300b lovers

I will also add that for the preamp, I built one with off the shelf Lundahl transformers and then again, I got Dave Geren at Cinemag to wind me the best small output transformer he could after I showed him the circuit.   Better.......   Very transparent and no coupling caps anywhere!  But plenty of current drive to make cable choices far less important, which is one of the features of the Raven circuit.  Plus the transformer coupling allows for XLR or RCA output and it will happily drive headphones.  Will easily drive even a 10K amp.  So if done right, there are lots of advantages to a transformer coupled preamp.  I can say that I don't miss coupling caps at all, note even the really good ones I was using previously.  So again, for me it is about seeing what was possible and then refining it.

@donsachs 

 So if done right, there are lots of advantages to a transformer coupled preamp.  I can say that I don't miss coupling caps at all, note even the really good ones I was using previously.  So again, for me it is about seeing what was possible and then refining it.

This has been a topic of long standing discourse. Premium grade coupling capacitor versus high quality interstage transformer.

Charles

Yes I am well aware of the debate and tradeoffs in interstage coupling in amps, but I am talking about the output transformer in a preamp here. It has numerous advantages over cap coupled output provided the transformer quality is superb and the turns ratio and design is well mated to the circuit.

I prefer preamps with output transformers too. Luckily, there are decent line output transformers around that are not too expensive, certainly cheaper than exotic caps. But sadly preamps with output transformers are not often offered by preamp manufacturers.

Weirdly enough, both Thom Mackris and Don Sachs came up with the 6V6 driver within hours of each other. Thom was hacking around with his SET 300B amp and swapped in the 6V6 driver and was jumping up and down about it, and Don calls the same day. OK guys, you win, tell me how it’s going.

Thom plays electric guitar and has built his own guitar amp, as well as his 300B SET for his hifi system, so he’s really into tone. The 6V6 is famous throughout the guitar community for its tone. And Don’s a big fan of the 6V6 too. I’d been casting around for a replacement for the unobtainium 45 (in matched pairs no less), and both my friends say the same thing on pretty much the same day. And yes, Don and Thom chat on the phone on a regular basis. I think they have an ESP thing going.

My NiWatts started off as 6SN7 --> 6SN7 --> 300B.  You could think of the Reichert as being the launch point, although through the years, the only remaining similarity between the two designs is two tubes (the 6SN7 input and the 300B).

I was pondering switching to a 45 for a driver for quite some time, and thought, why not start with a 6V6?  I have to say that I can't find a compelling reason to change.

I let this amp sit in a 90% state of completion for several years.  I had too many irons in the fire. 

Anyhow, Lynn's conversations with Don motivated me to pop the hood and finish the job.  The spooky thing about this process is how many things the two of us discovered in parallel, and even more spooky - within days of each other.

I could swear that an audio muse was injecting thoughts into both of our heads.

The fact that we settled on so many similar design concepts (while the two designs are so radically different) still has me shaking my head.

The most recent "coincidence" occurred last Friday (literally within hours of each other, according to Lynn), where we made parallel revisions to our 300B cathode's circuit.

... Thom @ Galibier