My best suggestion is to buy a used pair of Atma-Sphere M-60 amps and try them so you can hear how OTL will sound. If you don't care for the amps, then you can resell them for what you paid, or close to it.
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I think Tvad's idea is sound. I would also go to the Atma-Sphere homepage, read Ralph Karsten's white papers and some of the reviewers' impressions to give you an idea. Ralph's writings are uncontaminated by the usual hype. He is a man who can be trusted.
I myself run p/p monos and Ralph's 220 watt monos in my configuration driving the big Sound Labs. I like the sound of both, but for delicacy, air, bloom to my ears the Atmas play in a league of their own, especially in my configuration and room.
Call Ralph if you have unanswered questions. He is awesome and honest and won't oversell.
IME, OTLs provide a tremendous ability to untangle complex music in a natural way that beats anything else on orchestral music. Natural timbre is another strong point.
With Atmas, run balanced if possible. Cheers,
Hello, You should seriously also consider looking at the NAT Audio push pull power amplifiers in addition to the OTL products (www.nataudio.com).
The model is called Generators.
While I'm partial to these components because I import them, we've had many customers that have raved about these.
let me be the lonely voice, so far, to suggest you to try Jud Barber's Joule-Electra OTL amplifiers. I do not know that many designers in this industry who received as many prestigeous award (e.g. Golden Ear by Harry Pearson of TAS, something else from David Robinson of Positive Feedback) as Jud did.
Just because Jud does not participate in this form does not mean he is disqualified !
I will not even try to describe the sound of his equipment - you have professional reviewers for this and its not my job - I just want to see elemntary fairness to this industrial artist.
Correct, only the really old Futterman type OTL amps had trouble damaging speakers.
Although some would argue that Berning amps aren't true OTLs(I'm not getting into that old debate), I believe they are S.E., and they portray most of the traits of other great OTLs like the Joule Electras & Atma-Spheres.
Matching w/speakers that have a high impedance (ideally >8ohms) throughout the frequency range is critical with any OTL amp. Cheers,
FWIW Israel did a lot of the formative work on his speaker line with a set of M-60s. We have a set of his Total Victories which the M-60s drive with ease.
But to the point of OTL vs P-P, for the most part, OTLs **are** push-pull. The elimination of the output transformer eliminates the hysteresis loss that all push-pull output transformers exhibit. Hysteresis loss is the phenomena of an output transformer where it takes a little extra energy to reverse the magnetic field in the transformer as the signal goes from positive to negative or from negative to positive.
Normally this is not a problem at moderate or higher powers, but low level detail does suffer. The reason is that the extra energy needed to change the polarity of the signal comes from the signal itself.
OTLs traditionally have more bandwidth that transformer-coupled amplifiers, and so on the right speaker (such as a Coincident) will have deeper bass with more impact, and obviously faster and more extended highs. If done right, those highs will not be brighter- just faster and more extended. There is a difference there, one that I regard as the difference between stereo and music.
There has been a lot of comment about how OTLs prefer higher impedance speakers, and while this is generally true, most OTLs of moderate power will easily handle most 8 ohm speakers. However, I should point out that while many believe that the ability to drive 4 ohms and less is a hallmark of quality, the facts of the matter are that no matter what kind of amp you have (tube, solid state, class D), if **sound quality** is your goal, then that goal and your amplifier investment dollar will be best served by a speaker that is 8 ohms or more (16 ohms is very nice), than by 4 ohms, all other things being equal. If **sound pressure** is your goal, and you have a transistor amp, then 4 ohms is preferred.
Most (not all) OTLs and tube amplifiers will make more power into higher impedances (our MA-2 and MA-3 actually make slightly less). But in most cases, driving higher impedance means (transformer-coupled or not) that distortion will be reduced and bandwidth (top and bottom) will be increased. Any time you reduce distortion, you increase detail as distortion masks detail, and the amp will sound smoother.
Except for the power issue, transistor amps will otherwise behave similarly- more detail and smoother, when driving higher impedances.
Just for some context on how good I think Ralph amps (M-60s in my case) are compared with some transformer-coulped amps, I own and love the CAT JL2, which is surely one of the finest amps made. Because I'm getting older and wanted a lighter amp (it weighed 180lbs.) I kept look for a replacement and none could touch the CAT, till I tried the M-60s - I actually perferred it and I wa not expecting that, just something that would come close. With your speakers, the Atma-sphere will be a revelation to you -- I can almost guanrantee it.