I am pretty sure we are able to measure anything we need to evaluate audio electronics, nowadays. The recipe is easy:
- make all distortion products below -120dBr at any amplitude and any audio frequency and any load
- make S/N of the whole chain better than 100dB/re1Vrms/20kHz unweighted
- make reasonably high slew rate and clean transient response
- apply for all PSU products same criterion as for distortion
- make it EMI proof
- make low output impedance
I am sure that such audio chain is transparent enough and does not need improvements or "better parts". The problem is that the criteria will never be met with tubes or no NFB designs, so artificial themes will rise again and again.
- make all distortion products below -120dBr at any amplitude and any audio frequency and any load
- make S/N of the whole chain better than 100dB/re1Vrms/20kHz unweighted
- make reasonably high slew rate and clean transient response
- apply for all PSU products same criterion as for distortion
- make it EMI proof
- make low output impedance
I am sure that such audio chain is transparent enough and does not need improvements or "better parts". The problem is that the criteria will never be met with tubes or no NFB designs, so artificial themes will rise again and again.
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Did such a thing exists in audio ?
But, may-be you mean GNFB, where only matters slew-rate ?
Well, i'm not sure i follow you on this track: "we are able to measure anything we need".
Here is a nice line amp, witch can run both in CFA and with no GNFB. With distortion/noise numbers witch seems to meet your criterias in the two modes:
http://www.diyaudio.com/forums/solid-state/235695-no-nfb-line-amp-gainwire-mk2.html#post4088885
Surprisingly, while components are the same, builders all reports sensible differences in listening experience between the two modes. And they seems to express them on a concordant way.
We are measuring continuous signal (sin or square), music is made of transients, transistors are subject to thermal effects...
Or, if you prefer, we are measuring vertically, we are listening horizontally (for musicians, at least ;-)
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-120 dB, or 0.00001%, working into say 2 Ohms, with a phase shift of -45 degrees is a VERY tall order, Pavel. VERY, VERY tall, especially if the nominal 0 dB VU level is something like 150W/8.
Not saying it's impossible, mind you, but that would need to cost a pretty penny to achieve. Do tell, I'm sure you must have worked it out at some point, how much does your 150W/8 amp cost in parts alone?
I beg to disagree with your view that such a system is transparent enough if it meets the above criteria. I have heard a few Accuphase amps which came near to those criteria, were very stable and reasonably powerful, but unfortunately not transparent enough compared to some much cheaper amps.
And, irritatingly enough, I have heard a few amps which were nowhere near those criteria, yet managed to sound much more transparent than their counterparts - an excellent example would be the original Otala/Lohstroh amp.
@Esperado - yes, no GNFB amps do exist and always have, a more recent example would be Densen Beat 100 amps. They claim to have zero GNFB, all of it was relegated to idividual amp stages as local NFB.
Another good example are almost all Harman/Kardon designs. They do use GNFB, but in extremely low numbers, such as 12-17 dB typically. And they do sound a little different from their competitors, I believe because of this, since they advocate a very wide opan loop bandwidth, typically out to 80 kHz and above. Examples would be HK 680 integrated amp (from 1999) and Citation 24 (from 1998, I think), both using just 12 dB (3:1) of GNFB.
Another good example are almost all Harman/Kardon designs. They do use GNFB, but in extremely low numbers, such as 12-17 dB typically. And they do sound a little different from their competitors, I believe because of this, since they advocate a very wide opan loop bandwidth, typically out to 80 kHz and above. Examples would be HK 680 integrated amp (from 1999) and Citation 24 (from 1998, I think), both using just 12 dB (3:1) of GNFB.
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Are you sure, Jacco?
Its production started in 1987, perhaps, but as far as I am aware, it went on for several years - I don't know how long.
May I enquire as to your source, meaning a link, perhaps? I could be wrong, and I'd like to learn more about it.
As for the HK 680, I know for a fact that it was withdrawn from the Germaqn market, from which my sample was brought in 1998, I distinctly remember buying it in September, and it was withdrawn a few months before that.
Its production started in 1987, perhaps, but as far as I am aware, it went on for several years - I don't know how long.
May I enquire as to your source, meaning a link, perhaps? I could be wrong, and I'd like to learn more about it.
As for the HK 680, I know for a fact that it was withdrawn from the Germaqn market, from which my sample was brought in 1998, I distinctly remember buying it in September, and it was withdrawn a few months before that.
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Memory, my head came with a hard drive manufactured by Bean-Counter corp.
In general, mentioning the year of a product refers to the moment in time it was released.
(don't quite understand why anyone would wish to know the date someone bought something)
Citation 24 Power Amplifier by Harman Kardon Valuation Report by UsedPrice.com
Citation 22+24 users manual came out in '87, see last page : http://www.harmankardon.com/resourc...ments/en-US/OwnersManual/Citation22-24 om.pdf
(Marantz manufactured the 24 for Harman, which was also part of the reason why the model was discontinued in 1989)
Bipolars in one of our foundry processes have Ft NPN 50GHz and PNP 35GHz . Would that be fast enough for the next generation of audio electronics, or do we need to wait for Ft's in the 100's of GHz?
we are a little short of complementary power output devices at the next step up in frequency - that requires packaging changes for the RF parasitics
but linear RF N Mosfet packaged to push loop speed up over an order of magnitude from todays low single digit MHz gain intercept have been available for more than a decade - haven't heard of any designing audio amps with them though
DE Series MOSFETs
but linear RF N Mosfet packaged to push loop speed up over an order of magnitude from todays low single digit MHz gain intercept have been available for more than a decade - haven't heard of any designing audio amps with them though
DE Series MOSFETs
Thank you anyway, Jacco.
I asked about the end date of manufacturing because a few, although rare, surprises are possible. For example, my Luxman C-03 was originally released in 1987, but was discontinued in 1994 or a bit later. It turned out to be an absolute bestseller, Luxman's best ever product in terms of longevity, and I've seen an estimate that it's the No.1 best selling preampa of all time.
Some actually stamp their products inside - my Marantz 170 DC was made on 27 March 1978, according to their time stamp. Hardly important, but nevertheless nice to know.
Consumer audio is similar to the automobile industry, a new model is required every couple of years to keep sales figures up.
Audio shows were annual or biennially events in the '70s and '80s, consumer grade manufacturers couldn't afford to have the production life of a model span across more than two, or three shows at the utmost.
As with cars, audio manufacturers nowadays stretch the life time of production series by minor updates in the shape of a MKII refresher (or KI amusement), before releasing a totally new development.
The C-03/M-03 pre- and power amp duo were kept on active sale long after manufacture had ended, simply made too many of them and were left with a huge stock. Here, either of the two could be bought new with official guarantee for half retail.
One way of getting a medal, like good ol' Lance.
(I fancied the C-05/M-05 combo more, or e.g. the Onkyo M-510, in active production for close to a decade)
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The objective people on this forum also listen, it is just that they back up their listening experience with measurements' and science, it is the "listen only" crowd who tend to believe in magic that always shoot the objective people down for doing things properly.
As to war there is no war, just debate....
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