Figured I would post a picture just for the heck of it. PR's are not horribly cheap, so may have to go the ported route for my first PPSL. I also don't have a small scale (to weigh the weights I need to tune the PR) at the moment. Another cost I have to figure in designing a PR cabinet design.
Did you notice any difference in sound with PR vs ports? I know some people don't like them. I am indifferent as I have had speakers with them and they sounded fine to me.
Thanks for discussing the slot ratios. I had forgotten about that. 2:1 means the slot is half the area of the total woofer SD? That's the minumum? DJK, what's the smallest slot you have made?
Did you notice any difference in sound with PR vs ports? I know some people don't like them. I am indifferent as I have had speakers with them and they sounded fine to me.
Thanks for discussing the slot ratios. I had forgotten about that. 2:1 means the slot is half the area of the total woofer SD? That's the minumum? DJK, what's the smallest slot you have made?
Attachments
Hi djk,
Post #285: "...DJK, what's the smallest slot you have made?"
That sounds like a good question. How about the aspect ration of the slot? Have you done any experimentes with that? Especially considering mounting from inside the box it would be quite possible to come up with very slot-like plenum openings.
Regards,
Post #285: "...DJK, what's the smallest slot you have made?"
That sounds like a good question. How about the aspect ration of the slot? Have you done any experimentes with that? Especially considering mounting from inside the box it would be quite possible to come up with very slot-like plenum openings.
Regards,
"...DJK, what's the smallest slot you have made?"
My first prototype was 3.24:1, later I switched to 2:1 for convienence of construction.
I was alarmed at how much pressure I was getting with the first prototype, but in retrospect it was nothing in comparison with a typical compression driver and its 10:1 compression ratio.
NP in his slot-loaded OB speaker measured a 2.78dB gain with a 3:1 ratio. I have not tried to verify this with my PPSL. Art Welter thinks there may be some mass loading from the narrow slot and the wide front baffle. I can tell you that many times people talk to the FOH engineer at a gig about these, and take pictures too.
My first prototype was 3.24:1, later I switched to 2:1 for convienence of construction.
I was alarmed at how much pressure I was getting with the first prototype, but in retrospect it was nothing in comparison with a typical compression driver and its 10:1 compression ratio.
NP in his slot-loaded OB speaker measured a 2.78dB gain with a 3:1 ratio. I have not tried to verify this with my PPSL. Art Welter thinks there may be some mass loading from the narrow slot and the wide front baffle. I can tell you that many times people talk to the FOH engineer at a gig about these, and take pictures too.
I have seen Nelson Pass use rounded plenums on the back side of his non PP slot loaded set ups, some have done 45 degree angles with or without a flare going towards opening, and of course old fashioned square box plenums.
Has any testing been done to determine any advantages over the various styles and shapes of plenums and thier openings? And of course, is it necessary to do any major rounding/flaring of opening to reduce port noise as with BR? If I had wood tools and money (measuring equipment) I would experiment
Some day, maybe...
For now, I plan on trying to keep it as simple as possible (it's just a bass reflex or sealed enclosure with added PP plenum).
Has any testing been done to determine any advantages over the various styles and shapes of plenums and thier openings? And of course, is it necessary to do any major rounding/flaring of opening to reduce port noise as with BR? If I had wood tools and money (measuring equipment) I would experiment
Some day, maybe...For now, I plan on trying to keep it as simple as possible (it's just a bass reflex or sealed enclosure with added PP plenum).
angled plenum
This was my 2nd attempt ppsl. In this case I used a very small plenum with angled walls. Granted, i did not do any case vs case measurements, but the system in the pics has relatively flat response all the way up to 800Hz.
(note the pics only show the partial internal plenum, without any surrounding enclosure... i built in inside first)
This was my 2nd attempt ppsl. In this case I used a very small plenum with angled walls. Granted, i did not do any case vs case measurements, but the system in the pics has relatively flat response all the way up to 800Hz.
(note the pics only show the partial internal plenum, without any surrounding enclosure... i built in inside first)
Attachments
Scott, what made you decide on a deeper plenum (hornresp modeling)? Would making it more shallow effect the sound? I would be curious to see various testing on plenums.
I am happy to hear you guys are getting higher flat response than TH's, folded horns and the like. I need a sub that can go reasonably deep (I only care about music at this point so 25-30 is ok), but also cross over higher than 100 if I decide to fool around with crossover points...
I guess I should build something and figure it out on my own, right?
I am happy to hear you guys are getting higher flat response than TH's, folded horns and the like. I need a sub that can go reasonably deep (I only care about music at this point so 25-30 is ok), but also cross over higher than 100 if I decide to fool around with crossover points...
I guess I should build something and figure it out on my own, right?
plenum
Hi Tim,
When you have plenty of time, read the whole thread: beginning to current.
This particular ppsl is the motor to drive a mid-bass horn, and the apex of the ppsl is stuffed with acoustic. IMO the beauty of the ppsl principle is that it is versatile. I have limited experience compared to others, but I think the real virtue of this design is a woofer (sub?)-woofer section of an active system.
I think a decade is the limit, so for an F3 of 25, think 250 Hz tops, and probably better off running only to about 125 Hz.
I really don't understand tapped horns- they don't make a bit of sense to me, but a ppsl is a true gem. I personally audtioned a pair built by Les Hudson
(while I was down at Axpona, in Atlanta, and they were truely remarkable.
... And yes, I would encourage you to build. I place a whole lot more value on creating saw dust than I do running "sims". Happy Listening
Scott, what made you decide on a deeper plenum (hornresp modeling)? Would making it more shallow effect the sound? I would be curious to see various testing on plenums.
I am happy to hear you guys are getting higher flat response than TH's, folded horns and the like. I need a sub that can go reasonably deep (I only care about music at this point so 25-30 is ok), but also cross over higher than 100 if I decide to fool around with crossover points...
I guess I should build something and figure it out on my own, right?
Hi Tim,
When you have plenty of time, read the whole thread: beginning to current.
This particular ppsl is the motor to drive a mid-bass horn, and the apex of the ppsl is stuffed with acoustic. IMO the beauty of the ppsl principle is that it is versatile. I have limited experience compared to others, but I think the real virtue of this design is a woofer (sub?)-woofer section of an active system.
I think a decade is the limit, so for an F3 of 25, think 250 Hz tops, and probably better off running only to about 125 Hz.
I really don't understand tapped horns- they don't make a bit of sense to me, but a ppsl is a true gem. I personally audtioned a pair built by Les Hudson
(while I was down at Axpona, in Atlanta, and they were truely remarkable.
... And yes, I would encourage you to build. I place a whole lot more value on creating saw dust than I do running "sims". Happy Listening
Still would be helpful
I'm poised with saw in hand but having a tough time trying to model the details that DjK provides for various speakers from BBPro into an actual box using the same software. Maybe I don't know how to use the software, but I am not able to get it to produce useable box sizes-it keeps making one dimension too small to fit the 15" JBL 2226h drivers. Is there some trick to forcing the software to hold 2 of 3 dimensions and add the 3rd to = the chosen Vb? Also, am I supposed to subtract the vol of the plenum from the box total Vb? Or could someone just model this in BBpro and send the file to me? thanks.
I'm poised with saw in hand but having a tough time trying to model the details that DjK provides for various speakers from BBPro into an actual box using the same software. Maybe I don't know how to use the software, but I am not able to get it to produce useable box sizes-it keeps making one dimension too small to fit the 15" JBL 2226h drivers. Is there some trick to forcing the software to hold 2 of 3 dimensions and add the 3rd to = the chosen Vb? Also, am I supposed to subtract the vol of the plenum from the box total Vb? Or could someone just model this in BBpro and send the file to me? thanks.
i am wondering has anyone tried PPSL approach with smaller drivers - 8" or 10" that plays deep into 20s? i'm a bit paranoid about bass overpowering my smallish room - 22m2, 3.3m ceiling - and on top i think there was a commercial loudspeaker manufacturer (from ukraine methinks) at munich audio fair with a 3 way speakers incorporating a PPSL box with 2x8" inside
what i've found so far is a dayton cheap woofer with 7mm Xmax with 27 Hz Fs and a .37 Qts though low efficency (around 88db/w)
Dayton RS225S-8 8" Reference Shielded Woofer 8 295-366
is there anything with a higher efficiency that would suit PPSL and still go deep? anyone tried to built a smaller PPSL?
what i've found so far is a dayton cheap woofer with 7mm Xmax with 27 Hz Fs and a .37 Qts though low efficency (around 88db/w)
Dayton RS225S-8 8" Reference Shielded Woofer 8 295-366
is there anything with a higher efficiency that would suit PPSL and still go deep? anyone tried to built a smaller PPSL?
"is there anything with a higher efficiency that would suit PPSL and still go deep? anyone tried to built a smaller PPSL? "
I've built a double 8 shielded PPSL that was a stand for a CRT TV. It worked fine within the limits of the cabinet size and driver capabilities.
AudioPro used to sell a PP dual 6=1/2" design (not SL), very limited output capability.
Loudandproud musik med nrvaro
I've built a double 8 shielded PPSL that was a stand for a CRT TV. It worked fine within the limits of the cabinet size and driver capabilities.
AudioPro used to sell a PP dual 6=1/2" design (not SL), very limited output capability.
An externally hosted image should be here but it was not working when we last tested it.
Loudandproud musik med nrvaro
What are your true feelings on the recent talk I have been reading that some people don't like the PPSL's due to the 3rd order harmonics becoming more audible due to reduction of 2nd order, and better woofers don't need slot loading? I see talk, but have not done a lot of reading on the claims. I don't know know much about all the different types of harmonics and whatnot enough to care at the moment. I am mainly interested in the enclosure motion cancelling design of push push and PPSL cabinets.... I also don't currently have testing equipment to argue such points, either
Ken Kresiel just jumped back into the fray with a new line of 'push - pull' subwoofers.
Welcome to the KEN KREISEL Sound Store
Welcome to the KEN KREISEL Sound Store
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This has 4 8"
An externally hosted image should be here but it was not working when we last tested it.
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