monitor control

yan_b · Jun 10, 2004

hi every one
this is my first post in the forum, i've read some post on monitors control back in the old tt , but didn't find a post on this exact subject.

what i would like to build is a monitors switching device, the one that you can find on every big recording console, but that would switch before and after the power amp.
This way i would be able to use one amp for a number of speakers.
Now the tricky part for me is the gain matching for the speakers in the preamp stage.
What i thought to do is, by using relays in the feed back path of the master gain knob
That will switch to diffrent pot's for adjusting the gain for each pair of speakers.
I would like to hear your's thought's on this kind of design , or if some one tried it before, and some advice about what opamp should i use for the master gain section.

great forum btw. :thumb:

Guest · Jun 10, 2004

Here's a good start: http://www.goldpt.com/diy.html See Schematic: Passive Line Stage and Schematic: Full Featured Mode Switch

Every thing you need for a good simple passive monitor controller.

Cheers,

elco
:shock:

mcs · Jun 10, 2004

If I understand you correctly you could use something like this: http://stiftsbogtrykkeriet.dk/~mcs/Remote5.jpg

It's a 5-input selector and 64 stage attenuator. You can save a level "difference" for each input. So you could use just the attenuator part to set the levels, and use the 5 relay drivers to switch speakers.

The attenuator is made using 6 small relays and 24 resistors (for two channels). You could also use a chip like the LM1972 if you don't like resistors and relays...

Best regards,

Mikkel C. Simonsen

clintrubber · Jun 10, 2004

from Mikkel:

You could also use a chip like the LM1972 if you don't like resistors and relays...

FWIW, this makes me realize that an IC we designed at work some years ago could come in handy here. It was a small BTL-amp with a volume control before it, so you get level & conversion to balanced together. Meant to drive a speaker, but THD cleans up nicely for less heavy loads.

But before the actual shameless plug & type-number is inserted let me check if there are other specs that make it perhaps unsuited for this application.

Regards,

Peter