If its a (OEM for example) 6.5 ---> a 4" adapter, yes that very much is possible, you can make your own out of 1/4" thick wood. Its not hard to do at all.
However an adapter to (somehow) fit a 6.5" into a 4" speaker hole is not (in all practicality) possible.
EDIT: And please put Audio & Electronics related threads in the appropriate section, which is a specific child forum of the general automotive section.
Yep the car has 6.5 for OEM and i plan on fitting some 4" which i can get for a real great price. But seeing as i don't have access to MDF or to even get it cut i was hoping someone makes an adapter. Also sorry for putting it in the wrong section i always thought the audio was for the mx6 *shrug*
^ Its all good, its the place for general audio inquiries. To my knowledge you can't buy MDF in 1/4" anyway, but I was talking of simple plywood. I'm sure you do have friends then can cut one. All you need is a simple cut-off saw, or a jig saw, and a 4" hole cutting saw "bit" (usuable in any power drill or drill press) you can get at Home Depot.
the total cost (minus the saw) would be about $14.
You can kiss your bass goodbye with a 4" though, forget about bass-response. 4" speakers can't realistically produce anything below 100-140hz, which isn't even "bass" at all in all reality.
I take it your buying these used...correct? If so, pass and get speakers of the appropriate size. A 4" speaker leans closer to being a tweeter then a midbass driver. If you set on saving money, leave the stock in the car, as the response from the stock 6.5" speakers will likely be better than the 4" you plan on using.
Also, the 1/4" size of MDF in question does exist, it's just not popular. Just to clear up that little bit. However, in any case audio related, your best to start at 1/2" and head up from there.
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