04 GT Sub install (finally)

Did you math out the required volume for those subs? Where are you getting the 2800 number from? Did anyone tell you that anything over 8 inches in a short interior is a waste of time? What did you do to the rest of the system to compensate?

Never tried putting a system in a newer Mustang. I had a Fox hatch that sounded nice though. Clarion 300W sub amp pushing two MTX 12's, Kicker 40x4 pushing Kicker 3" front and 6" door speakers, Kicker 40x2 pushing Clarion

5x7 rears... all co-axials (I know, sound quality isn't the best, but 6 tweeters all around the car and aimed at your head didn't hurt). PLENTY of sound to compensate for the bass... couldn't overpower the system with the bass with the 300W amp... but it was really 300W... I seriously question the ratings on some of these amplifiers that claim 1000W in a package the size of my 300W system.

Needed no capacitors, extra batteries... just some good wiring and a decent alternator. Could still hear me coming a block away... crystal clear inside the car regardless of the setting of the volume knob.

Next system I install, I'm borrowing the 4-channel color digital oscilloscope from work and tuning it right though..

JS

I actually mathed it out and im a bit short, but its as close as I'll get.

I put in two pyle blue wave 15" subs, each rated at 1400W max. Behind each one is an 800W reason amp that peaks ~1300W.

Both amps are wired right into the mach 1000 on the stock amprack, and draw power throgh the battery and a 3 farad monster of a capacitor.

I'll post pics, but what I basically did was make my whole trunk a box. Built a custom panel that sits flush behind the back seat shroud (thats why I wanted to remove it, but worked around it). The cones face in to the car, about 2" behind the back seats when they're up. The back is wide open, so the whole trunk is a huge sealed box.

Math works out ok, if I were to pull the carpet and spare tire and add that volume, I'd be perfect, but Im not planning on that, daily driver and all.

Kicks very hard, and with an ultra-low intelligent crossover (5-80db crossover) it doesnt overpower at all.

As general commentary on this topic, let me just say a couple things that address some of the fallacies in audio.

First, using nominal handling wattage of a speaker to describe a system is wrong. Speakers do not create wattage. The proper way to describe power output of a system or part of a system is the RMS number of the amp(s) driven into a static 4-ohm load at a low distortion level (THD). "Peak" power or Japan industry figures are misleading and are solely quoted to get consumers hyped (sounds like horsepower, yes?).

Notice I used the word "static" above. This is important for the next point. Another marketing gimmick is quoting figures at 2 ohm loads. This typically doubles the rating, making the amp appear more powerful than it is. Problem is, running a 2 ohm rated load means that the amp is going to see momentary impedance levels below 1 ohm. This is because music is not static; it's dynamic. Deep bass reproduced by big drivers is going to cause momentary low impedance. This reduces the effectiveness of the amp to control the drivers and deliver *accurate* tones.

Many amps claim to be 1 ohm stable. This is not to be confused with being *accurate* with a 1 ohm load; it just means there is some kind of circuit protection on board.

The higher the impedance, the more control an amp has over the fore and aft movement of the drivers. Picture pedaling downhill on your bicycle. If you are in high gear, you can still move your legs against the resistance and maintain stability. In low gear, you are windmilling your legs like mad but can't keep up with the speed.

To an ear striving for accuracy, the "sacrifice" in power output going from a 2 ohm to 4 ohm rated load is worth it. Not only will distortion come in at a much higher volume level, but the amp(s) will run cooler and last longer. Note that most home speakers are 8 ohm, even though the power source is more stable than a car's.

Lots of guys will wire four 4-ohm speakers into a stereo (2 channel) amp, hooking them up in parallel. This gives a nominal 2-ohm load. I had several such people come into the shop complaining of "blown" speakers and distortion at moderate levels. The fix? Remove the wires at the amp and hook them up in series to achieve an 8-ohm load. Distortion gone. Not a one of them moaned about "cutting down the power", because the end result was plenty of volume and clean music. And I didn't rip them off by replacing good parts.

Going back to subs, let me yak about driver size. Big drivers have been hyped over the years as necessary to achieve "big" bass. This is a marketing ploy (and a damn successful one) that skirts the physics of acoustic reproduction. In home systems, large drivers are employed for their ability to create low frequency sound waves in large areas. In cars, these low frequency waves have a length that exceeds the length of the vehicle's interior. This is why you hear "better" bass outside the car; inside what you are experiencing is air movement and some representation of the upper harmonics of the sub bass tones.

Every driver had cone mass. The bigger the driver, the more power it needs to move that cone back and forth to reproduce the sound waves. The smaller drivers are more efficient in that they have less mass to move. But, they don't move as much air and are not as forceful down low as the big drivers.

What to do? Simple. Run multiple small drivers. Now you have more total cone mass with the added bonus of more voice coils moving it faster. Phased adjoining drivers will create waves that "melt together". Such an array will go low and do it cleaner than big drivers, which often give that muddy one-note boom (worsened by band-pass boxes) that so many of us hate.

The trend towards huge drivers leaves an inherent hole in the mid-bass. They cannot move fast enough to give crisp bass transients and percussion that inhabit that 100 to 300-cycle area. The "fix" here is to build a four-way system that uses smaller bass drivers for this area (note that 5 or 6-inch bass drivers are built differently than the same size midrange). This will help the overall problem, but you are still left with lazy sub bass.

In a standard passenger car interior, I have found that anything over an 8-inch driver slows down the sound. In a van or SUV, a 10 is acceptable. In a mini-truck, well...

One of my installers had a Toyota mini years ago. Following the "smaller is better" criteria, he built a box behind the seat that employed six 6 1/2" bass drivers per side, wired in series-parallel for a 3-ohm static load. The upper AND lower bass reproduction was incredible. And it sounded better "inside" the truck than outside, and used far less power doing so. And the box was thinner than "normal".

A further illustration of this is the home subwoofer array that Yamaha used to sell a few years back. It hung on the wall, about 3 foot square, and maybe 2 or 3 inches deep. There was one small port on top. During a new product demonstration put on by Yamaha, we (dealers) were treated to amazing sound with all kinds of different source material. The streamers attached to the port for show were almost vertical the whole time. The accuracy was awesome, and filled the entire meeting room. With a flourish, the rep pulled the speaker grille off to reveal, you guessed it, sixteen 4-inch drivers. Unreal.

Some of my best sounding stuff used four 8-inchers in boxes that were half the size of two 12's. In most instances, a single "quality" driver is all that's needed. Money is better spent on a "quality" amp. Unfortunately, too many people go for multiple cheap drivers and some bargain amp with a big bogus rating. Then they brag about blowing up the speakers with too much power, when in reality the amp clipped when overtaxed and cooked the voice coil(s).

And speaking of clipping, adding truly powerful amps to a car necessitates attention to the charging system. Big capacitors helps rapid transients down low, but they do not "create" power. An upgraded alternator should be considered, but also pay attention to the charge wire coming out of it. That will often be too small and can cook from excessive draw. Amps should wire straight to the battery with individual circuit breakers, and not to other power sources in the car.

The longer you listen to music at elevated sound levels, the more you tax the battery and charging system. That is, if you commute a distance, the voltage level in your battery may begin to drop if it cannot keep up with the "total" draw, including A/C and headlights and such. As voltage drops, the amp is more likely to clip (distort) and damage your speakers, usually the smaller ones first. See on your amp spec sheet that most are rated at 14.4 volts or thereabouts, which is what the alternator is putting out while driving. As this dips down, so does the ability of the amp to maintain spec. Big systems should have a volt meter that is wired at the amp(s) so you can see what it/they are getting fed.

Tuning the system for "flat" sound reproduction? I believe it's another gimmick. The fact is that humans all hear differently and have different preferences in *what* they hear. I have seen people pay for acoustic flattening and hate the results. If the system is properly designed to start with, then fiddling around with EQ settings in the deck should suffice.

There is much more to all this, of course. I stay out of the sound newsgroup because everyone is an expert even if they don't know WTH is going on. All my observations come from experience. I hope this gives a little insight to anyone building up a system.

Outstanding post, CJ. As a musician, I can attest that all of this is true. Everything that applies to mobile stereo (except the 12-volt stuff) applies to guitar, bass, keyboard, and PA rigs as well. It's all valid sound theory.

Witness the Ampeg SVT bass guitar cabinet:

Most bass guitar cabs use 12" or 15" speakers for depth, but lack punch especially in the midbass region. I used to play with a guy who used two SVT cabs on stage; his rig had both punch and depth.

Before I ever heard the SVT, I seriously doubted whether the 10s would hold up to the low bass at high power. After he played for a few minutes, all doubts immediately disappeared.

Joe Calypso Green '93 5.0 LX AOD hatch with a few goodies Black '03 Dakota 5.9 R/T CC

CobraJet wrote in news:220220052125416125% snipped-for-privacy@streetracer.sfv:

*accurate*

against

windmilling

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length

outside

material.

"quality"

upgraded

charge

Glad you liked it. I think everyone else thinks I'm nuts. Quiet. And I didn't even get into stereo imaging or tweeter placement.

I see they use 30-oz magnets on their 10's. Most of my car stuff ran

60-oz for 8's and 75 for 10's. This is why, with a good amp, you only need one sub. I like DVC's a lot.

I agree with Joe. Great post. I'm not an expert, but an enthusiast and a bit of an electronics geek. I'm more into digital tinkering than analog though... I don't like math all that much. ;-) I design some small things, and understand basic AC theory.

Definately does. I've always tried to correct guys who spoke about how many watts their speakers could handle claiming that their system produced that amount of power. Then I see the Jensen amp, and just start laughing wholeheartedly.

And as noted on most spec sheets, THD is either measured at a load greater than 1 ohm static, or if they dare measure at that load, gets significantly worse on all but the best amps. My grandmother has a set of Carver Silver Seven-t home amps that will deal with a 1 ohm load, and I'm sure do just fine, but I don't want to know what my grandfather paid for them.

Great analogy.

I tend to underdrive not only my speakers but my amps as well for the reasons of sound clarity and longevity. While this isn't always a guarantee, I understand, it helps. In the aforementioned system that I put in my old hatchback (which has carried over to a rice-rocket winter beater), the subs were hand-me-downs, cheap 12" MTXs at 4-ohm. The amp is a mono amp designed to run two 4-ohm speakers. The box is sealed. I don't like the sound of a bandpass. I'm not real sure about the benefits of a port hole, I've heard a sealed box produces tighter bass at a reduced level in sound, which I'm willing to accept.

This makes sense, and I've heard some pretty impressive things come from relatively small drivers. On those Carver amps, my grandmother had a pair of Polk Audio towers. They made amazing bass, despite only having 6" drivers (albeit three of them) in a room that is quite soft by most standards. Because the room was this way, though, there were holes in the sound which I'm sure could have been tuned out.

I definately have problems with my 12s concerning big gaping holes, especially in the sub-bass and mid-bass regions. I don't have the cash to spring for a bunch of small drivers though. Can you explain the phasing a little better? Are you talking phase shifts of a degree or two to match the sound being produced by a speaker located farther from the ear, or is this something else?

I've only been able to cover up the mid-bass problem so much with the other speakers. The Eclipse's current situation is much like the one I described for my Mustang, only instead of 6 amplified coaxial channels, I have a 45x4 (RMS) amp driving a pair of 3-way coaxial 5x7's in the rear and a set of components up front... 6" or so in the door near the ankle, and the dome tweeters mounted behind the mirrors. They're facing toward each other, but go farther toward imaging from what I can tell.

Silly kids. The Clarion was bought to do the job it does. It doesn't have a huge inflated rating, and I know there are much better out there, but it does its job pretty well and doesn't pretend to be something it's not. I've never hurt it, even after using it at home with a power converter in my dusty house... with those same 12" subs. That whole setup's followed me for years...

All good advice... that many seem to overlook.

I agree, however, many people tend to end up overdriving with the EQ and distort the preamp signal... which just spells disaster for the rest of the system. How many times have you seen a guy crank the bass all the way up on the EQ thinking he's wringing one more ounce out of an already uneven system?

I've always been under the impression that if you're going to tune with the EQ, tune down from flat, or at the most, tune only very slightly up. Setting the amps at max volume before clipping with the head at max (on a fully outboard-amplified system, that is) ensures the system is never taxed to the point of clipping only if the EQ settings aren't tweaked way up. I don't have a problem with tuning to taste either... but if it's done to the point that you're causing distortion at the signal's source, then there's an issue.

I'm curious to hear your ideas about staging and tweeter placement. I like sound loud, and clean, and even... but only know enough to be dangerous and impress only those who are mostly clueless. While I'm typically happy with the results, I know they could be better. I'm also curious about what sub arrangement I should put in my winter rice-rocket to match the rest of the system well. I'm considering designing a custom box/amp rack for the hatch area.

JS

CobraJet wrote in news:230220052017547974% snipped-for-privacy@streetracer.sfv:

Saving that for next week?

With 8 speakers, they can get away with using only 30-oz magnets per speaker. Anything more for that rig would be overkill.

Also of note, that cab is split inside. The top 4 speakers are separated from the bottom 4.

Joe Calypso Green '93 5.0 LX AOD hatch with a few goodies Black '03 Dakota 5.9 R/T CC

"JS" wrote in news:D4dTd.36460$s16.20556@trndny02:

Ooh, nice stuff. State of the art back then.

Ported boxes (also called bass-reflex enclosures) will give you a slightly deeper bass, assuming the box is the correct size internally for the speaker and the port is "tuned" to the speaker/box combo. They're slightly more efficient than sealed boxes as well. Sealed boxes, however, will provide a more "accurate" sound.

I believe CJ's reference to phasing refers to wiring the speakers properly. An important assumption is that all the speakers in the room (or car) are wired in phase.

Speaker cones move back and forth to push air. The idea is that all speakers should be pushing together so that one speaker isn't pulling while another is pushing. If you hook up a battery to a speaker and watch the cone, it'll move either in or out depending on which way the battery is hooked up. An out-of-phase speaker will work against the others, thus cancelling out some of the content you hear. It's pulling while the others are pushing.

To help with the midbass, you might try increasing the low end to the

5x7s and 6s but put a hi-pass filter on them all. If you use a 150Hz cutoff and increase the bass level (remember to compensate on the sub level) it might sound a bit better. Might be worth a try.

Great point. Lots of guys run their front ends so hot that what's hitting the amp is nothing but clipping and distortion. D-oh.

Personally, I like tweeter placement up high for imaging. Some people like the high end content to come from the front, but I prefer it from all around.

Optimally, I'd go with a 4-way system, with each component driven by a separate amp. Tweets, midrange (4"), midbass (6-1/2"), and subs (4x8"). 2 cents.

Joe Calypso Green '93 5.0 LX AOD hatch with a few goodies Black '03 Dakota 5.9 R/T CC

Wow had to read this a few times:) You're totally right on this, I should have said 2800 Max with about 1600 RMS. I have a voltmeter hooked up just in case, but the two 800s arent taxing the electrical system a whole lot.

As far as depth, Im planning to resolve that later on, with some small drivers.

On the bright side though, I did manage to embarass a couple wanna-be gangstas in the neighborhood. Two days after I was done playing around in the driveway, what do I see but them out there with a walmart wiring kit and the biggest $50 sub/box combo from best buy that would fit in the trunk of their 88 caddilac boat.

Havent been able to stop laughing for the last three days straight.

Yeah, they sounded great. Modeled after the Silver Seven tube amp (and made back when Carver was still with the company), they even required a bit of warm-up time to really sound great, even though they were solid state. They could handle everything I ever threw at them, and I had quite a few occasions to play with the system. Carver preamp and tuner, Yamaha natural sound CD player and cassette deck. My grandfather loved his toys.

That's how I remember hearing how it went. As I didn't have the capabilities to tune the port, and I preferred clean sound over loud noise, I left it sealed.

Understand the phasing thing... figured most people who really knew how to wire a system understood that. When I was 17, I bought a JVC receiver and tried to hook it up in my room. I was sure I hooked it up right, right phasing and all, but couldn't get over this huge hole in the center of the room where the sound dropped out. I tried EQ settings and surround settings to no avail, and after I surrendered that I might have hooked it up wrong, I saw that the left speaker was wired backward. Everything was wonderful after that, and I definately learned how a 180-out-of-phase speaker could really mess up a system. That's the same technology they use in "noise cancelling" headphones and what not... just mic the outside sound and phase-shift it.

I'll have to check my amp settings again, as I don't have an active crossover wired into the system at this point. The 4-channel will let you hi-low-full-pass the fronts and rears separately.

The fronts have a passive crossover designed to work with those particular components, so I'm sure the 6s are set low-pass there, but I'm not sure if they're high-passed as well from the amp. I'll check and report back The rears may in fact be high-passed, but I'm not sure where the cutoff is set at.

In the Mustang, I had 6 amplified coax speakers, so I had the tiny tweeters in the dash, door, and rear hatch area, and all were aiming at the center head area of the front seats. It was more than enough. I mounted the little domes in the Eclipse behind the mirrors to get them up high. I think it sound ok. The 5x7s also have the tweeters in them and are aimed forward. I'm not sure if that's the best placement or not.

I already bought the components up front, and feel I have a decent mix with the 1" dome tweeters, 6" round door speakers, and the three-way 5x7's in the back (plus I don't have the cash to change it all out now). I have a couple of holes in the sound, mostly in the mid-bass region because of the 12s. What kind of power would you run to all of these components for a decent balance?

JS

"JS" wrote in news:_HoTd.31058$ya6.1530@trndny01:

Cool. I also liked the McIntosh stuff. Still do.

There ya go. With enough power, a sealed box can sound awesome.

This is how some bands did feedback control when they played live on stage. I've seen lots of pictures of Jerry Garcia of The Dead with a pair of mics on a stand. They were wired together out of phase to cancel out all the ambient noise that hit both together; Garcia sang into only one. Neat trick.

If you're running a sub, you should have fronts and rears on hi-pass only. Ideally, the crossover point for the hi-pass should be about the same as the crossover point for your sub. You'll get a bit of overlap due to the slope, but you don't want to have a gap there.

Assuming you have adjustable crossover points for the sub and/or hi- pass, this is something else you can play with to improve that midbass region.

As you say, the components have their own passive crossover between the tweeter and the woofer, but the entire component set should be hi- passed as well if you're running a sub.

Whatever sounds good to you is the best placement IMO. Sound is a very subjective thing.

Given your setup, your most economical choice would be to leave the

45x4 amp running the front components and rear 5x7s with a hi-pass filter. Depending on how the subs are wired and the impedance, you should probably run anywhere from 200w RMS for the pair on up.

All in all, I think the key factor in a setup like that (i.e., no midbass) is to play with the crossover points. To compensate for the lack of midbass, you could hi-pass the main speakers at around 125Hz to allow them to reproduce midbass freqs, and cross the subs at around

250 to let them carry some of the same midbass freqs as well. You'd have an overlap around the low-midbass point which would certainly give you a boost at around 100-150Hz. Might not be the cleanest sound, but it may sound better to your ear.

Do you have any EQ control on your head? If so, you could bump the

150-250Hz a few dB to see if that helps.

Joe Calypso Green '93 5.0 LX AOD hatch with a few goodies Black '03 Dakota 5.9 R/T CC

Maybe.

True. You guyses don't have to deal with a 70-db noise floor.

I'm gonna guess cutting down the refraction area keeps back waves from coloring the sound. Just a guess.

CobraJet wrote in news:240220052025349565% snipped-for-privacy@streetracer.sfv:

I'll look for it.

depth.

On a live soundstage it's anything but. If you're pushing it, distortion from a rig like that probably reaches around 25% if not more. But that's what gives it the "edge".

You're probably right about the back waves, but I don't think it's to prevent sound coloration. I think it's for efficiency. On a live rock soundstage, these guys are pushing over 110-120 dB easy. The band is louder than a jet plane taking off. Cabs like the SVT are designed to produce maximum SPL with a kick-ass tone at probably 50% or higher distortion levels. It's not uncommon to push a rig to that level of distortion during regular playing.

Joe Calypso Green '93 5.0 LX AOD hatch with a few goodies Black '03 Dakota 5.9 R/T CC

Ah yes, Jensen. I started out in High School installing Lear Jet and Craig 8-tracks with Jensen tri-axials. That rocked in '73.

I have a pile of Carver stuff from my dad's estate. Great stuff. Might even hook it all back up soon when I move into my other building. I pity the neighbors.

And murder on the crotch, too.

Sealed boxes are great. My preference, with a good amp.

Years ago, Harman Kardon had a speaker that incorporated three

7-inch (European size) bass drivers. I think it was the Citation Eleven. It, too, was impressive.

Joe answered this already.

All the time. People are bass crazy.

Good approach.

I'll get around to it. I was hashing it around in my head today, trying to figure out putting something you sense into practical terminology. Not easy.

BTW, my favorite reference CD remains to this day The Best of Stan Ridgway, "Songs That Made This Country Great", released in '92. If the name doesn't click, he was the lead man for Wall of Voodoo. Lots of different track styles and instruments. The bass played by Louis Cabasa on "Salesman" will readjust some attitudes on a good stereo. Worth digging up a copy.

And one of the reasons I stay away from live performances. It just doesn't make it for me. I can feel the damage =80