The Modal Akustik subs are stacked layers of alternating clear and colored (black or white) polycarbonate plastic. Mine are red oak.
Yet another Ripole sub project
- Thread starter Jazzman53
- Start date
Help Support MartinLogan Audio Owners Forum:
The Modal Akustik subs are stacked layers of alternating clear and colored (black or white) polycarbonate plastic. Mine are red oak.
- Joined
- Mar 17, 2022
- Messages
- 499
- Reaction score
- 392
I would 100% buy those if you were local. Beautiful workmanship
I've received requests for an easier-to-build version of my Ripole sub so I've drawn one up that omits the rounded edge members; living the plywood edges exposed. Below is a screenshot of the drawing. If anyone wants the CAD drawing just PM me an email address.
I assume you were referring to the Modal Akustik subs, which are indeed made of stacked layers of polycarbonate plastic. Polycarbonate is a very strong/rigid plastic so I doubt it adds any objectionable sonics.
Great job Charlie. Always enjoy other peoples projects.
Liquisonic
Member
Hey Jazzman, long time no read 
... 
I always wondered how your Ripole subs operated in practice, interesting read on the dispersion pattern.
A classic figure of 8, with an 'anti-matter half-wave' that faces the wall, and/or, away from the listener is how I understood it?
That's a head-scratcher to me, but I trust your impressions when you say they sound excellent.
Some time ago, I was offered a pair of HT-18's, and a pair of their big brothers, the DS-4 18's from Sundown.
They were such a good deal I couldn't pass them up, but what to do with these monsters?
So I built a manifold and opened up the (main) floor above them for a basement IB sub that was up & out of the way.
Well, sure enough the IB mantra "hear the bass, not the box" was true, but slower than a Paddlewheel on Molasses River..
-
*ehem* ...at least to my way of judging their 'rhythm & pace' characteristics (a term I once believed pure Stereophile B.S.)
So, the Infinite Baffle is coming down, & the ceiling hole is going to be sealing shut for (lack of) good.
I'm just wondering if those beasts of sonic boom would work well in Ripole configuration.
Any thoughts?
-Steve
BTW, My main T-lines (ESL lows) employ (pre SLS) Peerless CSX10s , the closest TS match i could source to the famous B-139 of IMF fame.
... I always wondered how your Ripole subs operated in practice, interesting read on the dispersion pattern.
A classic figure of 8, with an 'anti-matter half-wave' that faces the wall, and/or, away from the listener is how I understood it?
That's a head-scratcher to me, but I trust your impressions when you say they sound excellent.
Some time ago, I was offered a pair of HT-18's, and a pair of their big brothers, the DS-4 18's from Sundown.
They were such a good deal I couldn't pass them up, but what to do with these monsters?
So I built a manifold and opened up the (main) floor above them for a basement IB sub that was up & out of the way.
Well, sure enough the IB mantra "hear the bass, not the box" was true, but slower than a Paddlewheel on Molasses River..
- *ehem* ...at least to my way of judging their 'rhythm & pace' characteristics (a term I once believed pure Stereophile B.S.)So, the Infinite Baffle is coming down, & the ceiling hole is going to be sealing shut for (lack of) good.
I'm just wondering if those beasts of sonic boom would work well in Ripole configuration.
Any thoughts?
-Steve
BTW, My main T-lines (ESL lows) employ (pre SLS) Peerless CSX10s , the closest TS match i could source to the famous B-139 of IMF fame.
Attachments
Hi Steve,
The real RiPol gurus are on the DIY Audio Forum, subwoofer section. I would go there and query posts by "Rudolf" and "Calvin", and post your questions in that forum.
But since you've asked, I will give you my gut feel on those Sundown woofers: They're too big Let me explain:
I prefer woofers no larger than 12" in a RiPol because a larger woofer needs a larger baffle, which increases the chamber length, which lowers the frequency of the [loud/undesirable] chamber resonance. And this ultimately limits the usable bandwidth.
A 12" woofer in an minimal chamber would have a resonance peak somewhere around 250Hz, and you would need to crossover about an octave below the chamber resonance to avoid exciting it. You can see where this is going if the chamber has to be much bigger (and resonate much lower) to use an 18" woofer...
It's counter-productive to make the chamber depth larger than necessary to accommodate the woofer. And even if using 12" wooers, I would cross them in <100Hz using a steep filter slope to avoid exciting the chamber resonance.
Additionally, I would avoid woofers with Qts <0.4 because too much EQ would be needed to flatten the low-end roll off. I like the Qts to be around 0.5, which doesn't need a lot of EQ'ing, yet still gives tight bass (high-Qts / floppy woofers sound muddy to me).
Of course; plenty of X-max is mandatory because there is no box-trapped air mass limiting the cone excursion.
Low-moving mass and low inductance give the best transient response (speed), but low-inductance (low back-EMF) trumps moving mass, if you can't have both.
That's my take on woofer parameters.
The real RiPol gurus are on the DIY Audio Forum, subwoofer section. I would go there and query posts by "Rudolf" and "Calvin", and post your questions in that forum.
But since you've asked, I will give you my gut feel on those Sundown woofers: They're too big
Let me explain: I prefer woofers no larger than 12" in a RiPol because a larger woofer needs a larger baffle, which increases the chamber length, which lowers the frequency of the [loud/undesirable] chamber resonance. And this ultimately limits the usable bandwidth.
A 12" woofer in an minimal chamber would have a resonance peak somewhere around 250Hz, and you would need to crossover about an octave below the chamber resonance to avoid exciting it. You can see where this is going if the chamber has to be much bigger (and resonate much lower) to use an 18" woofer...
It's counter-productive to make the chamber depth larger than necessary to accommodate the woofer. And even if using 12" wooers, I would cross them in <100Hz using a steep filter slope to avoid exciting the chamber resonance.
Additionally, I would avoid woofers with Qts <0.4 because too much EQ would be needed to flatten the low-end roll off. I like the Qts to be around 0.5, which doesn't need a lot of EQ'ing, yet still gives tight bass (high-Qts / floppy woofers sound muddy to me).
Of course; plenty of X-max is mandatory because there is no box-trapped air mass limiting the cone excursion.
Low-moving mass and low inductance give the best transient response (speed), but low-inductance (low back-EMF) trumps moving mass, if you can't have both.
That's my take on woofer parameters.
Last edited:
Similar threads
- Locked
