90db, 7ohm speakers: tube amp recommendations?


I have the new Tyler Acoustics Decade D1's, and they sound very, very nice (still breaking in, but so far, couldn't be more pleased). I was considering a tube amp with them, would be paired with my McCormack ALD-1 Revision Gold+. I was thinking about a lower-powered push/pull design, something with over 20 watts obviously, but I don't need a ton of power for these. Room is around 400 square feet. Any good ideas? Budget is $2000 or so (used). Saw a Canary 301 that had been upgraded (22wpc, lots of current capability) but it sold very quickly. I was also considering higher powered KT-88 designs, but have been told that I may do better with a a bit lower powered amp, vs, say a ARC VT-100 MKii.

Looking for a fairly full, musical sound, but not too bloomy or warm. These speakers are extremely transparent yet musical, and I want to continue in that direction; a bit of tube fullness, but with no loss of soundstage or detail. It will be more or less to try: my upgraded (by SMC) McCormack DNA-125 amp currently sounds superb, but it would be nice to try something else for a bit.

My speakers are 91db and 6 ohm+. I'm also trying to decide if something with 32W like a VAC 30/30 would provide enough drive. I'm currently using a VAC PA100 which I prefer over the Phi 110. PA100 amps can be found under 2 grand. Other contenders to consider: CJ MV60, AES Six Pacs, VTL 85.

I would suspect you would need more than 30W in a room that size. I have a 30W Cary amp on 89db speakers in a 10x14 room and it rocks. My main room is 14x15 with a ceiling that vaults to 11.5 ft and open at the top to a kitchen/dining area. I don't know how loud 30W is going to go. I might try the Cary in the big system just to see.
With the easy load of those speakers, I'd recommend a used pair of Atma-Sphere M60s. With the right speakers, OTLs have superior performance in many regards. Their S30 might even be enough. Search the archives, plenty already said on the topic. Cheers,
'90db 7ohm' (nominal impedence) is an oversimplified description of your speakers impedence when you are considering proper amplification. You really need to know what the impedence curve looks like, or at least where the major deviations are and how big they are, especially the dip's. It would not be unusual for a speaker with a nominal impedence of 7 ohms to have a droop to 2 to 3 ohms in the bass making it a tough load for a lot of amps. IMHO, proper impedence matching is probably a bigger issue for you than the difference between a medium v high power amp. FWIW.
You might want to consider the Prima Luna amps. They're very good sounding
tube amps that fall into your price range and will almost certainly drive your
speakers in the described room to satisfactory SPLs. I say "almost
certainly" because in the unlikely event that a) the impedence curve is
really nasty - per Newbee, and/or b) you need true "ear bleed"
volume levels, you might be pushing it with these amps. OTOH, that caveat will
apply to most tube amps in your $ range. The P/Ls also allow easy "tube
rolling" to provide you some latitude in adjusting the ultimate sonic
character by switching the output tubes. They sound great, are well built and
require little maintainance (auto-biasing).

Good Luck

At least, you need to find out the minimal impedance of your speakers. I have two pairs of speakers, both rated 91dB@8ohm. They sound night and day different with my 50W KT88 monoblocks.

One pair has a flatter impedance curve and these 50W KT88 monos drive them nicely. But then with my JM Lab Alto Utopia BE, its impedance drops to 3.6ohms at lower frequencies. These KT88 monos are very inadequate for Alto Utopia.

I use Counterpoint NP100 to drive them. NP100 is rated 100W@8ohm and 200W@4ohm. It is barely enough for the Alto Utopia!

So like Newbee said, you need to investigate more.
I was told the minimum impedance is around 7ohm, nominal is 8ohm, with a flat curve that is "easy to drive". I haven't seen specs on them, but from listening so far, they are driven very well with my little 125wpc SS amp, whereas my previous speakers needed more juice.
Dawgcatching, most tube amps (including the M-60s) will drive that fine with no worries.
Agree with SBank. The Atma-spheres would work great. Or, for a bit less, and currently selling for only $1,450 on sale, the Music Reference MR10 MKII - 35 watts with EL84 tubes - both great designers and wonderful gear. Can't tell you which you would like better. But you can't go worng with either with those speakers.
Quicksilver Monoblocks - they're available used for within your price range. Really wonderful amps - even my relatively ancient KT-88 monoblocks are pretty amazing driving 89db efficient Studio 20's. Word to the wise - always retube used amps -have no idea why so many tube amps only have "around" 200 hours on the tubes - must be a pretty rough couple of hundred.
>>Word to the wise - always retube used amps<<

No don't do that.

Only retube if necessary.
Impedance is just one part of the 'load' an amp sees.
perhaps even more important is the phase angle.... The difference is expressed in degrees and is primarily caused by the inductors / capacitors / back emf in or generated by a speaker.
2 speakers with similar impedance and sensitivity but way different phase angle curves will load amps way different.
This is one of the major differences, electronically, anyway between good, better, best amps. And why an amp with less 'power' will kick the butt of a much more powerful amp, which can't drive the weird capacitive/inductive/back emf load of a modern speaker.
So, not only do you need impedance data, but phase angle data as well....
I suspect the differences in some of the above posters experience is not only based on sheer power....but how each amp responded to the complex impedance of the speakers.
These speakers are going to be sensitive to anything you throw at them. Very revealing and very musical. Tip the scale one way or the other and you will more than likely hear every bit of what the amp has to offer. Maybe trying a more full bodied power cord could give a little more bloom without losing the top end. Cabling may do the trick over a different amp.
I really don't know much about your pre-amp at all, but apart from that small bit of ignorance and considering your attraction to the potential tonal balance of the ARC amp I would recommend that you consider the Quicksilver V4's (although they might cost a bit more than 2K they have good resale value). They might have a slightly warmer tone but are still fairly uncolored, and not nearly as problematic matainance wise as ARC amps can be. FWIW.
Quicksilvers are wonderful amps, no doubt. I have owne three over the years. But with this speaker, I do think the Music Reference RM10 MKII, will be a very bit as good, as reliable as they get, extremely long tube life, very cheap tube replacement costs, and at the current "sale" price of $1,450 new, pretty hard to beat. Dawgcatching I thnk you have some good recommendations.