Printer Friendly Forum Posts - High Current Amp ?

ok im doing a system in my friends BMW 3series
now im are going to put either 2 or 3 10JLW6's in the back and were looking for a good amp to push them
now first question
-- does a high current amp require that you change the altenator???
--what amp would you recomend to push theses subs to get full power from them???
pLEASE LET ME KNOW
THANKS

It really depends on the amp and its current draw as to whether you need to up the alternator. The amp is going to be the second or third thing to think about in the car, the first two things should be the box design and how you are going to get the sound into the cab of the vehicle.

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If i was looking to design a jl system, which i love jl products. I would recomend 2 10 jlw6v2's instead of 3 jl w6's you will be alot happier with the sound quality and spl levels. As far as an amp i have hooked up 2 of these sub config's ina vented box to a rockford 800a2 and it sounded very nice, it was able to push 148.8 in a standard car. and 151.3 in a hatchback with some power mods basically a 5 farad cap and a yellow top under the hood..let me know if you need help with the box i do still have spec's for these boxes

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2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR
2007 USACI World Champion
2007 World Record
2006 USACI Finals 2nd Place

yeah i told him to too go with the w6v2 but he has the w6 already thats y he wants to keeep them

als o im going to have the subs fire in to the car from behind the seats
also if u can help me design a box that would be kool.
im not to sure what amp he wants to get but if u have a good suggestion please let me know
thanks

i wouldnt recomend firing the subs into the car, with a vented or ported box it is best to let the repercussion off the trunk lid return to inside the car i will try to draw up a box and post today

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2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR
2007 USACI World Champion
2007 World Record
2006 USACI Finals 2nd Place

ok then what if i hvae them fire to the trunk and put a plexi glass back on them so you can see the magnets how thick would the plexi have to bee??

also the box you are going to draw will it fit tight against the seat ina 02 bmw 3 series

also if you could maybe email me the plans and letme know some otheroptions i might have
thanks
bboy411@aol.com

I would go with a 3/4 or 1 inch plexi..but plexi gan be expensive if you are buysing sheets from stores like home depot, try to find some old boxes for salvaging plexi, try local pawn shops they normally have boxes laying around if you cant find any i can get a good sheet off an old box for you

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2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR
2007 USACI World Champion
2007 World Record
2006 USACI Finals 2nd Place

only thigi really want to clear up is how much of a difference will firing the subs in to the car and in to the trunk make a difference in sound and quality byt hat much???
thanks

ok i made a little mistake he had told me that he had w6's but i looked today and he has the w0's 4 ohm
now im thiking of using 3 of them facing the trunck which amp and box size do u recomend now
also remember u said dont face them into the car.
i had this crazy i dea that face 2 subs to the trunk and 2 subs facing the inside would the y cancell each other out
tell me what you think
thanks

Well, the 10W0-4 ohm model can handle 125 Watts RMS power each. They're single-voice coil, so the only configuration that really makes sense is to parallel them all together for a 1.33 ohm load. You need an amp that's 1-ohm stable and puts out 200-675 Watts RMS. With the relatively low sensitivity of the 10W0-4 (85.5 dB/W-m), I'd tend towards the high end of that range. A 2-ohm stable amp might work with a 1.33-ohm load, if the amp is rated conservatively. I think JBL has a 600-watt mono amp that's 1-ohm stable, and there are probably several other brands/models as well.

Scott Gardner

with 4 4ohm subs you would have a even 1 ohm load..therefore yes you would need a 1 ohm stable amp, but as far as 2 inside and 2 in the trunk you would end with 2 diffrent frequencys because of repercussion and you would also have a very minor diffrence between when the waves get to the front of the cab also causing some canceling, i would go with either all 4 rear firing in a sealed box or all 4 firing at the trunk lid in a vented box, i was able to do 4 in a civic and am currently designing 4 hatchback all vented for a guy right now i can give you some specs if you would like.

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2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR
2007 USACI World Champion
2007 World Record
2006 USACI Finals 2nd Place

He was talking about using three of them, that's where I got 1.33 ohms. But I agree with you that he's better off facing all of the subs (whether he ends up using three or four) in the same direction. There's been a lively discussion on rec.audio.car about the effects of rear-facing versus front-facing subs, including some SPL graphs that show a pretty significant difference. So to avoid unnecessary cancellation, I'd try to a) locate them as close together as you can, and b) face them all approximately the same way.

Scott Gardner

ok so i think im gooing to face them into the ttrunk .the only reason y i was going to face them in the car was for asthetics only but if its going to hurt the sound ill rather do it the other way.. also you thiink i can get all 4 in the trunk of a 2000 328ci. he diesnt want the box to big after the whole install. he still wants at lest the front half of the trunk for storage and stuff.you think that you maybe can draw something up for me?? or help me out with a plan.also i cant have the box reach the top of the trunk for future plans so it has to be about 6-8inches from the top
thanks

Did you decide on a ported or sealed box for the four subs? If you go with a sealed box, you'll need between 2.0 and 3.6 cubic feet of airspace, AFTER you've subtracted the volume of the subs, bracing, etcetera. If you go with a ported enclosure, the requirement jumps up to 3.6-6.0 cubic feet. That's getting to be a big box for the back of a 3-series Bimmer.

Have you measured the available space yet? If the customer wants 6-8 inches free on top of the box, you can't put the four subs in a 2X2 array - it'll probably be too tall. You probably can't line them up in a row, either, because the subs themselves will occupy 44" of width. If you chamber the box to give each sub its own airspace, that's three dividers, plus the left and right wall, for another 4" or so. Unless you can stagger them or come up with another creative arrangement, you may be stuck trying to put 10 pounds of dirt in a 5-pound bag.

Scott Gardner

thats what i was telling him. see my concern is he wants it to hit hard and i dont know if i c an get what he wants from 2 jl 10w0 but what do u think;
if i do go with just 2 is it better to go with sealed or vented what do you think
also he was looking at this amp what do u think for these 2 subs
Peonix gold amp

Well, I'll start off with the amp. Looks like a good amp, but 600 watts into the 2-ohm overall load you'll get from two of the 10W0 subs is overkill. Never hurts to have too much power, though - he may want to upgrade subs in the future and the amp will be ready for him.

I wish I knew what your customer meant by "wanting it to hit hard". Putting 250 Watts RMS into a pair of 10W0s, he may be pleasantly surprised. In my old Jetta, I was putting about 375 Watts into a pair of JL 12W0s, and it was plenty loud for me, even in a sealed box. My wife's car has a single 12W0 in a large sealed box, being driven by 100 Watts RMS, and it's loud enough for her. Granted, her Toyota Paseo is a good deal smaller than a BMW -series, but she has half the speakers and less than half the Wattage that we're talking about with the Bimmer.

I'd try to talk the customer into just using two of the subs, and building a nice ported box to get the extra SPL. You'll have to be careful with the gain on the amp, since the ported box won't protect the subs as well as a sealed box will.

Scott Gardner

well its my friend and i know he wants it to sound loud and clear .he wants to make sure hes heard like a block away u know hat i mean lol
as of now we are going to use the w0 but he wants to sell all four of them and i told him to get 2 10w6v2's and i have to figure out what amp and what type of box to do?
can you help me out with the two senerious
either using 2-3 w0 in what box and what amp

or using 2 wv62 in which box and amp
thanks f or your help

The PG amp you linked to earlier still sounds fine, or he could go with something larger now that he's considering the W6 line (See below). Whichever way he ends up going, either with the W0 or the W6, he'd probably be happier with a ported box, if he wants serious SPL levels out of two or three tens. The 10W6v2 would really be the best bet, since they have so much more power handling (400 WRMS) compared to the W0 (125WRMS). Here's a link to the data sheet for the W6 subs:

https://www.jlaudio.com/subwoofers/pdfs/W6v2_MAN.pdf

The only drawback to the 10W6 is that it's got dual 4-ohm voice coils, so with two of the subs, your only real choices are 1-ohm overall or 4-ohm overall impedance. The PG amp we're talking about makes max power into 2 ohms, which wouldn't do him any good in this case. Better to look for something that's 1-ohm stable. Here's a possibility from JBL:

https://tinyurl.com/2ydoo

It's 1200W into one ohm. That's more than a pair of even the W6's can handle, but it will give him some headroom and more power if he wants to upgrade later.

Good luck,

Scott Gardner