SoftwireEngineer wrote: > Ralph, I know the technology behind these (I am a EE/CS major). You are > misinformed about the Panny and TACT. > Jitter is not a silly thing. It is the main thing in digital playback.
http://www.head-fi.org/t/486598/testing-audiophile-claims-and-myths the harbeth challenge.. Here is a challenge then. (from Alan Shaw, harbeth designer....not taken up yet...wonder why??? If, in a controlled experiment with all variables accounted for (incl. differences in frequency reponse and within the power range appropriate to the amps) under instantaneous A-B relay switchover, driving any Harbeth speakers, if you can positively identify an amplifier by sound alone, I will give you, FOC, a pair of brand new Harbeth speakers, up to and including a pair of M40.1 in any veneer you fancy. I am quite confident that under controlled conditions, these fabled amplifier differences disappear and that I will never be parting with my money! However, I don't have the time to play around. You have to conceive of the test, design the switch over system and bring it to us here and we'll cooperate fully. There are plenty of examples of carefully constructed tests over the past 30+ years to draw on that meet my critera, and every one of them comes to the same conclusion. As far as this 'amp matching to Harbeth speakers' issue goes, it is a non-issue. As dead as the dodo. I cannot comment on the amp matching for other speaker brands. We take care to make our speaker an easy load: other speaker designers may be less consumer-focused. NO CORRESPONDENCE PLEASE - CALL ME WHEN YOU HAVE THE WHOLE PLAN EXECUTED! Amplifiers should be selected not for "sound quality" (whatever that is) but for facilities, design integrity, durability, after care and likelyhood of being able to source service parts in 5 or 10 years. Also, if you're really serious, a quick peek at the financial standing of the brand might tell you if they are likely to have the financial resources to weather the economic downturn of the next few years which is effecting the whole consumer electronics sector. Some of the most likely surviving (UK) brands rarely advertise, rarely exhibit, have relatively old-fashioned designs, use standard parts, have been around for a generation and are rock solid businesses. They deserve to be respected and supported because they will be there to look after you in 10+ years. There are some very difficult times ahead for the consumer industry: now is a time to be cautious. Alan A. Shaw Designer, owner Harbeth Audio UK I keep stumbling across things in the most unexpected of places .... just as well I don't trust my audio memory! Some posts back we introduced the idea of an instantaneous switch-over box containing heavy duty relays which under foot switch remote command, will divert the audio signal from A to B. It can be used in several different ways because relays are non-directional and the terms 'input' and 'output' are interchangeable. In this example from several years ago, I was working on the design of the NRG bookshelf speakers. I'd arrived at two very different crossovers in my simulator, named X1 and X2. You can see from the (poor quality) picture that these crossovers have different components in different places and a different crossover frequency yet according to the simulator model the end result is a virtually identical loudspeaker frequency response on axis. But would they sound the same or would there be a sonic winner? That the simulator cannot tell. I really don't like situations like this where there may be a technically superior solution, but for lack of care or time or listening fatigue the less good solution is picked. Considering that I do all development listening in stereo (that's unusual I'm told, even the BBC designers listened in mono to one speaker) I'd have to disconnect and reconnect two wires to each tweeter, two wires to each woofer and two wires to each amp output - a total of 12 connections to be made to connect either a pair of X1 or X2 crossovers: in fact, to make a change over there would be 24 wires that had to be swapped. Assuming that I moved really fast, paused the music, rushed over the the speakers and made the twenty four connections at the fast rate of 10 second each, it would be 10 x 24 = 240 seconds minimum before I could be back at the hot seat and playing music again. That's far, far, far too long a time gap to draw a reliable impression about whether X1 or X2 sound best. You may as well flip a coin. The solution was simple, and took a few hours of construction time. A switch-over box to which the pairs of X1 and X2 input and output were permanently wired as were the tweeters and woofers and amp connections. At the touch of the foot switch, the two tweeters and two woofers were driven from the X1s or in the other position, driven from the two X2s. Change-over time about the blink of an eye. And the result? Interesting. The simulator was right (of course) that the resulting frequency response was, subjectively, virtually identical. Listening to one pair for ten seconds or so, or until some interesting feature of the music made you wonder how that would sound in the other position, I must have switched between them twenty of thirty times over as many minutes before the very subtle real sonic differences started to show themselves to my ear/brain. Those extremely subtle differences - which amplifier exponents claim are 'night and day' to them could never be positively identified with one or two minute gaps between switch over. One circuit did sound very slightly better and we went into production confident that the best one had been chosen, and also that if the same test were run today, the outcome would be the same. The proper evaluation of all and every audio component (or recording) really should be done under instantaneous conditions or the outcome is, at best, questionable. It's satisfying turning in at the end of the day assured that you have done the best job possible and can truly justify why. I do understand that to consumers disconnected from the mysterious design validation process this seems a cruel, cold, unemotional way of comparing A with B. And maybe it is. I doubt that one audio designer in ten uses such a method because the outcome is rarely flattering to his hard work. ------------------------------------------------------------------------ TheOctavist's Profile: http://forums.slimdevices.com/member.php?userid=52700 View this thread: http://forums.slimdevices.com/showthread.php?t=96407 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/mailman/listinfo/audiophiles
