alesis ra150 as headphone amp

[river rat]

I have an alesis ra150 and would like to use it as a headphone amp. I also have access to a passive headphone distribution box. The dist. box has an xlr connector input. The alesis only has speaker-output posts. Any way to make this work?
Thanks...

[J M Fahey]

passive headphone distribution box.

Any links to it ?

[mozwell]

To Drive headphones directly from the RA150 speaker terminals, you will need to use a resistive divider to drop the voltage levels to the headphones.
Something similar is done on the Hughes & Kettner Vortex 80 amp.

I dont have a schematic for the RA150, but here is the RA500 information.

i woudl guess that hte distribution box with the XLR has pin 2 & pin 3 as left & right, with pin 1 as common. Maybe open it up to check, you can also check to see if there is a resistive divider.

So left (+) output from RA150 to XLR pin 2, right (+) output to RA150 to XLR pin 3, left or right (-) output to XLR pin 1

[J M Fahey]

*Now* I remember (slow brain/I'm a fool).
Short answer: those two equipment pieces are absolutely unrelated and AFAIK they are not meant to be used together at all.
There *is* a reason to the connector non-compatibility.
I work often in big shows (think 2500 seat Theaters to 50000 seat Stadiums) and I've used them, although I don't remember just now the trademark, but they are "the standard" out there.
It's an intercom system which links all pros working in that venue: main board operator, monitor board operator, lights operator, the ones who run those blinding very focused spotlights (we call them "caņones"="light cannons") which highlight the main singer o solo players, stage assistants, etc.
Radio is unreliable so this clever system uses one of the balanced microphone lines from the multi-way lines which run from stage to sound post so send voice back and forth, plus you can easily add more extension cables as needed.
There is no shortage of balanced mic cables at those venues.
This clever system also carries some signal which makes a very bright pilot light blink, as an attention getter.
Very useful, because in some places the sound level is beyond deafening, literally.
I guess what you have is an extension to add an auxiliary headphone.
It is not meant to pad a power amp's output into headphones, but to transmit the already headphone level signal that system uses.
Post the trademark and model, please.
Next time you watch an "Oscar night" and see those light cannon operators with headphones, you will be seeing this system in action.
A very clever idea.

[river rat]

Thanks for the interest and input. The headphone box is no longer available so I guess it's a moot point . Thanks again.