Geddes on Acoustic Lever - Page 3 - 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 2nd December 2009, 09:41 PM   #21
diyAudio Member
 
Join Date: May 2009
Location: Wellington
Inasmuch as it is an integral part of Earl's design, whereas Altec attempted to eliminate it, yes I'm sure.
  Reply With Quote
Old 2nd December 2009, 10:54 PM   #22
diyAudio Member
 
john k...'s Avatar
 
Join Date: Aug 2004
Location: US
Earl, I won't argue that the differences between conventional PR and your AL. Yes, they are there, but mechanically it is still an mass/spring resonator coupled to the driver by a spring. At low frequency it will follow the driver, at resonace it will peak and at high freuqency the response will fall off.

If you draw the mechanical mobility schematic for a BP PR and a BP AL aren't they are identical except for the additon of a compliance element between the moving mass element (the PR or double disk) and ground in the case of the AL? I think so. Differences come in the values of the parameters. It is precisely the difference in area of the disks which leads to different volume velocities which creates the additional compliance element as it leads to compression/expamsion of the air in the common chamber. Make the disks equal in area and this compliance element goes away.
__________________
John k.... Music and Design NaO Dipole Loudspeakers.
  Reply With Quote
Old 2nd December 2009, 11:37 PM   #23
dlr is offline dlr  United States
diyAudio Member
 
Join Date: Mar 2005
Location: Canton, MA
Quote:
Originally Posted by gedlee View Post
Of course, but that's all been done. It's been studied and quantified completely. There is nothing left but making them. I would gladly design a lever system if someone would fabricate the lever component itself and agree to sell it at a fair price (TBD). But with tooling etc. that's a big load to carry for a risky business.
Am I missing something or is the lever component simply a solid rod connection between the PRs? If so, many of today's PRs have a rigid coupling on the back for adding weight that is usually a metric thread into a solid disc. All one need do is mount them back-to-back with the correct length threaded rod. Those made by Peerless or Seas are pretty solid units. The area ratios are limited, but what's available off-the-shelf may still be sufficient.

Dave
  Reply With Quote
Old 2nd December 2009, 11:54 PM   #24
diyAudio Member
 
john k...'s Avatar
 
Join Date: Aug 2004
Location: US
Quote:
Originally Posted by dlr View Post
Am I missing something or is the lever component simply a solid rod connection between the PRs? If so, many of today's PRs have a rigid coupling on the back for adding weight that is usually a metric thread into a solid disc. All one need do is mount them back-to-back with the correct length threaded rod. Those made by Peerless or Seas are pretty solid units. The area ratios are limited, but what's available off-the-shelf may still be sufficient.

Dave

That's about it Dave.
__________________
John k.... Music and Design NaO Dipole Loudspeakers.
  Reply With Quote
Old 3rd December 2009, 12:28 AM   #25
Account disabled at member's request
 
MJL21193's Avatar
 
Join Date: Mar 2007
I doubt the gain realized is worth the extra complexity. Much better / easier / cheaper to use a driver of the same size as the outer piston.
  Reply With Quote
Old 3rd December 2009, 02:23 AM   #26
gedlee is offline gedlee  United States
diyAudio Member
 
Join Date: Dec 2004
Location: Novi, Michigan
Quote:
Originally Posted by john k... View Post
Yes, they are there, but mechanically it is still an mass/spring resonator coupled ... .
Hi John

Yes, its a bandpass system, nothing new there, and yes if you make the two pistons the same size then its just a bandpass system with a PR. But the two disks AREN'T the same size, thats the point. Up to 6 dB more efficiency is nothing to scoff at. Try to double efficiency any other way.
  Reply With Quote
Old 3rd December 2009, 02:28 AM   #27
gedlee is offline gedlee  United States
diyAudio Member
 
Join Date: Dec 2004
Location: Novi, Michigan
Quote:
Originally Posted by MJL21193 View Post
I doubt the gain realized is worth the extra complexity. Much better / easier / cheaper to use a driver of the same size as the outer piston.
It doesn't double the efficiency, maybe 2-3 dB tops. And the driver then costs more. For the cost of a simple modfied PR you get the same out as if you had TWO drivers. This was the test that we did and showed that it does work. One driver and a lever had precisely the same output as two drivers - and the same cone excursion, BUT 1/2 THE POWER WAS REQUIRED.

One driver and a PR is a LOT cheaper than two drivers and twice the amp power.
  Reply With Quote
Old 3rd December 2009, 02:36 AM   #28
Account disabled at member's request
 
MJL21193's Avatar
 
Join Date: Mar 2007
I can fully appreciate how it works and don't dispute there would be a gain in efficiency but at the cost of bandwidth (like you've said) - low frequency cut off is the big one. We could live (actually welcome) the high frequency limit in a sub but the result looks like a one note wonder.
I think I'd gladly trade higher power / price for lower extension.
Interesting idea though.
  Reply With Quote
Old 3rd December 2009, 02:43 AM   #29
tinitus is offline tinitus  Europe
diyAudio Moderator R.I.P.
 
Join Date: Nov 2005
What if you reverse it in a 6.order BP
The low port replaced by the PR design
  Reply With Quote
Old 3rd December 2009, 02:53 AM   #30
dlr is offline dlr  United States
diyAudio Member
 
Join Date: Mar 2005
Location: Canton, MA
Quote:
Originally Posted by gedlee View Post
It doesn't double the efficiency, maybe 2-3 dB tops. And the driver then costs more. For the cost of a simple modfied PR you get the same out as if you had TWO drivers. This was the test that we did and showed that it does work. One driver and a lever had precisely the same output as two drivers - and the same cone excursion, BUT 1/2 THE POWER WAS REQUIRED.

One driver and a PR is a LOT cheaper than two drivers and twice the amp power.
What tunings are reasonable? That is, the latest PRs tend to be tuned very, very low to give extra extension with targeted woofers and are frequently tuned below the lowest musical notes, so the highpass system F3 is usably low, especially for music only. Would the gain allow for more output at lower tunings or is it not suitable for very low tunings? Considering that two PRs are required, it does seem that the requirements for each one may limit the options.

Dave
  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
Geddes on Waveguides Variac Multi-Way 7007 16th August 2014 05:19 PM
Attn. Dr. Geddes: What about acoustic lenses? NV&H Multi-Way 7 9th June 2014 10:23 AM
Dual CS 5000 Cueing Lever Question seinfeld Analogue Source 10 7th July 2012 11:41 AM
slaps = acoustic lever? jbell Subwoofers 3 18th February 2009 10:17 PM
Leader LMV-1815 2 Ch Auto dB Lever Meter Mikewong Analogue Source 0 19th July 2007 06:27 AM


New To Site? Need Help?

All times are GMT. The time now is 04:23 PM.


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