Ripol cavity resonance vs cross over design

[Heinrich]

have tried closed box, with small woofers (both standard and isobaric). It was not a success.

Thanks for the word of caution. Dipoles have their fans.

 

[Davey]

To run a woofer below its resonance goes back the early 70ies, when the Linkswitz transform / biquad wasn't yet available (in Germany). The design allows to compensate bass by a simple 2nd order lowpass, that 12dB/oct tilt. It is passed by Linkwitz, it is utterly obsolete since the advent of digital equalization. No use, never there was.

No, it goes back long before that.
And, the Linkwitz Transform does not define a particular implementation. The solution can be either analog or digital. This form of equalization is still perfectly valid today.

However, there is no free lunch. When used to compensate woofers installed in smallish sealed boxes, the power requirement increases greatly.

 

[Heinrich]

No, it goes back long before that.

Running a woofer below its resonance, really? I remember an article which in that very context describes the use of a specific gas (nitrogen, something else) that would virtually increase the volume by its special thermodynamic properties. As I said, very dark, desperate ages. Now people think more, but seems like the 'old wisdom' is still around for the worse.

 

[Davey]

Running a woofer below its resonance, really? I remember an article which in that very context describes the use of a specific gas (nitrogen, something else) that would virtually increase the volume by its special thermodynamic properties. As I said, very dark, desperate ages. Now people think more, but seems like the 'old wisdom' is still around for the worse.

You're not aware of speaker systems that operate their woofers below resonance?
Maybe the new ages of thinking need some adjustment?

 

[Heinrich]

You're not aware of speaker systems that operate their woofers below resonance?
Maybe the new ages of thinking need some adjustment?

Just tried to give some context to my response, as we clearly departed from the original topic's back and forth. Thing is, the woofer's resonance is of minor interest, if power and equalization take over. So, on topic, just some speaker in a box is a viable alternative to dipole, ripole, any pole, no pole and what else of esoteric rendition of incomprehensable theorizing. The "urps", as is cristianed in the link above, is special in that it has no meaning for itself. It was a worse German thing of me-know-better, and was debunked too late but entirely. But remember the finishing scene of "Time Bandits"? Some is always left ... you can't do anything about it.

There's a reason why an enclosure of some sort is the standard today.

[sarcasm] Better not. [/sarcasm]

 

[BrianKjeldsen]

@Heinrich sorry but I dont think you were ever on topic.

 

[BrianKjeldsen]

I was reading about Ripol subwoofers for years and I am intrigued as any subwoofer I tried (mostly closed box design) are sounding bloated compared to my bending wave drivers. These are almost full range from around 150Hz to 30kHz. I am not aiming with that sub for very low frequencies, -6dB at 30HZ would be more than acceptable.

There a very few commercial subwoofers based on Ripol design like Voxativ, Modal and just announced Borrensen bass modules(no data yet). So likely I will be more interested in building my own ones.

Most Ripol designs are based on 12" drivers and have the cavity resonances often around 300Hz or a little lower. Would a design with smaller woofers and therefore smaller cavities significantly increase the cavity resonance frequency?

A crossover frequency of 150Hz would require a step slope but even that may be not quite enough. A notch filter would be useful but I am interested in using active crossovers and built in notch filters are not common. Presently I am using a Devialet amp with its built in digital crossover which allows 4th order slopes (my measurements show effectively more a third order slope). I am contemplating the use of an active analog crossover as digital ones induce a time delay of at least 20ms. I have not seen any ones with notch filters except the one from Alex Ridthaler (the inventor of the design) which are not anymore available.

Yes, you can use multiple 6-8 inch woofers and cavity resonance will increase significantly. I know of a DIY design doing this, and it have even impressed a genuin well regarded audio engineer, who works with loudspeaker driver development for some very known brands.

 

[Heinrich]

@Heinrich sorry but I dont think you were ever on topic.

See post #3, and so I think my sarcasm towards tinkerers would have been perfectly appropriate. And it was you to put it deliberately off tracks, and saying so in posts #36/38. There you are.

 

[BrianKjeldsen]

And I am sorry I did that. I should have send you a private message.