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
Maybe. Class D is certainly a high value option if buying new today and you have speakers with a demanding load that like to suck power and current.

Let us know what you find.
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.

If it is important to you, the class D designs should use much less electricity.
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.
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.
I've heard good things about the Onkyo. Should be interesting.
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
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'.
Understood.
mosfets rule.
No, unless you only listen to frequencies under 80hz.
Jiohnnyb53,

Whats the rest of your system that the Onkyo will be synergizing with?
08-27-08: Mapman
What's the rest of your system that the Onkyo will be synergizing with?
Source is a Technics SL1210 M5G with KAB fluid damper, Oracle Groove Isolator sorbothane mat, and Audio-Technica AT150MLX MM cart mounted on an LPGear Zupreme headshell. Although the Onkyo has a well-reviewed phono section, I plan to continue to use my outboard Cambridge Audio 640P phono stage. Most interconnects are solid core AudioQuest PSC conductors. Speakers are bi-wired Mirage OMD-15 floorstanders.

Boy I tell you, right now, the current rig using an Outlaw 950 purely for its analog line stage feeding a 22-year-old Amber Series 70 power amp is going to be hard to beat. I don't know what happened but it seems like the current system has popped into focus in the last few days.

The more I listen to this humble little Amber, the more I wonder how that amp didn't end up re-defining the state of the art for affordable 70 wpc SS amplification. Its balance of linearity, neutrality, and musicality is extraordinary. It's so good it should influence one's choice of speakers instead of the other way around. Stereophile ranked the Outlaw RR150 as a class C integrated amp/receiver, and it doesn't deserve to be mentioned in the same breath as the Amber. If a new product at $1800 came out that sounded exactly like the Amber, I wonder where S'phile would rate it.

The Onkyo is going to have to be something else to beat it.
I think the result will come down to taste and preference more than anything else.

Isn't the thing still humming though?

The Onkyo Class D was a very savvy choice for trying to improve at reasonable cost though. In that the Mirages are larger floor standers and rated 6 ohm I believe ( a somewhat more difficult than average load to drive I would suspect), I think there is a very good chance the Onkyo will work out. The main difference I would predict would be in the low end in terms of perhaps providing a fuller and tight bottom end that adds meat to the sound and helps balance things out.

LEt us know.

Cheers!
Johnnyb53 - It is difficult to compare different amps without setting price range and even then it migh be not easy. Compare 2x200W class A design to my Rowland 102 (class D) I paid $1500 for. There is no such class A amps for $1500. Class D beats many class AB designs within the same price range.

I picked Rowland since it was $100 cheaper than Bel Canto S300 and had Rowland's reputation behind (no bad product in 20 years). I don't think Onkyo was available then.

Get Continuum 500 and don't worry about home equity. One can live without a home but not without great Audio Gear.
08-27-08: Mapman
I think the result will come down to taste and preference more than anything else.

Isn't the thing still humming though?
It's the VSP Labs TransMOS 150 that hums and it's back in the shop for them to fix it right for the $144 I paid them. The Amber Series 70 currently in my analog rig does not hum. The VSP is rated at 150/300 wpc into 8/4 ohms. Rather high class A bias and very high current. Amber has a single pair of output transistors per side and is rated at 70 wpc into 8 ohms. Don't know its 4 ohm rating.

The Onkyo is similar to the Amber in power--85/170 wpc into 8/4 ohms. Rather low damping factor (25), but I wonder if that isn't just one of those bugaboos when using conventional test methods on class D amps. Plus, I don't know that the Mirage's little 5.5" woofers will need a really high damping factor.

What I'm looking to get in the Onkyo is clarity, speed, and transparency beyond what was attainable in 1986, but without sacrificing musicality, coherence, harmonic rightness.

It's scheduled for delivery Tues. Sept. 2. We shall see.
I agree about the prowess of the Amber 70. I have been using one against a worthy Muse 100 amp and the Amber has so much more character and depth- great soundstage- seemed to have trouble pushing an old Fried Beta set with Sub, but seems ok with my DQ-8's which are demanding- does well with my Spica TC-50's...always wondered what they sound like in Mono pairs-just one old review claimed they were too bright in that config..hmm, that's my 2 cents
Ostemo8's post reminded me that I hadn't updated this thread. A lot has
happened since I put my TransMos 150 back in the shop. Turns out there was
a broken ground wire inside, causing the hum.

When I got the TransMos back, it was everything I'd remembered it for
originally. It has an endearing sweetness to it, but also fullness and depth. As
good as the Amber 70 is (and they made many versions--Ostemo8's may be
a later, better edition), the VSP TransMos simply outclassed it in every way--
speed, dynamics, depth, bass clarity and extension, soundstage width, depth,
and delineation, and especially, compelling musical involvement. I can't count
the number of times it called me from other rooms to sit in the sweet spot
and listen hard and bask in its all-encompassing goodness.

BUT, I knew that 3 or 4 days after I got the VSP back I'd be taking delivery on
the Onkyo A-9555 Integrated amp.

So back to the original thread premise: Can a mass-produced Japanese class
D integrated amp trump a best-of-class high current boutique amp from the
'80s.

There are two answers: Yes, and HELL, YES!

I heard hints and even broad swaths of the greatness to come from the A-
9555 as it took its 100 hours to break in, but during that time, it had a glare
and edge that had me longing for the VSP. Still, I stuck to my guns and
played this amp in 24/7, alternating between an iPod and FM when I wasn't
spinning vinyl or 5 CDs at a time on a Sony changer.

But once I got it broken in, Hoo-BOY! This amp has introduced a new
paradigm into my home audio. It represents a quantum leap in clarity, speed,
extension, inner detail, bass clarity and detail, separation, stage width,
transient response, low level detail over the VSP, which had it over the Amber.

In fact, the Onkyo outdistances the VSP more than the VSP betters the Amber.
With about 60-70 hours on the Onkyo, I decided I needed a little respite from
the edge and glare of the break-in period. I switched the well-seasoned VSP
back into the chain, and although it was sweeter and smoother (for the time
being), I immediately noticed a big drop in resolution. At that point I couldn't
switch the Onkyo back in fast enough; I wanted to hear all that music I had
missing. At that point coincidentally the Onkyo passed its break-in threshold
and the glare disappeared, the music relaxed, and so did I. I noticed my
shoulders drop into a relaxed position and I started enjoying all the music
this amp was throwing at me.

I'm not saying the Onkyo is the equal of an Ayre or Rowland, but I will say it
reminds me more of those amps than anything else I've ever heard. It has a
lot of what is associated with a very high end amp in that it manages to be
very resolving and detailed, with an unusually low noise floor, the nuance and
subtle microdetails and smooth liquidity associated with a tube amp, along
with the fast transients, speed, clarity, bass grip, and extension at both ends
that is associated with very good solid state.

Once it breaks in, you'd never guess that it ever had a period when it
sounded edgy. It is now the most relaxed, yet properly detailed amp I've ever
had in my house. I call it "properly detailed" in the sense that it
has all that detail in correct perspective--it doesn't have exaggerated detail
or hit you over the head with it. It is quite lifelike.

I find it is as--or more--detailed than amps from Rega, Cambridge, and
Music Fidelity, and yet I prefer its musical presentation and tonal balance over
any and all of those Brit integrateds, including the 250 wpc Musical Fidelity.

As a line stage, the preamp section is easily worth the street price of the
entire amp. Unfortunately, it doesn't have line outputs, but this amp is so
good and self-sufficient I can forgive that. Like the PS Audio amps, this
Onkyo employs a variable gain stage, which keeps the clarity, transparency,
and frequency response pretty uniform at most volume settings.

The built-in phono stage is also pretty good, but the Cambridge Audio 640P
phono stage is more commensurate with the quality of the rest of the A-
9555, and is a great-sounding, sympatico match with it.

I am now done with vintage amps. As I write this I have 7 components (amps,
preamps, DAC, etc.) on consignment. I'm done with them (though I'm keeping
my newly repaired VSP for the time being). Compared to this Onkyo, even
classic or even legendary vintage amps and preamps in the same price range
can't save me any money ($450 for a great line stage AND 100/200 wpc
amp? C'mon!), and any used amps in this price range can't TOUCH the Onkyo
in any subjectively evaluated performance aspect.
Interesting. I had high hopes for the Onkyo. Glad to hear it panned out. Thanks for sharing.