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OTL questions

post #1 of 16
Thread Starter 
Are there any other OTL headphoneamps besides Earmax (Pro), Wheatfield HA-2 and Audio Valve RKV?

And what colours are Earmax Pro available in? Any other finishes than the cheap looking plastic?

What about the tubes for the amps mentioned above. Are some in short supply?

Guess that's all for now...
post #2 of 16
AFAIK the only other OTL is the mysterious Zeus. To the best of my knowledge only the Earmax and Wheatfield use current production tubes, though NOS 6EM7's for the Zeus are readily available. PCL 805 is a very rare television tube. Supplies are scarce indeed.

The Earmax Pro comes standard in black or teal. Audioadvancements were the ones doing the custom wood finishes, but not anymore. Maybe Brocksieper can build one to your specifications.
post #3 of 16
Here is what the wood finish looks like. (along with black but thats a phono amp shown)

Joseph Lau (Mr ASL) has been quoted in being interested in designing an OTL version of the MG head.

(that would be sweet!)

Sure OTL type sound clear and detail but it seem to be difficult to matching with Headphone under 200 Ohm. So I have an idea. Is it possible to made a Headohone amps can operate in OTL when matching with Headphone 200 to 600 Ohm type. Operate at Transformer coupling when match with Low impedance type may be from 8 Ohm to 100 Ohm. I consider to modify MG-Head and made it can work in both condition.
post #4 of 16

Isn't the Berning MicroZOTL OTL?
post #5 of 16
Isn't the Berning MicroZOTL OTL?

Ah yes, that would be correct.
post #6 of 16
I don't think that amp is a true OTL. There are still transformers incorporated in the ciruit.

Please tell me I'm wrong.
post #7 of 16
Thread Starter 
Thanks for the info.

That Zeus sounds intresting. Strange that no one here has tried it. Well if I had the money I would be the first.

I think Earmax Pro will be my first port of call.
post #8 of 16
shamelessly copy 'n pasted from headwize:

The Micro-ZOTL is the first product from the David Berning Company to feature Berning's patented ZH OTL impedance conversion technology, which use MOSFETs and a small converter transformer to simulate an output transformer but without the frequency and distortion limitations of transformers. Like a transformer, the circuit is a two-way impedance converter, in which the impedance of the load (headphones or speakers) is reflected back to the output tube (multiplied by the conversion ratio), and the tube's plate curves are reflected to the speaker (also changed by the same ratio).
post #9 of 16
Thread Starter 
Is this the teal color?
post #10 of 16
(oops beaten to it)

but yeah it isn't true OTL...
post #11 of 16
Thread Starter 
Teal or no teal that's the question...
post #12 of 16
I think this would be the teal:


post #13 of 16
what does the "Z" in ZOTL stand for?

maybe it's a descendant of the mythical Zeus! please post info!
post #14 of 16
guys...stop posting pics of that amp! I'm getting shorts in my comp!

post #15 of 16
Thread Starter 
evilchtul: oh thanks. I thought teal would be more "greenish"...
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