diyAudio

diyAudio (http://www.diyaudio.com/forums/)
-   Tubes / Valves (http://www.diyaudio.com/forums/tubes-valves/)
-   -   Headphone output (http://www.diyaudio.com/forums/tubes-valves/220786-headphone-output.html)

Edwar65 1st October 2012 12:29 PM

Headphone output
 
Hi, being a relative newcomer to valve amps, I have a mengyue mini valve amp of about 12w per channel that I would like to add a headphone output to ideally via a separate jack that would isolate the speakers when plugged in.
I'm reasonably competent at electronics, can someone explain the easiest way to accomplish this. I'm using a set of Grado sr80 headphones, I'm unsure of the impedance of these?
Any help much appreciated,
Tom

disco 1st October 2012 04:36 PM

32 ohms. If you'd live near I could trade you a set of 5W output transformers (1:24). That would be a simple solution ;)

alexmoose 1st October 2012 09:27 PM

I did this once with an EL84 SET amplifier. The approach I took was to put a resistor in parallel with the headphones on the secondary of the OPT. This gives the output stage an 8ohm load.

for 32 ohms, a 12 ohm resistor or something close to that should be just fine.

don't blow out your ears...

Edwar65 2nd October 2012 09:33 PM

hi all, as I said, ideally would like to mute main speakers when plugged into amp via jack,would have to drill chassis to fix in jack for h/phones. As i've no experience of doing this a drawing may be the best idea if anyone could help,i can supply a photo of amp internals if needed?
many thanks for any help,
tom.

MrCurwen 3rd October 2012 01:22 PM

I usually wire my amps so that the headphone jack is always on, and the speakers are turned on or off by a small switch next to the speaker terminals. Works for me.

bayermar 4th October 2012 01:53 PM

Quote:

Originally Posted by alexmoose (Post 3186691)
The approach I took was to put a resistor in parallel with the headphones on the secondary of the OPT. This gives the output stage an 8ohm load...don't blow out your ears...

Maybe an voltage divider made by two resistors to reduce the level going to the headphones might be an additional improvement. This could be adjusted the way that the headphones have subjectively the same listening level as your speakers in use.
That way, one would not accidentally start with a deafening volume setting.
:2c:
Cheers,
Martin


All times are GMT. The time now is 04:05 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio


Content Relevant URLs by vBSEO 3.3.2