I have experience with the 6AS7 which shows that it sounds best at 100V 100mA. Since I would recommend a PP design for decent output (7-8watts), your power supply transformer is not up to the job. You would need at least 4x100mA or about 1/2 an amp. You need at least 165V of B+ to create a decent driver stage. This means you need a power transformer capable of 130V AC and 1A.
A suitable tranformer;
www.antekinc.com/
I built such an amp which used power toroidals as interstage transformers, I would not recommend that but if you can stretch to a pair of interstage transformers(Lundahl LL1660) this is a very good and simple circuit.
Shoog
A suitable tranformer;
www.antekinc.com/
I built such an amp which used power toroidals as interstage transformers, I would not recommend that but if you can stretch to a pair of interstage transformers(Lundahl LL1660) this is a very good and simple circuit.
Shoog
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Just so you know, this output tube can work well SE despite recommendations to the contrary. I built mine a couple of years ago and it's still doing service as my main amp - it is surprising how well it does.
http://www.diyaudio.com/forums/tubes-valves/167872-my-cellini-triode-amp.html
http://www.diyaudio.com/forums/tubes-valves/167872-my-cellini-triode-amp.html
BinaryMike says he will have a 6AS7 PPP circuit done by the end of the year using cheap 70v line transformers here (4th post).
Parsimon: An Ultra-Cheap DIY Class AB PP Pentode Power Amp - AudioKarma.org Home Audio Stereo Discussion Forums
Here are the transformers on sale $10 USD: 30W Speaker Line Matching Transformer | TR7025-30W (TR702530W) | Distributed By MCM
These transformers calculate to 1000 p-p ohms.
I'm also waiting on more info for the build.
No need to find a "tested" "certified" "approved" or whatever schematic, all you need is study a little and undestand, then you can design your own. It is much more enjoyable this way. My opinion.
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No. The phase splitter ECC85 must have some +70...+85 V at the grid to bias the tube.
Well, I stumbled upon this thread a bit late, but here's the circuit I was working on. Perveant is DC-coupled and solid-state up to the 6AS7 grids. This driver slews cleanly into positive grid territory and yields about 30W output from a pair of 6AS7s. The OPT is a $12 speaker line matching xfmr from MCM (555-7125) with nominal primary Z of 1K. It limits performance below 40~50Hz, as expected, but this amp still leaves a satisfying sonic footprint. Individual 6AS7 triodes generally don't conduct equally at low current levels, but the 22R cathode resistors enforce pretty good current sharing at high levels. I never built Perveant into a chassis, partly because of power supply complexity and partly because I tend to lose interest in many projects past the breadboard stage.
Ignore the IP notice on the schematic. This design is released into the public domain.
Ignore the IP notice on the schematic. This design is released into the public domain.
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