Ripole sub project

Jazzman53 · « **on:** 12 Jan 2011, 01:42 am »

Hello All,

I'm not sure which circle is appropriate for my new project thread but since Ripoles are essentially a folded dipole, I figure they are are closer to OB's than boxes (even though there is a box, of sorts). Anyway, I have some issues to workout before I start the build and I welcome your opinions and recommendations!

I've just ordered (4) Peerless SLS 12's from Parts Express and I've started drawing up an "M" profile Ripole box design similar to this one: http://www.rstaudio.de/Subwoofer/sub_en.html

I plan to use these subs for music playback, primarily; supplementing the 10" transmission line woofers in my hybrid electrostats. The SLS's will be wired parallel and driven thru active crossover with a Carver TFM-42 (375w/ch) power amp.

I know that Ripoles are inefficient but I like their dipole radiation pattern, which should excite fewer room modes, and I like their ultra-compact size too.

Even though I will be using an active crossover, I'm thinking I may want to use a passive notch filter to tamp down the characteristic resonant peak anticipated to occur somewhere between 200-300hz, rather than trying to EQ it out upstream (?) I suppose if I select a low enought crossover point with a steep enough slope, the 200-300hz resonance probably wouldn't be an issue.
Opinions on that are appreciated

If a passive notch filter is deemed desirable, I'm not at all clear on how to go about making one. Recommendations on that are appreciated too

Since my current DBX 223 crossover is a 2-way with no sub out, I will need a new crossover for this project. Recommendations for a crossover, frequency and slope are appreciated!

I will post some pics once I get rolling.

thanks,
Charlie

David Weil · « **Reply #1 on:** 27 Jan 2011, 08:58 pm »

You will need a notch filter so that your crossover can work in a predictable way, because that boost at 200-300 Hz can easily be 20 dB. With an active crossover it makes sense to integrate the notch filter into it. The components are much smaller and less expensive. The price is an even bigger advantage, if you still need to experiment.

For a passive solution a 10 mH inductor in parallel with a 47 µF capacitor in series with each woofer coil should be a good starting point. When you see the prices for inductors capable of the necessary currents you will see why you don't want to experiment too much with such a passive solution.

For an active solution the simulated inductor is what you are looking for.

ondesx · « **Reply #2 on:** 27 Jan 2011, 11:01 pm »

Hi Jazzman53,

I'm building the same couple of ripoles with Dayton subs !...

For the XO it seems that the cheapest solution is the Behringer DCX.

For the peak perhaps you've to measure before any compensation...

Jazzman53 · « **Reply #3 on:** 2 Feb 2011, 02:47 am »

Hello All,
I'm almost done building my new Ripole subs and I want to thank those of you who've taken the time to help me with this project. I'm using (4) Peerless SLS 12's and a dedicated Carver TFM-42 for power. I completed the boxes today but I still have to decide on the crossover and EQ'ing and then buy what's needed.

Here's some photos: http://jazzman-esl-page.blogspot.com/2011/01/ripole-subs-are-underway.html

In hindsight, I wish I had waited a while and learned more about Ripoles before starting the build, as I have since received much good advice for optimizing their performance but I was already too far along in the build to take full advantage of it. Still, the chambers and openings do meet the minimums recommended in one of Rudolf's threads (on the DIY Audio Forum) so I'm hopeful and confident that these subs will sound pretty good if I get the crossover and EQ'ing right.

My main speakers are hybrid electrostats with 10" transmission line bass and my current active crossover doesn't have a sub out so I will have to buy another crossover. I've already gotten some good advice but I can always use more so please let me hear your opinions on a crossover, slope and EQ'ing to best blend my new subs with my main speakers. Thanks everyone!

Badwater · « **Reply #4 on:** 2 Feb 2011, 10:29 pm »

very nice work. Anxious to hear your impressions.

matevana · « **Reply #5 on:** 3 Feb 2011, 12:57 pm »

Here's some photos: http://jazzman-esl-page.blogspot.com/2011/01/ripole-subs-are-underway.html

Nice work! I tried a quick mock-up of a ripole when they first started getting press, with a pair of Peerless 10" XXLS nomex drivers. Was impressed with the additional extension, but it also seemed to put a veil over the upper bass register that I loved with the same drivers in a traditional OB. As an example, Brian Brombergs playing didnt have the same punch or authority, albeit the response may have been a bit lower. No matter what I did, (xo point, eq, notching) I couldnt restore the presentation, so I gave up. I was using a dBX 234 3-way x/o with a Behringer DEQ2496 for EQ plus notching.

You may wish to take a look at the BBE max-x3 crossover. You can get 'em pretty cheap on eBay and the additional "exciter" function may prove to be useful. The lo contour control on the maximizer affects the 50Hz range and may help with some phase/alignment issues with your sub. I've since replaced my Behringer DEQ with a dBX 2231 analog EQ and am much happier with the overall sound. Something still to be said for high quality, analog devices.

Ed

Jazzman53 · « **Reply #6 on:** 3 Feb 2011, 04:49 pm »

Thanks for the tip on the BBE Crossover... I will look for one on Ebay. I just got the Behringer DEQ and I'm still tweaking with it... lots of neat functions but the jury is still out on it's sound, which so far sounds rather "clinical". Right now I'm stumped on configuring a notch filter, as I'm not versed in electronics.

matevana · « **Reply #7 on:** 3 Feb 2011, 08:57 pm »

Quote from: Jazzman53 on 3 Feb 2011, 04:49 pm

Thanks for the tip on the BBE Crossover... I will look for one on Ebay. I just got the Behringer DEQ and I'm still tweaking with it... lots of neat functions but the jury is still out on it's sound, which so far sounds rather "clinical". Right now I'm stumped on configuring a notch filter, as I'm not versed in electronics.

You can easily use the parametric function on the DEQ to notch-out selected frequencies very effectively, making the slope as steep or gradual as you need it. The utility of the DEQ is amazing, especially for the price. That being said, I spent many hours A/B ing the Behringer vs. the dBX 2231 analog unit, only to find that I much preferred the dBX for SQ.

I'm really interested in your listening impressions of your ripole. I really like the Peerless SLS series, not just for their cost, but also their relatively low MMS specs. You should get very llittle baffle excitation, compared to other drivers with similar excursion. The integration with your electrostatics shouldnt be too painful.

pjchappy · « **Reply #8 on:** 3 Feb 2011, 10:32 pm »

Quote from: matevana on 3 Feb 2011, 08:57 pm

You can easily use the parametric function on the DEQ to notch-out selected frequencies very effectively, making the slope as steep or gradual as you need it. The utility of the DEQ is amazing, especially for the price. That being said, I spent many hours A/B ing the Behringer vs. the dBX 2231 analog unit, only to find that I much preferred the dBX for SQ.

I'm really interested in your listening impressions of your ripole. I really like the Peerless SLS series, not just for their cost, but also their relatively low MMS specs. You should get very llittle baffle excitation, compared to other drivers with similar excursion. The integration with your electrostatics shouldnt be too painful.

People should also consider the miniDSP in-a-box. Has single ended and balanced input options, too. (I use one) http://www.minidsp.com/

Jazzman53 · « **Reply #9 on:** 5 Feb 2011, 02:44 am »

Quote from: ondesx on 27 Jan 2011, 11:01 pm

Hi Jazzman53,

I'm building the same couple of ripoles with Dayton subs !...

For the XO it seems that the cheapest solution is the Behringer DCX.

For the peak perhaps you've to measure before any compensation...

The DCX definitely isn't the cheapest solution but, what the hell, screw the budget--- I just ordered me a DCX. I figure with all that fancy shit I won't be needing a passive filter anyway.

gnnett · « **Reply #10 on:** 5 Feb 2011, 04:07 am »

Will watch with interest as have 1+1's which might benefit from some assistance below 50Hz.

Good luck.

Grantn

jk@home · « **Reply #11 on:** 5 Feb 2011, 02:26 pm »

Quote from: Jazzman53 on 5 Feb 2011, 02:44 am

The DCX definitely isn't the cheapest solution but, what the hell, screw the budget--- I just ordered me a DCX. I figure with all that fancy shit I won't be needing a passive filter anyway.

Unless you all ready know this

If you can, make up a remote serial cable, so that you can adjust the DCX "real time" from a PC/laptop.

If the same PC/laptop has something like REW installed. makes it real easy to measure and adjust the settings you need.

Jazzman53 · « **Reply #12 on:** 9 Feb 2011, 09:42 am »

I would prefer to do the computer hookup but I checked the Behringer website and for Windows OS I only see downloads for XP and 2000 and my laptop runs Vista.

JohnR · « **Reply #13 on:** 9 Feb 2011, 09:54 am »

Nice build

I'm not at all clear on how mounting two of them like that is any different to a Linkwitz "W" enclosure e.g. as used in the Phoenix. I'm just wondering.

Re crossover - well, a miniDSP 2x4 is $125 and postage. I've been really pleased with these little units, I do think you will save yourself some time and trouble. According to this page the interface is Vista compatible. The gain structure/levels (0.9V) seem generally fairly compatible with domestic equipment. Here are a couple of articles I wrote that will give you an idea of capabilities (the pure dipole bass subsystem article is on the way but will use the balanced module):

http://www.hifizine.com/2010/09/subwoofer-equalization-and-integration-with-the-minidsp-2x4/
http://www.hifizine.com/2010/12/prototyping-4-way-open-baffle-speaker-with-the-minidsp-2x4/

criv911 · « **Reply #14 on:** 20 Mar 2011, 04:48 pm »

I am interested in trying on of these subs with my magnepans. I have an old radio shack 12" sub that I can cannibalize. I have no idea what the specs are on the driver. If I were to experiment with this driver would it give me a reasonable representation of the kind of sound I could expect. I realize that it"s a shot in the dark, but if it gives me the flavor of what a ripole can do I would then go and buy the right driver.

THWO · « **Reply #15 on:** 26 Mar 2011, 12:08 am »

The developer or at least one of the devbelopers of this dipole concept is Axel Ridtahler, therefore the name "RiPol". Altough he has been developing and trying to sell his own products, he is ready to assist DIY-builders in realizing their own projects. If still valid, he can be adressed under

R_axel@web.de

May be he has already plans for a crossover- and frequency correction circuit for exactly your Peerless speakers. He may ask for a handful Euros for an advice - in case he has one - (as he has to make a living on that), but a preliminary inquiry cannot harm and my possibly bring you new insights. - Just an idea...

Best success with your fine project and congratulation to your very fine built!

Regards from Frankfurt / Germany,
Till

Bob in St. Louis · « **Reply #16 on:** 19 Apr 2011, 12:58 am »

Nice build Charlie, well done Sir. The structure looks very solid.

I'll be building one of these soon (with different drivers). Any updates thoughts, ideas, suggestions from you since your build?

Bob

Jazzman53 · « **Reply #17 on:** 19 Apr 2011, 02:08 am »

Quote from: Bob in St. Louis on 19 Apr 2011, 12:58 am

Nice build Charlie, well done Sir. The structure looks very solid.

I'll be building one of these soon (with different drivers). Any updates thoughts, ideas, suggestions from you since your build?

Bob

Hi Bob,
I'm pleased with mine as they are; although I'm not really utilizing all that they are capable of, since I'm using them purely in the sub bass region (below 50hz with a 48db/oct crossover slope). For mid bass I'm using the transmission line woofers in my hybrid electrostats exclusively, which have a really gorgeous tone. Using the ripoles in this manner, I often feel their presence but seldom actually hear them unless I put on a tune that has some really low bass content. For example, this evening I played "Flight of the Cosmic Hippo" by Bela Fleck and (OMG) the ultra low bass from the ripoles was truly astounding.

Sadly, the math and modeling of Ripoles is beyond me so I merely followed some generic guideline gleaned from threads on the DIY Audio Forum and I have a DSP crossover and EQ to help out. The guys I would ask for advice are Rudolf and Calvin over at the DIY Audio Forum.... those guys seem to have a good grasp of Ripole theory.

good luck with your project!
Charlie

Bob in St. Louis · « **Reply #18 on:** 19 Apr 2011, 12:52 pm »

Yea, that "Cosmic Hippo" track is obscene for LF.

Insanity at it's best!

I'll peek over at DIY, thanks for the heads-up Charlie.

By the way, your blog is great. Well organized, clean and informative. Nicely put together.

Bob

Jazzman53 · « **Reply #19 on:** 8 May 2011, 06:04 pm »

Thanks Bob,
I think I get as big a kick out of the Jazzman's ESL Page and receiving emails from all over the world as I got from building those speakers.

Yes, Flight of the Cosmic Hippo is a real workout for a subwoofer. A few weeks ago I attended the premier performance of Bela Fleck with the Marcus Roberts Trio at a small venue in Savannah... 2nd row center, about 8 feet from the stage... the whole audience was completely floored. Even the musicians couldn't believe the magic that happened there. Fleck can play any genre with equal aplomb. BTW, I used to live in St. Louis (1975-78)... great town!
Charlie