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[Michael Holmes]

(Sorry for posting under a pseudonym, no harm intended!  I didn't see the message about this at the top of the page.)

So anyways...

I have a need to run the output of a small mixer into a mic input of our installed mixer.  Unfortunately the small mixer doesn't have a mic-level output, but I have an Astatic LT-6 line matching transformer and I'm wondering if I can use it to match the line-level output of the mixer to the mic level needed by the installed mixer.  The transformer was originally intended for just the opposite -- i.e. to allow you to plug a low-impedance mic into a high-impedance input.

The small mixer is a Mackie 1202 (not the 1202 VLZ, but the earlier version).  The installed mixer is a Peavey Media Matrix.  The Peavey does provide phantom power to the mic jacks, and we need to leave phantom power turned on.

I tried using this transformer to plug my strat into a low-Z mic input (without phantom power), and it worked just fine.  Would this also work for the line-level output of the Mackie mixer?


Thanks!

Mike

[Scott Helmke]

Should work.  I don't think you can cause any damage trying, anyway.

[Riley Casey]

If it is in fact a mic level transformer the worst that will happen is that you will over saturate the transformer by driving it with a line level rather than a high impedance mic level.  Keep the ouptut of the mixer at about -20 if you get distortion and make up the difference with the venue mixer.

I have a need to run the output of a small mixer into a mic input of our installed mixer.  Unfortunately the small mixer doesn't have a mic-level output, but I have an Astatic LT-6 line matching transformer and I'm wondering if I can use it to match the line-level output of the mixer to the mic level needed by the installed mixer.  The transformer was originally intended for just the opposite -- i.e. to allow you to plug a low-impedance mic into a high-impedance input.

[Greg_Cameron]

I have a need to run the output of a small mixer into a mic input of our installed mixer.

Use a DI with the RCA output of the mixer. This is no different than any other application where you need to step a line level down to mic levels where you might also need total transformer/ground isolation. You can use the 1/4" output into the DI on the MS1202 only if you have a custom TRS to TS cable into the DI where the sleeve on the mixer side is left unconnected. The old 1202 has active balanced 1/4" outputs and a topology that doesn't like to have the cold shorted to ground.

[Michael Holmes]

Thanks to everyone for the advice and tips!  I tried it and it does work, but unfortunately the transformer is picking up enough hum that it's really not acceptable.  I'll need to use a decent quality DI box for this application.  Thanks again,

Mike

[Mike Pyle]

Thanks to everyone for the advice and tips!  I tried it and it does work, but unfortunately the transformer is picking up enough hum that it's really not acceptable.  I'll need to use a decent quality DI box for this application.  Thanks again,

Mike

The hum is likely a ground loop. Do you have the two mixers plugged in to the same a/c circuit? If not, you may need a ground lift on whatever DI or isolator you use.

[Michael Holmes]

The hum is likely a ground loop. Do you have the two mixers plugged in to the same a/c circuit? If not, you may need a ground lift on whatever DI or isolator you use.

I don't think that's it.  When I tested, both mixers were plugged into the same circuit.  I think I know what the problem is: the transformer has dedicated cables attached to it, and they are flimsy cables that probably don't have great shielding.  I'm going to mount the transformer in a shielded box, get rid of the cheap cables and wire in a ground lift switch at the same time.

[Geoff Doane]

  I think I know what the problem is: the transformer has dedicated cables attached to it, and they are flimsy cables that probably don't have great shielding. 

Cable shielding is only for RF (MHz), not low frequency magnetic fields.  The steel case for the transformer may do the trick, or simply moving the transformer farther away from whatever is inducing the hum (wall warts typically spray magnetic fields around), will solve the problem.

GTD

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