Bottlehead Forum

Bottlehead Kits => S.E.X. Kit => Topic started by: adamct on February 21, 2012, 11:42:35 AM

Title: Low output impedance from OTL tube amp?
Post by: adamct on February 21, 2012, 11:42:35 AM

Please excuse this ignorant post - I don't understand most of the technical background to...well, just about anything.

I am trying to choose between a SEX and a Smack. I have a variety of headphones with wildly different impedances (25 to 300 Ohm) and sensitivities (from Denons to HiFiMANs). I was initially attracted to the Smack, since it has an output transformer, and I had understood that tube amps have high output impedance unless they also use an output transformer. The high impedance of most OTL tube amps made they a poor match for low impedance, high sensitivity cans (like my Denons).

On the other hand, I question whether the Smack can authoritatively drive my HiFiMAN HE-400s and (if I get them) HE-500s. That led me back to the SEX, and I saw that it can be set up for 4, 8, 16 or 32 Ohm output impedance.

Finally, the question: How is it possible for the SEX to have such low output impedance, even without an output transformer?

Best regards,
Adam

Title: Re: Low output impedance from OTL tube amp?
Post by: Doc B. on February 21, 2012, 12:37:14 PM

Quote from: adamct on February 21, 2012, 11:42:35 AM

Finally, the question: How is it possible for the SEX to have such low output impedance, even without an output transformer?

It's not. The S.E.X. does indeed use output transformers.

Title: Re: Low output impedance from OTL tube amp?
Post by: Grainger49 on February 21, 2012, 02:35:49 PM

Adam,

You might be thinking of the Crack which is OTL.  Check the product page:

http://www.bottlehead.com/store.php

Title: Re: Low output impedance from OTL tube amp?
Post by: adamct on February 21, 2012, 06:09:48 PM

Well, that answers that one...D'OH!!!

Thanks,
Mr. Sheepish