Vintage, yet Modern
My amps are typically voiced for country, rock and blues. Those are the styles I play on guitar so are best suited for me to design. I've worked on high gain amps before but I've decided to focus more on those styles for my lineup.
Almost all my amps build off a classic base but have been modernized in some way. Many have more gain and circuit features to better handle more gain. I play almost exclusively without pedals so my goal is to have an amp that can give me a good palette of tones just plugging in. I realize this is restrictive to most players and design my amps to be pedals friendly as well.
One of my goals is to keep the number of knobs and switches to a minimum. While this can sometimes give a lot flexibility, I feel like too much can really choke down an amp. Some of my two knob amps are amazing to play with just the volume and tone on the guitar.
My focus has been on low power since I started building amps, mainly because I never needed much more volume than a screamin' 5 watt amp can put out, but also because it seemed the only 5 watt amps I knew about were garbage. The best way to make the Epiphone Valve Junior sound good is to throw everything away except the power transformer (questionable still) and build it from good parts! Unfortunately that puts you at the price of a Fender Blues Deluxe, but man they sound a lot better driven and have an actual usable cranked volume.
I've found that especially on small, single-end amps there is no substitute for a good output transformer. I simply do not like the way they sound if that isn't right, and I've tested a LOT of them over the years. I've finally found the ones that I like the best for the designs I've built. I'm now EXCLUSIVELY using Mercury Magnetics for my output transformers, and for many of my power transformers as well. They are a bit more pricey, but I won't put my name on anything less.
The other big piece of your tone is the speaker. I typically build and sell head units, but I can and will do combos of any amp. Determining an appropriate speaker can be an expesive and complex problem. For most of my building I've been working with Celestion speakers - mainly four models: Vintage 30, G12H Anniversary, G12M Greenback and Alnico Blue. These have been classic low-power speakers and will handle most of my amps. I'd recommend running two Alnico Blues with an 18 watt amp (they are 15W rated) although people have run them singly. These speakers also pair nicely in 4x12's or 2x12's, I particularly like a Vintage 30 and G12H or Alnico Blue and G12H as combinations. Recently I've been testing a few more Weber Vintage Alnico speakers for a different kind of vibe. I like them with most of my amps and you may too! If you have a speaker preference of your own, I encourage you to try, but make no guarantees on the results!
For vacuum tubes I've chosen to stock them with JJ Electronic, Electro-Harmonix, and/or Sovtek. While there are perhaps better sounding tubes out there, I've found these to be very good sounding and reliable all-around. Consider that almost every production amp now comes with cheap, Chinese tubes and these Russian made tubes are quite an upgrade. It is also quite easy for the owner to experiment with different manufacturers in the future.
All of my designs and builds use polyester film capacitors wherever possible because I like the way they sound. I've typically used Sozo capacitors for the ultimate tone but I am now using CDE M150 stock unless you want an upgrade. Where needed, I use the highest quality electrolytic capacitors I can from Sprague ATOM, F&T, and/or JJ Electronics.
I've decided to also include variable voltage, or in other words variable power on my 15 to 18 watt amps. This allows them to reach a volume level similar to a 5 watt amp and still retain good tone. I recommend using a small, speaker motor attenuator for going to any less volume. Weber Speakers makes some very good models that gives you a very active touch and true(r) tone down to very low volume i.e. less than 1 watt audio power. All my 5 to 10 watt single-ended amps will work with a Micro Mass and 12 to 18 watt push-pull amps with a Mini Mass.