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-   -   Picking the Right Amplifier (http://www.wranglerforum.com/f40/picking-the-right-amplifier-235542.html)

Jaybirdd 04-15-2013 08:02 PM

Picking the Right Amplifier
 
I just replaced my headunit and speakers but am getting some distortion at the high volumes I need for doors off highway driving.:banghead: From what I've read, I just need more power (specifically an amp). My current setup is:

H/U- JVC KD-R330 (20 W RMS x 4)
Dash- Kicker 5 1/4 in. DS525 (6-35 W RMS)
Soundbar- Kicker 6 3/4 in. DS65 (6-50 W RMS)

I plan to polyfill the area behind the speakers but I want to do this the right way and not blow my new speakers. Right now I'm looking at the Alpine KTP-445U Power Pack and the Alpine MRP-F300. Would either of these work for my situation or can you recommend any other amps for $150 or less?

woansleftpeg 04-15-2013 08:30 PM

Alpine make good amps and you've made a couple of decent choices there, I think. You can spend considerably less if you wish, though; you can buy a perfectly serviceable four channel amp giving you 4x50W RMS for less than fifty bucks. It may not have quite the level of quality that the Alpine units do, but you may very reasonably decide that for the sake of $70-80 it's best to do the job well and do it once.

overblown 04-15-2013 08:32 PM

You definitely need more power. That headunit is begging for mercy. Go with the F300 and be merry.

Jaybirdd 04-15-2013 09:33 PM

I read on another thread that it would be possible to use a 2 channel amp and possibly save some money that way by wiring the front speakers in one channel and the soundbar speakers in the other. Is this a good idea? Also how important are the adjustments on the amp itself? The power pack has no knobs or switches on it which might be better for me considering I dont know much about gain etc.

woansleftpeg 04-15-2013 09:40 PM

You can theoretically wire the speakers in series, but no-one would do that. If you want to save money on the amp, buy a less expensive one than the Alpine. There are perfectly decent four channel Boss Audio units on Amazon for $45.

You don't need to worry about a lot of settings on the amp, once it's installed you won't touch it anyway.

overblown 04-16-2013 01:25 AM

True. You aren't in need of a ton of power or high end features. I've used Boss Audio amps before with great results.

mcdull 04-16-2013 03:19 AM

Anyone know if I can use JK's stock subwoofer with aftermarket amp?

woansleftpeg 04-16-2013 04:38 AM

Quote:

Originally Posted by mcdull (Post 3642715)
Anyone know if I can use JK's stock subwoofer with aftermarket amp?

No reason why you can't, but it's a POS.

Jaybirdd 04-16-2013 08:56 PM

Thanks for your help guys. Ive decided to go with the BOSS CE404 (50W x 4). I found it on Amazon for only $43 and it should power my new speakers just fine. One last question, will I get away with just buying the BOSS Kit-2 8 gauge installation kit? Amazon.com: Boss KIT-2 Complete 8 Gauge Amplifier Installation Kit: Car Electronics Will I need anything else?

woansleftpeg 04-16-2013 11:29 PM

Personally I've always used 4-gauge wire for powering an amp, but the specs for yours say 8-gauge is good so you should be fine with that kit. Just make sure that your ground is at least the same gauge as your hot cable, and that you follow the basic rules for installing an amp around the order of installation for each cable.

BlueRidgeYJ 04-17-2013 06:26 AM

400W/12V=33A, 8ga can carry up to 50A. You are fine with that kit. :)

Jaybirdd 04-17-2013 03:09 PM

Thank you everyone! Ill post some pics of my completed setup when I'm done.

woansleftpeg 04-21-2013 03:37 PM

Quote:

Originally Posted by BlueRidgeYJ (Post 3647075)
400W/12V=33A, 8ga can carry up to 50A. You are fine with that kit. :)

Just revisiting this as I'm doing my amp currently, and it had stuck in my mind. Your math is technically correct, but real world not so much because you're assuming 100% efficiency of the amp. You should assume that an amp is going to run at around 50% efficiency with the rest being turned into heat, so in fact to get the full 400W from the amp you're going to require more like 66A, which is going to be pushing things on 8ga cable. Even 6ga is only rated to around 60A, I think.

Obviously as long as OP isn't driving around everywhere with the system at full chat all the time then it's not going to be an issue, and running the amplifier at half of its rated RMS is going to have him well inside safe parameters for the power draw over 8ga cable. Just worth bearing in mind though - there's no actual downside to overspecifying the cable, so for the small extra cost it's worth putting in a heavier gauge cable than you're likely to actually need.

BlueRidgeYJ 04-21-2013 07:53 PM

Yes, there does need to be a margin of error but the difference in 33A and 50A is a 33% margin.... more than enough for an amp that will be set up 4x50 @ 4 ohms, not 4x100 @ 2 ohms, based on the OPs speaker choice. Using 12V also builds in an additional margin as alternators put out 13-15 vdc, usually ~13.8, which would be about 29A @ 400W, assuming full efficiency.

OP, with 8 ga you will be fine. If you want larger wires for future expansion, feel free.

=)

Jaybirdd 04-22-2013 04:32 PM

Glad to see these arguments on my behalf. I went with the 8 ga kit and after moderate testing everything sounds awesome. Now I just need to fab some kind of mount for the amp beneath my steering wheel. Its currently duct taped to the firewall ;). No extreme heat at full volume and I dont plan on adding anything else to the current system so I should be okay. Thanks again for your help guys!

woansleftpeg 04-22-2013 05:44 PM

You shouldn't need to fabricate anything, the stock amp goes under the steering wheel. I don't know if the mounting plate is there by default, when you remove the driver's side speaker pod is there a metal plate behind it? If not you should be able to buy one from your dealer, or if you prefer I can measure mine (I removed it, so it's easily to hand) and give you the dimensions and screw locations.

BlueRidgeYJ 04-22-2013 06:01 PM

Quote:

Originally Posted by Jaybirdd (Post 3669193)
Glad to see these arguments on my behalf...

No arguement - he isn't wrong. With your particular setup, 8ga will suffice, but were it a more boom-boom setup you would need to step up a bit. I should have been more thorough in my original response.

Glad ya got it all worked out.

Cheers

Jaybirdd 04-22-2013 07:45 PM

From what I've read from other threads, I assumed I would need to make one of these http://www.jeepz.com/forum/attachmen...rangler-tj.jpg or possibly buy one. I didn't notice any metal plate behind the left speaker when I replaced it but I'll make sure to check it out when I get a chance.

woansleftpeg 04-22-2013 10:05 PM

Quote:

Originally Posted by BlueRidgeYJ (Post 3669485)
No arguement - he isn't wrong. With your particular setup, 8ga will suffice, but were it a more boom-boom setup you would need to step up a bit. I should have been more thorough in my original response.

Glad ya got it all worked out.

Cheers

Yeah, you're right - the impedance of the speakers means that he's not going to overload the power cable. Or at least, he's going to blow the speakers before anything catches fire!

woansleftpeg 04-22-2013 10:17 PM

Quote:

Originally Posted by Jaybirdd (Post 3669902)
From what I've read from other threads, I assumed I would need to make one of these http://www.jeepz.com/forum/attachmen...rangler-tj.jpg or possibly buy one. I didn't notice any metal plate behind the left speaker when I replaced it but I'll make sure to check it out when I get a chance.

That's not quite what mine looks like. The black unit is obviously the amp (I didn't get round to taking it off the plate yet) and ignore the duct tape, it's keeping the mounting screws with the plate:

http://i.imgur.com/W5y65qQ.jpg

http://i.imgur.com/tmfIHPs.jpg

Jaybirdd 04-22-2013 11:42 PM

I didn't have a stock subwoofer or a center console for that matter, so unfortunately I don't think I got the stock amp/bracket either. The space should still be there so Ill look into mounting mine where your stock one was possibly with a stock bracket. Other people mounted it to the steering column like this Skinny Pedal Jeep TJ Amp Bracket

woansleftpeg 04-23-2013 10:28 AM

Ah. I should have asked which Jeep you have; I don't know the mounting points in a TJ.

Jaybirdd 04-23-2013 07:38 PM

Quote:

Originally Posted by woansleftpeg (Post 3672484)
Ah. I should have asked which Jeep you have; I don't know the mounting points in a TJ.

Thanks anyway. I'm sure I'll figure something out. At least it sounds great now.

Jaybirdd 06-04-2013 12:48 PM

My system was working flawlessly for months but recently the head unit started to show a miswiring warning. I reset the hu and it worked for a few days but now the warning wont go away. I checked the connections at each speaker and they are all solid. I did notice that the amp's power indicator wont turn on. I checked the remote wire that goes from the hu to the amp and it seems fine. Any idea what the problem could be?

CoreyZ 06-04-2013 01:32 PM

Id say that temporarily, move the amp turn on wire to a different switched source. Get it off the wire harness and off the head unit. See if that fixes your problem.

Jaybirdd 06-04-2013 06:47 PM

Could I just run a small wire from the amp power cable to the remote port? Or would there be too much wattage direct from the battery for the remote turn on port to handle?

BlueRidgeYJ 06-04-2013 07:09 PM

Quote:

Originally Posted by Jaybirdd (Post 3825744)
Could I just run a small wire from the amp power cable to the remote port? Or would there be too much wattage direct from the battery for the remote turn on port to handle?

Yes, temporarily. It will be on anytime the amp line has power, though (typically 100% of the time). The load determines the draw of current, not the supply or wiring (as long as you have common voltage).

Jaybirdd 06-05-2013 07:37 PM

After a simple test, I have found out that my amp is still working fine. The head unit is discovering some kind of problem as soon as I turn it on and is cutting the power to the remote turn on wire which is the reason the amp wasn't turning on. I've checked the wires coming out of the HU and they are all perfect. (I used wiring harnesses instead of splicing just to make sure) What should I check next?

Mattk11 06-06-2013 07:48 AM

Quote:

Originally Posted by Jaybirdd (Post 3829640)
After a simple test, I have found out that my amp is still working fine. The head unit is discovering some kind of problem as soon as I turn it on and is cutting the power to the remote turn on wire which is the reason the amp wasn't turning on. I've checked the wires coming out of the HU and they are all perfect. (I used wiring harnesses instead of splicing just to make sure) What should I check next?

Do you have anything else connected to you amp turn-on wire? Sometimes if you have a relay or a parking brake bypass it can overload the CanBus and shut off the factory POS amp.

Jaybirdd 06-06-2013 12:45 PM

Quote:

Originally Posted by Mattk11 (Post 3831329)
Do you have anything else connected to you amp turn-on wire? Sometimes if you have a relay or a parking brake bypass it can overload the CanBus and shut off the factory POS amp.

Nothing else is connected to the amp turn-on wire and I have a tj se so there was no stock amp. The harness that I got from Radioshack didn't have a turn-on wire coming out of it to connect to the amp so I shoved one into the plastic clip thing myself. I know I had it in the correct spot because everything used to work just fine. Maybe it just came loose? Would an unattached turn-on wire make the HU mad? I'll try to solder that connection really well and see if that fixes my problem.


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