This is great and I will be watching with interest. I had hoped we would see more action on the Ripole subject as I have a salvaged Wurlitzer organ speaker that I would like to use as part of my keyboard amplification system.
Unfortunately due to the Fs of 45Hz, Low Qts of about .3 and very large Vas (about 12cu ft if I remember right) any conventional cabinet I have come up with is rather large for portable use. It models very well in a TL but would be huge.
I am hoping that the lowering of Fs would get me into the 30s and that the loading will up the q a bit so that it doesn't roll off so quickly. I will be pairing it with either a 12" organ speaker and Piezo horn or possibly a 10" dual cone organ speaker.
mike
Unfortunately due to the Fs of 45Hz, Low Qts of about .3 and very large Vas (about 12cu ft if I remember right) any conventional cabinet I have come up with is rather large for portable use. It models very well in a TL but would be huge.
I am hoping that the lowering of Fs would get me into the 30s and that the loading will up the q a bit so that it doesn't roll off so quickly. I will be pairing it with either a 12" organ speaker and Piezo horn or possibly a 10" dual cone organ speaker.
mike
Change of Track to Dipole
I made some comparisons to different rigged up dipole alignments (woofers on flat board vs woofers facing each other in 90 degree W dipole vs woofers facing each other in ripole).
Firstly, I think Calvin was right when he said that the PPA15 Qts is too high for ripole. I get the sense that the woofer motor doesn't have what it takes to drive the ripole.
Comparing the ripole to the woofers on a flat board, the ripole does go deeper but is somewhat less efficient (in the test, the ripole was unfortunately a bit closer to the mic so the SPLs appear almost even, .. sorry about that). The woofers on a flat board had more mid bass punch, which is something I referred to in my earlier posts. See my UNCALIBRATED SPL curves for reference.
Rigging up a crude W-baffle, this gave me the best results, ... solid bass punch + extension. I decided to persist with the 90 degree "V" with both woofers firing forward for reasons of symmetry and to have both drivers fire at the listener. At the same time, I don't have the real estate to devote to a full U-baffle, hence the compromise.
I have one or two other drivers that I think will work in a ripole, .. my trusty adire shiva 12 and a big dog university C-15W woofer. A project for another time. The pyles however seem to perform best in more conventional baffles.
Construction in progress.
Excuse the mess.
I made some comparisons to different rigged up dipole alignments (woofers on flat board vs woofers facing each other in 90 degree W dipole vs woofers facing each other in ripole).
Firstly, I think Calvin was right when he said that the PPA15 Qts is too high for ripole. I get the sense that the woofer motor doesn't have what it takes to drive the ripole.
Comparing the ripole to the woofers on a flat board, the ripole does go deeper but is somewhat less efficient (in the test, the ripole was unfortunately a bit closer to the mic so the SPLs appear almost even, .. sorry about that). The woofers on a flat board had more mid bass punch, which is something I referred to in my earlier posts. See my UNCALIBRATED SPL curves for reference.
Rigging up a crude W-baffle, this gave me the best results, ... solid bass punch + extension. I decided to persist with the 90 degree "V" with both woofers firing forward for reasons of symmetry and to have both drivers fire at the listener. At the same time, I don't have the real estate to devote to a full U-baffle, hence the compromise.
I have one or two other drivers that I think will work in a ripole, .. my trusty adire shiva 12 and a big dog university C-15W woofer. A project for another time. The pyles however seem to perform best in more conventional baffles.
Construction in progress.
Excuse the mess.An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
@zobsky some questions:
Did you measure all three configurations at the same position in the room? What was the mic distance?
Did you compare the cone excursion at the same SPL level between the "ripole" and the other configurations? The "ripole" may have been less efficient due to mass loading, but should do the same SPL level with less cone movement. Since dipoles are almost always limited by xmax first and not by power, the "ripole" may have been the winner at max SPL without power considerations.
Rudolf
Did you measure all three configurations at the same position in the room? What was the mic distance?
Did you compare the cone excursion at the same SPL level between the "ripole" and the other configurations? The "ripole" may have been less efficient due to mass loading, but should do the same SPL level with less cone movement. Since dipoles are almost always limited by xmax first and not by power, the "ripole" may have been the winner at max SPL without power considerations.
Rudolf
Have you tried an Y-Dipole ? It's kind of an U-frame with inwards-shaped, narrower back cavity. I owe 2 of these with high Qt drivers (Eminence Alpha 15 A) and I am quite satisfied. IMHO, there are a few advantages over other topologies:
- lower extension and SPL, the driver "sees" a larger equivalent baffle
- "good" mass loading - one can search for a compromise in the back wings length w.r.t. quarter wave resonance, mass loading and SPL.
- lower space requirements (one has a front baffle with inward wings)
While there are reasons for not using inward "wings" in a fullrage OB, I see no problem with that for low frequency (mine are crossed over at 160Hz LR4). For music, I don't feel the need of more SPL or extension and the bass is powerful, clean and tight(yes, midbass also).
For HT...I wouldn't know, but one probably needs more.
- lower extension and SPL, the driver "sees" a larger equivalent baffle
- "good" mass loading - one can search for a compromise in the back wings length w.r.t. quarter wave resonance, mass loading and SPL.
- lower space requirements (one has a front baffle with inward wings)
While there are reasons for not using inward "wings" in a fullrage OB, I see no problem with that for low frequency (mine are crossed over at 160Hz LR4). For music, I don't feel the need of more SPL or extension and the bass is powerful, clean and tight(yes, midbass also).
For HT...I wouldn't know, but one probably needs more.
Hi Rudolph, ...
First of all, please understand that this set of measurements are just to confirm what I was hearing, .. and not the absolute truth in themselves. That said, ..
Q. Did you measure all three configurations at the same position in the room? What was the mic distance?
Mic distance was around 2 m with mic located at listening position . As I mentioned before, the ripole was a bit closer (around 0.5 m) than the other designs. The locations were a bit different (see my photos - the ripole somewhat closer to the side wall), .. as I don't have a lot of space in the room at this point. For all these expts, .. the horn sub in the background was made irrelevant by blocking off its mouth with the floor.
Q. Did you compare the cone excursion at the same SPL level between the "ripole" and the other configurations? The "ripole" may have been less efficient due to mass loading, but should do the same SPL level with less cone movement. Since dipoles are almost always limited by xmax first and not by power, the "ripole" may have been the winner at max SPL without power considerations.
Yes,.. comparatively, the ripole had less cone excursion, I would agree with you that it would probably have a higher power handling / max SPL. However, I still prefer the bass from the W baffle subjectively WITH THIS DRIVER .
From my little experience, I feel fairly confident that a more powerful amplifier AND / OR a driver with a stronger magnet will yield better results with ripoles.
Thanks
First of all, please understand that this set of measurements are just to confirm what I was hearing, .. and not the absolute truth in themselves. That said, ..
Q. Did you measure all three configurations at the same position in the room? What was the mic distance?
Mic distance was around 2 m with mic located at listening position . As I mentioned before, the ripole was a bit closer (around 0.5 m) than the other designs. The locations were a bit different (see my photos - the ripole somewhat closer to the side wall), .. as I don't have a lot of space in the room at this point. For all these expts, .. the horn sub in the background was made irrelevant by blocking off its mouth with the floor.
Q. Did you compare the cone excursion at the same SPL level between the "ripole" and the other configurations? The "ripole" may have been less efficient due to mass loading, but should do the same SPL level with less cone movement. Since dipoles are almost always limited by xmax first and not by power, the "ripole" may have been the winner at max SPL without power considerations.
Yes,.. comparatively, the ripole had less cone excursion, I would agree with you that it would probably have a higher power handling / max SPL. However, I still prefer the bass from the W baffle subjectively WITH THIS DRIVER .
From my little experience, I feel fairly confident that a more powerful amplifier AND / OR a driver with a stronger magnet will yield better results with ripoles.
Thanks
Assuming that the question was adressed to me:
- Front baffle : 46x46 cm (one could make it actually smaller)
- total depth : 32 cm
- rear opening width: 25 cm (I think I would make this a bit wider though , about 30cm. Anyway, not critical)
- rear opening depth (straight portion): 11 cm
Top and bottom are parrallel and so are the rear opening lateral walls (which continue the sloped wings). If enough woodworking skills and tools are present, one could make curved wings that slope inwards and the continue straight.
Interestigly, my units sound best with no stuffing whatsoever. I tried some stuffing to help damp the quarter wave resonance, but this took a lot of the extension and "life-like" away, so I gave up and removed the resonance electronically with a notch filter(at about 260 Hz, which is out of band, but was still audible).
The problem is that stuffing should behave resistive, which is kinda hard: one could use materials like steel wool. With acoustic resistor, the respunse would be closer to a cardioid.
- Front baffle : 46x46 cm (one could make it actually smaller)
- total depth : 32 cm
- rear opening width: 25 cm (I think I would make this a bit wider though , about 30cm. Anyway, not critical)
- rear opening depth (straight portion): 11 cm
Top and bottom are parrallel and so are the rear opening lateral walls (which continue the sloped wings). If enough woodworking skills and tools are present, one could make curved wings that slope inwards and the continue straight.
Interestigly, my units sound best with no stuffing whatsoever. I tried some stuffing to help damp the quarter wave resonance, but this took a lot of the extension and "life-like" away, so I gave up and removed the resonance electronically with a notch filter(at about 260 Hz, which is out of band, but was still audible).
The problem is that stuffing should behave resistive, which is kinda hard: one could use materials like steel wool. With acoustic resistor, the respunse would be closer to a cardioid.
Sorry bzfcocon ,
That question was addressed to you.
Thanks for your reply. I've been making up plans to build my dipole sub but wasn't able to decide which one would best suit my needs . Your preferences seem to coincide with mine and you feel the Y does the job.
I'll try it out as it's easy to do.
I guess you meant curved sloping sides to spread out and flatten the resonance peak. There must be some other way to kill it .
I'll try the straight sides first. Will post results when it is done.
Can you put up a picture ?
Thanks.
That question was addressed to you.
Thanks for your reply. I've been making up plans to build my dipole sub but wasn't able to decide which one would best suit my needs . Your preferences seem to coincide with mine and you feel the Y does the job.
I'll try it out as it's easy to do.
I guess you meant curved sloping sides to spread out and flatten the resonance peak. There must be some other way to kill it .
I'll try the straight sides first. Will post results when it is done.
Can you put up a picture ?
Thanks.
ashok said:
Yeah, well, I don't know if curved sides REALLY help much, it's rather an aesthetical issue. The resonance will still be present, but one can at least push it out of band (by using a reasonable depth)
Here's a picture of mine:
Looks like I cannot attach it, although is small enough. I'll try again later.
Well, I'm kind of disappointed the ripoles didn't turn out as expected. Not only because I suggested the drivers, but also because I had high hopes as well.
Maybe a more traditional N baffle with larger openings would be better. I have plenty of amp power available so that it no concern.
BTW, for hosting pics...
Imageshack =
Tinypic =
Maybe a more traditional N baffle with larger openings would be better. I have plenty of amp power available so that it no concern.
BTW, for hosting pics...
Imageshack =
Tinypic =
Thanks bzfcocon, that's just as I imagined it to be.
Are there any equations that can calculate the response of such an enclosure ? The rear enclosure must be acting as a resistive load . Would that be acting like an acoustic transformer ?
In an extreme case it would end up being just a Helmholtz resonator I guess.
Are there any equations that can calculate the response of such an enclosure ? The rear enclosure must be acting as a resistive load . Would that be acting like an acoustic transformer ?
In an extreme case it would end up being just a Helmholtz resonator I guess.
Unfortunately, I could not find any theory specifically on Y Frames. There was a project in a german magazine that inspired me, but they presented the whole as if only the pure dipole theory was applicable and ignored even the quarter wave resonance, which IS there (but they stuffed the rear cavity).
I agree with you that the rear cavity should be resistive. However, I guess the introduced effect and phase shift is quite weak and the response still resembles that of a dipole. That U-Frames are stuffing sensitive and how to stuff them properly is teached here (same would apply to Y-baffles, i think):
http://www.musicanddesign.com/u_frame.html
However, as I mentioned before, I liked it better with no stuffing at all. I admit I did not try the "proper" way because I could not measure.
I agree with you that the rear cavity should be resistive. However, I guess the introduced effect and phase shift is quite weak and the response still resembles that of a dipole. That U-Frames are stuffing sensitive and how to stuff them properly is teached here (same would apply to Y-baffles, i think):
http://www.musicanddesign.com/u_frame.html
However, as I mentioned before, I liked it better with no stuffing at all. I admit I did not try the "proper" way because I could not measure.
To trim or not to trim
Should I make this a hybrid W-U baffle by letting the wings extend beyond the "V" and stuff the cavity or should I truncate it at or near the "V" . Any practical advice from people who've tried both alternatives?
Also, would I benefit from making the wings unequal lengths?
Should I make this a hybrid W-U baffle by letting the wings extend beyond the "V" and stuff the cavity or should I truncate it at or near the "V" . Any practical advice from people who've tried both alternatives?
Also, would I benefit from making the wings unequal lengths?
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