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Class D Switching Power Amplifiers and Power D/A conversion

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Old 3rd March 2013, 06:47 PM   #41
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Accuphase E202... wasn't this the exotic type with adjustable output impedance / damping factor?
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Old 9th August 2013, 11:55 PM   #42
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Originally Posted by theAnonymous1 View Post
I don't know what defines "air", but I've never found Class-D lacking.
I have an old audio book, The Gramophone Handbook, by Percy Wilson, published in 1957. Wilson was an elderly man when he wrote the book and his involvement in reproduced music went way back.
He mentions that back in the late 20's when when both electrical recording and gramophones were first introduced many enthusiasts steadfastly, and loudly, refused to contemplate the new system. How could an electrical system of recording and reproduction possibly be better than their beloved 'acoustical' method of sound box, tone arm and horns?
Some folk do not like change!
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Old 17th August 2013, 04:06 PM   #43
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I have a UCD700HG amp with HG power supply. Initially I thought it sounded great. Lot's of control, mature sound with vice grip. Can go loud without a strain. After comparing it to my almost 20 year old Hiraga Le classe A 20W amp I had serious second thoughts. The Hiraga has lots and lots more decay on every note it plays. There is a lot more low level information at the end of each note while the UCD amp seem to cut off before the note ends. This is what makes the sound much more "airy" and much more enjoyable to listen to. I also have a pair of Trends TA10 amps wich are pretty terrible in this department at a point that they are almost unlistenable for me. I have heard other Tripath amps do the same things so I gave up on Tripath in general. The UCD700 is moved to the woofers in my active system where it does a pretty good job. My old NAD2200PE wich I used before on the woofers had more slam than the UCD's but the UCD's just never run out of steam and while more polite it integrates better in the system.
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Old 17th August 2013, 04:55 PM   #44
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Originally Posted by Sjef View Post
I have a UCD700HG amp with HG power supply. Initially I thought it sounded great. Lot's of control, mature sound with vice grip. Can go loud without a strain. After comparing it to my almost 20 year old Hiraga Le classe A 20W amp I had serious second thoughts. The Hiraga has lots and lots more decay on every note it plays. There is a lot more low level information at the end of each note while the UCD amp seem to cut off before the note ends. .
Comparing a 700W D amp with an 20W A amp is apples and banana. Like comparing a vintage sports car with a family van. UCD 700 would drive a PA top speaker quite efficiently while a class A amp is always nice and handy when it comes to heating your home during wintertime. Completely different application. I don t believe that the UCD does cut off notes. UCD maybe has slightly higher noise level so the note reaches "footroom threshold" earlier, when driven at only a few watts.
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Old 17th August 2013, 05:40 PM   #45
Sjef is offline Sjef  Netherlands
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For what it's worth, the 30 watt compact stereo UCD modules and the UCD 180 ST do exactly the same thing. The UCD 700 HG sounds better overall but the truncation of the notes is exactly the same on both. It's not about 700 Watt (350 watt actually) vs 20 Watt. So yes I think it's fair to compare and it's not apples vs oranges. And I don't see why a higher powered amp should be noisier at low levels then a low powered amp. If it's good designed it's dead quiet, even at micro levels.
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Old 17th August 2013, 07:12 PM   #46
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I dont think class D can be as dead silent as a linear amp. There is lots of switching jitter and the like...
Choco - your opinion?
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Old 17th August 2013, 11:16 PM   #47
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I dont think class D can be as dead silent as a linear amp. There is lots of switching jitter and the like...
Choco - your opinion?
You can actually hear a D-amp switching? What about the 0's and 1's of digital recordings?
I can remember back in the 70's when cassette decks with all their hiss, wow and flutter was hi-fi.
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Old 17th August 2013, 11:28 PM   #48
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We have CD and DVD sound. What do you think the compression rate is on those?
So, what does it matter, most of the "Quality" or harmonics and headroom have been removed anyway!
Back in the 90's, Yamaha Electronics produced a CD player, along with Philips, that when an orchestral part of music that required more headroom was being played, the uProcessor flagged that information up and increased the analogue output by 2 or 3dB.
All gone.
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Old 17th August 2013, 11:46 PM   #49
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I have an amp made out of two bridged IRAUDAMP1 boards capable of around 400W @ 8R. It's extremely difficult to hear any noise even with my ear pressed against the tweeter.
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Old 18th August 2013, 10:31 AM   #50
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"You can actually hear a D-amp switching?"

For sure not, but there is always jittering, which gives sidebands. The sidebands then intermodulate among themselves and at -110dB there is noise in the audio band.
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