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Discussion Starter #1
Hey all!

I wanna start my subwoofer and amp project soon and was wondering if I could get some help from the resident audio gurus out there.

I want to put this sub into my car above the spare tire:

http://www.pioneerelectronics.com/p...B,00.html?compName=PNA_ProductDetailComponent

It's a shallow mount (4" mounting depth) 12 inch subwoofer rated at 4Ohms, 1200W max, 300W nominal.

Anyways I'm not very good with all this Ohm-age and watt-age stuff. If someone could explain to me how I would choose an amp for this sub that would be compatible with the stock head unit it would be great!

Is nominal Wattage the same as RMS wattage? I was looking at this amp:

http://www.crutchfield.com/S-grgx4G...=0&cc=01&g=130&id=essential_info&i=500MRDM300

It's a pretty small unit and I was planning on putting it under the passenger seat or somewhere hidden.

Anyways my goal is to place a sub much like Shajan did so that I can keep my spare tire. I like to keep my cargo space. I also want something with more kick and I think this 12" will do it. It's a brand new sub that has just been released (shops don't even have them in stock yet) but once they do I plan on getting it. I'll be doing most of the install myself minus a few things (cutting out the circle in my floor board, etc.)

Thanks in advance. Looking forward to reading all your replies!

Andrew
 

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Hi Andrew, that sub looks impressive.

I'm by no means an audio expert but just a hobbyist but here are my suggestions.

Yes, 300 is the RMS or continuous wattage it can handle. I'd probably get an amp pushing atleast 200 WRMS for that sub though 150W may be enough. More is better to counter distortion.

One question, how do you plan on holding the sub and the spare down? That was the main reason I went with 2 6.5" 'coz that way I can use the factory screw to hold down the spare and the sub.

Good luck and keep us posted.
 

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Discussion Starter #4
[quote = shajan]One question, how do you plan on holding the sub and the spare down? That was the main reason I went with 2 6.5" 'coz that way I can use the factory screw to hold down the spare and the sub. [/quote]


Shajan,
The current set up has it that the spare is held down by the long screw which also hold the Bose sub. I think it's possible to get a rod with the same threading as the current screw. Then just get a shorter rod and screw it underneath the new sub box.

By the way, have you completed your subs? How is the kick with the 2 6.5's?

This probably isn't practical due to our locations, but I'll offer anyway: I have a boat-load of woodworking tools and can fabricate just about anything (even cut a circle for ya). Let me know.
ParticleFX - very kind of you to offer your help. I will keep this in mind when I come to building everything.

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About the amp, I'll look around for one that's 200W RMS. I don't want to buy an overly expensive sub.

Oh I found a guy selling a JL Audio 250.1 Mono amp rated at 250W @1.5-4ohm for $225-ish:
http://www.jlaudio.com/amps/2501.html

Is this a good amp for the sub?

Thanks guys.
 

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You want an amp that will at least push 70% of the the RMS rating on the sub. Its always better to have a more powerful amp than to underpower your sub because you can always adjust the amps output.
Remember to look at the amps RMS rating. Peak power numbers aren't gonna help you any. And The next crucial step would be to make the right enclosure. Try to stay within the specified range of enclosure volume that the subwoofer manufacturer recommends for the best results.
Getting the Blose system to work with an aftermarket amp is the next challenge. One that some have tackled and one whicch I am worried about. I will be installing my sub and amp as soon as my Monster Cap comes in. Hope this helps.

BTW, that JL amp would be great for the sub you are looking at. JL amps are a bit pricey. Try looking into Memphis/PPI/AMPLE. These are great amps.
 

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Andrew, where are you getting that sub from?

That JL Amp is more than adequate for your needs. It's got good THD and RMS ratings.
 

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Discussion Starter #7
Thanks a lot for the responses. I think I may just go with the JL Audio amp. Someone on the 350z forum is selling it for a good price.

As for the sub, I emailed a couple places closeby Boston (Long Island, Brooklyn, etc) that I found online. They don't have them in stock yet but they will be stocking them and I'll be notified by email when they come in. No idea what the price they'll be selling at is but it definitely will be less than the $220 msrp (my guess about $199.99?)

I'm also worried about gettin the amp to work with the Bose system. How have people gone about doing this?

Thanks all!
 

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Since the Bose is either 1 or 2 ohm (really screwed up), I think people have been splicing the rear speaker outputs from the headunit (pre-amp) and using a line converter. Not 100% about this... but pretty sure how it's been done.

Anyone that have done subs care to chime in?
 

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Yup...you need to use a LOC line out converter. A good one that the Acura with Bose peeps have been using is the Soundgate Locprea. You tap inot the signal wire for the sub before the Blose amp. This is the best methos I have read about so far. Another way is to tao into the wires behind the head unit and use diff. LOC but since we have a stock sub no need for that.
A third way is to do what Ujmot recommended but people have complained about a lot of white noise and crappy sound quality.
 

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Andrew, those 6.5 JL's really surprised me. They pack quite a punch. They really sound great without the trunk covers. They are in the stock Bose sub location and I didn't make a cutout in the trunk cover(floor) and I also have the rubber mat on top. This is causing a lot of extra noise when the volume is up. I'm still deciding on cutting a hole in the floor for the woofs to breathe.

I'm using a Xtant 3 channel amp which has balanced inputs so I didn't need a hi-lo converter. It works great and there's no noise at all. It is currently driving my Bose front (l & R) speakers also. Eventually replacing them with better components.

PS: Particlefx, wish you lived in the Long Island are :) I'm into making speakers etc.
 

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Discussion Starter #11
Is the Soundgate LOCPREA unit just to change a pre-amp signal to a speaker level signal? The JL 250/1 amp allows for both signals to be used. I'm quite confused on what the Soundgate device actually does. Care to explain a bit more?

I was thinking that I would just tap the subwoofer line before the amp in the subwoofer and plugging that into the new JL amp. Will this not work?

The JL Amp has this spec:

Input Range:
switchable from 200mV-2V RMS
to 800mV-8V RMS

In the PDF file it also says it accepts preamp level and line level inputs. Does this mean I can skip the Soundgate LOCPREA? Or is the LOCPREA only so I can have RCA connection from my speaker wires?

The PDF file for the connectors can be seen here:

http://www.jlaudio.com/amps/pdfs/250_1.pdf

Will I need to get a hi-lo converter? The JL 250/1 has a amp low-pass filter. This functions as a hi-lo converter right?

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Shajan,

I plan on cutting out a circle in my cargo area floorboard. Then I'm gonna take some plexiglass and cut that into a circle and cover the sub and make the plexiglass flush with the cargo floorboard. I'm planning on putting my amp somewhere else, maybe under the passenger seat if possible.

I don't have the rubber cargo tray. I plan on getting the carpeted cargo mat from my dealer or maybe from Grubbs sometime.

I have a feeling making it all look nice is going to be easier than understanding how to get all the wiring done. lol.

Anyways this is a learning experience for me. I used to have all my audio work done professionally but this time I want to tackle it myself! Think this will be fun. Now if only that sub were released already... That's all I'm waiting on right now. :)

:D
[/url]
 

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Is the Soundgate LOCPREA unit just to change a pre-amp signal to a speaker level signal
Bingo. The good thing about this one is that you can control the output on the LOC. SOundgate also has a LOCb or something liek that but it emits too much signal and people have complained about he noise. The website recommends the LOCb but peopl ehave been saying tha the LOCprea is the one to use.

This will explain it alot better.
http://www.soundgate.com/products/line-output/index.htm
http://www.soundgate.com/products/line- ... type-2.htm

You would want to use the TYPE2 installation because our blose system believe it or not are amplified.
 

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Andrew,

Yes, you will need a LOC because Bose sends balanced inputs to its amps. I think I measured mine to be about 8 volts. LOC converts balanced inputs to line levels that can go into your amps RCA inputs. Once you get that, it should be fairly easy. You can get your remote start line and the balanced inputs from the connection that goes into the factory sub.
 
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