Do amplifiers really sound the same?

[Tony L]

I don't think being able to go down to 1-ohm whilst maintaining full drive voltage is necessary unless driving Apogee Scintillas. Any amp that gets close to doubling their 8-ohm power into 4-ohms is good enough for most nominal 8-ohm loudspeakers, which shouldn't dip much below 5-ohms at minima. They can get into trouble with 4-ohm designs though, which is favoured by American designers and hence the need for arc-welding amperage.

The point I'm trying to make is unless they do double perfectly (and IME most can't even double from 8 to 4 Ohms), then there is measurable imperfection and we are firmly back into the world of subjectivism, i.e. we have found and measured a key reason why amplifiers may sound different in real-world practical scenarios. The hard-line "objectivist" stance portrayed on much of the internet is to my mind utter bollocks as it doesn't even pass scrutiny on it's own terms! It needs to be stated firmly that I'm not siding with the mystical sellers of foo on this argument either, just pointing out that for those of us in the centre ground both extremes look more than somewhat idiotic. Rational and logical subjectivism is the center-ground, the extremes are merely two slightly different types of religion.

An amp suitable for the Scintilla will be ideal with the others, but a gratuitous waste of resources.

Here speaks a man who's obviously never heard a high-power class B solid state amp driving high-efficiency vintage horns! The phrase 'like someone angle-grinding a bin-lid' comes to mind...

 

[Werner]

An amp suitable for the Scintilla will be ideal with the others, but a gratuitous waste of resources.

Allow me to be pedantic, but the Scintilla was mainly resistive. So something driving this successfully does not necessarilly have the stability margin needed for driving a very reactive load.

 

[mudlark]

I've heard a high gain top range preamplifier produce annoying hiss in 89dB/W speakers. (Naim)

This proves that Naim couldn't make good preamps in those days. The hiss never appeared on their measurements, but somehow they relabelled one input into a CD input on the 72. Loads of them were bought by people into CDs when the amplifier is unsuitable for speakers of moderate sensitivity. (IMHO)
The signal to noise ratio into a common speaker wasn't in anyway hi-fi.

 

[Paul R]

The point I'm trying to make is unless they do double perfectly (and IME most can't even double from 8 to 4 Ohms), then there is measurable imperfection and we are firmly back into the world of subjectivism, i.e. we have found and measured a key reason why amplifiers may sound different in real-world practical scenarios.

My point was that your point only applies near clipping and not in a real world scenario, where even your 303 is a reasonable approximation to a voltage source + modest output impedance.

Here speaks a man who's obviously never heard a high-power class B solid state amp driving high-efficiency vintage horns! The phrase 'like someone angle-grinding a bin-lid' comes to mind...

The assumption is low distortion amps...

Paul

 

[Paul R]

Allow me to be pedantic...

Pedantry noted.

Paul

 

[sergeauckland]

Allow me to be pedantic, but the Scintilla was mainly resistive. So something driving this successfully does not necessarilly have the stability margin needed for driving a very reactive load.

Whilst of course that's true, pretty much any modern amplifier that's unconditionally stable does a decent enough job driving reactive loads. Valves are altogether another issue, and it could be argued that they aren't modern!

With highly reactive loads, the amplifier's output impedance is relevant, as a reactive load will present a different impedance at different frequencies, so the amplifier's output impedance has to be very low or the frequency response willbe affected. This is one area where amplifiers can and do sound different, if they don't have a decently low output impedance, say less than 0.2 ohms (including the DC resistance of any 'speaker cable). Pretty much all SS amps will have, few valve amps will.

S.

 

[Yank]

...The hard-line "objectivist" stance portrayed on much of the internet is to my mind utter bollocks as it doesn't even pass scrutiny on it's own terms! It needs to be stated firmly that I'm not siding with the mystical sellers of foo on this argument either, just pointing out that for those of us in the centre ground both extremes look more than somewhat idiotic. Rational and logical subjectivism is the center-ground, the extremes are merely two slightly different types of religion.

Bears repeating.

 

[Robert]

I don't agree at all, especially given the current fashion for very small ported two way stand-mounts which makes for some remarkably inefficient and hard to drive loudspeakers e.g. low 80s sensitivity and sweeping reactive loads with severe impedance dips and spikes. A lot of very highly regarded amplifiers will respond to that in audibly differing ways. If all speakers were say 90db with a perfectly flat 8 ohm load you'd have a point, but they are not. Even quite cheap and compromised speakers can prove quite challenging these days.

You just need enough voltage swing and current, plus a reasonably low output impedance.
Wheel out anything from Cyrus, Arcam, Cambridge, Naim, Audiolab, Nad....it's a very long list.

So long as they don't clip, you won't separate them blind.

Use something that's on paper inadequate in terms of power, say a small 25wpc NAD into your 82dBw reactive load and that too will sound indistinguishable, you just cannot play it so loud.

I do agree that there are some inexpensive speakers around with quite challenging loads, but they only really pose a challenge to tube amps and perhaps some hair-shirt compromised SS stuff built purely for the audiophile market. The answer in such cases it to use a competent, transparent amp which needn't cost more than a few hundred quid.

 

[sergeauckland]

You just need enough voltage swing and current, plus a reasonably low output impedance.Wheel out anything from Cyrus, Arcam, Cambridge, Naim, Audiolab, Nad....it's a very long list.

So long as they don't clip, you won't separate them blind.

Use something that's on paper inadequate in terms of power, say a small 25wpc NAD into your 82dBw reactive load and that too will sound indistinguishable, you just cannot play it so loud.

In all the talk of amplifiers having a personality, a sound, behaving differently into difficult loads, the bit highlighted above needs remebering. Provided the amplifier starts off as a voltage source, to a decently high degree of linearity, then regardless of what the load is or does, provided the amplifiers stays within it's linear region it can't NOT sound the same as any other amplifier similarly within its linear region. Naim, Quad, Cyrus or whatever, will be highly linear until clipping or into pretty difficult loads, and therefore what actually sounds different?

S.

 

[Werner]

pretty much any modern amplifier that's unconditionally stable does a decent enough job

Unconditional stability is the key. It should not be taken for granted, although natural selection tends to eliminate the unworthy.

 

[spxy]

In all the talk of amplifiers having a personality, a sound, behaving differently into difficult loads, the bit highlighted above needs remebering. Provided the amplifier starts off as a voltage source, to a decently high degree of linearity, then regardless of what the load is or does, provided the amplifiers stays within it's linear region it can't NOT sound the same as any other amplifier similarly within its linear region. Naim, Quad, Cyrus or whatever, will be highly linear until clipping or into pretty difficult loads, and therefore what actually sounds different?

S.

Well if just changing speaker cables or interconnect in the system can change the balance of the sound to some degree, surly something as minor as even nature of the binding post on an amp will slightly alter sound balance?

 

[sergeauckland]

Well if just changing speaker cables or interconnect in the system can change the balance of the sound to some degree, surly something as minor as even nature of the binding post on an amp will slightly alter sound balance?

Now you're just being silly!

S.

 

[spxy]

Now you're just being silly!

S.

Whys that?
I've been told multiple time on here that cables act as tone controls.
If so all such connections will do the same throughout...
What measurements does a cable or connector need to have in order not to act as a tone control?

 

[AndrewR]

I am a person who believes that any two transparent amplifier, operating within their design parameters and driving identical speakers, sound essentially identical.

Surely you mean they have to be identically transparent? If so, how do you measure transparency in order to check your hypothesis? What is your point-of-reference?

Andrew

 

[Colin L]

You just need enough voltage swing and current, plus a reasonably low output impedance.
Wheel out anything from Cyrus, Arcam, Cambridge, Naim, Audiolab, Nad....it's a very long list.

So long as they don't clip, you won't separate them blind.

Use something that's on paper inadequate in terms of power, say a small 25wpc NAD into your 82dBw reactive load and that too will sound indistinguishable, you just cannot play it so loud.

I do agree that there are some inexpensive speakers around with quite challenging loads, but they only really pose a challenge to tube amps and perhaps some hair-shirt compromised SS stuff built purely for the audiophile market. The answer in such cases it to use a competent, transparent amp which needn't cost more than a few hundred quid.

If this is the case please explain how 3 amplifiers - a Dartzeel 108B, my old amp Plinius 250 IV, and my new amp MBL 9008A, all excellent measuring amplifiers, can have quite different sonic signatures when driving a relatively easy load - my Wilson Benesch Trinitys.

This was a recent bake-off with me and few hi-fi pals. The differences were clear and easily recognisable, even to my wife

The sonic differences become more obvious with longer listening to one amp, and then a quick revert back to another.

THis thread is like a train wreck you can't help but come back to (usually shaking your head in disbelief).

 

[sergeauckland]

THis thread is like a train wreck you can't help but come back to (usually shaking your head in disbelief).

certianly agree with this last sentence!

S.

 

[sergeauckland]

Whys that?
I've been told multiple time on here that cables act as tone controls.
If so all such connections will do the same throughout...
What measurements does a cable or connector need to have in order not to act as a tone control?

Never believe anything you're told!

As to measurments, you can easily measure the LCR parameters of a cable, they will tell you how the cable will behave when used in any particular AF circuit.

As to connectors, measure the contact resistance and the LCR parameters of the terminals as installed in any amplifier.

It's total nonsense to think that cables of domestic lengths or connectors will have a sonic effect when properly engineered with sensible RCL parameters. If a cable is made with copper (or other low-resistivity metal) conductors, whether twisted-pair or coaxial, all it will do is conduct electricity compl;etely and totally in accordance with Ohms Law and the Maxwell Equations. No more and no less.

S.