Advantages of Series Crossover vs Parallel for Subs & Open Baffle

@perrymarshall
The only clean, simple and straightforward way I know of to make reflected energy match direct energy is with a dipole woofer and CD tweeters pointing both directions. Possible, even elegant with a 2-way.

Have you tried modify compression driver and install waveguide both sides of membrane?

Other question:
Today's rooms are very undapmed - lack of carpet, furnitures, large windows. People buy speakers for the look like B&W 603 S3. What to do? Install traps or better reflectors or both? I'm thinking about 3D printed Helmholtz arrays.
 
@tubelectron Let me ask my question again, in a different way.
When does a system transition from "dipole" to "ripole"??????

Dave.

Ah, OK - my apologies, @Davey : I'm not english native language... :rolleyes:;)

Yes, the Ripole is a variant of the Dipole, in the sense of the back radiation pattern is different from the front radiation pattern, more cardioïd as stated by @Kjeldsen, and this change is re-used to increase the low extension.

I let Mr Ridtahler explain it himself, from an interview published on https://www.lautsprechershop.de/hifi/ridtahler_en.htm :

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Below, a document showing the transition from Dipole to Ripole, through several known variants ...

1703681910614.png


Below, a document from Axel Ridtahler comparing - from Left to Right - the respective differences in bass response and polar radiation between :
  • a sealed enclosure of 340L,
  • a plane open baffle of 1m2,
  • a BMC-type Ripole (= 2 drivers face-to-face), with the effect of an added lowpass filter (in blue),
All three used the same model of 15" woofers.

1703678544126.png


T
 
@tubelectron Yeah, I've read all of that many years ago, thank you.
It's not clear to me what innovation was accomplished here since the more complicated Linkwitz models are essentially the same thing and pre-date anything Axel implemented. (By at least ten years.)
The Ripole is clearly not a cardioid in any implementation, and much more closer to dipole in all the variants I've seen.

Your photo examples above are dipoles not "ripoles." :)

Dave.
 
@tubelectron Yeah, I've read all of that many years ago, thank you.
It's not clear to me what innovation was accomplished here since the more complicated Linkwitz models are essentially the same thing and pre-date anything Axel implemented. (By at least ten years.)
The Ripole is clearly not a cardioid in any implementation, and much more closer to dipole in all the variants I've seen.

Your photo examples above are dipoles not "ripoles." :)

Dave.

Mr Ridtahler invented the Ripole principle and obtained a patent for it - filed in 1998 and granted in 2000 :

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What else ?

T
 
A WONDERFUL EXAMPLE >
Just look at the inductor count !
PS.
There are implications for phase response.

Yes. All speakers are perfectly in phase here : electric (same polarities, important on transients) and acoustic (no delay, important on post-transient, decay tones). Reversing any of those speakers destroys the phase and the tonal balance : we made the test to check that it is immediately audible.

This is a very simple solution, requiring few parts. It certainly not work in all cases, of course, otherwise it would have been used more often, you guess it !

Nonetheless, if the speakers can match well enough together (= no notable accidents in their response around FC), this is worth to test it, IMHO. The results may be surprisingly good and difficult to rival with more conventional crossover designs : that's what we observed here, at least by listening.

T
 
@tubelectron Yeah, ignoring is the way to do it. :)

You might want to take a look back to 1992 at Linkwitz' AES paper on a "Compact Dipole Loudspeaker."
This was the inspiration for the Audio Artistry commercial designs that came later.
The woofer system was a complicated baffle design (that's now come to be called the "W"-frame configuration) that is the same thing as what we seem to be calling "ripole" nowadays. :)
And, SL being the classy guy he was, wouldn't even take credit for it then. He was inspired by a similar DIY design he'd seen from a friend and built on it.

This is hardly a new configuration. In fact, I saw something not unlike this back in the late 70's here in Seattle at SpeakerLab.

I'm sorry, but I just don't have much respect for a hack who attaches a "ri-" on the front of somebody else's work and takes credit for it.

Dave.
 

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Ah, OK - my apologies, @Davey : I'm not english native language... :rolleyes:;)

Yes, the Ripole is a variant of the Dipole, in the sense of the back radiation pattern is different from the front radiation pattern, more cardioïd as stated by @Kjeldsen, and this change is re-used to increase the low extension.

I let Mr Ridtahler explain it himself, from an interview published on https://www.lautsprechershop.de/hifi/ridtahler_en.htm :

View attachment 1251730

View attachment 1251729

Below, a document showing the transition from Dipole to Ripole, through several known variants ...

View attachment 1251737

Below, a document from Axel Ridtahler comparing - from Left to Right - the respective differences in bass response and polar radiation between :
  • a sealed enclosure of 340L,
  • a plane open baffle of 1m2,
  • a BMC-type Ripole (= 2 drivers face-to-face), with the effect of an added lowpass filter (in blue),
All three used the same model of 15" woofers.

View attachment 1251715

T
It does not make much sense to compare the same woofer I different setups. A woofer for a plane open baffle can work very well with parameters, that will look quite bad in a closed box. It could be fun to compare a high quality woofer with Qts above 1 in the same way
 
Very interesting discussion. If one designed a two way 1st order series crossover for woofer and wide band (FR) could one add a helper tweeter/super tweeter by simply paralleling a cap blocked tweeter or would a redesign as a three way be necessary?

Yes, it is certainly doable, the additional tweeter would then be paralleled with the rest of the crossover, but would not benefit of the advantages of the serial configuration. If it was me, I would redesign the whole in a complete 3-way serial mode, like I did for my 375L loudspeakers.

T
 
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@perrymarshall


Have you tried modify compression driver and install waveguide both sides of membrane?

Other question:
Today's rooms are very undapmed - lack of carpet, furnitures, large windows. People buy speakers for the look like B&W 603 S3. What to do? Install traps or better reflectors or both? I'm thinking about 3D printed Helmholtz arrays.
I've thought about a two-sided waveguide on a compression driver, never got further than that.

I think some of us unconsciously furnish a room based on how echoey it is. You can always put up some bookshelves!
 
1 - the speakers are connected in same polarity. This means that on a transient wave, the cones will move in the same direction, without any other delay than the construction flaws of each speaker can provide, unlike on most higher order crossovers.
In the real world, such series crossovers require inverting the polarity of one of the speakers to achieve correct phase alignment. With a 2 way crossover, the polarity of the tweeter is usually inverted, and with a 3 way crossover, the polarity of the midrange speaker is inverted.
 
@tubelectron Yeah, ignoring is the way to do it. :)

You might want to take a look back to 1992 at Linkwitz' AES paper on a "Compact Dipole Loudspeaker."
This was the inspiration for the Audio Artistry commercial designs that came later.
The woofer system was a complicated baffle design (that's now come to be called the "W"-frame configuration) that is the same thing as what we seem to be calling "ripole" nowadays. :)
And, SL being the classy guy he was, wouldn't even take credit for it then. He was inspired by a similar DIY design he'd seen from a friend and built on it.

This is hardly a new configuration. In fact, I saw something not unlike this back in the late 70's here in Seattle at SpeakerLab.

I'm sorry, but I just don't have much respect for a hack who attaches a "ri-" on the front of somebody else's work and takes credit for it.

Dave.

celestion system 6000 1987 , maybe ?

 
In the real world, such series crossovers require inverting the polarity of one of the speakers to achieve correct phase alignment. With a 2 way crossover, the polarity of the tweeter is usually inverted, and with a 3 way crossover, the polarity of the midrange speaker is inverted.

Unfortunately, in the real world, that doesn't work like this in a 1st order serie crossover, being in 2 or 3 ways, or over : any polarity inversion is heard as a scooped mid tone, and the transient response is erased. You guess that I made the test several times on several enclosure projects, and each time : same conclusion...

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T
 
Unfortunately, in the real world, that doesn't work like this in a 1st order serie crossover, being in 2 or 3 ways, or over : any polarity inversion is heard as a scooped mid tone, and the transient response is erased. You guess that I made the test several times on several enclosure projects, and each time : same conclusion...
Can you confirm this with real measurements of your designs?

Besides, the crossover of these small monitors has no baffle step compensation, it is too simple to talk about correct filtering of the speakers.
Those schematics you showed are book examples of theoretical filters that were not built based on real and correct acoustic measurements.
 
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