[cmscott6]

This may be an elementary question, but maybe you folks can help.  

Does anyone run a pre-pre-out for a headphone amp from the GK-1?  My headphone amps don't require any pre-amplification, so I was wondering how to have a line output from the GK-1.  Can I wire from the selector switch to another switch controlling whether the chosen signal goes to headphone out or the GK-1 PCB?  Is this defiling or otherwise degrading the signal path?  Am I thinking too much?  

Thanks for any help!

[tropicalcb]

Just going on past experience with a couple of tubed preamps of around 1k out...and an old modded crown 150 pre, you can probably just plug a pair of 600ohm h/phones straight in. I have only ever used my beyerdynamic dt880's for this via 2x rca male into the preouts and the other end had a stereo female 1/4" socket for the stereo male on the end of the H/phone leads.....sonically it was a great match, particularly with an SRPP pre I had, but obviously there could be impedance considerations affecting the sonics...also the amount of grunt the GK-1 is capable of cranking out will effect what ends up in your ears.
....stereo male rca to female stereo 1/4" leads are cheap so it won't cost you much to find out. if it works the main benefit is you can leave out an extra stage of amplification and transport yourself directly into the recording booth....listening to kenny burrell and jimmy smith and other 50's/60's jazz via h/phones late at night (scotch, favorite chair, lights dimmed of course)...when the rest of the family is asleep, is one of my favorite RnR activities.....there's definitely a time-travel/intimacy thing with good H/phones and a good preamp directly into your head!!!!
    let us know how the GK-1 fares
cb

[AKSA]

Chris,

You can drive headphones of around 2K and higher, which is to say, very few.  The tube will handle a 2K load with reasonable grace, but lower impedances will require a buffer.  Low impedance loads will kick sand in the tube's face;  an unhappy situation I'm sure none of us would ever want to see.........    

Now, there is an argument raging on DIYaudio.com in the Solid State section under 'Borbely Fet Follower/Harry Haller' about how you do a sonically transparent buffer, but my own preference is for a White follower, a single ended design which Frank De Grove has published in the thread.  You will however need a very clean power supply and an output coupler, but you can in fact use the Auricap provided in the GK-1 and replace C21 with a 100nF quality cap like an RTX or PPMX.

I'm sorry to say this, but I'm not ready to do the necessary circuit tweaking yet;  give me a few months while I bed down a few other projects!      


Cheers,

Hugh

[tropicalcb]

Now that is interesting hugh...one of the main reasons I went with a slightly modified SRPP - almost identical to bruce rozenbilts version in GA about '91/92...is because it is/was so good at driving my dt880's from the original elektor SRPP preamp(also mainly because I have all the bits  - $$$$!!)....and the sound was just so right with the h/phones - maybe just a good match. I'm sure the oput impedance of that stage was around 1k2...maybe 2k??  ...which was also fine for driving any power amp I hooked it up to....and its got very few parts!!   I was looking fwd to a GK-1 down the track a bit...but because I use h/phones a lot, I will be checking out the white follower thread you mention as a mandatory addition.
 cheers...........cb

[cmscott6]

OK.  I have very low impedence Grado cans, so no way of running out of the GK-1.  

But due to impedence issues I can't bypass the GK-1 circuitry, by switching the input signal to the GK-1 board directly out to a pair of RCA's?  Is this correct?

In effect what I'm hoping to do is switch between three sources directly out to the headphone amp(s), without having to connect and disconnect interconnects from the GK-1 - whew.

And yes, the end result would hopefully be Miles and Coltrane blowing late at night with the lights dim and a glass of single malt close at hand  

Thanks folks.  I'll check out the thread you mentioned, Hugh!

[PSP]

Hugh will need to be the final arbiter of how suitable this approach is for the AKSA (with a good 4 pole DPDT switch to select Speakers or Headphones), but take a look at:  

http://java.audioasylum.com/cgi/m.pl?forum=tweaks&n=18995&highlight=headphone+amp+Jon+Risch&r=&session=

I have not tried this (yet) and it is so far down on my list of audio projects that I may never get there...

good luck,
Peter

[SamL]

Hi Hugh,

It is possible to use AKSA55 as headphone amp using the suggestion from this web site:

http://headwize2.powerpill.org/faqs.htm#amp

What if we lower the AKSA55 to 30w?


With great interest,
Sam

[AKSA]

Absolutely, Sam,

I can easily be done, and there are advantages since the headphone is much easier to drive, being primarily resistive, particularly if driven through a resistor anyway.

Exactly as Headwise suggest........

Cheers,

Hugh

[SamL]

Will get a AKSA55 once I finish my 100n.

Sam

[SamL]

Hugh will need to be the final arbiter of how suitable this approach is for the AKSA (with a good 4 pole DPDT switch to select Speakers or Headphones), but take a look at:  

http://java.audioasylum.com/cgi/m.pl?forum=tweaks&n=18995&highlight=headphone+amp+Jon+Risch&r=&session=

good luck,
Peter

Hi All,
I am looking for a headphone switch for a true mono aksa with separate power pcb. As I have not come across a 4PDT. Can I use it to switch the left channel, right channel, left earth and right earth all at the same time?

Edit: Can I use Michael Percy Audio TOCOS 4PDT as speaker out/headphone switch? It is rated as 6A/125V, 3A/250V.

TIA,
Sam

[AKSA]

Sam,

Your idea is sound;  this switch should do the job.  However, you will need to mix the left and right channels together if you wish to use mono.

Otherwise, if I misunderstand, you will need a separate amp for each channel, which will be taken off either the source L and R RCAs or the GK-1, as appropriate.

When you are ready to go ahead with the AKSA as a headphone amp, we will talk further.  There are further considerations I should discuss with you.

Cheers,

Hugh