Headphone amp bias help please

[firebirdV]

I mentioned before that I have a music amplifier for headphones (not for guitar) and that it runs on tubes. Well I think that the time has come to replace the quad of chinese tubes with some good NOS stuff, especially because they're pretty cheap. I have a schematic of one channel and I would like to know if I have to bias this.

 

[Jeff Seal]

Re: Headphone amp bias help please

...ya might wanna back up there, I lost you on the "replacing the quad" part.. I'll assume a rectifier perhaps??

regardless, the way the circuit is laid out ,final triodes are cathode biased, so the general answer to your question is "It should be just fine"..

Let me know where you're gonna find these "cheap enough"...

Jeff Seal

 

[the guy who invented fire]

Re: Headphone amp bias help please

I don't have an answer for this at all, and firebirdV, Im sorry for the hijack but I have to say whats up to Jeff! Good to see you brother! I've tried to get ahold of you a time or 2 with no luck...good to see you here again!

 

[firebirdV]

Re: Headphone amp bias help please

Thanks for the help, I wrote this in a bit of a rush so it probably wasn't too clear.
The amp uses some oddball tubes so the NOS tubes aren't too expensive (~$4 each), of course, I had to find the American equivalent to them first. The schematic shown is only for half of the amp, the other half is the other ear, so I need a quad of power tubes (the 2p3s).

I've found a few radio stores that sell the tubes as well as some ebay sellers. A lot of the ebay tubes look a bit old and corroded, so I think that I'll probably stick to the internet radio stores.

Again, thanks for the help, hopefully it will end up sounding a lot better.

 

[Artie]

Re: Headphone amp bias help please

I can't help with your question, but you may want to check out this forum/webpage. These folks really know their headphones and amps:

http://headwize.com/

 

[LJ King]

Re: Headphone amp bias help please

No you do not want to bias. The circuit is self bias but not only that it is an output transformerless design and the output tubes are set up as followers instead of common cathode used in transformer designs.