Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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 22nd July 2019, 05:30 AM   #11
jerryo is offline jerryo  Isle of Man
diyAudio Member
 
Join Date: Jun 2007
I have two pairs of these drivers in storage and have considered a clamshell isobaric build but I know that the t/s parameters vary quite a bit from the original values through storage.
These drivers offer the possibility of bonding the two driver faces together giving zero volume between them which is perfect for isobaric. How would you treat the t/s parameters though for vas and box volume calculation. Take the actual driver measurements and run those through an isobaric setting on say winisd Or measure the two bonded drivers t/s parameters considering them as one driver? Difficult to do added mass method for vas
As it is winisd has given me a nice flat, low response in a 43 litre box to a -3db of sun 30hz as a clamshell isobaric. (No extra internal volume for second driver)
If two of these drivers having differing t/s parameters are bonded together face to face their individual parameters will be averaged between them, no/yes?
  Reply With Quote
Old 25th July 2019, 06:49 PM   #12
badman is offline badman  United States
diyAudio Member
 
badman's Avatar
 
Join Date: Sep 2003
Location: Ashland, MA
The best choice is to use a push-pull manifold, with the drivers spaced as closely as you can (while respecting that they need at least 2cm of clearance between cone/magnet for safety). From there, you can take the driver specs and plug them into a box designer with 2 drivers. Fc and will likely be a touch lower due to the airload, but it may not be measurable in impact (on a downfiring manifold, you get effectively a much more bandpass-like behavior, beneficial for a sub).

But in any case, push-pull is like a better isobaric for distortion and output reasons (but with 2x the box size).
__________________
"The dawn of Bose created the "Man Cave" and reduced testoterone levels worldwide by 18.5 per cent" Peteleoni
  Reply With Quote
Old 25th July 2019, 07:11 PM   #13
jerryo is offline jerryo  Isle of Man
diyAudio Member
 
Join Date: Jun 2007
I was under the impression that a clamshell isobaric set up was probably best. The B139 drivers are perfect for this because of their flat faced cones allowing, as mentioned, the possibility of bonding the two cone faces together therefore giving zero enclosed air mass, which also helps with overall box size. I’ll probably give it a go and then measure the resultant combined double driver and see what the t/s specs turn out to be.
  Reply With Quote
Old 25th July 2019, 08:22 PM   #14
tsmith1315 is offline tsmith1315  United States
diyAudio Member
 
tsmith1315's Avatar
 
Join Date: Jul 2003
Location: Doerun, GA
jerryo, read again and you'll see that badman is not suggesting an isobarik system, but a manifold.

It's two drivers loaded into a slot with an open end, with one driver mounted backwards, thus wired out of phase. "Push-pull" is relative to the baskets, not relative to the manifold/listener. The output of both cones radiates through the slot. Isobarik pairs only have one radiating surface.

Clamshell mounting gives the same, if not better, properties of cancelling basket resonance/distortion because the baskets are usually mounted on opposite sides of the same baffle, thus more closely coupled. Sensitivity is 6dB better in the manifold, at a cost of 4x the required internal box volume.
__________________
Tim
  Reply With Quote
Old 26th July 2019, 04:58 AM   #15
jerryo is offline jerryo  Isle of Man
diyAudio Member
 
Join Date: Jun 2007
I realise that, but as you point out there is a considerable increase in box size. I don’t need high spl’s but rather a compact box volume and depth of bass.
  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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Simulating different woofers sharing the same chamber andreaemme Multi-Way 17 1st March 2019 02:01 PM
Tips on making cables Peter Pan Construction Tips 6 31st January 2015 05:01 PM
Linn Isobarik PSM midrange and Bass units 2SA991 Swap Meet 0 22nd September 2014 05:18 PM
Double Chamber Reflex - tips? gafhenderson Full Range 14 14th August 2013 06:55 PM
Linn majik isobarik active bass xover audiobomber Multi-Way 2 26th November 2012 06:42 PM


New To Site? Need Help?

All times are GMT. The time now is 12:55 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki