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

Drivers /  parameters for ripole subs
Drivers /  parameters for ripole subs
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
Thread Tools Search this Thread
Old 19th September 2006, 08:46 PM   #21
Rudolf is offline Rudolf  Germany
diyAudio Member
Rudolf's Avatar
Join Date: Mar 2003
Location: Germany
Default About ripole dimensions (continued)

Well, I am not shure I should follow Paul´s nomenclature from the post above. I would still prefer to call the horizontal dimension of the ripole pipe opening it´s width. Otherwise he is mostly on topic. But maybe I can tell it even more precisely.

When we look at the most prominent difference between a common Linkwitz style W frame and a ripole it optically boils down to less width. But that´s not for style, but with reason. One design target for the ripole was to achieve an almost flat frequency response with only marginal electronic bass EQ. This was done by kind of mass loading the driver and raising the system Q that way. In a wide pipe the air volume would move freely and SPL would drop early. In a narrow pipe the air is more resistive against cone movement. Thus the cone can couple its energy more efficiently to the air mass. Narrowing the pipe has it´s limit when efficiency drops radically and the moving air becomes noisy. Comparable to a BR tube becoming too small.

The rule of thumb here is: If the drivers Xmax (peak-to-peak) is >10 mm, the opening area of the pipe should be not less than 1/3 Sd. If Xmax is less, the area might be reduced down to 1/4 Sd.

The pipe opening at the rear of the driver should be between 1/2 Sd and 1 Sd. The performance of the ripole is predominantly determined by the front pipe. There is no real need to get both volumes equal. But if you add the cone volume to the front pipe volume and subtract the same cone volume from the rear pipe volume you will get comparable volumes in many cases anyway.

A second design target for the ripole was the lowering of Fs. This can easily amount to 10 Hz reduction. A bigger VAS will result in a bigger reduction of Fs. So it is no use to look for rock bottom Fs under ~25 Hz in a driver.

This is definitely everything I can tell you about the ripole dimensions. Tomorrow I will try to add some comments regarding driver parameters and the – too much neglected – passive equalising cum notch filter.

  Reply With Quote
Old 19th September 2006, 09:35 PM   #22
Nuuk is offline Nuuk  United Kingdom
diyAudio Member
Nuuk's Avatar
Join Date: Feb 2003
Location: Somerset, SW England
Moray asked me to mention a couple of drivers in connection with this subject of this thread.

The Max Pentivents are very well made, have a vented pole piece and from what I have heard testing a couple of 12 inchers in a W baffle, they work well for dipole bass.

Here are some specs.

An externally hosted image should be here but it no longer works. Please upload images instead of linking to them to prevent this.

I know of one member here who uses the PV1550!

I believe that the Pentivents are available on both sides of the Atlantic.

And Hemp acoustics are working on a 15 inch dipole woofer that will have an Xmax of 14 mm.
The truth need not be veiled, for it veils itself from the eyes of the ignorant.
  Reply With Quote
Old 19th September 2006, 09:45 PM   #23
bibster is offline bibster  France
diyAudio Member
bibster's Avatar
Join Date: Aug 2004
Location: Lasbordes, 11400

You seem, no, you ARE absolute way more informed/experienced on the subject, so I'll follow your nomenclature
(I called it HEIGHT becouse in many of the pictures I've seen the cabinets seem to be 'laying down', the driver's horizontal, get it?)

I didn't know the Sd/front-mouth relationship was related to the Xmax, nor the Sd/rear-mouth width relationship, thanks!

I'll try to make some spreadsheet tomorrow to figure some values based on our common knowledge. As a matter of fact I've allready made one, just to calculate the wood dimensions (Bored at 'work' you see... )
So, for this S-sheet's enhaced version we need: Sd, driver's outside diameter, driver's height (To get rid of the hole in the back, if possible. That's a pita to achive...), Xmax, wood thickness, right?

Is there, or rather, do we yet know how to predict the Fs lowering, based on Vas, chamber size and some other parameters?

Regards, Tschüß, doeg, a+, Paul
Demagogue: One who preaches a doctrine he knows to be untrue to men he knows to be idiots.
H.L. Mencken
  Reply With Quote
Old 20th September 2006, 04:38 AM   #24
v-bro is offline v-bro  Netherlands
diyAudio Member
v-bro's Avatar
Join Date: May 2006
I sometimes pity the fact that manufacturers are not at all clear on mechanical capabilities of their speakers, let alone noises produced by air displacement or cone breakup(flapping?wow, seems bad to me!).

Information on this shouldn't be limited to experience or guessing(knowing the materials and build).

Isn't there a way to produce free air specs based on showing all behavior other than desired?

Or don't they try becouse they're afraid of the results?

Or is it impossible to distinguish them that way becouse some flapping speaker can behave exellent in some enclosure design?

For a ripole I think a free air mechanical power capability graph(frequency related to max. electrical power connected in a sine-wave pattern keeping all within reasonable margins of distortion for example) might be helpfull.
Max. cone displacement can be several foot on any speaker!Too bad it can be done only once......
  Reply With Quote
Old 20th September 2006, 10:22 AM   #25
bibster is offline bibster  France
diyAudio Member
bibster's Avatar
Join Date: Aug 2004
Location: Lasbordes, 11400

Here's my Q'n'D ripole calc sheet, mainly for cabinet construction though...
It's a preliminary V0.0001 alpha release
Send comments/improvements etc. to my email rather than here, I don't want to mess up this usefull thread!

regards, (Ri)Paul
Attached Files
File Type: zip ripole.zip (7.6 KB, 666 views)
Demagogue: One who preaches a doctrine he knows to be untrue to men he knows to be idiots.
H.L. Mencken
  Reply With Quote
Old 20th September 2006, 03:04 PM   #26
Rudolf is offline Rudolf  Germany
diyAudio Member
Rudolf's Avatar
Join Date: Mar 2003
Location: Germany
Since this thread is about drivers and parameters, I should contribute some too.

In general Axel Ridtahler and some other competent ripole guys recommend a target system Q of ~0.7 to 0.9. This will be best achieved with driver Qts 0.5-0.7. But any Qts from 0.35 to 1 may be taken into consideration too.

Fs should be between 25 and 45 Hz. Remember that Fs reductions of 10-15 Hz for the ripole system are quite common!
VAS is indicative for the stiffness of the suspension. A PA driver with stiff accordion surround and resulting lower VAS would get less Fs reduction than a driver with a “loose” rubber surround.

Mms should be within reason. So better no 10 inch driver with a 120 g cone! Even 12 inch drivers should need no more mms than 80-120 g to give good results. 15 inch drivers should be content with mms < 160 gr.
So for instance mms-wise the Peerless SLS series would be suited much better than the XLS drivers.

Drivers that have been explicitly “approved” by those ripole guys or have been applied with good results are:
  • Peerless SLS series
  • Vifa 30 WN 380 RL/8 Fs=21 Hz, Qts=0.21, Mms=61 g, VAS=328 l, Sd=507 cm²
    (This driver reportedly had been produced to Ridtahler´s specifications and doesn´t really comply with the “rules” above. So you don´t have to stick to those rules too much too)
  • GBS 515 Fs=24 Hz, Qts=0.47, Mms=160 g, VAS=257 l, Sd=835 cm²
    (This discontinued driver was offered at the German ebay and is clearly the bigger brother of the RBS 512. Don´t confuse it with the new GBS 515 or GBS 5115, which are offered by the same vendor). TSPs are taken from an independent source: http://www.hifi-selbstbau.de/text.php?id=119&s=read
  • RBS 512 Fs=29 Hz, Qts=0.42, Mms=196 g, VAS=61 l, Sd=531 cm²
    (This driver has been approved by Ridtahler himself - notwithstanding the high mms)
  • A&D 1530 Fs=46 Hz, Qts=0.48, Mms=xx, VAS=142 l, Sd= ~900 cm²
  • A&D 1830 Fs=34 Hz, Qts=0.64, Mms=xx, VAS=265 l, Sd=~1400 cm²
  • Visaton W 300 Fs=32 Hz, Qts=0.55, Mms=43 g, VAS=190 l, Sd=490 cm²
I know most of these drivers are only sold in Europe, but they should just show what to look for.

  Reply With Quote
Old 20th September 2006, 03:58 PM   #27
nilsomat is offline nilsomat  Germany
diyAudio Member
Join Date: Dec 2005
Location: Berlin
Hello everybody,
very nice thread, and long overdue i would say.
I can second that the Peerless SLS-12 is indeed a great driver for that design, and it performs beautifully in my ripole.
I will post some more information soon.
  Reply With Quote
Old 20th September 2006, 04:11 PM   #28
moray james is offline moray james  Canada
diyAudio Member
Join Date: Aug 2003
Location: Calgary on the Bow
Hope this attached data sheet on the 30 WN 380 RL/8opens. If not here is a copy of the data on this driver. Regards Moray James.

30-cm-Tieftonlautsprecher with very hard, conical paper diaphragm.
50-mm-Schwingspule, 4 lagig. Large stroke reserve (large mechanical stroke).
Ventilated magnetic system.
Ideal low clay/tone driver. Been suitable for bass reflex housings or closed volumes
(e.g. as Subwoofer, actively entzerrt).

Chassis data:
External dimensions: 308 mm Schw. - reel Ø: 40 mm
Installation dimension: 297 mm Schw. - reeling height 14 mm
Depth: 128.6 mm Schw. - spulen-Träger

Front. Material: Air gap height mm
Basket material: Air gap filling:

Diaphragm type: Magnet Ø: mm
Diaphragm Sicke: conical Magnet height: mm
Diaphragm material: Paper Magnet weight g
Dustcap material: Magnet Ind. T

Thiele Small parameter:
Resonance fms: 21 Cycles per second Indulgence Cms mm/N
mechanical. Quality Qms: 2.3 moved mass Mms: 53 g
electrical quality Qes: 0.25 mechanical. Absorption Rms: kg/s ¹
Total quality Qts: 0.23 Diaphragm stroke Xmax: mm
A-volume Vas: 400 Litre Force factor Bl: 12.7 N/A

DC resistance RH: Ohm Diaphragm Ø MD:
Inductance Le: mH Diaphragm surface Sd: 513 cm ²
Electrical absorption Res: Ohm Max. separation frequency. fmax: 1 kHz

Efficiency Nref: % Nominal sound pressure SPL: 93 railways

Product folder (English): Pdf Download (33 KB)
moray james
  Reply With Quote
Old 20th September 2006, 04:31 PM   #29
soundcheck is offline soundcheck  Germany
diyAudio Member
Join Date: Mar 2005
Location: DUS
Hi folks.

I finished my ripoles using 4* BD15 drivers of Bert Doppenberg some time ago.

These are 16R drivers with an efficiency of 97db each!

This a much higher efficiency than you're discussing here!

I am more than happy with them.

Read this:


  Reply With Quote
Old 20th September 2006, 05:26 PM   #30
qi is offline qi
diyAudio Member
Join Date: Oct 2003
Location: .
Originally posted by MJK
I don't think that any of the current worksheets will do the job. But it should not be too difficult to configure a worksheet that would do all of these and a few more, basically a driver loaded front and back with quarter wave pipes. Just a matter of finding the time and determining if there is enough interest to justify spending that time. Definitely interesting enclosure designs.
Hi Martin

I am sending you my money today.

Nothing speaks more loudly than MOOLA.

I am hoping others following this thread shall follow suit...
  Reply With Quote


Drivers /  parameters for ripole subsHide 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
TS parameters and specs for these drivers??? Bull Multi-Way 1 9th March 2011 01:15 PM
T/S parameters for horn drivers buggsson Multi-Way 7 25th March 2008 09:53 AM
Parameters for drivers iwahn Subwoofers 0 20th June 2007 10:13 PM
FS: horn subs, drivers, 'regular' subwoofer drivers John Sheerin Swap Meet 0 2nd August 2004 12:33 AM
T/S parameters of JBSystems drivers sstoiana Multi-Way 1 30th September 2003 09:11 PM

New To Site? Need Help?

All times are GMT. The time now is 01:48 PM.

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