It looks like a debate to me.

Rather have feedback from Industry professionals vs hobbyists

Pros vs Joes, huh?

Why? Are all of them in agreement with each other now?

OP > If alienating people is not your forte, hang in there. It will be soon enough as you are definitely headed in the right direction by candidly dismissing our humble faceless & ofrten selfless pundants.

Or maybe This is just a tad shortsighted post whose intent is to infuse mor activity from manufacturers and or designers into the fray. Well, good luck with that.

Whenever a pastime revolves around personal opinion, be it faceless those of our hobbyists or a our designer's opinion, it is tainted by subjectivity and as such is a thing as malleable as human morality and as capricious as the winds

IOW, to which individual at the end of the day, will you subscribe simply on faith be it producer or end user?

If I want to get candid experiences, knowledge, or insights on something I know nothing about, or not very much, and Iíd not care to send off letter after letter to this makerís offices or that one, the quickest path then is to glean information from those who have actually fixed a transmission, built a house, recarpeted their living room, or here, put together a few or even many various audio arrangements in likely quite different rooms, locations,etc. and on various levels of investment.

Additionally, users, members, or just the run of the mill enthusiasts often do not have anything to gain from imparting their EXP via associated or various threads, as might those whose product sales are how they keep their refrigerators filled, their lights on at home, and their children fed.

OJT ëhands oníí first hand EXP or training used to be considered the most practical   form of education and in many arenas, still remains the best teacher.

Lets reviewÖ
makers, designers manufacturers and dealers all have a visible and valid motivation to further their professional interests, albeit many of that ilk on these pages do not share their technical eXP as self serving advisements, or tips.

But then really, whoís to say which is extolling the truth and who is embellishing or slandering facts?

Time, application and your own outcomes will validate other folks input/feedback on what ever topic you chase provided you pursue the path or paths others supply you their EXP.

OrÖ are you the sort which only follows those whose superficial credentials or social wcircles intimate they are elete, even if arguably so?

It costs nothing to ask things around here, and it costs less to receive the feedback this forum promotes. Within it are numerous highly skilled, experienced well intentioned individuals whose routine motivation is to help another.

as viable in any darkened web forum there will be that element of nay sayers and dissidents, so assimilate accordingly.

some members here are current or former technicians, designers, producers, dealers, engineers, etc., often found in the guise of mere members of an online audio oriented public forum.

Iíd not wish to alienate these from assisting me going forward as cases may be down the road.
given the price one pays for information embedded on these pages, this joint is a veritable gem!

enjoy!

Kaitty's system: Grado SR60 or 80 utterly mediocre headphones with the foam ear cushions removed and a Sony Walkman CD player. Right Kaitty? There might be green sharpie on the edges of the  CDs which certainly elevates this system to true High End so yeah, he knows what's what.

Wolfie is a master debater.

Remove the "de" and you are spot on.

Since I was not invited (for good reasons as you will see) to the seminar I'll just make this post-


It should not be a debate. If you have a tube amp that 'measures poorly' yet seems to sound just fine (as has often been seen in the pages of Stereophile) and an amplifier that measures just fine and is really 'neutral' but not particularly musical then you have two amplifiers that sit at the opposite spectrum of the same problem, which is distortion and what to do about it.

In this regard with **all** amplifiers the sound of them is all about how they distort.


In this regard each has chosen a different path. On the one hand, a tube amp that 'measures poorly' is probably not running any feedback to suppress distortion, and one might want to know why not? The answer is that feedback adds distortion of its own, and what it adds is highly audible in the form of higher ordered harmonics (at low levels) and IMD. The human ear is keenly sensitive to both types! OTOH, the ear **isn't sensitive to the lower orders (2nd, 3rd and 4th), which is why that tube amp measured so poorly as it probably has much more of these in exchange for keeping the higher ordered stuff inaudible.

The solid state amp employs feedback as it has to to prevent it latching to the power supply rails (which would cause it to have a lot in common with a rock) and to allow it to be linear. So it inherently is much lower distortion, but now most of that distortion is of the form to which the ear is keenly sensitive, and comes off as brightness and harshness, since the ear converts all forms of distortion into tonality.

Again this should not be a debate! The common problem here is that neither amplifier has enough gain bandwidth product and so is a set of compromises. Tube amps, unless OTL (Output TransformerLess) usually have poor gain bandwidth product. Solid state amps usually do much better in this regard. But neither has enough- and this is what that looks like: without enough gain, you can't apply enough feedback so that the application of feedback allows the amp to correct not just for simple distortion but also the distortion caused by the application of feedback! Did you get that? Its sounds recursive because it is. Feedback can correct for itself if **enough** is applied. That value seems to be a minimum of about 35dB and 40dB is better.


But that means that the amp has to have a lot of gain so that once you blow 35dB or more away you still have enough to work with the preamp and speaker, so the open loop (no feedback) value should be at least 60dB!


Now we come to the other bit of that gain bandwidth product thing: bandwidth. Sure you can make a tube or solid state amp with that much gain, but when you run feedback around it there is an enormous possibility that it will oscillate. The reason is that when there is gain there is also phase shift caused by limited bandwidth- the more gain you add, the more the bandwidth is compromised. The phase shift can thus cause negative feedback to become positive feedback at some high frequency- and then it oscillates. A related idea in amplifier design is that of 'phase margin' which is to say that if by the application of feedback the amp oscillates, it has insufficient phase margin. OTOH phase shift causes the feedback to become positive rather than negative. 


So one way to deal with this is avoid feedback. You avoid brightness and harshness because the lower ordered harmonics mask the higher ordered harmonics. But the amp will measure poorly unless extreme steps are taken to suppress it by other means.


The other way is to stare down the gun barrels and add the feedback- now it 'measures' well but it has a brighter and harsher presentation than real life.

IOW **neither** amp is right! So this shouldn't be a debate. Instead we should be looking at the measurement standards- its obvious that since the ear is insensitive to lower ordered harmonics that they should not have the same value in the measurement as higher orders; IOW the various harmonics should be weighted. But in addition, the 2nd and 3rd in particular can mask the presence of the higher orders, so those harmonics should be in attendance in order to allow for something that sounds like music instead of electronics. But our current measurement regime takes little of that into account. In a nutshell, in this regard one of the most important aspects of human hearing (the fact that the ear senses higher ordered harmonics to gauge sound pressure) is ignored in order for the spec sheets to look 'nice'.


So this should not be a debate so much as a seminar on informing the public what is really going on. Sadly, it will probably just be a debate.