new system set up Qs.

[Bishop]

hey guys,

just have a few questions. Im setting up a new system, i have this,
http://ecominet2.alpine-usa.com/pls/admn/item_info?p_item_name=MRP-F200&p_category=40&p_subcategory=120&p_main=10&p_more=y

powering 2 of these
http://www.jlaudio.com/subwoofers/12w0.html[/url][url="http://www.jlaudio.com/subwoofers/12w0.html[/L]"] (http://ecominet2.alpine-usa.com/pls/admn/item_info?p_item_name=MRP-F200&p_category=40&p_subcategory=120&p_main=10&p_more=y)

I have the amp installed, and had the subs running, but they didnt seem to make very much bass and made very little difference. The amp i have is a 4x75w or 2x180w amp. I have the 2 12" subs in differnt boxes, so they dont need to be bridged right? I have the subs connected to channel 1 and 2. Do I have to do anything to get the channels to 2x180w and not 4x75w? I think i have the settings on the amp correct. What am i doing wrong? Or did i just buy a POS system?

any help would be great,
Bishop


edit:fixing links
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[EWF]

First thing you should do is to test each sub individually. Listen with only one connected at a time. If both sound fine individually, I'd bet on phase cancellation as your problem. In this case you could have one sub wired backwards compared to the other - each would sound fine individually, but when you have both connected, one sub will be pushing while the other is pulling, causing one sub's waveform to be cancelled by the other. If they don't sound okay even when only one is running, try moving the sub around in the hatch. You'll be surprised how much the bass level can change at the driver's seat just from moving your sub around in the hatch. If that doesn't help, check your connections and your amplifier input sensitivity adjustment. Also check your subwoofer pre-out level at the head unit if you have this connection.

[Bishop]

thanks a lot, also the head unit i have is this one
http://www.jvc.ca/en/consumer/product-detail.asp?model=KD-SX980
if it helps any.

ill try that out tomorrow, any other suggestions while im out there?

[Ziggo]

It seems to me that you are running your amp in 4-channel mode. From JL's site, your subs' RMS is 125W. If you want your amp put out 2x100W RMS (according to the Alpine site), you have to run it in "bridged" 4-ohm mode. This is what I've done in my setup. Usually, this means hooking up one sub to the + Front Left and - Rear Left, the other to the - Front Right and + Rear Right. Check your manual to make sure.

The way you have it hooked up now, you're only putting out 40W RMS to each sub. That is the reason why your bass sounds weak.

Goodluck!

[Lukydogg]

As far as I can tell, you are only using 2 ch off the amp, right? Bridge the 1/2 together for 1 sub, then the 3/4 together for the other sub, check the gain levels on amp, and also what is the size of your sub boxes? The most common problem is not enough air space, or actually too much, but too much makes more boom, then a smaller box is tighter punch. Are the boxes the same size?

[Bishop]

thanks for the quick relpys!

Yeah i only want 2 channels off of the 4 channel amp.

ill try differnt ways of bridging to see which gives off the best bass.

i made the boxes myself and they should be very close to being the same size. From my calculations they should have 1.5 cubic feet. maybe + or - a .1-.2 but that shouldnt matter to much right?

Also what should the gain levels on the amp be at?

thanks again everyone!
bishop

[EWF]

Even if you were only putting 40 watts RMS into your subs, you shouldn't be getting, "didnt seem to make very much bass and made very little difference." Even with modest power, you should at least hear a discernible difference if your subs are connected and working properly. Of course, we don't know what YOUR definition of "very little difference" is, but I'm assuming that you mean they don't sound like they are doing much - almost like they're not even there.

[dv6cougar]

hey to help you out with your box... if you have .1 less airspace for a sub then recommended your gonna loose some bass at low volumes, no major difference at all, but some but once you crank it up you there is no difference in bass from either sub
at least from what my buddy told me, he did that with his 3 jl audio w 6's, one sub had .1 less air space then the other 2 and you could literally see it bounce different from the others but once he cranked it they all fired together.
Hope that helps mike

[Bishop]

thanks a lot guys, i finally got them working, had to rearange the wiring several times. What i found worked putting them together then bridgeing them off of 1 and 2. Would putting them together like that cause any loss of power?

also, im getting some light static/thumping from the subs when i am just turning the car on/off and in between songs. Any idea to what could be causing that?

thanks again
bishop