Using Pads

[soupking]

(And I'm not talking about Depends dammit

With API, Quad Eight, and other high gain preamps, it seems almost like a throw-in to have a pad for output.

I thought pads were used to bring the signal down, but as I've been reading, they seem to be an option to effect the signal of a preamp a certain way.

How so? Typically, that is...Anybody know?

[jdjustice]

Originally Posted by soupking

With API, Quad Eight, and other high gain preamps, it seems almost like a throw-in to have a pad for output.

I thought pads were used to bring the signal down, but as I've been reading, they seem to be an option to effect the signal of a preamp a certain way.

How so? Typically, that is...Anybody know?

i have wondered the same thing myself.....

[TRW]

A pad on the input before a microphone input transformer and gain stage is used to increase the headroom within the preamp...it will attenutate signal before the transformer (which will start to saturate at higher levels, each type is different). Transformers normally provide a little step up (free gain) and the amp does the rest. If you are clipping the preamp or the next device in the chain then an input pad is often employed.

However there are some thoughts that the resistive pad interferes with the mics inductive coupling to the input transformer and can change the sound.

Also for an effect, allowing the input transformer to saturate a little on loud sources by not using an input pad and running the amp wide open (where they may sound a little better - API etc) and then attenuating the output with another type of pad may provide more tonal options and mean you can run the pre hotter and not clip the next device in the chain - often a low headroom A/D converter in this day and age.

HTH
Tom

[soupking]

Oh cool, so it's a way of getting more headroom or meat out of a signal (depending on which end you put the pad) without running red in your gain staging?

That's sounds like something that would be employed very often when initially sculpting a guitar amp sound or something.

[TRW]

Exactly! Make mine a minestrone! thumbsup

-T

[soupking]

Who makes a decent pad? DW Fearn makes one, but they're a Line Input pad. That would make things difficult for putting it after the preamp since it's typically a Mic Output.

Am I Missing something? What's a good source?

[Daedalus77]

For API-style preamps, pick up an A-Designs ATTY (or two) or the more expensive rack-mount version.

These are pure, passive attenuators that will allow you to push the pres hard (into the red, if necessary), without engaging the input pad (which, to my ears, dulls the sound), but still trim the pre output so as not to clip your converters.

I have four APIs (well, two 512cs and two BAE 312s), and I always run them out through the ATTYs.

Hope this is helpful.

[soupking]

Very, thanks man!

[TRW]

Cheapest way is to build one in an XLR barrel...simple bit of soldering, a barrel and 3, 5 or 7(8) resistors depending upon which type of pad you use, balanced / unbalanced, simple voltage divider or H-pad...

I would recommend a 2k5 ohm bridged or unbridged H-pad for balanced or T-pad for unbalanced...

Get cocky and put it in a box with XLR in/out and use a 3 way 4 pole switch for various attenuation levels.

Still cheaper than an atty.

-Tom

[TRW]

Uneeda Audio - Build your own attenuator pads

[soupking]

Heh, not the way I solder. Thanks though TRW.

[Daedalus77]

With all due respect to TRW, the ATTY is $99.

An this is Gearslutz, after all.

We're not talking about an SSL Duality here.

Solder if you want, but I'd just grab a couple and call it a day.