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Old 10th March 2012, 08:41 PM   #1
diyAudio Member
Join Date: Jan 2012
Default Very Open Thread. Curious To See Responses

I will be keeping my vehicle for another 6 months & will be upgrading the Audio System so I can have a more enjoyable ride in the mean-time.

Vehicle: 05' Legacy GT

OEM Sound System Lay-Out: 6.5" all around (depth: 3"). Components up front, coaxials in the rear. Amplified Sub(woofer) underneath driver seat.

Additional: Tweets are located near door handles near side mirrors. Tweets are slightly angled towards the rear of the vehicle. Sorry for my lack of knowledge, but wouldn't they be considered "on axis" because they are angled less than 180 degrees? They are around 170 degrees.

Budget: $150-175

I plan on retaining my rear speakers & selling both my fronts & amplified subwoofer. W/ the items sold, I should be able to get around $150. I will be retaining my OEM HU which puts out roughly 20 RMS per channel. There is also a seperate channel that sends a signal to the OEM amplified subwoofer. -I assume this is "high level" because there are no RCA's.

Here's what I am thinking: Swap out the fronts. -I would like to experiment W/ raw drivers from most likely parts express. However, I only have 2 channels, thus I would need some type of passive crossovers. How hard are these to fab? I could buy passive crossovers, or even a passive component set, but I would really like to learn & head the hard way lol. As far as a subwoofer, there is a 7-8" pre-cut hole in the rear deck. I am thinking about heading IB.

With the budget I have, I may end up buying "used" & I do not mind at all. I should be able to obtain a set of tweets, mids, & a cheap subwoofer W/ amp for $150 than probably spend $25 or so on additional wiring, sound dampener, CDT tiles, etc.

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Old 15th March 2012, 03:05 PM   #2
diyAudio Member
Join Date: Aug 2011
Simple passives aren't hard to make, PE actually has a forum for info on them.

Woofers look for ones that play high 5k is good, means you can have your tweeter crossed 4K and up.

IB sub, the hole may be 7-8" but a 7-8" IB sub will be a waste of time, go as big as your shelf will accept (underneath, don't worry that the hole is smaller)

Deaden the hell out of your doors, other areas aren't as important-though the top vanity shelf will likely rattle it's tits off with any sub under it.

Honestly I'd say to up your budget, get a decent 4 ch to run the fronts and the sub.
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Old 16th March 2012, 05:21 AM   #3
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Join Date: Jan 2012
^Thank you for the response! I will be doing some research on passive x-overs.

On the woofer. I can either go above or below the deck. -Above seems like a better idea & I will explain soon. I'm sure I can fit a baffle & suit a 10" depending upon the basket.

Going below the deck would allow me the option of heading W/ a larger subwoofer (more cone area=yes), but wouldn't diffraction play a role? -or does diffraciton only play a role W/ frequencies ohh idk extending from 2k and up?
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Old 16th March 2012, 04:43 PM   #4
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Join Date: Aug 2011
No worries.

Above may be, I have a customer who fitted a Pioneer shallow 8" under the shelf and it rattled the hell out of the shelf-what ever you do the shelf defo needs some serious attention.

I've never tried it myself, but I hang out on diyma and the advice is regularly given to go as big as you can and not to worry about the hole being smaller, I shouldn't think that it would cause any diffraction issue-wavelengths too long.
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Old 16th March 2012, 05:25 PM   #5
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Ah, yeah I've been on diyma a few times. -That forum went to shiit after Ant sold it.

I am thinking about a Dayton HO
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Old 17th March 2012, 12:17 AM   #6
jol50 is offline jol50  United States
diyAudio Member
Join Date: Nov 2007
You want an IB sub, that would be a low Fs and high qts like .7. A 15 can have Fs 20Hz but a 12 usually can't get that low and still have high qts (usually 25-35 for a 12). That will give you a fairly flat FR from the Fs on up, you will not have to EQ it much. Larger cone area equals more efficiency, it will go louder the more you have on same least up to quads it will.

I used a pair of pyle 15s IB they work well, Fs 20 qts .7. They are pretty flat from under 30 on up. I have another car I want to hang one of them in the rear deck. You need about half the cone area for your hole typically, it depends on how much xmax you push. I'm glad they did work well as I had no idea, some cheaper subs have cone noises and so on. But I tried because a pair of 15s was overkill I didn't really need that much....but wanted the cone area and low fs to reach lower. It can hit 25hz well enough to use, below that is hard to gauge how strong it is. There are not that many subs with good IB specs, you will have to EQ other subs more. You need to consider this if you can't tune with EQ.

You could pick up a used 4x50rms cheap enough. 'On axis' is the tweet aimed right at your ear. You can use foam under the rear deck cover to help with rattles.
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Old 17th March 2012, 04:10 AM   #7
diyAudio Member
Join Date: Jan 2012
Yes, -I have been lurkin' around diyma for the past year or so. I can follow you, but there are some things about car audio that I do not know.

I see a few drivers that suit my application w/ high-er Fs values. -Does this really matter? I mean, it'd just require a bit more tuning, correct? However, I will be using my OEM HU, so ha not much room for EQ'ing lol. -There is a thread on the LegacyGT forum on how to modify the OEM Hu for an un-EQ'd line out...

I still would need some type of processor. This may take some more research, but there is a Mini DSP on the classifields right now for very cheap. I also found a cheap oldschool A/D/S amplifier I may get, which would leave a bit of room for the DSP. It's just a 2 x 4 board.

Question: My OEM HU has 4 channels & a 5th channel for the OEM Amplified subwoofer. Would the channel going to the OEM Amplified subwoofer be "high level." There are no RCA's, so I am pretty confident they are, but being OEM, never know I guess. I know the Pins so couldn't I run an amplifier (that accepts high level inputs) off the subwoofer channel? -This would be weird as the wires are like 14 gauge lol if that.

Ha, while I have the OEM amplifier on hand, I should grab the schematics & start etching my own lol.

Gotchya. Yea I was jus checking being that it was only litterely a few degrees less than 180. ...I'd call that pretty close to "on axis" but techincally its considered "off"
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Old 17th March 2012, 03:00 PM   #8
diyAudio Member
Join Date: Aug 2011
jol50=sqshoestring? Nice to see you on here too.

The lower the FS the better, IB is effectively* running the sub in Free Air, Fs is "Free Air Resonance"-so the lower the better, below it performance drops off. Adding EQ below Fs will introduce more distortion and be harder to impliment than buying the correct tool for the job in the 1st place.

*obviously in a car the boot acts as an enclosure, if it's volume is more than 3x VAS it can be considered IB/Free Air (at leat that's what I understand, I've never had a saloon to try myself!)

To check your sub out on your stereo get a multimeter across it-more than likely a line level rather than speaker/high level, just because there's no RCA doesn't mean it's speaker level, car makers use proprietary wiring for everything so wouldn't use an RCA at build level (some do for accessories like AV systems, but that's rare and normally when they've cut a deal with an aftermarket manufacturer after the vehicle has passsed initial design stages)

A/D/S amp should be a good contender, sold a few in the past (big 8ch slabs) and they "sounded" great
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