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I've settled on Audio Technica ATH-AD2000's as I find them extremely comfortable. With every amp I've tried them with, I am only able to use about 10% of the volume/attenuator dial.
I have only owned transformer-coupled amps having heard that they work best with low impedance headphones. Would an OTL design be a better match in this case? Should I look for a very low powered amp? Any insight is appreciated.
Amps tried so far (I prefer tube amps): Yamamoto, Trafomatic, Mapletree and Grommes.
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This is what makes the most sense to me. Just enough gain to drive the headphones as loud as you'll ever need to (but no more), and a very low output impedance.
I think there's more to it than that. First, there's the problem of dynamic range. The nature of amplifiers is such that the capability to flawlessly reproduce transient peaks without overloading necessitates more power than can be tolerated if it were applied as average input to the phones. This is evidenced by the fact that the best sounding systems always have an abundance of electrical headroom.
Second, it's been my experience that output Z isn't critical so long as the amplifier delivers sufficient power to overcome losses incurred in the matching network. To expound on this, it has never been proven to me that headphones benefit from an amplifier's damping factor. Therefore, I use resistive networks to ensure the amplifier sees a proper load. The same network can be designed to deliver the appropriate power to the phones from an amplifier that on the surface seems much larger than necessary.
Finally, I have never heard a solid state amplifier I could tolerate with headphones for more than half an hour or so. Even the best of them wear me down. This means - to my ears - only tube amps are suitable for this use.
I currently use a low power (4.5W/ch), Class A pentode amp for both speakers and phones. Each channel has a two-resistor matching network driving the headphone jack. This system produces an extremely articulate and lifelike listening experience, and it's superior to all but a tiny fraction of the $5,000+ systems I've heard in my life. To do this with low-end phones and a handful of amplifier parts truly amazes me. It's yet another reason I now work only with tubes. :)
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Buy Chinese. Bury freedom.
Did you reach a decision on this issue? I have something to add to the discussion, but the thread is five months old now. Have you found what you consider to be an optimum amplifier design for the new phones?
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Buy Chinese. Bury freedom.
I came across what i feel is a very nice amp, It is a single end EL84, although i doubt this is exactly what you are looking for. I think the amp he is building now would be exactly what you want
He is building a headphone amp based on the darling design that will output 3/4 watt. If you go to his web site and contact him Justin Weber (please tell him I suggested you contact him) He will give you the specifics. I can promise you that he is one of the nicest people in the business, and is passionate about his designs, build quality is second to none, fit and finish are superb
he is also very reasonably priced, I included a link to the site, Look under Products, Amps, Kenzie (the Kenzie now listed on the site is for speaker hookup, but he is building a dedicated headphone amp based on Kenzie)
Most OTL amps perform better into higher impedance loads.
What you would really want is a transformer coupled tube headphone amp with some padding at the input to get more range out of the volume control.
This is a simple modification (2 or 4 resistors) that can be added to nearly any amplifier.
Thanks for the suggestion. I floated that one to Lloyd at Mapletree, and he feels that doing so modifies the sound too much.
He suggested something similar be done at the output stage -- a short lead resistor in between the connections of the two transformers. He said that his amp has 7 ohms driving impedance, and to try a 100 ohm/1 watt, 1% quality resistor and see how that does. If it affects it too much then go to a 50 ohm one.
It got me questioning any modification so I wanted to get some other opinions. Please advise if you have any other thoughts.
Thanks!
Wow, I couldn't agree less with that suggestion!
Padding down the input does not change the sound character whatsoever. In fact, if one implemented a stepped attenuator, this could simply be done in the design of the control itself.
If you start putting series resistors at the output, you change the output impedance of the headphone amp, which changes the damping and distortion performance. You will absolutely hear this, it's not hard to measure, and it's very tedious to implement this and get it right. What's worse is that when you plug in a different set of headphones, you'll have to start all over. Frankly, this can make a Frankenstein mess with low resale value.
I've linked a page below that runs down how to adjust the range of a level control.
Also, if you have a transformer coupled headphone amp, you will generally have different impedance taps, and using the lowest impedance tap will reduce the sensitivity of the amplifier.
Thanks for the link. I've tried Rothwell 20db RCA attenuators, using them at the input. Is what you're suggesting a lot different from these?
http://www.rothwellaudioproducts.co.uk/html/attenuators.html
I would say that they helped a fair amount with the volume knob but also affected the sound. In an A/B comparison I preferred not using them. I'll read through your suggestion. But is there a different amp alternative that would avoid this modification?
That is the general idea, but you would get ideal performance by knowing the impedance that you're starting with (of the existing level control), then selecting your pair of resistors appropriately.
In order for an in-line RCA attenuator to work reliably, the resistors used will generally be lower values so that the following control impedance is less of a variable. This can result in some degradation (IMO).
If I had to guess, this pad would present an 11K load to your source, as opposed to your level control, which would likely be 47K-250K. (The manufacturer doesn't explicitly state impedance, but they do mention compatibility)
If you're getting an amp custom-made, just asked for a stepped attenuator whose range is 20dB below normal. If you already have an amp, you could just build such an attenuator and replace the existing level controls.
Thanks again CB! (I'd love to know the story on your handle :)
I will discuss this with Goldpoint and see what works best.
Best of luck on your search! Sometimes it's tough to avoid the audio hypochondria.
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