Porting trunk

[mcss383]

sheesh people. its been established for the past 35 posts that he shouldn't cut the ports to the trunk.

PPI: Its broader than what I did, and your point is???? He wanted to know some ways to get it a little louder, I gave him one. One that is free and requires about 5min of his time.....No friggin joke a ported box tuned for max SPL will net louder output than removing 4x10's with a sealed box....that was never a point of comparison.

In car response will boost it even more, our peak for cabin gain is somewhere in the upper 50's.


How in the world did this post get to where it is????????

 

[PPI Typhoon]

Originally posted by mcss383
No friggin joke a ported box tuned for max SPL will net louder output than removing 4x10's with a sealed box

45Hz is hardly SPL porting. Most of the competitors are running 55-65Hz tunings. 45 is actually quite respected. Typically yields a 3dB hump (standard for the ported enclosure). But with his speakers, they just happen to have a better response.

 

[Audiowizard]

Originally posted by mcss383
How in the world did this post get to where it is????????

I am no expert here, just an audiophile enthusisast with 12 + years experience! But............. There is alot of input from members on this thread that consists of "opinions" and "facts" and the only thing that we can agree on is "that we all agree that we disagree"!!

 

[mcss383]

No 45Hz wouldn't be an optimum SPL tune, you are right. But with a 7db bump its far closer to a SPL tune than a SQ tune, thats all i meant.




Yeah Eddie, I think its safe to say we agree that we disagree. lol

 

[Joe Tiano]

...and WE ALL agree that...most of us LISTEN to music on our systems... NOT test tones!..and onother opinion of mine is the bass box programs out there...as power increases...and voicecoil temperature increases the CHARACTERISTICS of the driver/box combonation WILL undergo CONSTANT DYNAMIC CHANGE.....with that being said..i'm just an amateur ....and my ears still work!...agian NOT flaming anyone!...just curious

 

[johnjj728]

i think ive got my mind made up....gonna port the box to 35 hz...with 2 3 inch ports that are 8.4 inches long and then im gonna take the insulation out behind the seat and leave the audiobahn 4x10's because i like the rear fill. sound like a decent idea to everyone??? and possibly make a hinge to fold down the rear seat if thats possible?

 

[mcss383]

folding rear seat

its possible, I have seen pics of people who have done it, but haven't found where someone said how they did it. I don't think it would be too hard, but would require lots of thought and planning to make sure its still secure and safe.

 

[mcss383]

Originally posted by Joe Tiano
...and WE ALL agree that...most of us LISTEN to music on our systems... NOT test tones!..and onother opinion of mine is the bass box programs out there...as power increases...and voicecoil temperature increases the CHARACTERISTICS of the driver/box combonation WILL undergo CONSTANT DYNAMIC CHANGE.....with that being said..i'm just an amateur ....and my ears still work!...agian NOT flaming anyone!...just curious

That is very true, but I believe that the char's don't change too much and if the 'static tune' is spot on all will be well. PLUS, like you said, we listen to music and not test tones so the vc's don't really heat up too much unless your getting crazy with the volume control and bass CD's. lol

 

[salvageV6]

How hard would it have been to pop out the 4 x 10's and take a few measurements.

Oh well back to arguing about shoulda woulda coulda....

 

[johnjj728]

i took out the 4x10's and listened to it but it wasnt much of a difference...little louder but not much

 

[Audiowizard]

Originally posted by johnjj728
sound like a decent idea to everyone??? and possibly make a hinge to fold down the rear seat if thats possible?

I seen a local at a sound-off a few years ago with an SS Monte Carlo and he built a folding rear seat but everything was hand built to make it work. He had 4 12" subs in a "W" shaped box and that thing was "INSANE".

He had it where it would unlatch at the top and the bottom pins could be repositioned up higher so when the seat folded, the hinge point would not bind with the top and bottom of seat. Just about anything is possible with imagination, fabrications skills, and a little bit of green back!!


I think we have beat this topic to death with "opinions" and all!!!

 

[salvageV6]

Well if you could hear the difference it was most likely 2-3 db.

A significant improvement eh?

A real semi-easy semi-scientific test would be in order.

Especially in predicting acoustical changes in a difficult environment.

Okay back to armchair quarterbacking.

 

[Joe Tiano]

sorry..my last post kind of a cheap shot!....but..the thiele/small calculation methods are based on a ...1w-1meter ..LOW level input...and...a manufactures PUBLISHED spec!.. .do my subs get more than 1 watt?????....and is the speakers published specs correct??? ....AND now were ready to put that box in a car.... ....john...just unhook your sub box....and try another...easy non scientific testing ....use your ears!...our buicks have a huge trunk!....the simple closedbox speakersystems(IB or AS), thats infinite baffle or air suspension....SIMPLY HAVE LESS trade off's....compared to VENTED designs with 24db/octave rolloff...a closed box with the same f3..WILL have MORE low bass AND BETTER transient stability... happy listening! joe

 

[Audiowizard]

Originally posted by Joe Tiano
sorry..my last post kind of a cheap shot

Thanks for the apology!

 

[Yedi]

sealed box?

If the subs are in a sealed enclosure right now.......that's THE least efficient enclosure subwoofers can be in. You WANT a ported enclosure if want loud, and deep bass. Typically a sealed enclosure will only play down to 55 Hz before rolling off (your power handling rolls off too). Then in ported enclosure, you can play down to the tuned frequency generally without any problems......and has a much lower -3dB point. So if you take the enclosure you have........tune it to 40 Hz with a port......you could get as much as a 3dB increase in efficiency......basically the same increase you would get from doubling your amplifier power. AND you get a better power handling into the lower frequencies. If you're a rock kinda guy......tune from 40-45Hz. If you're a rap/hip hop kinda guy, tune from 30-35 Hz. Keep in mind that the higher you tune, the more SPL you will yield. (It will play higher volumes)

I'll agree about a ported enclosure "hitting harder", and being louder, but my experience has been to go with a sealed enclosure. My first system was in a 93 Jimmy. It was an MTX thunderpro box with 2 12's, 3" midrange, and two horntweeters. The box was ported, huge ports. It was loud, hit very hard, and the lows were descent. But since then I've built many boxes and sealed is the way to go. The sound is much clearer and the lows will definetly hit lower ( MY 2000 dakota that had two MTX 8000 12's in a huge sealed box played some of the lowest bass around, there is no way a sealed box could havce been louder than that. Than again I've never messed with port calculations for enclosures, so I'm just telling stuff from my experience. From what I know a sealed enclosure is better for a woofer because there is a pressure behnd the speaker which will make it harder to bottom out. With a ported enclosure air is moving out ( sound is too, which is good) but the speaker will move easier. Just my opinion here......


And Whats wrong with 4x10's?? Thats what our cars were made to fit and there are some real good 4x10's out there. I use mine for rear fill highs, I have the perephial bass blockers on them and they sound extremely clear, not saying their the best out there but pretty damn good. I've enjoyed reading this thread and I'm just stating opions here, not saying someone is wrong......

Later.

 

[PPI Typhoon]

Re: sealed box?

Originally posted by Yedi
I'll agree about a ported enclosure "hitting harder", and being louder, but my experience has been to go with a sealed enclosure. My first system was in a 93 Jimmy. It was an MTX thunderpro box with 2 12's, 3" midrange, and two horntweeters. The box was ported, huge ports. It was loud, hit very hard, and the lows were descent. But since then I've built many boxes and sealed is the way to go. The sound is much clearer and the lows will definetly hit lower ( MY 2000 dakota that had two MTX 8000 12's in a huge sealed box played some of the lowest bass around, there is no way a sealed box could havce been louder than that. Than again I've never messed with port calculations for enclosures, so I'm just telling stuff from my experience. From what I know a sealed enclosure is better for a woofer because there is a pressure behnd the speaker which will make it harder to bottom out. With a ported enclosure air is moving out ( sound is too, which is good) but the speaker will move easier. Just my opinion here......


And Whats wrong with 4x10's?? Thats what our cars were made to fit and there are some real good 4x10's out there. I use mine for rear fill highs, I have the perephial bass blockers on them and they sound extremely clear, not saying their the best out there but pretty damn good. I've enjoyed reading this thread and I'm just stating opions here, not saying someone is wrong......



Later.

I'm not saying sealed enclosures are BAD, but rather not nearly as efficient as a ported enclosure. No matter what application, a sealed enclosure is not as efficient as a ported enclosure. Why? That port is another source of sound waves. This can effectively give a 3 dB of gain. This is quite noticeable. Not to mention, you have a MUCH better frequency response with a ported enclosure over a sealed. AND, because you have full power handling down to the tuned frequency, this gives you cone control into the lower frequencies. This will allow you to put more power to lower bass and keep the cone controlled, unlike a sealed, where the cone excursion just inceases as the frequency decreases.

I've heard a lot of sealed enclosures that sound good too. But if you take the Thiele/Small parameters for a speaker, and properly design a ported enclosure for the very same sub, it will outperform a sealed.

Here's the sub in a sealed and a ported enclosure. While the sealed plays down to 35 Hz (very respectable), the power handling rolls off at about 45.55 Hz, where the ported handles full powe down to 30 Hz, and plays down to 25 Hz.

Here's the diagram on that.

 

[Yedi]

PPI Typhon Thanks for the info, after listening to you you've made me thuink about porting my system in my regal. It's just interesting to hear stuff from someones else point of view, let alone to see the proof. Later.

 

[PPI Typhoon]

Originally posted by Yedi
PPI Typhon Thanks for the info, after listening to you you've made me thuink about porting my system in my regal. It's just interesting to hear stuff from someones else point of view, let alone to see the proof. Later.

Well, it not only comes from years of working in the industry, but also me destroying a few cars with my stereo systems. Back then it was a few Fieros (did two 15's in a Fiero...woohoo). But I'd just hate to see someone cut up a Buick if they didn't need to. Cutting up your car is just cutting corners (no pun intended). 85+% of your sound is dependent upon your enclosure design. The rest are vehicle acoustics. But I've seen people win their local SPL competitions, full trunk, no holes cut. But they have the perfect enclosure back there.

As far as the 4x10 issue, if you think about it, the voice coil is round, and the odd shape of the 4x10 makes it distort easily under moderate excursion of the woofer cone. If you use a strobe light and a test tone, you can see it. Pretty weird. And distorted cone=distorted sound. But if you don't see that, you probably couldn't tell the difference anyways. But that's why you see few companies actually do 4x10's. You don't see the major SQ companies doing it, but you will see Jensen, Pioneer, etc do it as they want to cater to everyone.

 

[Joe Tiano]

85% of your sound?????....lets see here... 100hz-20...yep thats all you need to win a local spl show!....i'm not flaming here, as i used to show up at my local SPL shows..0-100 watt class...with 1, XTR 15 dvc in a bandpass box...and it WAS a BOX indeed!..powerd by a bridged 250hcca orion...100hz up was handeld by a junk clarion cd player with maybe 10w on a pair of morel integra 6.5" coax...yep 3 speekers.. NO EQ...139dB..and a response curve(RTA) of 34-38..(based on the iasca 40 point RTA system)...depending on where the mike was placed!...it was loud...looked good to the RTA!....looked good to the RTA!..looked good to the RTA..and to think...it all only took 30 min to install!..that was back in 93' tho.and the car had better sound quality than most of the cars competing in sound quality...with NO! emphasis on install ..just a magic box....just make the machine happy!...(RTA) joe

 

[Audiowizard]

Originally posted by Joe Tiano
yep 3 speekers.. NO EQ...139dB..and a response curve(RTA) of 34-38..(based on the iasca 40 point RTA system)...

You were lucky Joe! I had to spend a few hours tweeking my SPL blazer's Symmetry set-up and 4 amplifiers for:

4 18" RF subs
2 8" RF mid-bass
4 6" RF mid range
2 3.5" RF mids
2 Polk tweets
2 Soundstream tweets

I actually scored 40 points (a perfect RTA) but the judge said I was a half db off and gave me a 39 and that "one" point put me in 2nd place!!!! But.....I always had fun and didn't let it bother me. That was the good "ole" days of when SPL was "king" in the sound offs!

Here is a link to some of the pics of the "BEAST"

SPL Blazer

These subs were only "inches" from my head!!