Daven attenuator wiring

[pH]

I've got a couple of Daven 600/600 ohm ladder attenuators I want to wire to the output of my Federal compressor and my new MILA. I've never wired one of these and am a little confused. There are six contacts, looking at it on its side:

IN C OUT
IN C OUT

I looked at how Electrical Audio is wiring theirs in the Ampex 351 mod and they only use three points:

top side: transformer+ to IN / OUT to XLR pin 2
bottom side: transformer- to C to XLR pin3

This looks like it's unbalanced, yes? Is this how I should wire it? Also, do I terminate this with a 600R resistor like they do?


Cheers,
Paul

 

[emrr]

It works in a balanced line that way. No reason to terminate a ladder; the impedance is fixed (self terminating). Put a multimeter on the out / common connection and have a look. You do need to terminate T and H attenuators.

 

[pH]

Thanks for your reply Doug.

If I take readings on just the left set of contacts I get a constant ~640R between COM and OUT, variable from 310R to 950R between IN and OUT and IN and COM.

On the other side I get no readings at all between any of the contacts on either side.

So it looks like I only use the left side of contacts?

 

[emrr]

[quote author="pH"]So it looks like I only use the left side of contacts?[/quote]

Sounds like it. Usually there is connection, but sometimes not. they can be jumpered if you needed more contact area, for sure. Your measurements sound right, to memory.