View Full Version : Sub Sounds Bad
04-28-2003, 02:26 AM
I bought a Polk GNX 104 10 in. and put it in a .65 Sealed Q-Logic box. I hooked the sub up to my friends JBL amp which he uses for a 10 in. JBL. I dont know how many watts the amp is, but I think its somewhere between 100-200 rms watts bridged. At very low volume, it sounded decent. At normal volume and high volume, it sounded bad. It made a weird rattling noise and the sub was moving really fast, faster than a normal sub does. I dont know what the problem, and I hope it's the amp so I dont have to take out the sub. Anyone have any ideas?
I put the polyfill in the box, patted on all the sides of the box. Is that ok or should I take it out? I heard polyfill is for boxes that dont match the size of the sub.
First check the enclosure for any gaps around the woofer which will and or may cause it to leak. To get better performance from these subs, I would recommend using a larger enclosure. Look for a internal sealed box volume of 1.0 cubic feet and for a ported enclosure look for a volume of 1.25 cubic feet and tune it using a 4 inch diameter port that is 12 inches in length. If you have any questions regarding these enclosures, call our woofer installation hotline at 800-377-7655 and we will be glad to help.
04-28-2003, 01:40 PM
define the term "the sub is moving very fast - much faster than a normal sub" ?????
there are two "ways" a sub moves (bear with me far as language goes).
1- how far it moves forward or backward - when it bumps, it'll go out a maximum of a certain distance (safely). this is related to its power handling... a 1000 watt sub moves out further than a 200 watt sub. if you try to put too much power on a sub it'll die for one of two reasons ....either you'll fry the electrical part of it... or... the electrical part will hold up and the mechanical part will be damaged because the sub is trying to move farther forward than it is physically capable of.
2- the SPEED of movement -- how quickly it moves forward or backward -- not distance... just rapidity of the oscillations. this is not determined by the amp or the sub -- its determined by the SONG your listening to... the rapidity of oscillaiton is the frequency of the sound being played on the speaker... if you have your crossover set to anything above 100 hertz OR you are not using a crossover, or your crossover is dead, then you're sub is going to try to play "high" notes that it shouldn't be... in which case, it'll move more rapidly until it reaches the top if its frequency range.
the box size is bogus like kim said... you need a much bigger box for a GNX... 1 cube would be a lot better. I had a sub that called for a 0.75 cube box in a 0.5 cube box to test it -- sounded like crap -- built a 0.7 cube box and stuffed a chunk of fill in it and voila it sounds great.
04-28-2003, 06:08 PM
How is it too small when this webpage recommended gettng a.65 sealed enclosure?http://www.polkaudio.com/car/toolbox/subboxplans/gnx104_.65_sealed.php
04-29-2003, 05:32 PM
u know u have a point, thats really odd... i did some snooping and it says the GNX 12 has a recc sealed volume of 1.25 cubes... now... if the 12 is at 1.25, you'd expect the 10 to be at like 1.0 or in that general area.
0.65 is the LISTED spec, but it doesn't "seem" right. maybe it is. I don't think it is though, espeically since kim said 1.0 himself. I've only heard the 12's in 1.25's and 1.0's... the 1.25 was better... still not glowing by any means, but better. i dunno man.. try but think about the x-over thing. 1.0 is probably the right box size, i'd bet 0.65 was a typo.
05-16-2003, 08:19 PM
Ditch the Qlogic box. Thoes are usually made like a pile of sh*t. A good MDF box will be better. I have a GNX 104 in a sealed MDF truck box and it sounds great at any volume. I am guessing that it is the box. Get a good MDF box and ditch the q logic.
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