Only $2,000 to improve your amp's performance

[Limeman]

How crappy is this amplifier you have in mind?

How about something from QSC?

All kidding aside... could it affect the sound if it were acting as a filter for say... yes, a QSC amp, or something from Mesa or Aguilar... you know... How about a high-quality powered monitor? Could there be any tangible affect?

I'm sorry I ask such rudimentary questions. I know you are an expert and I am genuinely interested in your opinion.

Thanks!

 

[Jim Campbell]

How crappy is this amplifier you have in mind?

i've always wondered what special sauce goes into a $40,000. pair of krell monos,that doesn't exist in say brystons,or macs,and just how steep that old law of diminishing returns graph actually looks....on one hand we scoff at high priced power cords yet spend mega bucks on other gear without a whimper.....i wish there was a reference source for those of us without engineering degrees to sort through all of it

 

[Queg]

Okay, I'll be back after I do some blind testing next week. Kudos to the patience of all the techies. A part of me actually hopes to fail the test.. well besides my wallet there's an ego pride in being willing to admit to an error or misjudgment.

Now, off with the tinfoil hat and on to tube rolling
Or perhaps I better just crank it up and make some noise

 

[bassbrock]

Subscribed for Queg's results.

 

[Bob Lee (QSC)]

How about something from QSC?

All kidding aside... could it affect the sound if it were acting as a filter for say... yes, a QSC amp, or something from Mesa or Aguilar... you know... How about a high-quality powered monitor? Could there be any tangible affect?

I'm sorry I ask such rudimentary questions. I know you are an expert and I am genuinely interested in your opinion.

Thanks!

The minuscule amount of filtering that you could possibly do in a power cord could be done more easily and more reliably with perhaps $1 of capacitors and inductors in the power supply. A competently designed power supply, though, would still have much more filtering than this, especially on the DC rails.

 

[billfitzmaurice]

i've always wondered what special sauce goes into a $40,000. pair of krell monos,that doesn't exist in say brystons,or macs,and just how steep that old law of diminishing returns graph actually looks....on one hand we scoff at high priced power cords yet spend mega bucks on other gear without a whimper.....i wish there was a reference source for those of us without engineering degrees to sort through all of it

I doubt you'd find anything beats the top of the line QSCs in terms of sound quality, so more $ is not going to get you better sound. There's some value in tubes, which offer 'warmth' that SS doesn't. But 'warmth' is oddiophool speak for distortion, so it's not better, just different.
Some monster amps like Bryston and Lab Gruppen are seriously over-built, especially where the power supplies are concerned, and that can be beneficial when used with inefficient/low sensitivity speakers at very high levels. PowerSoft has probably the highest output in the smallest packages, and may be worth their price if you need what they offer. But any amp in the five figure range is just another example of oddiophoolery.

 

[fdeck]

So, there is a small, slim, tiny possibility that what I think I hear with different power cords is not JUST placebo effect, but could also be the result of a little passive filtering occurring in the power cord, audible due to possibly an insufficient filtering/poor design in the power supply of the amp?

Sure. Suppose for the sake of argument that I suspected a component in the amp of letting noise into the output, then I would hook up a spectrum analyzer, measure the noise, then replace the component with a supposedly better or different one, and repeat the measurement.

Now I have left out details about how to do this accurately and safety, but this is the gist of it.

As for your guitar amp, you could have a mis-wired outlet, or a "vintage" guitar amp that is dangerous, or both. Get an outlet tester, and get the amp to a tech.

Edit: I was testing my DIY preamp, and noticed huge noise spikes at mains frequency. Then I discovered that I had accidentally shorted the voltage regulator chip in the power supply.

 

[fdeck]

But any amp in the five figure range is just another example of oddiophoolery.

With apologies to Arthur C. Clarke, "Any sufficiently expensive audio technology is indistinguishable from magic."

 

[Queg]

There's some value in tubes, which offer 'warmth' that SS doesn't. But 'warmth' is oddiophool speak for distortion, so it's not better, just different. .

Sigh. The brittle, sterile sound of a bad SS amp is a result of distortion as well.. a better design will be easier on the ears and thus sound subjectively "warmer" in comparison. In other words, the adjective "warmth" shouldn't automatically imply distortion.

 

[Mark Reccord]

I don't think ESP is claiming that their cable is filtering anything but RF via shielding. In fact they're claiming the opposite; that their cable can pass wide bandwidth signals without phase distortion (more from me on this in a bit). As for the RF, it's conceivable that if RF got past power supply filtering and was sitting on the DC rails, then an amp with poor power supply rejection (PSRR) could intermodulate that RF with the audio signal to cause nonlinearities. This assumes a lot of bad amp design (though I have seen some so-called high end amps that had very very poor PSRR). In the real world, those big filter caps that can effectively filter off 60Hz are a very very low impedance path to ground for RF, especially if they've been bypassed by a film cap, and even if there is a lot of RF riding on the incoming AC signal it never sees the light of day on the DC rail.

I've actually tested some shielded high end power cables (Cardas Golden Reference, Furutech, Crystal) to see if they resulted in less noise on the DC rails and a lower noise floor as compared to a standard IEC. The results were null. No change in the quantity and spectrum of the noise and no change in the IMD of the CD player and amps I tested. The power supplies of the tested equipment were competently designed (one by me). I didn't get to try this with the low PSRR amps I mentioned earlier. So while it is distantly conceivable that a power cable with shielding could make an audible difference, it is extremely unlikely and my experiences certainly lend credence to that.

But like I always say, I'll pass no comment on the audible effects of the ESP cable since I haven't actually tried one (yet).

 

[Limeman]

The minuscule amount of filtering that you could possibly do in a power cord could be done more easily and more reliably with perhaps $1 of capacitors and inductors in the power supply. A competently designed power supply, though, would still have much more filtering than this, especially on the DC rails.

Thanks Bob!

 

[Bob Lee (QSC)]

Sigh. The brittle, sterile sound of a bad SS amp is a result of distortion as well.. a better design will be easier on the ears and thus sound subjectively "warmer" in comparison. In other words, the adjective "warmth" shouldn't automatically imply distortion.

If the output signal is "warmer" than the input signal, or is in any other way audibly changed other than amplified, that's distortion.

 

[Limeman]

If the output signal is "warmer" than the input signal, or is in any other way audibly changed other than amplified, that's distortion.

Got that.

From the dictionary: "A distortion is the alteration of the original shape (or other characteristic) of an object, image, sound, waveform or other form of information or representation".

Not always bad or unwanted, but clearly the average person's understanding of the word is not broad enough.

Thanks again, Bob.

 

[fdeck]

But like I always say, I'll pass no comment on the audible effects of the ESP cable since I haven't actually tried one (yet).

I will.

 

[Queg]

If the output signal is "warmer" than the input signal, or is in any other way audibly changed other than amplified, that's distortion.

Lol, you changed the parameters of my example.
No amp is perfect, they all distort in some way or another.
If the input signal is "neutral", ie not already distorted in one way or another, then an amp that sounds comparatively "warmer" then a harsh, brittle sounding amp may actually be closer in fidelity to the original input signal.

One of the interesting things about the tube or SS debate is that the better the design the less you can tell them apart... the SS amp sounds smoother and the tube amp not overly warm.

 

[Mark Reccord]

Now on to ESP's marketing claims...

Part of the problem with the marketing stuff from the high end cable people is that they're talking about real things (like skin effect) that aren't applicable to the application (why do I feel like I'm channeling Frank Zappa?).

For example, they're making a big deal out of cable inductance and while all cables have some inductance it's hardly a factor in the performance of a mains cable. They've actually stated something in that part that's completely false and that is that large conductors have more self-inductance than smaller ones. In fact, the opposite is the case and it's easily demonstrated. That being said, multiple small conductors, isolated and run parallel will have less inductance (but more capacitance) than a single conductor of equivalent gauge (inductors combine like resistors in parallel), but small conductors inherently have more inductance than large ones. Maybe that's the marketing guys misinterpreting the tech guys but it certainly caught my attention.

All that aside, the 0.8uH of inductance in a 6' long 4x20AWG conductor vs. the 2.8uH in the same length of AWG14 is not important in this application. That amount of inductance will not result in any significant difference in current commutation time at 120Hz or even 20kHz as the time constants for both cables are in the nanosecond range. And that's looking at the cable in isolation. Put it in a system where there's series inductance on both sides of the cable orders of magnitude greater than that of the cable and it's truly insignificant. For example, a typical power transformer might have 10s of Henries of inductance which is 7 orders of magnitude above that of the power cable.

They also seem to be saying that amplifiers draw current from the AC service at frequencies other than 2x line frequency (assuming full wave rectification). This is completely false and is easily demonstrated with a scope.

So while their cable might indeed pass high frequencies without phase distortion, there's no need for it to do that because it only ever transmits current at one frequency. So they're in effect solving a problem that doesn't exist and spinning it as a feature.

 

[Bob Lee (QSC)]

They all distort, but very good ones do so in inaudibly small amounts, like maybe 50 parts per million or less over most of their output voltage range.

Whether the input signal is "neutral" or "non-neutral," the amp that distorts it the least will be the one that's closer in fidelity.

 

[Lukejt]

...

 

[fdeck]

Lol, you changed the parameters of my example.
No amp is perfect, they all distort in some way or another.
If the input signal is "neutral", ie not exceptionally distorted in one way or another, then an amp that sounds comparatively "warmer" then a harsh, brittle sounding amp may actually be closer in fidelity to the original input signal.

If both amps audibly distort, then neither of them has better fidelity to the input signal, though one may have greater fidelity to what you expect or want to hear.

"Do the amps sound different" and "which one sounds better" are separate issues.

 

[Mark Reccord]

I will.

I'm extremely skeptical, of course, but maybe they've hit on something beyond what the physics/engineering community knows about electricity...