Buck Mustard

Well, the whole idea of powering my 8" Bazooka speaker with an external amp just sucks. It sounds like crap.

So, I've decided it is time to get a real sub. I'm fairly certain I want to go with either a 12" or dual 12"s. Can someone please explain the difference between running 1 12" vs 2 12"s for me please? Is it just how loud you can get? I am more interested in sound quality than SPL.

Also, initially I will be using a Kenwood KAC-626 amp - I think it is like 50x2 and is bridgable. I have been told this is a fairly decent amp and will move a single 12". Do you agree? And any chance it would work with 2 12"s? Eventually, I would upgrade the amp, but available funding prevents me from doing it all at once.

I'm thinking it would be better to go with one very good 12" rather than 2 moderate 12"s... opinions?

I've looked at various boxes and it seems that for a 3rd gen, a custom box is the only decent route. I like the look and apparent quality of Jim's boxes. Audio King has quoted me slightly lower prices to build a custom box out of 3/4" MDF. Jim, do you have any comments on your box vs an Audio King custom box? The thing is, I can see the pics on your page, but I don't know for sure what AK is planning on building...

Sorry for the many questions... thanks for the help!



------------------
'88 GTA w/ t-tops
355 TPI, TPIS airfoil, Edelbrock headers,
Flowmaster exhaust, cold air induction,
MSD 6AL ignition, ADS chip, 1.6 rockers on intake,
BMR STB, Spohn SFCs
=====
Stereo:
Panasonic CQ-DFX700U
Infinity 4x6, Alpine 6x9
Rockford-Fosgate Punch 400a4
80 watt Bazooka sub

REZN8R

In my opinion if you're more interested in SQ, then a single 12 is the way to go. It's plenty loud, takes less space and requires less power. I've got a single JL 12W6 that is simply awesome. If you strike a deal, you can get one new for about $200. As for power it sounds like that Kenwood isn't really going to do it. I guess you could limp by on it, but a good amp with at least 100 watts RMS per channel would be a better route with a single 12. Double that with 2 12's. I have no idea what Jim is charging, but if you have the ability and tools it should only cost $50-75 to make a good "no frills" carpeted box.

------------------
'91 RS 3.1
SSM SFC's
Energy Susp. Hyper-flex kit
GTA Sway bars
Clarion, Phoenix Gold, JL Audio, etc.
Quote "If you can't beat them, arrange to have them beaten."
- George Carlin

Stoopalini

A single 12" is definitely the way to go in your situation in respect to both sound quality and cost.

2 12" subs will essentialy double the surface area of the speaker, giving you +3 Db in SPL; that's it.

You might want to consider a low power JL 12" to go with that Kenwood amp you have.
A JL 12-W0 is rated somewhere around 150w or so (don't quote me, this is from memory) and If you get the 4 Ohm one, you could bridge it to the kenwood amp which whould give you around 100w to it.

In a properly sealed enclosure, it should sound very nice.

For sound quality, you want to go with a sub that has a very quick response. JL, Diamond, and IDQ are three I can think of off the top of my head that make great SQ woofers.

The other thing that will make or break a good sub setup, is the box. I would never buy a pre fab box because the box needs to be custom to the speaker you are using.
If someone said they will build me a box, but didn't ask for the speaker specs, I wouldn't let them do it. The TS paramaters of the speaker dictate the volume of the enclosure it should be in.

If you get a JL sub, their web site has recommended enclosure sizes based on the TS parameters, for sealed and ported designs. (Sealed is for quality and response; ported is for increased SLP in the lower frequencies; but tends to be boomy instead of tight)

Boxes are very easy to build if you have a jig saw. The hardest part is cutting out the speaker hole, but it really is not that bad.

Let us know what you end up doing and we can help further. I would highly recommend building your own though. The cash you save can go towards an amplifier upgrade

Thomas.

Jim85IROC

iTrader: (2)

In and of itself that's true, BUT, when you add a 2nd sub, in most cases you double the power (either feed it it's own amp or bridge the current amp) which provides an additional 3dB boost for a total of 6dB.

------------------
The IROC Homepage
<A HREF="http://www.rit.edu/~jli4307/camaro" TARGET=_blank>
View the restoration of an 85 IROC</A>
"I didn't know a bored out Ford could go so slow" -Shenandoah

Stoopalini

Good call! -- absolutely correct.
I didn't think about that option because he said something about having only one amp and a limited budget.

But, if you can afford 2 amps and 2 subs, then definitely go for it! More quality equipment is always better

Thomas.


Umm, wait a min. I was thinking and now I confused myself

If I have a SVC 4Ohm sub being run with 100 watts, and I add another sub in parallel to the same config (assuming the amp can handle the load), I have now doubled my surface area and kept the wattage the same (80-100 watts to each sub) .... right?
In this case, the output in SPL would gain 3 Db.

If I added a second sub and a second amp, then I kept my power the same (still 4 Ohm load with 100 watts to each sub) so my SPL still only increased by 3Db, right?

So to get the 6Db gain, wouldn't you have to add another sub and double the wattage on both of them? So you'd have 2 subs each getting 200w?

He already has the Kenwood amp bridged to his sub, so that's presenting a 2Ohm load to each channel. I doubt that amp can handle anything lower.

So, In order to get the 6 Db gain, he would have to either:
1. Replace the kenwood amp with 2 - 100x2 (@ 4Ohm) 2Ohm stable amps, add another sub, bridge the amps, and add one sub to each amp (apx 200 watts to each sub with 2 Ohm load on each channel)

or

2. Replace the kenwood amp with a single 100x2 (@ 4Ohm) 1 Ohm stable amp, add another woofer in parallel, and bridge them to the amp (1 Ohm load on each channel giving apx 400w total, or 200w to each woofer)

Did I get this right? Man, I need to get to lunch, my brain hurts ......

[This message has been edited by Stoopalini (edited July 18, 2001).]

Jim85IROC

iTrader: (2)

If you double your surface area and keep the same total amount of power, you get a 3dB increase. That means if you have 100 total watts pushing 2 subs, you get 3dB more output than 100 watts pushing 1 sub. The ONLY variable to change is surface area.

If you double your surface area and double your total power, you gain 6dB. Running 2 subs off 1 amp effectively doubles (or close to it) the total power.

------------------
The IROC Homepage
<A HREF="http://www.rit.edu/~jli4307/camaro" TARGET=_blank>
View the restoration of an 85 IROC</A>
"I didn't know a bored out Ford could go so slow" -Shenandoah

Mike92RS

Yeah it's total power, not power to each sub he's talking about. Another thing, the Kenwood amp would probably put out more than 100 watts bridged. If it's 50x2 (4 ohms I assume), then when you brigde it, you're dropping each channel to 2 ohms, in effect doubling the output to 100x2, or 200 watts mono. Factor in the increased THD of running at a lower impendence, and it probably puts out about 160 usable watts at 4 ohms bridged mono, which will adequatly push a highly efficient 12 just fine.

- Mike

AmorgetRS

iTrader: (6)

What if you just got a single DVC and got that 3 DBL boost buy the doubling of the power of the amp without the extra space and cost of a second sub?

BTW, I have 2 12s, so I am not knocking 2 12s at all

Jim85IROC

iTrader: (2)

If the sub could handle double the power and all other circumstances (sensitivity, etc) were equal, then that would be a viable option.

------------------
The IROC Homepage
<A HREF="http://www.rit.edu/~jli4307/camaro" TARGET=_blank>
View the restoration of an 85 IROC</A>
"I didn't know a bored out Ford could go so slow" -Shenandoah

Stoopalini

From what you are saying, I can get a 3 DB gain by adding a sub to any configuration.

So, I'll get more Db output from 100 watts pushing 6 subs (that's apx 16.6w a piece) then I would from 100 watts pushing one sub?
If that's true, then I could add 3 more 12" subs, for a total of 4, and get a huge Db gain with only 25w to each sub.

I do know that when you start paralleling speakers together and lowering the impedence of the load, the amp starts putting out more wattage. That will increase your SPL,
but I didn't think that 2 speakers with 100 watts between them would be louder than one speaker with 100 watts to itself.

Now, with a DVC sub, you can parallel the coils, which lowers the impedence, upping the wattage; but keeps the surface area the same, therefore upping the SPL by mere power alone.

When you start talking about the THD of a speaker that only produces 80Hz frequencies and below being affected by the impedence, isn't it kind of pointless?
Can you really hear the difference in THD between a 4 Ohm load and a 2 or 1 Ohm load on a subwoofer?
I know with midrange and highs it is very auditable, but I've never heard a difference in a subwoofer. (maybe my hearing limitation? although I do have a very good hearing range......)

Thomas.

BTW: Good thread! Lot's of good info in here on understanding sub's

Jim85IROC

iTrader: (2)

Surface area is the main reason why a 12" sub has a higher sensitivity rating than an otherwise equal 10". Look at any brand of subs, and the bigger they are, the better the sensitivity rating is.

------------------
The IROC Homepage
<A HREF="http://www.rit.edu/~jli4307/camaro" TARGET=_blank>
View the restoration of an 85 IROC</A>
"I didn't know a bored out Ford could go so slow" -Shenandoah

REZN8R

About the THD of a sub; I've heard that when you run subs at a lower impedance, the damping factor of your amp is actually decreased. So from what I understand if you run a DVC sub with voice coils in parallel at say 2 ohms bridged then your amp only has one fourth the control it would have had if the voice coils were in series (8 ohms). So really it's not the speaker getting worse but the amps ability to effectively control the speaker. Is this correct or bogus? I'm just going from what I've heard. I know from experience I've ran a single 15" DVC both at 8 ohms bridged and 2 ohms bridged. Although the 2 ohm mode was getting a lot more raw power and was ultimately much louder, it sounded like total crap!

Pukka

One speaker can only produce mono sound.
Two speakers can produce stereo sound.

If what you are looking for is sound quality, then 2 is definitely better than one. If you want raw power, then either one large sub or as many smaller subs as you can fit is what you need. Your amp should be good enough for quality sound, just not at very high volume.

My setup is in my sig.....and there was a VERY noticeable difference when one of my subs cut out due to a loose speaker wire.

------------------
92 Camaro RS, LO3, 5-spd, T-tops

Performance:
K&N Open Air Filter, Edelbrock performer TBI intake, Fastchip Prom, Timing +4 degrees, Centerforce clutch, Xact 8mm wires, SLP 1 3/4" Headers (coated), Flowmaster Catback Exhaust, Z28 Grille w/aftmkt fog lamps, MacEwen white-face guages
Electronics:
Alpine 8030 Alarm System, Valentine One Radar Detector (How did I ever drive without one?), Pioneer DEH 7450 Head Unit w/6-pack CD changer, Pioneer DEQ 7600 Sound Processor, 2 Kenwood KAC-846 Amps powering 2 12" Pro Red subs, 2 Pioneer 6x9 and 2 MTX 4x6 speakers.
NEXT UP: TBI mods, 3.42 gears w/Torsen posi

REZN8R

Stereo with subwoofers? Hmmmmm....

AmorgetRS

iTrader: (6)

There is no reason to run subwoofers in stereo. Your ear has massive trouble telling where low sounds come from anyway, and it was posted somewhere on here that at some point it is impossible for the ear to tell.
What good is stereo if your ears can't even tell where they are coming from?

Stoopalini

I agree that the sub definitely needs a signal from both the right and the left channels, that's why I bridged my single 12".
Most people who run a single sub will have it bridged to an amp that has a stereo signal feeding it; therefore it plays both the right and left channels

When you're talking about frequencies down below 80Hz, they are considered to be uni-directional ..... meaning the human brain (ear) cannot tell direction in frequencies that low.
If you can hear a 50Hz tone, and tell where it's coming from, then you're really hearing a resonance (sp?) frequency of that 50Hz tone due to the enclosure, or interior shape, or some other variable.
Many competition systems will use devices like audiocontrol's EQTs to control this effect; and when it's setup correctly, sounds pretty awesome!

Sub frequescies usually don't differ between the right and left channels, but I'm sure there are a few tunes out there where the bass frequencies are different.

So, to clarify, 2 subs are not needed to achieve a proper stereo image. As a matter of fact, most high end (home) theater setups that have multiple subwoofers, have them stacked on top of each other due to optimal placement issues and also to avoid cancelations.

Thomas.

PS: Have we drifted off this topic yet :P

BigL350

If you're budget limited, I'd go for one high quality sub over two lower model subs. I've been impressed with the sound quality of MTX and Rockford subs. I'm not too crazy about JL audio. Some people swear by them, but they sound sloppy to me. Don't go by what the sub sounds like in the showroom. It'll sound totally different in your car, so try to find someone else with a 3rd gen and a subwoofer setup and see if you can take a listen. Make sure you really know what you're doing if you build your own box. If not, take it to a pro. A poorly built box will make even the best sub sound like crap. HTH