Adding a ZERO which is after all a transformer after the otl ? Does it not defeat the whole purpose and sonics of otl in the first place ? How much of the otl sound remains after that ?
Advice re the use of OTL amps vs others
In my recent transition from solid state to vacuum tube amplification I'm learning a little about the various types of circuitry designs available. I'm currently using the Cary Rocket 88R amp mostly in Triode mode, and Peachtree Audio Nova as a preamp. The warmth I gained is extremely satisfying but I'm not sure if this is attributable specifically to the Rocket or simply as a result of transitioning to this setup vs solid state Peachtree to Martin Logan ESL's.
I'm impressed with what I hear about the Atmasphere amps and would like to consider them but have some concerns. What I've read is that the OTL amplifiers supposedly present the best of both worlds between a solid state and valve amp sound. In one way of thinking, using the Peachtree pre and the Rocket amp, I have somewhat the same thing now. I know it's not that simple but that's why this thread. I'm not concerned about overall sound quality with the right OTL but am that I might loose some of the warmth or "roundness?" I've found with the Cary.
Therein lies the question. I have no way that I know of to locally (33064) audition the Atmasphere S30 which is the one I'm leaning toward based on my research so far. The speakers which I'm now using and intend to keep are the original Reference 3A MMC Serie having an efficiency rating of approx 85dB and 8 ohms impedance.
I'm impressed with what I hear about the Atmasphere amps and would like to consider them but have some concerns. What I've read is that the OTL amplifiers supposedly present the best of both worlds between a solid state and valve amp sound. In one way of thinking, using the Peachtree pre and the Rocket amp, I have somewhat the same thing now. I know it's not that simple but that's why this thread. I'm not concerned about overall sound quality with the right OTL but am that I might loose some of the warmth or "roundness?" I've found with the Cary.
Therein lies the question. I have no way that I know of to locally (33064) audition the Atmasphere S30 which is the one I'm leaning toward based on my research so far. The speakers which I'm now using and intend to keep are the original Reference 3A MMC Serie having an efficiency rating of approx 85dB and 8 ohms impedance.
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Pani's question is a logical one, but the answers to it that are provided in the FAQ at the zeroimpedance.com site are good ones IMO: 12) What is the difference between the ZEROs autoformer and a typical tube amplifier's transformer?From a technical standpoint, and aside from a couple of spelling errors, that all makes perfect sense to me. Great comments by Tubegroover, as can be expected. I would just add that the Transcendent OTL amplifier with which he did not experience good results using Zero ratios greater than 2X was vastly different in design than Ralph's OTLs, including in numerous respects involving both the topology and the tube types used in the output stage. See this reference on what I presume is either the same or a similar Transcendent model. Best regards, -- Al |
Followup questions for Ralph: 1) Doesn't the 85db rating suggest that the M60s would be necessary for adequate power? 2) Perhaps I'm oversimplifying, but doesn't the 8ohm impedance tell us that zeros shouldn't be necessary? For OP, as former owner of Cary Rocket 88(older version, not R), Atma-Sphere M1 and Berning ZH270, among other tube amps IMHE: 1) You've already received numerous great comments here characterizing the sound of the Cary vs OTLs 2) For me the OTLs portray much more realism vs the more old school tubey sound of the Rocket, which did tend to smooth things over with a lack of transparency and lack of dynamic jump 3) In limited experience with zeros, I found they blanched the sound in ways that I couldn't live with. I personally wouldn't choose any solution requiring them, although YMMV. 4) Ultimately my suggestion is to commit to your speakers (or not) and then go OTL only if the speaker is a good match for the OTL under consideration without autoformers. Cheers, Spencer |
Thanks Al for your comments. With regard to the autoformer and the Transcendent amplifier you very well may be right, different topologies and tubes used. Interestingly enough, the gentleman I sold the autoformer to was using an Art Audio tube amplifier with 6c33 outputs. It too was recommended to him because of power issues. Never did find out out it worked out in his application. I really wanted to like it as I spent some time making several purpleheart cases for the autoformer for myself and another autoformer owner and invested in some nice edison price posts to easily change the turns settings. The things sat around for years before I finally sold them as the cases were so pretty. |
Spencer, my impression is that Ralph generally doesn't post on weekends, so while we await his response I'll mention the following, regarding your second question specifically: First, the S30 which Broadstone is asking about, at least in its most recent version, is spec'd at a considerably higher power rating into 16 ohms (45 watts) than into 8 ohms (30 watts). Using the 2X tap of a Zero would, of course, result in the amp seeing a nominal load of 16 ohms with his nominally 8 ohm speakers. Second, the output impedance of the S30 is spec'd at a rather high 7 ohms, which when used in conjunction with a nominally 8 ohm speaker without a Zero would probably have significant and somewhat arbitrary effects on tonal balance due to the interaction of the 7 ohms with how the speaker's impedance varies as a function of frequency. If Zeros are not used, the M60s' considerably higher 8 ohm power capability (60W) and lower output impedance (4.1 ohms) figures to provide much better results with Broadstone's speaker than the S30, as I see it. Best regards, -- Al |
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