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Thread: Ripole Subs
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November 27, 2021, 12:43 AM #1
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- Nov 2021
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- Savannah, GA
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- 33
Ripole Subs
I've just finished building a pair of Ripole subs, which turned out very nice.
The Ripole design was patented by German speaker designer Axel Ridtahler. Conceptually; it's a dipole speaker with its baffle folded around a pair of opposing drivers in push-push configuration. The name "Ripole" refers to a Ridtahler dipole.
Ripoles have a cardioid radiation pattern which tends not to excite the room's resonance modes, and my pair blend quite well with my DIY ESL's.
The woofer cases are 3/4 AA red oak plywood with quarter-round oak moldings along the box edges.
The center C-section is cut from 7/8" white oak planks, stained a contrasting color and aligned to the woofer cases with dowels. The three-part assembly bolts together with (4) 1/4-20 all-thread rods and button-head cap nuts.
The opposing woofers are 12" Peerless SLS's wired in parallel and in same phase (i.e. push-push). Allowing the woofer magnets to protrude thru the side baffles is a unique feature which makes the design very compact.
Another unique feature is that the acoustic impedance of chambers significantly lowers the woofers' resonant frequency (f/s); allowing the speaker to play about 10Hz lower than the woofers' f/s in free air.
The build was a lot of work but they are unique and I really like their compact size and clean, unobtrusive sound.
The bass notes just seem to rise up from nowhere and recede back to nowhere-- completely un-localizable.
I have a CAD drawing if anyone is interested.
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November 28, 2021, 09:25 AM #2
- Join Date
- May 2015
- Posts
- 100
Re: Ripole Subs
Absolute beautiful. Congratulations. How low do you think your subwoofer can go?
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November 28, 2021, 10:27 AM #3
Re: Ripole Subs
Glad to see you still at it Jazzman .. !
Would you happen to have any measurements, would love to see impedance mag and phase along with FR response ..! !!
Regards* An Audiophile is only as old as his latest Class D incarnation *
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November 28, 2021, 10:39 AM #4
Re: Ripole Subs
Great woodworking skills!
Marty
Aurender N20 / SonicTransporter i7 / Roon
MSB Premier
Constellation Inspiration Preamp 1.0 / Mono 1.0
Dynaudio Confidence 50 / SVS SB13 Ultra
PS Audio Powerplant 15
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November 28, 2021, 11:04 AM #5
- Join Date
- Nov 2021
- Location
- Savannah, GA
- Posts
- 33
Re: Ripole Subs
That's a difficult question to answer. I can give you a pretty good estimate, but I haven't measured that directly.
I have my DBX Venu 360 crossover applying a brick wall cutoff at 20Hz. Even so; its mic/RTA shows response dipping below 20Hz-- but that could be the room and the usual nearby 18-wheeler truck traffic, and jets flying over (my house is in the approach path for the Savannah airport).
The Ripole patent contends that it can play 10Hz below the woofers' f/s (31Hz in free air), which would be 21Hz in this case-- and I can certainly feel that when I play a tune with profoundly low bass content, like Bela Fleck's "Flight of the Cosmic Hippo".
A Ripole's output is dipolar (although the lobes are more cordoid than figure-eight), so its off-axis output is effectively nulled, and its energy confined within the lobes, and stronger in the near field, as the dipole phase cancellation would progressively reduce the low end in the far field. That being the case; room size and volume settings would be variables.
I cross the Ripoles in at a very low 65Hz using a 24db/octave filter slope, so as not to excite their chamber resonance, which occurs somewhere north of 200Hz. I don't need to play them higher in my setup because the 12" woofers in my hybrid ESL's are perfectly adequate above 65Hz.
At the frequency I have the Ripoles crossing in; they are completely un-localizable, and I seldom even notice they are playing. But if I shut off their amp; their absence becomes immediately apparent, as the foundation of the music disappears.
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November 28, 2021, 11:41 AM #6
- Join Date
- Nov 2021
- Location
- Savannah, GA
- Posts
- 33
Re: Ripole Subs
Was still at it-- I think I've had enough of speaker building (too much work for an old guy), and this may be my last project.
About measurements; sorry I have none. Maybe I should get with the times and learn how to use REW?
I actually downloaded the REW program but I couldn't figure out how to feed in the test tones without adding a preamp and using a really convoluted path which would be different than the signal path I use for music.
Specifically; I don't use an analog preamp in my system and I don't have compatible inputs for the test tones, as I stream from a Logitech Transporter directly into a DSP crossover, using the Transporter's internal digital preamp.
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November 28, 2021, 11:51 AM #7
- Join Date
- Nov 2021
- Location
- Savannah, GA
- Posts
- 33
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AudioShark forum is a leading forum site for High End Audio Discussion, Stereo System Discussion, Home Theater System Discussion, Best Home Stereo System Discussion, Home Theater Installation Discussion etc.
The AudioShark forum was created for sharing the passion of high-end Audio. We have Audiophiles from all over the world participating and sharing their knowledge. From novice to experts, you will find a friendly environment for discussing about High End Audio, Stereo System, Home Theater System, Home Stereo System, Home Theater Installation, Amplifiers, Speakers, Subwoofers, Integrated System, Acoustic treatments & Digital Room Corrections and many more.
At AudioShark, we also have incorporated an exciting Marketplace where members can peruse terrific buys on used gear, as well as meet dealers and discuss the purchase of new gear.
We are as crazy about this hobby as you are! So come on in and join us! Audioshark.org the Friendliest Audio Forum!
Industry Participation Disclosure : The owner and administrator of Audioshark is the owner of Suncoast Audio LLC in Sarasota Florida. Suncoast Audio has a full brick and mortar presence in Sarasota with several great show rooms with many world class brands. More information can be found at http://www.suncoastaudio.com
Audioshark is a community of like minded individuals. Audioshark welcomes participation from all manufacturers and owners of all brands and products. It is our belief that online forums provide a community of like minded audiophiles and music lovers to encourage the growth of this wonderful hobby.
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I or anyone interested should see if FEDEX offers a domestic "LAST MINUTE RATE" for shipping heavy items within CONUS. Have no clue at this point - but when I have some time, I'll check. ...
Shipping Overseas 498 pounds w/3...