845 Tube vs KT90

Bartokfan,

I think you are trying to use the wrong tool for the wrong job in your amp search. The vast majority of 88dB speakers are not intended to be used with SET amps. It's no wonder 300B amps sounded flat.

To build on Audiofeil's analogy, that's like bring a Yugo to a tractor pull.

Before asking for suggestions you really should find out(or tell us) the impedence curve of your MTM Thors. 88dB by itself is not that difficult to drive, but are they 4 or 8 ohms? Do they dip to 2 ohms at some frequencies? It's going to be the dips that cause all the problems.

Also, what is your price range?

Personally, I don't think SET amps can truly handle dynamic peaks of large orchestral at medium-high volumes unless you are using 100dB+ speakers. I've got 95-97dB speakers and that is a stretch.

If you really have your heart set on 845 SETs, then I'd look at the manufacturers that are famous for high-current/high-output SETs - Dehavilland 845G-SE, Art Audio Concerto($12k), KR Audio (non-845, but high powered).

Be prepared, good high-powered SETs will cost a lot. The output transformers and power supply necessary to handle that kind of current cost a lot of money.

Remember that dynamic peaks with well recorded vinyl can be 14-20dB higher than the average listening level. So, if you normally listen at 85dB, you will need 32wpc without clipping to handle 106dB peaks effortlessly. Which will likely be a 50-60wpc, at the least, to stay in it's lowest distortion range. Good classical cd recordings can bee even more demanding.

My personal opinion is that in the high-powered category, really well implemented push-pull is just as good SET, maybe even better. It's definitely cheaper to with PP to get an equal level of performance. And you'll have a lot more choices.

Why not check out ASL Hurricanes (200Wpc, KT-88), Art Audio Concerto or Opus Ten(KT-90 or 88), Cary SLA-80(KT-88).

Aren, Dark, thanks for helpful imput.
Both of you raise my awareness of what the 845 SET (most are low powered, thus higher sensitivity speakers are best option) are alla about. Aren you mention the Ming Da, is that the ones that weigh in at 375 lbs!!! I saw a pair for sale here last month, a sweet deal at $3500. But alas too heavy for my back to move around. Besides they are rather large and not all that attractive. They were 80 watt push/pull. I also heard a big Audio research + ARC pre on Magnapans at a dealer in New Orleans months ago, they sucked the amp dry with no dynamics on orch. I hearda Conrad Johnson on Martin logans once and sucked dry with orch. The cayin 300/Silverline Sonata combo could not bring any life to orch. For light jazz/vocal the 300/Silverline was UNREAL, liquid and sur-realistic.

I do not know all the specs on the Thor/Seas, just know they are not the ideal speaker for tubes. Jadis' famous high power trans deliver the power for orch presentation from the Thors.
I'll share alittle story(yet again) on the ability of the JOR's power for its size. I first got it in and a friend asked to bring it over and hear it on his Mirage 1's, beast ofa spaeker for tubes, close to the level of demand as the Vandy 3's. We unhooked his massive Audio Research VT200 and ARC pre and to his surprised delivered some slam , but even better details than his ARC setup. But obviously the JOR would blow with continued use.
Anyway based on the above comments, I may just stick to what I know I like best, which the KT90 does overall. Budget? yea that is up in a ?. If the yr goes as i hope, a used JA80/KT90's may be my best option for the music i listen to. as in all things audio, compromise. Dark may a good point " really well implimented push/pull is just as good as SET's maybe even better"
Appreciate all the imput, sets my course straight.

I've owned both JA-30's and JA-80's (numerous NOS KT-88's, EL-34's and KT-90's) when I had Crosby Modified Quads and they were great sounding amps. Yes the music and picking speaking to fit that music are the two most important things to do. I switched in the nineties to Wilson's and two Audio Note Ankoru's (PSE, two 845's for output and a 300B for voltage driver for each mono amp). Miss the quads at certain moments, but the Wilson's with 845's fit my taste much better all around than anything I could do with the JA-80 with any KT-88 or KT-90 tube type. The 845's are my choice for amps now. Perhaps looking at Wytech's products might produce music magic at a sensible price. Speakers must be >91dB sensitivity or better. Take a look at Coincident Speaker Tech for a speaker you might like with your tube choices.

http://www.coincidentspeaker.com/

There is a Bel Canto SET40 amp for sale with KR845 tubes on the 'gon for a ridiculously great price. It's the same amp I have, less the KR 845s. $2500!! They still, (although it is not on their web site) make this amp. Sells brand spanking new for $5500. And it weighs in at 85lbs. You got a thing with componenet weight? You mention it often. Heavier the better? lol...

Bel Canto also makes(or used to) and SET-80 monoblocks which use two 845 in parallel push-pull for 70-80 wpc. I think it sells for $8k a pair new.

The only problem is that there is no free lunch in audio design and the doubled output power comes with some other drawbacks. As to whether they matter or are audible is a debate for those with more technical experience than I.