So normally I just use small 6" bass cannons or at most an 8" sub in a small box stuffed up inside the passenger foot well. However I got an offer from an ex Fiero Stereo nut. He had a custom Fiero sub box that was fiberglassed and shaped to fit the entire passenger side foot well and sits flush even with the bottom of the dashboard. Its not HUGE airspace but is made for a 12" sub. Now 12's are not normally something I fiddle with as I leave those to the competition guys and Rice Burners. However with my new 4.9 car being so modified already. I decided why not have a little extra boom. We have a family car now and 2 kids so its not like I'll be taking the wife out in the Fiero much anymore.

My questions are. Its a 12" rated for 1000w "PEAK" 500w RMS continuous. My Current Kicker Amp behind the passenger seat is 300w RMS 500w peak. I know under driving a speaker is almost as bad as overdriving one, but will that amp be enough to be safe? If not, what should I look for in a new amp. My amp is Old School probably been using it for the better part of 10 years. I have thought about upgrading it, but its one of those, "if it ain't broke don't fix it" type of deals. My head unit has 5 channel pre-outs 1 for the sub and 2 sets for the front and rear, however I just use the sub and run head unit power to the dash and pillar speakers, as I don't need them to do anything more than mids and tweets. I have 2 dedicated tweets in the dash pointing at the driver and passenger and good quality 4x10 dash speakers and good pillar speakers. I can't remember the brand off the top of my head. JVC IIRC.

The box is a sealed box and not a ported box, would I be better off adding a port to it.

Should I add Poly fill to the box, I am not looking for the hard BANG punchy bass I am looking more for the low tones that my 8" subs and Cannons could not produce?

Any suggestions from the Stereo guys are welcome.

Here are some pics of the new sub. I don't have pics of the enclosure, as I have not gone and picked it up yet.

I put an SD card on the front as a size reference.












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857GT Part 85GT Part 87GT Part Caddy, 93 Eldorado 4.9, 5spd Dual O2 Custom Chip, Custom Exhaust. MSD Everything Now with Nitrous. Capt Fiero --- My Over View Cadero Pics Yellow 88GT 5spd Full Poly Suspension, Lowered 1/2" in front, Corner Carver.

[This message has been edited by Capt Fiero (edited 12-15-2012).]

That "under driving a speaker will kill it" is a load of crap. See http://www.avsforum.com/t/1...-and-clipping-a-myth Or, spend a little bit of time learning about basic electrical theory, speaker construction, and how a speaker works, and it will make more sense why it's a complete load of bull droppings. Same with people thinking a capacitor is absolutely needed for big systems (it's actually a complete waste of money), or that the size of your battery affects amplifier performance.

I've run my Polk 300W RMS subs in my cars for years on a 100W amp without zero ill effects, more often than not at near full outputs. I've got a 1000W RMS sub sitting in my den running on a 50W RMS amp as well, for years, without an issue. That said, some of the bigger subs need more power to get satisfactory performance out of them, but you won't hurt it without the wattage. The short of it is that there are only two ways to kill a speaker - mechanical and thermal. Mechanically by over excursion (physically moving the speaker beyond it's physical limits), or thermally by overheating the voice coil which can happen with excessive power or insufficient cooling.

quote Originally posted by Capt Fiero: Now 12's are not normally something I fiddle with as I leave those to the ... ~ ...Rice Burners.

Comments like this really aren't neccesary. I have a 10" 1800W sub in my car and I don't appreciate that outlook being placed on me.

Thanks.

quote Originally posted by urbex: That "under driving a speaker will kill it" is a load of crap.

I don't buy that. The paperwork with my Alpine sub very clearly states that it has a Minimum power input level and I would imagine that there is a reason for it.

They also very clearly warn against clipping and the damage it can cause.
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[This message has been edited by TheRealShadowX (edited 12-15-2012).]

I've been told by numerous people that underdriving a speaker could "blow" it faster than overdriving it. I've had stereo sales / install people tell me this. I had the manager of a musical instrument store tell me this when I bought a PA system, and it's all over audiophile websites. If you're not going to push the speaker, then it won't matter as much, but who puts a speaker like this in their car and doesn't push it at all?

**EDIT** Just adding to clarify that underdriving creates distortion, which distortion is what causes damage to speakers. This is what was explained to me.

[This message has been edited by mptighe (edited 12-15-2012).]

In reality it all depends on just how loud you will be listening to your music. Under driving a speaker, causing the amp to power it with more of the peak wattage results in clipping which can blow your speaker. However, that being said, subs are rated just like other speakers. With 1 watt of input power at 1 meter that sub produces 90 db (according to one source I saw another said 91.9 but I'm unsure if the sub you have is single or dual voice coil but it appears to be single), at 2 watts add another 3 db, 4 watts 3 more, 8 watts another 3, 16 +3, 32 you guessed it 3 more and at 64 another 3, so by the time you get to 64 watts of power your going to be nearing 108 db range of output plus any boost gained from the acoustics of the car. If your not going to be listening to the stereo much past 110 db, the amp you have will be fine as you won't have exceeded it's RMS power rating to get there, granted on heavy bass notes it will work it's way into the peak wattage area of the amps delivery, but as long as it's short bursts it won't be a problem. So in essence it all depends on just how loud you will be listening to the music. If your not competing but just using it for casual listening and not planning to be heard 2 blocks away you should be fine.

[This message has been edited by Khw (edited 12-16-2012).]

I just have a few things to add to all of this. From personal experience, underdriving a speaker will cause it damage if you like your music loud. I have a 15" Rockford Fosgate and a 10" Polk MM in my Fiero. I've done all the research on installing audio in a Fiero and the molded footwell sub is a great idea. Back to my things to add:

1. That 12 has a huge driver. If your box already doesn't have a whole lot of air space, that speaker itself will take up most of it. Adding poly fill can and will make the box seem as it has more internal air space (as you probably know) in a sealed enclosure, but I won't recommend it for a ported one. Polyfil does remove a lot of the punchy bang and does make the sub produce a more rounded resonant frequency. (Ps: 1lb of poly fill is recommended for every 1cu ft of air space your box has)

2. Ported boxes work so well because they are tuned, similar to an instrument. If you want to add a port, use a port calculator online to help you determine the diameter and length of the port. (35hz is a pretty common frequency to set it to when building a box)

3. A lower profile 12" sub would give you more internal air volume, which could sound better than that big boy in the provided smaller space.

4. Amp.... I have used both class A/B amps, and class D mono block amps. I prefer the latter. Mono block amps seem to produce better bass notes, clearer bass, and more reliable bass. If you don't want to break the bank, I believe the best amp I have ever owned is my Hifonics 1000.1D. 475 watts RMS @ 4ohms. Capable of 1000 watts rms at 1 ohm (This is all continuous power). I have convinced 3 of my friends now to buy the amp and they love it. It's being used for my current setup, a 12" kicker setup, and my friend's DVC 15" Fosgate P3. The amp is ~$129.99.

http://www.sonicelectronix....6YnrQCFWrZQgodSUYA9g

Best of luck to you with the 4.9 and FOY. I've been following your thread with great interest. If you have any more specific questions, ill always answer a PM. Check out a video of my "Riceburner" setup (Haha) (another quick note, the song I used has profanity. )

[This message has been edited by mitchjl22 (edited 12-16-2012).]

In all honestly the sub is more of an early mid life crises thing. (in the later half of my 30's) I rarely turn the stereo up that much. 1/2 the time its on an AM station listening to the news, but all that said there are times that I am out having fun and I feel like listening to some music and a really good 80's song comes on that reminds me of when I was 16 growing up, and I want to crank the stereo drop to gears and plant my foot to the floor, I'd like to be able to turn the stereo up, feel the bass and not have it sound like I am rattling tin cans and crunching tin foil in my ears. I have a bunch of vintage stereo gear that I might pull out of moth balls like a powered / active crossover and second small 100w amp and 3rd small 120w amp that I might setup for front speakers and pillar speakers. Unless its pointless to run an amp to boost the signal when I am running a crossover just to dim down the bass on the midrange and tweets? My sub amp has a really nice built in crossover and my head unit has a built in crossover that is so complex I am going to have to take it to a Stereo guy just to have him tune it for me. (JVC-HDR71BT)

So in short, yes it will be cranked every now and again, but mostly just left at a normal listening volume. With most of the "cranked time" being in the first few weeks I have it installed until the coolness of it wears off.

As to the underdriving / overdriving thing, I can see both sides of the argument and frankly have never understood it, if I listen to the stereo at say 1/2 volume all the time, and never max out the amp won't that be the same as someone with a 1000w amp listening to it at 1/4 volume? I could understand if I was cranking my amp to the max all the time so much that it was tossing it into thermal protection, but for day to day use, I should be fine?

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857GT Part 85GT Part 87GT Part Caddy, 93 Eldorado 4.9, 5spd Dual O2 Custom Chip, Custom Exhaust. MSD Everything Now with Nitrous. Capt Fiero --- My Over View Cadero Pics Yellow 88GT 5spd Full Poly Suspension, Lowered 1/2" in front, Corner Carver.

quote Originally posted by mitchjl22: 4. Amp.... I have used both class A/B amps, and class D mono block amps. I prefer the latter. Mono block amps seem to produce better bass notes, clearer bass, and more reliable bass. If you don't want to break the bank, I believe the best amp I have ever owned is my Hifonics 1000.1D. 475 watts RMS @ 4ohms. Capable of 1000 watts rms at 1 ohm (This is all continuous power). I have convinced 3 of my friends now to buy the amp and they love it. It's being used for my current setup, a 12" kicker setup, and my friend's DVC 15" Fosgate P3. The amp is ~$129.99.

Actually if you look at the specs of class D amplifiers you will find they tend to have higher harmonic distortion ratings versus class AB. Class AB are usually in the .05 range and class D are usually in the .5 range. So a class D is going to produce more distortion then a class AB. Where the advantage is is in efficency. A class D is around 20 to 40% more efficent than a class AB so it takes less power to create the wattage a class D delivers. If you search class D under amplifiers on E-bay you will find 90%+ of them are monoblocks for subs. The reason being is that the distortion, while never good, isn't as critical at the lower frequencies and less noticeable tot he human ear. Class D for mid and high use is rare because the distortion becomes much more noticeable. Eventually I'm sure class D will be improved and they will become more common outside of monoblocks, but for now they really are only good for subs. The other thing to consider, even though with the lower cost of amplifiers now, is cost/ease of repair if you burn the amp up. I can repair class AB amps all day long, but class D are much harder to repair. It's not as simple as just getting another IRFZ10 mosfet and soldering it in. You have to take into account the values of the components in the circuit with it and you must match the values witht he one you install. Meaning, a mosfet has ratings, but those ratings can be off by a certain amount and still pass QC. If that Mosfet is off by to much then the class D won't work correctly, so yo have to check the values of the specific Mosfet, not what the ratings say, but actually test the Mosfet itself to make sure it is within the tighter specs class D amps require. Granted as I said ith the cost of amps now, people will tend to just replace the amp, but for me I'd rather have a class AB amplifier I could repair for $20.00 if I blow it. I have 2 class AB Diamond Audio 600W monoblock amps out in my garage that will be installed in my next car for my subs. I bought them for $40.00 each blown and repaired them for less then $20.00 each. Anywho, class D is efficent and good for subs so I wouldn't say don't get one, just be aware of their failings also just like you should with any other class of amplifier. It's easy to turn around and say while a class AB has less distortion it's not near as efficent as a class D. So basically it boils down again to personal preference of what you want.

Like a poster said above, it really all comes down to distortion. If you set the gains right on the amp and don't turn the gain all the way up to max just to try to get the max potential out of the sub, you will be totally fine. It also goes the same way in reverse. If you're over powering a sub, you have to turn the amp settings down to reduce all that distortion you'd get from powering a 500 watt sub with a 1000 watt amp. If you're listening to it and you hear buzzing in addition to the bass it's not set up correctly. A woofer is designed to make bass not any other noise. For example, I have my 10" hooked in only right now. The amp provides 475 watts rms. the sub wants 350 rms. I always have to turn down the setting on my head unit from +15 to +11 when I take the 15" Fosgate out because my amp gives it to much power and its distorting the sub. It's next to my ear, so it's really easy to tell when it's clipping. In short, you'll be totally fine, your 300 watt amp will power your 12. Just make sure it sounds good to your ear. It looks like you know what you're doing.

quote Originally posted by Capt Fiero: As to the underdriving / overdriving thing, I can see both sides of the argument and frankly have never understood it, if I listen to the stereo at say 1/2 volume all the time, and never max out the amp won't that be the same as someone with a 1000w amp listening to it at 1/4 volume? I could understand if I was cranking my amp to the max all the time so much that it was tossing it into thermal protection, but for day to day use, I should be fine?

Yes for day to day use you should be fine. In reality the 1000 watt amps used by people probably rarely sees use past 500 watts. I mean honestly by the time you get to 500 watts being pushed into a sub your up in the 120 db range if not more and rarely would any person normally listen to their music at that volume. I've been in a competition car that reached up into 126 db ranger using Orion 280 GX's to push the subs. That worked out to about 300 watts rms when bridged mono for each of the two 10" Punch Pro he used. The Orion 280 GX required a external bridging module as at that time Orion didn't have internal bridging. At 126 db, if you looked at your passenger and spoke to them in a normal voice, all they'd see is your lips moving. They would not be able to hear a word you said, even if you raised your voice. So unless your planning to listen to your music that loud you will be fine and if you do listen to it that loud, please limit your exposure because... That's loud enough to damage your hearing.

[This message has been edited by Khw (edited 12-16-2012).]

Thank You Everyone for the replies, I've heard the term Monoblock amps used by some of the Fiero Stereo guys before but honestly didn't know what they meant aside from it was for Big Boom systems. We do have one guy in the club that Is still (for the time being) a huge Stereo guy, as far as I know he has the loudest Fiero Stereo install on the planet. I don't remember what the last DB Drag Race result was but and I may be wrong it was near 150db. However he has not been at a meeting in close to a year and only seen him at a local show back in June. I may give him a call when its time to work on the tuning of the setup. However I'll be small beans compared to his setup. He actually cut the foot well in the passenger side area, removed the heater core and related parts, so he could use the entire front compartment as the enclosure for a solobaric (sp) sub then put 6 more subs across the back window and center console.

I am glad to hear that I'll be fine to use my current amp for now and I'll keep my eyes open for a good deal on something with more punch. Oh and Thank You for the clarification on the poly fill. I'll make sure to grab a bunch and toss it into the box. I'll skip the port idea for now as it sounds like I won't need it for what I want.

Something just dawned on me, LOL. My amp usually sits behind the passenger seat with an 8g power wire going through the firewall to the battery as its right there, nice and easy, then grounding everything to a seat bolt. My new engine setup I moved the battery to the front of the car. I am going to have to redesign my wiring. Oh well its about as good time as any to finally dig out that power distribution block and mount it someplace. I guess putting the amps in the front compartment would be easy, but I really don't like the idea of them up there with the fumes from the battery and our wide range in climate here, (we can be summer HOT and Below Freezing at night with high humidity would probably play hell with electronics)

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857GT Part 85GT Part 87GT Part Caddy, 93 Eldorado 4.9, 5spd Dual O2 Custom Chip, Custom Exhaust. MSD Everything Now with Nitrous. Capt Fiero --- My Over View Cadero Pics Yellow 88GT 5spd Full Poly Suspension, Lowered 1/2" in front, Corner Carver.

First off I had a Lanzar 15 same model it's pretty cheesy, I would buy something different I bought it new for $50... But it's not that your underdriving the sub it's your maxing out the amp big time, it will over heat, cut out etc... Not fun.

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I know the Lanzar is a cheaper brand, however after reading the reviews on it from several sites they all claim its a really good bang for the buck. Not from the site, but I think its kinda like the Fiero of subs. It may not be as fast as a similar price fox body mustang in a drag race, but its a whole lot cheaper than an old Ferrari. To be honest I'd be hard pressed to tell the difference between a 500 sub and a 50 sub so long as its better than my current 29.99 Bass Cannon or my old ADS A8S sub. The ADS was top of the line back in the day. Man that sucker would pound. However years of DB Drag races and Cranked to the max on the club cruises left me with ringing ears and a speaker cone that was starter to get loose.

So I did some searching for Class D amps and looking at the specs, it was a little disturbing how miss represented the ratings are now a days. In order to get 500w at 4ohms RMS you had to look for a minimum of an advertised 1500w on the Name Brand amps and 2000w on the Cheaper Brand Amps. I came across this one and thought it was kinda cool. Even if it does not produce 1/2 of the specs it says, it should be good as a throw away amp when it burns up. Assuming it does not blow up the first time I use it, it seems like a really good deal.

Talk about bang for your buck, but I am kinda worried about quality for that price, wonder if it would blow up the first time I cranked it up. (amp blowing up, not the sub)

2400w peak, 650w RMS for 80 bucks.

http://www.ebay.ca/itm/NEW-...&hash=item3f18ec5160

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857GT Part 85GT Part 87GT Part Caddy, 93 Eldorado 4.9, 5spd Dual O2 Custom Chip, Custom Exhaust. MSD Everything Now with Nitrous. Capt Fiero --- My Over View Cadero Pics Yellow 88GT 5spd Full Poly Suspension, Lowered 1/2" in front, Corner Carver.

Right now im running a JL 13tw5 with a under rated amp and have no issues with blown subs. Even if I do blow the thing up it has a warranty. In all honesty a little Dual brand amp will push that thing just fine. Hell, I have a rockford t2001bd collecting dust because I dont want it to get stolen, thats one nice thing about cheap audio, if it gets stolen then youre not out much. You know the guy shaking you house windows at 1am? Chances are he has a ported box, you know the guy who has a really clean sounding system? Chances are he has a sealed box. Poly fill will make the sub think its in a bigger box but the driver on that thing is huge so you're already hard pressed on finding the amount of cubes it needs to function properly. If you're looking for a good clean bass that will impress bigger is not always better, its all about acoustics and tuning. If I were to start over again I would have never run a 12 but rather a well tuned sundown 8 inch woofer.

quote Originally posted by Capt Fiero: I know the Lanzar is a cheaper brand, however after reading the reviews on it from several sites they all claim its a really good bang for the buck.

I looked at the manual/specs for that thing. Download it here:
http://www.lanzar.com/sku/M...sure-4-Ohm-Subwoofer

To get proper sound from it (down to 35 Hz), you need a properly designed 3.5 cubic foot box (after volume of sub is subtracted).
That's going to be the size of a bar fridge. You'd be better off getting a sub designed for a 1 cu. ft. sealed box - about what fits in the footwell.

Look at the Eminence Eminator and Pioneer specs here:
http://www.parts-express.co...24;498|3935;627|1727


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3.4L Supercharged 87 GT and Super Duty 4 Indy #163

[This message has been edited by fierosound (edited 12-16-2012).]

Yep Antuzzi I can't believe how cheap car audio has gotten 15 years ago, something like this would have been a small fortune. Well Fierosound can attest how expensive it was, as he has some of the most high dollar parts going, however his stuff is probably 15 years old and still functions like the day it was bought, most of the modern stuff if you get a year of use, you are doing pretty good.

Fierosound, thanks for looking that stuff up for me, however I have already downloaded and read it all. I know this won't be optimal by any standards, but its what I have and I am going to try it out. I was going to run a 10 speaker system in the car something similar to what you have in yours, but gave up on 4 of the speakers in favor of nice Mr. Mikes Red / Black leather seats. I figure with the dedicated Tweets in the dash plus the 3 way 4x10's in the dash and 2 way speakers in the pillars I should have my mids and highs covered, and even if the bass is not perfect my rather un-tuned ears won't notice it too bad. Here is an odd question that I have wanted to ask you for 10 years. Your setup IIRC had a center channel, how did you pull that off? Is it bridged from the left / right, or do you actually have some sort of 5.1 amp in the car. I can't see that working with radio, but maybe you have some sort of dedicated audio source for sql stuff? Side note would I be better off going WAY big on the amp or would it be a waste, I came across a few amps ranging from 4000-5000w peak, 2000w RMS that were in my price range. LOL, found one that was 13,000w too but was also 20x the price and required near house current to power it.

I was thinking that maybe going with 2000w RMS would be good, so I could upgrade the speaker later, but it may be useless to even think about upgrading if I will never have the airspace for it and I refuse to put anything behind the seat that's more than 2" thick.

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857GT Part 85GT Part 87GT Part Caddy, 93 Eldorado 4.9, 5spd Dual O2 Custom Chip, Custom Exhaust. MSD Everything Now with Nitrous. Capt Fiero --- My Over View Cadero Pics Yellow 88GT 5spd Full Poly Suspension, Lowered 1/2" in front, Corner Carver.

quote Originally posted by Capt Fiero: ... Your setup IIRC had a center channel, how did you pull that off? Is it bridged from the left / right, or do you actually have some sort of 5.1 amp in the car.

I'm using the simplest setup which is "bridged stereo" (or mixed mono). It doesn't required any fancy processing or amp.
I don't recall the value of the resistor I used. It would vary with your setup/speaker anyway (trial and error).
Start with nothing. IF it seems like ALL sound is coming from center, use a 4 ohm resistor inline.
(I have my center channel wiring accessible in gauge pod - so you can make changes without pulling dash again)



See here on bridged stereo: http://www.termpro.com/asp/pubs.asp?ID=115

BASIC Car Audio for everyone: http://www.bcae1.com/

[This message has been edited by fierosound (edited 12-16-2012).]

Thank You Fierosound.

Now I have good news and I have bad news.

Shall we start with the bad news. My Kicker Impulse amp is not as powerful as I thought. I had long since forgotten the model number so I went out and checked. Then I came in and goggled the specs.
Bare in mind this has ran flawlessly for 10+ years and powered everything from 6" base cannons to 8" ADS A8S Sub for years and even ran a really nice Square Sub that he needed me to transport for him and I could not help but hook it up and try it out. Sounded amazing, to me.

Good News is I'll be getting a new amp really freaking soon. I'll have to wait till after Christmas or I'll feel guilty buying myself a new toy, instead of one of my daughters an extra toy.


Here are the RMS Specs on the amp.

Its not even 300w

Kicker Impulse 652xi Specs:

Power at 14.4V:-----------------------------------Power at 12.5V:
2 x 95W @ 4 ohms (0.085% THD)---------------2 x 65W @ 4 ohms (0.085% THD)
2 x 130W @ 2 ohms (0.2% THD)----------------2 x 90W @ 2 ohms (0.2% THD)
1 x 260W @ 4 ohms bridged (0.2% THD)------1 x 190W @ 4 ohms bridged (0.2% THD)


Its the first time I think I have ever seen different specs for different voltages, but I guess that would make sense more power in, more power out. I know when my alternator was going bad, I was pushing over 18v through it for a short time. I drove around with my headlights, heater and rad fan locked on until I could replace the alternator.

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857GT Part 85GT Part 87GT Part Caddy, 93 Eldorado 4.9, 5spd Dual O2 Custom Chip, Custom Exhaust. MSD Everything Now with Nitrous. Capt Fiero --- My Over View Cadero Pics Yellow 88GT 5spd Full Poly Suspension, Lowered 1/2" in front, Corner Carver.

quote Originally posted by urbex: That "under driving a speaker will kill it" is a load of crap. See http://www.avsforum.com/t/1...-and-clipping-a-myth Or, spend a little bit of time learning about basic electrical theory, speaker construction, and how a speaker works, and it will make more sense why it's a complete load of bull droppings. Same with people thinking a capacitor is absolutely needed for big systems (it's actually a complete waste of money), or that the size of your battery affects amplifier performance. I've run my Polk 300W RMS subs in my cars for years on a 100W amp without zero ill effects, more often than not at near full outputs. I've got a 1000W RMS sub sitting in my den running on a 50W RMS amp as well, for years, without an issue. That said, some of the bigger subs need more power to get satisfactory performance out of them, but you won't hurt it without the wattage. The short of it is that there are only two ways to kill a speaker - mechanical and thermal. Mechanically by over excursion (physically moving the speaker beyond it's physical limits), or thermally by overheating the voice coil which can happen with excessive power or insufficient cooling.

is..
wonder how many alt. you've killed from this, underpowering a loudspeaker will kill it.. , under drive one and then pull the coil and look at it.. , it's not a myth..

quote Originally posted by E.Furgal: is.. wonder how many alt. you've killed from this, underpowering a loudspeaker will kill it.. , under drive one and then pull the coil and look at it.. , it's not a myth..

What?

This is nonsense. The only thing under-powering a speaker will do is prevent it from accurately reproducing the full range of tones it is designed to produce, as the speaker may not be able to produce enough force and movement to produce them, without sufficient power to do so. If you aren't providing enough power to overheat the coil, or extend the cone beyond it's manufactured range, then it's not going to damage the speaker. The only way to do those two things, is to provide too much power. Installing a speaker in an enclosure that is too small, or too large, may exacerbate these potential issues, as there may not be enough air volume or movement to cool the voice coil, even with lower than designed power input.

quote Originally posted by Capt Fiero: The box is a sealed box and not a ported box, would I be better off adding a port to it. Should I add Poly fill to the box, I am not looking for the hard BANG punchy bass I am looking more for the low tones that my 8" subs and Cannons could not produce?

What is the volume of the enclosure? What is the sealed enclosure design volume for the sub? What is the ported design volume?

What 8" sub was it? What was the type/volume of the enclosure it was in? What were the specs?

If you want tight and accurate bass, stick with a sealed enclosure. If you want punchier bass, you can go with a port. But I suspect either way, the enclosure isn't large enough for the sub to work its best.

For what it's worth, I get plenty of bass out of a JL 6w0. Even the one installed in the last-gen extended cab S-10 I used to have, would rattle the cabin and seats; without being too loud outside the cab.

You don't need a huge sub to produce the bass you want. You just need the proper enclosure for a good sub, with the proper amp to power it efficiently.

And I'd leave the polyfill out. Unless the enclosure is too large for the speaker's design specs. Then a little might help. All it does is decrease air volume in the enclosure, and make the air volume occupy a sufficiently more complicated structure.

quote Originally posted by dobey: What is the volume of the enclosure? What is the sealed enclosure design volume for the sub? What is the ported design volume? What 8" sub was it? What was the type/volume of the enclosure it was in? What were the specs? If you want tight and accurate bass, stick with a sealed enclosure. If you want punchier bass, you can go with a port. But I suspect either way, the enclosure isn't large enough for the sub to work its best. For what it's worth, I get plenty of bass out of a JL 6w0. Even the one installed in the last-gen extended cab S-10 I used to have, would rattle the cabin and seats; without being too loud outside the cab. You don't need a huge sub to produce the bass you want. You just need the proper enclosure for a good sub, with the proper amp to power it efficiently. And I'd leave the polyfill out. Unless the enclosure is too large for the speaker's design specs. Then a little might help. All it does is decrease air volume in the enclosure, and make the air volume occupy a sufficiently more complicated structure.

Well I decided to go ahead and Go Big with the amp. Its better to have more power and not need it, than to need it and not have it.

4500 watts peak, 2100w RMS, from what I have read 2g minimum power cable and recommended 0g. Plus they also recommend taking power and ground directly from the battery. Which in my case is going to kinda suck, as I have a front mount battery. I have read several reviews and they do say that the amps are overrated by about 10-15% so I should expect closer to 4000w peak and 1800w RMS. Which should be more than enough to blow this sub up or at least deliver nice clean power at 1/2 load.

http://www.ebay.com/itm/NEW...me=ADME:L:OC:US:3160

Dopy I don't have the specs on the volume of the box, as frankly I get what I get, and there is no option for larger. I know its going to be too small for the sub, but I'll deal with it as best as I can. I am not looking for the Tight Bass, but the long thunder deep tones that my 8" simply could not produce the 8" was an ADS A8S Competition Sub and was one of the best 8's on the market when it was made. It too lasted nearly 10 years of abuse which is a testimate to its quality. It was in IIRC a 1cu ft box.

I have decided after reading everyones posts and talking to them, that I will not be using a port and I will be using about 1 pound of poly fill to make it sound the way I want. Now that I have the amp on the way, the sub is here I am just waiting on my car to be done and I can start wiring things up. I'll post pics when I have the enclosure here just so people can try and help me estimate the size.

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[This message has been edited by Capt Fiero (edited 12-18-2012).]

Ack, I ran into a bit of an issue today, I have no idea what size speaker wire to use. I grabbed a roll of 12g but am worried that won't be big enough. Anyone want to offer a suggestion.

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857GT Part 85GT Part 87GT Part Caddy, 93 Eldorado 4.9, 5spd Dual O2 Custom Chip, Custom Exhaust. MSD Everything Now with Nitrous. Capt Fiero --- My Over View Cadero Pics Yellow 88GT 5spd Full Poly Suspension, Lowered 1/2" in front, Corner Carver.

8g is usually sufficient.

Excuse the quality, but I snagged a few pics from home regarding the clipping argument.





Read "What is not covered" Point #2 here.

[This message has been edited by TheRealShadowX (edited 12-21-2012).]

Not sure what the knowledge level is of those who claim that under powering a sub will not cause damage...but as a MECP Advanced certified audio installer who is studying for his Master certification I can tell you that they are WRONG! For some reason they all seem to think that you'll turn on the radio and then it will just blow. They are correct that this isn't something that will happen quickly. But as others pointed out depending on how you treat the system while it's under powered will cause the system to last longer or not. Every day I deal with customers with blown subs, and almost every time it's caused by one of two things. #1 the gain was cranked all the way up, or #2 the sub was incorrect wattage for that amp(over or under powered). So under powering a sub might allow it to last for a few years if you treat it well, but correctly powering a sub will help it last for 10 years+. Like I said, this is something I see on a daily basis as audio is my job, not a hobby.

[This message has been edited by thedude557 (edited 12-21-2012).]

quote Originally posted by thedude557: Not sure what the knowledge level is of those who claim that under powering a sub will not cause damage...but as a MECP Advanced certified audio installer who is studying for his Master certification I can tell you that they are WRONG! For some reason they all seem to think that you'll turn on the radio and then it will just blow. They are correct that this isn't something that will happen quickly. But as others pointed out depending on how you treat the system while it's under powered will cause the system to last longer or not. Every day I deal with customers with blown subs, and almost every time it's caused by one of two things. #1 the gain was cranked all the way up, or #2 the sub was incorrect wattage for that amp(over or under powered). So under powering a sub might allow it to last for a few years if you treat it well, but correctly powering a sub will help it last for 10 years+. Like I said, this is something I see on a daily basis as audio is my job, not a hobby.

Just curious, those underpowered setups, did the owner have his gain cranked to max?

Really, if a sub handles 500 watts rms and 1000 peak, and then you hook a 500 watt rms amp up to it, is that amp going to be dumping 500 watts into the sub continuosly? Answer me that. Then provide facts to back up your answer.

It will last a couple of years? Yeah, right.... I have a 350 watt RMS sub in our Mazda that's been there for a year. Before that it was in my VW for 6 years. That whole time it's run off a 150 watt RMS amp. So how does 7 years = a couple? Why has it lasted so long? Well I don't have the gain maxxed out and I don't listen to my music at a very high volume. So my sub never see's the amplifier going into fits trying to sustain peak output. That's what damages a amplifier if you under power it, the amplifier trying to sustain peak wattage output to push it. If you are listening responsibly, then your sub will continue to last like mine. I'll tell you what, check back in another 7 years and if it's blown by then I'll pull the sub apart and we can look at the voice coil.

I did a little search and found this from a car audio installation shop.

quote Actually, Parrots Custom Car Audio, underpowering a sub will damage it in NO way. The ONLY way you can damage a sub is by overpowering it, period. Let me explain. What Parrots Custom Car Audio was explaining was clipping. While he explained clipping correctly he made a wrong assumption. Clipping is not caused by an amp underpowering a sub. Clipping is typically caused when you turn the gain on your amp too high. Clipping can be a complicated topic but what you need to know is that clipping and underpowering are two seperate things. You CAN damage a sub by using an amp that is "underpowered" compared to the sub. Say you get a 1200w amp. If you turn up the gain too high your amp could start clipping severly. Your amp will then send the sub a clipped signal. Now a clipped signal isn't bad by itself. You can run a sub on a clipped signal all day with no problems. What the problem is is that the clipped signal is much more powerful then a regular signal. That means your 1200w amp could deliver over 2000w. That means you sub could be overpowered. So in the end, clipping isn't what damages the sub but the fact that the sub is overpowered IS why you could damage your sub. It would be VERY hard to blow that sub with an amp that is only 1200w or 900w RMS, even if it is sending a fully clipped signal. That sub can take a lot of power so I would be doubtful you could blow that sub if you tried. The only real way I could see you blow it is if you put it in a very poor enclosure that is not meant for that sub. When you amp is clipping it will sound like distortion. Most installers can hear when the amp starts to clip and make sure to set the gain correctly so it is not clipping. The only disadvantage of underpowering is loss of output. That means your sub will not give quite as much output as it would if you were using a 2000w amp. You underpower a sub everytime you turn the volume down. When you turn the volume knob down you are actually underpowering all your speakers and your sub. As you can see you don't ever blow your speakers when you do that. Bottomline: - Set the gain correctly - Use a proper enclosure If you do those things you will not blow your sub. Good Luck!!! Source(s): MDCustoms

This is what I'm saying. You do not drive a sub at it's fully rated power when you listen to it at normal listening levels. Rarely are you actually delivering the full rated power to a sub. So, make sure you set your gain properly, so when you do turn up the volume you don't cause clipping and it will last for many long long years.

Ehow.com

quote Underpowering any speaker creates risk. Whenever a subwoofer is underpowered, the temptation to crank the gain or input knob to compensate for a lack of volume is ever-present. Additionally, distortion-producing processing such as bass-boost knobs or other such controls causes distortion. Ironically, it is typically these compensatory controls that cause damage more than the lack of power.

So again, it's all in how you set up your boosts and gains. It's when someone uses a 150 watt amp on a 600 watt sub and they max out the gain and turn up the boost control that causes clipping and the damage. Set your gains properly and you will be fine.

I understand your a certified MECP installer, and while I haven't taken the test, back in the 90's I did get the MECP study guide which I still have out in the garage, I was studying to take it. So you should know that a sub is rarely driven to it's maximum ouptut and is commonly "underpowered" in normal listening.

[This message has been edited by Khw (edited 12-21-2012).]

quote Originally posted by TheRealShadowX: Excuse the quality, but I snagged a few pics from home regarding the clipping argument. Read "What is not covered" Point #2 here.

And all of those points about "clipping" are actually "do not over-drive the speaker" (which can induce distortion and clipping). Nothing to do with under-driving, or direct clipping. The clipping is merely a sign that you are over-driving the speaker. You originally stated the documentation specifically listed a "minimum input requirement" and nothing in those pictures shows that.

quote Originally posted by Khw: ... Why has it lasted so long? Well I don't have the gain maxxed out and I don't listen to my music at a very high volume. So my sub never see's the amplifier going into fits trying to sustain peak output. That's what damages a amplifier if you under power it, the amplifier trying to sustain peak wattage output to push it. If you are listening responsibly, then your sub will continue to last like mine.

I ran my OZ Audio subs (rated at 150-200 watts) with 50 watts RMS each ("peak power" means nothing) from a Denon 6-channel amplifier (6x50 watts) in stereo competitions where they crank the systems for SPL readings. I never won SPL because my gains limited the volume to prevent the subs from clipping (but I cleaned up in SQ judging )

In Sound Quality judging I was blowing away guys with a trunk full of amps/subwoofers and speakers running 1000's of watts (THEY won SPL - where distortion is ignored - volume is everything). I ran it like that for 8 years.

When I changed to the Mcintosh amplifer I doubled my sub channel power to 100 watts RMS each, and still using the same OZ Audio subs, I DO have more volume - still without clipping because my gains are adjusted properly. (to the maximum where clipping starts, then back down a bit) The Mcintosh is a 6-channel 400 watt (total power) amplifier (4x50 watts, 2x100 watts).

Keep in mind both my amplifiers produce clean RMS power with low distortion - 0.005% for the Mcintosh at FULL power on all channels. Some cheap amps have 10% distortion at maximum power and that sure isn't gonna help anything, because between the distortion and clipping you'll destroy any speaker from voice coil overheating.

That said - it's still a good idea to try to match amplifier power and speaker requirement. A cheap low efficiency sub rated at 1000 watts may not make a peep with just 20 watts RMS from even a highly rated GOOD amplifier.

The problem is, some people end up buying a cheap low quality 1000 watt amplifier to drive it. See how things can compound?

The BIG numbers don't mean anything. You'll get more and better sound from a quality 200 watt sub driven by a quality 150-200 watt RMS amplifier.

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quote Originally posted by fierosound: That said - it's still a good idea to try to match amplifier power and speaker requirement. A cheap low efficiency sub rated at 1000 watts may not make a peep with just 20 watts RMS from even a highly rated GOOD amplifier.

That said, I've run cheap (Pyramid) 500w 10" subs in a hatchback enclosure, in the trunk of the 89 Cavalier I used to drive ~14-15 years ago, and just spliced them into the factory wiring of the speakers in the rear deck. Even with that little power, it would sound pretty great for what it was. They would still move quite a bit of air, even without getting their rated power.

I even hooked them up to the factory sub amp in a previous Fiero I had, once. Had that huge box in the passenger seat. Was a bit loud, but had to have the sunroof out to fit them in, and so it didn't sound that great really.

quote Originally posted by dobey: You originally stated the documentation specifically listed a "minimum input requirement" and nothing in those pictures shows that.

You're absolutely right. For whatever strange reason, they decided to leave power specs out of the warranty info and instead put them in the instructions. Weird right?

If you really want I can also snap and post a pic of that seperate piece of info.

quote Originally posted by dobey: That said, I've run cheap (Pyramid) 500w 10" subs in a hatchback enclosure, in the trunk of the 89 Cavalier I used to drive ~14-15 years ago, and just spliced them into the factory wiring of the speakers in the rear deck. Even with that little power, it would sound pretty great for what it was. They would still move quite a bit of air, even without getting their rated power. I even hooked them up to the factory sub amp in a previous Fiero I had, once. Had that huge box in the passenger seat. Was a bit loud, but had to have the sunroof out to fit them in, and so it didn't sound that great really.

Glad it worked well enough for you.

quote Originally posted by Capt Fiero: I know under driving a speaker is almost as bad as overdriving one ...

First I will repeat the quote below, because it is almost (but not quite) 100% correct:

quote Actually, Parrots Custom Car Audio, underpowering a sub will damage it in NO way. The ONLY way you can damage a sub is by overpowering it, period. Let me explain. What Parrots Custom Car Audio was explaining was clipping. While he explained clipping correctly he made a wrong assumption. Clipping is not caused by an amp underpowering a sub. Clipping is typically caused when you turn the gain on your amp too high. Clipping can be a complicated topic but what you need to know is that clipping and underpowering are two seperate things. You CAN damage a sub by using an amp that is "underpowered" compared to the sub. Say you get a 1200w amp. If you turn up the gain too high your amp could start clipping severly. Your amp will then send the sub a clipped signal. Now a clipped signal isn't bad by itself. You can run a sub on a clipped signal all day with no problems. What the problem is is that the clipped signal is much more powerful then a regular signal. That means your 1200w amp could deliver over 2000w. That means you sub could be overpowered. So in the end, clipping isn't what damages the sub but the fact that the sub is overpowered IS why you could damage your sub. It would be VERY hard to blow that sub with an amp that is only 1200w or 900w RMS, even if it is sending a fully clipped signal. That sub can take a lot of power so I would be doubtful you could blow that sub if you tried. The only real way I could see you blow it is if you put it in a very poor enclosure that is not meant for that sub. When you amp is clipping it will sound like distortion. Most installers can hear when the amp starts to clip and make sure to set the gain correctly so it is not clipping. The only disadvantage of underpowering is loss of output. That means your sub will not give quite as much output as it would if you were using a 2000w amp. You underpower a sub everytime you turn the volume down. When you turn the volume knob down you are actually underpowering all your speakers and your sub. As you can see you don't ever blow your speakers when you do that. Bottomline: - Set the gain correctly - Use a proper enclosure If you do those things you will not blow your sub. Good Luck!!! Source(s): MDCustoms

One point, in particular, requires repeating in the context of this discussion: "Underdriving" a speaker cannot harm it. You do this every time you turn the volume down! It's also worth noting that the average power delivered to the speakers when playing music, even at very loud listening levels, is typically quite a bit less than 10 watts.

Next, my credentials. I am an engineer. Besides working summers in college designing and installing custom commercial and residential sound systems, I worked for seven years in the 1960s and 1970s as a broadcast and recording engineer, and later in the '70s my company designed and manufactured special-purpose electronic equipment, including a 100 watt-per-channel commercial audio power amplifier. (See picture below.)

There are three primary failure mechanisms related to speaker failure due to mismatched amplifiers:

1) Overdriving a speaker ... i.e. use of an amplifier producing more power than the speaker is capable of handling. The dominant failure mechanisms are either mechanical, due to the voice coil exceeding its travel limits, or electrical, due to overheating the voice coil and/or the surrounding structure.

2) Overdriving an undersized amplifier, which results in hard clipping. This is the detail in which the article above is incomplete, particularly with respect to low-frequency speakers like subwoofers. A clipped low-frequency signal suddenly contains a huge amount of its energy in the high-frequency end of the spectrum, energy that a sub (in particular) is incapable of efficiently coupling into the air. That energy has to go someplace, and that someplace can be either heat in the voice coil and/or internal shearing in the cone material (e.g. the voice coil ripping itself away from the cone).

3) Inadequate acoustic loading of the speaker. If the speaker can't transfer a significant portion of the energy it receives from the amplifier into the air, that energy has to go someplace. The usual results are the voice coil exceeding its mechanical limits or overheating the voice coil. At low frequencies the usual cause of inadequate acoustic loading is a poorly designed enclosure ... or no enclosure at all. At higher frequencies (e.g. during amplifier clipping), even an enclosure designed for proper low-frequency loading provides virtually no loading at all higher in the audio spectrum.

What to do? 1) Properly match the amplifier(s) to the speaker(s). 2) Place a properly-sized fast-acting fuse in the feed to each speaker. (Such fuses ... or fast circuit breakers ... used to be standard equipment in top-quality power amps.) Sure it's a pain to have a fuse blow now and then, but would you rather buy a new speaker or amp? 3) In case of an undersized power amplifier, place a low-pass filter between the amplifier and sub. 4) If all else fails, turn the volume down.


The prototype of my 100 watt-per-channel (RMS, continuous, into 4 ohms) stereo amplifier. It could also be configured in "bridge" mode as a 200-watt single-channel amp. It still works, 35 years later:



The massive heat sink was just something I had left over from a previous project. See https://www.fiero.nl/forum/F...ML/090611-2.html#p41 for more information.

[This message has been edited by Marvin McInnis (edited 12-22-2012).]

Marvin,

First off, you want to do all my sound stuff in my Fiero?

Second, isn't point #2 in your explanation a kind of rewording of underpowering a speaker? Is it that people have just been explaining it wrongly? My understanding is that the amps don't push the speakers as much as the speaker "pulls" the amp. If the speaker is demanding more than the amp is delivering it will overpower the amp (maybe incorrectly stated as the amp underpowering the speaker)? If this is the case, then it would be volume based wouldn't it? If this is true, the more you ask the speaker to deliver, the more it requires, and if this isn't enough it causes clipping and excessive heat and distortion, both of wihch will cause premature wear of the speaker right?

quote Originally posted by mptighe: First off, you want to do all my sound stuff in my Fiero?

First off, I don't do automotive "sound stuff" ... even in my own cars. An automobile is just about the worst acoustic environment I can imagine, and the signal-to-ambient-noise ratio is less than about 20 dB at best. So ... not just no, but HELL NO!

quote Second, isn't point #2 in your explanation a kind of rewording of underpowering a speaker? Is it that people have just been explaining it wrongly?

Maybe. But the idea of "underdriving" a speaker, which most likely originated as a marketing term, completely misrepresents the situation. A speaker rated at 100 (or 1000) watts RMS will sound just fine powered by a good-quality 10-watt amplifier as long as the amp is operated within its ratings (i.e. isn't driven into clipping). The system with the 10-watt amp won't be as loud, but otherwise it will sound just as good. In fact, at lower listening levels a 10-watt amp may actually sound better than a 1000-watt amp, because of the phenomenon of crossover distortion inherent in the push-pull output stages of some analog amp designs.

quote My understanding is that the amps don't push the speakers as much as the speaker "pulls" the amp. If the speaker is demanding more than the amp is delivering it will overpower the amp (maybe incorrectly stated as the amp underpowering the speaker)?

No. Except for resonance effects, a speaker is for all practical purposes a passive device. Some amplifiers do have a minimum load impedance (impedance ~ AC resistance) specification, though. Connect a 4-ohm speaker to an amp with a (hypothetical) minimum load impedance spec of 16 ohms, and you may be asking for trouble. But that is independent of the maximum power rating of either the speaker or the amp.

[This message has been edited by Marvin McInnis (edited 12-22-2012).]

quote Originally posted by Marvin McInnis: No. Except for resonance effects, a speaker is for all practical purposes a passive device. Some amplifiers do have a minimum load impedance (impedance ~ AC resistance) specification, though. Connect a 4-ohm speaker to an amp with a (hypothetical) minimum load impedance spec of 16 ohms, and you may be asking for trouble. But that is independent of the maximum power rating of either the speaker or the amp.

I see. This is why I'm at a disadvantage as a consumer, like many others. Thanks for the responses. I'm sure you've probably answered this before, but what arena of engineering are you in?

quote Originally posted by mptighe: ... what arena of engineering are you in?

My formal education was in the physical sciences and aeronautical engineering, but most of my working life has involved electronics, television, computers, software, computer graphics, and meteorology. Somewhat ironically, I've never worked in the aerospace industry except as a computer consultant/contractor, and along the way I've also worked as a developer/consultant in manufacturing automation and statistical quality control, industrial heat exchangers, alternative energy, defense (DOE), and biostatistics (FAA). If you master the fundamentals, you can learn the details of most narrow technical specialties as needed, although it still requires substantial effort to develop and maintain an acceptable level of competence. I still take night classes at our excellent local community college to keep my brain exercised ... everything from anthropology to welding.

[This message has been edited by Marvin McInnis (edited 12-22-2012).]

Ok now that we have gone into a huge argument over clipping vs underpowering vs overpowering, can we just agree to disagree.

My second question was speaker wire size, I bought 12g and was not sure if that was adequate and it was recommended that 8g would be better. I'll go out and buy 8g wire if we can agree that I don't need to go bigger.

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857GT Part 85GT Part 87GT Part Caddy, 93 Eldorado 4.9, 5spd Dual O2 Custom Chip, Custom Exhaust. MSD Everything Now with Nitrous. Capt Fiero --- My Over View Cadero Pics Yellow 88GT 5spd Full Poly Suspension, Lowered 1/2" in front, Corner Carver.