL82 PP Stereo

I finished building a PCL82 Push Pull stereo amp using the schematic from post 713745. The only difference is that I had to change the cathode resistors as the one on the schematic was exceeding the plate dissipation of the tube. I ended up putting a 1K ohm resistor, drawing an quiescent current of 25ma. Since the tubes were surplus and unmatched, one of the tubes had a combination of a 560ohm and a 1K 15 turn trimmer from Radioshack. This way I was able to match the currents. Other than that the amp is very silent and sounds very nice. Need to build some high sensitivity speakers next.

The amp is build will almost all surplus parts.

output transformers are 7010 line matching transformers, 8K to 8 ohms.
Power transformer is a triad 35va isolation transformer with a voltage double power supply.
The heater is a 16v @ 1.6amps.
The case is a LACIE usb drive case.

Link to schematic
http://www.diyaudio.com/forums/showthread.php?postid=713745#post713745

Link to pictures (first time trying picasa links)
http://picasaweb.google.com/lh/phot...authkey=Gv1sRgCJ361dDv9q6j-wE&feat=directlink
http://picasaweb.google.com/lh/phot...authkey=Gv1sRgCJ361dDv9q6j-wE&feat=directlink
http://picasaweb.google.com/lh/phot...authkey=Gv1sRgCJ361dDv9q6j-wE&feat=directlink
http://picasaweb.google.com/lh/phot...authkey=Gv1sRgCJ361dDv9q6j-wE&feat=directlink
http://picasaweb.google.com/lh/phot...authkey=Gv1sRgCJ361dDv9q6j-wE&feat=directlink

 

[planet10]

I've not run across that LaCie case before -- usually if they are that big they have triple interface.

I like it.

dave

 

[avincenty]

Yes you are right, it was a 2TB multi port. 3 Firewire, 1 USB.

Alfredo

 

[jamesdb]

ECL82 PP Kit

You can try this kit:
http://audio.engineeringvista.com/AudioKits/Model-1/index.htm

 

[planet10]

Re: ECL82 PP Kit

You can try this kit:
audio.engineeringvista.com/

That kit is single ended not PP. Nice thou.

dave