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Old 25th June 2012, 12:02 PM   #6401
DF96 is offline DF96  England
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Originally Posted by Pano
At some point we have to set how much ripple (or other faults) is acceptable to us, or to those who buy amplifiers.
The former is psychoacoustics, the latter mainly marketing. It is, of course, conceivable that some people prefer their sound to be accompanied by some low level hum or close-in IM products. As for distortion, it may be that the curve does not always go through the origin.

For those who demand 'stored energy to cope with transients', I think we can agree that a ripple calculation captures the essential elements. The snag is that we don't know what x% should be. The worst-case 'transient' for this issue is not HF or low LF but signals at or near line frequency: 50/60Hz. If more capacitance gives an impression of more deep bass then this either means the amp has poor PSRR (and not enough feedback?) or our brain is doing sub-harmonic synthesis.
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Old 25th June 2012, 12:03 PM   #6402
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Originally Posted by jacco vermeulen View Post
Interesting (to me) still are the geographic preferences ;
High VA/W numbers in the US, with a relatively large uF bank, e.g. Parasound amp models.
UK designers who favor soft powersupplies, relatively low size capacitors (and Nigel is unmistakenly British ).
Powersupplies as rigid as a tank, with steep electrolytic size, in the Germanic region.
Thanks Jacco, that's an interesting view of it. Might have something to do with the styles of speakers and the size of the listening rooms.

A few years back there was a lot of debate on the Class-D forum about how much cap is enough. Some liked the sound of massive capacitance, some wanted barely any at all - and just about no one would budge on what they liked. I began to wonder if it had to do with damping factor and the speakers being used.
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Old 25th June 2012, 12:29 PM   #6403
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Originally Posted by Pano View Post
Might have something to do with
Goes way beyond that, imo.

Look around you.
Mr Wayne can only be American, Mr Veselinovic's amp flavor is rooted in the moderately liberal days of pre-1989.
(and Mr Yaniger, eeh....let's skip Mr Yaniger)

What would you have favored/listened to, if they hadn't fckd up your mind in France ?
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Old 25th June 2012, 01:11 PM   #6404
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Like most standards, it's a Procrustean bed. Unfortunately, real world source material is not made to DIN standards, and the increased use of compression has made things worse. THD is far less relevant than recovery from overload (e.g., blocking in cap coupled amps, "sticking" to rails in DC amps) and modulation of the signal from the increased ripple components and sag from the power supply.
Where were you when they made them happen, way back in 1971?

At the time, there were prescious few of any standards, anywhere. IHF was also in the making, and the Japanese standards were still a far off dream ...

After the battle, everybody's a general.
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Old 25th June 2012, 03:01 PM   #6405
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Originally Posted by jacco vermeulen View Post
Berendsen in Germany still offers a 150W stereo power amp type in two versions ; a regular with 60.000uF and a Special Edition with 100.000uF capacitance.
Back in the late '80s, early '90s, i audited their monaural Blue and Red editions on different loudspeakers.
Red or Blue was not distinguishable on an easy loudspeaker, the trickier loudspeaker model favored the pumped up Red brigade.
I told you, the red one is better ...
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Old 25th June 2012, 03:12 PM   #6406
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Originally Posted by Pano View Post
Thanks Jacco, that's an interesting view of it. Might have something to do with the styles of speakers and the size of the listening rooms.

A few years back there was a lot of debate on the Class-D forum about how much cap is enough. Some liked the sound of massive capacitance, some wanted barely any at all - and just about no one would budge on what they liked. I began to wonder if it had to do with damping factor and the speakers being used.
Someone said about shunt PSU's shunting all and everything . I had never thought about back EMF . Perhaps Shunt and class D makes sense if I understood correctly about shunt damping chokes etc . The problem with D is " Bus pumping " this is where energy fly's back into the PSU during switching . Arranging the transistors in an H Bridge helps . However the dead period still makes for nasty pulses . I think I am right in saying Hypex is not an H bridge . It almost looks class B in layout .

My instinct is that the class D users will not use a shunt PSU . It's the fact that the postage stamp produces 100 W that is the big deal .

I also think class H ( G ) far better . Not least if the bottom half is class A . If 10 watts it doesn't need to use much current . It can be what ever you like above that .

I am listening to a 8 watt class A amp right now at about 1 watt . I have just been told it is too loud . The speakers are 87dB efficiency .

BTW . The power supply is 500 V and 330 uF after that a 10 uF multiplier using NFET . It looses 8V . It is silent . The sound as Mr Wayne said is the same when I pull the plug for a few seconds . Valves are fun .
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Old 25th June 2012, 03:16 PM   #6407
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Well, then, we're agreeing. There is no "rule," you have to actually engineer competently to get a desired performance.
Nice to see you coming around, but there are rules! It is just the more experienced know when to break the rules!

The joke in racing is the guy who wins is the one who knows the rules the best. They can "cheat" by avoiding the intent of the rules and get more oomph while still staying within the written rules!
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Old 25th June 2012, 03:19 PM   #6408
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Haven't you been involved with class D works, Mr Pearson ?
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Old 25th June 2012, 03:50 PM   #6409
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Originally Posted by Pano View Post
Thanks Jacco, that's an interesting view of it. Might have something to do with the styles of speakers and the size of the listening rooms.

A few years back there was a lot of debate on the Class-D forum about how much cap is enough. Some liked the sound of massive capacitance, some wanted barely any at all - and just about no one would budge on what they liked. I began to wonder if it had to do with damping factor and the speakers being used.
It may be correlated, since damping factor depends on amount of feedback. Feedback reduces dependence of amplification factor on powering voltage allowing deeper ripples per the same dirt.
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Old 25th June 2012, 04:28 PM   #6410
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Thanks Jacco, that's an interesting view of it. Might have something to do with the styles of speakers and the size of the listening rooms.

A few years back there was a lot of debate on the Class-D forum about how much cap is enough. Some liked the sound of massive capacitance, some wanted barely any at all - and just about no one would budge on what they liked. I began to wonder if it had to do with damping factor and the speakers being used.
Well, most German speakers have been rated for nominally 4 Ohms, this causing them to use adjusted for the load power supplies. Even the old DIN 45500 audio related standards took 4 Ohms as their reference value.

And, despite much lower power levels available into 8 Ohms, by and large German mainstream products did tend to sound better than their nominally more powerful Japanese counterparts. For example, a Grundig amp or receiver with about 30-40 WPC into 8 Ohms almost by default sounded better and more convincing than a typical whizz bang Japanese mainstream product, with lots of "features", sexy FET inputs and whatnot, while that Grundig had to make do with simple BC series transistors.

I won't even mention some of Philips' offerings, or their range topping Black Tulip products, which were way out in terms of sound - their only failing, which turned out to be critical, was that they were from Philips, usually associated with toasters and electric shavers, with a marketing department incapable of giving it away, let alone selling it. A great pity. As a matter of fact, I think Philips has always been downplayed way over what was reasonable regarding sound, those men know more about sound than many a famous "High End" name.
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