Modern gear....

[nickb]

...

BTW - I'm happy to answer questions about the HD amp if there are any...

What I find most interesting is that the behavior of the AOT design, basically a differential buffer on the LTPI, is very different (for example output impedance is about 0.4 ohm as opposed to 40 ohms) from a tube transformer coupled PP is well received by the press. It begs the question as to what the essential characteristic(s) is/are that appeals to them?

[SoulFetish]

What I find most interesting is that the behavior of the AOT design, basically a differential buffer on the LTPI, is very different (for example output impedance is about 0.4 ohm as opposed to 40 ohms) from a tube transformer coupled PP is well received by the press. It begs the question as to what the essential characteristic(s) is/are that appeals to them?

So the output is a voltage source?

[Helmholtz]

So the output is a voltage source?

Judging from the schematic in the link it's a tube amp up to the PI with a symmetrical/balanced SS power stage in bridge mode and floating speaker output. SW5 allows to switch in a 4 Ohm resistor in series with the speaker.

For comparison : The output impedance of a JTM45 is around 2 Ohm depending on "presence" setting while an AC30 is 70 Ohm (both with reference to 8 Ohm output).

[The Dude]

I'm curious if anyone else here has tried the Quilter amps. I borrowed one for a while to tinker with and was thoroughly unimpressed. It wasn't even something I'd consider gigging with.

[Jazz P Bass]

I'm curious if anyone else here has tried the Quilter amps. I borrowed one for a while to tinker with and was thoroughly unimpressed. It wasn't even something I'd consider gigging with.

Which model did you borrow?

[The Dude]

I believe it was the 101 Reverb.

[Leo_Gnardo]

I'm curious if anyone else here has tried the Quilter amps. I borrowed one for a while to tinker with and was thoroughly unimpressed. It wasn't even something I'd consider gigging with.

One of my customers got a Quilter, he was very excited to have it. 200 watts, WOW! When he brought it over to show me, my review was a thorough "meh..." World's most inefficient speakers - IIRC it was a couple of 8's - sounded dull as dishwater and not much volume available for 200W. This guy usually played his Tele thru a hot rodded Vibrolux Reverb outfitted with JBL K110's, you could drill holes thru steel armor with that combination. I just don't get what attracted him to his Quilter. Maybe it didn't hurt his back so much to lift it?

[glebert]

For small modern amps that have impressed me with their sound, I like the ZT lunchbox and the Boss Katana stuff. A guy I play with has a ZT and just gets amazing tone, then again he also has a pedalboard that weighs about as much as a 212 tube combo amp. Jammed with a guy with a 50w Katana, had his Hagstrom LP plugged straight in and he got really great tone.

[Zozobra]

The Orange CR series is pretty legit. Preamp is opamps and a few fets. Poweramp is whislte clean power. Someone traced it and posted the schematics here. You could coble one together with whatever poweramp you wanted for not a lot of cashola and it'd weigh next to nothing.

[J M Fahey]

In principle save a lot by using light 1/2" plywood, the thinnest one which can still be nailed or screwed without splitting and a single 12" Guitar Type Neo speaker.
Forget PA speakers, you NEED the cereal box thin cone and the light short voice coil which give you the much needed 9 to 12dB peak around 2500Hz or so ... what Quilter misses big time.
No "150W" speaker either; 70/80W tops, think a standard Legend or C12N or Greenback equivalent but with Neo magnet.
Add a Class D power amp and supply and given those savings you now build any preamp you like ... even a tube one.
You can feed it from an SMPS or even a small toroid .

It will sound same SPL and *similar* flavour to any 2 x 6L6 + 1 x 12" combo at less than half the weight.
Maybe even 1/3rd , go figure.

Plan B: build the light cabinet with the light speaker and a built-in light amp+supply, so you can use it NOW, and experiment with preamps, pedals, even simulators until you find one you like.

Plan C: buy a Katana 50 and transplant it to your own lightweight thin plywood cabinet.

[uneumann]

It begs the question as to what the essential characteristic(s) is/are that appeals to them?

I've been trying to understand this myself. I didn't know how things would turn out since AOT was an experiment. I have several theories, two of which I can argue from evidence so far. First is the absence on explicit nfb. Yes, the ss followers are intrinsically feedback stabilized, but there is no nfb loop from output back to some input. This should reduce damping and allow the spkr to behave more freely, as in tube amps. Second, the cathode follower "power tubes" actually "see" a reflected load impedance. The transistor gains are limited so the cathode output currents change as the load currents change. This is potentially important since it's also what happens with a transformer stage. The tubes react to the reflected load currents and voltages, which get complex for spkrs. These effects are completely missing if you just feed a tube preamp into a traditional SS amp. Heavy nfb damps the spkr and there is no reflected spkr impedance.

There may be other reasons why the AOT sounds the way it does, but this is all I have so far.

[nosaj]

In principle save a lot by using light 1/2" plywood, the thinnest one which can still be nailed or screwed without splitting and a single 12" Guitar Type Neo speaker.
Forget PA speakers, you NEED the cereal box thin cone and the light short voice coil which give you the much needed 9 to 12dB peak around 2500Hz or so ... what Quilter misses big time.
No "150W" speaker either; 70/80W tops, think a standard Legend or C12N or Greenback equivalent but with Neo magnet.
Add a Class D power amp and supply and given those savings you now build any preamp you like ... even a tube one.
You can feed it from an SMPS or even a small toroid .

It will sound same SPL and *similar* flavour to any 2 x 6L6 + 1 x 12" combo at less than half the weight.
Maybe even 1/3rd , go figure.

Plan B: build the light cabinet with the light speaker and a built-in light amp+supply, so you can use it NOW, and experiment with preamps, pedals, even simulators until you find one you like.

Plan C: buy a Katana 50 and transplant it to your own lightweight thin plywood cabinet.

Speaking of lightweight plywood. At our cabinet shop we get 1/2 luan birch plywood, 3/4 birch plywood and 3/4 Maple plywood.

When it is delivered I've noticed it all used to come from China, when the tariff junk started then it started coming from vietnam, then last month it started coming from Indonesia. Odd thing is the 3/4 birch is now the same weight as the 1/2 birch. I can't explain it but my body is happy since one person one sheet of plywood.

nosaj

[Tony Bones]

And solid pine weighs even less. Why does no one believe me when I say this?

[nosaj]

And solid pine weighs even less. Why does no one believe me when I say this?

Kiln dried solid pine is super light with a nice resonance.

nosaj

[Tony Bones]

Kiln dried solid pine is super light with a nice resonance.

nosaj

And it's a lot stiffer than plywood as well.