Suggestions for small dual opposed subs

[Alex2507]

My first thought on the matter was JL Audio 8W7 drivers but they're like $500 a piece. I would need four. That's a little rich for my blood. 10"drivers would be okay.

I just want the cabinet to not move on it's own without having to make it weigh 10,000 pounds and I'd like to not need a means of decoupling the cabinet from the building structure.

Sealed is preferred but passive radiators are okay too. I'm not sure if you can do dual opposed with a port.

I would need two subs for use in a living room/home theater setting. Since I'm a condo dweller, high SPL and low extension are NOT priorities. For me it's more about the music in movies than me and my neighbors hearing the LFE track plumbing the depths of hell. An F3 of 30Hz and maybe an F6 of 25 Hz would be cool.

Now that I'm thinking about this what I really want is something that sounds like the two subs that TLS previously gave me an alignment for. I've heard an Epic Empire at Rick's and a monster PSA dual opposed at Billy's. I like the concept.

 

[fuzz092888]

Dual opposed using the CSS SDX10. I have my single in ~1cuft if not less. Double up on the cab, throw two of those in there and then build another. I can vouch that the SDX10, while it won't plumb the depths, will provide plenty of clean bass above 20 or so hz. Four of them should be more than plenty for an apartment.

$680ish shipped for all 4 I think.

http://www.creativesound.ca/details.php?model=SDX10

 

[Alex2507]

I just spotted this:

http://www.avsforum.com/forum/253-plasma-panels/1771561-samsung-pn59-7000-series.html#post29252825

 

[TLS Guy]

I think we can do that to order. How does four drivers at $113 each sound? What is your max allowable box volume? Yes, you can port a dual opposed sub. Even with your modest spec, you will be adding a lot of Eq to the unit to meet your spec. 10" drivers sealed are going to have an F3 well north of 30 Hz without Eq.

To be honest, I have never been a great lover of sealed enclosures. They are brute force power hogs. The only thing to recommend them is a small box volume. After that it is all downside. Whichever way you look at it, an unaided loudspeaker cone is a lousy thing to power a space with at low frequencies.

 

[adk highlander]

When you meeting him? Merry Christmas.

 

[Alex2507]

When you meeting him? Merry Christmas.

Just swang this past the girl and had to say "profit margin" about 6 times in order to explain why Plasma was no longer being made. Then I had to use the term "picture quality" another 6 times in order to talk about something pertinent to "picture quality".

I think we can do that to order. How does four drivers at $113 each sound? What is your max allowable box volume? Yes, you can port a dual opposed sub. Even with your modest spec, you will be adding a lot of Eq to the unit to meet your spec. 10" drivers sealed are going to have an F3 well north of 30 Hz without Eq.

To be honest, I have never been a great lover of sealed enclosures. They are brute force power hogs. The only thing to recommend them is a small box volume. After that it is all downside. Whichever way you look at it, an unaided loudspeaker cone is a lousy thing to power a space with at low frequencies.

I can go 1' x 1.25' x 2' internal volume at the very most. Everything comes out of that; cone displacement, braces and port. I think I can see where this ought to end up: you talking me into a single driver ported design trading off unneeded SPL for always sought after lower frequencies but anyway, that's the space I have to work with.

What are the $113 drivers?

 

[TLS Guy]

Just swang this past the girl and had to say "profit margin" about 6 times in order to explain why Plasma was no longer being made. Then I had to use the term "picture quality" another 6 times in order to talk about something pertinent to "picture quality".



I can go 1' x 1.25' x 2' internal volume at the very most. Everything comes out of that; cone displacement, braces and port. I think I can see where this ought to end up: you talking me into a single driver ported design trading off unneeded SPL for always sought after lower frequencies but anyway, that's the space I have to work with.

What are the $113 drivers?

Be patient!

 

[Matt34]

Not dual opposed sealed sub but it's small, clean, good output, easy to power and it's available in flatpacks!! Everyone should experience one at least some point in their life.

http://www.diysoundgroup.com/ported-subwoofers-1/anarchy-th.html

http://www.avsforum.com/forum/155-diy-speakers-subs/1238398-reed-exodus-anarchy-25hz-tapped-horn.html

 

[Alex2507]

Be patient!

I waited almost an hour!

Not dual opposed sealed sub but it's small, clean, good output, easy to power and it's available in flatpacks!! Everyone should experience one at least some point in their life.

http://www.diysoundgroup.com/ported-subwoofers-1/anarchy-th.html

http://www.avsforum.com/forum/155-diy-speakers-subs/1238398-reed-exodus-anarchy-25hz-tapped-horn.html

I've got a couple of questions about those in case you happen to know.

1. Would having the port toward the top of the cabinet be okay?

2. Is any version of the Exodus or the Tang Band driver preferred?

3. I could have sworn there was a three.

Those dimensions of 20x30x8 would work along my back wall. The ports would face each other but I'm not crazy about the source/port being right on the floor. That's sort of the point of wanting dual opposed.

4. Oh yeah, I knew there was a three. What would you need to apply the 25Hz high pass filter?

Back to what I was saying. The dual opposed cabinet shouldn't need an isolation absorber to decouple it from the structure.

Now that I think about this, having previously given one of Dr. Mark's alignments an honest effort, I can't wait to try out what ever it is he cooks up.

Please Lord, let it be a plastic tube port. Oh puh-lease let it be a plastic tube port.

 

[Matt34]

1) I don't see why not. For a boost in output it's recommended to have the port facing into a wall corner.

2) The Exodus 6.5" has a touch more excursion than the Tang Bands W6-1139SI, otherwise very similiar.

3) http://www.parts-express.com/harrison-labs-fmod-inline-crossover-pair-30-hz-high-pass-rca--266-248 Will leave a little bit on the table.

 

[TLS Guy]

Be patient!

I have done five models for you.

I have modeled this new slime line 10" driver from Dayton Audio, in vented push pull alignment, in isobarik push pull vented alignment and in push pull sealed configuration. Note that for the isobarik enclosure you will need a total of 8 drivers for two subs.

I modeled this 10" Ultimax driver from Dayton Audio. I modeled it in sealed push pull configuration.

Lastly I modeled this 10" SDX 10 from Creative Sound solutions, in sealed push pull configuration.

This exercise confirms the power penalty of reduced enclosure size.

Now you have to look at these specs in relation to the final impedance. The isobarik and the SDX 10 are both 2 ohm. The others are four ohm. So for these designs you will need a 2 ohm capable amplifier.

The most effective sub is the LS10-44 vented. However it exceeds you volume criterion by 0.6 to 0.7 cubic feet when you take driver, port volume into into consideration.

The isobarik model has a performance almost identical to the standard version except the penalty of reduced enclosure size is a requirement for double the amp power for the same spl. It meets your size criterion, and I think would have a total internal volume of 2.2 cu.ft. You will have to be creative with the port however. I do isobariks mounting the drivers back to back and make the tunnel connecting them with circular wood or MDF spacers. Each driver in the tunnel is then wired out of phase with its partner so the cones move in the same direction. The the two pairs are obviously wired in phase so they push pull.

The sealed version of this driver does not have enough output and there is not enough driver excursion for Eq. I would not build that one.

The Ultimax and the the SDX 10 model virtually identically, except that the SDX 10 is 2 ohm. The enclosure size, spl and F3 are so close it makes not difference. The increased sensitivity is illusory as the amp power for the same spl will be the same because of the halving of the impedance.

Now the two viable sealed contenders and the two vented designs are all 12 db down at 20 HZ. At 30 HZ the sealed alignments are 7 db down compared the vented subs. However both sealed alignments will tolerate 6 db of boost at 30 HZ and may be a little more.

So you will need three times the amp power for the sealed alignments compared to the conventional vented, and twice the power compared to the isobarik vented.

Now when you build it, I would use threaded bars right though all drivers one side of the enclosure to the other. So either the two or four drives are strongly connected with the mounting rods. This is an old trick of Laurie Fincham when doing push pull.

If you build one of the vented try and see if you can make the port act as one of the braces. Fitting the port in the isobaric enclosure will take some ingenuity, but I believe it is possible.

Getting your mind round these models will likely keep you busy for a while. All except that one vented alignment with the slimline driver, I believe to be viable designs and meet your criteria for performance though one is a little large, although only the vented alignments will meet your criteria without Eq.





Both pay the same penalty of reduced enclosure size. The Ultimax has the slightly lower Q which I think might be enough to give it a slightly tighter but this may not be a significant difference.

 

[Alex2507]

Thanks, Mark. My goodness but those results suck and my brain is about to explode trying to figure out a way to work a vent into that space with the 4 Ohm LS10-4410. I don't have the kind of budget it would take for isobaric set ups and the 2 Ohm thing is tough.

Gonna sleep on this.

 

[TLS Guy]

Thanks, Mark. My goodness but those results suck and my brain is about to explode trying to figure out a way to work a vent into that space with the 4 Ohm LS10-4410. I don't have the kind of budget it would take for isobaric set ups and the 2 Ohm thing is tough.

Gonna sleep on this.

I think the short list is dual LS10-4410 if you don't mind the increase in size. The other option, and the cheapest is to use a single driver. From what you want to use this for, it would be fine.

About ports. The vent air velocity is predicated on you actually using the full specified power of the drivers. One of the nice things about DIY, is that you can design to actually what you are going to use it for. If you are not going to blast the things, then you won't be moving as much air and you don't need such a large vent. In any event, I think manufacturers really guild the lily on power specs. I would bet all of those drivers and pretty much all others would blow up if you drove them to spec. I don't believe for a minute you could drive any of those units at their published continuous power specs.

So if you thought you would never power each sub with more than 200 watts, which is likely, you can use a 4" diameter tube vent 17" long flared at both ends. If I were using it in your living situation that is what I would do. So a 200 watt per channel X2 will be just fine.

So with a drive of 200 watts you get 110 db instead of 113 db at 30 Hz. If you lowered the drive to 100 watts you would still get 107 db from each sub. Under the conditions of use you describe, I really doubt you would drive them that hard.

With that vent this design meets your size criterion within at least .2 cu. ft anyway. The vent volume is only 0.12 cu.ft. The drivers are very low volume displacement.

That is you most cost effective performance ratio for what you are trying to do. It is also the simplest.

Your other option is the Ultimax build.

If you want to go with a single driver let me know and I will remodel.

 

[Alex2507]

I think the short list is dual LS10-4410 if you don't mind the increase in size. The other option, and the cheapest is to use a single driver. From what you want to use this for, it would be fine.

I have been running back and forth to the back of my couch with a tape measure like a rodent on a tread mill. My g/f just keeps saying, "no". I tried telling her who you are. She said, "no".

I already have similarly sized single driver subs in those positions on top of some Auralex Grammas. This exercise is about having a dual opposed (push pull) configuration exceed the absorbers ability to NOT energize the structure and to of course out perform my current Infinity PS10 subs in SQ if not extension and amplitude.

About ports. The vent air velocity is predicated on you actually using the full specified power of the drivers. One of the nice things about DIY, is that you can design to actually what you are going to use it for. If you are not going to blast the things, then you won't be moving as much air and you don't need such a large vent. In any event, I think manufacturers really guild the lily on power specs. I would bet all of those drivers and pretty much all others would blow up if you drove them to spec. I don't believe for a minute you could drive any of those units at their published continuous power specs.

So if you thought you would never power each sub with more than 200 watts, which is likely, you can use a 4" diameter tube vent 17" long flared at both ends. If I were using it in your living situation that is what I would do. So a 200 watt per channel X2 will be just fine.

So with a drive of 200 watts you get 110 db instead of 113 db at 30 Hz. If you lowered the drive to 100 watts you would still get 107 db from each sub. Under the conditions of use you describe, I really doubt you would drive them that hard.

As it turns out I have a couple of Marantz MA700 amps (300 watts @ 4 Ohms). Just to clarify 'each sub' consists of 2 of those drivers. I also have a 7 channel amp that I could reintroduce into the system. I could use one channel per subwoofer driver and still have the remaining 3 channels for the center and mains.

You are right, though. I'll never drive anything very hard. Amplification isn't a concern at the moment. I find the tube vent option very appealing.

With that vent this design meets your size criterion within at least .2 cu. ft anyway. The vent volume is only 0.12 cu.ft. The drivers are very low volume displacement.

That is you most cost effective performance ratio for what you are trying to do. It is also the simplest.

Your other option is the Ultimax build.

If you want to go with a single driver let me know and I will remodel.

I'm not building anything with an F3 of 50Hz or even worse, 65 Hz. I very much like the idea of my rec'r xo putting out an LFE signal that I amp up and listen to period. While I'm not too stupid to own gear, there is some gear that I'm not smart enough to use. Gotta factor in some intellectual laziness and the fact that I don't want to mess with EQ's if I don't have to

I was using the term 'dual opposed' and I see you use the term 'push-pull'. I saw an image for 'push pull' that certainly didn't look like what I wanted. Just to be clear: I want drivers on opposite ends of the enclosure both firing out in a conventional manner. I want these drivers in phase to cancel out cabinet resonance in an effort to not transmit energy directly from the cabinet to the structure. We're on the same page, right?

One more thing, that high pass filter thing that Matt linked, that would be a good thing to throw into the mix, wouldn't it?

 

[fuzz092888]

I was using the term 'dual opposed' and I see you use the term 'push-pull'. I saw an image for 'push pull' that certainly didn't look like what I wanted. Just to be clear: I want drivers on opposite ends of the enclosure both firing out in a conventional manner. I want these drivers in phase to cancel out cabinet resonance in an effort to not transmit energy directly from the cabinet to the structure. We're on the same page, right?

Unless my understanding is off, push pull means that both drivers are moving the in same direction at the same time. This could mean that they are facing the same way or opposite directions.

Dual opposed is what I built where they're facing away from each other and firing in different directions so that internally the backwaves cancel each other out.

Yes, adding the fmod high pass will keep the sub from trying to reproduce anything down super low which will hopefully lower power requirements a touch and keep the drivers operating well within their clean limits.

 

[TLS Guy]

I think you are on the right lines.

First of all you will not get a sealed sub of that size, to get close to your low extension without Eq. So if you don't want Eq you need a ported sub.

Now I know exactly what you had in mind about driver placement. The model has only opposed on the same baffle. However the design is the same except the wiring diagram. You want the drivers to move in and out together obviously. So you wire the drivers in phase not as shown on the model diagram. I would still do the Laurie Fincham trick of mounting the drivers with threaded bar going from one side to the other. That will enhance vibration cancellation and add bracing.

Those new drivers with very low profile and volume, do make a small footprint sub possible, although in your case at about half power. But as you know that only looses you 3db. If you build that sub you will have plenty of power for your modest requirements.

In our Eagan town home the built in coupled cavity subs in the mains have much less output than yours, (f3 27 Hz), but I still worry about annoying the neighbors and have to be careful. So I'm not worried about you using the tube port in your situation. You will best your current subs by leaps and bounds.

As to a high pass filter, I would not use that in line passive device. If you want this, you need an active filter with subs of this quality.
Personally, I don't think a high pass filter is necessary in your case. If you look at the model, cone displacement is only 3 mm at full power! It does not exceed xmax until around 20 Hz at full power. With the way you intend to design and use these subs you will not damage those drivers. The tuning is controlling the drivers text book, by the model. Your sub is only 12 db down at 20 Hz, so with room gain you will have useful low extension. In fact even with the port giving you power limitations, you will still have to be careful not to get complaints from the neighbors.

I personally think you have chosen the right approach for your situation. We can model drivers for ever, but as you can see in these models, cabinet volume more than any other single factor determines the performance. There is no fee lunch. This is actually why I did five models, to drive this point home.

By the way, there was a typo I noted in the tube vent length. The length is 14.3". This is measured from end of flare to end of flare. The parts are readily available.

 

[jcparks]

I tried telling her who you are. She said, "no".

I think I have had a similar conversation with my wife...

 

[ARES24]

I think I have had a similar conversation with my wife...

Uh... it would be more impressive if someone here had the opposite conversation