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i thought i would 'sample' the waters and try out a headphone amp that is O.T.L.-driven. - my intro or entry into this type of tube amp . . .
wondering if -
- it would this give me a *representation* of the O.T.L. sound (presuming tubes used to be 'standard' ones or the same as in a regular amp if compared side by side).
- heat: i'm afraid of heat issues and figure this would be a released in a minor way in a headphone amp.
lastly, does heat released ever interfere with the sound, somehow 'get in the way' of what one hears? (this would be more of a general question on the matter, i realize)
no brands yet, considering one made in Russia? (Hartung? price reasonable at $400 U.S.)
thanks for interest.
your board seems cool (!)
roger wang
Follow Ups:
For OTL's this is kinda pivotal. It seems that more headphones are designed with low impedances these days, like 32 ohms or less (yikes!), the easier to suck sound out of a wimpy SmartPhone op amp.
But if you want an OTL headphone amp, you're better off with a headphone with an impedance at least 150 ohms, and 300 ohms would be better. You want those tubes to operate more as a voltage source than a current source.
AnalogDog
Mozart and Beethoven are giants...who are standing on Haydns shoulders.
The Bottlehead Crack w/ the Speedball upgrade comes in at $391. As stated it deals with high impedance headphones beautifully. Mine is mated with Sennheiser 650 phones and I couldn't be happier. The heat of the big WE 6080 dual triode output tube is negligible. The 12AU7 is barely worth noting. After a few hours the power transformer will get mildly warm to the touch.
The heat noted as a general question may be worth a small stab... With enough tube amps running during a summer's night one may be tempted to kick on the AC and that will effect the sound! :)
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"- heat: i'm afraid of heat issues and figure this would be a released in a minor way in a headphone amp.lastly, does heat released ever interfere with the sound, somehow 'get in the way' of what one hears? (this would be more of a general question on the matter, i realize)"
Without heat, the tubes will not operate, so it is simply a necessity for operation.
It's pretty tough to speak to how much of the flavor of an OTL amp that you'll get out of an OTL headphone amp. Generally OTL speaker amps are considerably more complex (not necessarily in a bad way), as they have to deal with the bizarre impedance curves found in many hifi loudspeakers, and generally several output devices are required per channel to adequately drive a pair of loudspeakers. (Headphones are pretty well behaved in terms of impedance, and a strictly high impedance headphone amp can be built with one triode per channel)
Edits: 08/12/14
With all respect, any amplifier has to deal with "the bizarre impedance curves found in many hifi loudspeakers". Yes, OTLs generally require lots of output tubes in parallel in order to transfer adequate power into low impedance speakers. But the upstream circuitry is usually no more complex than that of any tube amplfier, and the elimination of the output transformer IMO lessens the complexity of the output stage compared to OTC amplifiers, apart from paralleling tubes.
Yeah, my point was that headphones as a whole are much more benign than loudspeakers as a whole, so an OTL headphone amp need not be as difficult to design as an OTL speaker amp.
Take a look at these
http://schiit.com/products/valhalla-2
Alan
Ideally what you'd want is a direct-drive relationship between an OTL amp and an ESL headphone, where the stators of the ESL are driven direct from the output tubes. I think there are some such products out there, for big bucks. Heat not an issue at all. Would probably sound "amazing". (Some times questionable grammar makes good sense.)
Woo Audio makes several very well-regarded headphone amplifiers, including at least two OTL versions. They sell Stax headphones also. The former vary in price, from the reasonable to the expensive; the latter are very expensive. I have an old pair of Stax headphones that are the ne plus ultra in my experience.
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Put the Bottlehead Crack on your list. It is $280, or $400 with the "Speedball" upgraded p/s. It is a kit, with superb assembly instructions. Tech support, via Bottlehead's forum, with its many serious DIYers who are always willing to help each other, is great. Support from the company via "Doc" Schmalle, is also outstanding. The amp is for high-impedance headphones, and, with the Senn HD800s, produces the best sound I've ever had in my system.I don't know how much heat it puts out, but there are just two tubes; a 6080 and a 12AU7. (Designing an OTL amp for a high-impedance load eliminates the need for many output tubes.) I'm not sure what you mean by vacuum tube heat "getting in the way" of the sound.
WW
"A man need merely light the filaments of his receiving set and the world's greatest artists will perform for him." Alfred N. Goldsmith, RCA, 1922
Edits: 08/11/14
favorite product was his OTL headphone amplifier. I never heard it, but those who did were enchanted by it. Imagine an OTL headphone amp driving ESL headphones. You might search for one in the NYC area.
I am not sure, but I think Ralph has whipped up an OTL headphone amp or two in his day.
Yes, in other words, it's a match made in heaven, since headphones tend to have very high input impedance compared to loudspeakers of any type.
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