A Thread for those interested in PPSL enclosures - Page 2 - diyAudio
Go Back   Home > Forums > Loudspeakers > Subwoofers

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 4th May 2011, 12:50 PM   #11
hawkson is offline hawkson  United States
diyAudio Member
 
Join Date: Apr 2011
In case someone doesn't know what DJK is talking about(I didn't),
this explains the different types of subs
  Reply With Quote
Old 4th May 2011, 03:49 PM   #12
diyAudio Member
 
Join Date: Feb 2011
I'm going to Google 'PPSL djk' as suggested; I would like to experiment with a pair of B&C 21SW152. I'll model both sealed and vented implementations.

Larry
  Reply With Quote
Old 5th May 2011, 12:59 AM   #13
hawkson is offline hawkson  United States
diyAudio Member
 
Join Date: Apr 2011
Please update us on your models. i am interested in 18 inch drivers.
  Reply With Quote
Old 6th May 2011, 12:50 AM   #14
diyAudio Member
 
Join Date: Dec 2008
Quote:
Originally Posted by djk View Post
The basic idea behind PPSL is the plenum with the push-pull mounted drivers. The box could be sealed, vented, 6th order vented (most of my designs are 6th order vented), or even dipole (the Linkwitz sub).
So, to check my understanding, is there any difference between a sealed PPSL and a sealed isobaric? The principle seems the same. Has there been any comparison of the two?
  Reply With Quote
Old 6th May 2011, 01:09 AM   #15
djk is offline djk
diyAudio Member
 
djk's Avatar
 
Join Date: Feb 2001
Location: USA
The sealed PPSL is twice the size of the isobaric, and 3dB more efficient, with 6dB more maximum output.

"B&C 21SW152"

That looks like a nice driver, but it fits in a small box and the port required for the x-max the driver has may be a problem. Check the port size in your speaker program and see it you can make it work.

Most 18s don't look too bad, I have made a couple of different dual 18 PPSL for PA use.
__________________
Candidates for the Darwin Award should not read this author.
  Reply With Quote
Old 6th May 2011, 02:11 AM   #16
tb46 is offline tb46  United States
diyAudio Member
 
Join Date: Jan 2006
Location: Texas
Hi djk,

When I use the automatic alignment feature in Boxplot the isobarik configuration ends up 6dB down, and at 1/4 the volume.

Regards,
__________________
Oliver
  Reply With Quote
Old 6th May 2011, 02:16 AM   #17
hawkson is offline hawkson  United States
diyAudio Member
 
Join Date: Apr 2011
Quote:
Originally Posted by djk View Post
The sealed PPSL is twice the size of the isobaric, and 3dB more efficient, with 6dB more maximum output.

"B&C 21SW152"

That looks like a nice driver, but it fits in a small box and the port required for the x-max the driver has may be a problem. Check the port size in your speaker program and see it you can make it work.

Most 18s don't look too bad, I have made a couple of different dual 18 PPSL for PA use.

I am now deciding between a I) Dual Sealed Opposed build, II)multiple small sealed, and a III)PPSL Opposed Sealed. (Compound PPSL). DJK, most of the PPSL's you and Les online pictures of are Slot Loaded PPSL for PA. These seem harder to design and build than a PPSL Opposed Sealed design.

1. What is the advantage of having the plenum/slot loading manifold design in PPSL compared to a Dual Opposed PPSL.

2. Can you comment on the usage of PPSL for Home Theater? I've only seen you and Les building them for PA. Some users have commented that they won't work well down low??


Please correct me if I am wrong--
My current thoughts are to build a dual opposed PPSL. Why?
a) The design is easy, its like a Dual Opposed Sealed but with one driver and mount facing in.
b) In terms of modelling and building it, as long as I have enough internal space and amp power, what else should I worry about? Other designs have angles, horn length, port length etc. This design is a sealed box
c) This is better than 2 individual sealed 18's because of the ?even? harmonic cancellation. Right?


Thanks for the input, especially the parts in bold

Last edited by hawkson; 6th May 2011 at 02:19 AM.
  Reply With Quote
Old 6th May 2011, 11:47 AM   #18
bjorno is offline bjorno  Sweden
diyAudio Member
 
Join Date: Mar 2005
Location: Jacobsmountain
Send a message via MSN to bjorno
Quote:
..2. Can you comment on the usage of PPSL for Home Theater? I've only seen you and Les building them for PA. Some users have commented that they won't work well down low??
HI,My :

I would guess the PPSL shares similar SQ performance(= high) with a T-TQWT/T-TQWP if build sturdy, i.e. not letting any CSA:s larger than ~10x 10 to be un-braced.
The differences when placed in a room would be : The PPSL sums sound pressures in the far-field thus shows directionality but the T-TQWT/T-TQWP acts like an omni pressure point-source and is not sensitive if placed jammed very close to other in room objects. Its like comparing in room performance using a closed sub to a corresponding ported.


Quote:
..Please correct me if I am wrong--
My current thoughts are to build a dual opposed PPSL. Why?
a) The design is easy, its like a Dual Opposed Sealed but with one driver and mount facing in.
b) In terms of modelling and building it, as long as I have enough internal space and amp power, what else should I worry about? Other designs have angles, horn length, port length etc. This design is a sealed box ..
Comparing a closed PPSL would be like to compare with a closed T-QPPSL( easy to simulate in HR): Both offering very similar performance: Internally the the PPSL behaves like an ordinary closed box but the T-QPPSL like an closed TL,i.e. Lambda/2 behavior. See the picture:

b
Attached Images
File Type: gif T-TQWT-morphing-into-PPSL.GIF (77.2 KB, 2367 views)
  Reply With Quote
Old 6th May 2011, 01:20 PM   #19
tb46 is offline tb46  United States
diyAudio Member
 
Join Date: Jan 2006
Location: Texas
Hi hawkson,

Sorry, but I don't get what you mean with: "...a dual opposed PPSL... its like a Dual Opposed Sealed but with one driver and mount facing in..." Could you, please, provide a sketch of that arrangement?

As to the design of the enclosure, keep the driver plenum(s) as small as practical, and follow the same general rules you would use for a sealed box (or for a vented (bass reflex) if you decide to go that way). It may be interesting to design the box with ports you can stuff, or close.

Regards,
__________________
Oliver
  Reply With Quote
Old 6th May 2011, 03:51 PM   #20
Djim is offline Djim  Netherlands
diyAudio Member
 
Join Date: Dec 2009
Location: 'Ollanda
Quote:
Originally Posted by tb46 View Post
keep the driver plenum(s) as small as practical
Oliver, your statement suggests there is no relation between (minimum) opening size versus Response.
  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
PVC pipe enclosures with flat wood baffles - yet another dumb Spasticteapot thread. Spasticteapot Multi-Way 3 8th January 2007 05:35 AM
Might be interested in this distortion thread mashaffer Tubes / Valves 9 14th July 2004 01:08 PM
Interested ??? P901 Multi-Way 1 3rd December 2003 03:37 AM


New To Site? Need Help?

All times are GMT. The time now is 08:06 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