Sound Quality Vs. Measurements

[FrankWW]

The question is why different amps seem to have had such a large impact on the sound for a given pair of speakers.

I'm thinking that a reasonably well designed and manufactured speaker should not sound a whole lot different with different amps if they're competently designed and made.

But you're using dinky speaker that has a dome tweeter crossed over at 2k 2nd-order the manufacturer says. Well hell, any kind of serious program material at any sort of reasonable listening level is going to present that speaker with problems. And any sort of irregularity from an amp, even a "good" one, is going to exacerbate those problems isn't it?

I think I understand your project with regard to amplifiers but, gosh, I'd think you might get more pleasure out of it if you were hooking your improved amps up to reasonable speakers.

[Wavebourn]

The problem is Frank, your "reasonably well designed" contains presuppositon for "designed for any amp". No such "Resonably well" design criterion. If design is competent it follows rules and limits. Set of amps, in terms of their parameters, have to be defined, before calling them "Reasonable".

Like,
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */


Also, degree of "seriousness of a program" has to be measured. I have not seen any seriousinessmeter in my life.

It is the main problem of the topic, "Sound Quality Vs Measurements".

[FrankWW]

The problem is Frank, your "reasonably well designed" contains presuppositon for "designed for any amp".

You're right. of course. Any utterance has to have presuppositions.

Mine are pretty simple. I think a good speaker system, no matter how high the SPL, won't sound objectionably "loud" even if run by consumer gear like Pioneer or Denon. That's not exactly "scientific" or formal, but it's definitely empirical

I think dinky poo speakers like TVR's with dome tweeters aren't going to make most amplifiers shine at reasonable listening levels. They can't - the dome tweeter craps out. (I suspect the woofer does also). So how is he ever going to know what sound problems to attribute to the amp or to the speaker?

[dvv]

Originally Posted by FrankWW

You're right. of course. Any utterance has to have presuppositions.

Mine are pretty simple. I think a good speaker system, no matter how high the SPL, won't sound objectionably "loud" even if run by consumer gear like Pioneer or Denon. That's not exactly "scientific" or formal, but it's definitely empiricalI think dinky poo speakers like TVR's with dome tweeters aren't going to make most amplifiers shine at reasonable listening levels. They can't - the dome tweeter craps out. (I suspect the woofer does also). So how is he ever going to know what sound problems to attribute to the amp or to the speaker?

(Bold and red by DVV)

And here you've hit the nail on the head with a sledgehammer.

This corresponds EXACTLY with my own experience. A high quality speaker, in terms of loudness, stays the same on low as on high SPLs, it only gives out more of.

If the sound starts to change as the volume goes up (within reason, i.e. within the speaker's nominal power handing), then something's wrong with the design. This is, of course, assuming the amp doesn't give up the ghost, or is overdriven.

On the other hand, far too many amps do exactly that, their sound changes as the volume increases. It may not be a radical change, but it's there, and one can hear it. Typically, they tend to become harder and sometimes harsher sounding, while being still way below saturation and, God forbid, clipping levels.

I'll make so bold as to say that most commercial units do that, their sound changes as the volume goes up, and it's always for the worse. Of course, there are commercial products done well enough for that not to happen, or even if it does, for the effect to be really minor.

Harman amps, at least those higher up the model scale, are blissfully free of that effect, and I swear on my immortal soul I have no ties whatsoever with that company. Nothing but simple, old fashoned respect. Denons usually come out good as well, as do some Sonys, again, higher up on the model scale. There are sure to be others as well.

Big amps are also not always free of that effect. Quite a number of higher powered amps (say, 100 wpc and upwards) don't sound too good at lower levels, they need some power output to come to life.

[ThorstenL]

Hi,

Originally Posted by dvv

If the sound starts to change as the volume goes up (within reason, i.e. within the speaker's nominal power handing), then something's wrong with the design.

If we agree on this premise we have two issues.

The first is that you are not accounting for for the change in frequency response (re. equal loudness curves) with SPL in the Human ear.

The second is that most HiFi Speakers have woefully inadequate thermal design, leading them to compress. Three to four dB thermal compression is nothing unusual for "HiFi" Woofers. In a true three way speaker this compression will affect mostly the bass driver so it will "turn the mid-bass down" as volume goes up.

So if the bass is boosted enough at low volumes, it may give more of an impression of unchanging frequency response with SPL changes while in fact the frequency response changes a lot. Another part is that at higher levels the damping of the driver will change due to the voice coil heating.

That is before we even look at distortion.

Equally, these jokes sold commonly as "HiFi Dome Tweeter" tend to compress strong signals in their passband (massed Brass?) and will show severe HD if driven hard.

Common "HiFi" Speakers are really and truly the polar opposite of any speaker that offers "High Fidelity" and instead are dynamic frequency dependent compressors, distortion generators and frequency response unequalisers. Defending them as offering any fidelity approaches laughable.

Which does not mean you cannot like the way they sound. That and "high fidelity" are rather unrelated topics.

Ciao T

[gk7]

Originally Posted by ThorstenL

... Three to four dB thermal compression is nothing unusual for "HiFi" Woofers. ...

Are there any measurements available which show this effect at
domestic listening levels ?

[gk7]

They are:
Hot Stuff: Loudspeaker Voice-Coil Temperatures Page 2 | Stereophile.com

"... So I strongly suspect that, for most hi-fi users—those who don't habitually wind the volume control to its highest position and indulge in PA listening levels—thermal compression is a paper tiger. ..."

[ThorstenL]

Hi,

Originally Posted by gk7

Are there any measurements available which show this effect at domestic listening levels ?

Pray tell, what are "domestic listening levels".

Past that:

MONITORS versus HI-FI SPEAKERS Part 1

MONITORS versus HI-FI SPEAKERScPart 2

Originally Posted by gk7

They are:
Hot Stuff: Loudspeaker Voice-Coil Temperatures Page 2 | Stereophile.com

"... So I strongly suspect that, for most hi-fi users—those who don't habitually wind the volume control to its highest position and indulge in PA listening levels—thermal compression is a paper tiger. ..."

It is nice to see such safe conclusion from such a thoroughly researched article, with such a large sample size + variety and such rigerous and extensive experimentation.

I normally respect Keith Howard's work, however he hit that ball way out of the ball park.

While I would not suggest that the Sound on Sound article gives enough volume of data to make reasonably safe conclusions on the matter, the article in SP has real measurements but only single data points.

Try measuring an LS-3/5 for example.

Ciao T

[SY]

Originally Posted by ThorstenL

I normally respect Keith Howard's work, however he hit that ball way out of the ball park.

Unintentionally funny.

So, do you have contrary data to share?

[ThorstenL]

Hi,

Originally Posted by SY

Unintentionally funny.

So, do you have contrary data to share?

Soundstage publish some thermal compression data, generally not at high SPL's though, so the data is of limited use.

Otherwise, in Pro Audio it is a very well known phenomena and extensively documented.

Just because we suddenly have "HiFi" Speakers the laws of Physics do not take a holiday nor do Speakers suddenly stop to act according to them...

In fact, most HiFi speakers are constructed quite poorly in terms of thermal management.

For one fun example, the Magico Mini is generally considered an uncommenly dynamically capable speaker for it's size. It will come as no surprise that it has a woofer with some of the best Thermal management I have encountered in "HiFi"...

I could also mention some of the poorest thermal design I have seen, but it would look I am deliberately targeting people's Kit, so I shall not.

Ciao T