"Warm Sounding" Solid State Amplifiers

I currently own the NAD M2 and as much as I really like it, I would never consider it warm, technical would be a better way of describing it. My front end is digital so it meets my needs just fine. If I was using a TT, this is an amp I wouldn't buy.

Many years ago I owned a Bedini 25/25 and that is an amp I regret selling. It was what I considered warm in sound but hot to touch. Class A power meant a lot of heat!

When I was thinking of selling my M2, my thought was to go towards NAIM for that warm sound. In the end I thought there was nothing really wrong with the M2 and it sounds great with my Harbeth 30.1.

My favorite thing about the amp is I don't need a separate DAC. My system looks nice and clean, very minimalist.

Good luck with your search.

Csontos, it does not matter if it is live or reproduced, our ears listen for those harmonics (which are always there) regardless. We can't change that!

Quite simply, the application of physics to design equipment to honor our human hearing/perceptual rules will result in better sounding equipment:

What we *can* is change our approach to how we are going to playback recordings; i.e. design the equipment with intention to simply not make those distortions to which our ears are the most sensitive. These distortions are IM (which might also be termed a special form of 'inharmonic distortion') and the higher orders of harmonic distortion, the 5th and above.

(Our amps (Mk3.2) are full power out to about 300KHz since you asked.)

Those designers like Nelson Pass and Charlie Hanson (Ayre) that have sorted out that feedback can be dispensed with are also demonstrating that such leads to a more musical approach. Norman Crowhurst is required reading for anyone designing audio circuits. About 60 years ago he wrote about how the application of loop negative feedback in an amplifier that does not exhibit higher ordered harmonic distortion (like an SET which might have the 2nd, 3rd and 4th harmonics) might well reduce the lower orders to vanishingly low levels, but in the process higher orders (starting with the 5th harmonic) will be added going clear up to the 81st harmonic! In addition, intermodulations can be introduced at the feedback node in the amplifier.

The result is that the noise floor is fundamentally altered. In an amplifier that has no feedback, the noise floor is hiss, not unlike that of the wind and the sound of water moving. Not by coincidence, our ears are adapted such that they can hear into such a noise floor, some say as much as 20 db but to be safe 10 db for sure; this is the *one* exception to the human ear's masking rule. This allow us to hear detail that exists below the noise floor of the amplifier and if you think about it, essential to our survival.

When loop negative feedback is applied (per Crowhurst) this noise floor is altered and while it might sound the same, the peculiarity is that our ear's making principle is in full force- we cannot penetrate that noise floor, so the detail below that point is lost.

This is why amplifiers that employ loop feedback seem to loose low level detail in which room ambiance and imaging detail in the rear of the soundstage resides. To hear this occur, you must start with a recording that has plenty of depth, then you can audition that difference between the two approaches.

Since the application of loop feedback also adds harmonics, this is why any amplifier using it can sound brighter as well, since our ears sense those added loudness cues.

Nelson Pass has a wonderful article on distortion on his website: https://www.passdiy.com/project/articles/audio-distortion-and-feedback; Nelson is one of the leading designers worldwide.

Thank you as well, Blackcloud. That is very helpful information.

Yes, It's a well known article. But it doesn't really bring up anything we don't all know already. At least those of us 50+. I get all that. I mean I believe it, I remember the 70's:). So what I think you're saying is, it boils down to the question "how much is too much?" IOW, the devil is in the details. Enter the subjective nature of our hobby. I always knew diminishing thd with decreasing power was the way to go. That's what makes sense. It's a shooting gallery out there right now and the prey is ripe for the picking. However I think I have a handle on what the rules are.

"Enter the subjective nature of our hobby. I always knew diminishing thd with decreasing power was the way to go. That's what makes sense. It's a shooting gallery out there right now and the prey is ripe for the picking. However I think I have a handle on what the rules are."

After reading some of your posts, I can't help but think that you're focusing way to much on the rules of audio, and not enough on the music. If you continue going in this direction, you'll just get more and more frustrated. You're never going to have all of your questions answered, so you might as well make the best of it and not worry about a number on a piece of paper.