AMP/SUB Help!

[jbizzle 5,000+ posts]

I have a question, I connected my sub and amp, while it was 4 ohms, now I connected it this way: http://www.crutchfield.com/learningcenter/car/subwoofers_wiring.html?imageID=1DVC%5F4%2Dohm%5Fmono But I didn't notice a major difference. At 4 ohms my amp is pushing 500 RMS watts. And 2 ohms my amp is pushing 1000 RMS watts, can anyone explain please?

AMP:

http://www.mtx.com/caraudio/products/amplifiers/thunder81001.cfm

SUB:

http://www.mtx.com/caraudio/products/subwoofers/thunder9500.cfm

BOX:

http://www.mtx.com/caraudio/products/enclosures/sledgeHammer9500.cfm

# T9512A

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[jbizzle 5,000+ posts]

bump

 

[kross 10+ year member]

Double the power = 3db increase in SPL. Also, make sure the gains are set properly.

 

[jbizzle 5,000+ posts]

Well my GAIN is set up all the way.. I'm not that smart with this but why don't I hear a difference?

 

[dyohn 10+ year member]

Well my GAIN is set up all the way.. I'm not that smart with this but why don't I hear a difference?

Your gain should never be "up all the way" for a daily driver. Learn how to set it correctly if you want your speakers to last for a while. The previous answer was the correct one: double power to the same speaker = +3db, which may or may not be that noticeable. Running the amp with a 4-ohm load is much better for it, by the way, as it will run with less noise, less distortion and less heat. And man, set your gain properly.

 

[jbizzle 5,000+ posts]

Your gain should never be "up all the way" for a daily driver. Learn how to set it correctly if you want your speakers to last for a while. The previous answer was the correct one: double power to the same speaker = +3db, which may or may not be that noticeable. Running the amp with a 4-ohm load is much better for it, by the way, as it will run with less noise, less distortion and less heat. And man, set your gain properly.

Well the guy from the store set my amp, and I checked it and its ALL the way up. My bass boost is not all the way up though, is there a way you guys can tell me where to set it at? Because I don't want to **** up my sub if you understand.

 

[kross 10+ year member]

Sure. It's actually fairly easy with an inexpensive multimeter, and a test tone CD. You can do it by ear, but using a multimeter is more accurate:

http://www.caraudio.com/forum/showthread.php?t=164826

 

[jbizzle 5,000+ posts]

Thats pretty hard :\ Should I take it back to the store and have him set it up for me? Because the guy who had did it WORKED for the guy and the OWNER who does most of the stuff didn't do it.

 

[jbizzle 5,000+ posts]

Theres no thing to tell me WHAT to set the amp shit at? I'm going to go take a picture of the amp.

 

[kross 10+ year member]

Not really hard. Disconnect the sub speaker wire from the amp. Pop in a test tone CD (you can download and burn one for free), pick a 50Hz 0db tone, set it to repeat, turn the volume up to about 3/4, and measure the voltage output of your sub amp. Adjust the gain until it says 44.7 volts (for 1000wrms @ 2 ohms). You're done.

Oh, and turn off bass boost. All it does is add distortion.

If that sounds too hard for you, then I guess you have no choice but to take it back to the shop and have them do it. But they are the ones who turned it all the way up to begin with. But if the owner will do it, instead of the other guy, maybe he knows how to do it properly. But you'd think he would have trained his employee how to properly set gains.

By the way, I just reread your original post. You said it was originally wired for 4 ohms, now it's wired for 2 ohms. This has me confused. A 4-ohm dual voice coil sub cannot be wired for 4 ohms, unless you only had one voice coil hooked up before. How exactly was it wired before? Was it the same amp?

 

[jbizzle 5,000+ posts]

Before it was connected directly to these coils: http://img263.imageshack.us/img263/3300/asdasdkg7.jpg

Now, there are other slots next to them, and I connected it like this:

http://www.crutchfield.com/learningcenter/car/subwoofers_wiring.html?imageID=1DVC%5F4%2Dohm%5Fmono.

I don't have dual coils, only 1 positive, 1 negative, then those extra ones next to it. Doesn't look like coils to me. Let me see if i can get another picture.

 

[kross 10+ year member]

So you're saying it was only wired to 2 of the 4 terminals on the sub?

 

[jbizzle 5,000+ posts]

http://car-audio-video.info/blog/mtx-thunder-9500-back.jpg

Then there are those 4 holes in the side, 2 positive, 2 negative. But only 1 positive and 1 negative voice coils.

 

[jbizzle 5,000+ posts]

And yes, it was the same AMP.

 

[kross 10+ year member]

Which model sub do you have? Is it the T9515-44 or T9515-04?