what causes 'thick' sound?

[PreSapian]

i don't know of a better way to describe this sound but it's found largely in vintage amps and valves- that dense saturated notes. of course everyone's interpretation will vary but thick sound is for me just that- thicker imaging, more substance to notes. what are some causes of it? mid-bass hump? slow, bloomy bass? or can it be just from having rich harmonics?

[Mooly]

I know exactly what you mean by that statement...

I believe it's the distribution and level of harmonics... old gear and certainly tube stuff generally produce higher distortion than modern designs but it seems to be pleasing to the ear. It's often predominantly second harmonic too.

I always comment that it's no use having the best specced amp in the world if you don't actually like listening to it. Designing for specmanship has it's own appeal of course but it doesn't always tie in with what we like audibly. I have owned and built so called ultimate/blameless designs and although I tried hard to convince myself it had to be "right" I find I get far more pleasure from a system designed to actually reproduce music rather than numbers

[nelsonvandal]

Second order distortion, high output impedance maybe, but there must be something not fully understood. If you eg take two top performing opamps like OPA627 and AD8610, why do they sound so different? OPA627 is warm, smooth and "thick" and AD8610 is lean and dry.

[LAJ]

latency of the low frequencies as they go thru the cores of output transformers.

[Michael Bean]

High viscosity electrons?
If you're speaking of tube amps it's most likely a combination of low order distortion that many people enjoy and/or output transformers interacting with variation of the speaker impedance. As far as opamp rolling, don't get me started. Some folks just don't get it; you can't randomly substitute one opamp for another without adjusting the circuit around it. The results will be random at best, and no valid judgements or conclusions can be reached by doing things that way. Just my $.02 worth.

Mike

[5th element]

Some opamps can be substituted, the OPA627 and AD8610 being two that can, unless of course you're using one in a *very* specific tailored application that pushes the opamp to its limits.

One thing about older equipment is that large format mid/bass drivers 8"+ we're coupled with tweeters @ high xover points. This causes a large dip in the off axis response around the presence region and depending on loudspeaker could occur from anywhere between 800-3khz. This will also contribute to a more relaxed sound as there's less of what makes a speaker sound 'forward' in the indirect/reflected sound field.

[Michael Bean]

Actually, no they aren't. AD8610 has maximum supply of +/-13volts and the OPA627 is +/-18volts. And even if everything else looks OK, you still need to verify that other issues don't crop up, like supply bypassing works, no oscillation, and so on.

Mike

[Pano]

Having just come back from another acoustic concert, I have to say that the live sound was pretty "thick" and dark. Not the shrill stuff of so much HiFi these days. Maybe the old gear got it right, despite its flaws.

[SY]

Who did you see?

(We're going to Whip In tomorrow to see Lee Barber and Scrappy Judd Newcomb)

[Pano]

It was a chamber music concert. Part of the Eastern Music Festival here in town - 50 years old. Quite a good festival within walking distance.