Is an Amplifier considered best based upon THD level?

[vmscbe1974]

Friends

I was having a discussion with a friend of mine and he said the THD percentage measures the Quality of the amp where if it is less than .05% its the best sounding amp because it gives more warmer sound of the mid range....... is it true? then is any amp with a specification of 0.1% an average option?

Let me know.
regards
srinivasan

 

[Audio_Freek]

Sir,
Personally I dont feel the THD would give the quality of the Music reproduction.Its a measurement of Distortion.The More its Low its best. My present Amp is 0.15% THD and they sound smooth in Mids. I had Yamaha Amplifier before, If i Remember the THD was 0.8 which never could to my current Amp in Mids or High whats so ever.

 

[Mohanv]

In my experience, 1% THD is barely perceptible only with the Finest Electrostatic speakers. 3% THD is becomes audible with most cone type speakers.

All amplifying devices such as transistors, JFETs, MOSFETS, Electron Tubes etc., are not linear. However, they can be operated in their narrow linear region. But then most mass produced amplifiers are designed with the 'Watts per dollar' in mind. So the amplifying devices are operated at their maximum power dissipation levels. Negative Feedback (NFB) is then applied to reduce distortion. This can be local NFB or Global NFB.

The higher the NFB, the lower the distortion and reduced dynamic reproduction and less warm sound.

Regards,
Mohan

PS: Audio Freek has a nice set of speakers; Yamaha NS 1000. I have listened to these speakers many, many times .... the most satisfying sound was with a 50W tube amplifier such as the old Audio Research, Jadis and Copland power amps. If these amps are expensive, then, you could consider a tube preamp.

 

[Fantastic]

Is an Amplifier considered best based upon THD level?

No.

It's not as simple as that. Distortion should be below audible levels but the spectrum of the distortion is very critical. Good tube amps particularly have a fair amount of distortion but they usually have monotonically decreasing distortion figures. As frequency goes up ( of the distortion ) the levels keep dropping. Additionally they generate 2nd harmonic distortion which sounds 'warm' to the ears. They sound 'nice' to the ears but are technically not accurate like modern solid state amplifiers. Low distortion needs to go along with decreasing distortion at higher frequencies.
A SE amp with 0.5% distortion 'could' sound better than an average solid state amp with say 0.05% distortion if the ss amp has significant HF residual even though it's low in level. The 2nd harmonic of the SE tube amp ( main part of the 0.5% distortion) will make it sound 'warm' and nice for many people. Not all tube amps have 0.5 % distortion levels ! Some have very low levels too ! Especially tube preamps.
Ideally a very good tube amp and a good solid state amp should sound identical. There will be very low distortion and no HF crap to colour it !
Some people love how the tubed SE sounds and others hate it. You take your pick....as usual. That's what audio is all about......so far !