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Tom_15
Joined: 19 Nov 2006
Posts: 47
Location: Armstrong B.C., Canada
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 Posted: Sun Feb 17, 2008 6:08 am Post subject: Ground location for Amp |
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I'm finally getting around to installing my stereo system and I can't seem to find any decent spots in the hatch to ground my amplifier to. I only have about 2 feet of thick wire at the moment so the ground spot would need to be in the hatch area.
Has anyone found a decent spot to ground their amp in the rear hatch?
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924RACR
Joined: 29 Jul 2001
Posts: 9107
Location: Royal Oak, MI, USA
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| Posted: Sun Feb 17, 2008 6:20 am Post subject: |
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I think I grounded mine at one of the gain ground points between the taillights, same as the fuel pump, taillights, etc.
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Vaughan Scott
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2Fast
Joined: 09 Dec 2007
Posts: 459
Location: Klamath Falls, OR
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| Posted: Sun Feb 17, 2008 10:09 am Post subject: Re: Ground location for Amp |
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| Tom_15 wrote: | I'm finally getting around to installing my stereo system and I can't seem to find any decent spots in the hatch to ground my amplifier to. I only have about 2 feet of thick wire at the moment so the ground spot would need to be in the hatch area.
Has anyone found a decent spot to ground their amp in the rear hatch? |
You could probably run the wire down, into the area where the sunroof drain ends up. Then go through the rubber seal & screw it into the frame. I would do what 924RACR did/said and ground it to the ground between the two tail lights. Both would probably work though  .
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=====>Alex<=====
1979 Porsche 924 NA 5spd
1979 Parts Porshce 924 NA 5spd |
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Tom_15
Joined: 19 Nov 2006
Posts: 47
Location: Armstrong B.C., Canada
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| Posted: Sun Feb 17, 2008 3:13 pm Post subject: |
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I ended up going to the back of the tail lights and it worked great. The beloved BOOM BOOM has arrived.
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1978 924 N/A 4-Sp. |
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tuurbo
Joined: 08 Aug 2007
Posts: 1446
Location: East Windsor, New Jersey
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| Posted: Sun Feb 17, 2008 3:17 pm Post subject: |
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| There are two spots near the spare tire well - one of them is already used as a ground for the lights. |
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924RACR
Joined: 29 Jul 2001
Posts: 9107
Location: Royal Oak, MI, USA
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| Posted: Sun Feb 17, 2008 11:28 pm Post subject: |
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Aw yeah!!! 
Did you stick the box itself in the spare tire well, as I did?
I'm still enjoying the boom, if perhaps a little less than I did when I was younger! (god I feel old!) But now I have to overhaul much of the rest of the system... need a new headunit, since I seem to have burned out the amps in mine, and so also need to install an amp for the main speakers - evidently it does take quite a bit of power to overcome the road noise in our old cars at speed!
Here's a question; I have 6.5"s in the back, 4x6's up front in the doors. I'm wondering if I should try to get by with only a 2-channel unit to drive the rears, or if I'm just fooling myself and need a proper 4 channel?
Opinions?
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Vaughan Scott
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Smoothie
Joined: 01 Jan 2003
Posts: 8032
Location: DE (the one near MD, PA, NJ)
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| Posted: Mon Feb 18, 2008 12:31 am Post subject: |
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| 924RACR wrote: | Here's a question; I have 6.5"s in the back, 4x6's up front in the doors. I'm wondering if I should try to get by with only a 2-channel unit to drive the rears, or if I'm just fooling myself and need a proper 4 channel?
Opinions? |
Are you talking a seperate 2-channel amp driving the rears alone? If yes, that's fine (as long as you're not overdrawing the amp as explained below).
If you're thinking of driving 2 fronts + 2 rears with a single 2-channel amp - it will depend on the power and impedance ratings of the amp, and how the speakers are wired (either series or parallel). Some amps are ok with a load of 2ohms per channel, some say 4ohms, others may be 8ohms.
Wiring in series increases impedance - wire two 8 ohm speakers in series and you get a load of 16ohms on the channel they're on (this results in less volume, but is safe for the amp). Wire the same 8ohm speakers in parallel and their combined load goes the opposite way, to 4ohms (this results in higher volume, but would blow an 8ohm amp, so you'd need either a 2 or 4ohm amp).
Likewise, two 4ohm speakers wired in parallel become 2ohms, so you'd need a 2ohm amp. A 4 or 8 ohm amp would be damaged by a load of 2ohms.
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924RACR
Joined: 29 Jul 2001
Posts: 9107
Location: Royal Oak, MI, USA
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| Posted: Mon Feb 18, 2008 1:25 am Post subject: |
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Actually, I was wondering if I'd be OK sound-wise with only driving the rears with a 2-channel amp, or if I'd still want the fronts also driven by an amp (in which case yes, I would do a 4-channel amp).
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Vaughan Scott
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Rasta Monsta
Joined: 12 Jul 2006
Posts: 11733
Location: PacNW
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| Posted: Mon Feb 18, 2008 3:02 am Post subject: |
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I think it makes sense to run the fronts from the internal power of the head unit and the rears from an amp.
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- WeiBe (1987 924S 2.5t) - 931 S3
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Smoothie
Joined: 01 Jan 2003
Posts: 8032
Location: DE (the one near MD, PA, NJ)
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| Posted: Mon Feb 18, 2008 3:23 am Post subject: |
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I have the front-center dash and the two on either side of the rear seats driven by the front speaker outs of the receiver (head unit). Then I have a rear amp attached to the head unit via its' line-outs (and the amps' line-ins). The separate amp drives 2 woofers in the hatch area. -And the head units' front-rear fader controls the relative volume front-to-rear.
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"..it's made in Germany. You know the Germans always make good stuff."
'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox |
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924RACR
Joined: 29 Jul 2001
Posts: 9107
Location: Royal Oak, MI, USA
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| Posted: Mon Feb 18, 2008 4:31 am Post subject: |
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OK, yeah - I was kinda doubting the little 4x6s would really need all that much power, they're really not much more than filler, it's the rear speakers (in the rear seat area - under the rear quarter windows) that really provides most of what the system has to offer.
K THX BYE!
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Vaughan Scott
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Tom_15
Joined: 19 Nov 2006
Posts: 47
Location: Armstrong B.C., Canada
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| Posted: Mon Feb 18, 2008 5:50 am Post subject: |
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| 924RACR wrote: | | Did you stick the box itself in the spare tire well, as I did? |
I only wish that I could have got it in the spare tire well but I have a massive BASSWORKS ported box that takes up half of the hatch.
I guess it's time to pop out the rear quarter windows for the rear speakers. Goodie
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Rasta Monsta
Joined: 12 Jul 2006
Posts: 11733
Location: PacNW
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| Posted: Mon Feb 18, 2008 6:20 am Post subject: |
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Or you could do that Red's PO did. . .pull the inside trim loose from the window gasket and leave it that way.
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Toofah King Bad
- WeiBe (1987 924S 2.5t) - 931 S3
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