Tubes vs. solid state.

Minorl, of course there are electric cars too, and energy storage systems that are a lot better than the internal combustion guys would have you believe.

There have been improvements in amps in the last 50 years. There are new topologies that did not exist in the 1950s or 60s. So even if the parts had not gotten better (which they have) there would still be progress.

A lot of that progress comes out of the understanding of how the human perceptual system works. IOW we are not going to make progress if we design something to look good on paper, but the paper rules fail to take in how we hear sounds. Dr Herbert Melcher (famous in the world of neurochemistry) has done some recent studies that show that the more an audio playback system violates human perceptual rules, the more the processing moves from the limbic system to the cerebral cortex.

Atmasphere, do zero feedback solid state designs share the same benefits as zero feedback tube amps ?

Thanks

Oh shucks, I must really be tin-eared, because I have never detected any correlation between 0-feedback and the sound I like, in any amps I heard, tubed and SS alike.

Guido,

I have. And although my sample is limited, I have found a very strong correlation between zero feedback designs and my long term satisfaction with the equipment.

Non-zero feedback designs that I have dealt with and discarded because of aural issues:

1. Rowland capri
2. Rowland Synergy 2i
3. CJ MV-60SE
4. Linn Klimax
5. Nagra PLL

Besides the CJ above, which I lived with for a year, I got rid of the other equipment within a matter of months, if not weeks.

Equipment, I have had a long term relationship with:

1. CJ Premier 14 (3-4 years)
2. Nagra VPA (bought it and never got rid of)
3. Ayre A7 integrated
4. Ayre KX-R
5. Dartzeel nhb-108

I did not start out with any biases towards non-zero feedback designs ... in fact it was the other way around. I would always (and still do) peruse the distortion measurements of equipment in Sterophile, Soundstage, and I had a strong bias against zero feedback designs, as they showed up poorly in the measurements department.

My ears simply lead me to the equipment that I now have.

Of course it is also possible that I am highly suggestible, and I am the one with the tin-ear.

Pinkus, the only issue with transistors is that without feedback, they will make more distortion than tubes will. However, if the design is competent, the higher orders will not manifest nearly so much as they will if feedback is applied. Its my opinion that in time we (as designers) will sort out what must be done to make them work properly.

One of the best amplifiers I have heard is transistor, made by Ridley Audio. It was zero feedback and class A and fully differential. It employed a heater to heat the output devices to a fairly high temperature (and then regulated the heat) and made as much heat as any tube amp of the same power. The amp made 100 watts and cost about $100,000 for a pair (they could drive a 1 ohm load); a bit pricey for my blood but proof that the extra distortions of transistors can be tamed if handled right.

For the time being as I mentioned earlier, it is a lot easier to use tubes to keep the distortion down. It might be cheaper too. If one looks at the whole amp/speaker thing from the point of view of obeying human perceptual rules, the issue of higher output impedance of zero feedback amps becomes moot- that is 'what is' so you deal with it in the design.