Hifinews review D'Agostino Momentum amp

[cjfrbw]

The review reads like hyperbole salad with a side order of jet setting pomposisty. Have the Brits gone technicolor pretense like the Cousins? How degrading.

 

[microstrip]

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.

My cj conrad johnson premier 350 amplifier (the best sounding transistor amplifier I have owned) had a similar noise specification (-104 dB at full power ) and I never experienced any noise or hum with it. Dartzeel's have similar noise specs and at less two members of WBT use it with very efficient speakers without adverse consequences.

BTW, SNR of 78 dB was measured at 0dB - most manufacturers just quote SNR at full power. Please do not compare it with a phono SNR number reported to a unknown level.

 

[andy_c]

One Watt into 8 Ohms is the standard reference level for power amp SNR. As an example, Stereophile tested the Bryston 7B SST2 at an A-weighted 95.7dB SNR referenced to 1W into 8 Ohms here.

 

[Orb]

Yeah I tend to agree that the lower watt figure is a better practical reference than full power, although using both together can be important as well.
Cheers
Orb

 

[dandag]

Momentum noise measurements

Hum and buzz have no place in a $400 amp let alone a $40K amp. Something is wrong.

The noise measurements were done on a pre production unit . The production units do not exhibit the noise measurements. That was taken care of along with a number of other small details. The noise was a very simple fix. I did explain that the units were pre production.

Dan D'Agostino

 

[Steve williams]

Hey Dan

A much appreciated welcome to WBF

As a guy who owned countless of your products over the years I can say that you have enriched my life in this hobby

I kick myself for having sold my KPS25sc and MD-10 and Ref64 DAC

 

[Orb]

The noise measurements were done on a pre production unit . The production units do not exhibit the noise measurements. That was taken care of along with a number of other small details. The noise was a very simple fix. I did explain that the units were pre production.

Dan D'Agostino

Thanks for the headsup and it is fair to say a fair amount of us appreciated this was a pre-production or very early model,
can you expand on what caused the hum-noise?
I understand though that you may want to move forward and not focus on the pre production model, was curious from a technical-design perspective.
Overall the amp came through with a great score at Hifinews, in with a rare few to hit that %.

Thanks
Orb

 

[dandag]

The source was the shielding on the power transformer

 

[RBFC]

Welcome, Dan! We met over a decade ago, a few times. Once at a CES, and once as I toured the factory with Dean Roumanis. Big fan, and glad to know that the measurements on the new amp aren't representative of the production runs.

Lee

 

[Orb]

The source was the shielding on the power transformer

Glad to hear its working well now, and here is hoping your new venture succeeds!
BTW any chance in a year or so that you will be able t0 also consider additional products at a lower price such as maybe a $10-20k integrated and similar priced stereo power amp.
There is a lot of us with interest in you and your products, and wondering if you will be considering those who are more focused at this lower price bracket.

Thanks again.

Orb

 

[fishnchips]

The production units do not exhibit the noise measurements

Will you be providing non-defective units to the press?

 

[microstrip]

Dan,

Nice to read from you at the WBF. Just found your current system at the "About me" section - can I ask about the cables you are using?

BTW, after seeing you use the Momentum with Wilson Alexandrias we can be sure they are noiseless!

 

[mauidan]

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.

Myles,

No problem.

Hopefully now that Mr.D'Agostino has joined WBF, everyone will rest easy about the Momentum's hum issues. ;-)

Dan

PS- I wonder how many people have ordered Bonnie Raitt's "LostBroadcast."

 

[caesar]

Mr. D'Agostino,

Welcome to the conversation. Sorry for the long list of questions, but audio "journalists" and reviewers rarely ask the important ones. Other that financial reasons, what are your objectives with these amps? What is it about this design that is different than your previous Krell designs? Are you trying to re-create a live experience in the home or are you trying to precisely reproduce every detail on the recording?

What new things have you learned? When did you get these insights (and how?) and why didn't you implement them in your Krell amps? How are your amps different and better than other mega buck amplifiers from Balaboo, Levinson, Technical brain, Soulution, etc.?

Also, as mentioned in a post above, you run your amps with a very efficient set of Wilson speakers? Why run such efficient speakers with such a powerful amp, when Steve Williams runs them with Lamm amps that produce 15 or 20 watts per channel? Did you voice your amps with other speakers? Do they work well with power hungry elecrostats or Magneplanars? Why didn't you design your amps for even more power? Fremer runs his Wilsons with an amp 3 times more powerful than yours.

Why did you price these amps as you did? What determines/ drives the high price? How big is your operation? Do you build these in your home basement or garage? How long are you going to be in the game for? Serious customer would like to know if you still have the passion or if you will sell a couple of dozen and then take off sailing around the world.

Thanks! I hope you succeed!!!

 

[Steve williams]

Well in all fairness to Dan, my amps are 32 watt tube design.The ML3 is a single-ended (SE) tube amplifier utilizing a very powerful direct-heated triode GM-70 (125W plate dissipation) and a separate power supply.

Dan has always (as best I know) worked with SS gear. There are many ways to skin a cat.

 

[caesar]

Well in all fairness to Dan, my amps are 32 watt tube design.The ML3 is a single-ended (SE) tube amplifier utilizing a very powerful direct-heated triode GM-70 (125W plate dissipation) and a separate power supply.

Dan has always (as best I know) worked with SS gear. There are many ways to skin a cat.

Thanks for the correction, Steve, but I knew it was low powered. As a personal preference, I would also go with more power rather than less if I were running your speaker - but again I have not heard your amps or a Wilson/ Lamm system yet. But I do wonder where Mr. D'Agostino is coming from from a design philosophy. His amp has a lot more power than yours, but a lot less than what Fremer uses.

 

[Steve williams]

Well just remember that it is the first watt. My amps (ML3) are rated at 32 wpc. Previously I used the ML2.1 which is an 18 wpc amp.

With both of these amps there is more than enough headroom. I have had the volume up at near ear bleeding spl and have not had the amps clip.

The X-2's are remarkably easy to drive. Prior to my switching to tubes I was an all Krell guy having owned KSA-150, KSA-300, 750mcx, MD-10, KRC-HR, Ref64, kps25sc,TAS Reference Standard and even a Krell DVD player. Dan makes terrific gear IMO.

 

[FrantzM]

Thanks for the correction, Steve, but I knew it was low powered. As a personal preference, I would also go with more power rather than less if I were running your speaker - but again I have not heard your amps or a Wilson/ Lamm system yet. But I do wonder where Mr. D'Agostino is coming from from a design philosophy. His amp has a lot more power than yours, but a lot less than what Fremer uses.

I have heard both Lamm amps with the X-2 at Steve's and they sound excellent, magical .. Like You Casear, I would however still go with more power ... There is something about high power power that is seductive for the variety of music I listen to... 32 watts even with the X-2 wouldn't be sufficient for me...

 

[Steve williams]

Frantz, IIRC you only heard my ML2.1, not the ML3's

 

[DaveyF]

Mr. D'Agostino,

Welcome to the conversation. Sorry for the long list of questions, but audio "journalists" and reviewers rarely ask the important ones. Other that financial reasons, what are your objectives with these amps? What is it about this design that is different than your previous Krell designs? Are you trying to re-create a live experience in the home or are you trying to precisely reproduce every detail on the recording?

What new things have you learned? When did you get these insights (and how?) and why didn't you implement them in your Krell amps? How are your amps different and better than other mega buck amplifiers from Balaboo, Levinson, Technical brain, Soulution, etc.?

Also, as mentioned in a post above, you run your amps with a very efficient set of Wilson speakers? Why run such efficient speakers with such a powerful amp, when Steve Williams runs them with Lamm amps that produce 15 or 20 watts per channel? Did you voice your amps with other speakers? Do they work well with power hungry elecrostats or Magneplanars? Why didn't you design your amps for even more power? Fremer runs his Wilsons with an amp 3 times more powerful than yours.

Why did you price these amps as you did? What determines/ drives the high price? How big is your operation? Do you build these in your home basement or garage? How long are you going to be in the game for? Serious customer would like to know if you still have the passion or if you will sell a couple of dozen and then take off sailing around the world.

Thanks! I hope you succeed!!!

Good grief Caesar, what a laundry list of questions for Dan

Almost makes one think that you are trying to goad Dan in some way
BTW, just because an amp is highly powerful, doesn't mean that it has to sound good, in fact IME, the higher the power, many times the worse the sound. If Dan's amp has enough power to drive your speakers, which it should IF you are using any speakers that are a REASONABLE load, then that is all it needs. OTOH, if you are using Apogee's or the like, well look for another amp

So, in other words, i think the quality and sound of an amp has NOTHING to do with its ability to put out power 2nd BTW, I have heard MF's beloved Musical Fidelity amps, they did absolutely nothing for me