Aikido and K-1000 headphones?

[Thunau]

I saw that many different tubes can be used with the Aikido and one of the applications is headphone amplifier. I own AKG K-1000 headphones. The K-1000 has impedance of 120Ohm and low efficiency. It calls for about 1W of power to drive it to full output. My calculations come up with roughly 11V and 0.01A needed to drive the headphones. Are there tubes in existence that would work in the Aikido and provide enough output to drive the AKG K-1000 headphones?

[Alain Dupont]

Thunau,

with

http://www.tubecad.com/2006/09/24/ai...0amplifier.png

using a first stage with 6CG7 gives 10 of gain
so for 1 volt imput gives you 10 volts output, right on target!

and the 6DJ8 would work well for lower impedance headphones...

http://www.tubecad.com/2006/09/18/Ai...%20A%20PCB.pdf

Look at the user guide about this .. in the typical values array
with 470 uF output cap

Regards.

Alain.

[Thunau]

Thanks,
Are these tubes capable of the needed current as well? I'm not sure how to read the spec sheets that I can find.

EDIT:

I made an error in my calculations. I would need 11V and 0.1A (not 0.01A as indicated in the first post).

[Alain Dupont]

Thunau,

The K-1000 requires 1000 mWatts for 104 dB

and basicaly is made to be driven by the output of the amplifier directly,
as said in the documentation.

So we need 2 watts out of the headphone amplifier.

In page 4 of the Aikido user manual John discusses about a modification of
the output satge for this problem of low loads. He modifies the output stage
in a White Cathode Follower

Why don't you send John a message, he would be glad to provide
a better answer.
You'll find his email address on the TubeCad site. {editor contact}

Regards.

Alain.

[DrDeville]

Actually, if you go to TubeCad and look through the list of blogs, there are a number of articles on Aikido headphone amplifiers that should answer your questions.

Because of the good buzz, I'm in the process of building the 6CG7 / GDJ8 Aikido-CathodeFollower headphone amp that John Broskie describes here. I wouldn't be surprised if it is just what you need.

Of course, now that I have bought my Aikido boards, they're on sale. But I don't mind because they were a freaking steal at the price I paid.

[Alain Dupont]

Thunau,


And found on diverse articles floating around:
Forget using a headphone amp with the K1000, it needs a real, 2-channel, stereo-power amplifier. These headphones don’t plug into a regular headphone jack. They’re also very inefficient, consuming watts of power, as opposed to a few mill watts for all others.


Someone already did a good amplifier for the AKG K-1000

http://www.pmillett.com/ecc99_srpp_headphone_amp.htm

And specially for You...
http://www.jj-electronic.sk//pdf/ECC99.pdf

60mA 400V and 5 watts
Right on target for 2 clean output watts in John Broskie Aikido...
6.3 or 12.6 heater Noval socket

And a 12AU7 input tube... wow!!

I hope with this 2 you will find your design...

Alain.

[DrDeville]

Originally posted by Alain Dupont


Forget using a headphone amp with the K1000

And specially for You...

[edit: link to ECC99 specs]

60mA 400V and 5 watts
Right on target for 2 clean output watts in John Broskie Aikido...
6.3 or 12.6 heater Noval socket

And a 12AU7 input tube... wow!!

I hope with this 2 you will find your design...

Alain.

To clear up any possible confusion--here's a link to John Broskie's article on an Akido Headphone Amp that uses the ECC99.