pm1000 phantom problem

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buschfsu

Well-known member
Joined
Dec 31, 2004
Messages
760
Location
jacksonville FL
my pm1ks that ive racked sound great with an sm57. when i try to add phantom for a condensor i get alot of hum and no mic signal. i verified that there is 47volts at pin 2 and 3. im stumped. this circuit uses the primary center tap to distribute phantom to the mic. anyone else had this happen?

i tried the 57 with phantom (just to test it) and it sounds ok, its just with my condensors, and i verfied that they were ok with another preamp.
 
Is the 48V to the center tap with no 6.8k resistors?

Some microphone circuits need the 6.2ks a Schoeps circuit uses them as part of the circuit as emittter Rs.

If you are using circuits with schoeps type outputs you might have problems and other circuit might have problems.

What microphones are you trying?
 
mxl 1006 with cap upgrades. schoeps circuit i think. im at the point where im just going to take 48 off of the power supply and put some caps and 6.8k resistors and screw the whole transfo thing.

what do you think.
 
I could swear I've answered this exact question in the last couple of days... did you cross-post it anywhere?

Anyway, my response was that the PM1000 is kind of goofy as far as grounding goes. Make sure you've actually got a ground connection all the way from the power supply to the mic input XLR.
 
yep, cross posted at tapeop, thanks for the tip ill check the ground path, i have the psu and the board ground attached to the chasis. i don't think th e xlr is connected to the same ground point, just the chasis and the 1 pin is connected to the red wires shield.

thanks for helping man, i am really happy with this pre. your posts and tubejays helped alot.
 
ok heres the solution thank to scodiddly,

the red wire connected to xlr input has +, -, and screen i connected to 2 3 and 1 but 1 also requires a connection to the common chassis ground that the psu and everything else is grounded to. once that was made it made phantom work correctly and any noise in the pre was gone.

thanks!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
ok last step....

i want to hook up the DI's and most people use normalling jacks. I only have 1/4" TRS non-normalling jacks. should i switch the DI into the circuit or is there another way?
 
spend an extra $2 and buy a normalling (i.e., "switched") TS jack. I think even Radio shaft carries them. it's proven to work.
 

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