need basic custom headphone mixer/amp advice

[oshunANDurth]

This is my first project so I need the most basic of basic instructions please. I've seen a couple of posts about projects with similar, but not exact specs, so maybe I've just got to modify one of them.


I'm looking to build a headphone mixer with the following necessary specs:

• 2 x 3.5mm headphone outputs with separate volume adjustment knobs
• 1 x stereo 1/4" TRS input

If it's not too much more cost or too difficult, the following additions would be great:

• 1 x SPDIF inputs
• 3 or 4 headphone outputs

With regards to power supply I have no idea, so will need some help on that - can't see that on/off switch is necessary though.

I also live in Australia, so don't know if that affects anything.

Don't care if it's transistor or tube driven.

Any help greatly appreciated. I've no experience but I am a fast learner!

 

[sofaspud]

Requirements 1,2, and 4 are fairly easy. Someone (sorry I forget whom) here at DIYaudio was praising the TPA6120A2 headphone driver from TI, for example. Build a circuit for each output, with a buffer/distribution amp feeding them. If you want a discrete solid-state or tube circuit, understand that that will be more involved, and the end product will be considerably larger in size!. But your wants are general so there's lots of options. You didn't mention anything about the headphones you plan to use.
Adding SPDIF isn't recommended for the inexperienced. If it was me, I'd just buy a retail product and incorporate it in your signal path. There's no shame in doing that.
You'll have to better explain the mixer part. You only gave 1 necessary input.

 

[oshunANDurth]

Thanks.

I know there's stuff out there, I guess I just wanted to do it for fun and because it's not really urgent that I get one.

Basically I use a lexicon alpha to muck around and record songs on my pc. I have a mate who comes over every now and then who I jam with but there is only one phone output on the alpha and when I plug a set of phones into the line outs there is a significant volume difference (lower) and the sound quality is diminished.

I just wanted to make a device that I could input into from the alpha and then plug in two sets of phones that I could manipulate the levels on separately. The Alpha also has SPDIF outs, so that's why I wanted those inputs.

I have sony MDR-201 headphones and Sharp HP-300 phones.

Pls ignore the mixer part, I cut and paste this from an earlier question I'd written and forgot to delete that.

 

[oshunANDurth]

just realised i meant RCA not SPDIF!

 

[sofaspud]

Go ahead and dive into the sea of DIYaudio! The suggested op amp circuit isn't really difficult, it'll be fun, it'll sound good with your instruments, your jamming buddy will be impressed, you'll be impressed... the list goes on. It can probably be built with a generic PCB, too. Adding RCA inputs is simply a matter of installing those connectors instead of another. Wiring is virtually the same. And you can get help here all along the way.