Building Audiophile Sub with Peerless's XXLS 830845 - 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 9th May 2007, 03:34 AM   #11
Account disabled at member's request
 
MJL21193's Avatar
 
Join Date: Mar 2007
Quote:
Originally posted by Tiff_Needle
Hi there...

I would Like to know if anyone can help e with the LT circuit for this specific sub (Peerless 12" xxls - 830845) with th Ruthmik Audio A370 Plate amp?

I'm considering on purchasing rithmyk's plate amp and chaging it's RC values to achieve a better set for my sub.

I've made some plots and I've come up with a 110,6 L sealed box!

Is'nt it a box too big?

110 litres is too big if you are going to use a Linkwitz transform. That box size is good for this driver in a sealed box - will give the best response.
Strictly speaking, the driver is not the best choice for a LT, as the Fs is low. Part of the advantage of using an LT is to make the driver work below it's impedance peak. To make the impedance peak hapen at a higher frequency, you reduce the box size.
As far as the amp goes - it's ok, should give 300 watts at the~6 ohmsof this woofer. Depending on the amount of boost the LT provides, and the source material (music, HT) clipping shouldn't be a problem.
  Reply With Quote
Old 9th May 2007, 03:46 AM   #12
Account disabled at member's request
 
MJL21193's Avatar
 
Join Date: Mar 2007
For this driver, 50 litres would be a good size. Boost would be around 14dB, with a box Qtc of .85 and Fb of 44 Hz. This pushes your impedance peak up to 45 Hz. Not great, but about as good as this driver will get with a relatively low power amp and moderate boost.
  Reply With Quote
Old 9th May 2007, 05:51 AM   #13
diyAudio Member
 
RobWells's Avatar
 
Join Date: Aug 2002
Location: UK
If you're worried about excursion problems the last thing you want to do is LT the sub. Best bet is add a second driver.

Rob.
  Reply With Quote
Old 9th May 2007, 06:35 AM   #14
Calvin is offline Calvin  Germany
diyAudio Member
 
Calvin's Avatar
 
Join Date: Nov 2004
Location: close to Basel
Hi,

the dimensions are a result of the simulation I use. Since this is the same as used for a commercial product, please understand, that I don´t disclose the script. I could provide You with figures though. The experience gained over the years showed, that this script gives very precise and practical results, as long as the parameters of the driver are correct.
SL´s Site is a marvellously valuable piece of work and a must read for everyone interested in dipole technology.
Still though I prefer a similar but (always) smaller style of cabinet, that looks more pleasing to my eyes and that has distinct acoustical differences.
First it is a symmetrical cabinet, which Subs after SLs design are more than often not (if 2 or n*2 drivers are used) and second does it lower the Fs of the drivers condsiderably and raises Qt a bit. We´re talking of 5 to 10Hz reduction (sometimes more), depending on the driver and the cabinet´s size.
This has the advantage that You can use drivers with an slightly elevated Fs because of a stiffer suspension or/and lower diaphragm weight. This way You can use a lot of excellent PA-Drivers in the 15"-18"-class with remarkable results. They benefit from their good weight/force-relationship, their huge diaphragm size and their good highpower behaviour. What they usually lack (for homehifi) are a few Hz in Freq-response. But that is provided for by the very small cabinet (keep in mind that the shipping cartonage of the drivers is usually a bit larger than the actual cabinet size of this small dipole-type!! And the sim-figures I provided are for a pair of XXLS, hence ~24L for one XXLS vs. 50-110L in CB and still a lower Fs!).
The result can be an outstanding precise and deep bass with ´speed´ like no other. Sonically I´ve the impression of the combination of the goods of a Horn-bass with the ease and deep-going bass of an TL. There is of course a penalty to pay and that is a reduced efficiency and maximum SPL and a bit more of effort with the compartement building. But to me its worth trying ;-)
I find it much more comforting to have the driver do what it naturally wants to do, than to brute force him to an ´unnatural´ behaviour. While a L-transformed CB works fine on paper, in practise there will be audible sonic penalties, too much for my taste, but it might be ok for anybody else.

jauu
Calvin
  Reply With Quote
Old 9th May 2007, 07:51 PM   #15
Account disabled at member's request
 
MJL21193's Avatar
 
Join Date: Mar 2007
Quote:
Originally posted by RobWells
If you're worried about excursion problems the last thing you want to do is LT the sub. Best bet is add a second driver.

Rob.
Hi.
This driver in the configuration outlined in my previous post will not come near max excursion. Xmax for it is 13mm +/-, so about 1 inch in total. If anything, I'd reduce the box size even further, to drive up Fs, and increase LT boost and amp power. OR, skip LT altogether, and allign for a passive radiator in a small box.
As I've said before, this driver is not the ideal choice for an LT, better a higher efficiency, higher Fs pro type driver with a large Xmax.
  Reply With Quote
Old 9th May 2007, 08:38 PM   #16
diyAudio Member
 
RobWells's Avatar
 
Join Date: Aug 2002
Location: UK
Quote:
Originally posted by MJL21193


If anything, I'd reduce the box size even further, to drive up Fs, and increase LT boost and amp power.

I'm of the opposite opinion. I believe make the box as big as possible and use as little boost as possible. Gives you a bit more headroom before you run into power compression.

I believe the original post said the sub was to be used for 5.1 stuff too. For dvd material at reference a single 12 with 13mm xmax will struggle.

For example a 12" with 13mm xmax has a 1 way VD of approx 660cc's , which will do around 100dB at 20Hz. Dolby Digital needs around 115dB to do reference. That's without any bass redirection from the mains or surrounds. With all speakers set to small you'd need 121 / 122dB from the sub.

Cheers,

Rob.

Out of interest, what frequency did you have the 14dB boost at in your example above ?
  Reply With Quote
Old 9th May 2007, 11:33 PM   #17
Account disabled at member's request
 
MJL21193's Avatar
 
Join Date: Mar 2007
Quote:
Originally posted by RobWells



I'm of the opposite opinion. I believe make the box as big as possible and use as little boost as possible. Gives you a bit more headroom before you run into power compression.

Out of interest, what frequency did you have the 14dB boost at in your example above ?
Hi Rob,
When I said smaller box, it was strictly in reference to the Fs of the driver which is very low to begin with (22 Hz). The best advantage to LT is to make the driver work below Fs, thereby giving the amp a steady impedance to drive, rather than a large peak. A better driver for LT would be one with a higher Fs, such as 40 Hz, and of course, a bigger cone would also be good.

Like I mentioned before, this driver would work well in a small box with a passive radiator (or two), and with enough power should be able to hit ~ 120 dB at 20 Hz. This would probably be the best use for the driver IMO.
The frequency I used in the Linkwitz transform spreadsheet to calculate gain was 20Hz.
  Reply With Quote
Old 13th May 2007, 05:27 PM   #18
bjorno is offline bjorno  Sweden
diyAudio Member
 
Join Date: Mar 2005
Location: Jacobsmountain
Send a message via MSN to bjorno
Tiff Needle,

Quote:
Any suggestions?
Are you helped with these plots and calculations?

b

1(5)
Attached Images
File Type: gif peerless830845_lt-0.gif (36.5 KB, 959 views)
  Reply With Quote
Old 13th May 2007, 05:29 PM   #19
bjorno is offline bjorno  Sweden
diyAudio Member
 
Join Date: Mar 2005
Location: Jacobsmountain
Send a message via MSN to bjorno
2(5)
Attached Images
File Type: gif peerless830845_lt-1.gif (28.6 KB, 926 views)
  Reply With Quote
Old 13th May 2007, 05:30 PM   #20
bjorno is offline bjorno  Sweden
diyAudio Member
 
Join Date: Mar 2005
Location: Jacobsmountain
Send a message via MSN to bjorno
3(5)
Attached Images
File Type: gif peerless830845_lt-2.gif (26.3 KB, 914 views)
  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
peerless xxls sealed -vs- peerless xls with passive radiator Naudio Subwoofers 8 23rd March 2008 09:00 PM
Peerless 830845 Enclosure Drawings Needed lancer Subwoofers 3 5th May 2006 01:09 PM
Peerless XXLS 830845 suitability steve_mak Subwoofers 5 12th April 2006 04:13 AM
Plate Amp for XXLS 830845 ShockValue Subwoofers 2 24th October 2005 12:34 PM
FS: (2) Peerless 12" XXLS 830845 tf1216 Swap Meet 7 23rd October 2005 11:24 PM


New To Site? Need Help?

All times are GMT. The time now is 02:04 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