First, my apologies to Paul for getting the spelling of his name wrong, Its, Speltz, not Speltzer. And next, @hilde45, thanks for that link. I have read Osler’s fine article/review and saw he felt low-powered amps, (but particularly OTLs) might benefit from the Zeros, though he did try something I wouldn’t, using the Zero between a DIY SET and high impedance speakers: (“T-Rex 300B SET, a DIY design project in the works (still unpublished) using Plitron output transformers with only 8-ohm taps, and the Lowther DX4 BassZilla - a 97dB efficient loudspeaker with an 8-ohm nominal impedance rating”). His results were kinda predictable and he admitted it was a push to go in that direction. So, I expect different results, if not necessarily better, as I’m going to use the Zeros between low-powered push-pull amps (4 ohm tap) on the 84db 4 ohm Maggies. I really don’t know what I’ll get, but I’m still waiting to hear from anyone else that may have already tried this or something similar. Thanks though, I agree it’s a good article to start with.
Push-pull Tube Amps and autoformers
I’ve gone and done it and decided to marry my 1.7i Maggies to mono Quicksilver M60s that only output 60w per. Crazy, I know. But the sound is sweet, and mellow for my jazz, though yes, at lower volumes, and they certainly do not allow the Maggies a full sprint, like with the Parasound A21+ that I can switch to (Luxman AS-55) when I want to throw-down serious dBs. But still, I would like a bit more punch from the QS. So, that led me to Paul Speltzer’s Zero Boxes. I talked with Paul (great guy to talk things through with), and he wasn’t certain that the “push-pull” QS would benefit from the Zeros, (because they were originally designed more for OTL amps like Atmospheres.) But, after talking it through awhile, we thought it worth the 60 day return trial period to see if the Zeros might help add that punch, if I use the 8 or 16 ohm taps. They arrive in a couple of weeks, so I’ll know soon enough. But, in the meantime, any of you have input, or experience with using autoformers (or auto transformers) with push-pull amps like QS? (Please give me a pass on bad speaker/amp impedance matching, ok? I knowingly signed-up for low-powered tubes for my 84db Maggies because others I trust on this forum have had good things to say about doing crazy sh-t like that. And, its just a trial. So, chime in gently, please.
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@audiodidact I think the best way to use the ZEROs is to use the 16Ohm taps on your Quicksilvers if they have one. Then use the ratio on the ZEROs that seems to sound best. Keep the speaker cables as short as possible and as heavy as possible between the ZEROs and the speakers. You can use longer cables between the amps and ZEROs and they don't have to be so heavy. This might give you more bass extension since most output transformers become less efficient when using the lower impedance taps and they often lose low frequency bandwidth at the same time. You might also get less distortion- if so the system will sound less bloated, more relaxed and you might hear more detail. |
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