Alot of questions; wiring, porting, frequency response

[bigbang 10+ year member]

Didn't feel like starting multiple threads so here it goes, any feedback appreciated.

Wiring: I have a 93 toyota camry LE. Currently I have an optima yellowtop and zero gauge positive and ground from it going to the trunk. I also have zero gauge grounding the battery to the frame, back from when I used to ground my amplifiers to the chasis.

1. Can I just add another battery in the trunk without adding an extra ground, seeing as the battery under the hood is grounded to chasis with zero gauge?

2. When I fuse both ends of the positive wire running from the one battery under the hood to the other in the trunk, do I use the fuse rating of the alternator (around 60-90 amps, not sure what stock toyota alt is). Or do I fuse based on the max current draw of the cars starter (again, no idea), dont plan on using a battery isolator. Or do I use the combined fuse rating of all my amplifiers, 450amps (three MTX amplifiers at 150amps each).

3. My two subs are rated at 900watt RMS, and I have infinity referency component speakers front and back. Do I really need an alternator upgrade if I don't crank my stereo that often, that loud? I plan on getting a new car in a couple years, this is my final install for now...I figure most of the time I drive the car, the stock alternator can keep the batteries topped off for that seldom 20 minutes a day I drive home from work, pissed off at 3am cranking it.

Porting: My new box is about 1.75 cubes per sub after displacement ported to 25Hz. Its for a couple 10" audiobahn flame Q's, until I buy some 10" FI Q subs.

1. Whats the lowest you can port a box? Is it bad to port under Fs?

2. When a woofer manufacturer states a frequency response, say 33-900 Hz, how is this achieved? Is there a low frequency cut off inherent to the woofers design, or is it in conjunction with the box design? For instance if you had an 8" woofer with a frequency response given down to 33hz, could you tune the ported box lower than this and expect bass below their cuttoff point? Or is the woofer itself going to roll off sharply despite the box? My main curiosity is do you need larger woofers for low end extension. Besides higher sensitivity, lower Fs, more excursion, ect, can you still use small woofers and tune their box to extend as low as the big boys?

3. Alot of people on this forum talk about high SPL numbers. Who amoung the SQ crowd has tuned extremely low or has designed subs that dont drop off until 20Hz? Is the ideal sub design totally flat down to 20hz (For listening purposes), or do you prefer a roll off that sums with cabin gain for a net flat-line?

Alot of questions, figured I'd pull an all for one deal. Apreciate any comments.

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[95BlackGA 5,000+ posts]

Oops

 

[95BlackGA 5,000+ posts]

`

Didn't feel like starting multiple threads so here it goes, any feedback appreciated.
Wiring: I have a 93 toyota camry LE. Currently I have an optima yellowtop and zero gauge positive and ground from it going to the trunk. I also have zero gauge grounding the battery to the frame, back from when I used to ground my amplifiers to the chasis.

1. Can I just add another battery in the trunk without adding an extra ground, seeing as the battery under the hood is grounded to chasis with zero gauge?

Answer : No idea, I don't deal with batteries, someone will come along and help you a little better.

2. When I fuse both ends of the positive wire running from the one battery under the hood to the other in the trunk, do I use the fuse rating of the alternator (around 60-90 amps, not sure what stock toyota alt is). Or do I fuse based on the max current draw of the cars starter (again, no idea), dont plan on using a battery isolator. Or do I use the combined fuse rating of all my amplifiers, 450amps (three MTX amplifiers at 150amps each).

Answer : What amplifiers are you running that are drawing 450AMPS combined? You use the fuse size that is rated for the WIRE, and WIRE only.

3. My two subs are rated at 900watt RMS, and I have infinity referency component speakers front and back. Do I really need an alternator upgrade if I don't crank my stereo that often, that loud? I plan on getting a new car in a couple years, this is my final install for now...I figure most of the time I drive the car, the stock alternator can keep the batteries topped off for that seldom 20 minutes a day I drive home from work, pissed off at 3am cranking it.

Answer : With your amps drawing 450AMPS MAX, I'd say yes.

Porting: My new box is about 1.75 cubes per sub after displacement ported to 25Hz. Its for a couple 10" audiobahn flame Q's, until I buy some 10" FI Q subs.

Why is the box tuned so low? Most of the applications that boxes like these are used for are HT (Home Theatre) setups.

1. Whats the lowest you can port a box? Is it bad to port under Fs?

Answer : The lowest a box would be tuned to I would say is an infinite number, worthless, yes. Anything under 20Hz isn't audible to the human ear.

2. When a woofer manufacturer states a frequency response, say 33-900 Hz, how is this achieved? Is there a low frequency cut off inherent to the woofers design, or is it in conjunction with the box design? For instance if you had an 8" woofer with a frequency response given down to 33hz, could you tune the ported box lower than this and expect bass below their cuttoff point? Or is the woofer itself going to roll off sharply despite the box? My main curiosity is do you need larger woofers for low end extension. Besides higher sensitivity, lower Fs, more excursion, ect, can you still use small woofers and tune their box to extend as low as the big boys?

Answer :Frequency response is only the frequencies that the given driver can produce. (I.e. tweeters can't produce any lower frequencies that produce bass.)

3. Alot of people on this forum talk about high SPL numbers. Who amoung the SQ crowd has tuned extremely low or has designed subs that dont drop off until 20Hz? Is the ideal sub design totally flat down to 20hz (For listening purposes), or do you prefer a roll off that sums with cabin gain for a net flat-line?

Answer : Don't know...

Alot of questions, figured I'd pull an all for one deal. Apreciate any comments.

Good luck with the others that I didn't answer. Also, don't take mine to heart, as I'd wait to see what others say and to see if they back them up.

 

[bigbang 10+ year member]

Thanks so far... My amps, two MTX 1501 D's, one MTX 1004. They will never be pushed to full power. I bought large a couple years ago so I only have to worry about upgrading speakers for the time being. With my newest setup, 1800watts RMS would go to the subs and 360watts RMS to the component speakers, safely. As long as I keep an eye on my voltage, I don't need the alternator upgrade if I keep my batteries topped off right?

 

[95BlackGA 5,000+ posts]

I'd definitely upgrade, you'd need about 145AMPS just for enough current for the amps. Since these cars are so small, and don't have the greatest stock alternator, you'd definitely want to upgrade. $200-$300 isn't a bad upgrade, and you can always keep it for later use if you sale the car.

 

[bigbang 10+ year member]

I'd definitely upgrade, you'd need about 145AMPS just for enough current for the amps. Since these cars are so small, and don't have the greatest stock alternator, you'd definitely want to upgrade. $200-$300 isn't a bad upgrade, and you can always keep it for later use if you sale the car.

Yeah, $200-300 isn't much. Is it really that cheap? I figured a few hundred plus a couple more for instalation. How much would a mechanic charge to swap one out with another, if I handle the wiring and he does the belt, pulley, mounting? How big of an alternator would I need if I ever plan on using my amps to thier full capacity? But again, its a 1993 beater, I plan on getting a toyota matrix in a couple years. Can I get by without the alternator upgrade and just wing it on a couple yellowtops and sensible use?

 

[95BlackGA 5,000+ posts]

You could probably wing it, with a couple batteries and sensible use. I have no idea how much a mechanic would cost, I always do my own vehicle's work.

 

[iamamp3pimp 5,000+ posts]

gonna ground the second batt to chassis, or it wont charge. it has to be a complete circuit. I have gotten subs to play under their low end cutoff, but they dont usually sound that good.

thats the freq response of the 10 inch Fi Q?

 

[bigbang 10+ year member]

Yeah, its too bad I'm afraid of doing it myself. I didn't exactly have a cool role model growing up who tought me how to work on cars. For me its oil change, spark plugs, break pads, the simple stuff. I would be scared shittless pulling the belt away from the old alternator, probably screw up the tension or timing, or something drastic. On the other hand, upholstery, fiberglass, carpentry, electric, these don't intimidate me. God I wish I had some cool friends who knew this sort of thing, but I get stuck with the idiot that has the supercharged pontiac grand prix and doesnt even know what a supercharger does. Or the guy that would never let anyone except a "profesional" lay a finger on his beloved chrystler sebring. These are the same people who are happy with stock speakers and consider replacing the head unit an axtavagent luxury.

 

[bigbang 10+ year member]

gonna ground the second batt to chassis, or it wont charge. it has to be a complete circuit. I have gotten subs to play under their low end cutoff, but they dont usually sound that good.
thats the freq response of the 10 inch Fi Q?

The second battery's negative would run to the first batteries negative with zero gauge, and the first battery under the hood is grounded to the frame with zero gauge. This is fine, right?

Q10

DUAL 1 | DUAL 2

Fs: 29.0 Hz | 26.2 Hz

Re: 0.70 Ohms/coil | 1.4 Ohms/coil

Qms: 4.80 | 5.10

Qes: .41 | .41

Qts: .38 | .38

Mms: 186g | 202g

Cms: 1.70mm/N | 1.70mm/N

Sd: 310cm^2 | 310cm^2

Vas: 22.3 l | 22.3 l

Spl: 82.9dB 1W/1m | 82.9dB 1W/1m

Bl: 10.4 N/A | 15.1 N/A

Xmax: 27mm

Rms: 1000W

Sealed box: .2-.6 cuft

Ported box: .5-1.2 cuft @ 28-33Hz

Sub OD: 11.000”

Cut ID: 9.250”

Mounting depth: 6.500”

Displacement: 0.12cuft

Product code: 01710

Price: $ 249.00

*shipping is included

Configure Speaker:

Ohm:

BP Power:

Quantity:

________________________________________

Q12

DUAL 1 | DUAL 2

Fs: 28.4 Hz | 27.1 Hz

Re: 0.7 Ohms/coil | 1.4 Ohms/coil

Qms: 05.39 | 5.63

Qes: .49 | .48

Qts: .45 | .44

Mms: 211g | 231g

Cms: 0.15mm/N | 0.15mm/N

Sd: 481cm^2 | 481cm^2

Vas: 48.3 l | 48.3 l

Spl: 85.4dB 1W/1m | 84.8dB 1W/1m

Bl: 10.4 N/A | 15.1 N/A

Xmax: 27mm

Rms: 1000W

Sealed box: .8-1.5 cuft

Ported box: 1.8-2.5 cuft @ 28-33Hz

Sub OD: 12.500”

Cut ID: 11.125”

Mounting depth: 7.000”

Displacement: 0.16cuft

Product code: 01712

Price: $ 259.00

*shipping is included

Configure Speaker:

Ohm:

BP Power:

Quantity:

________________________________________

Q15

DUAL 1 | DUAL 2

Fs: 25.9 Hz | 24.9 Hz

Re: 0.7 Ohms/coil | 1.4 Ohms/coil

Qms: 5.64 | 5.72

Qes: .54 | .54

Qts: .49 | .49

Mms: 257g | 279g

Cms: 0.15mm/N | 0.15mm/N

Sd: 810cm^2 | 810cm^2

Vas: 135 l | 135 l

Spl: 88.2dB 1W/1m | 87.7dB 1W/1m

Bl: 10.4 N/A | 15.1 N/A

Xmax: 27mm

Rms: 1000W

Sealed box: 2-2.6 cuft

Ported box: 2.8-4 cuft @ 28-33Hz

Sub OD: 15.625”

Cut ID: 14.125”

Mounting depth: 8.500”

Displacement: 0.19cuft

Product code: 01715

Price: $ 279.00

*shipping is included

Configure Speaker:

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BP Power:

Quantity:

________________________________________

Q18

DUAL 1 | DUAL 2

Fs: 24.5 Hz | 23.8 Hz

Re: 0.7 Ohms/coil | 1.4 Ohms/coil

Qms: 5.66 | 5.73

Qes: .64 | .63

Qts: .58 | .57

Mms: 322g | 342g

Cms: 0.13mm/N | 0.13mm/N

Sd: 1210cm^2 | 1210cm^2

Vas: 268 l | 268 l

Spl: 89.7dB 1W/1m | 89.4dB 1W/1m

Bl: 10.4 N/A | 15.1 N/A

Xmax: 27mm

Rms: 1000W

Sealed box: 4-8 cuft

Ported box: 6-10 cuft @ 28Hz

Sub OD: 18.500”

Cut ID: 16.750”

Mounting depth: 10.000”

Displacement: 0.24cuft

Product code: 01718

Price: $ 309.00

*shipping is included

Configure Speaker:

Ohm:

BP Power:

Quantity:

 

[tRidiot 10+ year member]

I've run 2000+ watt systems daily off the stock alt and 1000CCA AutoZone battery in my '92 Nissan (90A alt). I get some voltage drop, but no major dimming or anything.

I'm currently running 2800 rated watts, all Class A/B.

I wouldn't spend that cash until you know you need to. Don't worry about an alt unless you're getting MAJOR voltage drop and/or your alt just gives up.