Hi,
the Alpha is just a cheap driver. I wouldn´t recommend it for the small folded Baffle dipoles. The excursion limit is rather small. If the parameters on the website are true You could expect at least ~5Hz of reduction in Fs. As MJ pointed outthere are other drivers on the website that look far more promising than the Alpha....costier though.
jauu
Calvin
the Alpha is just a cheap driver. I wouldn´t recommend it for the small folded Baffle dipoles. The excursion limit is rather small. If the parameters on the website are true You could expect at least ~5Hz of reduction in Fs. As MJ pointed outthere are other drivers on the website that look far more promising than the Alpha....costier though.
jauu
Calvin
Hi and thank you very much for warning .
A few days ago I found s/h, but in very good condition 2 pc. Electro Voice woofers, model Force 15. Basic parameters are:
Fs - 40Hz
Qts - 0,51
Vas - 297,4 liter
Xmax - 3,3 mm
Sensitivity - 100 dB
Power rating 150 Watts
more info on http://www.usspeaker.com/ev force15-1.htm
I am just wonder whether maybe this driver could be good in ripole. The guy is asking 200 euros/pair, well not cheap for s/h, but I could partly trade in some of my stuff. Sensitivity is great, but again Xmax and Fs so, so.
Any opinions will be much appreciated. Thank you in advance.
A few days ago I found s/h, but in very good condition 2 pc. Electro Voice woofers, model Force 15. Basic parameters are:
Fs - 40Hz
Qts - 0,51
Vas - 297,4 liter
Xmax - 3,3 mm
Sensitivity - 100 dB
Power rating 150 Watts
more info on http://www.usspeaker.com/ev force15-1.htm
I am just wonder whether maybe this driver could be good in ripole. The guy is asking 200 euros/pair, well not cheap for s/h, but I could partly trade in some of my stuff. Sensitivity is great, but again Xmax and Fs so, so.
Any opinions will be much appreciated. Thank you in advance.
It is really sometimes funny, I checked this german site a several times and just now realized the driver, Axel Ridtahler actually recomends for ripole, or as it is said in the text:
Quote The following bass drivers are regarded by him as particularly suited. unquote
http://www.lautsprechershop.de/hifi/index_en.htm?/hifi/ripol_en.htm
So, the target parameters for ripole driver should be probably close to this one
• Power handling (continuous/programme) = 100/200 W
• Resonance frequency fs = 29 Hz
• Impedance R = 4 Ohm
• SPL = 87 dB (2.83V; 1m)
• DC resistance Re = 3.5 Ohm
• Electro-magnetic force factor BL = 16 N/A
• Voice coil inductance L = 2.5 mH
• Effective piston radiating area Sd = 531 cm2
• Effective mechanical mass incl. air load 196 g
• Equivalent volume of compliance Vas = 61 l
• Q due to overall loss Qts = 0.42 (Qms=6.63, Qes=0.45)
• Linear excursion xlin = +/- 6 mm
• Cut-out diameter d = 287 mm
• Overall diameter d = 311 mm
Quote The following bass drivers are regarded by him as particularly suited. unquote
http://www.lautsprechershop.de/hifi/index_en.htm?/hifi/ripol_en.htm
So, the target parameters for ripole driver should be probably close to this one
• Power handling (continuous/programme) = 100/200 W
• Resonance frequency fs = 29 Hz
• Impedance R = 4 Ohm
• SPL = 87 dB (2.83V; 1m)
• DC resistance Re = 3.5 Ohm
• Electro-magnetic force factor BL = 16 N/A
• Voice coil inductance L = 2.5 mH
• Effective piston radiating area Sd = 531 cm2
• Effective mechanical mass incl. air load 196 g
• Equivalent volume of compliance Vas = 61 l
• Q due to overall loss Qts = 0.42 (Qms=6.63, Qes=0.45)
• Linear excursion xlin = +/- 6 mm
• Cut-out diameter d = 287 mm
• Overall diameter d = 311 mm
Hi,
the conclusion is wrong.
If You´d know the circumstances of how the linked project came to life You´d know better The chromed pole plate and low height of the driver were two of the major points in the decision process 
Anyway....there is not such a thing as a universally perfect set of parameters. For example I prefer a rather highish Qt for smaller drivers, and a lower value for bigger drivers. If You use a bigger casing like the Linkwitz type lower Fs and Qm can be helpful. With the ripol-type a elevated Fs and higher value of Qm is preferable.
I´ve got different experiences than Zobsky and have probably seen and heard nearly every dipole Axel has built, among those were examples featuring drivers with Qts>1. High Qt-drivers can work excellent in ripoles. If they don´t, I assume that something else didn´t match.
The listed values of the 12" driver are so far ok and the ripol works well with them.
jauu
Calvin
the conclusion is wrong.
If You´d know the circumstances of how the linked project came to life You´d know better
The chromed pole plate and low height of the driver were two of the major points in the decision process Anyway....there is not such a thing as a universally perfect set of parameters. For example I prefer a rather highish Qt for smaller drivers, and a lower value for bigger drivers. If You use a bigger casing like the Linkwitz type lower Fs and Qm can be helpful. With the ripol-type a elevated Fs and higher value of Qm is preferable.
I´ve got different experiences than Zobsky and have probably seen and heard nearly every dipole Axel has built, among those were examples featuring drivers with Qts>1. High Qt-drivers can work excellent in ripoles. If they don´t, I assume that something else didn´t match.
The listed values of the 12" driver are so far ok and the ripol works well with them.
jauu
Calvin
Zobsky -
Just happened to open right at your last post.
In a jist, why not? I could use being saved from another useless experiment. Too much coloration?
Space constraints had me thinking about this with higher QTS drivers.
Plannin a move so thinking to eliminate IB and other thoughts have me considering simple single driver scoop horn.
Thanks - Bluto
Just happened to open right at your last post.
In a jist, why not? I could use being saved from another useless experiment. Too much coloration?
Space constraints had me thinking about this with higher QTS drivers.
Plannin a move so thinking to eliminate IB and other thoughts have me considering simple single driver scoop horn.
Thanks - Bluto
Hi all !
you guys seem to know a lot about Ripole's
What cabinet dimentions do you advise for cheap 8" drivers like this:
Revc=7.9 Ohm
Fo=47.634Hz
Sd=15.416msqM
BL=3.851TM
Qms=4.621
Qes1.291
Qts=1.009
No=0.376%
SPLo=87.8dB
Vas=46.507mcuM
Cms=1.378mM/N
krm=170.017uOhm
Erm=1.003
Mms=8.101g
Mmd=7.000mkg
Kxm=2.701mH
Exm=0.792
Qts is a bit high, but I understand that might even help keeping it
passive (no eq needed ?)
Cheers,
Empee
you guys seem to know a lot about Ripole's
What cabinet dimentions do you advise for cheap 8" drivers like this:
Revc=7.9 Ohm
Fo=47.634Hz
Sd=15.416msqM
BL=3.851TM
Qms=4.621
Qes1.291
Qts=1.009
No=0.376%
SPLo=87.8dB
Vas=46.507mcuM
Cms=1.378mM/N
krm=170.017uOhm
Erm=1.003
Mms=8.101g
Mmd=7.000mkg
Kxm=2.701mH
Exm=0.792
Qts is a bit high, but I understand that might even help keeping it
passive (no eq needed ?)
Cheers,
Empee
Empee,
since the Fo of that driver is quite high for a subwoofer, you want to lower it as much as possible. This can be achieved by making the front and back channel area really small. Try a front channel area of 1/4 Sd (for each driver) or even 1/5 Sd. Back channel area as small as the basket allows.
A small area will lower the sensitivity of the subwoofer and raise the lambda/4 resonance peak of the channel. So while you may not need to EQ the 6 dB/oct dipole loss, you certainly need a notch filter for that resonance peak. It could be up to 15 dB tall!
Height and depth of the cabinet should be just large enough to acommodate the drivers. You will need a bunch of those drivers to get decent SPL. I would reckon 8+ at least.
since the Fo of that driver is quite high for a subwoofer, you want to lower it as much as possible. This can be achieved by making the front and back channel area really small. Try a front channel area of 1/4 Sd (for each driver) or even 1/5 Sd. Back channel area as small as the basket allows.
A small area will lower the sensitivity of the subwoofer and raise the lambda/4 resonance peak of the channel. So while you may not need to EQ the 6 dB/oct dipole loss, you certainly need a notch filter for that resonance peak. It could be up to 15 dB tall!
Height and depth of the cabinet should be just large enough to acommodate the drivers. You will need a bunch of those drivers to get decent SPL. I would reckon 8+ at least.
What do you think of these for Ripole?
http://www.iplacoustics.co.uk/drive_unit_sale.htm
W-type as built in this thread
http://www.iplacoustics.co.uk/drive_unit_sale.htm
W-type as built in this thread
Ok, I built a quick and nasty Ripole with a pair of Hi-Vi D10G's (I shall name it the "Ripole-mess" due to it's low construction values ). No maths used, just fitted it together with whatever was convenient. Sorry, no pics as camera was elsewhere.
Got to listen for a couple of hours this morning, actually quite impressed. Not as inefficient as I expected, these 10" drivers in a W profile could create quite a lot of output! Didn't actually get them near full excursion today. Never got the filter sorted though to correct for baffle loss, so I had it up louder than it should have been in relation to the mains making higher bass ranges excessively loud.
Kick drums sound great, transient response is generally very good. Not as audible outside of the room as a typical closed/ported speaker (this is my first OB experiment). Will an OB speaker excite less room nodes too? I couldn't tell for sure as the crossover was not ideal and as mentioned I didn't have the corrective filter in place.
What do you think of using drivers like these:
http://cgi.ebay.ph/ws/eBayISAPI.dll?ViewItem&item=260280390035
Sorry, manufacturers page doesn't seem to be working
They are also available in 15". Have decent Xmax and are cheap enough to build 2 W-frame subs, or 3 if desired, have heard it is advantageous to have multiple subs to help control room nodes.
Is there any special criteria for designing Ripoles yet? Are ideal driver parameters known?
). No maths used, just fitted it together with whatever was convenient. Sorry, no pics as camera was elsewhere.Got to listen for a couple of hours this morning, actually quite impressed. Not as inefficient as I expected, these 10" drivers in a W profile could create quite a lot of output! Didn't actually get them near full excursion today. Never got the filter sorted though to correct for baffle loss, so I had it up louder than it should have been in relation to the mains making higher bass ranges excessively loud.
Kick drums sound great, transient response is generally very good. Not as audible outside of the room as a typical closed/ported speaker (this is my first OB experiment). Will an OB speaker excite less room nodes too? I couldn't tell for sure as the crossover was not ideal and as mentioned I didn't have the corrective filter in place.
What do you think of using drivers like these:
http://cgi.ebay.ph/ws/eBayISAPI.dll?ViewItem&item=260280390035
Sorry, manufacturers page doesn't seem to be working
They are also available in 15". Have decent Xmax and are cheap enough to build 2 W-frame subs, or 3 if desired, have heard it is advantageous to have multiple subs to help control room nodes.
Is there any special criteria for designing Ripoles yet? Are ideal driver parameters known?
Ok, I have managed to get a couple of pictures of my sub. The more I read the more I think that what I have built is in fact a W-Profile OB speaker rather than a Ripole since the chambers are relatively large. The width of the front opening is 130mm, the rear openings are around 100mm each.
These drivers are quite shallow but it would be impossible to allow the magnet system to protrude due to thier construction, so the rear chamber has been constructed to accomodate.
I can't find much information relating to W-Profile subs. Is there an optimum sizing and ratio of sizes for the openings? Presumably a W-Profile sub requires 6db compensation as other types of OB do (H and U frames etc) whereas a Ripole claims not to require so much. Listening to this sub it does sound better with compensation, otherwise higher bass ranges are too loud compared to low kick drums etc.
Any help appreciated! I like what I'm hearing but want refinement and understanding!
These drivers are quite shallow but it would be impossible to allow the magnet system to protrude due to thier construction, so the rear chamber has been constructed to accomodate.
I can't find much information relating to W-Profile subs. Is there an optimum sizing and ratio of sizes for the openings? Presumably a W-Profile sub requires 6db compensation as other types of OB do (H and U frames etc) whereas a Ripole claims not to require so much. Listening to this sub it does sound better with compensation, otherwise higher bass ranges are too loud compared to low kick drums etc.
Any help appreciated! I like what I'm hearing but want refinement and understanding!
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
How much did you block off any pole vent?
What is the Sd of the drivers? Could not find it in the specifications at PE.
Did you make the front opening area anywhere near Sd/2? It does not look like it in your picture. But hard to guess.
Don´t bother about the area of the back openings. I see that the basket construction would make it too complicated to make it smaller. It´s less relevant than many people think.
How did you manage the notch filter for the resonance?
What is the Sd of the drivers? Could not find it in the specifications at PE.
Did you make the front opening area anywhere near Sd/2? It does not look like it in your picture. But hard to guess.
Don´t bother about the area of the back openings. I see that the basket construction would make it too complicated to make it smaller. It´s less relevant than many people think.
How did you manage the notch filter for the resonance?
Hi, thanks for replying
Full driver specs are here:
http://www.swanspeaker.com/product/htm/view.asp?id=64
The pole vent is blocked off a bit I guess. From the "grille" it is probably only about 1cm. I doubt its an issue in terms of cooling, these drivers have big 4" voice coils and in this configuration are xmax limited way before thier 150W power handling. The vent makes noises at the highest levels (could be heard on massive attack - angel, where the large transient kick sound is very solo) but this is an artifact of the driver and it does it outside of any box too
Sd is 430cm^2; your suggestion is to make the front opening half of this size? Say if it were 32cm tall (roughly), it should be 6.7cm wide (as opposed to 13cm)? This would make it a Ripole rather than whatever else it is at the moment . Creates a fair pressure as it is.
I haven't actually got notch filtering yet, probably need to measure response to find the point? I have merely implemented a 6db lowpass at about 22hz to raise the low frequency level in respect (its all very "test" stage at the moment!). Crossover is 110hz I think, just something I had ready made, is all active
Full driver specs are here:
http://www.swanspeaker.com/product/htm/view.asp?id=64
The pole vent is blocked off a bit I guess. From the "grille" it is probably only about 1cm. I doubt its an issue in terms of cooling, these drivers have big 4" voice coils and in this configuration are xmax limited way before thier 150W power handling. The vent makes noises at the highest levels (could be heard on massive attack - angel, where the large transient kick sound is very solo) but this is an artifact of the driver and it does it outside of any box too
Sd is 430cm^2; your suggestion is to make the front opening half of this size? Say if it were 32cm tall (roughly), it should be 6.7cm wide (as opposed to 13cm)? This would make it a Ripole rather than whatever else it is at the moment
. Creates a fair pressure as it is.I haven't actually got notch filtering yet, probably need to measure response to find the point? I have merely implemented a 6db lowpass at about 22hz to raise the low frequency level in respect (its all very "test" stage at the moment!). Crossover is 110hz I think, just something I had ready made, is all active
I did not think of the heat, but the air flow from the vent. Just to make shure it is not obstructed too much.Dr.EM said:
So NOT opening the wall for the magnet might even have been the better strategy
Yes, that was, what I was thinking. But if you get sufficient bass as is, than there is no need to narrow the opening.
So I don´t see any reason to refine anything, except getting some measurement and looking for the appropriate EQ - and obviously - getting the optics of the enclosure right.
BTW: There really is no single/universal optimum size or proportion for those W frames. By narrowing the front opening you just change efficiency for lower bass . At the same time the resonance peak will rise. It´s up to you to decide where your personal optimum is.
Great, that helps a lot
The front opening is conveniently just about the minimum size where I can still install the 2 drivers from the front, so the enclosure can all be glued (allen bolts essential!). Would probably build from either 25mm MDF or perhaps better 12mm MDF+12mm Ply laminate; could add the bars/spokes accross the openings as is popular too. Aesthetically would probably have grille material around all sides and some sort of wood finish top and bottom, although the basket is quite attractive on these drivers imo.
Really would need 3 units (6 drivers) to get enough output for a medium living room I feel. Fairly costly unfortunately but with just one I get the motor noises at high levels on music where it isn't "covered". Any ideas on how positioning 3 subs can help reduce room node problems? Is that true, I have heard it said and it makes some sense.
Other options might be to add a sub-sub wooferconfused: ) to reduce excursion of these dipoles, just to cover below about 30hz. Perhaps a low tuned TL with a low fs driver; bandpass would be great but none work in this range that I have found. Means more amplifiers and crossovers though and 5 way is getting a bit crazy
The front opening is conveniently just about the minimum size where I can still install the 2 drivers from the front, so the enclosure can all be glued (allen bolts essential!). Would probably build from either 25mm MDF or perhaps better 12mm MDF+12mm Ply laminate; could add the bars/spokes accross the openings as is popular too. Aesthetically would probably have grille material around all sides and some sort of wood finish top and bottom, although the basket is quite attractive on these drivers imo.
Really would need 3 units (6 drivers) to get enough output for a medium living room I feel. Fairly costly unfortunately but with just one I get the motor noises at high levels on music where it isn't "covered". Any ideas on how positioning 3 subs can help reduce room node problems? Is that true, I have heard it said and it makes some sense.
Other options might be to add a sub-sub woofer
confused: ) to reduce excursion of these dipoles, just to cover below about 30hz. Perhaps a low tuned TL with a low fs driver; bandpass would be great but none work in this range that I have found. Means more amplifiers and crossovers though and 5 way is getting a bit crazy
Dr.EM said:Great, that helps a lot
It made sense to me too when Earl Geddes explained his method with 3 subs in the "Nathan" thread. How about building another W frame and then a monopole frame with a bigger single driver for some punch down low? I have not tried it myself yet, but mixing dipole and monopole may give you the best of both worlds. I sent you a PM regarding more info.
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