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In Reply to: RE: not only unanswerable, but irrelevant posted by pictureguy on July 30, 2014 at 18:55:31
I wouldn't presume to argue against any of your points. I'm certainly no authority on the semiconductor manufacturing process (I've spent my working life as a technician). Perhaps, part of the high cost of the Pass amps covers rejected output devices. Frankly, I have no idea, but Pass does match the devices for each amp to exceedingly close tolerances. Even if the lot code is essentially meaningless, the tight matching is still meaningful.
I should also qualify a statement I made regarding the quantity of paralleled devices in the output section. The X150 uses different devices from its bigger siblings. The X250 has 32 output devices. So, compared to the X250, the delta is 16 for the X350 and X600 - a 50% increase instead of 20%. There is a theoretical advantage to that and measurements suggest that also translates to practical advantages.
I still maintain that comparing the slew rate of those devices to anything in the audio realm is like comparing a lightning strike to a sprinter and, as Dave pointed out, they're never really 'off'. I can honestly state that I regret selling my old X350 - it was a superb amplifier. I'm not saying that I'm at all unsatisfied with the valve amp which replaced it, but the difference in sound between the two isn't exactly overwhelming. I think that's high praise for the X350. While my Phi 300.1 was at VAC for repair and some upgrades (all at zero charge), I tried using my X150 and hardly listened to that system - same power rating (at 8 ohms), but it was anything but equal at the task of driving my 3.7s (which are spared the grunt work of sub 60Hz bass reproduction - well, that's the crossover point @18dB/oct). Even with my MMGs, I thought the X350 was significantly better than the X150 - but, that's probably not the best comparison (it would have been interesting to compare it to an X250).
I didn't intend for this to become a hot debate. I just find the position (which has been forwarded by numerous individuals) regarding the difference between the members of a series favoring the juniors hard to support (based on my understanding of the theory and my experience, albeit limited), at least for such amps as the Pass X-series. I admit that my personal experience could just as easily be affected by my belief as others who hold the opposite opinion. Perception is a brier patch.
This is an interesting hobby. Pick any issue in audiophilia and opinions will always be divided. Who is right? That's probably impossible to answer. I tend to gravitate to engineering theory, in which I do have some background (and I have a deep love for science). As long as the discussions don't get ugly, I enjoy a bit of debate. That's the best way to expose the foundations of opinions. In the end, we don't have to agree on this one - not that big of a deal. I just wanted to express my opinion on the matter, so I did.
Follow Ups:
Breir patch, indeed! No question about it. Some of these debates is like jumping Neckid into a patch of Poison Ivy. Or more to MY experience, picking figs off my tree without wearing long sleeve shirts. Man, what a RASH from that sap and whatever. Must immediately SHOWER.
Anyway, my point was simply to come up with a REAL or Realistic explanation for what some have noted, that being in a series of amps which are essentially scaled UP as you go 'upline', some actually prefer the lesser powered amp.
I HAVE to give those guys as much credence as the hobby (as a whole) seems to give those who note all sorts of differences, from Insulators (teflon=good / polystyrene=bad) or perhaps WIRE (Silver is bright sounding) or any of a dozen OTHER things of various degrees of scientific proof to outright wackiness. There are various levels of expanation ranging from 'reasonable theory' to 'let's have a s`eance!' Name your poison, stake your claim or whatever.
I floated an idea some time ago about biamping with radically different amps. My thought was that the time it takes a signal to go THRU the amp would have an audible effect. Sure enough, I got little support, but than I spotted a post from Davey which seemed to support the idea. Progress? !
cheers:
Too much is never enough
I don't know if I "supported" that concept or not, but I might have pointed out that indeed there are some amplifiers that do have built in group-delay (and other characteristics) for varying purposes. The Sunfire amps being the classic example...to facilitate the operation of the tracking power supply.
If you utilize disparate amps when bi-amping the world is not going to end, but when performing subjective evaluations it's important to understand any differences so as not to extrapolate incorrectly.
You have to really be careful when forming objective conclusions based on subjective testing. There's a couple of members here who do it incessantly. :)
Dave.
Dave
I am assuming you include me in the speculative extrapolation group. I will say that it is true that is my first tool to investigate anything. Then you delve into the physics in parallel to finding other people's observations and designer's pet theories. From there I go to picking modsters and DIY'er minds and go on to more listening experiments and figure things out or start a project, or post the speculation online for comments and to generate more ideas, or drop an issue as either too big to tackle or postpone giving it more attention.
The main limit is that I don't want to become an electronics engineer or audio engineer (or maybe I do?...). But I still want to be able to improve my own system's performance and advise friends on improving that of their systems.
"The main limit is that I don't want to become an electronics engineer or audio engineer (or maybe I do?...)."
You should. It allows to see through much of the self deception, intellectual dishonesty, and nonsense that pervades this industry.
If your first tool of investigation is speculative extrapolation then you're starting from a premise that can immediately lead you in the wrong direction....in a variety of different ways. :)
There's nothing wrong with subjective evaluations, but you can't make any objective conclusions from it. And any subjective conclusions you make from it are only valid for you and no one else.
Dave.
Unfortunately Davey, just about every industry is like this these days. Too many people hired to spin and BS their products rather than hired to make them better, combined with an uneducated public that typically does not spend any time really researching things before they buy. This industry is particularly difficult because it is technical and few understand any of the guts of these things at all (although my kids are learning about it at the elementary level at their STEM school).The A/V industry pales in comparison to the mattress industry. Talk about lying manipulating crooks.
I though this was about my first pair of Maggies....
Edits: 08/04/14
There is little alternative for an audiophile. There are aspects of sound quality we don't have effective measurement methods for so we can't rely on by the book design guidance principles and technical evaluation alone. We also need to be able to weigh the results of particular tradeoffs for our purposes.
There is no choice but to speculate on what technical aspect results in a paricular aspect of SQ being one way or another. Hence the constant need to change items in the chain.
Finally, there are simplifying assumptions behind the engineering equations that enable quantitative design that some designers try to take into account when designing with particular components in mind. Pass is one in particular who pays attention to these things in his white papers and we presume he does so in his designs, particularly for the First Watt designs.
Sorry:
It was Satie who made a related comment: QUOTE:
Davy (UK) had a listening based observation on coherence going with biamping vs single and found that for him there was something that sounded wrong with the use of different amps on bass and mids on 3.x models. For my own observation it is an issue, but careful matching of amps and XO will solve it and what little time issues remain can be adjusted for by ear with relative distances to the drivers (toe in - on the order of < <1").
The 'relative distances to drivers' remark speaks to me of time delay to fix the 'problem' of amp latency.
Too much is never enough
Yeah, that's not me. Sorry.
That guy is in the UK somewhere....I'm not.
Additionally, everything I read from Satie I take with a large grain of salt. :)
Dave.
You noted that the discrepencies between amps could often be adjusted for by panel toe which changes the distance from the listen to the various drivers…making up for 'lead' or 'lag' of a signal.
I'll see if I can find the entry again……I saw it maybe 45' ago.
Too much is never enough
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