I set my prebee up without the xlr output. I am hoping to configure one of the inputs as xlr, for my DAC. I know that to get a true balanced input I need a transformer. Can I just copy the output configuration in the manual to the input and get reasonable results? Or would it be better to just direct wire the input without the caps and resistors, untill I get the transformer?
xlr/balanced Input
- Thread starter STURMJ
- Start date
Generally, you can wire the - pin to ground on the XLR jack if you'd like to use an XLR cable in an unbalanced configuration.
If you'd like to be the first one to install the balanced intput transformers, let us know and we can walk you through it.
-PB
If you'd like to be the first one to install the balanced intput transformers, let us know and we can walk you through it.
-PB
The Cinemag CMLI-15/15B is probably not a bad place to start, be sure to specify the single 3/8" stud for mounting.
The XLR jacks that you'll need will just be Neutrik D-shell jacks, Parts Express has reasonable prices on these.
Other than that, you'll want some extra resistance across the output of these transformers to load them properly (try 30K).
-PB
The XLR jacks that you'll need will just be Neutrik D-shell jacks, Parts Express has reasonable prices on these.
Other than that, you'll want some extra resistance across the output of these transformers to load them properly (try 30K).
-PB
The holes in the chassis are designed for a Cinemag, Jensen, and Sowter model. It actually never occurred to us to even include Hammond on the list.
While you could use the 10K Hammond, you would end up spending more money and drilling more holes in the chassis, with the disadvantage that there is no internal shield.
Also, having the transformer mounted through a single hole allows one to twist the transformer while you're listening to it, which should allow you to find the sweet spot where no magnetic hum is coupled (ymmv, this may or may not be an issue).
So, to use the Hammonds, you will need to poke all the wires through the hole in the chassis, twist the transformer around until it's quiet, mark the holes, uninstall the transformer, machine the holes, then reinstall.
For loading the secondary, I'd try a 12K resistor.
-PB
While you could use the 10K Hammond, you would end up spending more money and drilling more holes in the chassis, with the disadvantage that there is no internal shield.
Also, having the transformer mounted through a single hole allows one to twist the transformer while you're listening to it, which should allow you to find the sweet spot where no magnetic hum is coupled (ymmv, this may or may not be an issue).
So, to use the Hammonds, you will need to poke all the wires through the hole in the chassis, twist the transformer around until it's quiet, mark the holes, uninstall the transformer, machine the holes, then reinstall.
For loading the secondary, I'd try a 12K resistor.
-PB
You will need a pair of transformers.
-PB
-PB
I got the stuff! my only question is the load resistor you suggested. Does the 14k resistor go (I presume in serial) with the inbound wires, going in the transformer? Or on the wires coming out of it, or both. (my guess is the wires coming out of the trans. but I want to be sure)
Thanks again
Thanks again
STURMJ said:
Which transformers did you end up with?
I would put the load resistor on the secondary winding of each input transformer.
-PB
Excellent, you are beating us to the punch in terms of attempting this modification, keep us posted on how it goes.
-PB
-PB
Paul Joppa
Moderator
Load in parallel, not in series.
Looks good!
You can run a piece of clip lead from pin 1 to the little ground tab on the jack itself.
If the Hammond has a shield, the shield wire can be soldered to the ground lug on the XLR jack as well.
-PB
You can run a piece of clip lead from pin 1 to the little ground tab on the jack itself.
If the Hammond has a shield, the shield wire can be soldered to the ground lug on the XLR jack as well.
-PB
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