non-fiberglass spare tire/wheel sub
 

Use the spare tire/wheel itself as the enclosure- no fiberglassing required. Just seal the bottom with foam weatherstripping where the wheel makes contact. the rubber tire will seal the top (peace of thick plywood). Cut a hole for the woofer. Crank it down with nylon straps/ratcheting mechanisms. I threw the carpet right on top. The ratchet mechanisms propped it up so it wouldn't touch the speaker.

I got a set of Polk audio db6501 and two amps. One for the components and one for my 10 in. Sub.

When the amp is off I can hear a high frequency sound coming from the tweeters. (Only when the car is started, if it's just on the ON position there is no high frequency sound) It's really annoying.

When I disconnect the tweeters from the crossovers there's no frequency sound anymore. I just find it strange that it's making this sound even when I have both the radio and amp off. It may be worth while mentioning that my sub was getting some engine feedback so I checked my ground location and there was some paint so I scrapped it off and that solved it. (I just checked my ground for my component amp and it's also on metal with no paint)

I used a set of $10 RCA's from Amazon to connect the radio to my subwoofer amp and everything sounds good, so I don't think I can contribute the high frequency sound to cheap RCA's for my components amp. (The brand of RCA is Tsunami)

Does anyone know what is causing this and how I can fix it??

Its a ground issue, for sure. Your amps ground wire should be the same gauge as your power wire. It also needs to be very secure, and paint free. Sometimes its as simple as moving it an inch from where you have it to get better contact. Seatbelt anchors are typically what I shoot for. Heavy, and secure.

I appreciate the response.

I tried two more different locations in hope that it would solve this issue but was unsuccessful in doing so. (Both the ground and power wire are the same gauge)

Any other thoughts?

I would check your rca cables, be sure they are not damaged at all, and try to keep them away from your power wire. Are your amps contacting metal anywhere? they should not.
Be sure your power wire is tight as well. If all looks good, last thing I would check is your input gains may be cranked too high. How did you set them?
If all else fails, try grounding the Outer leads of your rcas to the chassis as well. (not the most likely cause, but it is possible.....

:wtf2:You cant be serious......... What is the volume of your "enclosure"? Does it match your subwoofers T/S Parameters?

I'm reminded by his post of all the awful DIY jobs I get coming into the shop for me to fix.

I've got a pair of DB6501s in my car and now I'm looking to upgrade by getting an amp and a sub.

Which do you guys recommend for a complete system? I'm not too crazy on bass or anything, I would just like a bit. I'm also hoping not to spend more than about $300 for the amp and sub.

you should look into a powered sub

RonRizz,

I just bought these RCA cables Monster MPC I202 2C-4M Low Noise 2-Channel Car Stereo RCA Cables (4 meters):Amazon:Car Electronics
In hopes that I can get rid of that high pitch sound. My current set of RCA's that are going to the amp for my component speakers is running on the passenger side which is also where my power wire is. (Maybe this is where it's picking up all that "junk")

I'm going to run these new monsters along the drivers side which also currently has my RCA's for my sub amp. Hopefully this will work. Only concern is that I don't know how I'm going to squeeze another set of cables through the "side skirt" by the seat. From what I can remember it was awfully tight.

Prior to changing them out, try this........
With stereo OFF, disconnect rcas from amp running components. Turn stereo on, and see if noise is still there. If it IS, its coming from the amp (ground issue) and not the cables. If its NOT, likely your cables are the culprit.
Turn stereo back OFF, and reconnect rca cables at amp, and disconnect at Radio. Turn back on. Noise? if so, its your cables for sure. if not, your getting noise at your radio (change that ground)
Basically, what were doing here is working our way up the chain, and isolating each individual component one at a time. Its the best way I know of to determine where noise is being introduced into the system.

Thanks!!
I'll give everything you said a shot and I'll keep you posted