All Amps Sound the Same....

Onhwy61 - I'm only saying to avoid products that measure too well for the price, because something has to give and often it is sound. Soulution monoblocks look very impressive but I'm more withing Rowland 625 range.

I agree, that some kind of dynamic test would help not only designers but also buyers to make right decisions, but so far I can see many key specifications missing or without reference point. We all learned, one time or another, that equipment tested with sine or square waves behaves completely different with music. Often not a good specification but rather company name is wort paying for. I ended up buying small Rowland amp knowing that Rowland for over 20 years produced only very good amps. My next amp is likely to be Rowland.

I'm all for better testing, being frustrated with trial and error while pieces are often not available for trial (heavy or expensive). To add insult to injury some dealers start charging for in store demonstration. Well, it is what it is.

Onhwy61, the analogy with motorcycle racing is one I must applaud you for!

This is the argument I've been making here and there on this site over the past year or so. Quite simply, the move of measurements from algebra to calculus.

Previously, in motorsports, the means of measurement you enumerated dealt with the steady state - algebra. As you also noted, because of the intense competition (and available processing power) they were forced to transcend that realm of operation, and now deal in the real time measurement of acceleration/deceleration, forward/reverse, stop/start, etc - calculus. At that point, folks are able to digest this data, make adjustments, and ultimately implement things which yield tangible benefit to the craft.

It would be nice, as you say, that this transition also took place in audio. Unfortunately, I must say that I am not as sanguine as you are about how this will proceed in our niche. In my opinion, with few exceptions, this lies beyond the ability/capability of the designers currently in the high-end audio hobby.

I posted this in another thread, and thought it was relevant here.

****I know this is a crazy question but is it possible that the length of dissimilar conductors with varying dielectrical properties can have varying effects,positive or negative,in terms of introducing,eliminating,or altering interference?**** - Fripp1

I don't have the slightest clue. But your comment suggests something that is overlooked by many on the "numbers" side of the isle. We crave answers and explanations. But why are we assuming that we are asking all the questions that need to be asked? In my estimation it is short-sided and arrogant to think that established electronic-design standards address ALL that is going on in an electrical circuit. Is the science community not regularly discovering new things,and debunking previously accepted notions? Why should audio/electronics be any different? Add to this the fact that we are not talking about race cars or wine. The affected "product" is being asked to deal with the reproduction of an ART form. Complicating matters is the fact that we are talking about an art form that is not static (some visual art). Music is not only a constantly moving target,it has as a core ingredient the expression of emotion,and often involves the sonic result of human interaction. To think that numbers as understood today can be a complete picture of what can be going on in the electronic record/playback realm,and how that might affect our perception of it is silly.

Frogman - nobody is talking about complete picture but rather about step in right direction.

As for the wire and interference. Lets for a moment assume that we're talking about speaker cables. Interference, usually high frequency, can be capacitively or electromagnetically coupled. In either case length of the wire makes difference. Let assume further, that we're dealing with electromagnetic pickup. At very high frequencies output of the amp has high impedance being also an input since feedback i connected there. Cable becomes an antenna. Antenna becomes practically ineffective when it is shorter than 1/10 of the wavelength. Let assume that we're dealing with 10MHz radio station nearby. Tenth of the wavelength is about 10ft. Using cables longer than 10ft exposes your amp to electromagnetic pickup of everything below 10MHz. It is not big help for very common 10ft cable since there are many radio stations above 10MHz, but at least eliminates a lot of mid and shortwaves. It can also eliminate other sources.

Reverse situation. Imagine that your class D amplifier is polluting speaker cables with 0.5MHz frequency. In order to effectively radiate it cable would have to be 200ft long. Your ICs can still pick it up capacitively but most likely they have shield and are in some distance.

I don't know of any positive effects of making cables longer. It will only introduce more interference by extending bandwidth increase capacitance and inductance. Unless you believe, that cable "enhances" sound longer cable is worse cable. 0.5m IC is better than 1m IC in spite of what dealer tells you (he has 1m in stock). Exception is digital cable when you want it either very short (few inches) or at least 1.5m long (but not much longer) to avoid first reflection on impedance boundary to interfere with the edge that is producing it thus affecting clean transition thru threshold point causing jitter (noise in time domain).

Even shielded cables are exposed to electromagnetic pickup. Non-magnetic shield (aluminum foil, copper braid) in reality does not protect against electromagnetic pickup but picked up signal, being high frequency travels on the outside of the cable - shield, because of the skin effect. Effective field in the center (where wire is) is zero. Skin effect is diminished at lower frequencies but they won't be picked up unless your IC is long enough to be 1/10 wavelength antenna. That's why even shielded cables should be kept short.

To be more clear:

Instead:
"Using cables longer than 10ft exposes your amp to electromagnetic pickup of everything below 10MHz"

should say:
"Using cables shorter than 10ft protects your amp from electromagnetic pickup below 10MHz"

My logic had better days. Russ69, sorry for posting on this thread. Just wanted to help.