Re: The Audiophoolery Thread.
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Watching a speaker distort on an FFT fed from a test mic can be an enlightening experience. The distortion comes on radically and abruptly at all harmonics, with little warning. If a system sounds clean, but edgy on transients, this could be a likely culprit. |
Re: The Audiophoolery Thread.
An interesting valve amp here, make sure you put some sun glasses on before viewing the pictures in detail.
Just to show that what constitutes a good amp varies from person to person and this one could do gold plating. https://newvalveproject.shutterfly.com/ Adrian |
Re: The Audiophoolery Thread.
The front panel looks to have considerable 1950s French styling influences.......
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Re: The Audiophoolery Thread.
I thought myself that its plain UGLY. Bling Bling !
Oh well Just my opinion Joe |
Re: The Audiophoolery Thread.
That is a seriously impressive amp! (the Benchmark that is not the uber-bling valve amp!) I'm not surprised that Laurie Fincham was involved in the design. I talked with him several times when he was at KEF, and well before he decamped to the US to join THX.
Likewise I have not looked into THX's patent (the collaboration with Benchmark led to the AHB2). Halcro's is US patent 5,892,398 Craig |
Re: The Audiophoolery Thread.
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Every now and then someone brings out an amplifier where it looks like nobody checked the crossover distortion. Maybe it was blind cost-paring. How to do it well has been documented well (Self) David |
Re: The Audiophoolery Thread.
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Makes a right b*gger of careful design. The fix is a bit of a cop-out, to bias it so operation sits off to one side. David |
Re: The Audiophoolery Thread.
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They could have done one where the chassis top plate was grand piano shaped. That amplifier looks about as tasteful as Captain Nemo's car... But, really, someone needs to make KT88 with gold plate innards and top layer of the gettering so that the thing can be completed. David |
Re: The Audiophoolery Thread.
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They could have done one where the chassis top plate was grand piano shaped. That amplifier looks about as tasteful as Captain Nemo's car... But, really, someone needs to make KT88 with gold plate innards and top layer of the gettering so that the thing can be completed. David |
Re: The Audiophoolery Thread.
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Makes a right b*gger of careful design. The fix is a bit of a cop-out, to bias it so operation sits off to one side. David |
Re: The Audiophoolery Thread.
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Gold-plating of grids and pins is quite common in special quality valves. I've never seen anybody criticising the watch industry for using gold cases. |
Re: The Audiophoolery Thread.
I think that a significant element of the crossover distortion problem, namely the inherent asymmetry of the Lin quasi-complementary output stage, had been addressed, in terms of cause, effect and remedies, in the late 1960s by several circuit designers, including Bailey (WW 1968 May p.94ff), Shaw (WW 1969 June p.265ff) and Baxandall (WW 1969 September p.416ff.) Baxandall’s graphical explanation was quite clear. He reprised that work in 1977 (in Amos, Radio, TV & Audio Technical Reference Book), expanding it to show that the Quad triples (of 1967) achieved essentially the same result as his “Baxandall diode” of 1969. (Baxandall elsewhere claimed credit for suggesting the triples to Quad, but he did not claim to have originated the idea.)
In 1966, Bailey had noted the transistor amplifiers could be problematical in terms of listener fatigue, etc, and chose transformer drive as the best option at the time. His reasons for so doing were not covered in detail, though, until his write-up on his 1968 fully-complementary design, as mentioned above. In his 1966 article, (WW 1966 November p.542) he also addressed the germanium vs. silicon issue, including the comment: “In fact germanium transistors usually give far lower distortion due to their better linearity”. It would appear that the change from germanium to silicon, whilst generally beneficial, may have exacerbated the distortion issue. With all of that work going on, with key points in the public domain, one might have expected equipment reviewers to have been well-informed as to the need to at least look at the known problem areas for transistor amplifiers. In fact my recollection is that some did, and for example Gordon J. King was on to the crossover distortion aspect in the late 1960s. I also have the impression that some reviewers of the 1960s, such as Geoffrey Horn and John Borwick, made a lot more measurements than were actually published, and probably more than the commissioning magazines had paid for. Certainly, rereading Horn’s Gramophone review of the Radford STA25 left me with the impression that he had “poked and prodded” the machine to death in an effort to find fault. As well as on the technical side, these folk also had credibility in that they were music afficionados and regular concert goers, so were familiar the “original sound”, as it were. Nonetheless, insofar as the reviewing industry generally might have missed the boat in fully observing, measuring, and commenting upon the key issues surrounding the valve-to- transistor transition, they might have helped open the door to what had become “audiophoolery”. Nonetheless, this was also the time when the hi-fi industry moved from niche to mass-market status. That alone would have been cause enough for the snake oil merchants to want a part of it. And the larger market more easily allowed the entry of manufacturers who had unusual or extreme views, both rational and otherwise (e.g. “no tone controls”). A bigger industry invited more magazines, and playing to the unusual and extremes (the tabloid approach as it were) was probably seen as the better business plan in terms of gaining sales. Regarding the importance of the transient behaviour of amplifiers, not revealed by steady-state testing, it would appear that in a general sense it was known before its 1970s rediscovery. This piece at least slightly predates that time: “Good transient response. In addition to low phase and frequency distortion, other factors which are essential for the accurate reproduction of transient waveforms are the elimination of changes in effective gain due to current and voltage cut-off in any stages, the utmost care in the design of iron-cared components, and the reduction of the number of such components to a minimum. Changes in effective gain during "low-frequency" transients occur in amplifiers with output stages of the self-biased Class AB type, causing serious distortion which is not revealed by steady-state measurements. The transient causes the current in the output stage to rise, and this is followed, at a rate determined by the time-constant of the biasing network, by a rise in bias voltage which alters the effective gain of the amplifier.” Cheers, |
Re: The Audiophoolery Thread.
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Cheers, |
Re: The Audiophoolery Thread.
In some of those 'esoteric' speaker cables, it's quite apparent that the manufacturer/designer really bust a gut to endow them with extreme characteristics. It takes something pretty extreme to start affecting the sound directly.
Indirectly might be easier... the famous issue of Zobel diplexer networks becoming unfashionable with some amplifier manufacturers at the same time very high capacitance cables became fashionable. A lot of very expensive smoke got let out of some quite expensive black boxes. David |
Re: The Audiophoolery Thread.
A friend just posted me this - it's for pro-audiophools really, but I think it might raise a smile here.
https://tinyurl.com/y3vc434f "Signal to Noise, fair to both parties - that's a must" ;D |
Re: The Audiophoolery Thread.
Nice one, Mark. I didn't listen to any more than the first few minutes and the lousy muffled audio of his speech had me laughing! The irony of the subject matter was too much.
David |
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That's really very good Mark ! Can anyone identify the speakers or the landline (?) phone on the desk ;D.
Cheers, GJ |
Re: The Audiophoolery Thread.
Did you notice his friend in the first few minutes he describes as a songer singwriter?
Craig |
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I'm glad I'm not the only one daft enough to enjoy it. And I now have a forum signature line :)
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Re: The Audiophoolery Thread.
Hilarious, with shades of Stanley Unwin (who was also a sound engineer).
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