Subwoofer experts. . .

[MrBoat]

As I have posted in the DIY section about plans to build (kit should be here in a few days) Jeff Bagby's Continuum bookshelf speakers, I was reading that he designed a subwoofer for them that works in a small sealed enclosure. The problem being, the TC Sounds Epic12 driver is no longer available, and TCSounds has gone by the wayside as well. Is it simply a matter of choosing a driver that works similarly in a small box? Is it that important? I also have the 12" Ultimax in a sealed (2 cu. ft.) box hooked up to an NU3000dsp amp. I also own a Dayton RS315HF-4 12" driver that is NIB. I could not find on google where he has chosen an alternate driver for the Continuum sub.

I guess part of his using the small box is to be a practical match with the small bookshelf speakers. It would be cool if I had the option to make a similarly scaled subwoofer for a near field arrangement for these speakers if I choose.

I'm sure I could google this to some point of cross-reference, or even perhaps email Jeff Bagby about it but I would like to get some ideas from you folks as well. I have tried to sign up multiple times to the PE forum but they never have replied. Perhaps they have seen all the jibberish I have posted here and don't want to open this can of worms there.

 

[shadyJ]

All you need is a good subwoofer driver, it doesn't have to be a particular type. The TC Sounds driver absolutely is not somehow a match for the Continuum speakers. It is just a reasonably good driver that can work in a small enclosure. Are you absolutely restricted to a small enclosure? Just look at some drivers, plug in some values into WinISD, and see what will work in your target enclosure. A Dayton Reference HF driver will work fine with the Continuums. If it were me, I would get two drivers for two enclosures, and run them off a two channel amp, especially for near-field use where localization tends to be more pronounced. Hell, get four of the Dayton Ref HF 8 ohm drivers, they can be used at two per channel because of their easy load.

 

[MrBoat]

All you need is a good subwoofer driver, it doesn't have to be a particular type. The TC Sounds driver absolutely is not somehow a match for the Continuum speakers. It is just a reasonably good driver that can work in a small enclosure. Are you absolutely restricted to a small enclosure? Just look at some drivers, plug in some values into WinISD, and see what will work in your target enclosure. A Dayton Reference HF driver will work fine with the Continuums. If it were me, I would get two drivers for two enclosures, and run them off a two channel amp, especially for near-field use where localization tends to be more pronounced. Hell, get four of the Dayton Ref HF 8 ohm drivers, they can be used at two per channel because of their easy load.

I've been looking a little harder with some different search terms and am beginning to find some different takes on this setup, like here in the first photo. Talk about raising the bar. That's a tidy little match, if you ask me.

I already do have a good 12" that I am using so I can at least try the speakers with a sub and with DSP. Just looking at options. I know you folks know a lot about these drivers and such and haven't steered me wrong yet so. . . .

 

[TheWarrior]

You might try a SEAS L26ROY with MiniDSP 250W amp.

I'm using a slightly different version of that woofer, first as an open baffle (literally copied the Linkwitz Orion, and made it a subwoofer) and now as a dual sealed. Currently, I have scrambled the brains of the minidsp plate amp by using both PC and Mac to program it so I cannot provide any measurements till I get it working again. But I will be purchasing the above linked woofer when I have time to build more subs. It has a lower Fs making it better suited for movies' LFE.

Programming the DSP takes some time, but patience is well rewarded. You can tune that sub to sound good in any room!*

*recommended reading: 'Sound Reproduction: Loudspeakers and Rooms' by Floyd E. Toole

 

[MrBoat]

Initially this was because Jeff Bagby thought to make a subwoofer 'for' the Continuum speakers. I thought perhaps it was a bit more critical the selection. I see now where a lot of it had to do with scale with the aesthetics as well. I see that Paul Carmody has designed some different boxes for the RSS210 driver that would probably work as well also.

My Tempests and the Ultimax already take up all the room I have here, and they are not going anywhere so it's not like I even have room in here for another subwoofer or another pair of speakers without turning this into a speaker display room. Not that there is really anything wrong with that.

 

[Pogre]

I've been looking a little harder with some different search terms and am beginning to find some different takes on this setup, like here in the first photo.

Those look sharp! I love the way the ports are finished to match the cabinet. If I had the patience and skills with finishing I'd really like to tackle a DIY project. The pics in that thread are impressive.

 

[MrBoat]

Those look sharp! I love the way the ports are finished to match the cabinet. If I had the patience and skills with finishing I'd really like to tackle a DIY project. The pics in that thread are impressive.

Indeed. He did a nice job on that. I would have to listen to them first to see if they deserved such a treatment.

 

[Verdinut]

All you need is a good subwoofer driver, it doesn't have to be a particular type. The TC Sounds driver absolutely is not somehow a match for the Continuum speakers. It is just a reasonably good driver that can work in a small enclosure. Are you absolutely restricted to a small enclosure? Just look at some drivers, plug in some values into WinISD, and see what will work in your target enclosure. A Dayton Reference HF driver will work fine with the Continuums. If it were me, I would get two drivers for two enclosures, and run them off a two channel amp, especially for near-field use where localization tends to be more pronounced. Hell, get four of the Dayton Ref HF 8 ohm drivers, they can be used at two per channel because of their easy load.

If Mr Boat wants to save on cabinet volume, why not use two RSS315Hf-8A subs in a Push-Pull Isobaric configuration and he could save about 40% in cabinet volume taking into account that the smaller box would probably need more bracing with two drivers in that smaller space.
For such a design, I would suggest a net box volume of 2.5 cubic feet for a better low frequency performance.

 

[shadyJ]

If Mr Boat wants to save on cabinet volume, why not use two RSS315Hf-8A subs in a Push-Pull Isobaric configuration and he could save about 40% in cabinet volume taking into account that the smaller box would probably need more bracing with two drivers in that smaller space.
For such a design, I would suggest a net box volume of 2.5 cubic feet.

That type of configuration gives up an awful lot of output for some reduction in distortion. I think it would be much better just to have the drivers in a normal sealed or ported box. Those drivers are already theoretically low distortion to begin with, but they are not really high displacement drivers, so that solution would be helping them in an area that they don't need any help with at the expense of an area that they shouldn't have any obstruction with. I think it would be neat, but in an no-expenses spared system where cost is not really an object.

 

[speakerman39]

That type of configuration gives up an awful lot of output for some reduction in distortion. I think it would be much better just to have the drivers in a normal sealed or ported box. Those drivers are already theoretically low distortion to begin with, but they are not really high displacement drivers, so that solution would be helping them in an area that they don't need any help with at the expense of an area that they shouldn't have any obstruction with. I think it would be neat, but in an no-expenses spared system where cost is not really an object.

Why not add a PR or two? If excursion is or can be an issue it is my understanding that PR is an easy way to fix that, no? At least, that is how I understand one of the best uses for a PR.


Cheers,

Phil

 

[Verdinut]

That type of configuration gives up an awful lot of output for some reduction in distortion. I think it would be much better just to have the drivers in a normal sealed or ported box. Those drivers are already theoretically low distortion to begin with, but they are not really high displacement drivers, so that solution would be helping them in an area that they don't need any help with at the expense of an area that they shouldn't have any obstruction with. I think it would be neat, but in an no-expenses spared system where cost is not really an object.

As a matter of fact, I used the previous RSS315HF sub in a pair of cabinets in a 3-way system with success. It really is musical and has a very smooth response in a 3.25 cf BR cabinet.

 

[shadyJ]

Why not add a PR or two? If excursion is or can be an issue it is my understanding that PR is an easy way to fix that, no? At least, that is how I understand one of the best uses for a PR.


Cheers,

Phil

Passive radiators basically act like ports. Its a way to get port-like behavior from a smaller enclosure. It does alleviate excursion in the same sense that ports do. If space is not a concern, just making a ported enclosure is simpler and less expensive,

 

[shadyJ]

As a matter of fact, I used the previous RSS315HF sub in a pair of cabinets in a 3-way system with success. It really is musical and has a very smooth response in a 3.25 cf BR cabinet.

I don't doubt that. They have very low Le which should help make for a extended HF response for a subwoofer driver. They should be relatively easy to put in a full-range 3-way speaker.

 

[MrBoat]

I'm not hurting for bass. I just thought Bagby had some magic reason for choosing that combination. I currently have the 12" ultimax in a 2 cu ft. sealed, hooked up to a inuke 3000dsp. It's has a wide range of behavior options available with that amp, I am finding, as I poke around the settings. My room also has a lot of gain, which is why I am getting away with using only a 12" driver. It can actually get quite ridiculous in here and as it is, I am at about -6db on the gain setting.

So far, the best setting combined with the Tempests seems to be about 1.5 x the lowest rating of those, which is about 38hz, IIRC, which has me running the sub cut off at about 50-55hz since the sub has to be placed relatively close to the main speakers. The Tempests have such a good sounding mid bass down into the 40's it's a shame not to exploit it. I have tried all the other suggested typical crossover points, mains large/small etc.

I also have a RSS315HF-4 that I can try for a different flavor. I just don't have a lot of placement options. As it stands, I can rattle the interior doors in here if I really liked a lot of bass, but this seems to be the most natural sounding, and things like bass guitars sound live, like they are hooked up to a bass amp in my living room.