8" sub choice for "small" Bluetooth system

maxximus

Member
2014-02-22 2:11 am
I'm building a 2.1 Bluetooth system. It will be powered by a rc battery. I have already got the speakers two Tang Band W3-881SJF 3" Full Range Speakers. I'm looking to add a 8" sub into the smallest box possible. I was looking at the GRS 8SW-4 8" Poly Cone Subwoofer 4 Ohm

However I stumbled on the JL 8W3v3-4 8W3v3-4 - Car Audio - Subwoofer Drivers - W3v3 - JL Audio

This JL goes into a smaller box 10x9x9 if I use 1/2 with some bracing.
The grs would be a 10x13x13 box. However it costs much less.

If anyone has any experience with either driver, feel free to chime in, or if a better one comes to mind add that one as well.
 

TBTL

Member
2013-10-08 12:26 pm
"The smallest box possible" is a bit vague. Maybe you can fix your box size and desired low frequency cutoff first. The maximum achievable efficiency will follow from those.

Then the search can start for a woofer that works in that box and reaches this lower cutoff.
 

maxximus

Member
2014-02-22 2:11 am
For box sixe I am thinking a 9 or 10 inch cube. I am crossing at 100hz, because the system will be modular so I can use the speakers with or with out the sub. At 100hz the speakers still sound good. Because it going to be run off of battery power I am looking for a sub in the 100w range. I don't want something that consumes power, also I want it to cross well with the 3" tang bands
 
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Unless I am reading it wrong that sub is calling for a much larger box.
And vented one at that. A 9-10" cube is .3-.4 cuft box. Thus the two
driver I noted in the top of the thread, the GRS and JBL

Hi,

Your reading it wrong. It works in tiny sealed boxes,
(though it is best used with a PR in an about 10L box).
The GRS certainly doesn't, and the JL is very expensive.

rgds, sreten.

http://www.diyaudio.com/forums/subwoofers/80138-sillys-1st-sub-8-mcm-55-2421-a.html
 
Hi,

I'm not sure you understand what criteria you are dealing with at all.

A passive 100Hz x/o is totally out of the question, and assuming
active "would cross nice" is totally irrelevant to the question.

You really don't want a bass unit with 1.5mm Xmax, ever.

rgds, sreten.
 
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maxximus

Member
2014-02-22 2:11 am
Yes this is a bit new for me. I already have the Tang bands and some crossovers that cross at 700 hz But they don't sound right. I know I don't have the sub to fill in the gap yet, but I would like to cross them as low as possible. The plan is to have everything modular so I can run either the two speakers by themselves or add in the sub.

I have never built a sub box as small as 10x10 so I am just a bit worried a driver not designed to run in such a small box will run right. Sound quality is more important than spl for me.

For the price the MCM Audio Select 8'' High Excursion Woofer - 120W RMS 4ohm | 55-2421 (552421) | MCM Audio Select Is worth a try, I just didn't want to waste my money if it didn't sound right. I'm not doubting you have more experience with this than me, its just the description and specs look like that sub is designed for a much bigger vented box.

What is the lowest you would cross the TB's in such a set up?
 

maxximus

Member
2014-02-22 2:11 am
Ok I know it is not an 8", but I think this one would work nice.
Tang Band W6-1139SIF 6-1/2" Paper Cone Subwoofer Speaker

With the two 3" speakers included into the enclosure with the 6.5 using the box size recommended I would be around a 8" cube using 1/2 inch plywood. I may do 3/4 inch for the subwoofer face and add internal bracing as well. I think crossing this with my 700hz crossovers would sound acceptable.

It would definitely be more portable, and should give me longer battery life.
 
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I'm building a 2.1 Bluetooth system. It will be powered by a rc battery. I have already got the speakers two Tang Band W3-881SJF 3" Full Range Speakers. I'm looking to add a 8" sub into the smallest box possible. I was looking at the GRS 8SW-4 8" Poly Cone Subwoofer 4 Ohm

However I stumbled on the JL 8W3v3-4 8W3v3-4 - Car Audio - Subwoofer Drivers - W3v3 - JL Audio

This JL goes into a smaller box 10x9x9 if I use 1/2 with some bracing.
The grs would be a 10x13x13 box. However it costs much less.

If anyone has any experience with either driver, feel free to chime in, or if a better one comes to mind add that one as well.
The Car Audio woofer is only 83dB SPL efficiency. That's real bad. Most Hi-Fi woofs are around 88dB+. A 3dB difference is like cutting the power amp output by half. With this woof, you'd get the equivalent of 1/4 the sound power as compared with most Hi-Fi woofs of that general type and size, per unit of power amp output. I'd use a Peerless 8 incher as a reference. The Nomex cone is very good. In the case of a battery powered amp, efficiency should be one of the top priorities. Right behind that I'd look for Xmax, which will usually be a tradeoff with efficiency. Peerless may well be the best buy for speaker drivers in general, and their better ones compete well with the most expensive drivers of any brand out there.
 

maxximus

Member
2014-02-22 2:11 am
Thanks I agree with you the Peerless has the best specs I have seen for a 8" in a small sealed box. However if I do a 10" box that is almost half the size called for.

Including the speakers I could do a 7-8" box with the tang band sub and be very close to the designed enclosure size the drivers are designed for.
With the peerless I am looking at a 10-11" box, but box size is still much smaller than at least the sub is designed for.

For a mid volume comparison between the peerless and the 6.5 tang band sub what would sound better? I realize this is also quite subjective and real world application can vary from computer simulation. Maybe I'll have to build both and sell the one I like the least!
 
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maxximus

Member
2014-02-22 2:11 am
Seeing how important a small box size I'm actually starting to lean towards a 6.5 inch woofer/sub. I have never played with one of these so it will be interesting. It should cross very easily with the 3" tang bands.

Now the question is what is the better driver? The mcm or the tang band. I only have a 100 watt amp if that makes much difference.
 
Seeing how important a small box size I'm actually starting to lean towards a 6.5 inch woofer/sub. I have never played with one of these so it will be interesting. It should cross very easily with the 3" tang bands.

Now the question is what is the better driver? The mcm or the tang band. I only have a 100 watt amp if that makes much difference.
That "great" driver mentioned above has a foam surround suspension. Foam disintegrates over time, and is often falling apart 10-15 years later. Take a look at the Peerless 6.5 inch Nomex cone woofer. I have some and like them a lot. Good Xmax, vented spider, rubber surround suspension, and the resonance in the upper midrange is manageable without needing a high order crossover.

The harder cone woofers have slightly better resolution, but always seem to have a pretty severe resonance in the upper midrange, right where the ear is most sensitive (3kHZ - 5kHZ). Polyproylene has next to no resonance there, and might be the best choice for a newbie who will be using a passive crossover. Metal and Kevlar has a severe resonance there, which often requires a high order crossover network to attenuate that enough.

If you can build an active EQ to pump up the low end, you could end up with amazing bass out of a few of the 6.5 inch Peerless Nomex drivers. I have a circuit to share that does that if you're interested. +10dB at 33HZ, with a fast rolloff below that. Low bass pumped up will eat the batteries faster, and outdoors you may not hear it much anyways, so it's a tradeoff. What are the specs on the battery? Voltage and watt hours?
 

maxximus

Member
2014-02-22 2:11 am
It is a 4 cell 14.7v 5000mah battery

I have found listening to the 3" tang bands I like them better without a crossover. What would be the best way to use the least crossovers in this setup? I'm thinking I could maybe get away with just doing a crossover on the sub. Or if I even get the right sub and set the volume correctly on it, it may sound good as well.

As for bass boost I don't have much desire for that, otherwise I would be insisting on the 8":)
 
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