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Arc Ref 75se vs D'Agostino Momentum Stereo

    I have the opportunity to upgrade (?) to a D'Agostino Momentum Stereo for a good price. I was previously using a bought new  Ref 75 se which blew 2 tubes at the 30 hour mark. Despite being biased every 2 weeks. However, not only did the tubes blow ( due to the deterioration of the of the cathode coating of 2 tubes, I was told ) and the biasing resistor, it took a big chunk of the gold trace on the pcb and shortened the transformers as well.  This caused quite a stir between me, my dealer and Arc which took several months to resolve as I'm not based in the US. In the meantime, I was using a loaner ref 110 to tide me over. To make a long story short, just as my replacement 75 se (new ) arrives, I get an offer from my friend on the Momentums.  I have been traumatized by this experience so I was thinking of staying away from Arc power amps ( I've read some posts on similar problems ) hence willing to the try the Momentums.
     I am basically a tube guy so an SS amp even though the Momentums are suppose to be warm they don't have that tube bloom which I can't seem to live without.  I've been doing an A/B the last few days between the Ref 110(I know is' not the same without the kt 150's and all ) and the Momentum cause in case I get the Momentum's I can sell the Ref 75 SE sealed in the box as in "new".  I can seem to decide as both have their strengths and weaknesses. The rest of my system consists of

Ref 6 pre
Von Shweikert Audio Vr 44 Aktivs
Estoteric K07 sacd/cd player
VPI Prime with ADS and Benz Micro LPS-MR
IC's are all MIT - oracle and shotguns
PC's are all Shunyata alpha series.
Speaker Cables MIT Matrix 28
Room size 35 sq.m.

    Points I am considering, synergy among the same manufacturer's, the Vr 44's  are active so I don't really need a lot of power just enough for the tweeter and midrange. But those Momentums look gorgeous and the deal is quite good. From my recent A/B tests, IMHO I noticed that the ARC does better with vinyl while the Momentums does better on Cd and streaming from my macbook to the esoteric. Help me decide, your inputs are welcome. This offer expires in a few days so I have to decide quick. Thanx.
 
attymbb
charles1dad's avatar
charles1dad
10,229 posts
 
If it really is as close as "splitting hàirs" I’d choose the solid state amplifier. No tube maintenance or replacement of tubes to worry and you can leave the solid state amplifier on 24/7 if you want to.

The only advantage of the tube amplifier is if you believe it is better sounding and has sonic/musical qualities that the solid state amplifier is unable match.

I’ve recently done this type of tube and solid state amplifier comparison and although both were truly fine sounding across the board I ultimately preferred the tube ajp. It was more 3 dimensional , more tactile or palpable presence of the performers and superior tone,timbre, harmonic overtones and vibrancy (breath of life quality) Overall more emotionally engaging and "life like ".
This outcome may or may not be the case in your specific system and direct comparison. It appears that either way you’ll have an excellent amplifier in your home system. Choose the one that seems to pull you deeper into your music.
Charles
almarg's avatar
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almarg
9,670 posts
 
Attymbb 8-25-2017
I was previously using a bought new Ref 75 se which blew 2 tubes at the 30 hour mark. Despite being biased every 2 weeks. However, not only did the tubes blow ( due to the deterioration of the of the cathode coating of 2 tubes, I was told ) and the biasing resistor, it took a big chunk of the gold trace on the pcb and shortened the transformers as well.
I’m wondering if a possible contributor to the failure may have been the fact that your active speakers most likely present a very high impedance to the amp at deep bass frequencies. Which would mean that during notes having substantial deep bass content the amp would have been running essentially unloaded at those frequencies. And as you probably realize, as a general rule tube amps that have output transformers should not be run unloaded, especially when they are processing a signal. Otherwise damage to the output tubes and/or the output transformer can occur due to a phenomenon known as "inductive kickback."

I’m just speculating, of course, and I assume there are many audiophiles who use ARC Ref amps in conjunction with speakers of various kinds that have powered woofers. But it’s a possibility I wouldn’t rule out, and if you are looking for a tiebreaker in choosing between the two amps that might be a factor to consider.

Good luck. Regards,
-- Al


4425
861 posts
 
I own a Momentum Stereo s250 and would never trade for a tube amp. Tons of power with uber finesse and musicality. A modern work of art as well. I personally like my speakers to much to worry about a 'lightbulb' popping at high volume. Just my paranoia I suppose but when ARC described tubes as like light bulbs concerning failure that was it for me when ss is so very good now. 
attymbb OP
25 posts
 
charles1dad,

          When I mean "it's like splitting hairs" , I don't refer to the sound they convey,more on the fact they both have their own strengths and weaknesses which makes the decision that more difficult.

almarg,

          When my ref 75 se first blew up I had Harbeth SHL5+ then.
zoera
5 posts
 
attymbb,

Well, of course, an all-tube chain will have more tube goodness, but to my ears, the benefits of all that extra power vs an increment in soundstage depth/width that the tube amp will provide is simply not worth the hassle of dealing with tubes in power amps.

As I said, you'll gain tons of flexibility and yours speakers (current and future) will thank you for it if you go with the Momentum!


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