Would adding fans help?

[GlassWolf 5]

Have you done any testing to support your claim that grounding to the frame in a modern vehicle is equivalent to 4AWG?

I haven't done any personally, no. That testing was done with welding research for automobiles, but electricity is electricity, and it applies to this situation as well. I apologize for not having anything from the internet to provide a link. That data as acquired before the internet was quite so prevalent. I'll see what I can find on-line when I have the time, though.

Anecdotally, if you observe the higher levels of SPL competitors however, you'll note that very rarely will you ever see anyone using a chassis ground for their amplifiers, instead choosing to ground directly to battery bus bars most of the time. I guess that's one of the problems of being older than the Internet.. haha Not everything I learned came from a computer. lol

While I don't consider this valid "research" I can say that higher SPL numbers in controlled environments have been attained by using direct to battery grounding vs chassic ground in high current applications with SPL competition vehicles by myself and others, too. The same goes for using multiple ground runs vs single runs. SPL is a bit of a goofy thing.

Edited May 26, 2010 by GlassWolf

[Sir-Lancelot 216]

@ GlassWolf

Where in SC are you?

I am in Florence.

[Duran 387]

It's hard to sift through all the SPL rules of thumb and separate the facts form the BS, because there is a lot of both. The only way to find out what works for a specific vehicle is to test it yourself it seems, in most cases. It seems like you have quite a bit of knowledge on the subject, I encourage you to share.

[GlassWolf 5]

It's hard to sift through all the SPL rules of thumb and separate the facts form the BS, because there is a lot of both. The only way to find out what works for a specific vehicle is to test it yourself it seems, in most cases. It seems like you have quite a bit of knowledge on the subject, I encourage you to share.

the bit on the welding was information I'd garnered from welding data on automotive work from restoring old cars, really, but it applied to this in part. The data was in regards to resistive spot welding of sheet metal (joining subframe to floor pans and such.)

I've been looking around the net, but most of what I find isn't on specific measures of electrical resistance. The data I'm finding is more to do with tensile strengths of welds, and the electrical resistance changes of welds from liquid to solid during the weld process.

I'm outside of Columbia, in Lexington. Just moved here last Fall.

Edited May 26, 2010 by GlassWolf

[b34tBoX 0]

Thanks for the help so far guys.

I've relocated ground to seatbelt bolt (sanded prior) that goes right into frame. So far no issues with the 600 cutting out, but I have been cruising around with A/C on fairly high. Have not noticed much of a temperature decrease when I touch the amps.

One issue I've noticed before and after relocating ground.

After extended periods of music the subwoofer likes to fade out and become fairly inaudible. No protection light on amp, just goes REALLY faint. Nearly off.

I had the input selection to 2V-8V assuming my Alpine 9885 is a 4V out.

When I switch to .1V-2V it becomes functional again, so have left it like that.

I tested the RCA's with a DMM set to 200, and they all read .02V at the amps, now does that mean 2V or 200x0.02 = 4V?

I've included pictures of amplifiers if you guys could review them, and give me feedback.

Set gains with volume @ 25/35 and subwoofer output @ 13/15.

HPF is set at 80Hz from HU.

2.250: http://sites.google.com/site/b34tbox/250.jpg

2.600: http://sites.google.com/site/b34tbox/600.jpg

1.2500D: http://sites.google.com/site/b34tbox/2500.jpg

Input on both two channel amps is at about 4/10 and monoblock is 6/10.

No bass boost on any of them.

Subsonic ~20Hz. LPF at ~80Hz on 2500.

Edited May 27, 2010 by b34tBoX

[GlassWolf 5]

it's not abnormal for amplifiers to be hot to the touch. That's a side effect of producing that much power output.

A fair number of alpine head units are 2 volt pre-out models, although I don't know for sure on yours specifically without looking it up.

in regards to the amp fading out on you, it sounds like the amplifier may be damaged, but if it works @ the 2 volt setting, then yeah just leave it there as long as the amp is not clipping.

On using the seat bolt as a ground spot.. I usually advise against that. It's not a good place to use unless you're just really adamant about not putting a bolt into the floor pan or trunk floor of the car.

[Kanaworm$ 292]

On using the seat bolt as a ground spot.. I usually advise against that. It's not a good place to use unless you're just really adamant about not putting a bolt into the floor pan or trunk floor of the car.

Just curious as to why the seat belt bolt is not a good ground point?

[BanginGMC 23]

With what you are wanting to achieve I would recommend (4) fans.

(2) with the airflow moving inward from the left and (2) from the right moving the airflow outward.

Post 1,000 FTW! I'm blue now! :woot: :woot:

[GlassWolf 5]

Just curious as to why the seat belt bolt is not a good ground point?

safety issues since those bolts are there to hold the seat in place, and because if the seat does shift at all from having the ring terminal there, it can cause a faulty ground point.

It's a location that can get kicked if you have a back seat as well. Things like that. It's also possible to catch the ground wire with the seat rail when you slide the seat to position it, which can pull out the ground line from the terminal... blah blah.

[b34tBoX 0]

Hey guys, I think we've figured out the problem here.

After improving the ground location to the frame, and switching the input on the monoblock, things are sounding good, and no issues so far, even in this heat. (31*C / 87.8*F)

Yes, I'm using the seatbelt bolt, it only attaches to the belt and does not hold the seat in place. I also NEVER have any passengers in the rear, in fact my whole rear bench is out, ATM.

I could see if that location was used while people used the belt/seat that it would impose a safety concern..maybe. (As in probably not pass safety inspection, if they even noticed it)

Just wanted to say thanks for taking the time to help a newbie out!

(PS: I may drill a new location on the frame to even further improve the ground.)

Edited May 27, 2010 by b34tBoX

[GlassWolf 5]

Hey guys, I think we've figured out the problem here.

After improving the ground location to the frame, and switching the input on the monoblock, things are sounding good, and no issues so far, even in this heat. (31*C / 87.8*F)

Yes, I'm using the seatbelt bolt, it only attaches to the belt and does not hold the seat in place. I also NEVER have any passengers in the rear, in fact my whole rear bench is out, ATM.

I could see if that location was used while people used the belt/seat that it would impose a safety concern..maybe. (As in probably not pass safety inspection, if they even noticed it)

Just wanted to say thanks for taking the time to help a newbie out!

(PS: I may drill a new location on the frame to even further improve the ground.)

ah OK for some reason my brain was thinking "seat bolt" not belt bolt, but in any event, with the bench out, and using the rear seat belt bolt, yeah. Not really an issue if you've stripped the paint from that area to get a solid connection.