Difference between revisions of "Pad"

From Bose Portable PA Encyclopedia
Jump to: navigation, search
m (added some 'why' info, per ST's request)
m (Model II Power Stand to A1)
 
(24 intermediate revisions by 4 users not shown)
Line 1: Line 1:
Q: What is a Pad?
+
<table cellpadding="10"><tr>
 +
<td valign="top" width="250" >__TOC__</td>
 +
<td valign="top">
 +
 +
Q: What is a Pad?  
  
A "pad" is short for an "Attenuation Pad".
+
A: "pad" is short for an "Attenuation Pad".  
  
This is a device used to lower the signal level between two other devices.
+
This is a device used to lower the signal level between two other devices.  
  
"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."
+
With the L1® family of products, the most likely place you will use this is in front of a [[Model I]] (or [[Classic]]) Power Stand Channel 1 or Channel 2.
  
We use them with our Bose Systems when running a pro level +4 dBu signal (e.g. output from a mixer) to the XLR inputs on Channels 1 or 2 on the PS1 Powerstand. 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.
+
[[File:Pad.jpg|link=http://www.bing.com/search?q=whirlwind+IMPAD20|200px|Find them on the web]]
 +
* Cost: $20-30 on the web
  
Values of attenuation are expressed in decibels, dB. dBu/dBV/dBm are ratios/references. (dBm is a ratio of power, relative to 1mW. dBu and dBV are ratios of voltage, relative to 0.775V and 1V, respectively.) When determining how much of a pad is needed, we want to compare apples-to-apples by converting specs (e.g. http://www.sengpielaudio.com/calculator-db-volt.htm) to a common reference. For the 'mixer line-output to PS1 mic-input' scenario, -20 dB is a good choice because it brings the hot, line-level signal down to a lower voltage range that a mic pre can easily handle.
+
Sources:
 +
* [http://www.bing.com/search?q=whirlwind+IMPAD20 Search results on the web]
 +
*You might find something like this in a local music store if they have a Pro Audio department.
 +
</td>
 +
</tr></table>
  
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.
+
=== Pad between {{Model II}} and {{A1}} ===
 +
If you are using a {{Model II}} with a {{B2}} and an {{A1}}, you may find that the Red LED on the {{A1}} lights up earlier than expected. You can put a 10 dB Pad between the Model II Power Stand Bass Line Out and the {{A1}} input.  
  
Another application (although relatively rare) is if you want to daisy-chain the Line-Out of one PS1 Powerstand 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.
+
Unfortunately most Pads have XLR connectors, so you may need to get some Tip-Ring-Sleeve to XLR adapters to make all the connections.
  
You can find separate attenuation pads like this:
 
  
[[Image:Pad.jpg]]
 
  
Example [http://www.proaudiosolutions.com/prod.itml/icOid/9512 IPAD20]
 
  
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.
+
=== Pads for {{PS1}} Inputs  ===
 +
{{Model I icon}} {{Classic icon}}
 +
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.  
  
References:
+
Pads can also help when connecting the Power Stand Line Outs to semi-pro or consumer recording devices. If the Power Stand Line Outs are too high for the recorder's inputs, a pad can be used to prevent overdriving those inputs into clipping distortion.  
* [http://www.rane.com/par-a.html Rand Professional Audio Reference]
 
* [http://www.uneeda-audio.com/pads/ All About Pads]
 
  
 +
==== Signal Source that has a Pad ====
 +
Check your source device (mixer or DJ mixer) to see if there is an attenuation switch. This may be marked Line/Mic or show -10dB or similar markings. If you have a switch like this, try it. It may give you the same benefits of using a pad.
  
[[category:Gear]]
+
=== Pad with {{PS1}} Line Outs ===
[[category:Mixer]]
+
A -20dB pad is also a good choice when connecting the Power Stand 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.)
[[category:Terminology]]
+
 
 +
=== {{T1}} No Pads Required  ===
 +
{{T1 icon}}
 +
{{: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. {{Why Use a -20 dB Pad}}
 +
 
 +
See [[PS1 Powerstand / Daisy Chain]] for more information.
 +
 
 +
You can find separate attenuation pads like this:
 +
 
 +
[[File:Pad.jpg|link=http://www.bing.com/search?q=whirlwind+IMPAD20|200px|Find them on the web]]
 +
 
 +
Cost: $20-30 on the web
 +
 
 +
Sources:
 +
* [http://www.bing.com/search?q=whirlwind+IMPAD20 Search results on the web]
 +
*You might find something like this in a local music store if they have a Pro Audio department.
 +
 
 +
This is 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]]
 +
[[Category:Daisy Chain]]

Latest revision as of 17:26, 14 May 2017

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.

With the L1® family of products, the most likely place you will use this is in front of a Model I (or Classic) Power Stand Channel 1 or Channel 2.

Find them on the web

  • Cost: $20-30 on the web

Sources:

Pad between L1 Model II and PackLite® power amplifier model A1

If you are using a L1 Model II with a B2 Bass Module and an PackLite® power amplifier model A1, you may find that the Red LED on the PackLite® power amplifier model A1 lights up earlier than expected. You can put a 10 dB Pad between the Model II Power Stand Bass Line Out and the PackLite® power amplifier model A1 input.

Unfortunately most Pads have XLR connectors, so you may need to get some Tip-Ring-Sleeve to XLR adapters to make all the connections.



Pads for PS1 Power Stand (Classic) / Model I Inputs

L1 Model I This information is applicable to the L1 Model I
Classic This information is applicable to the L1® Classic

We use pads with our PS1 Power Stand (Classic) / Model I'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 Power Stand Line Outs to semi-pro or consumer recording devices. If the Power Stand Line Outs are too high for the recorder's inputs, a pad can be used to prevent overdriving those inputs into clipping distortion.

Signal Source that has a Pad

Check your source device (mixer or DJ mixer) to see if there is an attenuation switch. This may be marked Line/Mic or show -10dB or similar markings. If you have a switch like this, try it. It may give you the same benefits of using a pad.

Pad with PS1 Power Stand (Classic) / Model I Line Outs

A -20dB pad is also a good choice when connecting the Power Stand 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 ToneMatch Audio Engine No Pads Required

T1 This information is applicable to the T1 ToneMatch® audio engine


The T1® XLR inputs on channels 1-3 were designed to accept inputs from microphones up to normal line-level inputs without needing a switch or a pad. This is in unlike the L1 Model I or L1 Classic) Power Stand where a pad is recommended for line-level inputs.

The T1 ToneMatch® Audio Engine Channels 1, 2, 3 inputs will accept a wide range of signals. We have not encountered a normal use where someone needed a pad - even using +4dbU console outputs, which is as high as it gets.
— MikeZ-at-Bose[1]

  1. MikeZ-at-Bose talks about T1® XLR inputs

Daisy Chaining PS1 Power Stand (Classic) / Model Is

Another application (although relatively rare) is if you want to connect the output of one PS1 Power Stand (Classic) / Model I to input of another. Sometimes called daisy chaining, you can connect the Line-Out of one PS1 Power Stand (Classic) / Model I 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. Why use a -20 dBu Pad?

The XLR connects to a balanced low impedance input stage with a lot of gain. The 1/4" input is unbalanced, has about 20 dB less overall gain but a very high input impedance. [1]

See PS1 Powerstand / Daisy Chain for more information.

You can find separate attenuation pads like this:

Find them on the web

Cost: $20-30 on the web

Sources:

This is 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.

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.

Source: Rick Chinn / Uneeda Audio


References:

  • Hilmar-at-Bose talks about Channels 1 and 2