Compact ~20WPC Tube Amp

@charles1dad   The best amp I've ever heard uses 6sn7 to drive 6c33c.  I just picked up an amp to play with, partly because it uses 6sn7 to drive many choices of power tubes.  I'm eager to experiment with it.

@carlsbad 

The best amp I've ever heard uses 6sn7 to drive 6c33c.  

I believe you. The 6SN7 is a renowned tube. As with anything the key factor is application,design and implementation. I understand there are many roads that lead you to Rome.Inevitably different builders will use various approaches.

Charles

Alot of solid recommendations and yet, not a mention of the speakers in question. The OP hasn’t mentioned what speakers he is using that are admittedly somewhere around 45-50 years old. He hasn’t mentiontioned impedence, brand, whether the crossovers have been updated to specification and whether the drivers are in proper working order. If it was my money, before I spent a dime on anything further, I would think it prudent to have the speakers tested by someone competent. It’s likely there is an amp/speaker mismatch but how do you know? And how can we make appropriate recommendations?

Horses for courses.

I just want to clarify for the OP, that sure- the 6SN7 can be used as a driver with good results to a DHT like the 300B, such as SRPP, DC coupled cathode follower with a negative supply at the cathode, or grounded cathode with local feedback (anode follower). However my point was only that in the Sun Amp (which is very similar, if not identical to the JE Labs 300B SET and also the design posted by Morrison on DIY Audio projects), it is simply using the first section of the 6SN7 as a grounded cathode volt-amp DC coupled to the second triode and then capacitor coupled to the 300B grid. This amp does not do the 300B justice (I’ve built it before). There are many other ways to drive a 300B as well- a C3M pentode, a triode strapped 6V6, a 6EM7, etc. That is not to say that I do not LOVE the 6SN7 (I use it in many of my products) but used properly and not typically being asked to provide large amounts of current sounds best to me. Again, with all engineering there are trade offs and there is no one way to implement an amplifier circuit. I don’t believe economics are the key driven point with a negative supply either, if so, then many designers wouldn’t bother using an inter-stage transformer. As they say, there is more than one way to skin a cat.