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-   -   Amp help (http://www.jeepgarage.org/f50/amp-help-5155.html)

mzh29 12-30-2009 07:22 PM

Amp help
 
Hey guys, I just bought a 400watt rms sub that's hooked up to a pioneer 5300t amp. I have it bridged to 380watts. I set the bass boost on the amp to 6 or half way up. Twice now after turning my jeep off briefly and then starting it back up I've got this constant "heart beat" coming from the sub. Like a sine wave, thump thump .... thump thump.... thump thump. I am guessing that it is probably the amp getting too hot, it did feel warm, but not smokin hot. Any ideas? I have the amp mounted inside the cargo tray area. Thanks!

Matt 12-30-2009 07:30 PM

Re: Amp help
 
Quote:

Originally Posted by mzh29 (Post 123437)
Hey guys, I just bought a 400watt rms sub that's hooked up to a pioneer 5300t amp. I have it bridged to 380watts. I set the bass boost on the amp to 6 or half way up. Twice now after turning my jeep off briefly and then starting it back up I've got this constant "heart beat" coming from the sub. Like a sine wave, thump thump .... thump thump.... thump thump. I am guessing that it is probably the amp getting too hot, it did feel warm, but not smokin hot. Any ideas? I have the amp mounted inside the cargo tray area. Thanks!

Where is the gain set?

Are you using a bass knob?

What kind of enclosure is the woofer in?

Is is a dual voice coil sub, or single? You're sure your sub is wired to 4 ohms, correct?


Non-pertaining advice: Turn the bass boost off. All that does is boost at a certain frequency (usually 40hz). It's not a volume knob or a gain knob.

mzh29 12-30-2009 07:54 PM

Re: Amp help
 
I had the gain set to "normal". It's in a ported enclosure 1.7ft^3. As for the wiring I just hooked positive to positive and negative to negative.

I still have the stock cd player, I know an aftermarket head unit would make it sound alot better.

Matt 12-30-2009 07:57 PM

Re: Amp help
 
Quote:

Originally Posted by mzh29 (Post 123444)
I had the gain set to "normal". It's in a ported enclosure 1.7ft^3. As for the wiring I just hooked positive to positive and negative to negative.

Define "normal" or give a percentage...?

What's the enclosure tuned to?

What sub woofer?

Is the woofer a dual voice coil sub, or single?

mzh29 12-30-2009 08:09 PM

Re: Amp help
 
It's a kfc-w3012 kenwood. I wanna say the gain is set to .4? On the kenwood website it says it has a "2 layer voice coil design", so I guess a single coil. The box is an hpr12g made by bassworx. I'm not sure what it's tuned to, can't find it anywhere.

Matt 12-30-2009 08:16 PM

Re: Amp help
 
Quote:

Originally Posted by mzh29 (Post 123452)
It's a kfc-w3012 kenwood. I wanna say the gain is set to .4? On the kenwood website it says it has a "2 layer voice coil design", so I guess a single coil. The box is an hpr12g made by bassworx. I'm not sure what it's tuned to, can't find it anywhere.

Ok, cool. It's a single 4 ohm woofer.

Now, you did bridge the connection on the amp, correct?

If so, then your wiring is good, you gain seems to be about right (minus the gain).

What are your crossover settings on the amp set at?

I'd dump the box (or return it if you can). Surely it's tuned very high (38-46hz), and there's not a lot of port volume or port area. Just a suggestion.

mzh29 12-30-2009 08:24 PM

Re: Amp help
 
The amp just has an LPF switch on it, which I have turned on. I had a feeling that maybe I should stick with a sealed box, but I've never had a ported box and wanted to try it out. I'd like to avoid the hassle of returning the box. Do you think it would work if I sealed off the port with like a piece of plexiglass?

Matt 12-30-2009 08:30 PM

Re: Amp help
 
Quote:

Originally Posted by mzh29 (Post 123464)
The amp just has an LPF switch on it, which I have turned on.

Good. Leave that on. That will filter out the higher frequencies and only allow sub bass frequencies to be sent to the sub.

Quote:

Originally Posted by mzh29 (Post 123464)
I had a feeling that maybe I should stick with a sealed box, but I've never had a ported box and wanted to try it out. I'd like to avoid the hassle of returning the box. Do you think it would work if I sealed off the port with like a piece of plexiglass?

The thing with ported enclosures is that it is VERY VERY important that they are designed specifically for the woofer they are housing. This will make or break how it sounds... and given the general consensus about pre-fab vented enclosures, that one is probably awful.

Yes, you could seal the port, but plexi probably ain't gonna cut it.

I'd return it and get this;

http://www.sonicelectronix.com/item_...+-12SQTC-.html

mzh29 12-30-2009 08:50 PM

Re: Amp help
 
Hmmm... I'll have to give it some thought. I think I might try sealing it off first and see if it makes a difference. It looks like it would be super easy with a wood block covered in black carpet. Then put the silver trim piece back on using longer screws to hold it in place. I mean it sounds pretty good. My main concern was the amp, I was listening to some pretty hard hitting songs with the volume cranked.

Just looked on their website, the box is tuned to 42hz for what it's worth.

On the kenwood site it says the sub has a free air resonance of 32hz, does that pertain to the type of ported box it should be in?

Matt 12-30-2009 08:53 PM

Re: Amp help
 
I know I've read on car audio forums that people have had this same problem, I just have never opened the threads - never had this problem. Maybe search around at caraudio.com or diymobileaudio.com

mzh29 12-30-2009 09:07 PM

Re: Amp help
 
Quote:

Originally Posted by Matt (Post 123490)
I know I've read on car audio forums that people have had this same problem, I just have never opened the threads - never had this problem. Maybe search around at caraudio.com or diymobileaudio.com

Is there any way to lower the hz of the box?

Matt 12-30-2009 09:10 PM

Re: Amp help
 
Quote:

Originally Posted by mzh29 (Post 123504)
Is there any way to lower the hz of the box?

Not properly, no.


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