I've found that Tube Research Labs amps are very fast (dynamic, especially compared to traditional tube sound. Info is available at www.savantaudio.com, though their prices aren't current.
25 responses Add your response
Among the fastest amps in the world are Atma-Sphere's line of OTL tube amps, which includes the 220-watt MA2 MK2 monoblocks. Atma-Sphere amps boast a slew rate of 600 volts per microsecond! Very few amplifiers even list their slew rate any more, but 50 volts per microsecond is typical for solid state, and 200 volts per microsecond would be quite fast. Tube amps are often down around 15 volts per microsecond. The only amps I know to be faster than the Atma-Spheres are the Spectrons and Goldmunds, but they don't have the magical midrange and relaxing voicing of a good OTL tube amp. Other OTL amps are probably quite fast as well - I just happen to be familiar with Atma-Spheres.
One of the fastest amps out there has got to be the David Berning ZH270 OTL. I have yet to find an amp that can keep up. This 10 lbs. wonder is quite possibly the most advanced amplifier there is. The ZH270 has blown away every amplifier I've compared it to(Sim Audio, Blue Circle, and Mark levinson)to name a few.
I agree with the number of votes for Atma-sphere, but as far as sonics go I find the Tenor OTL's superior, and equally as fast and dynamic. The power question is paramount, the Tenors are rated ar 75 w, and although I've seen on other posts they can drive a good many speakers of different effeciency, including Wilsons, I've not seen any comments about anyone having heard them driving Thiels, which if I recall are a somewhat difficult load. However, I wouldn't be surprised if the Tenors amply drive them, and they are so good,I think it behooves you to give them an audition if possible. The AR Ref 300 MKII's are very powerful and fast as noted above, and will drive virtually any load, if so required. I personally preferred the sound of the Tenors over the Atma-sphere, and sold my AR 300's to purchase the Tenors, which drive my speakers without blinking. Worth a test drive if possible.
I would suppose that any OTL amp would be faster than any transformer coupled tube amp. I am using s Transcendent 25 watt OTL (this is the quietest amp I've ever heard, absolutely dead silent at the listening position) and I must say that the "real time" factor is better than anything I have EVER heard from any other amp be it tube or SS. The great benefit of this speed and what is notable is that there is NO OVERHANG at any frequency, this makes the music come alive.
I haven't heard any of the other OTL's mentioned above, but the point I feel is clear, OTL amps make music more real in a way that isn't obtainable from other amplifiers and the reason is their superior speed along with that palpable presence that music lovers find in tube gear. I'm not sure that accurate is necessarily the right word but what else can it be? Maybe less fatiguing? It is so much better to my ears that I would never consider a speaker system with an impedance that wouldn't match with an OTL. There is no going back.