So how does this combination "sound" to you

[MrDHEJ]

Going in a 1999 Chevy Silverado Ex-Tended Cab

Front doors: MM6 6.5"
Side rear panel: MMC 4x6
Under rear seat: JL Audio stealthbox 12"

US Amps TU-600 driving the MM6's
US Amps USA-200X driving the MMC 4x6's
US Amps USA-1000X driving the sub

How good do you think this combination would be in terms of SQ?

Only problem i may encounter is where to put 3 amps. Only thing atm i can think of is putting the amps in a box ajacent to the sub on the floor under the rear seat.

[TrappedUnder Ice]

Nice choice in amps btw.... I wonder though...what that JL stealth box uses... cause thats a lot of power for JL subs (1000x) and hate to see you smoke em'

[Jstas]

Just pull the crap JL subs and unload them on eBay to some kid that buys into the JL hype for 3 times what they are worth and load the stealth box with subs that can handle the power.

[MrDHEJ]

LOL nice plan you got there jstats.

the specs for the sub in the stealthbox is...
the 12W3v2-D2 in a sealed, downfiring enclosure. 300 Watt power handling. Wired for 4 ohm mono.

what sub would you guys recomend?

Honestly, now i'm wondering if all this is going to be to much. the cab volume in my truck is a TON less then a car, so it's not going to need a whole lot to sound loud. and i'm just not sure i can crame 3 amps and maintain a stealth look that's clean and un-noticable.

I think there is enough room under the stealthbox to put the sub amp, but space is a premium on the other side for 2 amps. and if i put them in a box to conceal them i'm going to need suplimental cooling to circulate the air past the amps. and i don't know if stcking them on top of eachother would be a good idea.

[sntnsupermen131]

mount the amps behind the back seat under the rear window
i have a 96 gmc extended cab and thats where my amps are
and i jstas wasnt kidding about getting rid of the JL...
they make awesome stealth boxes, crappy subs
-Cody

[MrDHEJ]

sntnsupermen131, i thought of that at first, untill i looked. In my 1999 silverado there is only about 1cm of space at the top of the back seat, and about 8cm at the bottom. But once the seat is up it's about 1cm top or bottom. They did a perty good job of not wasting space back there on the later models. :/

[Jstas]

The stealth box is not going to be too much with 1 woofer. For the human ear to hear bass, it needs to be loud. The lower in frequency you go, the louder the volume needs to be to adequatly hear the bass response. That is why subs take considerably more power and space. They need teh power and displacement to play the low notes audibly enough to blend with the rest of the music being played.

The nice thing about the stealth boxes is that they are usually out of the way. If not, they have usefulness other than a speaker enclosure to them. They also match your interior so well, they blend in. Hence the name "stealh box".

As far as what speaker to recommend as a replacement, that is difficult. If you can find out some info, I'd better be able to make a recommendation. Basically, what is the internal volume of the enclosure? It is a sealed enclosure and right now, it looks like a MOMO 2124 would work best and compliment your choice of full-range drivers well.

You should be able to call JL Audio customer service or tech help line to find out the internal box volume.

[sntnsupermen131]

Originally posted by MrDHEJ
sntnsupermen131, i thought of that at first, untill i looked. In my 1999 silverado there is only about 1cm of space at the top of the back seat, and about 8cm at the bottom. But once the seat is up it's about 1cm top or bottom. They did a perty good job of not wasting space back there on the later models. :/
well thats shitty, im going to get a new model gmc in a couple years...
-Cody

[MrDHEJ]

Yeah it is, but what do you think of mounting the amps IN the bottom part of the seat? That way when you flipped the seat up you'd be able to see the amps.

[sntnsupermen131]

you could do that too, just slide a piece of wood under the lining of the seat, screw the amps in
wouldnt mount them on the floor for fear of getting kicked and breaking off terminals
-Cody

[MTXMAN]

Very nice choices on amps. just hold of on the 1000x till you decide which sub to replace the JL with so you get the right ohm load, if you get a dvc that bridges to 2ohms you'll want the 1000 instead... anybody know if an IDMax would fit in there?? i'd say go with the Diamond audio TDX's as they're my personal favorite but there's no way in hell that that magnet would fit in that box... check em out at www.diamondaudio.com they sound gorgeous...

[MrDHEJ]

MTXMAN, i have decided to go with the Polk c500.1 and c400.4 amps. I'm sure i am going to get good crisp clean sound with this combination. No it won't set DB records, but that's not what i want.

[MTXMAN]

no need to explain to me dawg, it's your car and you're the one that's gotta be happy with it. I hope it goes above and beyond your expectations :D

[MrDHEJ]

MTXMAN... I just went and looked at that sub from TDX. dam that's big! Not sure if it will fit in the stealthbox, but what is the cost of that monster?

[MrDHEJ]

sntnsupermen131:

Guess what, I think 3 amps WILL fit behind the back seat. There’s trim at both sides of the back seat, and some sort of vent with ducting. Not sure why these were put in there, but the ducting can be trimmed, and I’m not even sure the vents need to be there.

Anyway, with the seat up there’s about 3" of room, which should clear the amps. I made some cardboard replica amps in the sizes I’m trying to put back there and it should fit. I'll try and get some pictures today and show ya the plan.

The down side is unless you carry around an 18mm wrench you can't display the amps. The up side though is it retains the stealth look, and security of your investment.


MTXMAN:

Ok, as we were talking in the other thread about these amps, it's clear that the US Amps produce better SQ then the Polks. I had set my mind on the tube amp but once I looked at the regular USA-600 amp it looks like it is louder "Signal/Noise Ratio: 105dBA" AND has better SQ "THD at Rated Power: <0.006%". Vs. the TU-600 amps 100db and thd <0.05.

So why would the tube amp be better?

USA-600X
Two Channel Class AB Amplifier
Total Power Output: 600 Watts RMS
THD at Rated Power: <0.006%
Stereo Separation: >98dB
Signal/Noise Ratio: 105dBA
Frequency Response: 5Hz-50KHz
Fuse Rating: 75 Amps
Variable 24dB Low-Pass Active Crossover
Two-Ohm Stable
150 Watts x 2 into 4 Ohms
195 Watts x 2 into 3 Ohms
300 Watts x 2 into 2 Ohms
600-Watts Bridged into 4 Ohms

TU-600
Two Channel Class A Amplifier Direct Tube Input
Oversized MOSFET Power Supply
Total Power Output: 600 Watts RMS
THD at Rated Power: <0.05%
Signal/Noise Ratio: >100dBA
Frequency Response: 15Hz-50KHz +/-0dB
Fuse Rating: 60 Amps
Two-Ohm Stable
150 Watts x 2 into 4 Ohms
300 Watts x 2 into 2 Ohms

[MacLeod]

Cant rely on factory specs that much. They sometimes "exaggerate" the ratings or just flat out lie. Take Xtant. Their amps are rated at 1% THD! That sucks. Yet they are routinely in the winners circle in SQ competitions. JL Audio 300/4 amp rates signal to noise at 108 and Carsound.com's review tested it on the bench and rated it at 120!! Then you have amps like my beloved little 40x4 Alpine. I would wager that this thing would be lucky to hit 35 watts on a good day! And hell, Pioneer amps are rated THD at .004%! But would you rate a Pioneer amp better sounding than a .02% Precision Power amp?

Numbers dont tell the whole story. I would suggest just going to a shop and giving different amps a test listen. Take the CDs you listen to and know well and check out the different models. Dont rely on what I think sounds good, be your own judge.

[MrDHEJ]

Macleod:
Theres no one close to me that has US Amps, so i must go on "word of mouth" or ear, for which is better.

Jstas/MTXMAN:
The JL Stealthbox for my truck has a volume of 1.25ft and is sealed. So what MOMO sub would be a good choice?

sntnsupermen131:
I took some pictures today, i'll upload them here soon at the follwing url

http://www.renagaderc.com/automotive/1999Silverado/1999silverado.html

Looks like i will have to cut the holes in the mounting bracket so the seat can slide forward another 1/2" to an 1". The way it is now i wouldn't want to use the radio when the seat is up becasue the back seat cushin will touch the amps and block cooling. With the seat down though theres like 2" to 3" of clerance. You can see in the photos the ducting i was talking about. Think i will call GM tomorrow and see why those are there.

[MTXMAN]

You get a completely different sound with a tube amp. Jstas can back this up having delt intensely with tube amps in his home stereo. It's much warmer and more detailed. while the class AB amp will be louder and covers lower frequency(ones you'll never use anyway) and has a lower THD% I personally would prefer the tube because of the type of sound they reproduce. run a search on the site for tube amps and look at what people say about them for home audio cause the results will be similar. warm detailed gorgeous sound. :D

[MrDHEJ]

that's all i needed to hear. :) Thanks man.

So as far as the JL box having 1.25 feet of volume, what 12" sub would you recomend? Are the polk sub just as good as there full range?

[startzy]

dude id go with a polk sub if the jl box is sealed the polk gnx124 will fit in a sealed box with 1.25 of air space and that sub kicks ass man

[Jstas]

Well, about the tube amp, I have reservations about them in cars. Not because of sound quality because they do have a very warm, natural sound. Tube amps are delicate and susceptible to vibrations. I worry about them in cars because a good bump could break a plat or filament in a tube and then you are buying a new tube to replace the broken one. That can be expensive depending on what tubes that amp uses. But if you want to go with a tube amp, more power to you! I will warn you though, tube amp power is not like solid state power. 100 watts of tube power has more grunt behind it than 100 watts of solid state power. It's not physically more power or over-rated or anything like that. Tube power is just delivered much smoother and tube amps often have a higher sensitivity rating than thier solid state counterparts. The solid state amps can out-muscle the tube amps, especially in D-class form. But I have yet to hear an AFFORDABLE solid state amp that comes anywhere close to the richness of a tube amp.

As far as woofers goes, the GNX is what looks like will fit best for a 1.25 cubing inch box. However, you are not limited to it. If you can fill in some space inside that box, you can reduce the volume of the box internally. If you do that, you can make the box internally smaller and get a Polk MOMO 2124 which I feel is a better sub than the GNX.

To reduce space, get creative! Since the stealth box is most likely an odd shape, you could get a guage plastic bag like what you would find in a sandbag. Fill it with sand and wrap it in burlap. Figure out a way to safely secure it inside the box so it doesn't move and stuff the box with polyfil. It's not the best solution but it would be easy to get say .35-.40 cubic feet of sand in a bag(s) to reach the .88 cubic foot requirement of the MOMO 2124.

If the box is flat, figure out the volume of some lengths of wood that will fit inside the box and fasten the wood inside the box to reduce internal volume. To determine the volume displaced by the wood, multiply length by width by height of the wood and just add enough to equal .35-.40 cubic inches. Use measured sizes though because milled lumber is never milled to an exact dimension other than length. A 2x4 is never 2 inches by 4 inches. Believe it or not, that is a standard though. Again, fill with polyfil and go to town!

Just remember, it is always better to build the box properly but sometimes we have to compromise and that means something like a stealthbox needs to be modified to fit our needs and appication. There is nothing wrong with it and if you take your time and think about what you are going to do, you will get very good results and be exteremly happy!






Until the upgrade bug bites again! Then you can come to the Club Polk support group...Hi, my name is John and I am an audio junkie.

[PoweredByDodge]

ok - normally i dont chime in on a thread until i actually read it - and forgive me if i'm saying things that were already said, but i'm about 10 minutes away from my lab final and i'm just tryin to get in what i can here...

i'll try to respond better (if necessary) when i get home later.

as far as the amp -- the 1000x is 1000 watts... dude... why not buy like a 300 or 400 watt amp -- that 1000 is HUGE in both size and power - - both of which you do NOT need.

second -- you cannot fit an idmax in a stealth box... regardless-- 1.45 or around there cubic feet sealed birch ply or mdf box and dont fk around with it cuz you will blow the box apart... literally. wicked sick heavy sub and creates and assload of pressure.

and IDQ however will fit. but... ifyour'e gonna do an idq - why not just do a polk momo 2104 or 2124 -- i'm more partial to the "we sorta are like old db's / dx's" polk subs that just came out... i dig em.

just watch air space... check on that -- from what i know, JL audio subs take LARGE airspaces -- polk and id and most good sq subs take small spaces.

alpine type R might be a better replacement - u can put it in a bigger box i think -- so if u have a "big" stealth box -- check that out.

as as your other speakers -- why the hell aren't you getting a 4 channel!!!!!!!!!!!

pick up a 75 x 4 USamp tube or not tube is irrelevant -- tubes are nice, but john has expressed concerns which are probably valid especially in a pickup that's shaking around a lot (not as smooth as a luxury car or whatever) -- but think it over -- i really think a 75 x 4 is plenty powerful for 4 coaxial speakers dude.

on that note -- beer and chicken -- imma go have a cigarette before this thing -- WISH ME LUCK!!!!!!

[MacLeod]

You dont need that much grunt in a pickup. There is a lot less room in there and the sub is about 2 feet away from you. Ive got 140 rms running an MTX 8 in a Ram Quad Cab and its plenty. Now this isnt a ghetto blaster, you cant really hear it outside the truck but inside its plenty. I would say that anything over 250 is a waste as youd never use it all. It would be way to loud and rip your eardrums out.

The same goes for the mids/highs. Ive got 4 speakers getting 40 rms each and again, its plenty. Its enough to run down the freeway with the windows down and still hear everything. I would say that the best for a pickup SQ system would be 50x4 and 250x1. I think that will give you a good, clean, really stout system. Any more than that is simply not needed and will not ever be used. Now if youre wanting to blow out the windows in the car next to you or enter some DB Drag competitions then yeah, go as big as you can. But its kind of like driving an 18 wheeler as a daily driver. Do you really need all that room?

Thats the cool thing about a truck. You dont need 5 zillion watts to have a stout SQ system.

[MrDHEJ]

All good information.

As far as the coaxils go, the reason i don't want to run a 4ch amp is because the MMC460 is max 100watt, so 75watt from the 4 channel comes up short, and the MM6's are 150wats, which is 1/2 of the 4 channel. So to get each set at there max the TU-600 and the USA-400x will be perfect.

With tubes yes i agree there is a risk, but for a company like US Amps i'm sure they tested them quite well, so i will give it a shot.


Now as far as the sub and sub amp goes, yes 1000watts is allot, but the Polk 2124 can handle almost all of that. Will i use it all, all the time? No, who does. But when i want to use it, i want it to feel like someone in the back seat is kicking the shit out of me in the back. :)

All in all my main goal is SQ, and the US Amps in combination with the polk speakers will come thru. And on those days i feel like ringing it out the power will be there, and everyone close will know i ain't messing around.

Plus later on i don't want to be saying "Man, wish i had gotton those other amps".

BTW, the USA-1000x, TU-600, USA-400x will fit in the truck, out of sight, out of the way. :)

BTW, with the Polk 2124 will that take the USA-1000? or the 1000x.

[sntnsupermen131]

you would want the 1000 for a single 2124
and the mmc460s are only rated at 50, not 100
and if you crossover the mm6s at 100Hz, you could probably but 250 watts on them if they were nice, clean watts, and youre not a total idiot...
i have 225watts going to each crossover safely on a fosgate
that amp is awesome
i wish RF would still make them like they used to, its almost doubling its rated amount of watts
rated at 500, putting out almost 850
the new versions i have put out about 75 watts over the 500 mark
they dont make them like they used to...
-Cody

[sntnsupermen131]

also, why dont you go with a mm124 instead?
-Cody

[Jstas]

Originally posted by sntnsupermen131
also, why dont you go with a mm124 instead?
-Cody

Because the mm124 will be alot harder to make work in a large Stealthbox like he has.


As far as the power levels go, power levels are not so much for volume as they are for sound quality. You don't have to use all the power but the sound does get better with more power because when you listen at normal listening levels, you have alot of power overhead available. It reduces the chances of the amp clipping and helps stave off distortion because there isn't enough power to move the cone accuratly fast enough. So just because it is a pickup truck and you are sitting almost on top of teh speakers doesn't mean high power is a waste.

As far as subs go, they usually require 3-4 times as much power as your fuill range speakers because they need to play that much louder. They need to play that much louder because the decibel levels of bass increase almost exponentially as the frequency levels decrease. That is because the human ear's effectivness decreases as it approaches its limits. It's something like for ever step down in frequency from 50 Hz, the decibel level has to increase one point or something like that. By the time you reach 20 Hz, you have to have your sub playing that much louder than your full-range speakers, just to be able to hear the 20 Hz frequency. Therefore, a high powered sub is necessary for your ear to be able to physically hear all the information in the bass track.

[MTXMAN]

if it's a 4 ohm sub get the 1000x, if it's a 2 ohm sub(dual 4ohm vc's) get the 1000... simple :D

[MacLeod]

I guess it all depends on what kind of music you listen to. I listen to metal and my little 140 watts to my sub is usually too much. It drowns out the mids/highs which is 40x4. If I turned the mids/highs up much more my ears would start bleeding. A screeching guitar starts to become painful at a higher level. Thats why I think 50 rms is plenty on the mids and 250 is all you need for the sub. Its enough to be plenty loud without approaching its max ability. I rarely turn my volume up more than halfway and its almost to the point of hurting then (well provided its a good recording).

I guess if youre more of a hip/hop guy then a lot more ass in the bass is what you need.

[Jstas]

It doesn't matter what you listen to. If your sub is drowning out the rest of your stereo, your system is unbalanced. Either turn up the gain on the full-range speakers to match or turn down the gain on the sub amp to match the full-range.

Different recordings can have variances. I have the same song by the Eagles on two different CD's. One was recorded in the early 90's, the other was recorded from masters made in the late 70's. The early 90's recording was much more robust so the volume levels were high but the song was still balanced on the stereo.

Different kinds of music will have different characteristics but, one aspect should not over-power the others anymore than the producer of the album intended it to. If you are turning your volume up halfway and hitting ear bleeding levels and having your sub over-power everything else then I will venture to say that you have your gain settings set too high. You should not be hitting peak, distortion-free performance anywhere before 75% of full volume at the minimum. A much more reasonable figure is about 90% of full volume.

[MacLeod]

I dont listen to my music with the sub drowning out everything else. I use my sub level control on my HU and adjust it accordingly. I have it set that way to compensate for cd's that have very little bass and to have some room to crank it if I want to.

And my mids and highs arent at peak levels at half volume. They are however at the limits my ears can handle at 60% as long as its a good recording. I leave a little more room for the same reason as the sub, for the cds that are not as loud and also for a little more room for when Im cruising down the freeway with the windows down.

All I was saying is that with the mids and highs playing as loud as tolerable, a humble 140 watts could keep up and even drown them out in the cab of a pickup.

[PoweredByDodge]

--- aced my final :) ... we had to flip coins to determine what project we'd have to build... i flipped "bandpass network" and i just about laughed myself silly... build a bandbass crossver network with a highpass for 20 hertz and a lowpass of 20,000 hertz. then run a wave generator though it and prove it works on the o-scope. with shitty ass parts i still got it to about 19.5 and 20,000 on the dot. ----

as far as percentages of volume level -- i'll concur with that but with the limitation that this is pre-clip volume... my headunit's rca preouts distort/clip at 23... the deck goes up to 35 though... but its all clipped out and shit... i've tested and tested and screwed with and done everything - but tried and true.. that's what it does.

i've got the gains set so that i get my "totally highest loudness that i want to listen to normally" at about 19/20 ... 21 and 22 are for pissing of the neighbors, pickin up chicks, or other nefarious stupidity. 23 is for when i'm in a bad mood and have been drinking a lot.

24 ... 24 is like that scene in ghostbusters.... "dont cross the streams" "why?, what'll happen" "just trust me, it'll be bad."


as far as 150 watts being enough... in a standard cab pickup -- ehhh... maybe. prolly... ya. in an X-cab.. more like 200 - 250 .... and i'm not talking rap, i'm talking like just making some Bruce Springsteen sound right.

oh that note -- the friggin shit died in the old man's truck and I dunno why... sub works, right side speakers work -- left side speakers dont... wtf... now i gotta go venture into the cold and figure that one out.

[MacLeod]

24 ... 24 is like that scene in ghostbusters.... "dont cross the streams" "why?, what'll happen" "just trust me, it'll be bad."

LOL!!!! Thats too good!

I used the ole "turn your volume to 3/4 and then turn up your gain til you hear distortion then back down a tad and there ya go" method to set my gains. Then I set my sub gain a smidge higher than that. That seems to work pretty good. At that level my rig doesnt distort til 30-32 depending on the recording.

I didnt mean to imply that 140 watts is all you need just that if budget or space constraints are a concern, you dont absolutley have to have the 1000 watts back there. I built a budget system to hold me over the year or two it would take to put my "dream" system together so I opted for the $110 Alpine amp.

However I am designing a hi end system for my Ram and am planning on no more than 300 rms to the sub (which Ive not decided on yet).

[DJ Kontakt]

theres no reason to provide an external amplifier for your rear speakers, it will set your imaging off balence. Get a HU with an internal amp to power them.

DEF lose the JL sub and box. You cant just put any sub in the box and expect them to perform as well though, as JL designs those boxes specifically for the sub it is loaded with.

It would work though.

[ilikeboyz]

Originally posted by DJ Kontakt
You cant just put any sub in the box and expect them to perform as well though, as JL designs those boxes specifically for the sub it is loaded with.

It would work though. actually....it is just an enclosure...no magic inside it;) ...if we caqn get the exact measurements...and it is built up to par...it can have many uses

[Jstas]

Go back and read the WHOLE thread this time and you will see that this has already been covered in detail. There were several solutions presented and the whole reason that the Stealthbox was chosen was space requirments. Not everyone devotes all available space to the holy grail of audio nor can they afford to. Budget and utility requirements are just as important as sound stage, power levels and volume.

[DJ Kontakt]

Originally posted by Jstas
Go back and read the WHOLE thread this time and you will see that this has already been covered in detail. There were several solutions presented and the whole reason that the Stealthbox was chosen was space requirments. Not everyone devotes all available space to the holy grail of audio nor can they afford to. Budget and utility requirements are just as important as sound stage, power levels and volume.

wtf man I was just giving support to the solution that I agreed with the most. Maybe that extry yes will help him decide.

go help yourself and rewire your car or something

[Jstas]

That wasn't directed at you. If you took it that way, I'm sorry.

[DJ Kontakt]

ohh ok. sorry then. lol just used to all the flaming :P

[MacLeod]

As far as an amp for your rear speakers, I like using one although I use and recommend a 4 channel. This way you can adjust the gain so the rear output is less than the front. This way youre asured of good clean sound all around and still have the imaging toward the front.

And Im with ya on the space issue. Im having that same problem with my system. Im using the middle section under my rear seat for amps and the drivers side for tools and other stuff. The passenger side is reserved for my sub but its awful small. My first try at a custom fit box was .3 cubic ft and Im not real happy with it. Im going to try to figure out how to get around .55 or .6 and port it but due to my rather...shall we say..."humble" carpentry skills I may be forced to pay for my local shop to make me a fiberglass enclosure.

[Jethro]

Originally posted by MrDHEJ
Going in a 1999 Chevy Silverado Ex-Tended Cab

Front doors: MM6 6.5"
Side rear panel: MMC 4x6
Under rear seat: JL Audio stealthbox 12"

US Amps TU-600 driving the MM6's
US Amps USA-200X driving the MMC 4x6's
US Amps USA-1000X driving the sub

How good do you think this combination would be in terms of SQ?

Only problem i may encounter is where to put 3 amps. Only thing atm i can think of is putting the amps in a box ajacent to the sub on the floor under the rear seat.

If you paid good money for the Stealthbox, leave the JL sub in there. It has more Xmax than the GXR or the MM2124 (11.8mm for the JL vs 9.5mm for the MM2124), and will have a lower Qtc in 1.25 cf (.83 for the JL vs. .87 Qtc for the MM2124).

Don't waste amplifier power on rear fill. Run them off of deck power so that you can fade them out completely when you have no passengers. Multiple sound source producing the same frequencies from different locations inside a vehicle will only degrade your sound stage and your image.

[Jstas]

See, this is a perfect example of what I hate about car audio salesmen and most other car audio forums. Why don't you listen to what he WANTS rather than trying to convince him that what you like is what he likes? If he wants rear speakers amplified, let him have rear speakers amplified. If he wants to replace the JL sub, let him replace the JL sub. There is nothing wrong with what he wants to do. It fits his needs and desires and he seems pleased with his plan. In my book, that would be called a happy customer!

On top of that, you have done him a dis-service. He is obviously a novice to car audio and you have thrown some technical jargon at him that he may not understand. Why don't you explain to him what Xmax and Qtc mean? If you educate him, he will be able to make a more informed decision.

[MrDHEJ]

It's all ok guys. Yes i'm fairly new and learning fast. I thank you all for your help, even if it's bad help. :)

One reason i don't want the JL sub in the stealth box, is mainly it's not Polk. I know how the Polks sound, and i doubt they have better SQ then the JL's. Maybe there not as loud, but i'm not looking for Db here, i'm after SQ. That's why theres going to be $1400 in US Amps in there as well.

As far as running an amp on the rear MMC460. There rated at 50w cont, 100max. My DEH-P77DH only puts out 22rms, and when cranked i'm afraid i'll end up cliping the rears if there un-ampd.

The USA-400 is rated at 50w at 4ohm, and if they are to loud i can always turn the gain down, or use the decks fader. Either way, they need to be ampd or there not going to sound right, and may get damaged.

Jstas, i hate salesmen. I would rather a tech tell me not to use something then explain why. It's not about what i want as far as products, it's what products i need to get what i want. :)

balls to the wall it's all about SQ. I gave the wife an early xmas preset and put her Polk MMC650's in the rear deck of her Maxima. My gawd i forgot just how good Polks sound. and that's with deck power. She has no idea she's getting a TU-4360.

Anyway, theres no need to flame or anything, we all can't know everything. I'm sure your all very knowlagable, but i'm also sure were all wrong sometimes. It's like Jstas said, if you know why one spekers is better then the other tell me why, then tell me the pros and cons.

Thanks guys.

[MacLeod]

Hey, I admit Ive not read this entire thread cause Im lazy so this may be old news....but have you thought of a box from Qforms or Obscom? they are around $200 which is a lot cheaper than the $500 Stealthbox. They make one for my Ram that houses a single 10 and fits as well as the Stealthbox at half the price.

Ive never used one so I dont know much about em. Just thought you might want to give em a look see.....that is unless you guys have already discussed this at length! Oops :D

[MrDHEJ]

MacLeod: Do you have there website? i havn't bought the stealthbox yet.

[MacLeod]

Try Crutchfield. They carry all of Qforms stuff. Ive got their as well as Obscoms website here somewhere and Ill post it when I get it. Go to www.crutchfield.com tho 'cause you can look up the exact vehicle specific box and get a price as well.

[MacLeod]

www.qlogic.ws/2003/home/ This is Q Logics site.

www.obcon.com This is Obcons.

[MrDHEJ]

Well, they list a Q-logic that fits my truck, but i don't like how it looks, and it's to small in volume for the polk subs. :/

Easier to fill a large box, then make a small box bigger.

I like how the stealthbox is carpeted.

[MacLeod]

Circuit City can get you these things as well as most car stereo shops if you dont want to buy online.

[PoweredByDodge]

do not - under any circumstances - buy a plastic box for your subwoofer.

i had an mtx thunderform for my ram back in teh day... its tthe same material that Q logic uses for its Q forms...

plastic... no good at all.

it'll flex and bend.. and its bad.

JL however uses fiberglass and what not -- and that's good... that's perfectly fine and just as good as a well built wooden box.

i would highly recc the stealth box over anything else (unless you get a little wooden box made to fit and carpeted and look nice and shit - then that's fine too).

anyway... head unit power is not full bandwidth usually... often its hacked off with low response and peaky here and there... not to mention that its horribly distorted and often more mechanical sounding than anything else you'll ever here (sorry i stole u're "mechanical" term Jstas, but it applies here).

I respect a man who wants to amp his rears -- it shows attention to detail.

rear fill is often essential... some people dont require it.. dont want it.. whatever... but i found that in a decent sized vehicle - such as an x cab pickup - you need SOMETHIGN... even if its only 1/4 to 1/5th of hte power of your front speakers... but SOMETHING to fill up the rear.

anyway -- that's my two cents...

find a polk sub with proper air spacing -- throw it in the stealth box... throw a shitload of power on it... amp up the fronts and rears as you had planned and go to town -- you didn't do a bad job for a "newbie" dude... you seem like you may not know the tech, but you certainly have the general idea down and you've got an attention to quality of the system and pleasure of listening to it.

dont get distracted.

[MacLeod]

Yeah, I wasnt sure about those Q Logic but thought they were worth a look see. Ive never tried one and dont know anybody who has. Well now that I think about it that alone should have been evidence they aint all that.

[MrDHEJ]

I talked to one of my friends here in town that used to do custom radio installations a few years ago, and he suggest instead of getting the stealth box we make one that will be suited for the polk M124 with a volume of 0.88 feet. It'll take up less space and he already has all the stuff to make one. so that should save me about $350 and will comform better to my truck. :)

Is the 0.88 cubic feet with or without the speaker in it?

[MacLeod]

I think that sounds like a good idea. Especially if you got a pro handy that can give you a hand. You can build your own box for under $75. A sheet of 3/4 MDF is $20, wood glue and sealer is about $7, screws are $2, jigsaw for $20 and you can get a sheet of carpet from your local shop for $5. The hardest part is doing all the math and designing the box but once that is done, and if youre have some skills with a saw, it shouldnt be a big undertaking.

I used MTX's website (www.mtx.com/caraudio/education/index.cfm) when I built mine. It has a lot of good info you should know before you start building or even designing. And seeing as how this was my first attempt at building a box (I got cheap) it was very uselful to me.

[sntnsupermen131]

you need to build the box to .88, displacement of the sub has been accounted for
agreed on the q-logic boxes, they "q-ring" sucks ass, it leaks air, which could cause damage to your sub, well, maybe not that one cuz i think you can use it in ported boxes, but it might, and you might get some hissing noises where the air comes out
have fun building the box and good luck
when ur making ur measurements, be sure to take into account that the wood is 3/4" think if your using 3/4" MDF, which is what i use, if you use particle board, youll blow it to pieces
-Cody

[MrDHEJ]

We both have fabrication experience, and we both have the tools to do it. I just got to go get a sheet of 3/4" MDF and some carpet to match my truck.

The math is no big deal, Excel spreadsheets make it easy to change deminsions on the fly and have it caculate the volume. :)

The USA-600x and Polk MM124 is on it's way. I still need to get the power wire and i'm going to have the inside sprayed with Rhino Lining for sound dampening.

It's going to kill me having to wait to get all this done, but i'm sure the wait will be worth it.

[PoweredByDodge]

if you dont mind spending twice as much money on wood (30 instead of 15) ... get a sheet of 3/4" birch plywood cabinet grade material --- the box will last 300 years :)

sturdy stuff... but mdf is fine too :)

[Jethro]

Originally posted by Jstas
Why don't you listen to what he WANTS rather than trying to convince him that what you like is what he likes? If he wants rear speakers amplified, let him have rear speakers amplified. If he wants to replace the JL sub, let him replace the JL sub. There is nothing wrong with what he wants to do. It fits his needs and desires and he seems pleased with his plan. In my book, that would be called a happy customer!

My response was directed at this part of the original post:


Originally posted by MrDHEJ
How good do you think this combination would be in terms of SQ?


I was offering advice on how to get the best possible SQ out of his system. Your suggestion of replacing a very capable JL driver with lesser Polk drivers would achieve the opposite result.


Originally posted by Jstas
Just pull the crap JL subs and unload them on eBay to some kid that buys into the JL hype for 3 times what they are worth and load the stealth box with subs that can handle the power.

The JL 12W3v2 will handle more power than a GNX, GXR, or MM2124. The greater excursion capabilities (Xmax) also mean reduced distortion. As a sub gets closer Xmax, distortion increases due to compliance loss (suspension gets stiffer) and decreased motor strength.

It is not just a matter of output, but a matter of reduced distortion at realistic listening levels.

[Jethro]

Originally posted by MrDHEJ
One reason i don't want the JL sub in the stealth box, is mainly it's not Polk. I know how the Polks sound, and i doubt they have better SQ then the JL's. Maybe there not as loud, but i'm not looking for Db here, i'm after SQ. That's why theres going to be $1400 in US Amps in there as well.

As far as running an amp on the rear MMC460. There rated at 50w cont, 100max. My DEH-P77DH only puts out 22rms, and when cranked i'm afraid i'll end up cliping the rears if there un-ampd.

The USA-400 is rated at 50w at 4ohm, and if they are to loud i can always turn the gain down, or use the decks fader. Either way, they need to be ampd or there not going to sound right, and may get damaged.

Jstas, i hate salesmen. I would rather a tech tell me not to use something then explain why. It's not about what i want as far as products, it's what products i need to get what i want. :)

balls to the wall it's all about SQ.

Fair enough. It was just a suggestion. I am sorry if I confused you at all by using terminology that you were not familiar with.

Here is a site that explains Qtc:
Sealed Speaker Enclosure Design (http://www.carstereo.com/help2/Articles.cfm?id=29)

Here are the MM124's Vas, Fs, and Qts values:
MM124 (http://www.crutchfield.com/cgi-bin/S-j3tNzhJxRND/ProdView.asp?a=0&s=0&cc=01&g=67700&id=features_and_specs&i=107MM124)

To convert liters to cu ft, divide Crutchfield's spec by 28.32. Here is a calculator to determine the Qtc of a given enclosure:

Qtc Calculator (http://www.carstereo.com/help2/Articles.cfm?id=30)

I see you have decided on the MM124 - an excellent choice. But, if you are truly "balls to the wall it's all about SQ", you may want to put that driver in a slightly larger box than .88 cu ft. You will find that 1.25 cu ft or even larger will give you a little better low-end and a little less upper bass empasis.

Again, just a suggestion for maximum SQ. If you are already set on .88 cu ft, just stuff with polyfill and you should be good.

[sntnsupermen131]

Jethro, wouldnt by increasing the box size the SQ go down
im wondering because if it has more air, the sub can not control itself as well b/c its "backbone" is not supportive enough?
-Cody

[MrDHEJ]

Now, in regards to using birch plywood for a box, back when i started messing with car audio i did some research and found that you SHOULDN'T use playwood, or other hardwoods. If i remember corrctly, it was because the harder material would resonate and sound crappy. Has this changed?

The information here on the Polk site in regards to box volume states: A smaller box will require more power, but produce tighter bass in the whole spectrum, where as a larger volume box will focus more on the lower freq. and be more boomy and louder at a sacrifice to the higher bass freq., but require less power.

[PoweredByDodge]

yes u are correct -- almost all plywoods SUCK.

plywood is "grainey" with knots and other junk... and its generally not very dense at all... and it will resonate...

but baltic birch cabinet grade plywood that's 30 - 35 bucks a sheet is not... this type of wood tends to be very dense... as dense if not more dense than MDF. also... it is amazingly rigid... i would say twice as rigid as MDF (maybe not twice, but look at it this way... if you had a 2000 watt sub that required 1" MDF, you could build the box for it that would be just as good as the 1" MDF box out of 3/4" birch ply that i spoke of).

I've used birch ply for three boxes now and in my opinion it totally obliterates the MDF boxes i've built before. it holds up so much better, is so much stronger, and the screws do not split the wood nearly as much as they tend to split the MDF (and yes that is predrilled MDF -- splits anyway).

Thom, the polk installer dude, said he swears by cabinet grade plywood -- I had intially told him and Jstas they were "fulla it"... but after trying it out for myself on a whim I found them to be nothing but absolutely right.

They suggest using cabinet grade ply with liquid nails and a brad nailer... however since i dont have a brad nailer (hammer wont work) I predrill and use drywall screws with either a foam thin gasket between all joints or some heavy duty silicone between joints (messy but it works) -- then seal all internal corners with a good bead of silicone (for either MDF or ply -- u need the seal inside).

if you want a better explaination of why this works the way it does - i would hope that Jstas can give you that... I really don't much understand what it is about the two wood types that makes one kick the shit out of the other... nor what properties of a good cabinet grade wood make it as dense and more rigid than MDF, but he has more of a good idea why -- sadly in this area I am left with no better explaination than "cuz it is" -- which is a really shitty explaination, but none the less the honest truth.

[Jethro]

Originally posted by MrDHEJ
The information here on the Polk site in regards to box volume states: A smaller box will require more power, but produce tighter bass in the whole spectrum, where as a larger volume box will focus more on the lower freq. and be more boomy and louder at a sacrifice to the higher bass freq., but require less power.

That statement is not totally correct (with regard to sealed boxes, anyway). A sub with tight bass typically has excellent transient response without a lot of overhang or ringing. This is usually attained by using a sealed box alignment at or aroung .707 Qtc. "Boominess" is usually defined as too much upperbass emphasis - a characteristic found in boxes with .9 Qtc or higher (smaller boxes).

A smaller box will indeed require more power, but it will also have better power handling. When designing an enclosure for SQ purposes, you want a Qtc as close to .707 as possible, while keeping within the driver's excursion limits.

If you took the MM124's Thiel/Small Parameters.....

Electrical
Overall Frequency Response 20Hz - 200Hz
Nominal Impedance 4 ohms
Power Handling (continuous) 500 w
Power Handling (peak) 1000 w
Efficiency 87 dB
Voice Coil Diameter: Driver 2" (5.08cm)
Magnet Weight 66.00 oz.

--------------------------------------------------------------------------------

Driver Mounting Depth
Top Mount 6" (15.24cm)
Bottom Mount 6-1/2" (16.51cm)
Cut-out
Driver Cut-out Diameter 11-1/8" (28.26cm)

--------------------------------------------------------------------------------

Theile/Small Parameters
Recommended Enclosure Sealed or Band Pass
Resonant Frequency 27.5 Hz
Qms 13.06
Qes 0.476
Qts 0.46
Vas 81.12 L / 2.865 cu ft
Cms 221 Micro Meters
Bl 14.45 Tesla Meters
Sd 511 sq cm / 79.21 sq in
Xmax (mechanical) 1.0
Le 1.92 mH
Mms 151 g
Driver Weight 15.8 pounds
Pe 500w

.....and entered them into WinISD Pro (http://www.linearteam.dk/default.aspx?pageid=winisdpro), you would find that it could take 600w RMS in 2 cu ft sealed without exceding the 25mm Xmax (Qtc would be .717).

1.25 cu ft would get you a Qtc of .83, which is on the upper limits of what is considered an SQ alignment.

.88 cu ft would yield a Qtc of .93, which would have great power handling, but would be a little boomy for SQ purists, unless you had an EQ to tame the boost in response between 60 and 100hz.

For more information on this, check out The Loudspeaker Design Cookbook by Vance Dickason. The newest edition even has a section on how a car's interior boosts (aka transfer function or cabin gain) the lowest octaves, and how that transfer function varies from vehicle to vehicle.

[Jethro]

Originally posted by sntnsupermen131
Jethro, wouldnt by increasing the box size the SQ go down
im wondering because if it has more air, the sub can not control itself as well b/c its "backbone" is not supportive enough?
-Cody

If you go too large, then yes, power handling will be decreased to a point that SQ will suffer due to over-excursion (typically with Qtc's lower than .577, depending on the driver). But, enclosure size is relative - some 12's work well in 6 cu ft+, other 12's work well in less than 1 cu ft.

For a better explanation than I could ever give, follow this link:

Sealed Box Tutorial (http://www.jlaudio.com/tutorials/magic/sealed.html)