I need to make this. I don't know how...

[pixeltarian]

I have an echo MIA midi with L/R balanced outputs.

I want to make a box that takes them and adds a headphone option with volume control. also a stereo gain for the monitors would be nice. They're active monitors though so I don't know if that's a problem or not. nothing more. nothing fancy. NOT a mackie big knob or other dumb things. I just want to add a headphone jack to the ECHO MIAmidi. I figure I'd rather spend the money on just what I need and make it very nice with high quality stepped attenuators and such.

so... do I need to integrate a low noise headphone amp into the box? It's for studio monitoring so I don't want to jeopardize quality monitoring. so here's visually what I want to do because I'm not ultra good at explaining things with words:

[jaycee]

You could probably do what you want with any headphone amplifier and a set of Y cables.

[lineup]

you midi unit
have balanced outputs

you need to build one UNIT BOX
with balanced input.

Easiest way to do this is to use one Balanced Receiver IC.
Which output 'normal' unbalanced RCA signals.

After this IC you can put one HeadPhone Amplifier
putting out a few Watts only.
There are even IC Power Amplifiers for this .. around like 1-5 Watt output.
( see the Chip Amps forum )
Such an headphone amplifier would be able to drive a pair of small monitor speakers, too.
Besides your headphones.


Alternatively you could have one special RCA stereo output
(after the balanced to unbalanced IC)
that would drive a pair of PC-speakers .. with built in Power Amp.
You know those we put beside our PC-Monitors.
But even in this case you will need one separate Headphone amp.
Even if some of those PC-speakers units also have one jack for a pair of Phones!

[lineup]

this is one of the most used
Differential Line Receiver which takes balanced input
(for example from Microphones or other XLR Connector Music equipments)
and outputs one normal un-balanced RCA signal

SSM2141 Balanced Receiver IC, Datasheet
you need 2 .. one for left and one for right channel

[pixeltarian]

thanks for the input guys!

Originally posted by lineup
this is one of the most used
Differential Line Receiver which takes balanced input
(for example from Microphones or other XLR Connector Music equipments)
and outputs one normal un-balanced RCA signal

SSM2141 Balanced Receiver IC, Datasheet
you need 2 .. one for left and one for right channel

cool. does it matter that each of the two channels coming from the audio card are balanced? are sure I wouldn't need 3 SSM2141 chips? otherwise wouldn't I have to convert the line from Dual TRS (used as dual balanced outputs) to just one stereo out and split the ground wire to go to each jack? with just two chips I'd be taking 6 wires in and three wires out for each differential line reciever. this is ok for the headphones because they're just stereo, not dual TRS. Is that ok for the monitors though, which are 3 each wires (balanced)? the monitors accept either 1/4 balanced or XLR. it's one of those neutrik combo jacks.

so converting it to RCA isn't the best idea. It still has to be balanced on 2 of the 4 output channels. all jacks need to be XLR or TRS and 1/4" for the headphone. actually I don't think it would matter to have two headphone jacks would it? one 1/8th inch and one 1/4 inch? would that work? or would I need to use an A/B toggle switch so the feed isn't getting wasted on a jack that's not in use?

[pixeltarian]

Alternatively you could have one special RCA stereo output
(after the balanced to unbalanced IC)
that would drive a pair of PC-speakers .. with built in Power Amp.
You know those we put beside our PC-Monitors.
But even in this case you will need one separate Headphone amp.
Even if some of those PC-speakers units also have one jack for a pair of Phones! [/B]

that sounds pretty good.

I guess I should mention that my monitors are 5" tannoy reveal 5a monitors for pro audio recording. this project is for my home recording studio setup. The balanced to unbalanced IC would work for the headphones, but I would need dual balanced to balanced for the monitors.