8" Subs Vs. Larger Subs

[Kirghiz]

Depending on who you talk to, people scoff at the notion of using 8’s as subwoofers. They’re small, don’t handle as much power as bigger subs, and really they aren’t much to look at. Where I am having to install my subs under the back seat of a crew cab pickup I have been looking really close at small box subs, and in particular the depth of the subs, because that is where my biggest issue lies. I actually have a single Ti2 10” sub ported under there now, and it sounds great for 1 10” sub, but I was skeptical about whether one 10” would satisfy my needs when I did it, and now I am looking for more. A single Ti2 12” will actually fit ported, 2 10” subs would be tight ported but will definitely fit sealed, and I might do either of those things, but here is something else I have been looking at. Here are the specs of an 8” driver I have been looking at. I’m not going to say who the brand is because the purpose of this isn't to talk up someone else's product, but it is a company that has been making car audio since forever, and the driver is one that can be found for $100-$120 all over the place. It has also gotten pretty good reviews as an SQ driver, so it isn’t just some high excursion SPL driver. If Phoenix Gold made an 8" I'd use theirs as the example, but they don't.

8" Sub
Power Handling: 350w rms
Sensitivity 1w/1m: 83.5 db
Freq. Response: 28-200hz
QTS: 0.50
XMax: 14mm
Peak To Peak: 52mm
Cone Area: 201cm squared
Recommended Ported Enclosure: 0.25-0.60 Cu3
Mounting Depth: 4.525”

Now, here is my other best real option, the Ti2 10”
Power Handling: 600 watts
Sensitivity 1w/1m: 91 db
Freq. Response: 20-200hz
QTS: 0.59
Xmax: 12-14mm (They don’t list it in the specs, but it’s that or less)
Peak to Peak: 40mm
Cone Area: 370cm squared
Recommended Ported Enclosure: 1.25-2.0 Cu3
Mounting Depth: 6”

To get a pair of the Ti2 10” subs in a ported box it would require 2.5-4.0 Cu3 of space, it could take 1200 watts rms of power, and you would have 740cm2 of cone area with a 12-14mm XMax and 40mm peak to peak excursion. Yes, the sensitivity and freq. response is great on these subs. Just for information sake, the 15” Ti2 sub has a cone area of 830cm2, 7.5” depth, and requires 3-4 cu3 for a ported enclosure.

Now, if you look at 4 of those 8” subs, a ported box would be from 1.0-2.4 cu3, it would take 1400 watts rms, and would have 804cm2 of cone area with 14mm XMax and 52mm peak to peak travel.

On paper it looks as though the 4 8’s ported would move at least as much air as 2 10” subs or a single 15” sub ported, would do it in less than half the enclosure space, and could do it in a much skinnier enclosure in general than you could make work with a bigger sub. I’m not picking on PG’s subs, I have one and love it, and will likely end up buying another one. These numbers really work against just about any other brand of 10”, 12”, and 15” sub out there, so it is just the general premise I am looking at.

I’m trying to understand why four 8” subs wouldn’t equal the output of a pair of 10” subs or a single 15” sub. I understand the idea that four 8” drivers will cost more, and I understand the idea that it would require more power, but if one is in a tight spot on enclosure space, wouldn’t this be a viable option if cost and power wasn’t a problem?

For that matter, one could do eight 8” subs in the same size enclosure as a pair of 10” subs or a single 15” sub and have 1608cm2 of cone area, roughly equal to 2 15’s or four 10’s. Enclosure for enclosure, wouldn’t those 8’s be louder, even with the same total power on each box?

What is it that I am missing?

[LowandLoud]

Your logic makes sense to me. And 8's are a viable option, especially when pressed for space. I have been surprised by a few 8's before but have never used any. The one thing i have noticed personally is that the larger the sub, the deeper the bass seems to be. I have always used 10's prior to my current setup because i like the punchy feeling that larger subs seem to lack in my experience. I have no doubt there are exceptions to this but in every stereo i have built or helped build this is the case.
For example, a friend of mine built a Mazda p/u with 4 18" subs in the extracab. Im not sure what amps or how much power he had(16 years ago), but it was damn loud. You could hear it for blocks. You could sit in it and there was air movement but would not skip your heart. My same body style truck with 2 10" behind the seats would sometimes take your breath away when it hit, but with the windows up from 30 ft away, you could barely hear it.
I think it really depends on personal preference, how loud you listen, type of music you listen to the most and what you want out of your system.

LL

[ttocs]

I ran 4 mb qyuart 8's in my mustang for a while to fit area. Honestly they sounded great, for 8's but I am looking forward to hearing 10s in there now(3 of them).

[zeropoint0.5]

no personal experience,

but i was told these should be bad ass 8 inch subs.............


http://www.jlaudio.com/8w7ae-3-car-audi ... vers-92117

[Kirghiz]

Your logic makes sense to me. And 8's are a viable option, especially when pressed for space. I have been surprised by a few 8's before but have never used any. The one thing i have noticed personally is that the larger the sub, the deeper the bass seems to be. I have always used 10's prior to my current setup because i like the punchy feeling that larger subs seem to lack in my experience. I have no doubt there are exceptions to this but in every stereo i have built or helped build this is the case.
For example, a friend of mine built a Mazda p/u with 4 18" subs in the extracab. Im not sure what amps or how much power he had(16 years ago), but it was damn loud. You could hear it for blocks. You could sit in it and there was air movement but would not skip your heart. My same body style truck with 2 10" behind the seats would sometimes take your breath away when it hit, but with the windows up from 30 ft away, you could barely hear it.
I think it really depends on personal preference, how loud you listen, type of music you listen to the most and what you want out of your system.

LL

For giggles I did a search for an 18" to get a rough SD, and found the Obsidian 18" first which has a cone area of 1217 cm2. That is roughly equivalent to three 12" subs or six 8" subs. If he had four of them it was equivalent to twelve 12" subs or twenty-four 8" subs. You should have heard him from blocks away. LOL

Back in the late 90's I heard tell of a van that had 56 8" subs in it that topped 150db. I think it broke the record at the time. The dude with the Blazer with the Fosgate gear that Fosgate was so proud of held it before that, and broke it again shortly thereafter, but the magazines made a big deal of it when it happened. The 8's were installed in a tunnel type enclosure, 14 on the floor, each wall, and on the ceiling, and I think he only had like 100 watts going to each one. I remember it because it was so different from what everyone else was running. With the technology that DD and Sundown put into their 8's these days, a build like that with DD 1508's or Sundown SA-8's would post some crazy numbers.

But I'm not going for a bonecrushing SPL build. I want it to sound good, but get as loud as possible in the space I've got. The JL 8w7 has a depth of 6.83" inches, requires 1 cu3 ported, and costs $400+. It wouldn't fit for what I'm doing (too deep). If I was going with only one 8" sub in a Corvette or something that'd probably be it though. Small box subs that are cheap ($150 or less) seem like they'd work best if one were trying to get big sub performance from a bunch of them. The specs I used in the example 8 in the OP are from the new Alpine Type R's fwiw. If I decide to try four 8's in this truck it's pretty much going to be them I think. I'd go with Phoenix Gold Ti2 8's without a thought if they existed because this Ti2 10" I have sounds so damn good though.

[vladthebad]

Look at the crap efficiency on that 8. With 4 of them, your still getting ~2db less output with 4 watts(1 each) than 1 watt on the 10. Now lets add power...

400w on 8s vs 100w on 10, the 8s are still not as loud... 1400w on the 8s (max rms) = 2db less than 350w on the 10. May not matter if you've got the enclosure gain or the cabin gain or power to burn, but if you are alternator and power limited, it might be worth finding a slightly more efficient 8.

[gfunk_nz]

I'm trying to complete my wheel well install in my Golf four 4 SA8 v2's, I've got a sundown 2500 to power them so should be getting about 600rms each. They are in a ported box, tuned to 33Hz, hopefully it's got enough glass in it as it should move some air, but with the 33hz tuning I'm planing on it playing nicely. I had always run 12's or larger, but ended up playing with a single sundown E8 and was well impressed, so thought why not go with 4 of the silly 8's for when I want it to get really loud. It will be interesting to see how it sounds!

[Kirghiz]

Look at the crap efficiency on that 8. With 4 of them, your still getting ~2db less output with 4 watts(1 each) than 1 watt on the 10. Now lets add power...

400w on 8s vs 100w on 10, the 8s are still not as loud... 1400w on the 8s (max rms) = 2db less than 350w on the 10. May not matter if you've got the enclosure gain or the cabin gain or power to burn, but if you are alternator and power limited, it might be worth finding a slightly more efficient 8.

I pretty much decided this morning that I really like my Ti2 10", so I'm probably just going to bump up to the 12" if another 0.2 or 0.3cu can be found for the enclosure.

That being said, let's say Phoenix Gold made an 8" in the Ti2 line, and it had a hypothetical sensitivity of 89db, which it likely would if they used the same tech. What then does that do to the numbers you posted? That being said, XMax and total cone area counts just as much as the sensitivity. Some would argue that they count more, but that's another thread.

[vladthebad]

At 89db 1w/1m you'd be talking two 8s, each with same power as the 10, 8s would be a undetectable bit louder than the 10. Four 8s would put you 3db up, so 'twice' as loud. Realistically need 10db gain to sound twice as loud to your ears and brain though.....

[Kirghiz]

.....but 4 8's would have more than twice the cone area. Really the four 8's would effectively have the cone area of a 15", so on that token alone the 8's should hit a hell of a lot harder than the single 10", regardless of the sensitivity.

If cone area was irrelevant and sensitivity was all that mattered then they would have long since built a 6.5" driver with a 97db sensitivity that can take 1000 watts and been done with it. Sensitivity matters, but it is only one facet of the equation.

[dwnrodeo]

.....but 4 8's would have more than twice the cone area. Really the four 8's would effectively have the cone area of a 15", so on that token alone the 8's should hit a hell of a lot harder than the single 10", regardless of the sensitivity.

If cone area was irrelevant and sensitivity was all that mattered then they would have long since built a 6.5" driver with a 97db sensitivity that can take 1000 watts and been done with it. Sensitivity matters, but it is only one facet of the equation.

Yes, four 8" subwoofers would have the cone area of one 15" subwoofer and while greater cone area and xmax help with sound pressure levels, efficiency also plays a huge part. Having four 8" subwoofers of lower efficiency than one 10" subwoofer doesn't exactly mean higher sound pressure levels if you only have a limited amount of power to give to the speakers despite the larger cone area. For example, I have an SSA DCON 12" subwoofer with efficiency 2 db @ 1w/m lower than my SSA XCON 12" subwoofer with larger xmax and potential for higher sound pressure levels. However, I do not have enough amplifier power to feed the XCON so my DCON is noticeably louder because of its higher sensitivity.

http://www.bcae1.com/speaker.htm

Note:
You have to be careful when looking at reference efficiency (sensitivity). You can make a speaker really efficient by designing the voice coil to fit entirely in the magnetic gap. This would likely yield a sensitivity of 104 or so. This speaker may work very well if powered by a low powered amplifier because of the high efficiency but would not be able to produce high SPL at low frequencies because it would have a very small xmax. Actually, if the voice coil length was the same as the height of the magnetic gap, it would have no (zero) xmax.

You can also design speakers for very high power handling and high SPL but those speakers would likely have a very low reference efficiency. Speakers designed for high SPL in cars generally have a larger xmax and therefore lower reference efficiency but would easily out perform the speaker (in the previous example) with the higher reference efficiency at low frequencies.

[vladthebad]

Cone area isn't always what it's cracked up to be.... Unless we are comparing similar Xmax drivers, in the realm of similar Qts, and similar style/tuning enclosures. Furthermore, on some of the 8's with higher Xmax that I've seen, the cone area is 'tiny' due to a huge surround. Why, I have no idea, it certainly didn't have that much Xmax or movement. Also, I was talking two 89db 8s instead of 4.... And again, now we aren't talking a massive difference in cone area. (Less than 3db) With 4, you'd obviously get louder. Not sure what kind of 8 you'll get 4 of to actually handle power on though in that small of an enclosure, unless its sealed, or you mount them compound iso. (Then height becomes an issue) I'd stick with the 10 if you have it and it sounds nice. Lot of work and money and extra power for not much gain on the 8s

[ttocs]

the only thing I didn't like about my 4 - 8" set up was the on thing that multiple drivers could not fix, they just didn't like to play low enough. I like some techno/electronic music with some good bass to it and they could put out the spl to suprise you, maybe say on a rock song but on a rap/techno song they quickly showed their weakness. One weakness a sub should never have is the ability to play low but unfortunatly the size of the 8 just makes it hard. Another reason I am looking forward to having 3 -10s. IMO a 10" is a good mix of fast-slapping bass and still has enough girth to it to be able to touch the bottom of what you want too hear, everything an 8 isn't really.

[Kirghiz]

I love this forum compared to other car audio forums. In other places people would come at you like you slapped their Momma for bringing this discussion up.

There are some 8's out there that get down on the lower end very well, though they are expensive generally and require a bigger box, which defeats the purpose of having 8's. The Sundown SA's are sort of an example of that, though people regard them as SPL subs, but owners of them scream that they are musical too. I researched them extensively before getting what I have. Some say to fit 4 ported can be done in 2.5cu, but people that I deemed more reliable, like Jacob Fuller, said closer to 3.5cu. Seems to me that if you were going for the cone area of a 15" with 8" subs, and you were going to dedicate 3.5cu to it, you might as well get a 15", or even a pair of 10's or 12's. The Alpines however you can port 4 of them in about 2.5-2.8cu. Four 8's is a very popular configuration for an under seat application in trucks because of the height.

I still submit that 4 8's ported in 2.8cu with 1200 watts on them is probably a pretty good option if you don't have more than 3.0cu to work with. Unless you have experienced the frustration of trying to find efficient subs that can take 600-700 watts rms with less than a 6 inch depth, and will run ported in 1.5cu or less, you don't know. The Ti2 10's are basically that, but there aren't many other options. The 8's may not be louder than the Ti2, but it would beat most anything else. Really, my experience with the Ti2 10" is that it's a freak of nature and you'll be hard pressed to find a better sub in that price range period. I just wish I could fit two. I had a pair of Orion XTR 12's sealed with 700 watts rms on them in my last ride, and a single 10" Ti2 ported with 700 watts rms is noticeably louder. It's also better sounding, which is amazing to me, though I imagine the Elite.5 amp that pushes it has a lot to do with that.

I say that to say that if Phoenix Gold made a Ti2 8" that'd get down to at least 25hz, with an 89 or 90db sensitivity, with the same 40mm peak to peak as the rest of that series, and could take 300w+ rms for about $199 it would be a huge seller for them, and I would definitely take a hard look at owning 3 or 4 of them. It would likely hit like the Sundown and sound better to boot. There is a pretty large segment of the car audio enthusiast population that swears by 8" subs.

[vladthebad]

I want some more tantrum x 8's or 8d's plain black cone, stylish, make freaking rocking midbass.... Don't suppose anyone has a pair or four stashed away to trade, lol. Although a ti2 8 might work well too. Hell, wouldn't even have to be ti series. RS? S?

[ttocs]

nope just bought myself a pair of Ti9's but no extra 8's.

[Kirghiz]

Unfortunately they don't make a Ti2 8", at least right now. There's quite a few products I'd like to see Phoenix Gold make, including those 8's, a dual 2 ohm Elite 12, an Elite 10, and some limited edition amplifier configurations, among other things. Putting two Elite.5's under one chassis would be sick as an LE amp for example. Before you ask who'd use it, my current car audio fantasy involves two Elite.5's, so there's applications for it.

[gfunk_nz]

Just to bring this back up from over a week ago, I finally got my 4 8's running. Playing music there didn't seem to be anything missing, although I do need to maybe find some rock that has fast drums and see what they do. I was curious as to how low they were comfortably playing so put on a test disk. I have my subsonic up off the 10Hz stop, so started at 20Hz, they were moving but no real output, however at 25Hz there was some serious output, I think my planned tune of 35Hz ended up being a bit lower, it was a bit hit and miss working out exact box size due to using the wheel well.
I have it low passed at 80Hz at 12db/octave, so all in all so far I pretty impressed, there's no holes in the sound that I've found yet.
The only issue I discovered was the lid of the box which is 36mm or 1.5" thick is flexing. I really didn't expect that. I have to put my Kinetik 2000 in the front as well as I found the voltmeter starting flashing away at 10.8v playing music at full noise with the car running, I have a 140A alternator on there as well.

So overall after the short play I've had I definitely think 8's are a viable option instead of larger subs

[Kirghiz]

Just to bring this back up from over a week ago, I finally got my 4 8's running. Playing music there didn't seem to be anything missing, although I do need to maybe find some rock that has fast drums and see what they do. I was curious as to how low they were comfortably playing so put on a test disk. I have my subsonic up off the 10Hz stop, so started at 20Hz, they were moving but no real output, however at 25Hz there was some serious output, I think my planned tune of 35Hz ended up being a bit lower, it was a bit hit and miss working out exact box size due to using the wheel well.
I have it low passed at 80Hz at 12db/octave, so all in all so far I pretty impressed, there's no holes in the sound that I've found yet.
The only issue I discovered was the lid of the box which is 36mm or 1.5" thick is flexing. I really didn't expect that. I have to put my Kinetik 2000 in the front as well as I found the voltmeter starting flashing away at 10.8v playing music at full noise with the car running, I have a 140A alternator on there as well.

So overall after the short play I've had I definitely think 8's are a viable option instead of larger subs

What size box did you end up going with on four of those SA-8's? They say 3.5 cu. without the port displacement is about what four would require, and I don't have that much or I would look harder at them. Four of them tuned properly are insane though from everything I have read, seen, and heard. If I went the Sundown route, I'd probably be looking at SD's sealed.

[gfunk_nz]

Just to bring this back up from over a week ago, I finally got my 4 8's running. Playing music there didn't seem to be anything missing, although I do need to maybe find some rock that has fast drums and see what they do. I was curious as to how low they were comfortably playing so put on a test disk. I have my subsonic up off the 10Hz stop, so started at 20Hz, they were moving but no real output, however at 25Hz there was some serious output, I think my planned tune of 35Hz ended up being a bit lower, it was a bit hit and miss working out exact box size due to using the wheel well.
I have it low passed at 80Hz at 12db/octave, so all in all so far I pretty impressed, there's no holes in the sound that I've found yet.
The only issue I discovered was the lid of the box which is 36mm or 1.5" thick is flexing. I really didn't expect that. I have to put my Kinetik 2000 in the front as well as I found the voltmeter starting flashing away at 10.8v playing music at full noise with the car running, I have a 140A alternator on there as well.

So overall after the short play I've had I definitely think 8's are a viable option instead of larger subs

What size box did you end up going with on four of those SA-8's? They say 3.5 cu. without the port displacement is about what four would require, and I don't have that much or I would look harder at them. Four of them tuned properly are insane though from everything I have read, seen, and heard. If I went the Sundown route, I'd probably be looking at SD's sealed.

I have them in roughly 2.5cuft after port displacement, the subs are reverse mounted so they take up no volume.

[Kirghiz]

4 8's in 2.5 after port displacement? And they sound good? I might have to look harder at them, because I can fit about 3.4 total. I should be able to make a box like that work.

Interesting. I wonder why the Sundown fanboys put them in cavernous boxes like they do?

[gfunk_nz]

4 8's in 2.5 after port displacement? And they sound good? I might have to look harder at them, because I can fit about 3.4 total. I should be able to make a box like that work.

Interesting. I wonder why the Sundown fanboys put them in cavernous boxes like they do?

I would have liked to have gone to about 3.5 but that would have raised my boot floor so high it would have been unuseable. Don't get me wrong, the bigger boxes will definitely get the most out of them but if you are pushed for space like I was but still wanted to run 4 then they will still do a damn good job in a smaller size. The recommended range is .5 to .75ft3, I'm at about .62 per sub.
If I decide I want to run them in a comp I'll block off my port remove one sub and run a 6" aeroport in it's place. I designed this for everyday use, hence the 2500 on all four, again if I wanted it to be silly I would double the power at least and use a lot more boot.

I tried getting a video to show what they can do down low, but it was useless and didn't show crap lol.

There's a photo of the setup

[Kirghiz]

That's a pretty cool install! It's kind of hard to see the cone movement when they're inverted like that, so I figure the video was pretty useless lol.

If I were going to run 4 I'd do it off an Elite.1 at 2 ohm, so it'd be about the same power you're running. I'll have to take another look at building a box for them just for lulz. By the time I put them in the box normally I'd have about the same airspace for them as you do I figure.

[gfunk_nz]

The only part I really didn't like was the port area was way too small in my opinion

[Mr. Wild]

The grille in front of the port won't help either.