Considering ripole, but are these drivers suitable?

[kenpeter]

Nobody forces you to use that design.

Wrong. Entirely wrong! And against my protest every time...
I was recently threatened in this very thread with a batch
of failed ripoles, "Weather I like it or not."

vs. other people around here who are just ridiculing it
probably without ever having heard one.

I've heard (and soldered and measured) Zob's ripole disasters
way too many times for it to even be funny anymore. No wait,
yup, its still funny...

 

[Kjeldsen]

I once heard a 2 way chinese OB with one meter ribbon. It sounded awfull. But that does not mean that OB sound awfull.

 

[hurz]

Played with moving the ripole away from the rear wall towards the mic.

• As the ripole is moved away from the rear wall towards the mic, the SPL goes up. This could be due to a combination of enhanced dipole sub action (rear wave delay) and also physically reducing the distance between the device close to the mic in a rather small room
• Pointing the slot directly at the mic removed a rather large null around 90 Hz . This was interesting to note (compare curves 2 and 3, for example).

See, that's what I meant, the position and especially the tow-in have a huge effect on which room modes are amplified. The distance is of course crucial, due to the stronger attenuation by the reflected rear waves. Unlike monopoles, where all the room's dimensions are affected, the typical figure-8 dispersion of dipoles will only influence some modes while others are hardly affected. It will also generate a directivity. If you stand right beside the dipole the bass will be significantly less than facing the mouths, so the listening spot should definitely be overlapped by the figure-8 of both ripoles.
As you can also see in the measurements of my ripoles, I hugely improved my nasty room mode around 23Hz just by using a ripole instead of the old subwoofer. At those frequencies there is not a lot one can do with absorbers and the like.
I would tow in both ripoles to your listening spot and move them away from each wall as far as possible, at least a meter or so. Pretty much all speakers that don't need a corner position for additional bass will benefit from being placed away from walls, so the ripoles can easily be used as stands for the Front speakers, if space and esthetics allow.

@kenpeter: Just because you heard a lot of ripole "disasters" doesn't mean the concept doesn't work if done right, as kjeldsen pointed out. I heard a lot of monopole disasters (especially subwoofers) but wouldn't dream of riducling this whole principle just based on some observations. People like Linkwitz (and many others) use/plan/construct dipoles very effectively on a daily basis.
A ripole is not very different from those concepts and its obvious benefits are well understood and easily proven, even if not your cup of tea. If max SPL is what you're after I would neither use dipoles nor traditional subs but rather some horn concepts or the like, to achieve some 130dB in-room, for whatever reason I would need that other than bragging about it.

 

[hurz]

Once more the reminder:
As I mentioned before, the nasty, high resonances above 200Hz are inherent to this design. The smaller the ripole, the higher their frequency, but you still have to correct them. Best cut them off completely via a multi-order low pass or crossover.
I'd suggest a maximum cut-off around 120Hz, if possible lower.
Otherwise the ripole will obviously sound crappy with any real music/movies and never work correctly.
I suspect those resonances are one of the main factors your overall volume is very low. Avoiding those and the unneccessarily high excursion in that area of frequencies might also enable you to go louder at the lower frequencies. That was also a crucial point in some ripole projects around the German forums.

For example: your peak around 240Hz is about 18dB(!) louder than your 120Hz volume. That's a factor of 8 while the excursion needed at 120Hz is roughly only twice the one at 240Hz.
So I really think that the resonances are limiting your max excursion at the usable frequencies below and you could significantly increase the volume output if those resonances are dealt with.
BTW, I just stumbled upon a very nice DIY speaker build with included dual-ripole: DIY speaker with Manger and dual ripoles

 

[Kjeldsen]

Played with moving the ripole away from the rear wall towards the mic.

• As the ripole is moved away from the rear wall towards the mic, the SPL goes up. This could be due to a combination of enhanced dipole sub action (rear wave delay) and also physically reducing the distance between the device close to the mic in a rather small room
• Pointing the slot directly at the mic removed a rather large null around 90 Hz . This was interesting to note (compare curves 2 and 3, for example).

You need to get rid of that peak above 180 Hz. Every OB design from flat baffle, U baffle and ripole have this peak more or less. It's got to go away completely.

 

[tb46]

Hi zobsky,

You are providing some very interesting data. I'm looking forward to read your results on the sonotube experiment.

Regards,


Hi hurz,

Have you tried absorptive panels behind the ripol, and do you think that would help?

Post #104: "... the nasty, high resonances above 200Hz are inherent to this design. The smaller the ripole, the higher their frequency, but you still have to correct them."

Is the result of using active electronic equalization the same as using a passive filter? Do you have experimented with both?

Regards,

 

[zobsky]

Hi zobsky,

You are providing some very interesting data. I'm looking forward to read your results on the sonotube experiment.

Regards,


Hi hurz,

Have you tried absorptive panels behind the ripol, and do you think that would help?

Post #104: "... the nasty, high resonances above 200Hz are inherent to this design. The smaller the ripole, the higher their frequency, but you still have to correct them."

Is the result of using active electronic equalization the same as using a passive filter? Do you have experimented with both?

Regards,

I tried the sonotube last evening . I used a piece of coarse jute to keep the filling from falling into the driver cavity (created by rotating the ripole center piece by 90 degrees )
Unstuffed, there was a huge 1/4 peak at about 80 Hz, as expected . Adding stuffing dampenes the peak somewhat, with more bass over the entire spectrum . However, even moderately stuffed, I really didn't get significantly more low bass compared to the ripole, perhaps not enough enclosure volume and / or line length to support low Hz .
Also, the bottoming out issue was reduced but not eliminated, mostly because of the increase in overall SPL.
Subjectively, the ripole is a bit cleaner, smaller, less efficient and bottoms out "a bit easier" than the TL version

 

[adason]

in ripole, those two woofers work against each other, slowing the cone movement of oposite woofer
how can you expect any decent bass
its just a bad concept

 

[zobsky]

in ripole, those two woofers work against each other, slowing the cone movement of oposite woofer
how can you expect any decent bass
its just a bad concept

Hi adason,
... but they're also firing in phase, pretty much like a linkwitz baffle (except that the drivers are set up with cone facing cone and with smaller cavities - as opposed to magnet facing cone, in a linkwitz baffle), See http://www.linkwitzlab.com/woofer.htm

I looked briefly at your dipole design. The woofers are acoustically out of phase. How does it work? (unless I grossly misunderstand).

Thanks

 

[kenpeter]

Suspension of disbelief - Wikipedia, the free encyclopedia

 

[hurz]

Have you tried absorptive panels behind the ripol, and do you think that would help?

Hi tb46,
absorbative panels won't help behind the ripole as at those frequencies (say 20 to 100 Hz) they'd have to be very very thick (at least a quarter of the wavelength) which isn't practical for low bass.
There are bass absorbers for the corners which help a little or one could use helmholtz resonators as bass traps (that would probably be the most promising without imposing too much) but as my listening room is my living room it would neither be practical nor would my wife allow me to do that
In a dedicated man-cave I'd think about that of course.

Is the result of using active electronic equalization the same as using a passive filter? Do you have experimented with both?

I currently use both. A passive notch filter deals with the resonances themselves (I got it from Axel Ridthaler, the ripole's inventor, but it's easy enough to DIY). That's definitely preferable to a regular low-pass as it's not easy to build the latter steep enough.
Additionally I have a crossover in the miniDSP in place at my desired frequency.
Using just an active filter is also possible, but it should be a very steep low pass or also a notch filter combined with a crossover. If you look at zobsky's measurements and the huge peak the resonances create, a 12dB or even 24dB crossover by itself will not be enough as you'd still hear the resonances overlaying your mains.
The best solution imho is a (passive or active) notch filter to deal with the resonances (makes senso to come with the ripole itself as a unit) and a variable, regular crossover (doesn't have to be very steep) to cross to the mains. The latter can by any DSP, AVR, or the like.
If you're only crossing once actively or via DSP without further corrections, I'd suggest something like an eight-order (or steeper) filter (Linkwitz-Riley-8 or double butterworth), which is something that is not as easy to build passively and will introduce a lot of phase shift.

For the ripole to work correctly one HAS to get rid of those resonances one way or the other.

 

[tb46]

Hi hurz,

Thanks for the additional information.

Regards,

 

[zobsky]

Hi tb46,
absorbative panels won't help behind the ripole as at those frequencies (say 20 to 100 Hz) they'd have to be very very thick (at least a quarter of the wavelength) which isn't practical for low bass.
There are bass absorbers for the corners which help a little or one could use helmholtz resonators as bass traps (that would probably be the most promising without imposing too much) but as my listening room is my living room it would neither be practical nor would my wife allow me to do that
In a dedicated man-cave I'd think about that of course.


I currently use both. A passive notch filter deals with the resonances themselves (I got it from Axel Ridthaler, the ripole's inventor, but it's easy enough to DIY). That's definitely preferable to a regular low-pass as it's not easy to build the latter steep enough.
Additionally I have a crossover in the miniDSP in place at my desired frequency.
Using just an active filter is also possible, but it should be a very steep low pass or also a notch filter combined with a crossover. If you look at zobsky's measurements and the huge peak the resonances create, a 12dB or even 24dB crossover by itself will not be enough as you'd still hear the resonances overlaying your mains.
The best solution imho is a (passive or active) notch filter to deal with the resonances (makes senso to come with the ripole itself as a unit) and a variable, regular crossover (doesn't have to be very steep) to cross to the mains. The latter can by any DSP, AVR, or the like.
If you're only crossing once actively or via DSP without further corrections, I'd suggest something like an eight-order (or steeper) filter (Linkwitz-Riley-8 or double butterworth), which is something that is not as easy to build passively and will introduce a lot of phase shift.

For the ripole to work correctly one HAS to get rid of those resonances one way or the other.

I'll play with the filters some more . Whatever the outcome, I at least get to to refresh my DIY and measurement skills after a 2 year injury-related go-slow/hiatus from the hobby. Warmup for other projects.

The german ripole you posted looks a lot like the winged SLOB that I built (that creation also had 4 drivers per channel) and is currently banished to a dark corner of the attic (it was way too big in pure slot loaded open baffle mode)

 

[zobsky]

Wrong. Entirely wrong! And against my protest every time...
I was recently threatened in this very thread with a batch
of failed ripoles, "Weather I like it or not."

And I stand by that threat. You'll have to bear being near them if we're going to work on the paraline project together.

At least I got the measurement rig all set up

 

[linaudio]

I suspect we've (unintentionally, in my case) scared off and / or confused the original poster away

Neither scared off nor confused, simply trying to find the time to finish the ripole. A little delayed due to a silly mistake when routing the holes for the driver magnets, but I'm hoping to have it sorted out and assembled sometime next week. Listening impressions and measurements to follow...

 

[kenpeter]

Listening impressions and measurements and Viking funeral to follow...
But will it float?

 

[zobsky]

Neither scared off nor confused, simply trying to find the time to finish the ripole. A little delayed due to a silly mistake when routing the holes for the driver magnets, but I'm hoping to have it sorted out and assembled sometime next week. Listening impressions and measurements to follow...

Great, good to hear that your curiosity has been piqued and sawdust has been produced despite (or because of) our rabid rants. Best of luck.

 

[rowuk]

I know that this is an "old" thread, but I read every post to get a feel for what is what. Having heard a good working Ripole, I wonder why the drama here. Those opposed to open back don't need to read the "nonsense" or even comment. One thing that we all experience however is that low bass in normal sized rooms presents BIG problems that we have no real solutions for. The resonant modes are there (in the box and in the room) and we feed them more with closed back technology than with open back. If we remember that a resonance in the room is NOT just the music louder at a particular frequency, rather a sympathetic note created by the room, we will realize that pressure response is not a sign of anything. Bottoming out of the drivers is simply stupid integration. With an open back, or ported speaker for that matter, we SHOULD limit LF to what the concept can handle. Those looking for HT slam, probably will be more happy with room resonances...

Maybe we need a discussion about what room gain is and does?