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Old 11th February 2012, 08:42 PM   #2201
bcarso is offline bcarso  United States
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Join Date: May 2005
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Quote:
Originally Posted by a.wayne View Post
What about Levinsons jump to Smps in there reference amplifier...?

Thoughts anyone .....
And now I see from the ad in Stereophile that arrived today, that Levinson is offering a switchmode amplifier (as well? or is that what you were referring to?).

It is almost certainly using Gerald Stanley's interleaved topology ("class I") to get its stated (equivalent) 4MHz switching frequency.
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Old 11th February 2012, 08:49 PM   #2202
a.wayne is offline a.wayne  United States
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Quote:
Originally Posted by bcarso View Post
And now I see from the ad in Stereophile that arrived today, that Levinson is offering a switchmode amplifier (as well? or is that what you were referring to?).

It is almost certainly using Gerald Stanley's interleaved topology ("class I") to get its stated (equivalent) 4MHz switching frequency.
Yes .. Sorry i meant switchmode .... saw the same ad .....
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Old 11th February 2012, 08:58 PM   #2203
Previously: Kuei Yang Wang
 
Join Date: Nov 2002
Hi,

Quote:
Originally Posted by dvv View Post
Thorsten, my onw statistical gathering research over the years indicates that the vast majority of mains noise lies between 10...80 kHz, where about 90% of it resides. These are all household appliances, computers (DAMN big polluters!), tube audio (by far the worst polluter ever, I presume due to thermal noise added to the mix, but I am not at home with tube gear!), etc, sit, and includes up to 4th harmonic.
Well, I count 30Kto 300K as I am most concerned about SMPS Noise, you call it 10KHz - 80KHz, I think we have a great deal of overlap and I do not per se disagree with the 10KHz figure...

Quote:
Originally Posted by dvv View Post
As a tube affictionado, I suppose you'll take issue with tubes, but it's really a simple test: observe the 1...100 kHz spectrum on your scope with the tube audio off and the with on. Then discuss the problem with the oscilloscope, because the S.O.B. is transistor based.
True tube gear, with tube rectifiers, choke input or filtered supplies and AC powered heaters has basically some of the lowest noise pollution fed back into the mains. I am not sure what you measured, how and with what gear, but IMNSHO it was not "Tube Power Supply" that you measured.

Quote:
Originally Posted by dvv View Post
My filter is down by 22 dB at 20 kHz, and by 80 kHz, it's down by over 46 dB, reaching a maximum attenuation rate of -72 dB at around 600 kHz. It does have a small comeback hump around 400 kHz, but it's not too bad, around 4 dB.

Oh yes, not to forget, it is an LC filter.
The above performance is specified without specifying load and source impedances. Am I to understand that your filter offers this performance regardless of source and load impedances and regardless of common mode and differential mode noise?

Quote:
Originally Posted by dvv View Post
As for the regenerators, they are just as dicey propostion. Theoretically, they should offer the best restults, but practical issues make sure that doesn't happen. In effect, they need to regenerate the sine wave, and it seems many have trouble with that, what they pass for a "sine wave" is notched blur to me; I have no idea why this is to, I never even tried analyzing one, let alone making one.
Often the reason is that they employ switched mode systems to save cost.

Implemented correctly the results of a mains regenerator can be truely astonishing. Very large Pro-Audio Amplifiers bridged may be used to provide 115V AC regenerated (one may buy them 2nd hand), very stable and low distortion sine wave generators may be build easily, giving 115V of regenerated power. The result can be WAY and I mean WAY better than any filter in measured terms.

A few killerwatt Pro Amp are surprisingly cheap these days, but it is important to make sure they use linear supplies...

Ciao T
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Old 11th February 2012, 09:14 PM   #2204
Previously: Kuei Yang Wang
 
Join Date: Nov 2002
Hi,

Quote:
Originally Posted by a.wayne View Post
These appear 3-Phase transformers?

It is hard to tell how transformers behave from the outside. There are many ways to winding them, layering, sequence of layers etc., the results differ greatly.

Ciao T
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Old 11th February 2012, 09:41 PM   #2205
tvrgeek is offline tvrgeek  United States
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Well,if I can believe anything from Spice about the DH-120, I should remove C3, the 330p dominant pole, and install 47p from base of Q6 to emitter of Q7. Conventional Miller compensation. It makes much prettier pictures. Hmmmmm, pictures good.

I also need to adjust R19 and R20 as per the app guide. 220 and 180 worked in the sim.
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Old 11th February 2012, 09:45 PM   #2206
tvrgeek is offline tvrgeek  United States
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Quote:
Originally Posted by benb View Post
Energy Star appears similar to UL certification (except of course UL is a private entity whereas Energy Star is a US Government certification) in that any product that is submitted and meets certain standards gets to use the label:
How a Product Earns the ENERGY STAR Label : ENERGY STAR
Class D Home Theater receivers would surely pass, but Class A tube amplifiers need not apply.
And I would not trust either. CSA does a lot better job.
UL is only chartered to tell you if 1: you will get fried from electricity, and 2: You will get fried when your house burns down. I don't think they do either.

Of course, as was mentioned in another thread, in the winter those wonderful Cary triodes are 100% efficient as If I could afford them, I could turn off the heat.
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Old 11th February 2012, 09:56 PM   #2207
tvrgeek is offline tvrgeek  United States
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dvv,
If you want to comment further, I would welcome it in a PM.
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Old 11th February 2012, 10:04 PM   #2208
Previously: Kuei Yang Wang
 
Join Date: Nov 2002
Hi,

Quote:
Originally Posted by tvrgeek View Post
Well,if I can believe anything from Spice about the DH-120, I should remove C3, the 330p dominant pole, and install 47p from base of Q6 to emitter of Q7. Conventional Miller compensation. It makes much prettier pictures. Hmmmmm, pictures good.
Try lead compensation instead of miller. That is cap from Vas out to negative in... May still need a touch of miller to be stable, but keep that to a minimum...

Ciao T
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Old 11th February 2012, 10:15 PM   #2209
bcarso is offline bcarso  United States
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Quote:
Originally Posted by a.wayne View Post
Yes .. Sorry i meant switchmode .... saw the same ad .....
It's probably got switchmode supplies as well. I believe, as well, Gerald likes to do some feedforward tricks with the rail voltages talking to the pulse width modulators as well, and there's probably synchronization of the PWM and the switchmode power supply. A lot going on. And the patents are still in force, available to Levinson as both Crown and ML are Harman companies.

When I first met Gerald it was just after the acquisition of Crown. I had run across a brief description in a book on power electronics of a two-quadrant switching regulator that looked a little like Gerald's patented opposed current amplifier (which lends itself readily to interleaving, and intrinsically avoids shoot-through currents of a conventional half-bridge output). When I first saw the note in the book I was thinking that it might be a way around the Crown patents. Then Crown was acquired, and as Harman was my big client I hoped that it wasn't such a way

Stanley looked at the book and seemed slightly concerned, but then noted that the pulse width modulation scheme was different. He added that when he came up with the idea, after filing on it he presented a paper to a power electronics conference and asked if anyone in the room full of people had seen anything like it (no hands were raised).

Harman is not a client anymore, but as well it turns out the two-quadrants of the example in the book were a switchmode means of sourcing and sinking current efficiently, not the bipolar voltage output that I'd hoped it might be. And once you patched the book example together with an inverted copy of itself (as it were) you got Gerald's topology
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Old 11th February 2012, 10:40 PM   #2210
Previously: Kuei Yang Wang
 
Join Date: Nov 2002
Hi,

Quote:
Originally Posted by bcarso View Post
It's probably got switchmode supplies as well. I believe, as well, Gerald likes to do some feedforward tricks with the rail voltages talking to the pulse width modulators as well, and there's probably synchronization of the PWM and the switchmode power supply. A lot going on. And the patents are still in force, available to Levinson as both Crown and ML are Harman companies.
Given the antiquity of PWM and related miscellanea I suspect that there both various ways around the patent, including money and a sufficiently motivated law-firm.

That said, while I can see many cost advantages in switched mode amplifiers, even the truly astonishing 4MHz claimed for the ML switching amp fall about 3 orders of magnitude short of what is needed for 20KHz bandwidth 16 bit audio without noise shaping...

I'd rather have 50W class AB than 500W switched mode one... The best I heard where quite wretched (as is expected, as most power amp's playing music tend to have a modulation index in the region of -20dB or more...).

I have not heard ML's version, but I have heard Crown's efforts. I'll take a DC-300 instead, thank you very much.

Ciao T
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