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Old 2nd May 2019, 3:17 pm   #61
Radio Wrangler
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Default Re: So what's the deal with single ended hifi amps?

Ooooh

It's got 'Dignity'

Can I claim first sighting of a new parameter?

David
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Old 2nd May 2019, 3:42 pm   #62
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Default Re: So what's the deal with single ended hifi amps?

Quote:
Originally Posted by Studio263 View Post
Quote:
Originally Posted by Synchrodyne View Post
Single-ended transistor amplifiers are a rare species.
Hardly! Every early Sony Trinitron colour TV had one up to the mid 70s and they were not alone; Hitachi used this topology too, as did many other Japanese manufacturers. BRC also used this method for the very popular for their 8000 series sets. That lot alone encompasses millions of individual pieces of equipment.

In an early transistorised colour TV set there was usually a DC supply of around 115V which was stable, so long as you didn't take random gulps of current out of it. A transformer coupled singled ended audio output stage was therefore ideal for the 1 > 2W of audio output that was expected.
Yes, it works just fine! Motorola did a series of high-voltage plastic transistors [MJE340/MJE360] specifically for this sort of application.
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Old 2nd May 2019, 4:11 pm   #63
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Default Re: So what's the deal with single ended hifi amps?

One of Motorola's marketing circulars featured MJE340, the claim was that their single ended circuit used fewer components and was compatible with set designs having a high supply voltage. I think it was around the time hybrid tellies were definitely on the way out.

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Old 2nd May 2019, 4:21 pm   #64
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Default Re: So what's the deal with single ended hifi amps?

The TV single-ended audio output circuits were more a case of by-the-farthing minimalism than hi-fi though- in an application that had always been the if-we-have-to poor relation of the picture bit.
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Old 2nd May 2019, 6:28 pm   #65
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Default Re: So what's the deal with single ended hifi amps?

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One thing that puzzles me is why none of the hi-fi types have ever used the idea of 'sliding bias' to get the most out of their expensive valves. At low audio-level wind the -ve grid-bias up so the valve is passing just-enough current. Then when you want more loudness, reduce the grid-bias so the anode-current rises in order to deliver the greater output.
Some them actually do the opposite of this. They bias the output with a bypassed CCS in the cathode circuit, which stabilises the wrong current: average current instead of quiescent current. As second-order distortion grows at higher outputs, the valve gets biased back. I point out to them that a simple bypassed cathode resistor would do a better job.
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Old 2nd May 2019, 6:55 pm   #66
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Default Re: So what's the deal with single ended hifi amps?

A CCS in a cathode would have to be decoupled, otherwise, if it worked, it would cancel the signal and the anode current would be constant, too.

A CCS in a diff pair phase splitter is a different matter, but surely real high-end people don't allow semiconductors in their amplifiers?

Stabilising the quiescent current of a class-B or AB stage is quite difficult. The current would have to be sampled at a time when it really is quiescent and not driving signal and not cut-off, then the determined bias voltage needs to be saved stably until the system next gets a shot at sampling the quiescent. This is a big issue in RF power amplifiers - modern RF power MOSFETs have a significant variation in threshold voltage from individual to individual and there is pressure to create designs which do not need bias adjustments... and there is pressure to not waste power.

All this is likely to blow the minds of people frightened of feedback systems.

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Old 2nd May 2019, 7:44 pm   #67
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Default Re: So what's the deal with single ended hifi amps?

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Meawhile, the Audio Note Kagura https://www.audionote.co.jp/en/produ.../kagura-i.html

Which will set you back £150k.

Craig
That would be hard to justify.

Ignoring the audiophoolery with terms like "elastic & coordinated sound", at least there are some redeeming features. For the most part, the Japanese tend to make electronic components that are just that amount better. They pay attention to detail in their designs and their precision engineering is generally excellent.

Those chassis weigh in at 62kg it says. So you really cannot fault the build quality and component quality and finish and that is always a very good thing. Whether that stacks up with the price is debatable, but a good job on the construction and components is always very nice to see.

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Old 2nd May 2019, 9:07 pm   #68
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Default Re: So what's the deal with single ended hifi amps?

Bulls**t in Japlish. What more could anyone want?
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Old 2nd May 2019, 9:23 pm   #69
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Default Re: So what's the deal with single ended hifi amps?

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Stabilising the quiescent current of a class-B or AB stage is quite difficult. The current would have to be sampled at a time when it really is quiescent and not driving signal and not cut-off, then the determined bias voltage needs to be saved stably until the system next gets a shot at sampling the quiescent.
Someone did do a circuit and PCB to do this properly but it is not as well known as it should be. I think it took a sample on zero crossings.
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Old 2nd May 2019, 9:23 pm   #70
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Default Re: So what's the deal with single ended hifi amps?

Whoa! I should've hung on to my parallel SE Grampian PA amp with its pair of EL41s. Might have been worth big bucks!
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Old 2nd May 2019, 9:51 pm   #71
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Default Re: So what's the deal with single ended hifi amps?

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Meawhile, the Audio Note Kagura https://www.audionote.co.jp/en/produ.../kagura-i.html

Which will set you back £150k.
Those chassis weigh in at 62kg it says. So you really cannot fault the build quality and component quality and finish and that is always a very good thing. Whether that stacks up with the price is debatable, but a good job on the construction and components is always very nice to see.
Hmmm. Agree with Argus, the build quality does look good. However, even as a one-off, I reckon I could build one for £15,000 rather than £150,000. Silver wire in the output transformers (10% better conductivity than copper) isn't going to cost more than a couple of grand. Cut-cores are easily available. I'd actually have one thumping big transformer rather than three separate mains transformers for heaters, rectifier heater, and HT. And I'm not sure where I'd get 'oscillation-proof' capacitors.
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Old 2nd May 2019, 10:30 pm   #72
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Default Re: So what's the deal with single ended hifi amps?

I dont think you could buy the linear crystal oxygen free silver wire that they use Kalee. It was the Ongaku amp that was the basis for the whopping big SE 211/VT4C amp that I made for somebody. I used enameled copper wire though, because I couldnt find the wire either.

Nobody has yet mentioned to 50 grand single 4" driver speakers with 5 metre long horns attached to make them work properly, nor the 0 B&S speaker wire required.

Joe
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Old 2nd May 2019, 10:31 pm   #73
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Default Re: So what's the deal with single ended hifi amps?

Quote:
Originally Posted by Studio263 View Post
Quote:
Originally Posted by Synchrodyne View Post
Single-ended transistor amplifiers are a rare species.
Hardly! Every early Sony Trinitron colour TV had one up to the mid 70s and they were not alone; Hitachi used this topology too, as did many other Japanese manufacturers. BRC also used this method for the very popular for their 8000 series sets. That lot alone encompasses millions of individual pieces of equipment.

In an early transistorised colour TV set there was usually a DC supply of around 115V which was stable, so long as you didn't take random gulps of current out of it. A transformer coupled singled ended audio output stage was therefore ideal for the 1 > 2W of audio output that was expected.
Thanks for that. I had clean forgotten about the TV sound case.

Now that I have been reminded, I should note that that the single-ended Class A transistor output might also have been significant in American TV practice of the late 1960s. One of RCA’s second generation intercarrier/AF ICs, the CA3042, was specifically designed to directly drive an NPN transistor (or a high-gain pentode) output stage. (Its CA3041 companion was designed to drive a beam tetrode.)

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Not only that, but the 1967 TI circuits book devoted a whole chapter to Class A, single transistor output stages.


Cheers,
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Old 2nd May 2019, 11:39 pm   #74
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Default Re: So what's the deal with single ended hifi amps?

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Hmmm. Agree with Argus, the build quality does look good. However, even as a one-off, I reckon I could build one for £15,000 rather than £150,000. Silver wire in the output transformers (10% better conductivity than copper) isn't going to cost more than a couple of grand. Cut-cores are easily available. I'd actually have one thumping big transformer rather than three separate mains transformers for heaters, rectifier heater, and HT. And I'm not sure where I'd get 'oscillation-proof' capacitors.
There are actually two Audio Note's. The original Japanese one that makes the esoteric, supercar priced and yes - beautiful and well built gear. And Audio Note UK, run by Peter Qvortrup. Who also build esoteric valved gear, but have hardly anything in common with Audio Note Japan.

The only nod to AN/Japan is the Ongaku https://www.audionote.co.uk/ongaku-kensei which is eye-wateringly expensive at £95k. It has been in continuous manufacture in Japan for getting on 30 years.
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Old 3rd May 2019, 2:31 am   #75
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Default Re: So what's the deal with single ended hifi amps?

People don't bat an eye at those sorts of prices for jewellery, and jewellery doesn't even pretend to have any purpose beyond showing off, though it might be a hedge against inflation.

Those prices will only buy you an entry level supercar. Supercars are spectacularly useless at performing transportation and Lamborghinis seem to like catching fire and getting you laughed at on youtube. Again, tools for showing off with. Unlike hifi, the showmanship is in public. Just carry a big extinguisher and avoid speed bumped roads... Oh, there isn't any luggage space to put that extinguisher? Hire a minion with a big extinguisher in a cheap car to follow you around!

Those prices will get you a superwatch. A show-off's wristwatch that functions little better than a fiver will buy you at a petrol station. You might see a difference if you took it diving.

Perhaps with the overpriced hifi we are the ones not understanding it? Maybe we are mistaken in judging it in terms of reproduction of sound, its real purpose lies in the bragging rights and the showcasing of wealth? The claims of superior reproduction which only the chosen few can hear are a cover story designed to enhance the exclusivity? We are not the target market, we don't even understand the interests of the target market.

I have, at least, finally figured out just what the purpose of a Kardashian is... It is to stop magazines having empty pages. When I first heard of them, I thought they were bad guys in Star Trek.

This high-end stuff is a small echo in our universe of the goings on in an orthoganal universe where wealth and irrational spending are the norm.

Don't try to apply logic and rationality, just sit back and enjoy the show. Have a chuckle at the deflagrating supercars and the lasses staggering around in heel-less footwear - their menfolk will doubtless be compelled to wear them in a season or two's time...

It's all a show.

The buyers of this stuff wouldn't bother if they didn't think they had an audience.

David
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Old 3rd May 2019, 8:08 am   #76
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Default Re: So what's the deal with single ended hifi amps?

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This high-end stuff is a small echo in our universe of the goings on in an orthoganal universe where wealth and irrational spending are the norm.
Still, I think in the case of those Japanese amplifiers, there is nothing wrong with the amplifiers themselves. They are made to a very high standard and regardless of price, that is admirable. Our world is now full of so much "short term plastic rubbish" I can't help admire what the Japanese engineers did there.

Then, there is the issue of price, marketing (perception management) and perceived value.

It is almost ironic that a beautifully made piece of electronic apparatus cannot speak for itself. If could, perhaps, if the average customer had knowledge of the topic.

So when the "marketing engineers" got hold of a beautifully made piece of equipment they think, how can we persuade people its 10 times better than what it is (not that it is even possible) and charge 10 times the price.

I think those amps are worth about $15k to $30k, not $150k.

If they were properly priced I would buy one myself because I admire the effort and appreciate the finish (exclusive of any audio performance), because I like it when somebody goes the extra mile to marry science and art and believes in making something that not only works very well, but is beautiful too.

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Old 3rd May 2019, 9:19 am   #77
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Default Re: So what's the deal with single ended hifi amps?

It is interesting that the sound quality of the AN Japan is lauded - and testimony to that is the 30 year product lifetime of the Ongaku. However the harmonic distortion is exceptionally high - AN's own performance figure is at 27W (Ongaku) and 50W (Kagura) and 5% distortion at 1kHz.

On the other hand, harmonic distortion in moving coil loudspeakers is of that order, and vinyl with a pivoted arm (ie not parallel tracking) is around 1%. And we cheerfully gloss over that - and those distortion mechanisms are present regardless of how much you pay for the product.

Yet other than single ended valved amps, any other amp that gives harmonic distortion greater than a few parts per million runs the risk of getting panned. For example https://www.neurochrome.com/tortuga-audio-ldr3/ . The guy does not seem to have actually listened to the thing - reminiscent of the 1970's audio press (HiFi News) which published measurements and did no listening at all.

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Old 3rd May 2019, 10:20 am   #78
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Default Re: So what's the deal with single ended hifi amps?

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It is interesting that the sound quality of the AN Japan is lauded - and testimony to that is the 30 year product lifetime of the Ongaku. However the harmonic distortion is exceptionally high - AN's own performance figure is at 27W (Ongaku) and 50W (Kagura) and 5% distortion at 1kHz.
I'd much rather have a well constructed amplifier with 5% distortion than a poorly made one with 0.001% distortion. I know I cannot hear the difference, I might just perceive it, if it got to 8 or 10% and I was trying hard on a listening test with some ideal test signal.
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Old 3rd May 2019, 10:46 am   #79
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Default Re: So what's the deal with single ended hifi amps?

Accepted
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Old 3rd May 2019, 11:26 am   #80
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Default Re: So what's the deal with single ended hifi amps?

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So when the "marketing engineers" got hold of a beautifully made piece of equipment they think, how can we persuade people its 10 times better than what it is (not that it is even possible) and charge 10 times the price.
Charging 10 times the price is the main means of justifying charging 10 times the price. Nobody would believe you if you said it was worth 10 times but only charged 5 times.
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