2. amps-preamps
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Will new Class D trump a vintage Class A/AB?

After 6 years on a shelf, I finally got a 1986 VSP Labs TransMOS 150 power amp fixed. Back in its heydey, the Gold Edition of this amp was one of J. Gordon Holt's favorite amps for neturality and musicality. It's fairly heavily biased into Class A, as the VSPs run on the warm side. They weigh a ton--50-60 lbs depending on whether you have the 150wpc or 200wpc version. They are stable all the way down to 0 ohms, have a really high damping factor, and have deep, extended, tightly controlled bass. It's one of the first MOSFET transconductance amps--it's a solid state implementation of tube amp topology. I remember it being fairly fast, but especially liquid.

Now, I haven't heard a VSP in years (even though I have 4 of 'em--most needed recaps or something).

Anyway, in a fit of impulse-buying, I ordered an Onkyo A-9555 class D integrated amp, which has been enthusiastically reviewed and recommended by both Absolute Sound and Stereophile.

So whaddaya all think? Has amplifier development come far enough in the past 22 years that a high quality MIJ class D integrated could give a handmade boutique old school AB amp from the '80s a run for the money? I know I'll find out in a couple of weeks, but which way do you think it'll go?
johnnyb53
johnnyb53 OP
3,510 posts
 
Well, my old VSP Labs TransMOS didn't get off to a good start. After getting it out of repair yesterday (they replaced some capacitors and (looks like) a relay or two) and $143 later, I took it home and hooked it up. It's putting out a really loud hum, and unlike another VSP I have, adding the 2-prong cheater plug didn't help. When I say "loud hum," I mean it's as loud or louder than the music I was going to listen to. It's not something upstream, because when I put my similarly aged-and-wheezy Amber Series 70 back in the chain, everything was fine.

So Monday I'll be calling the repair shop to have them track that down. I don't think it hummed the last time I'd used it. It just had this pesky habit of letting AC spikes through the amp and killing the tweeters.

Just on the dodginess-of-vintage-gear issue, I'm looking forward to seeing what the Onkyo can do. If it works as I hope it will, I will be dumping 6 old amps and 2 more preamps at a used hi-fi store. One good new piece of gear can clear out a lot of marginally performing accumulation.

That was what I was hoping for when I tried out an Outlaw RR150 a couple years ago. But no way could it compete with the Amber, and my stacks of dodgy old gear stayed in the garage as backup to the Amber stack.
johnnyb53 OP
3,510 posts
 
08-23-08: Dotsystem
Few amps can handle zero ohm territory. The class D implementation distortion signature may or may not be to your liking. Many class D amps come in small chassis and have a switching power supply built in to the amp module. Big chassis class D like the H20 have linear power supplies.
Onkyo apparently took a couple of pages out of PS Audio's book; 1) They use a much larger power supply than is typical of compact class D designs. The 85 wpc Onkyo weighs nearly 28 lbs. 2) They also use a variable gain stage in the preamp rather than a constant gain that is attenuated by the vol. control.
mapman's avatar
mapman
22,464 posts
 
I've heard good things about the Onkyo. Should be interesting.
dcstep
1,518 posts
 
Hmm, why didn't you stay with boutique? The very best in Class D is from the boutique makers, like Rowland and Spectral.

Get the Rowland Continuum 500 and your days of tracking down hum will be over. Also, you'll be able to sit back and play music.

Dave
johnnyb53 OP
3,510 posts
 
08-23-08: Dcstep
Hmm, why didn't you stay with boutique? The very best in Class D is from the boutique makers, like Rowland and Spectral.
Because I'm a cheap bottom-feeder. :) Actually, I had to quit working a couple years ago due to health reasons, so I try to satisfy my audiophile ears by buying legendary gear on the used market, closeouts, and supplement it by selling the gear I'm replacing.
Get the Rowland Continuum 500 and your days of tracking down hum will be over. Also, you'll be able to sit back and play music.
Good advice if I wanted to dip into my home equity. But for now I'm going to give this Onkyo a try. Word is that this unit is freaky-quiet. I think the Stereophile reviewer uses really sensitive Avant Garde Duos or Trios that reveal any electronic noise in the system, and the A-9555 made no noise at all.

The other thing that owners and pro reviewers consistently say of the Onkyo is that you have to spend *a lot* more (like 4x the list price) to get a significant improvement.

Here's hopin'.
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