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Author Topic: Bottlehead Orthodynamic headphone amplifier  (Read 6766 times)

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Offline HF9

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Bottlehead Orthodynamic headphone amplifier
« on: November 17, 2011, 05:09:22 AM »
I'm sure it's more-than-likely already been suggested, but I'm sure a great number of people would be interested in a Bottlehead headphone amp made for the specific needs of an Orthodynamic headphone, namely the Audeze LCD-2 (and now the LCD-3) and the HiFiMan series. I realize that there are already three headphone amps that Bottlehead offers, which is probably as saturated in the market as you'd like to get, but I feel that a specialized amp would really fill a specific niche that has not been satisfied yet. The most recommended amps for these headphones run into the several thousand dollar range; I'd imagine a solution in the $7-800 range would easily be viable in the market, and due to the popularity of these headphones, there shouldn't be any trouble selling them.

Has the Bottlehead team put any thought into an orthodynamic headphone amp, or perhaps a modification to an existing design (like the Smack) to better suit these headphones?
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Offline Doc B.

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Re: Bottlehead Orthodynamic headphone amplifier
« Reply #1 on: November 17, 2011, 05:31:33 AM »
The new S.E.X. 2.1 wired for 32 ohms output was found to work very well with the LCD-2s at RMAF, and I think the Paramounts would be the ultimate.
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Offline Paul Joppa

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Re: Bottlehead Orthodynamic headphone amplifier
« Reply #2 on: November 17, 2011, 07:06:56 AM »
They do not seem to be that inefficient. Audeze says 91dB at 1mV, 60 ohms impedance. That means 12.5mW would produce 102dB in each ear, which is usually loud enough for most audiophiles - it's about the same as a THX-certified movie theater. Even Crack, which is not optimized for a low impedance, can produce more than that; Smack can make 200mW, and SEX 2.1 can make 1000mW.

I found a reference to "listening at 106dB with 15dB headroom" on a headwize forum. Frankly, I think this is ridiculous. The 15dB headroom is reasonable relative to nominal levels, but almost all recording engineers listed at 80-85dB nominal. Permanent hearing damage begins at around 85dB; OSHA regulations limit industrial noise at 90dB, which for most people means they won't lost the ability to understand speech until they hit 65 - that means no hearing above 3kHz, roughly.
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Offline HF9

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Re: Bottlehead Orthodynamic headphone amplifier
« Reply #3 on: November 17, 2011, 10:33:50 AM »
Lots of good information in this thread, thanks for the responses! How does the output on the S.E.X. 2.0 compare with the 2.1? Is there a way to wire the 2.0 for a 32ohm output?
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Offline Doc B.

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Re: Bottlehead Orthodynamic headphone amplifier
« Reply #4 on: November 17, 2011, 10:51:10 AM »
An update kit that installs the OT-2 output transformers from the 2.1 version into the earlier version will be available soon. It's on the list with about 3 other upgrade kits, that we hope to have done before Xmas.
Dan "Doc B." Schmalle
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Offline HF9

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Re: Bottlehead Orthodynamic headphone amplifier
« Reply #5 on: November 18, 2011, 05:34:41 AM »
Will that kit work with the Magnequest xformers?
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Offline Doc B.

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Re: Bottlehead Orthodynamic headphone amplifier
« Reply #6 on: November 18, 2011, 05:49:29 AM »
The upgrade kit will simply be a pair of OT-2s.
Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.

Offline Grainger49

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Re: Bottlehead Orthodynamic headphone amplifier
« Reply #7 on: November 18, 2011, 08:47:50 AM »
There are no less than three dedicated headphone amplifiers from Bottlehead plus a modification of the Quickie and Paramount for driving headsets.  There are only 3 amplifiers from Bottlehead capable of driving speakers.  

Maybe we are getting off kilter here?

If you need an amplifier for a given headset I feel certain there is already one out there that will either match with no mods or one that will make beautiful music with a slight modification.

Sorry, I don't listen to headsets!  Music is a physical experience to me.

« Last Edit: November 19, 2011, 08:43:14 AM by Grainger49 »

Offline porcupunctis

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Re: Bottlehead Orthodynamic headphone amplifier
« Reply #8 on: November 18, 2011, 05:38:04 PM »
I'm with Grainger.  I would prefer more preamp and power amp options.  I bought the Crack because of the sale and because I just enjoy building things and experimenting.  I don't think I will ever make headphones my main system.  My listening room is my sanctuary and I've always preferred to listen that way.

Randall Massey
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Offline HF9

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Re: Bottlehead Orthodynamic headphone amplifier
« Reply #9 on: November 18, 2011, 06:44:30 PM »
Maybe we are getting off kilter here?
Grainger, just because the idea may not be agreeable to you personally doesn't mean there isn't a good business case for a high-wattage Bottlehead amplifier for orthodynamic cans. I respect your opinion and enjoy your posts here on Bottlehead, but I don't really see the need for you to come in here and step on my feet for making a suggestion, even if it is one that isn't followed up on.
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Offline Grainger49

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Re: Bottlehead Orthodynamic headphone amplifier
« Reply #10 on: November 19, 2011, 04:09:34 AM »
That's right, I don't know how many guys out there prefer headsets to speakers.

But...  my point that there is already a Bottlehead amplifier to drive any headset out there is probably true too.  Possibly I have missed part of the point of the thread.

Offline Paul Joppa

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Re: Bottlehead Orthodynamic headphone amplifier
« Reply #11 on: November 19, 2011, 06:17:58 AM »
...
Has the Bottlehead team put any thought into an orthodynamic headphone amp, or perhaps a modification to an existing design (like the Smack) to better suit these headphones?
Looking over this thread, it strikes me that nobody has answered the original question directly yet. We are an excitable bunch!

To address that original question, I can say that we have indeed put a lot of thought into these (and other) lower-sensitivity headphones. Seems like every time I went over the Bottleheadquarters in the past year or two, the subject has come up; in fact it was one of the considerations that went into the Smack design, which could otherwise have gotten away with a much lower output capability, and possibly used the much smaller PT-1 power transformer at a lower price point. I don't know if there will be any LCD-2 or -3 'phones at the meet today, but I am very interested in what people hear. The higher-power option would be the SEX, but it is less refined, having two stages and no shunt regulator. Still, it was apparently well recieved with LCD-2s at RMAF. When the OT-2 output transformer kit is finished (it has a 32 ohm option) the OT-3 could be used instead giving 16-32-64-128 ohm choices.

The other headphone idea that keeps coming up is an OTL design for electrostatic phones. So far there do not seem to be enough of them on the market to make it worthwhile, and of course the design and safety challenges are substantial. But the subject never goes away completely.

As for amps and preamps, of course you all know we are working on a new DHT OTL preamp. We do keep butting our heads against the wall searching for a reasonable way to get 15 watts. No success yet.
Paul Joppa

Offline HF9

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Re: Bottlehead Orthodynamic headphone amplifier
« Reply #12 on: November 19, 2011, 08:21:41 AM »
My apologies, I was being a little excitable yesterday. I appreciate the direct response on this Paul. I've been listening to the LCD-2s with the S.E.X. which is a very good combination, but I feel that there could potentially be a better pairing for them.

Paul have you looked into the reproduction ST-35 iron? The two Z-565 outputs and PA 774 power transformer run ~$210 and would produce 17.5W. It might be neat to see a high-end design built around them.
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Offline Paul Joppa

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Re: Bottlehead Orthodynamic headphone amplifier
« Reply #13 on: November 19, 2011, 03:51:03 PM »
Push-pull 6BQ5s do make an exceptionally nice amp, but they are not single ended, not triodes, and not without feedback. I have a pair myself, Heathkit UA-1s, which are very sweet but I never listen to them - I just like SETs better.  :^)
Paul Joppa