My Vifa went back. Still in some limbo with the decision.
This, and the link to the Muse sub have got me thinking.
I rather like the idea of the dual drivers with a middle slot. Push Push. Pair of 10 inch drivers. Have heard good things about this arrangement. Works out well with my desire to hide the drivers from sight and still be able to place the sub close to a wall (trying to avoid rear firing).
Side panel removed...
Sealed. Bit of extra carpentry, but not too bad. Would be much easier on myself if I just placed the baffles in at right angles, but the diagonal placement would add significantly to the structural rigidity and possibly even tame the resonant cavities. Driver cones directly opposite one another. That's not a passive radiator in there. I'm just too lazy to draw the motor assembly.
A pair of those SD315A-88 12 for 90 USD certainly is a nice price.
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=295-488
The 7mm xmax is less of a handicap in a sealed dual driver arrangement no?
Other driver suggestions?
This, and the link to the Muse sub have got me thinking.
I rather like the idea of the dual drivers with a middle slot. Push Push. Pair of 10 inch drivers. Have heard good things about this arrangement. Works out well with my desire to hide the drivers from sight and still be able to place the sub close to a wall (trying to avoid rear firing).
Side panel removed...
Sealed. Bit of extra carpentry, but not too bad. Would be much easier on myself if I just placed the baffles in at right angles, but the diagonal placement would add significantly to the structural rigidity and possibly even tame the resonant cavities. Driver cones directly opposite one another. That's not a passive radiator in there. I'm just too lazy to draw the motor assembly.
A pair of those SD315A-88 12 for 90 USD certainly is a nice price.
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=295-488
The 7mm xmax is less of a handicap in a sealed dual driver arrangement no?
Other driver suggestions?
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using two drivers in a ppsl sealed setup will limit excursion nicely. You'd be fine to ~108db -50hz with two sd315a-88. I'm assuming you've read this http://www.diyaudio.com/forums/subwoofers/177905-thread-those-interested-ppsl-enclosures.html
although, I wouldn't want you to over-think anything
I like that ppsl design you posted above.
later,
rev.
although, I wouldn't want you to over-think anything
I like that ppsl design you posted above.
later,
rev.
Hi peace brainerd,
The layout you presented in Post #41 is your best yet.
As to PPSL, by djk's definition it's only a PPSL if you turn one of the drivers around. It also seems to be easy to get the plenum (loading slot) too big, even the rear corners in the slot can be filled in to reduce the volume, and as to the opening: it does not have to be larger than 50% - 70% of the combined Sd of the two drivers. Basically, just large enough to enable driver mounting.
The thread revboden referenced in Post #42 has a lot of good information. I'll attach a post by djk from the High Efficiency Speaker Asylum.
Regards,
The layout you presented in Post #41 is your best yet.
As to PPSL, by djk's definition it's only a PPSL if you turn one of the drivers around. It also seems to be easy to get the plenum (loading slot) too big, even the rear corners in the slot can be filled in to reduce the volume, and as to the opening: it does not have to be larger than 50% - 70% of the combined Sd of the two drivers. Basically, just large enough to enable driver mounting.
The thread revboden referenced in Post #42 has a lot of good information. I'll attach a post by djk from the High Efficiency Speaker Asylum.
Regards,
I'm trying to get the gist of this and have posted at techtalk as well. Why does reversing the frame, and then reversing polarity, turn the application into "push-pull"? It just seems confusing. The cones are still both "pushing" into the slot on any coincident signal... no? So the action is still "push-push" with the exception that the one cone is reversed. It's just an alternative push-push arrangement.... no?
I hope I can get this figured straight. It's driving me nuts.
I hope I can get this figured straight. It's driving me nuts.
Hi peace brainerd,
You are correct, both cones have to push into the slot at the same time, etc.. If the definition of Push is the driver's cone moving forward, and the definition of Pull is the cone moving backwards, then the PPSL arrangement would be Push Pull (one is pushing while the other one is pulling). Anyhow it's djk's design, and the name he has chosen.
Regards,
You are correct, both cones have to push into the slot at the same time, etc.. If the definition of Push is the driver's cone moving forward, and the definition of Pull is the cone moving backwards, then the PPSL arrangement would be Push Pull (one is pushing while the other one is pulling). Anyhow it's djk's design, and the name he has chosen.
Regards,
"It's just an alternative push-push arrangement.... no? "
That's correct.
In the late 70s there was a company that made a system with one reverse mounted driver they described as 'push-pull'. It made a certain amount of sense as one cone was pushing itself outwards in its frame while the other driver was pulling its cone into its frame.
The above system was co-planar, the drivers were both mounted in the same plane.
I got the idea to mount them in a plenum, or slot. So that's where the term PPSL came from.
That's correct.
In the late 70s there was a company that made a system with one reverse mounted driver they described as 'push-pull'. It made a certain amount of sense as one cone was pushing itself outwards in its frame while the other driver was pulling its cone into its frame.
The above system was co-planar, the drivers were both mounted in the same plane.
I got the idea to mount them in a plenum, or slot. So that's where the term PPSL came from.
An externally hosted image should be here but it was not working when we last tested it.
Those drivers need to be squeezed closer together in that arrangement?
djk... my contribution is somewhat limited to ideas and graphics. And I'm deeply obliged to you for the lead in this direction. But I've yet to gain any expertise in modeling software. Hint hint.
I wonder if you'd crunch a few numbers for a push-pull sealed project for two or three of the more popular drivers? Plenum/slot cubic inch. Sealed cavity cubic inch.
Maybe the ...
Dayton RSS315HO-4
Peerless 830500
(or the 10 inch versions if either of them are better suited)
...
And, ideally, some even better value out there, including car audio drivers. that specs well for this application, minus the cast basket and fancy cone material. Got to believe that there are some great candidates out there for half this price. Hell, there's so much rebadged stuff from the same plant in China nowadays anyway. A very large factor of of DIY for me is "bang for the buck". I'd love to be able to see a project like this for 150 dollars in drivers and 150 dollars in amplifier.
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[/QUOTE] A very large factor of of DIY for me is "bang for the buck". I'd love to be able to see a project like this for 150 dollars in drivers and 150 dollars in amplifier.[/QUOTE]
Hmm.
You want good AND cheap?
Well, OK then!
Check these out:
Dayton Audio SD270A-88 10" DVC Subwoofer from Parts Express Part # 295-486
Dual voice coils allow you to run the paralleled voice coils for each woofer at 4 Ohms
If you further connected them in parallel, the load would be 2 ohms, too low for most amps.... BUT... there is a clever and highly cost effective alternative:
For a really good and inexpensive amp to drive these, try the Sure 2x100W @ 4 Ohm TK2050 Class-D Audio Amplifier Board, also at Parts Express, part number 320-300
You would use ONE channel for EACH woofer running at 4 Ohms
It will put out a solid 80W with very low THD into 4 Ohms (they say 100W but the THD is much higher at that point, still it's quite usable past 100W).
Again, you use one amp channel per DVC woofer... and wind up with a true 200W subwoofer amp for $39... and you won't believe how SOLID the bass is with these little class-d amps. Tight, with terrific slam and impact.
I would use a sealed box with about a 3 cub ft interior, although 2ft3 would work well also. Anechoically, the speakers would start rolling off in the mid 50's which works very well with most rooms resonances and the "room gain", so that in most average size rooms, even as big as 12x20 or more, the actual in room response could easily reach the low 30's
And with 100 W driving each woofer, it'll play very, very loud and clean! I guesstimate max SPL at about 113 to 115dB at 1m
Vented box would require about 6 to 8 cub ft and may be too much for most rooms as the bass would be anechoically flat down to about 28 Hz or so.
So if you like saving bucks, this could be a nice starting point, $64 for the woofers, and $39 for the amp (+$48 for the power supply Part # 320-316)... you're looking at $151 so shipping is free... And although I don't work for them I'm really pleased with Parts Express for bringing us this good stuff at DIY accessible prices.
And, you'll need a crossover for the sub unless your receiver or amplifier has a filtered sub-out...
Not bad for half the budget you were considering.
Best of Luck
Hmm.
You want good AND cheap?
Well, OK then!
Check these out:
Dayton Audio SD270A-88 10" DVC Subwoofer from Parts Express Part # 295-486
Dual voice coils allow you to run the paralleled voice coils for each woofer at 4 Ohms
If you further connected them in parallel, the load would be 2 ohms, too low for most amps.... BUT... there is a clever and highly cost effective alternative:
For a really good and inexpensive amp to drive these, try the Sure 2x100W @ 4 Ohm TK2050 Class-D Audio Amplifier Board, also at Parts Express, part number 320-300
You would use ONE channel for EACH woofer running at 4 Ohms
It will put out a solid 80W with very low THD into 4 Ohms (they say 100W but the THD is much higher at that point, still it's quite usable past 100W).
Again, you use one amp channel per DVC woofer... and wind up with a true 200W subwoofer amp for $39... and you won't believe how SOLID the bass is with these little class-d amps. Tight, with terrific slam and impact.
I would use a sealed box with about a 3 cub ft interior, although 2ft3 would work well also. Anechoically, the speakers would start rolling off in the mid 50's which works very well with most rooms resonances and the "room gain", so that in most average size rooms, even as big as 12x20 or more, the actual in room response could easily reach the low 30's
And with 100 W driving each woofer, it'll play very, very loud and clean! I guesstimate max SPL at about 113 to 115dB at 1m
Vented box would require about 6 to 8 cub ft and may be too much for most rooms as the bass would be anechoically flat down to about 28 Hz or so.
So if you like saving bucks, this could be a nice starting point, $64 for the woofers, and $39 for the amp (+$48 for the power supply Part # 320-316)... you're looking at $151 so shipping is free... And although I don't work for them I'm really pleased with Parts Express for bringing us this good stuff at DIY accessible prices.
And, you'll need a crossover for the sub unless your receiver or amplifier has a filtered sub-out...
Not bad for half the budget you were considering.
Best of Luck
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Quite right. I was thinking of keeping those two bottom triangle panels removable but, as you point out, there is no good reason to if I just mount both drivers on the facings.
Isn't 6mm xmax going to be a considerable restraint even in a sealed push-pull arrangement?
I looked through partsexpress page dedicated to car audio subs and didn't see anything that really stood out as a bargain.
For the time being I'm most interested in the RSS265HO-4 10" or the RSS315HF-4 12". Unless I could just as well use the 8 ohm versions in this dual driver arrangement? That would cut 40 dollars off the bill.
I'm generally turned off by any marketing hype where sub drivers are concerned. If I can identify a driver with suitable TS specs with some recognizable brand name/reputation I could give a rip if it's car audio, or has a hezacone, mineral filled, space-aged-spooge cone, quadruple shorting rings, super hetrodynamic pentatech whiz bang and finite element analysis dohicky. Stamped steel frame? All the better. Put the money where it counts, thank you. Draw the line at foam surrounds. Don't know why. I've still got drivers from the early 70's with perfect rubber surrounds. Never had a single foam surround last more than a decade. New technology foam is supposed to be superior in this regard. I'll let someone else experiment with that.
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An externally hosted image should be here but it was not working when we last tested it.
It appears that a volume control pot or rotary encoder board and a DC power supply are req'd. That raises the cost a little bit. Many tinkerers, like myself, have those things just laying about the shop. A 30vdc SMPS can be found at most goodwills on any day for less than five bucks in their electronics accessories cardboard box full of various pc, printer, etc transformers. I'm not sure if a 4 to 6 amp SWPS would be sufficient for this though. The supply that is most recommended for this job is the Sure 24 VDC 14.6A 350W Regulated Switching Power Supply 320-316 which adds 48 dollars to the bill. A toroidal transformer, as indicated in the image above, is approx the same, or more, and requires a little extra circuitry to integrate. Throw in a new volume/level control and it's edging up toward the price of a ready to go subwoofer plate amp with level/phase/crossover controls already in place.
That said, I read the reviews on that amp and I'm warming to the idea of getting one to add to the mix of integrated amps I use. I really am a cheap bastard and bargains are a very big part of the enjoyment of diy. Most of what I own is from second hand stores, garage sales, auctions. That includes a few "vintage" era Hitachi, NAD, and other 70's and 80's era stuff. It's generally fantastic equipment for the price. I just love it when someone garage sales an otherwise mint integrated for 5 dollars because one of the channels has gone out. 90 percent of the time the panel switches and pots just need cleaning and it's good to go for another 20 yrs. I usually install a small muffin fan at half voltage (almost silent running) above the transistor heat sinks like they all should have had in the first place.
Anyway, That Sure amp you refer to looks like it'd be an excellent way to own a new technology amp almost guilt free (for a cheap bastard like myself). Especially since I already have a lot of dc power supplies laying around.
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"Generally speaking, with PPSL, the magnet ought to be just about as close to the other woofer as comfortable margin allows?"
That's true for for Midrange response, it kind of doesn't matter for Subwoofer use. Whatever works well for you should be OK.
You could reduce the cavity volume to a minimum by narrowing up the slot area to the Sd of one driver, and mount the drivers through a removable panel, allow for cone-to-driver clearance if you try this (I don't generally use removable panels).
That's true for for Midrange response, it kind of doesn't matter for Subwoofer use. Whatever works well for you should be OK.
You could reduce the cavity volume to a minimum by narrowing up the slot area to the Sd of one driver, and mount the drivers through a removable panel, allow for cone-to-driver clearance if you try this (I don't generally use removable panels).
Funny you mention that..., this is my shop subwoofer. JBL GT1041D car sub in a .75 cu ft sealed box. Just sits on a shelf about a foot away from and facing the wall where it seems to integrate best in my concrete block walled workshop.
Was in my Honda Civic 15 years ago and I lost interest in car stereo. Took out the sub and stuck it on a workshop shelf and was fairly pleased with the result.
The heavy poly cone does sound a bit tupperware-thumpy when you snap it with your fingernail. Different cones do sound notably different subjected to this highly scientific analysis. Don't know how that translates to the sound reproduction in real use. But two of these might be decent candidates, as far as build quality, xmax (12mm), and well regarded brand.
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CS1214 is a nice looking no-nonsense 12inch 12mm xmax subwoofer.
Amazon link below for 120 dollars a pair. Tax free and free ship. Amazon is great for customer service and product returns.
JBL CS1214 CS Series Subwoofer - 12, 1000 Watt Total, 90db Sensitivity
Here's Harmon's online store.
Harman Audio - CS1214
And, it took a bit of work, but I located the TS parameters and box recommendations
http://www.stereoauto.it/manuali/jbl cs1214 specifiche.pdf
The 10 inch version is less yet. But no free ship indicated.
http://www.amazon.com/JBL-CS1014-Wo...1?s=electronics&ie=UTF8&qid=1320275255&sr=1-1
....and cannot find TS parameters for it. But that magnet and relatively smaller rubber surround makes me think it's nowhere near xmax of the 12 inch version.
Amazon link below for 120 dollars a pair. Tax free and free ship. Amazon is great for customer service and product returns.
JBL CS1214 CS Series Subwoofer - 12, 1000 Watt Total, 90db Sensitivity
Here's Harmon's online store.
Harman Audio - CS1214
And, it took a bit of work, but I located the TS parameters and box recommendations
http://www.stereoauto.it/manuali/jbl cs1214 specifiche.pdf
The 10 inch version is less yet. But no free ship indicated.
http://www.amazon.com/JBL-CS1014-Wo...1?s=electronics&ie=UTF8&qid=1320275255&sr=1-1
....and cannot find TS parameters for it. But that magnet and relatively smaller rubber surround makes me think it's nowhere near xmax of the 12 inch version.
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