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DBog 17th August 2012 06:27 PM

Need help with ripole
Need help with a ripole (to use in a hybrid ESL)

I am in the DIY for some time. As I live in Brazil, we have very limited options of quality drivers for an affordable price. I am a big fan of the ESL qualities, but I am pretty aware of the limitations of this design. Considering this one of the arragements that mostly attracted my attention was an hybrid design with an ESL handling mid-bass and high frequencies and normal (sub) woofers managing the low end.

I was looking for design that could pair with ESLs to handle low frequencies and I end up choosing woofers in a cardioid restricted dipole (ripole) arrangement. I did some research but unfortunately there are very few sources of information about ripoles online. So I am asking for some advice from the most experienced members of this community. I pick some of the information pieces available and ended up with the following design:

NAR Audio 12” Subwoofer 1204-SW-2
Qts= 0.841
Xmax= 7,25mm
Fo=22.153 Hz
Sd=551.55 cm²
Revc=3.600 Ohm
Levc=1.690m H
Md=44.000 g
BL=8.066 T•M
Qms= 6.715
Qes= 0.961
No= 0.195 %
SPLo= 84.9 dB
Vas=178.658 l
Cms=413.584u M/N
Mms=124.794 g
Mmd=117.346m Kg

Ripole box dimensions:
Back port: 2 x 15cm x 10cm = 300cm²
Front port: 15cm x 20cm = 300cm²
Internal dimensions of the woofer baffles: 15cm x 15cm
MDF with 2.5cm thickness

Woofers arranged in series and a passive crossover around 100hz.

My assumptions are:
Linear (as much as possible) from 20 to 20Khz
Low SPL is not a problem (as I plan to use ESLs)
Clear and well defined bass (specially aiming jazz and progressive music)
Do not want a wall-shaker but want to clearly “notice” all the lows of an acoustic bass :D
I will be using an old-style tube amp

Any suggestions? :worship:


elac310 19th August 2012 12:08 AM


I, too, have spent some time studying the ripole concept and I just completed a big subwoofer system (that would fit in with my high sensitivity horn system).

In your place, even if ESL have a low sensitivity, I would go for somewhat larger speakers (say 15" or 18") if you are really looking for the lowest frequencies and some decent level. If you use a dedicated amp and electronic crossover including maybe also some equalizing possibilities, that would give you much more flexibility to adjust the sound level to your taste. I was given the same advice by others a few months back, and I do not regret following this approach.

As regards the enclosure, ripoles use in principle a different load for the front and for the back side of the speaker cones. If you do a google search for pictures with "ripole" (try also "ripol" and you get more from German DIYer projects since the concept is quite popular there) you will see that one vent is normally larger than the other (in practice, it's usually the back side vent).

So much for RIpoles. I take it that you've also looked at the various W-, N-, U-, H- and S-DIpoles.

Good luck.


jacq. 19th August 2012 01:46 AM

Make it easy on yourself, get a mini DSP and a 60w/ch to 150w/ch second hand stereo transistor amp and follow infos on LINKWITZLAB.COM for dipole subs;). You will not regret it.

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