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One more time: autoformers?

Not sure if this OP belongs in cables, speakers, or amps. Since I listed cables first -- it's cables. There are already some old threads which touch on the use of autoformers. Seems like most of the threads come up in the context of OTL and SET amps.

My Qs are: What are benefits and downsides to using autoformers? How does one know if an autoformer would be a good match for his/her rig?

As with most things in life, I suspect that autoformers must have downsides. Otherwise, everyone would use them. Open and intellectually honest responses are welcome.

Thanks?
bifwynne

Showing 4 responses by bifwynne

bifwynne OP
2,206 posts
 
Thanks Zd... and Clio.... I own a power amp with output transformers. I also read the Paul Speltz white paper as well as the Atmasphere white paper on Voltage Paradigm and Power Paradigm amps. I get his basic point about impedance matching and the benefits of increasing the level of impedance the amp "sees."

My concern is that I do not have the full picture. If autoformers are so great, why don't amp manufacturers just slap that on the back of their amps for all the perceived benefits.

I would appreciate hearing from our "EE" type members about the benefits and downsides of using autoformers. One thought is that if a speaker's impedance curve is a rollcoaster with some pretty tough dips and hills . . ., sure, the autoformer presumably can lift the entire plot up 2X, 3X and so forth. What happens, for example, if the impedance hills touch 20ohms or 30 ohms?? Can any amp (SS or tube) push power into a 40 ohm (2 x 20 ohms) or 60 ohm (2 x 30 ohms) impedance??

Thanks again .
bifwynne OP
2,206 posts
 
Thanks Roscoe. There's a number of "EE" type members who I hope chime in too.

No +1 point for reading the Atmasphere white paper too??
bifwynne OP
2,206 posts
 
Thanks again Clio. I recall reading somewhere that certain Atmasphere amps had a 32 ohm ceiling. I tried the 4 ohm tap. The music su*cks. Went back to the 8 ohm tap.

Btw, been using my sub-woofer a bit more aggressively than before, i.e., raised the gain a little and raised the cut-off frequency to about 80 Hz. Going by ear, I think the sound stage opened up quite a bit. I don't know why. Maybe my finished basement is a giant bass (or is it base? - LOL) trap.

bifwynne OP
2,206 posts
 
Hi Drambuie. Thanks for your post. I'm waiting for ARC to come back to me with its thought about how well my ARC amp matches with my speakers. If ARC says all is well, I'll stand pat. But if not, I may be in the market for Zeros. If you decide to unload your Zeros, please send me a message and I'll give you a status update. I'm hoping to hear back from ARC very soon. If ARC thinks Zeros might improve my sitution, maybe we can help each other out. Thanks again.
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