Accustic Arts AMP V power amplifier

The $50,000, 176lb Accustic Arts AMP V (pronounced Amp Five) is the heaviest, tallest, most powerful, most expensive stereo amplifier to enter my audio system. With rated power of 900Wpc into 8 ohms, 1360Wpc into 4 ohms, and 1500Wpc into 2 ohms, the AMP V, which stands proud at the top of the Accustic Arts amplifier line, surpasses my reference D'Agostino Progression M550's rated power into 4 ohms by 260Wpc (footnote 1).

What, if anything, might those extra 260Wpc—and those extra pounds of transformer and heat-dissipating metal—mean sonically in my moderately sized listening room? I was determined to find out.

Rock the joint
"I listen mainly to rock and a few classical tracks—for example, The Planets," AMP V designer Sebastian Ruland told me during a WhatsApp chat that also included Hans-Joachim "Jochen" Voss, the owner of Accustic Arts. "This is the main thing I was thinking about musically when I was designing."

"We wanted sound that's authentic and natural," Voss added. "Some electronics sound overly analytical. We have tried to make the AMP V sound as natural as live music, from the bass to the heights, without overdoing the bass. Our goal is to produce really solid, good-sounding music that works with all good loudspeakers. For example, we've been at AXPONA with Magico and Van den Hul."

The AMP V is the successor of the AMP III (footnote 2), but almost everything about the AMP V is new. "The AMP III, which was in production from 2011 to 2016, was taller and looked more like a cube. It also lacked sufficient space inside," Ruland said. With no concern for designing to a price point, Accustic Arts "did what we needed to do [as we] created our biggest stereo amp, with a 30% price increase from the AMP III."

The AMP V remains a current-mirror, dual-mono MOSFET design. The V has 40 MOSFET output transistors, identical internal cabling, and identical, "improved" printed circuit board (PCB) traces for each channel. The improved tracings are part of a new PCB design that includes gold-coated traces and gold-plated contacts; they're said to raise the damping factor and improve "other parameters"—that's from Ruland. Everything is hand soldered. "In the AMP III, there was a problem with high frequencies and high power," he acknowledged. "The protection circuitry inside the amp would sometimes be triggered if, for example, you took a 16kHz signal with 20 volts on the output. The new PCB addresses this."

"The gold maintains constant contact resistance. There's no corrosion or anything like that, and no change over time," Ruland said.

Two pairs of new, gold-plated WBT speaker terminals allow for biwiring or biamping. The AMP III had only single-ended inputs, but the AMP V is a fully balanced class-AB design with an added pair of balanced inputs. Ruland estimates that as much as 8% of the amp's output is in class-A. That's close to 100W.

Ruland designed the amp's two identical, magnetically shielded toroidal power transformers, which were manufactured in a facility 80 miles away; it's the first time Ruland has designed the transformers in an Accustic Arts amplifier. Accustic Arts says the power supply has capacitance in excess of 220,000µF. To remove any possibility of hum—I heard none—transformer inductance was decreased by increasing the number of windings. "It's about the ratio between input windings and output windings," Voss said. "To get more power, we had to increase the output voltage as well." The AMP V boasts 40% more power than its predecessor and is, in Voss's opinion, "more musical."

Damping factor linearization
New to the AMP V and its MONO 5 sibling is "damping factor linearization," an option engaged by pushing the Damping Control "On/Off" button on the amp's rear panel. According to the 1½-page explanation in the AMP V's well-laid-out, printed instruction manual—it was not available online at press time—modern, high-power transistor amplifiers have very low internal resistance and therefore naturally high damping factors. "These high damping factors are desired because they have a very positive effect on important technical parameters, eg, on distortion characteristics. ... The degree and progress of the damping-factor influence ... the control of the connected loudspeaker by the power amplifier.

1221amp.2

"Claims are often made that a higher damping factor is better for controlling the loudspeaker, and therefore the system sounds better. That is not the case. Correct is that a power amplifier with a very low damping factor is not able to sufficiently control the loudspeaker. It is, however, true that a loudspeaker does not have the best outswing behavior with the maximum damping factor. The truth is that the value of the damping factor should ... be within a certain range which is ideal for the loudspeaker and should be linear for as long as possible over the frequency range.

"In order to meet these two requirements—ideal range and linear curve—we lower the complete value of the damping factor slightly to the ideal value and then linearize it over a wide frequency range." All this happens, of course, only when Damping Control is turned on. When the damping factor is not engaged, "the absolute damping factor is then maximized, but from 5kHz, decreases considerably."

Voss and Ruland both noted that damping-factor linearization is intended to improve control of difficult loudspeakers. When the damping control is activated, they say, the AMP V will better convey attack on low bass. To quote Voss: "We listened to Outbreak [by Dennis Chambers] in our listening room once with active linearization and once without, and we can hear the difference: Without linearization, the song sounds somewhat held back. Activating the linearization adds more dynamics to the mix. The entire recording gains more openness and room to breathe."

Setup
Acknowledging my physical limitations, I asked two fully vaccinated weightlifters from my gym to help hoist the AMP V onto the top shelf of my four-tier rack. When they arrived, they saw no way to position it without wedging a hand between it and the D'Agostino Momentum HD preamp that would sit alongside it atop my four-tier, eight-shelf Grand Prix Audio Monza double rack. So instead, they lifted one of the 115lb D'Agostino Progression M550 monoblocks from one of my low-lying Monza amplifier stands onto that top shelf and replaced it with the AMP V.

1221amp.bac

The AMP V requires two 15A power cables, one for each transformer; their receptacles are positioned one above the other on the rear panel. Also on the rear are three buttons: one to engage the Damping Control, another to engage "Mute," which keeps the unit at "perfect" temperature for optimized sound and should be used only for "very short listening interruptions," and a third to choose between the AMP V's single-ended and balanced inputs.

There are two sets of speaker outputs. Two ground contacts are intended for use with shielded, groundable speaker cables.

Behind the power button on the front plate, the AMP V has two power switches, which operate together to disconnect both channels from the power supply. This is not a standby button but a main power switch.

On the front panel, directly below the power button, is a small blue LED flanked by two red LEDs. The red LEDs light up during warmup, after the power button is depressed, which takes about five seconds. When the red lights go off and the blue LED lights up, the AMP V is ready to play music. If a red LED remains lit, there's an error on that channel.

Accustic Arts counsels switching on the AMP V last and turning it off first. They also recommend against turning the amp on and off frequently. "The high amount of switch-on current is a heavy burden for the electrical components" and can "shorten the amp's life."

One related thing, which the company says is "VERY IMPORTANT!: After switching the unit off, please wait 60 seconds before switching it on again."


Footnote 1: My Wilson Audio Alexia 2 loudspeakers have 4 ohm nominal impedance.

Footnote 2: The smaller, forthcoming AMP IV is, similarly, the successor to the AMP II.

COMPANY INFO
Accustic Arts Audio GmbH
US distributor: Rutherford Audio
14 Inverness Drive East, Unit G-108
Englewood CO 80112
(303) 872-6285
ARTICLE CONTENTS

COMMENTS
Gavinspen's picture

We have a dish in Ireland, Google it
It's called champ.i guess
You guys are going all Michelin star on us.What a load of crap,oh I know I will get berated so what my bottle of wine cost more than yours
Although my cellar ain't the best and the ambience is lacking.
Old farts!!
Shoot me now!
Sorry for trolling but I
Felt a movement....

georgehifi's picture

"I felt here that the Accustic Arts amp was more single-mindedly yang in character and the D'Agostino mono more successful in tempering yin with yang"

This statement to me is typical of an A/B between 2 big quality linear push/pull Class-A/B amps, one being Mosfet the other being Bi-Polar (BJT) output stages

Cheers George

Jack L's picture

Hi

Yin & yang always co-exist, being complementary each other instead of competition. This is how the nature works per the oriental philosophy.

But both Accustic V & D'Agostino in fact compete against each other in the marketplace within arm's length (same price range) !!!! So Yin & yang are not appliable to them, IMO.

I've not had the chance to read the power O/P stage schematics of both power amps. Reviews said Accustic V used MosFet devices. But what output devices used in A'Agostino M550 were never mentioned. How did you find out what power devices used in M550 ? BPJ ??

All roads lead to Rome. I don't believe mega-weighted mega powers should sound "more musical"(per Voss) than light-weighted lower powered amps given proper loudspeake matching.

Listening is believing

Jack L

Gavinspen's picture

As aspected subtle
Sublime esoteric and
Clever....

tonykaz's picture

Well, you are probably right, people with disposable funds in the $50,000 range considering this kind of purchase are probably dilettante inheritors.

Isn't this Amp being marketed specifically to the Status/Ego customer ?

It's amplification performance needs to impress the dealer/salesman so that they can promise significant greatness and exclusivity.

Should we readership be asking if Stereophile now caters to the Elites or Blue collars ?

Auditioning this Amplifier ( for the not-foolish ) should include a brief description of the flight on the New Gulfstream Personal Jet with juicy descriptives of the Prime Steaks at Ruth Crists ( or Fins ) .

Maybe with Audiophile population numbers diminishing, like they seem to be, our Tent may needs to include gaudy packaged extravagances like this.

or perhaps instead:

A phono cartridge transducer review specialist to do full line evaluations of the Grado series, Audioquest series, Dynavector Series and all the other Phono Cartridges commonly available to mail order buyers .

Tony in Florida

ps. the word "foolish" making it to print shows that hubris is creeping into the Editorial Standards of this Magazine

MatthewT's picture

To do what is says on the tin: "Stereophile covers everything high-end and audiophile audio." You do love to throw that word around.

tonykaz's picture

The reviewer identifies buyers as "foolish" if they don't consider this multi thousand dollar device. Shouldn't we consider that sort of talking-down as hubris ?

Home Audio is a DIY hobby, isn't it ?

Don't we all build our own systems with carefully selected components that help our recorded music sound better ?

Should we enjoy our Editorial Staff chiding us for being foolish ?

Shouldn't High-End be considered on a Value for money basis, isn't that why we look for authoritative consultation ?

I've been in Pro-Audio Recording Studios that use gear that isn't flashy, pricy, gaudy but performs to established standards beyond Home Audio's.

The best of the Home Audio gear looks better and seems to make music sound better, isn't that why folks pay high prices for gorgeous sculptured Show-off pieces like what Stereophile puts on it's Front Covers.?

Super pricy gear does have an established social purpose: to show everyone who has the highest Status and to enhance Ego structures.

Tony in Florida

MatthewT's picture

To read the magazine?

tonykaz's picture

Mr.JA and a few others are continually raising standards.

I've been a JA fan since the 1980s. when I imported HFN&RR !

Mr. HR, Mr.KM, Mr.RS and a few others are brilliant.

The new girl seems insightful.

Stereophile is still worthwhile plus interesting people like you are part of the insightful readership.

Tony in Florida

Jazzlistener's picture

you must have a lot of time on your hands as you are constantly clogging up the comment sections of this and Analog Planet’s comment sections with your unwelcome, irrelevant blather. Here’s an idea, how about trying the senior bingo nights a few times a week where you will no doubt find many other old men shouting at clouds.

tonykaz's picture

My point of view is representative of close to 85% of the earth's population.

Analog Planet and Jazz both are niche in the real world & old-school like the Bingo you mention.

So, Sir, you may be the irrelevant one. ( in a philosophical sense )

Thank you for writhing, it's what this comment section is all about, isn't it?

Generalised sarcasm like your bingo comment is anger or is it just late nite Booze?

We have another great decade of scientific development unfolding, right here at Stereophile is a wonderful vantage point to see some of it happen.

Tony in Florida

Jim Austin's picture

Here's the actual quote:

Anyone with a spare $50,000 (and who doesn't require easy portability) would be foolish not to give it a serious audition.

We review gear at all prices, Tony, except perhaps the "blue-collar" box-store stuff. (Do box stores still exist?) Not all the products we review will be in your sweet spot. There's no need to be offended, or to take it as some sort of moral offense: Stereophile has other readers who have interests different from yours. I welcome your interest, but Stereophile does not exist for you alone. Misquoting, or mischaracterizing, a reviewer to make some point is not welcome.

Jim Austin, Editor
Stereophile

Anton's picture

I tried to write a reply but they all leaned toward the profane.

I really don't know the price sweet spot.

Don't know if there is a direct reader price/interest correlation, or if it the inverse.

Looking at how reviews catch my eye, I can remember in detail the review of the Golden Ear Triton reference, but couldn't tell you squat about the Göbel Divin Marquis, the Tidal Audio Akira, or the Wilson Audio Specialties Chronosonic XVX. I mean, I am sure I read the reviews, but had to click into "Recommended Components" list to take another peak beyond the price event horizon to be reminded they exist.

Maybe there is a section of readership that dwells in the thin air up there! I like aspirational reviews, but then I hit the ones that no amount of work and pain could deliver them unto me, and my attention does drift sometimes.

Our hobby has a very wide range! Honestly, nobody does it better than Stereophile, for me.

Anybody with a spare 12.99 would be foolish not to subscribe.

tonykaz's picture

I've owned and sold gear like this Amplifier.

I'm objecting to using "foolish" as a descriptive term.

I'm not saying it's foolish to use a term like that but you probably should.

Tony in Florida

noamgeller's picture

Dear Editors of Stereophile

I saw yesterday an interesting documentary on NYC Billionaire Row.
https://youtu.be/Wehsz38P74g
It seems like High-End suffers from the same fate... More and more Luxury Firms are building for the 0.1pecent... and I don't blame them. Either you charge more or you're out of the game. Why should a potential buyer should settle for the seconed highest when the next building blocks your Central Park view? Here we are the rest 99Percent looking high in the sky at those skescrapers and shaking are heads... knowing that high up there no one really lives.

tonykaz's picture

Our entire Social World is changing yet again. It isn't just Billionaires in NY.

Last Decade the iPhone changed everyone's life.

The 1st Decade was dominated by our Computerisation.

The 1990s had growth of Income stop, forcing Mom into the workplace. The children became Computer Game people.

The 1980s brought technology to Everyman.

The 1970s brought never ending War, Suburban Life , Boeing 707 Vacation Travel and Super High Inflation.

The 1960s brought Interstate Highways, Camping, National Parks and a hope filled future .

The 1950s were rather simple : Red Bikes under the Christmas Trees, Baseball on the AC/DC tubed Bakelite table Radios, canning garden tomatoes in the pressure cooker

As of now:
Our Recorded Music world has already powerfulllllllly changed -- for the better! :
1.) RtoR DACs have replaced Koetsu Phono Cartridges
2.) Streaming has replaced our Linn LP12 record Players
3.). Class D Amplification has supplanted the Big Beautiful Sculptured Amplifiers
4.). Loudspeaker Transducer design implementations have come down in actual cost bringing increased availability.
5.). Shirt pocket Audiophile Systems are everywhere on the Planet
6.). Skilled Individuals have become Publishers with wider circulations that traditional Print Media.

Looking over the Horizon,
a.) what audio gear will we be listening to in 2030 ?
b.) what will our latest Audio music format be ??
c.) what will StereoExchange be pricing a used 10 year old $50,000 Amplifier at ???
d.) will we all be having wireless Active loudspeakers ????

Tony in Florida

ps. seems like the only thing that hasn't changed is change

Jack L's picture

Hi

It is not too expensive to buy 2x900W for $50,000 = $27.7 per watt considering the sound quality were not in the equation.

How about a USD125,000 17W+17W stereo tube power amp = $3,676.5 per watt !! I auditioned it in depth & I love the sound. NO way I found it could not deliver the music right !!

So its the sound qualifies for its price fairness, right ?

Output power rating is only a number which never tells how good would be the sound.

Listenig is believing

Jack L

tonykaz's picture

Can you reveal your method for establishing a Purchase of one of these pricy Amplification Systems ?

How long of an auditiion in your music system would it take to convince you that this device is worthy of owning ?

How many cabling variations would be involved ( and time commitments required ) to finally reveal the magic combinations ?

How much break-in time will you allow to finally conclude the device has burned in properly ?

Are you committed to take the time and expense of a project like this

or

Are you simply taking the word of our reviewer and Dealer after being dazzled by a Showroom presentation ?

When Krell arrived ( the 1980s ) with their wonderful Amplification we were all probably loving our cherished ARC & Conrad Johnson Tube Amps. The Big Powerful Solid State Krells ( with gorgeous gold screws ) could drive our big dynamic drivers and Ribbon Planers.

So, I wonder, is this $50,000 Amp a device that reaches out further that Mr.D'Agustino has gone? This seems like a Bigness Race.

Our little DIY Audio Hobby seems to have folks that have no financial limits on purchase considerations, they can indulge pricy gear. I wonder how many of them read Stereophile ? ( if any )

Tony in Florida

Jack L's picture

Hi

Yes. I did quite a few times spent time to find out which amps & loudspeakers sound closest to live performance (my yardstick to gauge any audios) out of 'curiosity'. Like the USD125.000 17W+17W tube power amp I mentioned above.

But No, I would never want to spend such monies to acquire any of them.
Why I should spend my money (even with some easy monies I earned from the money markets) to finance the vendors?

I am not that HELPLESS being an engineering DIYer !! Haha!

Jack

JHL's picture

...we readership be asking if Stereophile now caters to the Elites or Blue collars ?"

Only if we need audio woke. Knowing, like we do, how that kind of inevitable projection - which is just the pseudo-virtue of envy - goes...

Jack L's picture

Hi

Audio magazines are for readers of all walks worldwide, "Elites or Blue collars". Therefore reviews of products to suit different "classes" accordingly.

Jack L

Archimago's picture

"Only if we need audio woke. Knowing, like we do, how that kind of inevitable projection - which is just the pseudo-virtue of envy - goes...

Fascinating that when folks criticize extremely expensive and questionably performing devices like these, the defense is often that of "envy".

Envy is only true if one actually has a desire to own these things. I think many times, audiophiles simply critique these products because clearly the objective performance is not good and it's unlikely that claims of remarkable sound quality are true.

JHL's picture

...it conflates well with materialism and we live in enormously materialistic times.

tonykaz's picture

I've owned and sold amplifiers like this.

Owning gear like this is more burdensome than pleasurable .

Imaging the cleaning lady scratching the top of this thing.

Tony in Florida

noamgeller's picture

I should go to the beach and look at the Ocean to get some Perspective.
So I went to Ebay and got the same. Stuff you could buy with 50K (in Germany)
https://www.ebay-kleinanzeigen.de/s-autos/preis:45000:50000/seite:2/auto/k0c216

Have Fun!

Archimago's picture

Sounds like your dad is/was a wise man.

Nothing wrong with anyone buying very expensive devices like these of course. I'm sure there are audiophiles who have enough cash to grab something like this many times over but would still look at the performance and wonder why this is worth more than those precision engineered automobiles.

Again that's not "envy". Just an honest question about performance, actual sound quality achievable, and what's reasonable value.

bhkat's picture

Nothing wrong with it. A much better deal than a degree in gender studies for 1/5 the price.

sw23's picture

You are a product design engineer. You are given orders to produce a state of the art stereo product. You make a list of all the components. Get first class stuff. Two of everything. What possible advantage is attained by cramming it all into one box that can't be lifted and has be positioned between the speakers? Are you sparing the consumer the price of a second box at your $50K price point?

David Harper's picture

oops

David Harper's picture

My first thought was to post here some boring self-righteous blather about the obscene self-indulgence of a purchase like this. But in a country where billionaires capable of solving world hunger instead play with space rockets it would be pointless. But I must respectfully disagree with "anyone with a spare 50K would be foolish not to give it a serious audition". Even if I had Jeff Bezos' money I would not consider myself foolish to "not give it a serious audition". A simple matter of price/value. Or cost/benefit. Or something to that effect. But that's just me.

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