Hifinews review D'Agostino Momentum amp

[FrantzM]

i'm with Mep- a 45k amp with hum and buzz should have never been printed.

+1

Had it come from a Pioneer middle of the line AV receiver in a review from the same person, it would be a cause for utter rejection ..Why the double standard ?? At that price there should be utter silence .. period

..Please people! Stop finding excuses for these companies! Shouldn't we be much more demanding ? This is a serious chunk .. Enough to purchase a complete, full range, high performance High End Audio system and this single component hums and buzzes?!???

 

[MylesBAstor]

+1

Had it come from a Pioneer middle of the line AV receiver in a review from the same person, it would be a cause for utter rejection ..Why the double standard ?? At that price there should be utter silence .. period

..Please people! Stop finding excuses for these companies! Shouldn't we be much more demanding ? This is a serious chunk .. Enough to purchase a complete, full range, high performance High End Audio system and this single component hums and buzzes?!???

The only thing that I might add is that a few Krell amplifier designs had hum issues when connected to electronic xovers like those used in the Infinity RS1bs. Now that was running the Krell in single-ended, not balanced mode, and that might be the issue/cause. But I don't see that as an issue with the Sashas. And, there was no hum when Dan used his amplifier with the Sashas at CES. But in this case, I think Dan ran the dCS right into his amplifier?


To be fair, designers can't always predict the intereraction of their product, say in this case an amplifier, with another manufacturers preamp. And remember Dan hasn't yet released the companion preamp to his line. For instance, many, many years ago, Dan ran into a problem with dealers selling ARC SP6a preamplifiers with his amplifier. The coupling caps in that preamp had a proclivity to fail, allowing DC to pass and blowing up his amps that were DC to whatever. So in the end, Dan had to put his foot down since he was warrantying his amplifier but not the preamplifier that caused his amplifier to blow up. So maybe there was something quirky in the interaction between the ARC and Dan Momentum amp? OTOH, that maybe should have been sorted out before publishing and not rushing to print and get a scoop?

 

[FrantzM]

The only thing that I might add is that a few Krell amplifier designs had hum issues when connected to electronic xovers like those used in the Infinity RS1bs. Now that was running the Krell in single-ended, not balanced mode, and that might be the issue/cause. But I don't see that as an issue with the Sashas. And, there was no hum when Dan used his amplifier with the Sashas at CES. But in this case, I think Dan ran the dCS right into his amplifier?


To be fair, designers can't always predict the intereraction of their product, say in this case an amplifier, with another manufacturers preamp. And remember Dan hasn't yet released the companion preamp to his line. For instance, many, many years ago, Dan ran into a problem with dealers selling ARC SP6a preamplifiers with his amplifier. The coupling caps in that preamp had a proclivity to fail, allowing DC to pass and blowing up his amps that were DC to whatever. So in the end, Dan had to put his foot down since he was warrantying his amplifier but not the preamplifier that caused his amplifier to blow up. So maybe there was something quirky in the interaction between the ARC and Dan Momentum amp? OTOH, that maybe should have been sorted out before publishing and not rushing to print and get a scoop?

Well ..more excuses ... The same would apply to AV receivers .. I would like for once that we be fair thus putting our foot down ... $45 K sould not buzz or hum .. Seriously how do you think progress is made: Through excuses? Or demanding for better products? for $45K I sure demand that my amp not rattle or buzzes .. Now on a true Audiophile front ... We think we can hear things that are below the threshold of hearing or that can't even be measured (not me people ) .. Now we would like to think that an acoustically audible hum or buzz will not have deleterious effect on the performance of the amp ?? mhhh!
Come on! No more excuses the thing must not show such blatant flaws at that level of price .. as simple as that ...

 

[microstrip]

For your information Paul Miller just wrote in his review:

Hum and noise is fractionally high in this early sample (yielding an A-wtd S/N78db re. 0dB 104 dB re. 300W).

If you dig on Soundstage measurement archive you will find that these specifications are in line with several high-end amplifiers with excellent reviews, or even better them.

 

[DaveyF]

+1

Had it come from a Pioneer middle of the line AV receiver in a review from the same person, it would be a cause for utter rejection ..Why the double standard ?? At that price there should be utter silence .. period

..Please people! Stop finding excuses for these companies! Shouldn't we be much more demanding ? This is a serious chunk .. Enough to purchase a complete, full range, high performance High End Audio system and this single component hums and buzzes?!???

It does indeed seem that hum and noise should have been banished in a product that is expected to sell for that price. However, my Rowland model 8 with choke, has always had a slight hum issue since new( apparently due to the choke power supply); Jeff knew about this problem and was forced to change the power supply by his Far East dealers. I think that when he did that, he did away with the Hum, but in some ways made the amp less able
So, maybe the moral of the story is that as a designer, you have to be careful "NOT to throw the baby out with the dishwater"
Perhaps a little hum is worth it with this amp.......

 

[Bruce B]

Well I think prospective buyers of this amp would have relatively quieter rooms, hence the "hum" could be a deal breaker.

 

[DaveyF]

Well I think prospective buyers of this amp would have relatively quieter rooms, hence the "hum" could be a deal breaker.

Agree, if it intrudes while music is playing , Otherwise, perhaps not so much.

 

[FrantzM]

At the risk of repeating myself . We are talking about $45,000 dollars here ... For that kind of price there shouldn't be that kind of issue.
Concerning the Rowland 8 hum ... How was it determined that the amp was, as you put it, "less able" when the hum was removed?

Just to play with some numbers here .. $45K .. One can build a mega system with:

Magnepan MG 20.1 ... $15 K
A pair of Bryston 28 B SST $18K
Weiss DAC 202 about $6K
Some good preamp for $5K I think the Weiss has a Volume Control

or
Revel Salon 2 $22K
BRyston 28B 18K
Weiss DAC 202


The rest on wires and cables from Blue Jeans .. You have a computer already else you wouldn't be on this forum

From all reports the Bryston 28B is one of the best amps around regardless of price and it doesn't hum. The designers made sure it doesn't buzz or hum and it delivers 1000 watts at 8 Ohms enough to drive ANY speaker on the planet with reserve to spare .. and it is guaranteed for 20 years ... Did I mention it doesn't buzz or hum?

 

[RBFC]

I've been a Krell fanboy for over 20 years. Dan has made some great gear. I'm disappointed if a $45K amplifier (his forte) hums. I wouldn't buy it.

Lee

 

[Peter Breuninger]

Guess I should reread Kessler's report about the hum issue. The two pairs I heard were dead silent.

 

[FrantzM]

Guess I should reread Kessler's report about the hum issue. The two pairs I heard were dead silent.

They better be ...

 

[mauidan]

Well ..more excuses ... The same would apply to AV receivers .. I would like for once that we be fair thus putting our foot down ... $45 K sould not buzz or hum .. Seriously how do you think progress is made: Through excuses? Or demanding for better products? for $45K I sure demand that my amp not rattle or buzzes .. Now on a true Audiophile front ... We think we can hear things that are below the threshold of hearing or that can't even be measured (not me people ) .. Now we would like to think that an acoustically audible hum or buzz will not have deleterious effect on the performance of the amp ?? mhhh!
Come on! No more excuses the thing must not show such blatant flaws at that level of price .. as simple as that ...

I don’t think Myles is making excuses, IMO, he’s just offering some perspective.

He says there was no hum when the amplifiers were used with the Wilson Sashas at CES.

Sasha’s Sensitivity is rated at 91 dB @ 1 watt @ one meter @ 1 kHz. The Sophia 3s that KK used for the review are rated at 87 dB @ 1 watt @ one meter @ 1 kHz. If listeners at CES didn't hear any hum, it's not surprising that KK didn't hear any hum at his listening position using the S3s.

I don't understand why you’re so upset. Are you considering purchasing these amps? If not, it shouldn't concern you.


PS- I like KK’s comment that the amps made his S3s sound like: ”Quad 57s with no limits to either their bass extension nor the maximumSPLs.” I had a similar experience when I heard the S3s driven by ARC 610Ts.

 

[fishnchips]

He says there was no hum when the amplifiers were used with the Wilson Sashas at CES.

So, there is sample-to-sample inconsistency as well?!?

 

[mauidan]

So, there is sample-to-sample inconsistency as well?!?

I can't answer your question. I haven't seen any published measurements on the amps that were at CES.

If you're considering purchasing these amps, I suggest you have them tested before taking delivery.

 

[microstrip]

So, there is sample-to-sample inconsistency as well?!?

As said in the review, these were early samples. Perhaps the problem was solved in production units.

 

[MylesBAstor]

I don’t think Myles is making excuses, IMO, he’s just offering some perspective.

He says there was no hum when the amplifiers were used with the Wilson Sashas at CES.

Sasha’s Sensitivity is rated at 91 dB @ 1 watt @ one meter @ 1 kHz. The Sophia 3s that KK used for the review are rated at 87 dB @ 1 watt @ one meter @ 1 kHz. If listeners at CES didn't hear any hum, it's not surprising that KK didn't hear any hum at his listening position using the S3s.

I don't understand why you’re so upset. Are you considering purchasing these amps? If not, it shouldn't concern you.


PS- I like KK’s comment that the amps made his S3s sound like: ”Quad 57s with no limits to either their ba ss extension nor the maximumSPLs.” I had a similar experience when I heard the S3s driven by ARC 610Ts.

Thank you Devert. And perhaps you, Frantz, should reread my post instead of jumping on your soapbox as you so often are want to do.

Didn't I say the problem should have been sorted out before publishing a review rather than rushing to print???

And may I daresay that perhaps you should have more experience with high-end gear compatability in your system. If you want everything to work all the time, buy a Yamaha receiver. The fact is that there's always unaccounted for variables that crop up every so often. That is the nature of the beast. That is the nature of science and being at the cutting edge. NO MANUFACTURER can try every piece of gear on the planet to assure 100% compatability with their gear--even if it costs $2000 or $200,000. If Dan's amp didn't work with his own line stage, then there would be something wrong.

And I'm far from a Krell cheerleader.

 

[MylesBAstor]

So, there is sample-to-sample inconsistency as well?!?

And how do you figure that?

 

[Orb]

As said in the review, these were early samples. Perhaps the problem was solved in production units.

Yeah agree with you bud, why I was curious of what someone who has heard the product thought about hum-noise.

That said, anyone else heard DC-coupled amp before and whether it had hum and noise?
I know of another well respected engineer who has a DC-coupled power amp and this hums as well; whether this relates to the design or combination with susceptibility to external issues-mains-etc may explain this, which could be the compromise for such a design.
However this is speculation and hopefully we will have more posters here listening to them, or more reviews with measurements.

Cheers
Orb

 

[fishnchips]

If you want everything to work all the time, buy a Yamaha receiver

A well-known fact of life. Yugos have always been far more reliable than BMWs.

 

[mep]

For your information Paul Miller just wrote in his review:

Hum and noise is fractionally high in this early sample (yielding an A-wtd S/N78db re. 0dB 104 dB re. 300W).

If you dig on Soundstage measurement archive you will find that these specifications are in line with several high-end amplifiers with excellent reviews, or even better them.

An "A" weighted S/N ratio of 78dB is horrible for an amplifier. That is what you would expect to see from a MC pre-preamp, not a SS amp. Calling a S/N ratio of 78dB "fractionally high" is kind of like saying Roseanne Barr is a little fat.