Hi Riga,
there was a thread just a few days ago about an highend headphone amplifier on diyaudio
--> http://www.diyaudio.com/forums/showthread.php?s=&threadid=134603 .
Though this one uses different output transformers at a different ratio.
You could also ask dsavitsk who responded on this thread and has MANY headphone amps on his site (transformer coupled).
there was a thread just a few days ago about an highend headphone amplifier on diyaudio
--> http://www.diyaudio.com/forums/showthread.php?s=&threadid=134603 .
Though this one uses different output transformers at a different ratio.
You could also ask dsavitsk who responded on this thread and has MANY headphone amps on his site (transformer coupled).
Because these transformers are 20K:150, you will want to use headphones with a high impedance, relatively speaking. You are right in between several, as Audio Technica seem to be in the 80 ohm range, while Sennheiser, Beyer Dynamic, and a few others are in the 300 ohm range. For the Sennheisers, you can run these 10K:300. I would think that either can be made to work with the right tube. Grados, at 32 ohm, are likely too low Z.
However, the difference in sound (not to mention comfort) between different phones is much larger than between different transformers or amp designs. I think I would pick the headphones you like, then pick the amp to go with them. And, indeed, while I like transformer coupling for low impedance headphones, for the high impedance designs, it may not be necessary, or even desirable.
However, the difference in sound (not to mention comfort) between different phones is much larger than between different transformers or amp designs. I think I would pick the headphones you like, then pick the amp to go with them. And, indeed, while I like transformer coupling for low impedance headphones, for the high impedance designs, it may not be necessary, or even desirable.
The max input power into my AKG K 701's impedance of 62 ohms is 200 mW, which works out to roughly 3.5 volts RMS. At the rated 105 dB for 1 mW that's 128 dB at the ear. Headphones are insanely efficient.
The same max voltage at the output of a regular tube OPT is less than 2 watts into 8 ohms.
The same max voltage at the output of a regular tube OPT is less than 2 watts into 8 ohms.
I use Sennheiser 580s which are similar to your 600s. I find that all CD players with a headphone jack have enough drive for them to play louder then I should ever use. Even my cheap 32 ohm phones play loud from them. Lacking any headphone output, only modest amplification is necessary from line level.
JoshK said:
Indeed, many HP amp have too much output to be truly safe for ones ears. But it's more then that. Most all players that provide a headphone output feed it from a SS large scale intergrated circuit. These LSICs probably don't have the best quality sound. So a small external tube HP amp driven from the line output is a nice thing to listen through as well as being fun to build. It should be more about fidelity then power.
HollowState said:
The higher the impedance of the headphones, the more voltage you need.
JoshK said:
Most people who have tried unity gain amps for high impedance phones have found that there is something lacking. These phones do seem to need a little gain.
I did some measurements on what Grado (32 ohm) headphones need in terms of voltage which can be found at http://www.ecp.cc/less-pressivo-plus-plus.html
I made a simple headphone amp for my Sennheiser 580s using the Magnequest B7-15K transformer. I would think that any 15k:600 would work fine for these 'phones.
I like the combination enough to have spent many hours listening to them. I also have a couple of chip amps I use when traveling and I prefer the tube amp.
I like the combination enough to have spent many hours listening to them. I also have a couple of chip amps I use when traveling and I prefer the tube amp.
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Osprey said:I made a simple headphone amp for my Sennheiser 580s using the Magnequest B7-15K transformer. I would think that any 15k:600 would work fine for these 'phones.
I like the combination enough to have spent many hours listening to them. I also have a couple of chip amps I use when traveling and I prefer the tube amp.
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