Simple balanced pad in patchbay

[salomonander]

Hey there,
a friend wants me to build a pad into his patchbay. Im wondering which kind would be the most universal in terms of impedance matching. Most of his gear is bridging, but he has some 600ohms pieces as well. Should i go for an H-pad or a bridged H-pad. Also, which impedance should i apply?

Thanks!

 

[emrr]

The only 'universal' thing will be 'U' pad in my view. Bridging in, low Z to receiver. That's what you see historically when dealing with unknown source Z's, which generally will be strapped with a resistance already if one is required (which makes it an 'O' pad), especially these days. The actual problem is....how much attenuation?

 

[salomonander]

Thanks! He wants a -10dB pad.
Is anyone maybe smart enough to do the math for me? I cant find any calculators for u-pads and im terrible at any kind of math
It should be bridging in, low z out and -10db. Thanks!

 

[emrr]

Many of the old broadcast catalogs online have pad charts in the appendix

 

[salomonander]

I did find a calculator. I do not totally understand the L/U-type matching checkbox though. Should i go for Z1 - as in match to 10k?

I attached both options. Does this look about right? Which matching type should i choose?

Here is a link to the calculator:
https://k7mem.com/Res_Attenuator.html

 

[emrr]

Z2. Put different values in and see what changes.

I put 200 source 600 load.

That presents somewhat less than 2200Ω to the source assuming actual 10K receiving Z.

If you put 1K load, the values all go up making a lighter source load of roughly 3K5-3K6.

Examine those trends. Notice you can change the source Z value and it doesn't affect the R values at all.

The actual easiest method is to play with some actual resistors, measure the loss. It's a simple voltage divider.