Recommendations for 8" Subwoofer and Amp?

[weinstro]

Hi,

I'm purchasing a SqueezeBox Boom for the kids for Christmas, and would like some recommendations for a decent, but not very expensive, subwoofer / amp combo.

The Boom includes biamp'd digital amplifiers, set at 2kHz LR4. Really. It also includes a subwoofer out set at 100 Hz, also LR4. Room size is 12' x 12'. Likely location is quarter space (floor / wall intersection, but not corner).

Target price is $100 for both driver and amp. $200 would be where my resistance to buy increases exponentially, my "F10", if you please.

For the amplifier, I have no strong preference, but probably don't need a built in crossover. I like the idea of a plate amp, though, but something LM3886 based would probably be adequate.

My short list includes the following drivers:
- MCM 55-2421
- Usher 8137A
- Peerless 830586 (NLA), 830667, 830869
- Dayton DCS205, QT210, SD215, RS225

Preference is for low distortion over max SPL. I'm willing to consider some interesting approaches, i.e., series capacitor to extend response, etc.

Suggestions?

Thanks,

Rob

[evilskillit]

At this price this sub is hard to resist.

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=295-480

That, a couple of passive radiators and a cheap amp and you're right where you need to be. I think there is even a design for that.

There are a ton of options but I think that one is the best boom for the buck. Or if you can find the Logitech Tangband sub cheap on e-bay they rock, but I don't see any on there right now.

[andykriech]

Hi,

I'm purchasing a SqueezeBox Boom for the kids for Christmas, and would like some recommendations for a decent, but not very expensive, subwoofer / amp combo.

The Boom includes biamp'd digital amplifiers, set at 2kHz LR4. Really. It also includes a subwoofer out set at 100 Hz, also LR4. Room size is 12' x 12'. Likely location is quarter space (floor / wall intersection, but not corner).

Target price is $100 for both driver and amp. $200 would be where my resistance to buy increases exponentially, my "F10", if you please.

For the amplifier, I have no strong preference, but probably don't need a built in crossover. I like the idea of a plate amp, though, but something LM3886 based would probably be adequate.

My short list includes the following drivers:
- MCM 55-2421
- Usher 8137A
- Peerless 830586 (NLA), 830667, 830869
- Dayton DCS205, QT210, SD215, RS225

Preference is for low distortion over max SPL. I'm willing to consider some interesting approaches, i.e., series capacitor to extend response, etc.

Suggestions?

Thanks,

Rob

Do you have size restrictions or desires? I have built both a Biumph and a Triumph (Wolf's super small designs). They both work really well with a set of small satelites (Wolf's Rubycks). their bedrooms are both about the same size 12x12ish, so output is plenty, at least for their usage and that is with reasonably loud hip-hop, etc.
Best thing is very small size and the PE 25w amp works great with it.

Another suggestion is RJB's Cerberus sub. uses a TB 6.5" sub and is fairly small, as well. Good output. Works great with his Microbes.

I realize that neither of these suggestions are 8" subs, but thought I would throw them in FWIW.

Andy.

[fastbike1]

How about the minimum fuss route?

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=300-631

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=309-176

Should work just fine w/ the Boom

[Wolf]

I would use the SD215 as well! Great bargain for a sub.

Later,
Wolf

[kornphlake]

SD215 for $15 with a Foster plate amp for $35 from Jack Hidley comes to about $75 after shipping. It looks pretty good in a vented box about 2 cu ft tuned to 30hz or slightly lower.

I built a sub using this driver in a .875 cu ft vented enclosure tuned to about 30hz, I intended to put it under the rear bench in my wife's van (long narrow enclosure made a long port easy enough to incorporate) but I made a mistake when I measured the space under the bench and it didn't quite fit. I've been meaning to build a new enclosure but haven't had time, it's been in the house for a couple weeks and it sounds pretty good with music, we watched Up on Sunday and I hooked it up to the TV with some bookshelf speakers and it sounded good as well even though winISD predicts the sub starts to roll off around 60hz and is -3db at 40hz.

[johnnyrichards]

The Allison linked would probably be a great bang-for-the-buck setup, likely way better than the Dayton 8" and at least as good as anything you could do with the Dayton SD-215.

I can't believe there are any of the shielded 8" left at that price, I was thinking they would have been gone in two days. PE either is sitting on 876,000 of them or they are not as popular as I thought. Still, $15 for almost any 8" driver is a nice price - and a steal for this one.

[weinstro]

Wow, lot's of great suggestions. I'm overwhelmed.


At this price this sub is hard to resist.

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=295-480

That, a couple of passive radiators and a cheap amp and you're right where you need to be. I think there is even a design for that.

I think it's called a Triska.


SD215 for $15 with a Foster plate amp for $35 from Jack Hidley comes to about $75 after shipping. It looks pretty good in a vented box about 2 cu ft tuned to 30hz or slightly lower.

Where and how do I order that?


How about the minimum fuss route?

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=300-631

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=309-176

Should work just fine w/ the Boom

Tempting. Very tempting.

Regards,

Rob

[Steve Henry]

And how do I order that?

http://home.comcast.net/~jhidley/

[johnnyrichards]

I've done three builds with that NHT amp, it is rock solid. you may want to investigate how the 29Hz 3rd order high pass and "spectral tilt" will impact what you want to do, though.

[kornphlake]

When I bought my plate amp last month Jack offered it pre-modified with the high pass adjusted to 20hz for only $5 more. I didn't stress too much about the high pass or spectral tilt and bought the amp that had already been modified.

[kmibb]

I suggest a vented 8" Quatro with a Jack Hidley amp. Definitely remove the boost though.

[edlafontaine]

Options for the DVC 8 are in this thread:

http://techtalk.parts-express.com/showthread.php?p=1568902#post1568902

[kduggan]

Dayton DVC 8 and the Dayton 70 Watt plate amp work well in a 1.1cuft ported enclosure. I have built six and all work great in a variety of situations and room sizes.

[weinstro]

Options for the DVC 8 are in this thread:

http://techtalk.parts-express.com/showthread.php?p=1568902#post1568902

Thanks, I got the message on the SD215!

DLR has a great write-up on Zaph's site where he explains a bit of the rationale for selecting a PR, but I get a little lost when trying to trade off mass and volume. Before I start crawling all over Unibox, are there any tips or rules of thumb with respect to a passive radiator, like shape of curve, etc.?

And before I whip out the card, is there any distortion data available on the QT210, just to do a sanity check?

Regards,

Rob

[thekorvers]

[quote=kornphlake;1683793]SD215 for $15 with a Foster plate amp for $35 from Jack Hidley comes to about $75 after shipping. It looks pretty good in a vented box about 2 cu ft tuned to 30hz or slightly lower.

+1

2 cu ft tuned to 30 Hz. Save yourself the cost of a P.R. and use a 4” diameter ABS pipe of + 16” length. Use an elbow if necessary to fit. Or use a slot port, same surface area, following 2 sides of the enclosure, using 45 degree corners.

[fbov]

Dayton DVC 8 and the Dayton 70 Watt plate amp work well in a 1.1cuft ported enclosure. I have built six and all work great in a variety of situations and room sizes.

I've built the Triska (DVC shielded/passive radiators) so I've modeled a lot of options for the DVC and other subs of that size (Still have one to build...). Froim a simulation standpoint, I thnk the new, unshielded one looks much nicer (ported ~1 cu ft) than the shielded driver ever does, and 70W is likely good based on my application with the 2.1 plate amp (50W sub power).

Have fun,
frank

[johnnyrichards]

I've built the Triska (DVC shielded/passive radiators) so I've modeled a lot of options for the DVC and other subs of that size (Still have one to build...). Froim a simulation standpoint, I thnk the new, unshielded one looks much nicer (ported ~1 cu ft) than the shielded driver ever does, and 70W is likely good based on my application with the 2.1 plate amp (50W sub power).

Have fun,
frank

I already swapped out the shielded 8" in my Datum sub for the non-shielded version and it does seem much more suited for the "small on purpose" alignment I employed for the shielded.

[weinstro]

[quote=kornphlake;1683793]SD215 for $15 with a Foster plate amp for $35 from Jack Hidley comes to about $75 after shipping. It looks pretty good in a vented box about 2 cu ft tuned to 30hz or slightly lower.

+1

2 cu ft tuned to 30 Hz. Save yourself the cost of a P.R. and use a 4” diameter ABS pipe of + 16” length. Use an elbow if necessary to fit. Or use a slot port, same surface area, following 2 sides of the enclosure, using 45 degree corners.

Thanks for the tips. Some insight please....

I ran some Unibox simulations for the SD215-88, QT210, and Usher 1001A (I have an orphan in the garage; I forgot I had it laying around). I used the manufacturer's published values for T-S parameters. I adjusted power to keep Xmax below it's max above Fb. For the QT210, this was 90W. The other drivers will hit Xmax above Fb at around 30W. The GIF is uploaded, but the resolution is miserable, just enough to make out shapes.

Legend:
Blue = Usher 1001A
Lt Green = QT210
Dark Green = SD215
Red = SD215 with 12" PR

On the latter, I simulated a configuration recommended elsewhere on PE, but I can't see what the fuss is with a PR for this driver (SD215). Am I missing something? Like maybe room gain or the effect of the plate amp EQ?

Any particular reason not to use the Usher, given the price ($0)?

Regards,

Rob

[Mayhem13]

+10 for the SD215-88 and the Foster amp modified in 2cuft ported. I'm doing a DIY design for the forum with this combo as we speak. Using a PR with the added cost in a budget design make almost 0 sense IMO. What's to be gained other than a half a foot of floorspace.

Now, considering your Usher, there's absolutely no reason not to build a sub using it. It's a great driver with extremely low HD. It's simply a bit excursion limited but is suspect even outside of the gap and non-linear it's distortion profile is lower than the SD215-88.

[kornphlake]

On the latter, I simulated a configuration recommended elsewhere on PE, but I can't see what the fuss is with a PR for this driver (SD215). Am I missing something? Like maybe room gain or the effect of the plate amp EQ?


If I understand correctly (unlikely) the passive radiator should model the same as a port if both are tuned to the same frequency. The benefits of a passive radiator are 1) you don't have to worry about port noise, 2) a passive radiator can be used in short or shallow boxes that would be too small to reasonably tune with a port and 3) they look just like a driver so you can fool your friends.

The Triska sub is what has caused the fuss over the passive radiator, the goal was to build a small sub (<1 cu ft) and tune it to ~40 hz, the port needed to tune an enclosure this size is about twice the length of any of the enclosure dimensions so in this case the passive radiators make sense, it keeps the sub small and cube shaped without requiring a complicated port. I don't think there's really any hype around the passive radiators, they were chosen for one sub design using the SD215 due to a couple of design goals. The SD215 models a bit better in an enclosure large enough for a reasonable length port.

[edlafontaine]

The SD215 models a bit better in an enclosure large enough for a reasonable length port.

+1 bingo

[weinstro]

If I understand correctly (unlikely) the passive radiator should model the same as a port if both are tuned to the same frequency. The benefits of a passive radiator are 1) you don't have to worry about port noise, 2) a passive radiator can be used in short or shallow boxes that would be too small to reasonably tune with a port and 3) they look just like a driver so you can fool your friends.

The Triska sub is what has caused the fuss over the passive radiator, the goal was to build a small sub (<1 cu ft) and tune it to ~40 hz, the port needed to tune an enclosure this size is about twice the length of any of the enclosure dimensions so in this case the passive radiators make sense, it keeps the sub small and cube shaped without requiring a complicated port. I don't think there's really any hype around the passive radiators, they were chosen for one sub design using the SD215 due to a couple of design goals. The SD215 models a bit better in an enclosure large enough for a reasonable length port.

OK, that makes sense. If I look at dlr's write-up of the Chameleons (on Zaph's site), there's a really clear benefit with using a PR. FWIW, I have a pair of Peerless 830860 drivers in the garage somewhere, and they show a marked response improvement with a PR, too. Must be a Peerless thing.

However, I didn't see this with the SD215. In fact, it looks worse for the conditions I explored. I uploaded a low res screen shot of Unibox on post #19. Near as I can tell, PR's work well only in certain situations, but I still haven't picked up on the criteria.

Regards,

Rob

[kornphlake]

OK, that makes sense. If I look at dlr's write-up of the Chameleons (on Zaph's site), there's a really clear benefit with using a PR. FWIW, I have a pair of Peerless 830860 drivers in the garage somewhere, and they show a marked response improvement with a PR, too. Must be a Peerless thing.

However, I didn't see this with the SD215. In fact, it looks worse for the conditions I explored. I uploaded a low res screen shot of Unibox on post #19. Near as I can tell, PR's work well only in certain situations, but I still haven't picked up on the criteria.

Regards,

Rob

I haven't used unibox, does it run the calculations for a passive radiator automagically? As far as I know a passive radiator should model the same as a port if both are tuned to the same frequency in the same size enclosure.

If I understand correctly, a port is a mass of air calculated by multiplying the volume contained within the port by the density of air, a passive radiator is a membrane with the same mass as the equivalent port, either serve to dampen the enclosure. The driver shouldn't discriminate between a passive radiator and a port, if you're seeing a difference I suspect it is because you aren't comparing the two under identical parameters. I could be wrong though, it wouldn't be the first time.

It looks like in the example of the Chameleons the ported box and the box with the passive radiator are slightly different in terms of tuning frequency and box volume (because the passive radiator takes up space in the box presumably) one box has the walls lined, the other is stuffed, etc. I'd guess a handfull of minor differences are what makes the graphs look different.

I cant' remember the numbers but I calculated that a box tuned to with a passive radiator needed a stupid amount of weight, about 3 cubic inches of steel. I don't think the passive radiators are strong enough to hold that much weight and the included screw isn't nearly long enough to hold that many washers, I'd have needed a custom machined cylinder with a counterbore for the mounting screw.

[weinstro]

I haven't used unibox, does it run the calculations for a passive radiator automagically? As far as I know a passive radiator should model the same as a port if both are tuned to the same frequency in the same size enclosure.

Unibox is basically a fancy Excel spreadsheet. It has a separate sections/forms on the same page. There are sections for driver data, sealed box, vented box, passive radiator, and bandpass box.

You have to enter the parameters for the passive radiator, and then fiddle with the mass and volume to get the tuning you like. None of this is automagic.

For the second statement to be true, then passive radiator mass and compliance would have to be equivalent to the air mass and compliance in the port tube. But those initial conditions are determined by the manufacturer's data for the passive radiator. Not impossible, but a serendipity moment.


If I understand correctly, a port is a mass of air calculated by multiplying the volume contained within the port by the density of air, a passive radiator is a membrane with the same mass as the equivalent port, either serve to dampen the enclosure. The driver shouldn't discriminate between a passive radiator and a port, if you're seeing a difference I suspect it is because you aren't comparing the two under identical parameters. I could be wrong though, it wouldn't be the first time.

Hmm. Well, I've been running on 4 hrs of sleep for several days, so my thinking could be skewed, but the relative compliances of the passive radiator and air mass need to enter into this somewhere. At some point, this is the deaf leading the blind, you know. :)


It looks like in the example of the Chameleons the ported box and the box with the passive radiator are slightly different in terms of tuning frequency and box volume (because the passive radiator takes up space in the box presumably) one box has the walls lined, the other is stuffed, etc. I'd guess a handfull of minor differences are what makes the graphs look different.


Well, I'm OK with optimizing the enclosure volume once a topology has been selected, i.e., sealed, vented, passive radiator, something else. My sense is that there is a sweet spot for passive radiators that depends on the driver parameters and enclosure volume.


I cant' remember the numbers but I calculated that a box tuned to with a passive radiator needed a stupid amount of weight, about 3 cubic inches of steel. I don't think the passive radiators are strong enough to hold that much weight and the included screw isn't nearly long enough to hold that many washers, I'd have needed a custom machined cylinder with a counterbore for the mounting screw.

A downfiring application might be interesting...

Like with a lot of simulation tools, the engineer needs to look up from time to time and see if the results are consistent with real world limitations. Unibox is no exception in this regard, either.

Thanks for taking the time to write.

Regards,

Rob

[2leftthumbs]

If you're still in the planning stages I notices these at madisound:
https://www.madisound.com/store/product_info.php?products_id=9007
which I would presume uses this driver:
https://www.madisound.com/store/product_info.php?products_id=8991