Dan D'Agostino Master Audio Systems Progression M550 monoblock power amplifier Specifications

Sidebar 1: Specifications

Description: Solid state class-AB mono power amplifier. Inputs: XLR. Outputs: Custom binding posts. Power: 550W into 8 ohms, 1100W into 4 ohm, 2200W into 2 ohms (all 27.4dBW). Frequency response: 1Hz–80kHz, –1dB; 20Hz–20kHz, ±0.01dB. Input impedance: 100k ohms. Output impedance: 0.1 ohm. S/N ratio: 105dB A-weighted, 75dB unweighted. (These are transposed on the manufacturer's website.) Distortion: 0.15% at 1kHz at 550W into 8 ohms. Power draw at idle: 80W.
Dimensions: 17.875" (454mm) W × 9.0" (230 mm) H × 23" (584mm) D. Weight: 115lb (52.2kg).
Finish: Silver or Black; custom finishes upon request.
Serial numbers of units reviewed: PM0506P, PM0507P, auditioning; PM006P, measuring. Manufactured in the United States.
Price: $44,950/pair. Approximate number of US dealers: 27. Warranty: Three years from date of retail purchaseor four years from date of manufacture for original purchaser of a new product from an authorized dealer.
Manufacturer: Dan D'Agostino Master Audio Systems, LLC. 5855 E Surrey Dr., Cave Creek, AZ 85337. (Tel): (480) 575-3069. Web: dandagostino.com.

COMPANY INFO
Dan D'Agostino Master Audio Systems, LLC
5855 E Surrey Dr.
Cave Creek, AZ 85337
(480) 575-3069
ARTICLE CONTENTS

COMMENTS
Jeffreylee's picture

Let me get this straight. Serinus reviewed a $45,000 pair of amps and didn't notice that one of them wasn't working properly THE ENTIRE TIME? This guy has turned into an ongoing source of embarrassment and if it wasn't for Mike, Herb and Ken I would have canceled my sub strictly because of his incompetence, not to mention his elitism. This review should have been shelved and rewritten, preferably by someone else, until both amps were working properly.

John Atkinson's picture
Jeffreylee wrote:
Let me get this straight. Serinus reviewed a $45,000 pair of amps and didn't notice that one of them wasn't working properly THE ENTIRE TIME?

It's probable that the output-stage bias of one of the amplifiers, slowly drifted while he was using the pair. It was only when he started his auditioning anew with the repositioned Wilson speakers that he noticed the problem with that amplifier.

John Atkinson
Technical Editor, Stereophile

Jeffreylee's picture

With all due respect, that explanation doesn't seem to scan -- unless bias can drift in a matter of minutes. Serinus clearly says that everything was fine until the speakers were moved, which probably took 30 minutes given their size. And then there's D'Agostino's belief that the bias drifted during shipment. Stereophile has always had some writers I trust more than others but this is pretty ridiculous.

John Atkinson's picture
Jeffreylee wrote:
With all due respect, that explanation doesn't seem to scan -- unless bias can drift in a matter of minutes. Serinus clearly says that everything was fine until the speakers were moved, which probably took 30 minutes given their size.

If the bias had slowly drifted during his auditioning, the incremental change in sound quality would have been difficult to perceive. (Think of the "frog in water that is slowly heated" analogy.) It was after the amplifiers were turned on again after the speaker moving that JVS realized that something was not right.

Props to JVS for his honest disclosure.

John Atkinson
Technical Editor, Stereophile

MFK's picture

The second sentence of Jeffreylee's first post nails it. However, we should be grateful for JVS's music choices and reviews. They have led me to a lot of wonderful music that I likely would not have heard otherwise.

Jim Austin's picture

I want to leave the substance of this comment intact, but I dislike the incivility; I've deleted two other comments for precisely this reason. But I can't think of how to perform surgery on your comment while ensuring that it remains your own, so I'll leave it alone. (No promises, though, about future comments.)

I'm also leaving it because it provides a good opportunity to respond.

I believe that a few critical readers, including you, are missing two points. Or maybe it's three. The first is that we're being radically transparent. For good or bad, instead of covering our collective ass, we've left this out there for all to see. The decision here was to present the whole process, good and bad, so that people can judge for themselves.

I think Jason was courageous for putting this out there--these uncivil responses prove that point. Perhaps I was wrong to allow him to do so, and yet I think it was the right thing to do.

After all, he didn't miss the biasing issue. He heard it eventually. Many writers--specifically writers at other publications--would doubtless have reworked the story to make themselves look better. Jason is to be commended for his honesty and--that word again--transparency.

The second point is this: There is no reason to assume that this was an abundantly audible effect. It may have been quite subtle. You weren't there. Neither was I. Such things can easily be swamped by room, stereo, and (other) psychoacoustic effects, especially when listening in stereo. There's a reason that at Harman and some other places it's standard practice to listen to just one speaker. We audition in stereo because that's how people listen to music, but one speaker can easily mask what's happening with the other. It certainly is possible, if not likely, that I could have missed it.

Either way, we told the truth.

Jim Austin, Editor
Stereophile

MatthewT's picture

The harshest critics didn't read, or at least cherry-picked, as it was all there in the article warts and all from the start. JVS takes more crap than anyone, all the more reason for him to write more.

tonykaz's picture

My older brother was a Horn Player for the DSO.

I recall one performance that seemed wonderful to me, I'd heard him practice that music for a Month.
He got a serious ass chewing for missing a few notes which he fully realised and expected.

The Audience never noticed anything amiss. Me included.

People's synapses adapt and adjust.

That is what makes MR.JA's laboratory work so very important.

Tony in Florida

tonykaz's picture

Are you gonna own these Mono Amps ???

and

Can I buy your old, tired & worn outs ?

I'll send a Wooden Ship builder to pick them up!

Tony in Florid

rickayre's picture

are you gonna trade in your current amps?

tonykaz's picture

I got first dibs on these tired & warn out old pieces of sadness.

but.,

I'll give you first right of refusal for a couple thou. $2,000.

I can't quite estimate a Final Sale Price because they once belonged to a Famous Reviewer for the World's greatest Publication.

Expect them to sell for about 125% of original Retail... of course they both will be properly Autographed and accompanied with beautiful Framable Photos .

You'll be getting the bargain of the Century.

Tony in Florida

ps. for a small additional few thousand dollars I'll try to entice both Mr.JA1 & JA2 to Sign em.

pma's picture

The strange distortion vs. amplitude plot that you can see here
https://www.stereophile.com/images/1021Dag550fig5.jpg
speaks for itself - it is a medium biased class AB amplifier with very low feedback factor or no global feedback at all. Then you see the rise of distortion above 1W and a minimum near to 200W, because the crossover area and distortion compared to the high output voltage gets relatively lower. Shame on the designer.

This and similar amplifiers are its own category with "special" customers. They do not care about measurements at all and probably would not hear any problem. John Atkinson stays too much on a polite side in my opinion, this should be clearly condemned how poor is the result.

tabs's picture

I posted something in response to the glaring deficiencies of this equipment, and it very much appears Stereophile staff deleted it. In no way did I use any foul language, and in terms of spirit, I was no more personal in my attack than @Jeffreylee who rightly called JVS an embarrassment and received a reply from JA instead of a deletion.

Jim Austin's picture

... you referred to another forum member as "a cancer."

Jim Austin, Editor
Stereophile

Jim Austin's picture

Your assertion that anyone is "stealing money" from anyone is of course ludicrous. People who buy D'Agostino equipment (and equipment from other expensive brands) do so with eyes wide open and all their faculties about them. I'm sure their enthusiastic customers would be amused at your presumptuousness.

Jim Austin, Editor
Stereophile

partain's picture

" a conspiracy of audiophiles " is at least as good as " a murder of crows " .

Jim Austin's picture

Jim Austin, Editor
Stereophile

thatguy's picture

what causes bias to drift in a new amp?

Jim Austin's picture

Due to the uncivil nature of some of the posts, this article has been closed to further comment.

Jim Austin, Editor
Stereophile

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