Technical Subwoofer Question/Comparison

[Fastr 10+ year member]

Ok, I have a couple questions about two different subs I have (I want to understand better about what I have and why it has reacted the way it has).

Ill try not to get to confusing in my descriptions and questions //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

First, Ill explain the first sub: Rockford Fosgate 12" Punch Power (the old school ones. Ill attach the spec sheet from the 90s)

It was a friend of mines sub and I ended up with it. When he bought it, the audio place he got it from said they built the "optimum" enclosure for it. It was 2 cu/ft sealed. To be honest, its one of the best sounding subs Ive heard, especially in the really low hz. I later built a 1.68 cu/ft box sealed for it (for space saving reasons) and filled it with polyfill. What happened was on the higher bass notes, it didnt punch as hard and tight, but the lower notes were so much deeper and louder it was quite noticable. (this is exactly opposite of what I expected from a smaller box!) I had used both boxes in the same car with same amp for comparison.

- Based on the sub specs, is this what should have happened?

- What would the "ideal" sealed box size be? (The owners manual doesnt even list a sealed box size, only a ported box size of 2cu/ft.)

I now currently have a Alpine Type R in a sealed enclosure (about 1 cu/ft) in my Lincoln LS. It punches hard and is quite loud, but doesnt play the low notes nearly as deep or as accurate as my RF sub did.

-How do these two subs compare?

I am all about hitting the real low notes with SQ, not worried about SPL at all (In that case, Ive never heard a half decent sub that Couldnt go loud enough to damage my hearing)

I now know, thanks to this awsome message board, that the Type R was totally the wrong choice for SQ. It doesnt sound that bad really, but I feel I am really having to down its performance just to get that SQ.. (hence the sealed box)

Any advice on what to do and which sub I should go with would be greatly appreciated! (And if necessary, I may just say F it and buy a new sub, LAF. There are alot of great subs listed on this site that I had never heard of before....)

ps - ok, cant skrink the pdf down small enough to fit on here..

RF sub specs are:

Magnet Wt: 116 oz.

Freq Range: 25-1500 hz

Re: 3.4 ohms

fs: 25 hz

Qms: 2.89

Qes: .28

Qts: .26

Voice coil Diam: 4.00"

Voice coil Inductance: 1.3 mH

BL: 15.4 Tm

Linear Excursion: .24" (6.2mm)

SPL: 91.0 dB W/m

Click to read more...

 

[BEAVER.989 10+ year member]

Type R's aren't known to do so well in sealed enclosures. A nice ported box, tuned low should hammer out the lows much better.

 

[skateboardkid 10+ year member]

Well if you were to put the type R in a ported box tuned in the low 30's I bet you would not have to change your sub out.

Something like 1.75 tuned to the low 30hz like 33 would bring back the lows that are missing with this woofer in a sealed alignment and really bring this woofer to life.

About how much power are you sending it?

you got plenty of trunk space just make the box go across the entire back on the seat side and it wont have to be very deep.

just my 2 cents.

 

[Fastr 10+ year member]

Good idea.. I will try building the ported box and see how that sounds.

I see several plans that look interesting.. 2@29hz, 2@30hz.. there is a 1.65@28hz.

-What would be the difference be between these designs? (I dont know much about the size/vs tuning freq. and how it affects the sound)

(I have the 2 coil 4ohm sub running in parallel, so my mono Excelon amp puts out 600w rms @ 2ohms. I should have bought the 2 ohm version, as my amp will go 1200@1)

Thanks for the help!

 

[Fastr 10+ year member]

Well heres an update..

I built a 2cube box tuned@30hz. Big difference for the Type-R. People are right when they say it will actually have Better SQ in a well built ported box. The lows are pretty crazy now, but I do see why peeps say this sub is LOUD but not really a great sound still.

I put my old RF power 12" in the ported box. Not quite as loud, but just has a better deeper bass sound. Hard to put into words.

I then went ahead and built a new 1.75 cube Sealed box for the RF sub. This old thing just sounds fantastic in a big sealed box. Not quite as loud as the ported Alpine on the real deep lows, but surprislingly close! And sounds much better Everywhere else in the freq. range.

I have more in car testing to do, but I think the old sub SQ is so much better Im going to have to go back to it. (Even though its only a 1 coil 4ohm sub, the 4" voicecoil and the 91db sensitivity seem to keep it real close loudness wise to the Alpine). Ill post a final update and pics when Im done.

Jer

 

[Hundreth 10+ year member]

Sounds to me like you had a leak in the smaller sealed box that you built...

 

[Fastr 10+ year member]

No, no leaks. The pieces were all CNC routered (at work) //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

I glue, screw, caulk the seams, then spray the inside with sound deadner.