[TomS]

I'd like to differentiate between my commercial four-sub system, which I call the "Swarm", and a fullbore Geddes system; the former is simpler and the latter more advanced. 

My system uses a single central amplifier to drive four small subs.  The four small subs have an inherent rolloff that is approximately the inverse of anticipated room gain.  The single central amplifier has a 4th order lowpass filter to aggressively roll off the top end of the subs.   I suggest a few rules of thumb for placement, fiddling with levels and crossover frequency and (if necessary) using the single band of parametric EQ in my amplifier.

If I understand correctly, Earl uses three or four subs which each have their own amplifier, and he takes advantage of that to optimize each sub individually for level, low-pass frequency, and phase.  He is also using mains that are very low-Q sealed box systems, so he uses a different protocol for getting a good blend with his mains.

Duke,

Yes, that is exactly what he's doing so thanks for chiming in 

I wanted others to understand that the "Swarm" was a very specific intentional design using the method you developed and described above, not just 4 mutt or random subs thrown together. It indeed works very well, having heard it myself a couple of times, and is a bargain in terms of the high performance bass you can achieve with it in minimal floor space.

Tom

[rascal]

There is also $100 shipped Polk audio sub here

Rclark- my recommendation is to first measure your set-up, and then figure out where you need to augment the bass. The toughest part is to get the measurements going- for low frequencies Radio Shack SPL meter does the job.

[Letitroll98]

Thanks for bringing it back to Cheap and Cheerful rascal.  From my memory of it, Geddes says you don't need expensive subs to make his system work, and he used three modest LF cutoff subs and one real sub.  Thus you could use three of the 8" "subs" (I'd call them woofers, not sub-woofers) and one of the 12" for a C&C distributed sub system.  They all have their own amps and you simply need a divider, help me out here I think it's Behringer that makes one?     

[doug s.]

Thanks for bringing it back to Cheap and Cheerful rascal.  From my memory of it, Geddes says you don't need expensive subs to make his system work, and he used three modest LF cutoff subs and one real sub.  Thus you could use three of the 8" "subs" (I'd call them woofers, not sub-woofers) and one of the 12" for a C&C distributed sub system.  They all have their own amps and you simply need a divider, help me out here I think it's Behringer that makes one?   

geddes also says you need min 10" - ie: subs, not "woofers"...   

doug s.

[Rclark]

Does it really matter the size of the sub, really? I mean what if you used very high quality 8's with big motors?

It has to be more about the band of freqencies played, rather than the size of the woofer cone, huh? 8's are subwoofers too! Maybe not in this case, but last time I checked, they make subwoofers with 8" drivers. If we're talking music, not movies, and 30hz is about what you need for that, what's wrong with 8" subs? Especially in a small room? And why wouldn't an 8" swarm work in a small room? Why does it have to be tens?

 BUT.. those Polk 10" look like they could be good, they have phase control... $99. However, I believe the 12" Monoprice sub coming in Jan has all those things, phase, crossover, and 150 watts to boot.

[Rclark]

 I'm really enamored now with the idea JohnR mentioned of making my Brahma's into an OB subwoofer. But I think he's busy because he hasn't answered my PM. We have a tablesaw in the house now and I think I could get some MDF and make my own... Is there a sort of calculator I could use to build this sub? Enter the TS and then it spits out the OB H-frame (or whatever) plans I need? I would really love to make this happen. I think he said I need an amp with an EQ as well.

[doug s.]

Does it really matter the size of the sub, really? I mean what if you used very high quality 8's with big motors?

It has to be more about the band of freqencies played, rather than the size of the woofer cone, huh? 8's are subwoofers too! Maybe not in this case, but last time I checked, they make subwoofers with 8" drivers. If we're talking music, not movies, and 30hz is about what you need for that, what's wrong with 8" subs? Especially in a small room? And why wouldn't an 8" swarm work in a small room? Why does it have to be tens?

 BUT.. those Polk 10" look like they could be good, they have phase control... $99. However, I believe the 12" Monoprice sub coming in Jan has all those things, phase, crossover, and 150 watts to boot.

for me, even for music, subs need to be flat to 20hz.  i am sure you can do it w/8' drivers - how much money ya got?     whatever it is you come up w/it won't be "cheep & cheerful".  well, i take that back, it may wery well be cheerful, but not cheap!   

when i first went w/outboard subs, my mains at the time were -2db at 20hz.  going w/a pair of real subs was a huge improvement - extended dynamics, decreased distortion, better soundstaging, better performance from the mains as they and their amps were now crossed over at 70hz and say no low frequencies.  and i don't to tv or ht...

doug s.

[Rclark]

 I have to admit to you Doug, I've not spent much time at 20hz, I'm probably missing out  . Hopefully someone can help me with the apparently complicated task of making these Brahma's OB subs. I think now I would rather do that if possible, because I assume they would sound much better than 4 cheap subs in a swarm because I listen near field, pretty much. If it is indeed possible to get those working well, then I will have saved a ton of money for the time being and will likely have a pretty wicked little system.

[doug s.]

I have to admit to you Doug, I've not spent much time at 20hz, I'm probably missing out  . Hopefully someone can help me with the apparently complicated task of making these Brahma's OB subs. I think now I would rather do that if possible, because I assume they would sound much better than 4 cheap subs in a swarm because I listen near field, pretty much.

save your money for when you can afford another pair of subs w/drivers even better than the brahmas - then do your swarm!   

doug s.

[Rclark]

 
 yeah, I've spent a good bit here already, and I've got that Maggie mod coming up here in a little over a month, which is gonna be costly.. I'll have a $2500 pair of MMG's (omg) with all that tally'd up.

 If I can get the Brahma's working for the time being as OB's, I think I would be in heaven, and could probably run them for some time to come.
 
 I'll then do a Swarm in my living room for the tv.

[persisting1]

I'll have a $2500 pair of MMG's (omg) with all that tally'd up.

Wow, you could have bought a used pair of 3.6Rs 

[Rclark]

Well, not quite that much, but yeah, about that much. I know, but I've spoken to lots of people with these things and they swear by them. Up and down and all day long. And they look awesome, the finished product, very nice looking.

And 3.6r's would overwhelm my room, physically and sonically. The MMG's are already pushing it. I love them, but they have their space requirements to sound good, and there's no getting around the fact they dominate the room's dimensions because of that. I know that for me, even eventually placing them in a larger space, they would play loud enough. One of the benefits of the mod is an increase in efficiency from around 87 dB to 92dB.

[JohnR]

Hopefully someone can help me with the apparently complicated task of making these Brahma's OB subs.

It's not complicated. Except that you will need measurements and EQ to get the best results. But that applies to pretty much all types of bass system, really...

If you'd care to start a thread in the OB circle then I and others can advise. A thread about C&C swarm isn't really the best place (nor is PM, sorry no offence but I prefer to discuss on the open board). However, to get good results you'll need to be able to measure. There are two reasons why you need to measure. One is to figure out where to put the sub (any sub) to get the best response. The other is so you can adjust EQ.

To illustrate the first point, here are a couple of examples showing how positioning affects subs in my room. First, a dipole sub (ignore the green line):



Next, a single sealed sub:



As you can see, it doesn't matter what type of sub you have, positioning it makes a lot of difference. While you can proceed without measurements, I personally wouldn't want to offer advice in that case, as it would be impossible to make any suggestions from afar.

As an aside, I heard a very nicely setup pair of MG3.6Rs last weekend. And they did sound very nice, with a DEQX for biamping the Maggies and a pair of sealed subs positioned in the room. Has me thinking about trying MMGs myself...

[Rclark]

OK, I'll post a new thread about them. THanks 


 Meanwhile, it's officially Halloween, and I'm gonna go crash with episode 3 of Walking Dead on Netflix. Holy cow is that a good show.

[persisting1]

@Rclark, sorry if I've missed it, but what upgrades have you done to them?  Yeah, the 3.6s wouldn't work in a small room. 

[Rclark]

Oh, im scheduled to get the Magnestand mod done some time in Dec.

http://www.indiespinzone.com/magnestand.html

[persisting1]

Oh, im scheduled to get the Magnestand mod done some time in Dec.

http://www.indiespinzone.com/magnestand.html

Those look really nice 

[Letitroll98]

And if you delay the multi-sub approach for a bit, he's a tweak that can achieve much of the same results, albeit only if you have one listening seat.  With the woofer pointed to the side, place your sub with the woofer center exactly, I mean exactly, within 1/4", of the distance to your main speakers from your listening seat (from the middle of the panel on your Maggies, right where it transitions from Quasi-ribbon to bass panel, be careful with the tape measure, don't puncture the membrane).  Turn any phase control to zero.  Make sure the sub is mounted rigidly, preferably on wooden blocks, maple is best, or spikes if you insist.  I'm not going to tell you what it will sound like, just try it and report back.   

[jtwrace]

And if you delay the multi-sub approach for a bit, he's a tweak that can achieve much of the same results, albeit only if you have one listening seat.  With the woofer pointed to the side, place your sub with the woofer center exactly, I mean exactly, within 1/4", of the distance to your main speakers from your listening seat.  Turn any phase control to zero.  Make sure the sub is mounted rigidly, preferably on wooden blocks, maple is best, or spikes if you insist.  I'm not going to tell you what it will sound like, just try it and report back.   

What do you mean delay?  As in ms delay?  How many subs?

[Letitroll98]

What do you mean delay?  As in ms delay?  How many subs?

He said he wasn't getting multiple subs until he modded the Maggies.  Not a ms time delay, although in the end, that's what we're talking about.  Even if he orders subs today or starts the DIY project, he can move the sub he has tonight.     This doesn't solve the problems when you have multiple seatings ,even a couch, that the multi-sub approach addresses, but the technique has a remarkable effect for one seat listening.

On a more general note, your system as example and doug s's comments about 20hz subs are of course the more optimal route to go, however please dear sirs, remember we are on the Cheap and Cheerful HiFi circle where compromises are the rule rather than the exception.  Your kind indulgence is most appreciated.