Pad

2009-05-25T16:40:09Z

Dr.Rhythm: /* Do It Yourself */

Q: What is a Pad?

A "pad" is short for an "Attenuation Pad".

This is a device used to lower the signal level between two other devices.

=== Padding {{PS1}} Inputs ===

We use pads with our {{PS1}}s when running a pro level +4 dBu signal (e.g. output from a mixer) to the XLR inputs on Channels 1 or 2. We want to do this because the input sensitivity for these inputs is set for microphones. To get a better match for levels between the source and our inputs, we can use a pad.

Pads can also help when connecting the PS1 Line Outs to ''semi-pro'' or ''consumer'' recording devices. If the PS1 Line Outs are too ''hot'' for the recorder's inputs, a pad can be used to prevent overdriving those inputs into (clipping) distortion.

A -20dB pad is also a good choice when connecting the PS1 Line Outs to a house PA, or other off-stage system. This would ensure that the house mixing console's inputs can handle the signal level without being overdriven into distortion, especially if the house console has insufficient built-in pads, or none at all. (Beware of the potential for Ground Loops here.)

=== {{T1}} No Pads Required ===

{{:T1 ToneMatch® Audio Engine / XLR Inputs Sensitivity}}

=== Daisy Chaining {{PS1}}s ===

Another application (although relatively rare) is if you want to connect the output of one {{PS1}} to input of another. Sometimes called ''daisy chain''ing, you can connect the Line-Out of one {{PS1}} to Channel 1 or 2 of another. In that case you probably want to have a -20 dB pad inline, between the Line-Out of the first System and the Channel 1 or 2 XLR input of the second. See [[PS1 Powerstand / Daisy Chain]] for more information.

You can find separate attenuation pads like this:

[[Image:Pad.jpg]]

Cost: $20-30 on the web

Sources:

*http://www.proaudiosolutions.com/product_p/impad20.htm
*http://www.musiciansbuy.com/WHIRLWIND_IMPAD20_IMPEDANCE_CONVERTERIMPAD20.html
*You might find something like this in a local music store if they have a Pro Audio department.

This an example, and you will want to look into the details to determine if you need a pad, and the kinds of connections that are appropriate for your input device.

== More Formal Definitions ==

"attenuator or attenuator pad Electronics. A passive network that reduces the voltage (or power; see usage note under gain) level of a signal with negligible distortion, but with insertion loss. Often a purely resistive network, although any combination of inductors, resistors and capacitors are possible, a pad may also provide impedance matching."

== Do It Yourself ==
An inline pad can be easily soldered, you'll need to insert 3 resistors into your mic cable. The values of these three resistors are determined by the amount of attenuation you wish to achieve. Bose recommends -20dB of attenuation to bring a hot +4dBu balanced line level signal down to a voltage that the Bose PS1 (Classic) Mic inputs can handle.
<blockquote>
To build a -20dB attenuation pad insert the following three resistors into your XLR cable path.

*Two 680 ohm resistors inserted into lines (pins) 2 and 3
*One 150 ohm resistor inserted across pins 2 and 3

To minimize the effect on common mode rejection, you should use 1% resistors, but common-ordinary 5% carbon film resistors will work. For microphone pad applications, 1/4 watt or less is fine.
</blockquote>

Source: [http://www.uneeda-audio.com/pads/ Rick Chinn / Uneeda Audio]

<br> References:

*[http://www.rane.com/par-a.html Rane Professional Audio Reference]
*[http://www.uneeda-audio.com/pads/ All About Pads]

[[Category:Gear]]
[[Category:Mixer]]
[[Category:Terminology]]
[[Category:Pad]]
[[Category:XLR]]

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Pad