Asymmetrical waveforms !

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IslandPink
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#91 Re: Asymmetrical waveforms !

Post by IslandPink »

It's quite a dense read, isn't it ? He could have labeled the graphs clearly with the figure numbers, that would help !
I'll keep reading, but this article is mostly from 30 years ago. If this knowledge was out there then, howcome there weren't a lot of great-sounding solid state amps around say 20 years ago or 15 years ago ?
The first one that sounded convincing to me was Nick's monoblocks ( although some of the chip amps sound half-decent ) .
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#92 Re: Asymmetrical waveforms !

Post by jack »

Apparently Self is one of most highly regarded audio designers amongst professionals - he's mostly worked for companies like Cambridge and in studio desk design.

It's a dense read as it's really a technical document written by an engineer with a target audience of other engineers. He obviously has no web design skills so the formatting doesn't help the reader.

One possibility for blameless amps not being that common may be that due to their lack of "colour" or "life" they don't sound interesting, I e. by design.

What you'll hear is your signal source and output transducers plus the acoustics of the listening space, not the amplifier...
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ed
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#93 Re: Asymmetrical waveforms !

Post by ed »

IslandPink wrote: Thu Jun 02, 2022 7:34 pm It's quite a dense read, isn't it ?
totally agree fwiw. I didn't get on with it at all and gave it to Stu soon after buying it. I much prefer the Cordell.

It seems Stu has given up diy. I wonder if that has anything to do with Doug Self. snigger....
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#94 Re: Asymmetrical waveforms !

Post by Tony Moore »

IslandPink wrote: Sat May 28, 2022 8:44 pm
jack wrote: Sat May 28, 2022 6:31 pm Completely concur with James' and other comments - we are not trying to produce a "straight piece of wire with gain" - use a Doug Self "Blameless" if you want close to that.
It's the harmonics and other distortions/non-linearities that give warmth and colour. We're just trying to get warmth & colour that we like! (and maybe understand)
I don't agree with you myself and I don't think Nick would agree either.
I would say most of my system has the aim of being low distortion, and the dev. stages over the years have only brought out colour and often 'warmth' in the material, not the opposite.
I just put in some even lower distortion speaker cables and all the stuff like colour/tone, body, presence etc got better, more feelings of real stuff in the room.
The only part of my system with some distortion engineered-in is the power amp, where I find the typical SE descending distortion profile does lend some charm to vocals.

So, what's this Doug Self amp then ?
https://www.audio-talk.co.uk/phpBB3/vie ... php?t=8263

I actually think it sounds very, very nice. Still really happy with it - in Summer Mode, no point using the Class A mode as it sounds only marginally different and not worth the extra power usage and heat output.
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#95 Re: Asymmetrical waveforms !

Post by Paul Barker »

I wrote something long and complicated here that comes from another perspective but it didnt post when I had completed it. Where it took me looked like it would generate a double post so I went to “new posts” where it does not exist.

I may one day find enough ‘give a fook’ to drag it out of my sole again.

It was on the lines of Nickel and parafeed. Since as Steve S says PP transformers have an advantage, there is another format with said advantage, which may outweigh the added capacitor detraction, if there were one.
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#96 Re: Asymmetrical waveforms !

Post by IslandPink »

I think that article from Self, even thought it's says it's updated 2019, is still substantially from the early-90's. It has that 1980's-centric theme that getting very low THD on a resistive load is the be-all and end-all of good sound.
However, looking through the chapter listing of his Sixth-edition does show an encouragingly large range of topics, many of which must have been added in recent years.
I notice that the latest amps are regarded as 'Beyond blameless' which does tell a story of some sort. Maybe the amp you like, Nick, is only 'blameless' ? :)
Would be nice to hear Tony's amp some time.
I have looked at Cordell's book also, mainly the chapter/topics list, and it is similarly comprehensive - however under the Distortion chapter, there do appear to be a few critical types of distortion that are missing ( seemingly ) from Self's book.
Cordell_distortion.JPG
Cordell_distortion.JPG (33.6 KiB) Viewed 3093 times
Of the people I've read, from the solid-state side ( few ! ) , the one that makes most sense and interests me most is John Curl. I read very many pages from his massive 'Blowtorch' thread a while back, and found his comments very clear and thought-provoking. I see that there are some references to Curl, in Cordell's book.

Now I've found out that John Curl does have snippets of interviews on Youtube - so that's what I'll be doing tonight, after catching up with the latest TT practice !
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#97 Re: Asymmetrical waveforms !

Post by IslandPink »

jack wrote: Thu Jun 02, 2022 2:17 pm I assume that this is a wind-up
No, it wasn't ( thanks )
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#98 Re: Asymmetrical waveforms !

Post by JamesD »

I have to say that I found the 'blameless' amp a little sterile and un-involving when I built one back in the day. I was also surprised to see him claiming it as such when Japanese super amps of the same era match his distortion specs with more power and certainly were not regarded as blameless.... e.g. Technics SE-A5000 thd 0.0007% at 160W into 8 ohms per channel and that isn't their top of the range amp - I just happen to have the specs to hand...

It was trying amps such as the blameless amp that turned me back to valve amplifiers... and whilst valve amps they are generally better at reproducing musical performances - they are not perfect either...
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#99 Re: Asymmetrical waveforms !

Post by Nick »

I just happen to have the specs to hand
What might be more interesting is one of the amps and actually measuring it. It comes to mind that in the days when the Japanese were reporting 0.0007% there were not that many bits of kit that could measure that.
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#100 Re: Asymmetrical waveforms !

Post by JamesD »

Nick,

Doug Self was publishing graphs of his amp producing this... we're talking about 1990s here after all - The Technics amp being in production from 1991 to 1994. Its a pretty amp: http://www.thevintageknob.org/technics-SE-A5000.html

Actually you have a point as the AP System 1 (1985) accuracy was 0.0010% so Technics claim to beat that as does Doug Self... interesting - its possible with a better sig gen as the AP limit is its internal sig gen of the test signal- the measuring side does better so if they had a better generator they might have made it possible...

I would love to have one to measure and listen too - particularly through something like Yamaha NSX-10000...

BTW - I wasn't saying the blameless amp sounded poor or like as japanese ss amp at all but it didn't do what I was looking for... and the valve amplifiers I had like a Rogers Cadet and Leak TL-12s got closer to what I wanted...

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#101 Re: Asymmetrical waveforms !

Post by Nick »

Doug Self was publishing graphs of his amp
Yes, I know, it was the claims that the Japanese were making that I was questioning. Which I suspect were responsible for a generation believing that measurements were not to be trusted. After all if it measured like that and still didn't sound that good, its clear that we cant trust measurements, or at least there is no correlation between measurements and sound. Personally I don't trust the marketing that produced the numbers for the Japanese amps.

I could be wrong.
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#102 Re: Asymmetrical waveforms !

Post by Nick »

Also, this is a useful little thing.

http://www.cordellaudio.com/instrumenta ... fier.shtml
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#103 Re: Asymmetrical waveforms !

Post by steve s »

Nick wrote: Fri Jun 03, 2022 10:46 pm After all if it measured like that and still didn't sound that good, its clear that we cant trust measurements, or at least there is no correlation between measurements and sound

I think many of us would be in full agreement with that nick, ( hopefully I've quoted in the right context)

I suppose the question on my mind is why, despite the 'perfect' measurements
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#104 Re: Asymmetrical waveforms !

Post by izzy wizzy »

steve s wrote: Sat Jun 04, 2022 12:21 am I suppose the question on my mind is why, despite the 'perfect' measurements
I think it's like the issues F1 cars have. Despite the "perfect" measurements in their static testing and wind tunnel, the car on the track can do something completely different under dynamic conditions. Witness Mercedes and their porpoising issues.

Most tests, the majority of conventional ones I've seen on amplifiers use perfect loads and realitively (to music) static conditions.

Either bandwidth measurements at high or low level but not both. Intermod using two frequencies where IRL there's loads, resistive loads where nothing like that exists IRL. Kinda like testing a car on a rolling road. It's nothing like real life.

They are relevant to some degree as it's a measure of does it work OK.
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#105 Re: Asymmetrical waveforms !

Post by Paul Barker »

I experienced the F1 Merc fail trying to implement pneumatic turntable support! Better described as wailing!
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