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Class D Switching Power Amplifiers and Power D/A conversion

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Old 13th January 2010, 04:49 PM   #31
Ltralus is offline Ltralus  Denmark
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That a potentially destructive test was voluntarily carried out on your own amps, as you stood there watching, further brings into question your own motivation and affiliations. Don't pass the buck by saying "he", italicized no less, nameless expert, did it. Hobbyists do not look for problems that they aren't experiencing, so what was your personal motivation in that test? If he were so expert he'd never have driven the input with such a signal in the first place, and I would very much like to see such a bogus test repeated with an amp of any other class to see what happens to your output and zobel alike. Try it, I dare you, and watch how fast it smokes. I am suggesting zobels as typically designed will blow apart when driven with an improper signal as you have done here.

Now your issue is not what might happen in the presence of an absurd signal; nothing it seems, but that the "iron"-- nameless expert technician term, filters too poorly. Is that all the time or some of the time or only in the presence of an absurd signal?

The word oscillation is apt in proper context and I found that wasn't how you used it, intentionally or not. That you'd defend your improper use that twisted the context for added shock and fear value, even after having been informed, is illuminating. Coupled with "other problem amps" implies something on your part, like ("but class d") is problem by design, which is true and that's what makes a good one so difficult.

Saying you like it for bi-amping is just repeating the common two decade old "they're only good for bass reproduction" in so many words. That's a false compliment like "expert technician" which is something of an oxymoron in itself, but according to you, you're above all these tactics, right. Even though your final statement was exactly what you said it isn't, but truth seems to be a problem here.

I mean, that's a whole lot of what ifs and pseudo expert, pseudo third party, pseudo conclusions, simply to state your preference, isn't it. Matter of fact the preference you stated wasn't so much "class A", but class A "like this one", which happens to also be an Aussie company, like where you and your expert friend are from.

You can add a zobel if you like, btw, but don't pretend there's some sort of instability issue that it has to tame in this amplifier.

You are free to express an opinion and others are free to call you on your obvious "errors", many of which went well and far beyond what one would consider an "opinion". What's the point in whining about a two way street if only have to have the moderators debate me where you failed to. Surely that's another tactic you're above.
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Old 13th January 2010, 05:02 PM   #32
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Please keep the discussion factual and on topic. Any more personal attacks will result in bin time!
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Old 13th January 2010, 08:05 PM   #33
JE is offline JE  Netherlands
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I have the tentlabs DIY hybrid amplifier (TentLabs). It uses the UCD400 as power stage with the OPAMP's replaced by a valve stage (double triode) with step-down signal transformers.

I have compared this amplifier with the NAIM Supernait with a supercap powersupply (over 4400 euro's). The NAIM is no match to the Tentlabs, the Tentlabs outplays the NAIM easily if you look at the amount a detail you hear in the music.

For me is this proof that the UcD400, combined with a good input stage is a top class D amplifier.
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Old 13th January 2010, 11:47 PM   #34
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I'd like to say that I have no commercial affiliations with any amplifier manufacturers, hi-fi stores or anyone in electronics. I have never heard that particular Class-A kit amp. It was chosen purely at random as a kit that may be of interest to readers of this forum becuse it is DIY. It is now available even more cheaply elsewhere online.

To have my words quoted, twisted, embellished and then analysed by an anonymous subscriber is quite to be expected, but can hardly be considered constructive.

My UcD400 modules leave a high frequency sine wave in the output. No matter what you do to the input buffer and power supply, that will always be there as it is generated onboard and downstream. If people are happy to attach tweeters with short, low capacitance cables then that's their choice.
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Old 14th January 2010, 06:16 PM   #35
Zeta4 is offline Zeta4  United Kingdom
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Ive had some commercial dealings with Class D amps so you might be interested in my
experiences.

Some years ago I was involved with the manufacture of a power amp based on the Tripath TA1040A module. While we had reliability problems with the module I dont
recall any problems with burnt tweeters. This module had from memory about 2V
of 660Khz idle noise of its o/p.

Since then I built many amps using the Hypex Ucd400 module which has been much more reliable with again no reported problems with burnt tweeters. This module also has some idle noise on its o/p

But we have had a few cases of burnouts with our ribbon supertweeter until we put in better protection. This has a flat mostly resistive impedance out to 100Khz so is more susceptable. This has happened with a wide variety of amp types not specifically Class D. We believe its due to some amps being driven into clipping.

I used to use the Ucd in my personal system quite happily until an colleague brought along a 300B DHT SE amp for me to try . Now I use the Ucd for Bass/Lower mid and the SE for the rest. Works superbly for me.
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