With your outlook of only one designer you have limited your choices.
All of the standard Pass designs have too much gain (amplification) for your AKG K702 headphones.
Gricko provided a good recommendation: http://www.diyaudio.com/forums/headphones/22817-jwbs-ultimate-aleph-headphone-amp.html
My suggestions would be:
The Cavalli-Kan Kumisa III Stereo Headphone Amplifier
The SOHA II Headphone Amplifier
All of the standard Pass designs have too much gain (amplification) for your AKG K702 headphones.
Gricko provided a good recommendation: http://www.diyaudio.com/forums/headphones/22817-jwbs-ultimate-aleph-headphone-amp.html
My suggestions would be:
The Cavalli-Kan Kumisa III Stereo Headphone Amplifier
The SOHA II Headphone Amplifier
I don't want to sound self-advertising, but if you intend to use the AK702, you should IMHO give this a serious consideration:
http://www.diyaudio.com/forums/pass...urce-follower-configurations.html#post1603771
With 6x ohm impedance, you need lot of current and not much voltage; also essentially no need for voltage gain. The cascoded LU1014 in triode mode is really ideal for the task. The DAO gives a perfect square wave output at 67 ohm.
Patrick
http://www.diyaudio.com/forums/pass...urce-follower-configurations.html#post1603771
With 6x ohm impedance, you need lot of current and not much voltage; also essentially no need for voltage gain. The cascoded LU1014 in triode mode is really ideal for the task. The DAO gives a perfect square wave output at 67 ohm.
Patrick
Yes, that's the "problem". My amplifier could share (if properly alimented with 70 volts) 200 watts in AB1 class with normal loudspeakers. I obviously know that...
But with headphones it's a totally different matter: it's something that could be compared to a couple of very low efficiency loudspeakers with a very low impedance which need to set your amplifier volume on the maximum level ever: I don't like it and feeling that I'm near the amplifier limits ever when I use a high impedence headphones.
Because I'm not an engineer, but a person that really need to listen to music at high quality levels (and realistic volume), I thought that someone could have the same "problem" of mine and more experience about.
Thank you.
But with headphones it's a totally different matter: it's something that could be compared to a couple of very low efficiency loudspeakers with a very low impedance which need to set your amplifier volume on the maximum level ever: I don't like it and feeling that I'm near the amplifier limits ever when I use a high impedence headphones.
Because I'm not an engineer, but a person that really need to listen to music at high quality levels (and realistic volume), I thought that someone could have the same "problem" of mine and more experience about.
Thank you.
Usually the answer to that question would be "yes it's you", but in this rare case, no it's not you
He sure is using the headphone socket, but since when has reason had anything to do with it?
Magura
Risus abundat in ore stultorum...
By the way, I post my main circuit board If someone polite (perhaps in Italy we have a totally different conception of interpersonal behavior) would like to share and to argue about objective reproductions problems: if You don't feel some problems, it is a problem of yours, not of who have them.
Arturo Benedetti Michelangeli was just fool or a "science oriented" artist able to hear things as they were really?
Thank you very much indeed to all answer with praiseworthy intentions.
See you soon.
By the way, I post my main circuit board If someone polite (perhaps in Italy we have a totally different conception of interpersonal behavior) would like to share and to argue about objective reproductions problems: if You don't feel some problems, it is a problem of yours, not of who have them.
Arturo Benedetti Michelangeli was just fool or a "science oriented" artist able to hear things as they were really?
Thank you very much indeed to all answer with praiseworthy intentions.
See you soon.
Attachments
That's interesting finally!
Consider that it works with 40 volts actually in front of 70 volts for the 400 watts in 8 ohms (I don't need them obviously!).
It is possibile that the problem could be the pot: I'm using a temporary pot before finish the project in his case with an Alps 100K: I'll try to change it.
But it is more interesting the possible sensitivity problem: if it is too low for the headphone purpose (remember that this amplifier was projected for loudspeakers), what could I do?
Thank you sincerely
Which source do you use? How many millivolts it produces, at which impedance?
Dou you know the input impedance of your amp, its sensitivity?
All these need to match either you cannot feed properly your amp with the signal.
Have you hooked speakers to this amp, you should feel the same problem. If there is a mismatch this will not affect the headphones specially.
Dou you know the input impedance of your amp, its sensitivity?
All these need to match either you cannot feed properly your amp with the signal.
Have you hooked speakers to this amp, you should feel the same problem. If there is a mismatch this will not affect the headphones specially.
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Thank you, I see. Tomorrow I'll measure and I'll say the values.
By the way, I believe to remember (I checked it) that the amplifier input impedance is 500k ohms about.
The source I usually use are standard cd players, sometimes also a cheap portable player (I study music and I need to move from a room to another very often: i can't carry everything everytime).
I Thank you very much. See you soon.
The cd player I used for testing and for the first listenings to the amp is a 800.000 ohms output impedance (measured with really professional analog multimeter) and the amplifier near 500.000 ohms input.
Smells fish?
Now this was a weird thread. Maybe it should have just died here. On the other hand, I just couldn't resist
You see, I own a pair of AKG 702's (among several other equally good 'phones). And the 702's are happy with just about everything I throw at it. I've tried Grace, Musical Fidelity, Benchmark...... Too little level is never a problem! Connect it directly to a non-valve CD-player output, and it's LOUD! Way too LOUD!
So, since this is a site for people with some technical knowledge, here's the spec's for the 702:
Sensitivity: 105 dB/V
Rated impedance: 62 ohms
Max. input power: 200 mW
Now, if we combine these spec's, we'll find:
1. Max. input VOLTAGE = 11 volts
2. SPL at 11 volts = 126 dB
So - do you smell fish now? An amplifier putting out levels far above what the 'phones can handle -- and it's still not loud enough?
There have been some hints to the source of the "not loud enough" problem. Did the thread starter ever answer to them?
Now this was a weird thread. Maybe it should have just died here.
On the other hand, I just couldn't resist You see, I own a pair of AKG 702's (among several other equally good 'phones). And the 702's are happy with just about everything I throw at it. I've tried Grace, Musical Fidelity, Benchmark...... Too little level is never a problem! Connect it directly to a non-valve CD-player output, and it's LOUD! Way too LOUD!
So, since this is a site for people with some technical knowledge, here's the spec's for the 702:
Sensitivity: 105 dB/V
Rated impedance: 62 ohms
Max. input power: 200 mW
Now, if we combine these spec's, we'll find:
1. Max. input VOLTAGE = 11 volts
2. SPL at 11 volts = 126 dB
So - do you smell fish now? An amplifier putting out levels far above what the 'phones can handle -- and it's still not loud enough?
There have been some hints to the source of the "not loud enough" problem. Did the thread starter ever answer to them?
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