DIY rackmount rotary DJ mixer

[efinque]

Sup GDIY,

this is my latest project which I started yesterday.

Here are the parts:

Here's the back panel:

Here's the input section done with PFL:

Then the master EQ pots:

Here's the front panel as of now:

I've yet to add master out, master vol and headphone amp/output jack.

I'll post a schematic once I'm done.

Any thoughts/ideas?

-ef

 

[ruffrecords]

Is that a plastic 19inch rack mounting enclosure? Never seen one of those before.

Cheers

Ian

 

[efinque]

Is that a plastic 19inch rack mounting enclosure? Never seen one of those before.

Cheers

Ian

Yeah it's from RND Components. It's got ventilation on the sides, not that there's that many active parts inside.

The stereo channels are all passive. It's got a Kemo M040N preamplifier in the mic channel and I'll try to hook up an either NE5534 (IC) or BC547 (transistor) headphone amp.

I have one BC547 module on the shelf but iirc it required a pot to ground for volume control.

I'm thinking master preamps too. Those NE5534 modules are a PITA to assemble in quantities.

 

[efinque]

Here's the headphone amp assembled:

Decided to bite the bullet and go for the NE5534 route.

 

[C.B. - Boudio]

How about the shielding?

 

[efinque]

How about the shielding?

I've been mentioned of this before but I don't fully grasp the concept.

What people really wanted was balanced outputs. I've tried to build them using transformers but had no luck.

I just finished the unit. Looks great IMO, sounds ok too.

 

[C.B. - Boudio]

I've been mentioned of this before but I don't fully grasp the concept.

It's common practice to ground metal enclosures (or have a conductive layer of some sorts, in your case), in order to insulate the whole from electrical interference, notably where there is high gain (f.e. mic inputs) and the wires inside can act as antennas to pick up noise and such.
It could be that you get away with it, since you're using that preassembled opamp module, which may already be shielded on its inside (but I've never seen such things in person, so I don't know).
I'm no expert at all of course, quite the opposite, and other people will probably explain all of this better.
I think I'll experiment a bit myself with those Kemo modules, they look like very fun material for any small project.

 

[efinque]

It's common practice to ground metal enclosures (or have a conductive layer of some sorts, in your case), in order to insulate the whole from electrical interference, notably where there is high gain (f.e. mic inputs) and the wires inside can act as antennas to pick up noise and such.
It could be that you get away with it, since you're using that preassembled opamp module, which may already be shielded on its inside (but I've never seen such things in person, so I don't know).
I'm no expert at all of course, quite the opposite, and other people will probably explain all of this better.
I think I'll experiment a bit myself with those Kemo modules, they look like very fun material for any small project.

I see. They do this in electric guitars don't they?

Those Kemo modules are a tad expensive. And they distort the sound.

Here's the mixer paired with a 3-band crossover I did earlier this year :