When building a pad to run line level through your pres. . .

[JW]

How many decibals would I normally pad if say I wanted to drive my UA 2108 properly on the way to the 2 track?

I havn't built a pad before but I've seen super easy schematics floating around.

Also, what are some quality parts to build it with?
Parts you'd feel comfortable running a whole mix though?
Mostly I know nothing about resistors. . . .

 

[Mark Burnley]

Well,

Assuming a 0dB signal path from the input of the pad to the output of the 2108, a -40dB pad would be suitable. So when the pad is applied to the mic input, and the 2108 gain is set to +40dB, overall gain input>output is 0dB. This would allow you to have a +/- gain trim as well, depending on how much you want to drive your machine.

Another way to look at it is to use a lower value input pad, of say -35dB or -30dB. This allows more saturation of the input transformer, which may, or may not be a good thing depending on yopur application.

Pads are cheap enough to make to allow you to experiment here until it sounds right. I use 1% metal film 0.6W resistors for pads. The 1% tolerance is plenty enough for channel-to-channel gain matching.

Let us know how it sounds!

EDIT- Just checked the manual, the Output Level control will give you the gain-marking on the Input Gain when set at "10". So it may be a case of adjusting the pad value, Input Gain, and Output Level until you get the levels of each stage sounding good for your program material.

Mark

 

[soundguy]

this might help-

http://www.tkk.fi/Misc/Electronics/circuits/line_to_mic.html

I would use metal film resistors. No need to get spendy, as you get into expensive resistors, most of the dough is for matching them to each otheer tolerance wise. You only need a few though, in which case its cheap enough to get real expensive resistors and see if you can hear a difference between the phoenix brand from digikey. I built an 1176 with holco resistors and black gate caps, turned out real clean, dont know how much of that was because of the resistors though.

dave

 

[Mark Burnley]

Rick Chinn's page is good for pad info too- check the table at the bottom of ready-to-go values for mic pads:

http://www.uneeda-audio.com/pads/

Mark

 

[JW]

Thanks guys,

Awesome info.