L-pads????? - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way

Multi-Way Conventional loudspeakers with crossovers

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 26th November 2002, 11:35 AM   #1
diyAudio Member
 
Join Date: Nov 2002
Location: brisbane
Question L-pads?????

I like the idea of being able to adjust the level of the tweeter.... a book I am reading suggests using an L-pad to supply an adjustable resistance across and in series with a driver, calls it an L-pad - I am thinking it is similar to a potentiometer, but have never seen one...

does anyone know where to source them from in Australia???
  Reply With Quote
Old 26th November 2002, 12:22 PM   #2
Account Disabled
 
Join Date: Oct 2002
You should read my thread, its very similar to your question. Yes an L-pad is just a big pot, but you may have to wire it differently that just in series to avoid any problems.

Inline resistor raise speaker impedence?
  Reply With Quote
Old 26th November 2002, 12:48 PM   #3
diyAudio Member
 
mrfeedback's Avatar
 
Join Date: Feb 2002
Location: Perth, Australia.
Default Sign off With A Real Name Ok.....DIYetiquette

You can phone Wes Components - Ph: 02-9797-9866
or phone me (08-9405-9779) - I have the full print copy of the catalogue.
Many older speakers used them.
General regard is that they are not for audiophile usage, but can be useful temporaryily for determination of appropriate level, and then replaced with fixed resistors, or a rotary switch with a set of attenuation values.
Experience dictates that the resistive (nichrome ?) wire that they are made from forms a hard oxide film that causes dynamic contact resistance and thereby roots the sound.
Treatment with something like Caig Deoxit helps very much (even brand new ones), and helps long term ensurability.
Other contact treatments can bugger it up.

Eric.
  Reply With Quote
Old 26th November 2002, 04:11 PM   #4
diyAudio Member
 
FrankDIY's Avatar
 
Join Date: Mar 2001
Location: Quebec City
This is exactly what I am doing, I tweak with L-Pad and use fixed resistor for the final version of the board.
__________________
Imagination is more important than knowledge. knowledge is limited, imagination encircles the world. Albert Einstein
FrankDIY's Audio Corner
  Reply With Quote
Old 26th November 2002, 11:53 PM   #5
diyAudio Member
 
mrfeedback's Avatar
 
Join Date: Feb 2002
Location: Perth, Australia.
Quote:
Originally posted by Westrock2000
You should read my thread, its very similar to your question. Yes an L-pad is just a big pot, but you may have to wire it differently that just in series to avoid any problems.

Inline resistor raise speaker impedence?
An L-Pad is not a pot - it is 2 variable resistors - one in series, and one in shunt.
The values are configured such that a reasonably constant load is presented to the amplifier, and variable level fed to the load driver.

Eric.
  Reply With Quote
Old 12th May 2004, 03:41 PM   #6
paulj is offline paulj  Australia
diyAudio Member
 
Join Date: Jan 2004
Location: Warrandyte - outer "bush" suburb on the Yarra River, outside Melbourne Australia
Default Looking for L-pads in Australia

I've come across this old thread - I'm looking for L-pads here in Australia. 100 watt, 8 ohm. Can anyone help?

Cheers, Paul
  Reply With Quote
Old 13th May 2004, 06:31 AM   #7
lucpes is offline lucpes  Europe
diyAudio Member
 
Join Date: Dec 2003
Location: Iasi
Send a message via Yahoo to lucpes
L-pad is formed out of two resistors, you don't need 100W ratings, 5W or 10W would be more than enough (for the tweeter). Google a 'L-pad calculator' and buy the two resistors
  Reply With Quote
Old 13th May 2004, 08:15 AM   #8
paulj is offline paulj  Australia
diyAudio Member
 
Join Date: Jan 2004
Location: Warrandyte - outer "bush" suburb on the Yarra River, outside Melbourne Australia
Thanks for your advice lucpes. I'll go out and buy the resistors and try some different amounts of attenuation.

A question for you - (excuse my ignorance with circuit diagrams): am I right in assuming the two resistors R1 and R2 are inserted on the "tweeter side" of the crossover capacitor?

Regarding the power handling of the resistors, the tweeters are bi-wired and bi-amped with an amplifier that is 65 w RMS/8ohms per channel. Would you still be happy with 5 or 10watts per resistor?

Many thanks, paul
  Reply With Quote
Old 13th May 2004, 08:27 AM   #9
Andy G is offline Andy G  Australia
diyAudio Member
 
Andy G's Avatar
 
Join Date: Apr 2002
Location: Newcastle, Australia
http://www1.jaycar.com.au/productVie...Max=&SUBCATID=


This is the fella you want.. and a heap of 5w or 10w resistors

and with a bit of thinking, you can get up to 6 positions with a solid switch between each position......not a variable slide contact !!!

Have fun figuring it out !!!

here's an L-pad calc

http://www.mhsoft.nl/spk_calc.asp#att
  Reply With Quote
Old 13th May 2004, 09:02 AM   #10
paulj is offline paulj  Australia
diyAudio Member
 
Join Date: Jan 2004
Location: Warrandyte - outer "bush" suburb on the Yarra River, outside Melbourne Australia
Thanks Andy! Can you tell me where I put the R1 and R2 [ between the crossover capacitor and the tweeter or on the amplifier side of the capacitor? (All the diagrams I've seen only show the R1 and R2, not the cap, and I'm a beginner!)

Also, will the 10 watt resistors stand up to the power of my amp? There don't seem to be any resistors rated at more than 10 watts on the Jaycar site. Is there any point in "ganging them up" for extra power handling or does this screw up the impedances?

Thanks, Paul
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
sound pads 8cube Planars & Exotics 1 13th January 2009 01:45 AM
sound pads ibanezeros Planars & Exotics 4 16th January 2006 06:40 PM
Insulating Pads. castlesteve Chip Amps 28 29th October 2004 02:35 AM
pads rulezzz Chip Amps 1 11th January 2004 02:35 PM
Isolation pads Devil_H@ck Parts 9 7th January 2004 05:25 PM


New To Site? Need Help?

All times are GMT. The time now is 09:05 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2