Ripole with 15" woofers

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I got a quartet of GOLDWOOD SOUND GW-215/40/8 woofers, and would like to build a pair of Ripole subs.

What is the highest frequency I could reach depending on the size of the front slot and of the rear openings? Could I reach 200 hz, possibly with a bit of EQ (I have a pair of Hypex Fusion FA501 amps)?
 
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I have researched the Ripole Model, I can't offer much to help with the EE Math, as this is not my skill set, and I would get help with this.

I can offer advice on the Housing and have attached a information I downloaded of a Housing Drawing Plan,
for Dimensions of a Double Ripole using 15" Bass Drivers.

Ripole Cabinet Drawing for a 15 inch Bass Driver - Amended Dimension.png
 
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You sure can. Check out visaton petit orgue, or grand orgue.

Hi,
I went to your Blog, interesting projects you made for yourself.
I am interested in the TB W5-15611 SAf with the mounted tweeter, questions, please

what is the x-over freq. you are using?
any tweeter you think I should not try, does most tweeters in this config work?

Thanks
BTW thks for info on visaton petit orgue, or grand orgue
 
music soothes the savage beast
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hi ttan98, i hope mocenigo does not mind if i reply here
crossover:
there is no crossover on fullrange, just one cap on the tweeter
i use 4.7uF on the tweeter, which is specified 6ohm, so crossover point would be ~6kHz
the point here is to maintain uniform off axis response, to make direct and reflected sound similar
without tweeter, it does not sound natural to me, with tweeter, its fun to listen to
I use sub below ~150Hz

when it comes to tweeter, the smaller the better
i have good luck with small dayton domes, they are cheap but perform very well
https://www.parts-express.com/Dayto...oft-Dome-Neodymium-Tweeter-275-025?quantity=1
Dayton Audio ND20FB-4 Rear-Mount 3/4" Soft Dome Neodymium Tweeter
 
I got a quartet of GOLDWOOD SOUND GW-215/40/8 woofers, and would like to build a pair or ripple subs.

What is the highest frequency I could reach depending on the size of the front slot and of the rear openings? Could I reach 200 hz, possibly with a bit of EQ (I have a pair of Hypex Fusion FA501 amps).

A Ripole with a 15" driver will have a resonance at around 150Hz-200Hz. The resonance will be sharp/peaky because the cavity of the Ripole is deeper than it is wide. This makes the Q of the resonance high, and you must make sure to EQ this down properly. I would not recommend trying to use the Ripole above about 0.75 times the frequency of the resonance. This limits it to no higher than 125-150 Hz.
 
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A Ripole with a 15" driver will have a resonance at around 150Hz-200Hz. The resonance will be sharp/peaky because the cavity of the Ripole is deeper than it is wide. This makes the Q of the resonance high, and you must make sure to EQ this down properly. I would not recommend trying to use the Ripole above about 0.75 times the frequency of the resonance. This limits it to no higher than 125-150 Hz.

Thank you. Indeed I figured out that the chamber resonance is mostly due to the front chamber (the one for the rear chambers will be either equal or higher, often significantly so, depending on the actual geometry) so it should be speed_of_sound/(2 Pi) * sqrt(area of mouth / (volume * depth)) and for a, say, .4*.4 m cavity 10cm wide we would have 136 Hz. So 100 Hz would be the topmost useable frequency. I'll try to aim for 80 or 90.

Roberto
 
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closed account
Joined 2007
hi ttan98, i hope mocenigo does not mind if i reply here
crossover:
there is no crossover on fullrange, just one cap on the tweeter
i use 4.7uF on the tweeter, which is specified 6ohm, so crossover point would be ~6kHz
the point here is to maintain uniform off axis response, to make direct and reflected sound similar
without tweeter, it does not sound natural to me, with tweeter, its fun to listen to
I use sub below ~150Hz

I use a similar trick with a super tweeter next to a Le'cleach horn loaded compression coax.
 
hi ttan98, i hope mocenigo does not mind if i reply here
crossover:
there is no crossover on fullrange, just one cap on the tweeter
i use 4.7uF on the tweeter, which is specified 6ohm, so crossover point would be ~6kHz
the point here is to maintain uniform off axis response, to make direct and reflected sound similar
without tweeter, it does not sound natural to me, with tweeter, its fun to listen to
I use sub below ~150Hz

when it comes to tweeter, the smaller the better
i have good luck with small dayton domes, they are cheap but perform very well
Dayton Audio ND16FA-6 5/8" Soft Dome Neodymium Tweeter
Dayton Audio ND20FB-4 Rear-Mount 3/4" Soft Dome Neodymium Tweeter[/QUOTE
Many thanks
 
Hmm, haven't followed any of the ripole threads, just read this and did a quickie sim 'blending' in what I [think I] know about BP6 design and came up with 400+Hz, 1200+Hz peaks, so please review and tell me where I went wrong.

TIA

From the page you linked above:
Expect a chamber resonance of up to 20db to develop between 200hz-300hz
That figure of 200-300Hz is for the Ripole design using a 12" driver. In that case the depth of the cavity is a little over 12", enough to accommodate the frame plus an inch or two, e.g. 13"-14".

The resonance is a 1/4 wave resonance of the "slot" or "tunnel". The depth of the tunnel is what determines its resonance frequency. Of course a 15" driver requires a deeper tunnel to physically fit inside, so the resonance frequency will be lower than the 200Hz mentioned in the article. Around 150Hz is about right. It could be slightly higher.

I have no idea how you calculated your numbers, but figuring out the resonance frequency is relatively easy. It's
0.25*c/d
where c=345m/s (the speed of sound) and d is the depth in meters. One meter is about 40 inches.

For a depth of 14" this comes out to 245Hz
For a depth of 17" this comes out to 202Hz

That's the frequency of the peak, and I find it can be a little optimistic (it's often slightly lower, maybe the air adjacent to the opening is part of it, like what happens with a flush port). The response will be sharply rising up to the peak for a Ripole and it is hard to EQ properly, so you just cross over low enough to suppress the peak.

Here is the frequency response of the Ripole sub by this company that uses a 12" driver, including crossover. That little blip at 200Hz is what remains of the peak of the tunnel resonance after the response is rolled off much lower:
ripol30_freq.gif
 
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I know the petit orgue (having heard it) and also know the design of its big brother. But it uses 10” woofers. I am interested in computing the resonance of a generic Ripole given its various parameters. Because I have 15” woofers.

Roberto
If you can send cabinet CAD drawing in format to what can be added interfaces with Fusion360 and element T/S parameters, I can make Akabak simulation.
Ripole is very special case and I am not 100% sure simulation will be precise enough but it is interesting to test Akabak with it.
 
The resonance is a 1/4 wave resonance of the "slot" or "tunnel".

Thanks! Yes, know all that as I damped it out in the design to get a wider BW since I didn't find any measurements to compare to, so was more interested in where I went wrong in the sim.

Looking at it with 'fresh eyes' though, the parallel BP6 wizard won't work because I can't time shift the driver chamber 'vent' ~180 deg, making the summation all wrong, so will try with the 'H' frame dipole.
 
music soothes the savage beast
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A Ripole with a 15" driver will have a resonance at around 150Hz-200Hz. The resonance will be sharp/peaky because the cavity of the Ripole is deeper than it is wide. This makes the Q of the resonance high, and you must make sure to EQ this down properly. I would not recommend trying to use the Ripole above about 0.75 times the frequency of the resonance. This limits it to no higher than 125-150 Hz.

CharlieLaub, that sounds logical.
What if ripole is constructed instead of parallel walls, in shape of Z. Driver in the middle, two wing like panels on each side pointing oposite each other. You get an idea, like Z.
This way gap does not have parallel walls, so resonance should be low Q.
 
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What if ripole is constructed instead of parallel walls, in shape of Z. Driver in the middle, two wing like panels on each side pointing oposite each other. You get an idea, like Z.
This way gap does not have parallel walls, so resonance should be low Q.

In that case it is no longer a ripole. The ripole is characterised by the fact that it has at least one tight compression chamber. Related to it is Pass’s slot loaded open baffle.

What you are proposing is a quite common space saving open baffle, namely the “N” shape, which, rotationally, is a “Z”.
 
closed account
Joined 2007
If you can send cabinet CAD drawing in format to what can be added interfaces with Fusion360 and element T/S parameters, I can make Akabak simulation.
Ripole is very special case and I am not 100% sure simulation will be precise enough but it is interesting to test Akabak with it.

Kaameelis, would normal paper drawings (scanned) be ok or you actually input the CAD drawing to akabak?
 
music soothes the savage beast
Joined 2004
Paid Member
In that case it is no longer a ripole. The ripole is characterised by the fact that it has at least one tight compression chamber. Related to it is Pass’s slot loaded open baffle.

What you are proposing is a quite common space saving open baffle, namely the “N” shape, which, rotationally, is a “Z”.

oh crap, i though i finally invented something :) never mind, i will call my Z shape open baffle 'crapole'
 
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