300B Tube Amps with 15/16 Watts Per Channel?

I read something years ago that stuck with my and I have always tried to heed.  A really good tube amp is the sum of three things.  How good is the circuit, how good is the power supply, and how good is the iron (transformers).  Those who favour OTL designs can ignore the iron.  Of course there are other factors at play such as how much distortion there is in the tubes chosen, but if you use decent tubes and pay serious attention to the main three points, you should end up with a very nice amplifier.

I rebuilt hundreds upon hundreds of vintage tube amps and preamps before I started making my own.  You could tell the good ones before you even started.  If there were serious compromises in power supplies or transformers, then no amount of replacing old parts with better modern ones would ever make them great amps.  You could tell the great amps from the schematic and quality of parts used.

So my advice is the build the best power supply you can, use the best iron you can, and find a good circuit.  I exclusively build push pull amps.  I don't build single ended or parallel single ended circuits.  I understand there are those who favour such designs.  I only use regulated supplies, and I also only use tubes with larger plates, and as many directly heated tubes as I can.  Those are my choices based on the main rules above, and moving beyond the "conventional" designs I built for years.  The conventional amps I built are very nice, but the latest full balanced circuits are far superior to my ear, and more costly to build.

So my advice on a good 15-20 watt 300b or other amp, is to heed the three main rules, and build a good push pull one.  If you can DIY you will save lots of money.  There are many great parts from companies like Neurochrome, the Rod Coleman regulators favoured by a pretty large camp, read Barola valves site for some great info...particularly on drivers.  There are lots of places you can check out for a DIY 300b project.

Or you can simply use speakers that will run happily on 10 watts and build a very simple (well not that simple actually if you consider power supplies and transformers, etc..)  push pull amp with no feedback that is flat from 20-20K with very low distortion to drive them and be happy:)  Using  DHTs...  to each their own.  The problem lies in supporting people that need more than 20-25 watts/ch.  If they have made that speaker choice so be it.   We all have our paths to audio nirvana....

@donsachs I find a mark of the best systems is they don't sound loud even when the are- relaxed at all volumes. On that account, I've found that even with very easy to drive speakers (98dB, 16 Ohms) you tend to use a lot more power than one might think!

But at the same time I've also found that the better the amp is at making clean power, the better its first Watt is, that such an amp can be quite convincing.

These two things might seem opposites of each other but they are not.

I designed a little 5 Watt PP amp about 4 years ago that was meant for my bedroom system, because I couldn't find a compact amp (this one can sit on a sheet of notebook paper with room left over) of the same power that wasn't junk. 5 Watts doesn't seem like much (although for a desktop, bedroom system, headphones or a system with really efficient speakers its plenty), but compared to a 5 Watt SET its quite a lot since it has a lot more usable power and is overall more musical than any SET (for example it doesn't sound 'loud' which many SETs do even though they don't make much power) I've heard. I was finally talked into producing that amp about a year ago.

It uses feedback. But one of its tricks is that it didn't need feedback to sound just fine. I mostly used it because it had too much gain (with only 3 tubes/channel).  

There are oodles of 20 to 35 watt push-pull amps from the classical era of the 1950’s through the 1960’s. Most of the "mods" of these amps are nothing more than updating the coupling caps, which is a good idea anyway with an old electronic product.

@lynn_olson I refurbished an Eico EL84-based amp recently. That one didn't have good iron so output power was rolling off at 30Hz and distortion at bass frequencies was high. You do  have to be careful about what vintage amp you try to 'renovate', 'update', whatever... many of them are built to a price point since back then, they were manufactured as a commodity so output transformer bass response is a likely candidate for cut corners.

@atmasphere I agree on the vintage amp transformers.  The citation II amps were legendary and would be flat down to about 8 or 9 Hz at full power.  The Sherwoods were generally pretty good as well as the Scotts and Fishers.  The Eico stuff can vary.  They were definitely built to a price point.   The best little EL84 amp I ever heard was the Sherwood.  If 10-12 watts/ch was enough, the little Sherwood integrated amp was quite enjoyable to listen to.  The Macs and Marantz amps also had very good iron.   The little Eicos, Heathkit, and others of that ilk were all over the map for quality of iron.  Honestly there are fabulous transformers wound today if you want to work with a winder and spend the money.  If you buy an off shelf Hammond, or Edcor or whatever you can certainly build a decent amp, but you will not the get the inner detail you will from a more expensive transformer.   You get what you pay for.   That is why Chinese amps for $1500-2000 are decent, but not great.  Good iron is over $1000 for a stereo amp....

Hit post too soon..  Great iron, not just good iron.  The kind of transformers that give you goosebumps if used in the right circuit.   If you use a Hammond, you will never hear what the circuit can do....

 If you use a Hammond, you will never hear what the circuit can do....

@donsachs Great for small guitar amps though!