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ToyPick 9th November 2011 01:11 AM

Just a few questions
 
High guys I'll make it simple I'm starting to be very interested with fiddling with audio but I have more of a technical interest.Basically what I mean is I try to reuse a lot of stuff I find laying around and make it useful.

I have a regular cab toyota truck and there is not much room to fit anything so right now what I have as a setup is a Rockford Fosgate amp hooked to two bridged 6.5 inch woofers each in a separate enclosure.

The woofers are basically "computer" subwoofers that I wired directly through the vent port to drive it with my Rockford amp. One of them is pulled from a Logitech X230 2.1 kit and the other one is an Altec Lansing woofer that I inserted into a home made enclosure to fit the space behind the seats.

The bass output of these two paired is very surprising seeing the small cab space, but the Altec one even though most of the time has a nice sound has a lot of trouble doing lower frequency it will literally distort the sound ruining some of the music I listen to. The logitech one has no trouble it just lacks on higher volume which isn't surprising seeing it's size.

My question to you guys is, if I just order a higher rated more "heavy duty" 6.5 inch and replace it will I be able to solve this issue or am I better off trying to fit a bigger size woofer?

Richard Ellis 9th November 2011 01:36 AM

Just replacing the Altec woofer with a "heavy duty' one won't solve anything. You say you built an enclosure "to fit" the space behind your truck....Frankly it's not quite that simple. Woofers need to be in a correct sized enclosure....not doing so can bring about all sorts of "problems" which probably account for your bad sound. Woofers can be sorted between two types, ported or sealed enclosures. If you can read any model numbers off the Altec you've got in your box.....we here can likely find out a group of specifications for that particular driver.... & tell you what size & type of enclosure it should be in.
The reason the other woofer sounds OK is that someone already did the math to put it in an appropriate enclosure.


__________________________________________________ ____Rick...........

ODougbo 9th November 2011 11:20 AM

1 Attachment(s)
IMO, I would go for the RFFG P2 8" in a sealed box - you won't believe your ears! You can go to their website and look at recommended enclosures.

I did try a few of the 8" woofers in this price range, the RFFG was noticeably better.

These are new the older ones sold 2 for $79.

Rockford Fosgate P2D2-8 (P2D28) 8" Punch P2 2-Ohm DVC Subwoofer/Sub Woofer | eBay

ToyPick 10th November 2011 03:32 AM

Thanks Rick for that reply,

To simplify things I said I had an enclosure that fitted, basically it was another enclosure from another PC Woofer that I fit in the Altec Woofer which was the same size since it was a cheap chinese enclosure and driver.

I added some isolating material until I had an overall pleasing sound.

The distortion I get at low frequencies is not due to the enclosure, because when I have the driver play the same frequency OUTSIDE the box the noise comes from the driver being driven over its capacity at that frequency.

So that was why I'm wondering if I go to a stronger driver that can deal more power if I could partially or completely solve my noise problem, since the enclosure seems to give good performance at lower volumes.

Thanks for the suggestions about the 8 inch sub, but keep in mind I have a maximum of about 9 inches depth, 10 wide and maybe 8 or 9 in height behind the seat. So would a bigger driver suffer from a smaller enclosure?

Richard Ellis 10th November 2011 03:58 AM

Playing music at somewhat high volume levels when you have a driver removed from an enclosure can often times damage a driver....differing types of drivers rely on the sealed air inside an enclosure to control the cone movements, hence the name "acoustic suspension"......using the air to limit the excursion distances (Front to back cone movement) and to dampen out resonances of the cone. A driver cone will have a resonance...similar to a tuning fork....a particular frequency that it will want to 'ring' at....with very little effort to get it 'started", once set it motion, just like a tuning fork...it will be difficult to stop, even when you remove the signal going to it. So we put it in a sealed box to dampen out this "self ringing" effect. Driver cones have a deceptively short distances they are suppose to work within, front to back travel..It's called Xmax...for an eight incher it is some where around 2.5mm forward to 2.5 mm rearward. Drivers can smack into physical limits sound like a rattling sound. Of the two types of enclosures there are roughly two other types of drivers, Home types and Auto types. Home types are low Xmax values, typically, and Auto types with lots of cone travel(Xmax) and are engineered for small box volumes....well within your size limitations. Auto types are generally agreed to not sound as "accurate" as home types. Unfortunately auto types tend to be rather inefficient (Suck up alot of Watts) for the same sound volumes. Hope this helps...

__________________________________________________ __Rick.........

ODougbo 10th November 2011 11:22 AM

Did you go to the RFFG site? It's a one stop shop:

The P2 works in a .2 - .3 box, .23 is recommended.

9"-10"-9" = .28 using 3/4" wood, so there is room.

If I were you, Id be cutting some cardboard and taping up a mock up, to see what I can fit in there.

Again the P2 in a small cab...well it could ruin your ears!


http://www.rockfordfosgate.com/rftec...s-MAN_Rev2.pdf

ToyPick 10th November 2011 03:33 PM

Thanks guys for the help!

I see what you are saying Rick, basically could we set as a hypothesis that my current enclosure allows too much x-travel? Could I add more isolating material to the enclosure to restrict movement sacrificing a little resonance?

As for the RFFG it looks very interesting, though my question is that I Realise there are 2 and 4 ohm versions and it looks like its a dual voice coil... what do you base your choice on when choosing such parameters?

Also, If I pair my current logitech sub which does surprisingly well with the RFFG is that of any use? Or am I just setting a handicap on my RFFG since the logitech just probably wouldn't follow up?
Thanks a lot guys!

Also just a note, I have a second logitech exact same model, I used to think that having two different types of enclosurse AND OR woofers would cover a bigger frequency spectrum giving an over-all good bass but what If I just paired two identical logitech subs together, would I expect better results ?

ODougbo 10th November 2011 04:57 PM

The two versions give you a lot of flexibility,
the double 2 ohm could be wired 4ohm.
or the double 4 could be wired 8ohm.

I believe they make single voice coils models also.

You would be very impressed with a 8" car sub, I had one in a truck cab, it made the widows and mirrors shake.

sreten 10th November 2011 05:10 PM

Quote:

Originally Posted by ToyPick (Post 2776642)

Also just a note, I have a second logitech exact same model, I used to think
that having two different types of enclosurse AND OR woofers would cover a
bigger frequency spectrum giving an over-all good bass but what If I just
paired two identical logitech subs together, would I expect better results ?

Hi, No it it doesn't work like that and yes. The logitech would handicap the P2. rgds, sreten.

ODougbo 10th November 2011 05:16 PM

The P2s have a very nice tone about them, not a one tone wonder by a long shot. Just get one, and enjoy it. I bet you can find a last year's model on sale.


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