Long time reader, first time poster...
I am woodworker mostly, amongst other things, but I do have some experience fiddling with audio equipment. And I now have a project in mind that will probably get some audiophile toes curling.
Over the years Ive been given and collecting odds and ends, and the time has come to try and bodge them into some sort of PA system for parties and festivals (I also do a spot of DJing), or get rid.
Im under no illusion that the results will not be high end, but I would like to get the best I can out of what I have, if it is worthwhile. Most of what I have has cost nothing, so if it all blows up fairly soon I will only have wasted some time, and hopefully learnt some lessons.
I have a workshop and the materials and the know-how to physically assemble cabinets in no time, and only need to fork out for a few components really. However, I do not pretend to know a huge deal about the technical biz!
I have recently been given a pair of Community Speakers CSX70-S2's and Im thinking of using them as a starting point. The cabs are fairly beaten up but they work fine, not that they get very kind reviews... powerful but a bit harsh, seems to be the concensus.
see here: http://www.communitypro.com/sites/default/files/CSX70-S2_spec.pdf
Rebuilding the cabs, I dont suppose I can make a huge different to the sound, but I can definitely make them look a lot purdier, they are currently hideous.
I was also given, a longer time ago, two 2-way cabinets of the same wattage, 15" and horn tweeters, but different makes - one martin audio and one made by Turbosound. As far as I remember these all work, crossovers too.
I have a few others things, including four more mystery (probably rubbish) 12's, but i think ill stick to the branded stuff for now!
So, I thought I might rebuild the Community cabinets, maybe modifying the design (if anyone has any suggestions?) reusing everything except maybe replacing the tweeters (read complaints about them) with the (not matching!) tweeter units from the Turbosound/Martin audio, which I am just wildly guessing will work and be better.
I could then use the two (also not matching) TS and Martin 15"s to make a dual bass unit to go in between for extra oomph when neccesary/appropriate.
Last but not least I was thinking it could be an option to buy amp modules to go in each one, to make them easier to manage. These would be the only real outlay.
How many rules am I breaking? Is this utter madness? Will they just sound ear-bleedingly terrible? Should I close my account and never come back here to the forums again?
The alternative is trying to sell everything (cant imagine Id get much) and putting the money towards some decent drivers and building something worthwhile. Sounds sensible, doesnt sound as fun...
Somebody stop me before i do something I regret!
I am woodworker mostly, amongst other things, but I do have some experience fiddling with audio equipment. And I now have a project in mind that will probably get some audiophile toes curling.
Over the years Ive been given and collecting odds and ends, and the time has come to try and bodge them into some sort of PA system for parties and festivals (I also do a spot of DJing), or get rid.
Im under no illusion that the results will not be high end, but I would like to get the best I can out of what I have, if it is worthwhile. Most of what I have has cost nothing, so if it all blows up fairly soon I will only have wasted some time, and hopefully learnt some lessons.
I have a workshop and the materials and the know-how to physically assemble cabinets in no time, and only need to fork out for a few components really. However, I do not pretend to know a huge deal about the technical biz!
I have recently been given a pair of Community Speakers CSX70-S2's and Im thinking of using them as a starting point. The cabs are fairly beaten up but they work fine, not that they get very kind reviews... powerful but a bit harsh, seems to be the concensus.
see here: http://www.communitypro.com/sites/default/files/CSX70-S2_spec.pdf
Rebuilding the cabs, I dont suppose I can make a huge different to the sound, but I can definitely make them look a lot purdier, they are currently hideous.
I was also given, a longer time ago, two 2-way cabinets of the same wattage, 15" and horn tweeters, but different makes - one martin audio and one made by Turbosound. As far as I remember these all work, crossovers too.
I have a few others things, including four more mystery (probably rubbish) 12's, but i think ill stick to the branded stuff for now!
So, I thought I might rebuild the Community cabinets, maybe modifying the design (if anyone has any suggestions?) reusing everything except maybe replacing the tweeters (read complaints about them) with the (not matching!) tweeter units from the Turbosound/Martin audio, which I am just wildly guessing will work and be better.
I could then use the two (also not matching) TS and Martin 15"s to make a dual bass unit to go in between for extra oomph when neccesary/appropriate.
Last but not least I was thinking it could be an option to buy amp modules to go in each one, to make them easier to manage. These would be the only real outlay.
How many rules am I breaking? Is this utter madness? Will they just sound ear-bleedingly terrible? Should I close my account and never come back here to the forums again?
The alternative is trying to sell everything (cant imagine Id get much) and putting the money towards some decent drivers and building something worthwhile. Sounds sensible, doesnt sound as fun...
Somebody stop me before i do something I regret!
Community made a bunch of different cabinets like this back in the day, they were efficient and got loud but light weight wasn't part of the program and apparently they didn't get the memo about not arranging drivers side by side.
So if it were me I'd build some double 12" + horn cabs with the 12's stacked vertically and if you use a passive crossover maybe experiment with an active crossover first to see what frequency produces the cleanest output for the drivers being used. It will probably be a bit higher than optimal(1khz) but the worst thing you can do for clarity is force a compression driver to play lower than it likes to.
Speaking of active crossovers, just looking at the response curve for those Communities I can see a whole lot of stuff that could be done better with a modern DSP processor like the Behringer DCX2496, that peak at 4khz for example would undoubtedly make these things an ear bleedingly sharp experience and those rippled notches between 400 and 1khz are a result of comb filtering between the four 12's.
So if it were me I'd build some double 12" + horn cabs with the 12's stacked vertically and if you use a passive crossover maybe experiment with an active crossover first to see what frequency produces the cleanest output for the drivers being used. It will probably be a bit higher than optimal(1khz) but the worst thing you can do for clarity is force a compression driver to play lower than it likes to.
Speaking of active crossovers, just looking at the response curve for those Communities I can see a whole lot of stuff that could be done better with a modern DSP processor like the Behringer DCX2496, that peak at 4khz for example would undoubtedly make these things an ear bleedingly sharp experience and those rippled notches between 400 and 1khz are a result of comb filtering between the four 12's.
thanks for the response, food for thought.
Say they became double 12 + horns, that would leave me four more 12s. Could I try them as two more doubles with the horns from the Turbosound and Martin cabs?
that would neatly leave me the 15s for a bass bin.
would you consider the possibe results worthy of purchasing a DSP such as the one you mention?
the thought of spending any significant amount of money hurts a bit (at the moment at least) but by the sounds of it the other major weak link is the crossovers, but without an active to test them out it would be hard to know what passive setup to go for which does start to get me thinking I might be better off selling up and putting the funds towards smaller, higher quality components with established working relationships...
wouldnt even know where to begin with amps either. definitely out of my depth!
Say they became double 12 + horns, that would leave me four more 12s. Could I try them as two more doubles with the horns from the Turbosound and Martin cabs?
that would neatly leave me the 15s for a bass bin.
would you consider the possibe results worthy of purchasing a DSP such as the one you mention?
the thought of spending any significant amount of money hurts a bit (at the moment at least) but by the sounds of it the other major weak link is the crossovers, but without an active to test them out it would be hard to know what passive setup to go for which does start to get me thinking I might be better off selling up and putting the funds towards smaller, higher quality components with established working relationships...
wouldnt even know where to begin with amps either. definitely out of my depth!
Well here is the thing, Community was known for making quality products so you will find good quality drivers here, the speakers were just designed before we had all this fabulously capable and cheap DSP processing at out fingertips. I'm guessing you have at least one stereo amplifier on hand? To do testing you really don't need much power so even a 20w home amplifier will do, then you just need an active crossover. You could pickup an older analog active crossover like the old Rane AC22/23 series, but the real magic happens when you add parametric EQ and time alignment, then you can really start to turn a lump of coal into a diamond. So bottom line is yes I think you could make these things sound much better, you don't need to run out and spend a pile of money on new gear just yet but if you are successful with the rebuild and want to put these things to use I would highly recommend the DSP processor mentioned above or if you buy new PA amplifiers chose those with built-in DSP like the Behringer iNuke DSP models. These boxes would definitely be capable of producing a lot of SPL with not a lot of watts too.. at least not by modern PA standards.. 250w per cab would be rockin loud.
In the interm look for products that are free or low cost to get you going, Parts Express has test micophones for little money and the free software package called Room EQ Wizard is a great tool for measuring loudspeakers, there is a lot to learn on that front alone but it's amazingly helpful to be able to see the effects EQ, crossover, phase and time alignment changes have on the sonic output of the speaker system.
In the interm look for products that are free or low cost to get you going, Parts Express has test micophones for little money and the free software package called Room EQ Wizard is a great tool for measuring loudspeakers, there is a lot to learn on that front alone but it's amazingly helpful to be able to see the effects EQ, crossover, phase and time alignment changes have on the sonic output of the speaker system.
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Now you put it like that, im starting to see this could be a good entry-level project to gain a better understanding of all the parts, and maybe get a half decent PA out of it too.
I will have a hunt around for a slightly more wallet friendly active crossover to play with, and see what I can find. I do have amps, although i might invest in a dedicated power amp.
Thank you very much!
I will have a hunt around for a slightly more wallet friendly active crossover to play with, and see what I can find. I do have amps, although i might invest in a dedicated power amp.
Thank you very much!
I realise I need a 101 in active crossovers. My understanding of certain things like sound processing is OK, as ive done some sound engineering and music production, but after an hour or so reading many articles not quite explaining what I need to know, I have fried my brain.
I get that they go between source and amplification. Lets say ive made a pair of double 12 + horns
With an active crossover with 6 outputs, such as the DCX2496, do you then use an output for each driver? doesnt that neccesitate an amp for each driver, or at least each pair at the same frequency. And then, in my mind, that means you have to wire at least three amps to two drivers each, one in each cabinet. Thats a lot of wires on the dancefloor. Or six amps, and then its all bi-amped, but that seems like overkill.
can someone just lay it out simply for me?
I get that they go between source and amplification. Lets say ive made a pair of double 12 + horns
With an active crossover with 6 outputs, such as the DCX2496, do you then use an output for each driver? doesnt that neccesitate an amp for each driver, or at least each pair at the same frequency. And then, in my mind, that means you have to wire at least three amps to two drivers each, one in each cabinet. Thats a lot of wires on the dancefloor. Or six amps, and then its all bi-amped, but that seems like overkill.
can someone just lay it out simply for me?
In this case bi-amping your dual 12s would require 4 amp channels, the 12s would be wired in parallel and get the same signal and the horn is on another channel. And there are 4 conductor speakers cables so it won't look any different or be any more complicated to hook up. Subs would be the same, if you have a pair of dual 15"s they each get a single channel of another amp so in total there are 3 amplifiers or 1 more than if the tops were passive. The benefit of this method is that you have more control over everything so you can get better performance and clearer sound, you can get close to this performance with a passive crossover but you have to build one of much higher complexity than a basic textbook crossover which takes a much more advanced understanding of speaker design. That is the end goal anyway, but even if you don't take it all the way this project can be a good learning experience.
Rebuild them as they are but tri-amp with a modern DSP.
They have the M200 midrange driver which is 110dB/1W, you will probably need all 4 of the 12's to keep up with it.
That driver is good down to 400Hz on a large horn so you could reasonably cross it over at 500 to 600 on the horn you have.
It isn't very smooth over 3.5k so you will want to cross over to a real tweeter-range horn & driver. The piezo element type tweeter Community used was never that great so look into a modern 1" with horn (there's some decent ones on Parts Express website)
If you want to go with a whole new format of a box, look at the configuration of the Mackie Fusion 3000 box (by RCF) -now discontinued, but it had 4 12's, a midrange horn and a tweeter horn and had a more conventional trap-box shape that you could build a similar size with the components you have.
The M200 has a 2" throat so any large 2" horn flare will mate with it.
They have the M200 midrange driver which is 110dB/1W, you will probably need all 4 of the 12's to keep up with it.
That driver is good down to 400Hz on a large horn so you could reasonably cross it over at 500 to 600 on the horn you have.
It isn't very smooth over 3.5k so you will want to cross over to a real tweeter-range horn & driver. The piezo element type tweeter Community used was never that great so look into a modern 1" with horn (there's some decent ones on Parts Express website)
If you want to go with a whole new format of a box, look at the configuration of the Mackie Fusion 3000 box (by RCF) -now discontinued, but it had 4 12's, a midrange horn and a tweeter horn and had a more conventional trap-box shape that you could build a similar size with the components you have.
The M200 has a 2" throat so any large 2" horn flare will mate with it.
That all sounds great...
Do you think there would any great sonic advantage to the mackie layout? They look good, and might be a better shape to deal with, smaller footprint for storage, but I probably wouldnt go to the trouble if it wasnt going to make them sound noticeably better.
As for amps, any recommendations? I suppose each channel has different requirements?
Also just so I am clear, you mean to replace the horn on the M200 to a larger one would be a good idea, and to replace the piezos completely?
Apologies for the barrage of questions, but I think this might be a good route to try out so it all wisdom is appreciated.
Do you think there would any great sonic advantage to the mackie layout? They look good, and might be a better shape to deal with, smaller footprint for storage, but I probably wouldnt go to the trouble if it wasnt going to make them sound noticeably better.
As for amps, any recommendations? I suppose each channel has different requirements?
Also just so I am clear, you mean to replace the horn on the M200 to a larger one would be a good idea, and to replace the piezos completely?
Apologies for the barrage of questions, but I think this might be a good route to try out so it all wisdom is appreciated.
CSX70 sounds a bit rough but kicks serious ***!!
If you seriously consider rebuilding these cabs, start by just building a new box, and putting the stock parts in it (including crossover). If you decide to do a similar layout to mackie fussion 3000, you should consider making it PPSL = push pull slot loaded, to reduce distortion and get the drivers closer to each other. This is important because of the high crossover frequency (700Hz).
If you seriously consider rebuilding these cabs, start by just building a new box, and putting the stock parts in it (including crossover). If you decide to do a similar layout to mackie fussion 3000, you should consider making it PPSL = push pull slot loaded, to reduce distortion and get the drivers closer to each other. This is important because of the high crossover frequency (700Hz).
I'd advise against butchering any of the stuff you have, since it all is in working condition.
New cabs for the csx70s are a good idea though, building to a more vertical form factor instead of the awkward original shape.
Then build some subs to stack the csx on. Two single 18" Reflex or tapped horns per side. You should be able to cross over quite low (80-100 Hzish).
New cabs for the csx70s are a good idea though, building to a more vertical form factor instead of the awkward original shape.
Then build some subs to stack the csx on. Two single 18" Reflex or tapped horns per side. You should be able to cross over quite low (80-100 Hzish).
Thanks bob, sounds good as well, if I can implement all these things sounds like I might end up with a decent system.
Done some googling, and PPSL sounds intriguing, but as a layman it also looks like I'll need a degree in acoustic engineering to work out a PPSL cabinet design... I saw one djk post mention a 4x12 PPSL design but i cant find it any more. Would you have any pointers for a place to start?
Done some googling, and PPSL sounds intriguing, but as a layman it also looks like I'll need a degree in acoustic engineering to work out a PPSL cabinet design... I saw one djk post mention a 4x12 PPSL design but i cant find it any more. Would you have any pointers for a place to start?
its less complicated than you think. You dont have to actually design from the ground up. The main goal is to keep the internal cabinet volume and tuning frequency the same, while changing the shape of the box.
PPSL is really just a twin driver reflex box with a specific physical arrangement. The dimensions of the 12inch lowmid drivers determine the size of the slot. You want to make the plenum (chamber inside the slot that contains the drivers) as narrow and shallow as possible. You have to keep in mind that the volume of the plenum has to be subtracted from the cabinets internal volume in the design process.
Wish I had more time to help you with the design.....
much obliged
I did some quick napkin calculations concerning the internal volume. The factory cab is about 260 litres external (calculated from dimensions), 221 litres internal (info on datasheet). The 40 litres difference is the volume taken up by the enclosure (including bracing), loudspeakers and fittings. To allow for PPSL mounting in a plenum while maintaining internal volume, you will have to increase the cabinet size a bit.
The plenum size will depend on slot width, but lets assume a 6 inch slot, 12 inches deep and 24 inches high. That would add up to roughly 27 litres. Taking the factory cab external dimensions, a total external volume of 287 litres would be required to accomodate the plenum and keep the internal volume (which is important for the reflex tuning).
If you reshape this to 1,2 m high, 0,5 m wide and 0,5 m deep, you end up at 300 litres. If you take that as a starting point, you can think about where to shave off a few cm/inches.
Its going to be a big, heavy box regardless, but a lot better to stack, and the PPSL loading might improve the sound as well by a) reducing distortion b) bringing drivers closer together, and thus improving summing between the woofers and mid driver. If you look at the datasheet, there are two nasty dips in the frequency response around the crossover frequency, 700 Hz.
I did some quick napkin calculations concerning the internal volume. The factory cab is about 260 litres external (calculated from dimensions), 221 litres internal (info on datasheet). The 40 litres difference is the volume taken up by the enclosure (including bracing), loudspeakers and fittings. To allow for PPSL mounting in a plenum while maintaining internal volume, you will have to increase the cabinet size a bit.
The plenum size will depend on slot width, but lets assume a 6 inch slot, 12 inches deep and 24 inches high. That would add up to roughly 27 litres. Taking the factory cab external dimensions, a total external volume of 287 litres would be required to accomodate the plenum and keep the internal volume (which is important for the reflex tuning).
If you reshape this to 1,2 m high, 0,5 m wide and 0,5 m deep, you end up at 300 litres. If you take that as a starting point, you can think about where to shave off a few cm/inches.
Its going to be a big, heavy box regardless, but a lot better to stack, and the PPSL loading might improve the sound as well by a) reducing distortion b) bringing drivers closer together, and thus improving summing between the woofers and mid driver. If you look at the datasheet, there are two nasty dips in the frequency response around the crossover frequency, 700 Hz.
Sorry to revive this thread but i have some time coming up and some spare money which is rare so I think im going to give these a go. so, one more round of questions!
to clarify, im going to rebuild the cabinets with the same internal volume as before, but adjusting for the extra volume of the plenum (the slot).
whats the difference between the plenum and the slot? and i suppose slot width is dictated by the depth of the drivers, as one magnetic structure will be in the slot, but i remember reading that closer is better.
does the volume of the slot matter?
is one driver in each pair is wired out of phase?
also, seeing as I will be using four 12s per box, i assume it is ok to have a single plenum for both pairs, two above two?
and lastly, does it matter how and where I mount the remaining compression and horn drivers?
i think with these questions even vaguely answered I can get drawing! thanks for all your help!
to clarify, im going to rebuild the cabinets with the same internal volume as before, but adjusting for the extra volume of the plenum (the slot).
whats the difference between the plenum and the slot? and i suppose slot width is dictated by the depth of the drivers, as one magnetic structure will be in the slot, but i remember reading that closer is better.
does the volume of the slot matter?
is one driver in each pair is wired out of phase?
also, seeing as I will be using four 12s per box, i assume it is ok to have a single plenum for both pairs, two above two?
and lastly, does it matter how and where I mount the remaining compression and horn drivers?
i think with these questions even vaguely answered I can get drawing! thanks for all your help!
just so you can see if im on the right tracks...
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An externally hosted image should be here but it was not working when we last tested it.
Hi Dokkodo,
nice to see you're going ahead with this project! Sorry for the delayed response.
both correct. Measure the depth of the woofer from back of magnet to front of gasket. Assuming you want to avoid additional access panels on the sides, you would want to make the slot just wide enough that you can insert the drivers. Remember to take the rim/gasket of the non-inverted driver into account, or countersink the driver so that it doesn't stick out.
only in the sense that if you want to replicate the original box volume and tuning, you have to account for it. You could for example cut the back corners of the plenum to reduce volume. If your carpentering skills are up to the task, you could make the plenum trapezoidal (narrower at the back, wider in the front). That way mounting might be a bit easier, and you could get the drivers closer to each other than with a rectangular footprint plenum. But that would be a lot more work, and you would probably have to build a mockup to get it perfectly right.
correct, the inverted drivers need to be wired out of phase
yes, should be ok. someone has done a 4x12" sub with single plenum
I suppose i would make most sense to mount the horn directly above the slot.
good luck with your build! And please report whatever you come up with, I'm highly interested My partner in crime just bought a second pair of csx60's, and I'm itching to eventually do something similar to what you are attempting
did you check this thread?
http://www.diyaudio.com/forums/subwoofers/177905-thread-those-interested-ppsl-enclosures.html
nice to see you're going ahead with this project! Sorry for the delayed response.
the way I see it (I might be wrong!): the plenum is the volume that contains the drivers, enclosed beyond the slot. The slot is the opening in the front baffle that couples the airmass around the drivers to the surroundings
both correct. Measure the depth of the woofer from back of magnet to front of gasket. Assuming you want to avoid additional access panels on the sides, you would want to make the slot just wide enough that you can insert the drivers. Remember to take the rim/gasket of the non-inverted driver into account, or countersink the driver so that it doesn't stick out.
only in the sense that if you want to replicate the original box volume and tuning, you have to account for it. You could for example cut the back corners of the plenum to reduce volume. If your carpentering skills are up to the task, you could make the plenum trapezoidal (narrower at the back, wider in the front). That way mounting might be a bit easier, and you could get the drivers closer to each other than with a rectangular footprint plenum. But that would be a lot more work, and you would probably have to build a mockup to get it perfectly right.
correct, the inverted drivers need to be wired out of phase
yes, should be ok. someone has done a 4x12" sub with single plenum
I suppose i would make most sense to mount the horn directly above the slot.
good luck with your build! And please report whatever you come up with, I'm highly interested
My partner in crime just bought a second pair of csx60's, and I'm itching to eventually do something similar to what you are attempting did you check this thread?
http://www.diyaudio.com/forums/subwoofers/177905-thread-those-interested-ppsl-enclosures.html
Amazing, no worries for the delay im just grateful for the advice. I will definitely report back!
im going to have to read that thread and your definitions a few more times just to get it clear in my head!
i have found that thread before and have read bits of it, theres a lot to absorb and as I said, a lot of technical talk that melts my brain, but useful info to chew through
I am a carpenter by trade luckily so I have a technical mind and a workshop, but audio engineering is a whole world for which I need a new dictionary.
I quite like the idea of trapezoidal because there is something quite strange looking about a rectangular speaker cab with a rectangular cavity in the middle! Might give this a go http://www.diyaudio.com/forums/attachments/subwoofers/224619d1306468315-thread-those-interested-ppsl-enclosures-plenums_angled_back_2.pdf
In fact, I dont see why you couldnt get the drivers basically touching, i suppose you want to leave room for cone travel but if you mount them into the panels and then build the panels in you could get them very close indeed.
This
seems to suggest a port, but I have also read that sealed is fine too, and i guess the original boxes were sealed so Ill stick to that. I guess it would make sense to tweak the tuning of the box etc but as I am an amateur ill leave that for now!
im going to have to read that thread and your definitions a few more times just to get it clear in my head!
i have found that thread before and have read bits of it, theres a lot to absorb and as I said, a lot of technical talk that melts my brain, but useful info to chew through
I am a carpenter by trade luckily so I have a technical mind and a workshop, but audio engineering is a whole world for which I need a new dictionary.
I quite like the idea of trapezoidal because there is something quite strange looking about a rectangular speaker cab with a rectangular cavity in the middle! Might give this a go http://www.diyaudio.com/forums/attachments/subwoofers/224619d1306468315-thread-those-interested-ppsl-enclosures-plenums_angled_back_2.pdf
In fact, I dont see why you couldnt get the drivers basically touching, i suppose you want to leave room for cone travel but if you mount them into the panels and then build the panels in you could get them very close indeed.
This
seems to suggest a port, but I have also read that sealed is fine too, and i guess the original boxes were sealed so Ill stick to that. I guess it would make sense to tweak the tuning of the box etc but as I am an amateur ill leave that for now!
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