Driving db6500 Components in Convertible

fierrosc

Well I finally did it, as most of you suggested, I scrapped the Mach 460 in my 96 mustang convertible.

I originally started by scrapping the tuner / tape player and cd player and replacing it with a Panasonic MXE CQ-HX1083 CD/MP3/WMA head unit using a Scosche OEM Amplifier Integration adapter to tie it into the stock Mach460 amps and speakers. Although now I can listen to MP3's, the system sounds no better or worse than it did before.

My next step was to scrap the speakers and install two pair of Polk Audio EX3550's (5.25) components I got from Crutchfield along with the head unit. Since there website told me that 6.5" woofers would not fit in the car, I figured it would be less of a head ache to run 5.25's, besides they were on sale for $100.00 off each pair.

I installed the front door pair using a Scosche 6x8 adapter for the woofer, a home made 2.5" to 1" adapter for the tweeter made out of 1/8" hardboard ($2.00 home depot) traced from the stock 2.5" tweeters with a 2" hole cut out of the center, and crossovers using zip lock and bubble wrapped inside front door panes just behind door handle.

I started installing the rear pair and after removing the rear side panels found out that the stock rear speakers, at least on a Mach 460 convertible are 6.5", the same size that Crutchfield said would not fit in my "96 Mustang Convertible with Mach460", So I yanked out the front EX3550's components and started all over with two pair of db6550 components.

The Polk Audio db6550 component speakers were just made for this car! The front tweeters fit perfectly when flush mounted on a 1/8 hardboard adapter traced out of the 2.5" stock tweeters with a 2" hole in the center. No clearance problems when the sail grill is replaced. I did have to drill out the speaker wire hole to make it big enough for the wires attached to the tweeters. The 6.5" woofers fit in the front door with the Scosche 6x8 adapter plates even better than the 5.25's did. The crossovers fit snug right inside the door panel just behind the door handle and can be accessed by removing just the door handle panel (not the entire door panel). The speaker wire that comes soldiered to the tweeters is long enough to make it from the tweeter enclosure to this crossover location which was not the case with the EX3550's.

The 6.5" woofers drop right into the rear side speaker enclosures stock location and the tweeters worked out nicely with the same adapter plates built for the front ones. There is an excellent location for the rear crossovers, just below the rear woofers, screwed right onto the rear speaker enclosures. I did have to do some minor drilling into these enclosures to run all new speaker wires as I didn't want to remove the stock wires. The speaker wire that comes soldiered to the tweeters is long enough to make it from the tweeter enclosure to this crossover location.

So now I'm back to square one, I've got the basic components that sound as good as a Mach460 with support for MP3/WMA, CD-Changer, and Sirius Radio. Now I need to start thinking about putting some mustard behind these db6550's as well as a sub in the trunk. I'm going with Polk Audio for all my speakers including subs and going with Rockford Fosgate for all my amps, so no other brand suggestions please.

I measured my stock alternator at idle it's doing 14.6 volts and rated at 120 amps. So doing the math, according to Crutchfield (120 amps X 40% ) I've got 48 amps of reserve power for my stereo. This doesn't seem like a lot of amps to work with given most of the Rockford's are rated at 30, 40, and 50 amps!

So I'm thinking about something like this...

Rockford Fosgate Power 551x (70w x 4) = 280w on Polk db6550
Rockford Fosgate Power 501bd (300w x 1) = 300w on Polk MM2104

... so doing more Crutchfield math 580w x 2 / 14.6v = 80 amps that I'm going to be pulling, so I've got to be missing something here otherwise this sounds like to much for my car to handle.

Any other suggestions for amplifier's pushing two pair of Polk db6550's and a single Polk mm2104 sub are welcome.

Thanks in advance...Chris

PoweredByDodge

Ignore crotchfield math - buy their stuff, but ignore their math.

Do Vinnie math, also called "Differential Stupidity"... with such equations as...

' Dodge + lots of audio = Boom '
and
' Boom^2 / 3 = still Boom ... by the law Boom=Infinity '

anyway.

No... you've got a 120A alt? great... you can run a shitload of stuff off that.

Make sure you've got a nice 900 - 1100 cold cranking amp battery under the hood - ditch the factory battery. Pick up a 875 cca Die Hard, a 900 cca Energizer, a 1,000 cca Exide (Napa is the only ones who sell them i think), or the biggest one Interstate makes, and call it a day.

you'll run about 69 bucks to 89 bucks for that (the energizer is 69, the die hard is 89, everything else is in between).

with that you can safely run something like an RF 1000.1bd and an RF doing like 75-100 x 4 to your highs.

that'll be about 130 - 140 amps tops... but that's at peaks... when the "bada bing bada boom" hits for a brief time... so u get a heavy drain that's 20 over your alternator, and your battery picks up the slack, and then in the time before the next boom your alt recharges the little bit that was drained from the battery while still keeping supply to your ignition system and ****.

all this takes place in a very very quick amount of time, fast enough that you will probably never see that voltage needle move.

i run 4 large amps off two batteries and a stock alternator, i cant see u having trouble, unless you drove a small car with a small alt.

Jstas

Um, the 40% deal is maximum load. You will get that 60% load rating when you add all the amperage of the entire system up and subtract it from the alternator's rating. Most of teh time though, that is not the case. For example, your power seats do not have a constant amperage draw. Neither do power windows or mirrors. That can give you another 20% in reserve right there.

But, like PBD is trying to say, you don't draw power from your alternator. You shouldn't actually, not without a voltage regulator rated for the current draw you are trying to support. You draw power from a battery which is capable of supporting your current draw. The only thing you have to really worry about is if your alternator is capable of replacing the power drawn from your battery. A typical car charging system can support around 60-75 amps of draw. Beyond that, you can start having problems without a beefier or even second alternator. Unless you are powering huge amps with a pile of power, I would not worry about it.

You can do the math if you want but it is not accurate. You can't go by wattage ratings. D-class amps will make that math mis-proportionate because they are more efficient than AB class amplifiers. What you should be looking at is the fuse rating on each amplifier. There is no possible way, short of catastrophic failure, that an amplifier will be able to draw more amperage than it's fuse rating. Mainly because if you try to push 22 amps of current through a 20 amp fuse, it's gonna pop faster than Orville Redenbacher's!

fierrosc

Thanks for the reply on the car's ability to support the amps.

Now onto power wires, fuses, and distribution blocks. Both the Rockford Fosgate's ship with 50 amp fuses. so I think I'll need to run about 10-15 feet of 4 awg from the battery with a 100 amp inline fuse and then distribute the 4 awg in the trunk with a dual 50 amp distribution block with 4 awg into the RF amps.

Problem is I can't seem to find a distribution block that goes from 4 awg input to two 4 awg outputs. Seems like they are all 4 awg inputs to two or more 8 awg outputs.

The distance from the distribution block to the amps won't be more than 4-6 feet. Should I run 8 awg from the dist. block to the amps with a 50 amp fuse on each ?

What about a capacitor ? If I decide to put one in, what size do I need ? Will a 1.0 farad 20 amp do the job ?

Thanks agian...Chris

sntnsupermen131

http://www.sounddomain.com/sku/ROCCPGFDU2
im running 1 4awg input and 2 4awg outputs on this exact same fuse distro block--bought from the same place
cheapest one i can find
plus its rockford fosgate so it matches your amps
as far as going 8awg...go 4...its better
especially if youre pulling 500 watts
as far as wiring
www.knukonceptz.com
if you find cheaper power wire than that of that quality i will be amazed
all my power wire is from them
now speaker wire and rca cables im a bit more picky...
but power wire for the most part is power wire...it has the same or more amount of strands in it as rockford fosgate or the similar brands
and caps...
id recommend a 1 farad cap
they have them at www.ikesound.com for really cheap
dont bother with digital voltage readouts unless you think its worth $20 to show off to your friends...thats about all it does...
caps are caps as far as whats good and whats not
we had a guy come on here one time and he said that the best buy guy he was talking to said that this particular brand was the only good brand and that the other ones were half filled with sand to make them feel heavier...
if someone tells you that....slap them...they deserve it
i have 2 rockford fosgate 1 farad caps....they look nice
but the lightning audio ones are $30 cheaper and dont look to shabby
if you want to get rf caps...i think it was $120 at ikesound.com for a 1 farad...or something like that
-Cody

MTXMAN

my Roadshop Manager at CC said that he saw 3 brands of caps cut down the center, streetwirez and 2 others, he said that the streetwires cap had more of whatever they make the cap out of and the others had more fill... just what he told me he saw... btw this was long after CC stoped carying SW in favor of Monster cable... of course he was normally full of **** so who knows ;D

PoweredByDodge

streetwires caps actually have a different type of dielectric in there.

its more 'gooder' electrically... less 'gooder' if it pops and goes seeping out into your car (or on you).

lightning audio's dielectric is the most environmentally friendly.

that's pretty much based on word of mouth and a little bit of talking to the mfg's.

streetwires makes a good cap.

as far as "stuff" in there.. versus "fill".

a cap is just a rolled up mess of tin foil (well not tin, but something foil). with a dielectric between the rolled sheets. depending on the material used for the plates (sheets) and the material used as dielectric (liquidy fill), you may need more sheet and less dielectric, or more dielectric and less sheet in order to achieve 1 farad of capacitance. its not a big deal what the proportion is... its more the material.

however, ideally, the closer the plates, (the more the foil in a standard sized 1 farad tube), and the more potent (for lack of abetter word) the dielectric, the better more efficient the cap will be, the more responsive, the quicker to charge and discharge, and hopefully the less the internal resistance.

but design is more a question for somebody who's actually put one together, as materials rarely act ideally, and certain things like "what if it gets smacked on the side and dented a little" have to come into place when designing it.

PoweredByDodge

oh and as far as fuses.. if you have two amplifiers with 50 amp fuses, put like an 80 amp fuse on your main power line... you'd want the glass fuse in your power line to go before the fuses on your amps go. you're not going to see them draw 50 amps at a snap ... usualy half or more, so 80 would prolly be perfect. that way if one acts up, it'll pop fast.

fierrosc

Hey, thanks for the tip on the fuses, it's be much easier to replace the one under the hood than the ones that are going to be barried behind the rear seat.

That also save's me from upgrading to an ANL fuse as, the dual amp installation kit I got from thezeb came with a AUG fuse holder and those fuses only go up to 80 amps.

About the distribution block, does it matter much if I use a distribution block with two fuses, or just a regular ground distribution block (without fuses) and have inlines fuses in between the block and the amps ?

If I go with the inlines I can probably but them right under the rear seat as they are less bulky and the rear seat on the mustang convertible pops right out with a couple of clips.

Thanks...Chrs

Jstas

Personally, I'd put the fuses in. It's much better to blow a 2 dollar fuse than it is to blow a 300 dollar amp. If you leave the power wires going straight to the amp after the 80 amp fuse, you are getting the full bore of what that 80 amp fuse will allow. A 30 amp difference will destroy that 50 amp fuse and a surge that large could potentially damage the amplifier itself. Even with that 50 amp fuse.

If you go with a fused distro block, you can put a pair of 50 amp fuses into the block and then run your power wires to each amp off of that. That way you have a total amperage protection with the 80 amp fuse and you have individual amperage protection with the 2 50 amp fuses. Like I said before, tis better to waste a 2 dollar fuse than a 300 dollar amplifier. I'd rather fork over the extra 30 bucks for the distro block and fuses than fight with the amplifier manufacturer to replace an amp that died pre-maturely. 30 some odd dollars of insurance, ya know?

fierrosc

Jstas,

Oh I'm definitely going to be putting all three fuses in, no question about that...

What I wanted to know was if it made any difference to go with a two fuse distribution block or a non-fuse distribution block followed by inline fuses (one fuse per amp after the block and before the amps)

...Chris

MTXMAN

i don't think it'd make any difference at all other than ease of install and cosmetics, go with what suits you on that one

Jstas

Yeah, doesn't really matter there. In line or distro block, doesn't matter really. Which ever would be easiest for you.

fierrosc

Well I orderd the Rockford Fosgate 551x and 501bd amps along with $100.00 bucks worth of 4 AWG, Distibution Blocks, Fuse Holders, Fuses from SoundDomain. Wow that **** adds up fast and I still need to upgrade the battery and get a cap!

I also ordered a 10" MM2104 sub for the trunk and would like some advise on this subject. I'm going to place the sub in the center of the trunk and have it fire towards the rear of the car. This will leave enough space on both sides of the sub box to mount the amps, like this...

|||| 0 ||||


...in case your wondering, it's a 42" wide box, but with a single .66 cf chamber in the middle.

Is mounting the amps directly on the sub box a good idea or is the sub going to shack the amps to pieces ?

Given that this is not plan stupidity, I could probably get two subs in the trunk if I fired them down, leaving a clean surface for the amps to be mounted on. Is this a worse idea, does it matter where if fire the subs as long as they hit something solid ?

Thanks...chris

MTXMAN

so it's a box for a single 10 but it's 42" wide??? that's an odd box... the only problem that comes with mounting the amps on the box is ease of theft. it should cause no problems with the amp shaking. have fun

PoweredByDodge

... wait - you bought a 500 watt x 1 at 2 ohms mono amp (that will actually do like 600 x 1 at 2 ohms or more) for a 4 ohm sub -- so u'll only get half that - like only 300 watts to the sub.

if you just wanted 300 watts you should have gotten like a 301S or a 401S (300 or 400 x 1 into 4 ohms) -- it woulda been cheaper, and cleaner.

fierrosc

Yeah it's not really a 42" long box, just didn't know how else to discribe it's actually something like a rectagle on the bottom and a triagle on the top, the chamber is only 11 h1 (front) x 5.5 h2 (back) x 18.5 wide, but I'm thinking about putting a larger front 12.5 h x 42 wide face plate on it and float the amps on each side.
____
/ |
|___|

The whole thing will be bolted down from inside the passenger compartment behind the rear seat (where the old stock amps used to bolt down). So they'll have to take each amp individually, probably be easier just to take the whole car.

Thanks...Chris

fierrosc

PoweredByDodge,

Your wrong about the 501bd, it's actually a 300 watt @ 4 ohms mono amp, that you can run at 2 ohms and get 500 watts.

Anyway the 301s and 401s are from the Punch (with a 12dB/octave ) line not the Power line (24dB/octave), so I actually considered the 351s and 451s two channel Power amps to run the sub, but the bd amps as the name implies "bd" are actually designed for subs, class B effeciency with class D power, so they are going to be more effecient and cleaner.

So, yeah about twice the price for the bd over the s models, but were only talking about a buck and a quarter to a half, not that big a deal.

...chris

PoweredByDodge

efficient is not clean.

efficiency implies you get more wattage on less current draw... this mean less "****" gets filtered.

in CLEANEST AMPS ON EARTH are class A-biased Vaccuum tube amps... they have an efficiency ranging from 25 to 40 percent.

class AB 2 channel amps range in the 65-ish to 70 percent range and are the "standard" in car audio.

class D's (BD / T / D) are about 80 - 85% efficient and they are (in comparison to AB 2 channels) dirty as hell.

the only reason for buying a class D are as follows

1- you run a lot of subwoofer power and are scared of killing the battery / alternator.
2- you need a lot of subwoofer power and dont have the money for a class AB (a 1500 watt class D can be had for 300 - 400 bucks, same thing in a class AB of similar "brand name" is about twice as much).
3- you need to drive a very low ohm load (D's tend to drive 1 ohm or 2 ohm loads better than the mainstream class AB's- which are usually only 4 ohm stable... however some more non-mainstream ones are built with varying bridged load options).

... anywho - the only good thing about you buying the BD 500 is that you can go and add a 2nd subwoofer (or a dual 4 ohm voice coil 600 watt sub) some day without buying a new amp. if you plan on keeping with one 300 watt single 4 ohm coil sub then you'd have been much better off with the power series 400 x 1 amp (451S).