Tube Amp for Devore O/96

I have some research to do I suppose as I don’t know Class A from Class AB or what a pentode is.

Triodes get their name from having three elements- cathode, grid and plate. Pentodes have two more grids as a method of increasing efficiency, but they trade off the additional power they make for linearity. Triodes are about as linear as any amplifying device can get. That is why they can be used to make an amplifier with no feedback.

Class A is where the tube or transistor is conducting throughout the entire waveform. This is usually the most linear portion of the device’s operating curve. AB trades off greater efficiency for linearity. You will see this tradeoff a lot in audio. In class AB the device does not conduct thru the entire waveform; at some power level only one of the two devices (AB is not used in single-ended amplifiers) stops conducting and so the circuit draws less power. Usually class AB amplifiers will need some feedback to make up for the reduced linearity.

I really recommend that if you have a larger room to go with some kind of push pull amplifier. You’ll need the extra power! Its hard to make power and bandwidth at the same time- meaning that with single-ended amplifiers typically 7 Watts is the most power the amp can make and still have hifi frequency response. With push pull you can get amps that make 100 Watts before you start to run into this problem, which in both cases is caused by the output transformer.

There are class A triode amps that are push-pull and there are class AB pentode amps that are push-pull. So there can be a bit of variance in the sound as a result. Usually the pentode amps will have feedback while the triode amps often run none. Feedback can be really tricky because it can add distortion of its own while otherwise suppressing the innate distortion of the amp- leading to a harsher and brighter sound. Those that prefer the zero feedback amps usually do so on this basis- and often with the claim that zero feedback amps are more ’involving’. There is some scientific basis for such a claim, having to do with how the brain processes music. Its normally done in the limbic centers; otherwise transferred to the cerebral cortex if the brain detects an issue with the sound; if that happens the music can lose its emotional context.

Ralph I’m surprised you didn’t explicitly support my mention of your S-30. I know the 0/96 may dip slightly below 8ohms in a few frequencies, but might you have any opinion on how the S-30 might perform with the O/96?

@blisshifi I appreciate the mention bit am also careful about the forum rules. I think the M-60s a better match in most rooms just because of the power; in this particular case @flipturn mentioned he has a larger room so the power will be appreciated.

@flipturn That speaker is easy to drive so you have a wide range of amps to choose from. Its not efficient enough (unless you have a small room) for SETs (which should not be run past about 20% of full power in order to avoid excess distortion) unless you have a really powerful one. The problem with those is they audibly lack bandwidth.

If you are set on tubes look for a triode amp that is push-pull. That will get you the power you need; triodes have linearity that pentodes and tetrodes don't. They allow the designer to build a smoother and more detailed sounding amp due to lower distortion.