All well made good amps should sound the same..

[PeterW.]

Current: Volts x amps = watts = current. V = IR. Ohm's Law. Any good wattmeter will measure current, not voltage, not amperage. It is an uncommon instrument - but by no means rare or unusual. On the other hand a true RMS AC wattmeter does require careful design.

I do actually get it. And if you are suggesting that there are audible differences (in electronics) that cannot be measured or detected with instruments, we are entering into the realm of revealed religion - and that is an entirely different discussion to be had only with sufficient lubrication and at least one referee supplying the snacks.

Nor am I advocating long umbilicals. I am simply stating that there is NO electrical reason against them - and if there are electrical artifacts caused by separating the power-supply from the use, it *will* be a design failure, not an intrinsic (necessary) fault in the concept. The OP might look into that before willy-nilly blaming the distance/proximity.

You are clearly a solid-state person. A mono tube amp driving 8 @ KT88 output tubes will have substantial iron associated with it. And the power-supply will also have some heft. Just a thought to keep in mind. We are not necessarily discussing rational items here, but stating that the concept is absolutely valid.

[Ldg]

No, you really don't get what I'm trying to say, PeterW. And just quoting ohm's law (badly!) repeats the exact trap that I'm trying to point out. It's a huge mistake to think in terms of speakers as resistive, at minimum they have a complex electrical impedance, and in reality also store energy so instantaneous current is also a function of previous history, a function of time.

So no, you don't know instantaneous speaker current just because you know instantaneous output voltage in this situation. And rms power is obviously thoroughly useless as a means of measuring current here, for a whole set of reasons not least because there are many ways of obtaining the same power result.

Anyway, a new 1st - no-one has ever accused me of holding 'revealed religious' views on such topics before, that's so funny. I'm actually pointing out some tangible, verifiable reasons that typical specs and measurements aren't complete here, and miss some significant points when it comes to power amp performance.

Nor am I advocating long umbilicals. I am simply stating that there is NO electrical reason against them

Yes you are, and yes there is !

You are clearly a solid-state person.

Totally wrong. I'm a huge valve fan. I design valve amps, valve phono preamps, have been repairing and restoring them for years, FWIW. I also design solid state amps, and phono preamps. Horses for courses, there are excellent examples in each class. So my perspective on this issue is not without plenty of thought and consideration, and based on experience. Think transconductance. Think current.

I'd stay well away from the casino if you're going to guess like that, PeterW

[PeterW.]

Mpffff.... Speakers are difficult loads altogether. Amplifiers treat them all pretty much the same within their design parameters. Well made amplifiers designed against this sort of thing will pretty much sound all the same within their performance limitations all other things being equal. Amplifiers are what they are, and what they do is pretty basic and pretty simple. To the extent that they do it without adding or deleting artifacts from the original signal, they are successful. Speakers are what they are, and far less basic and far less simple. And they absolutely CANNOT sound like the original signal. They can get reasonably close but like Achilles, never quite there. If I have to get out the rubber mallet, I would define the issue as follows:

Take a _very_ difficult speaker for loading - the original issue AR9. A nominal 4-ohm speaker that drops well below 1 ohm at certain points. I know that, certainly. However, any two given well-designed solid-state or tube amps operated within their performance capacities (not driven overly to clipping) will pretty much sound the same driving _those_ speakers. As they are both facing the same load and both doing the same thing with the same source. Amplifier stability into such loads is critical - but again, well within easily achieved design limits.

A well designed amplifier will both have a sufficiently rugged power-supply without considering capacitance (other than for smoothing) on-board to handle their RMS rating all day and all night. And *should* (hence the term 'well-designed') be able to handle at least a 20dB peak from on-board capacitance, with a 30dB peak not being out of the question. My only-mildly tweaked Dynaco ST120 can do that - and that is perhaps the least capable of my amps.

However it is sliced-and-diced, starting about 1970 and getting more and more so to today, electronics have become more-or-less commodity items with excellent performance achievable using standard technology and standard components and conventional designs. Whether tube or solid-state, the primary differences between them outside of the Crap Zone are in sheet metal, eyewash and quality of peripheral items such as controls and jacks. That there is an entire segment of the industry dedicated to making its victims - err - customers think differently does not make it so. Hence my reference to differentiating between what isn't there, and how it applies to revealed religion. That is much like the difference between a hippopotamus (Behemoth - to the biblical). That very nearly totally transparent amplifiers with very high power may be had at 1970-equivalent prices of $50 absolutely terrifies the high-end audio industry. And they have their propaganda machine running at full speed to "say it ain't so".

You do need to read for content. I used Patrick Turner's amps as an example of _WHY_ separate power-supplies with complex umbilicals may be necessary. And, for the record, when dealing with perhaps 100kg + of electronics, such separation becomes at least convenient if not necessary. And given the success of those items it follows also that there is no electrical reason not to do it. And it also follows that, again with proper design considerations, there is neither danger nor degredation of sound by doing it. I took you for valve-challenged as you seemed to think that weight was not a valid issue. Unless one is into OTL designs - again, another discussion, only this one over beer-and-chips (crisps to you) as OTL is for cheapskates - high-power tube amps (50 watts or more) get heavy, and that weight increases on a sharp curve as power increases - not a linear relationship. Consider a 150-watt tube amp - and the weight will be in the 80 (35+kg) pound per channel range.

For the ultimate heresy - I take the position that tubes are much like vinyl. Enjoyable dinosaurs of which very nearly every other possible medium or device is better. Except that... And it is those 'except thats' that keep me in the hobby and constantly experimenting with it. I have enough core electronics (tube and solid state) to operate eight (8) systems - five of which are active at this time. But I have at least 15 tuners, 12 sets of speakers, 6 phono cartridges with two more planned (the Rabco ST-series is excellent for easy cartridge switching), and three active turntables. Not to mention various CD players, cassette & RtR devices and so forth. Most of which were acquired in some state from less-than-perfect to random-parts-in-a-bag. Swapping out electronics makes near-as-no-difference most of the time (again, I would not pretend that the Dynaco ST-35 will sound the same as the Citation 16). Swapping out transducers, tuners and tape machines - yes, there are LOTS of differences there.

Sorry for being long-winded - but there it is.

Peter Wieck
Melrose Park, PA

[Alec124c41]

Are you implying that a mighty cast-and-machined aluminum faceplate isn't worth the extra $3000 over the plain amp with basically the same circuit?

Cheers,
Alec

[PeterW.]

Are you implying that a mighty cast-and-machined aluminum faceplate isn't worth the extra $3000 over the plain amp with basically the same circuit?

Cheers,
Alec

Heaven Forfend!

Peter Wieck
Melrose Park, PA

[rhomanski]

It's more than just the 1/4" thick aluminum faceplate. It's also the steel covers over the circuit board to keep the motor noise from your turntable out. Or more likely today, your dvd/cd player.

Regards,


Ron.

[Ldg]

Mpffff.... Speakers are difficult loads altogether. Amplifiers treat them all pretty much the same within their design parameters. Well made amplifiers designed against this sort of thing will pretty much sound all the same within their performance limitations all other things being equal. Amplifiers....(..)....what they do is pretty basic and pretty simple. To the extent that they do it without adding or deleting artifacts from the original signal, they are successful.

So says the doctrine of the voltage amplifier driving positive resistive or reactive impedance loads, and to a large extent they do but not quite. Unfortunately, driving current accurately into real speaker loads is at issue, as outined previously on this thread.

Take a _very_ difficult speaker for loading - the original issue AR9. A nominal 4-ohm speaker that drops well below 1 ohm at certain points. I know that, certainly.

OK, let's consider this example. The description of impedance, (1ohm) isn't adequate. That might be the magnitude of impedance, but it lacks a necessary phasor to define a sense and time relationship between voltage and current. And without that, even for a sinusoid which has settled, it's impossible to know instantaneous current when driven by a voltage amplifier.

Secondly, it will be apparent that the magnitude of impedance (1 ohm) is significantly smaller than the dc resistance of the voice coil. This implies that the phasor contribution has an element of negative resistance, at minimum. And by logical extension, actually you don't know whether 1 ohm comprises nett positive or negative resistance overall, since you only know its magnitude. This ought to provoke some deep philosophical questions..........

Then you don't know that your voltage amplifier is not being asked to drive a negative resistance in combination with a reactance. And if you simulate most feedback circuits in voltage amplifiers under such conditions, you'll find stability problems and uncertainty. Quite possibly hasn't been considered in design. Same argument applies as to negative reactance. Instantaneously speaker impedance can be negative, speakers can store energy. Knowing magnitude of impedance doesn't tell the whole story.

So no, conventional voltage amplifiers driving resistive loads doesn't describe it well, and not all voltage amplifiers cope similarly and therefore don't quite sound the same by any means. Even driving the same speakers with the same programme material.

Amplifier stability into such loads is critical - but again, well within easily achieved design limits.

Yes, stability is critical. And no, not necessarily easily achieved when one considers real loads and accuracy of current delivery as a criteria.

And *should* (hence the term 'well-designed') be able to handle at least a 20dB peak from on-board capacitance, with a 30dB peak not being out of the question. My only-mildly tweaked Dynaco ST120 can do that - and that is perhaps the least capable of my amps.

Being able to provide adequate current is but part of the issue. The distinction in action is really about being able to deliver current slew, I', and current jolt I'', and for that to be accurate under conditions where voltage, voltage slew V' and voltage jolt V'' might even be moving in the opposite direction.

I'm firmly in agreement about the proganda machine often being misleading, and would make it absolutely clear that I am not saying that audiophile amps necessarily embrace any of what I'm posting on about. I'm just pointing out one possible, unconventional explanation for why amps might accidentally sound different to an extent, and why speaker matching can be such an ad-hoc affair.

As to long umbilicals, the appropriate rider is 'with proper design considerations' then I agree there can be neither danger nor degredation of sound by doing it.

I took you for valve-challenged as you seemed to think that weight was not a valid issue.

If you search my posts here you'll see that I posted a tongue-in-cheek equation for evaluating power amp performance based on kg per Watt I've designed, built and still use 150W + 150W rms valve monoblocks. But not exclusively, I also use SS amps.

Unless one is into OTL designs - again, another discussion,

I have a box full of EL36s and some sketch designs, maybe one day I'll do it, but transformers can be fine though generally large and heavy when good.