SET Lovers, what's the one solid state amp you love(d)?

In your case with exciting class-D amp success, does this somehow suggest you are eventually planning on shutting down your tube amp manufacturing side of the business, i.e. "are on life support"?

@decooney That depends on sales. But if we can make a class D sound as good as tubes I suspect others can too. But there are other issues that anyone dealing with tube amps should think about. We all know about the war, which has increased tube prices worldwide.

But there is also the fact that class D is making its way into the guitar world. I'm not talking about those cheap 'modeling' amps either- but good quality class D amps, often with a tube input section. They might make 50 to 200 Watts and weigh under 20 pounds. Many guitar players these days do not rely on the overdrive sound of their amps for their unique 'sound'; they get that from their effect pedals instead. So a guitar amplifier these days doesn't have to be a 100 Watt Marshall.

Its happening slowly right now. But as more class D product makes it into the guitar world, tube sales in that market will dwindle. Audiophiles may not realize it, but tube sales worldwide are driven by the guitar market, not the home audio market. In ten years I suspect the guitar world will look a lot different- if you have a 50 Watt guitar amp, its a big deal that it might weigh only 15 pounds instead of 75!!

@atmasphere Thanks for the note. All makes sense, and as they say, we’ll see how it goes. I’ve been following Class D for the past decade. A few buddies who play guitars switched with a few holdouts still running tube for lead guitars.

On a related note, I remember when the HD Radio tuners came out, people went out and bought them. Folks got fired up, we’d see note’s how the conventional FM radio tuners were dead forever!!! Outta here!, blah blah. HD radio and streaming came to automobiles too. Quite a change for the auto and audio industry. Seemed to make sense in autos for sure. For home use, a few holdouts still liking old FM more. When HD radio came out it seemed like it was still missing something.

While owning both, from time to time I still fire up the conventional Magnum Dynalab FM radio tuner. And what’s odd is how conventional FM radio still sounds as wonderful as ever. There are times I actually prefer its sound over today’s streaming for a different type of listening. Reminds me of tube amps and what is at question here.

Also watching closely how people some buy the latest generation of Class D from AGD, NAD, Atma, and others claiming its "there" now, and then how many of those same folks put them up for sale and return to Tube based amps again a year or two later. Very interesting to see how this continues to unfold next 2-5 years.Got the mono block tube amps playing great music and close to 3D type sound as I type this now.

Hey, maybe if everyone else goes Class D, there will be a glutt of tube amps and supply of tubes out there for the rest of us diehard holdouts to pick up for a great price. Wishful thinking maybe, and looking forward to it either way, good times! :) 

But there is also the fact that class D is making its way into the guitar world. I'm not talking about those cheap 'modeling' amps either- but good quality class D amps, often with a tube input section.

@atmasphere My bandmate has a very negative impression of Class D for guitar amps but he’s open.  Do you have any recommendations for some good ones that are already out?  Thanks!

Would you say that in your experience with Class D speaker matching is easier or more difficult?

Compared to a tube amp, easier! Most speakers are designed to be 'voltage driven' which is to say that the amplifier is supposed to be a 'voltage source'. A voltage source will put out the same voltage regardless of the load. To do that a very low output impedance is required. This is stupid easy with class D and difficult at best with tubes, so in theory a class D amp should be a lot easier to match with a speaker. There are limits, such as extremely low impedances which will reduce the Q of the output section filter in a class D amp, but its pretty well-known that tube amps don't like really low impedances either so that's pretty well moot.

The only exception might be ESLs. Some ESLs, like Sound Labs, have a pretty significant impedance peak in the bass, and expect the amplifier to be able to make the same power into that peak as it might in the mids and highs where the impedance is much lower. In general a voltage source doubles power as the load impedance is cut in half which also means that the output power is cut in half as the load impedance is doubled. IOW a voltage source might have its 8 Ohms power cut in half or in quarter with such speakers (Sound Labs have a 30 Ohm peak in the bass region). So tube amps can work out well on such speakers where a powerful solid state amp won't be able to make power.

In addition, the capacitive load of ESLs can mess with class D amps that are not of the 'self oscillating' variety. This is because the capacitance of the load is in parallel with the inductance of the output filter of the amp, setting up an electrical resonance which can result in ultrasonic oscillation. I know of at least one respected class D amp that suffers this trait and can fail in this application (with possible damage to the speaker as well if not properly protected). Our class D is self-oscillating and so does not have this problem.

@soix https://www.epifani.com/ makes some interesting bass amps. Powerful and quite lightweight with some heavy hitters playing with them. You can see where this is going...