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View Full Version : Having a very hard time getting help. PROS ONLY!



mendon mafia
11-27-2009, 01:29 PM
ok so before i talk about my enclosure lets talk about what could cause the "symptoms" that i am having with my subs.

Subs can take all the power in the world below 40hz. between 40-50 its a little iffy and above 50 my subs are completely out of control over extending and distorting like mad. BTW i have 2 12" rd alpha v3/v2's.

i realize that the subs should hardly move when playing at tuning but the subs should move more below tuning than above right? all my problems are above tuning. even below tuning the power handling is exceptional and no distortion.

On the song hypnotize by young jeezy the 2 low notes (34 and 37 IIRC) absolutely kill and i can crank the volume all the way up with no problems at all. They keep getting louder and sound clean doing it. but when the high note hits (51hz IIRC) the subs distort terribly and sound VERY bad and move way farther than on the other 2 notes.

So what can cause the problems im having?

PLEASE HELP.

ok so now that you have thought about that for a minuite i can tell you i hav an atomic 3000.1d amplifier, and my enclosures spec out to 2 cubes net tuned to 37hz.

heres some pics of the box, the dimensions are 18.5 wide, 13.5 tall, and 31 long, the port is 4" wide x 12" tall. The port wall lengths are 26.25 and 8

The RE calc says its 2.329 cubes @ 34.46hz but that calc doesn't factor in the double front baffle or driver displacement so thats how i get my numbers for volume and tuning.

http://i837.photobucket.com/albums/zz297/Mendonmafia/101_0604.jpg
http://i837.photobucket.com/albums/zz297/Mendonmafia/101_0605.jpg
http://i837.photobucket.com/albums/zz297/Mendonmafia/101_0608.jpg

CRXBMPN
11-27-2009, 01:31 PM
my old subs used to unload like a bish well over tuning frequency, they go WAAOOOOWWAAAAOOOOOWWAAAAAAAAOOOOOOOOWWWWWWWWWWW and look like they are hovering up and down lol...

Supergumby5000
11-27-2009, 01:32 PM
1) thasa big port for one sub

2) set your filters on your amp correctly

3) check headunit equilizer/filter settings

CRXBMPN
11-27-2009, 01:33 PM
1) thasa big port for one sub

2) set your filters on your amp correctly

3) check headunit equilizer/filter settings

i cant see the pix but he says he has two 12's...

turn the high pass down a bit too, or maybe steepen the crossover if you can on the amp (mins is either full, 12db/oct, or 24db/oct)

hornedfrog1985
11-27-2009, 01:34 PM
3000 rms on a single alpha?

He says he has a v3/v2, and only shows one sub. I assume he switches them out or whatever.

altoncustomtech
11-27-2009, 01:35 PM
Pro... no...... experience.... yes..... sounds to me like you're plain and simply overdriving the amp or having voltage drop issues..... when playing near tuning frequencies you're impedence rise is in the optimal range for the given system and it's happy... once you rise above it you have trouble..... another thing that isn't helping anything is trying to run that much power through that little bitty speaker wire to your subs.... the wires are adding to your impedence problems as well.....

that's my .02.... right or wrong that's where I feel you're troubles are coming in comparison to your expectations of the system....

mendon mafia
11-27-2009, 01:46 PM
ok to clarify all the problems i have 2 seperate boxes which i run BOTH at the same time usually. the specs given are for one box. so multiply by 2 and there ya go.

My amp is used for both subs. wired down to .5 ohm. (1 ohm when im using 1 sub) problem still happens either using 1 or 2 subs.

voltage drop is not a problem i dip into the mid 12's at the lowest. got a 200 amp alt 2 spv70's and a stock batt. only 1 run of 1/0 tho for pos and ground. but as stated before my voltage drop isint that bad.

all my filter and eq settings are set correctly. flat on the eq. filter on the hu is set at 80hz, filter on the amp is probably at 70. If i cross down to 50 i will have no output between 50-80 hz, my momo components are nowhere near as loud as my aplhas. and dont really start hitting until about 80-100hz. (I need speaker pods my doors **** for sealing)

My speaker wire is 10 gauge and i have separate runs for each woofer directly from the amp. the wire shown was just for testing.

Imp rise might be a very likely cause but how do i get around this. never had this problem before. and ive built tons of boxes and systems. non having this large of port area though. but thor and all those other guys with big ports dont have this problem either so idk.

altoncustomtech
11-27-2009, 02:05 PM
ok to clarify all the problems i have 2 seperate boxes which i run BOTH at the same time usually. the specs given are for one box. so multiply by 2 and there ya go.

My amp is used for both subs. wired down to .5 ohm. (1 ohm when im using 1 sub) problem still happens either using 1 or 2 subs.

voltage drop is not a problem i dip into the mid 12's at the lowest. got a 200 amp alt 2 spv70's and a stock batt. only 1 run of 1/0 tho for pos and ground. but as stated before my voltage drop isint that bad.

all my filter and eq settings are set correctly. flat on the eq. filter on the hu is set at 80hz, filter on the amp is probably at 70. If i cross down to 50 i will have no output between 50-80 hz, my momo components are nowhere near as loud as my aplhas. and dont really start hitting until about 80-100hz. (I need speaker pods my doors **** for sealing)

My speaker wire is 10 gauge and i have separate runs for each woofer directly from the amp. the wire shown was just for testing.

Imp rise might be a very likely cause but how do i get around this. never had this problem before. and ive built tons of boxes and systems. non having this large of port area though. but thor and all those other guys with big ports dont have this problem either so idk.

sounds like you have most all things covered.... imp rise problems would require a rebuild of the box I would imagine.... there's a few good books like "Bullock on Boxes" that can explain imp rise in box design, you might look that one up for reference purposes.... otherwise I'm gonna stay out of the rest of the discussion as anything else I would suggest seems to be covered and my understanding of imp rise is pretty basic at this time.... Good Luck man, hope you get it figured out without too much trouble ahead...

mendon mafia
11-27-2009, 02:18 PM
Ok so i just took a vid so yall can see my problems. its uploading to youtube should be about 20 minutes.

I took the vid using only 1 sub and running just off the alt and stock batt. my voltage only dips down to like 13 though.

you can clearly see how much farther the sub moves on the high note than the lows. not sure if you can hear the distortion or not but you can imagine.

mendon mafia
11-27-2009, 02:36 PM
3000 rms on a single alpha?

He says he has a v3/v2, and only shows one sub. I assume he switches them out or whatever.

o and btw by v2/v3 i mean idk which they are. they were told to be v2 by steve miller but as soon as i got mine other ppl started calling them v3. mine have the ti former, 55mm fw coil and a probably all of the same features of the v3's not sure what the diff is other than that anyways. these were supposed to be able to take 2kw rms. Ive actually fed one of them nearly all 3kw and it did take it as long as it was a low note.

mendon mafia
11-27-2009, 02:38 PM
VID
http://www.youtube.com/watch?v=IVc89LdX110

@ 1:10 in i turn it up more so that it starts distorting. Before 1:10 its still clean sounding.

bubbagumper6
11-27-2009, 02:56 PM
I see the problem...it's those gay *** led's you have under your dash :fyi:

spltuscon
11-27-2009, 02:59 PM
Your net volume is 1.93 and your tuning is 38.7, so your numbers are a bit off. The RE calculator ***** so I would find a different one if I were you.
That aside...you can still push your subs past their limits above tuning when you're giving them a lot of power. Have you checked to see if your box has a leak or a weak seam somewhere? Could be frequency dependant or something....
You don't have loudness or any other form of bass boost/bbe on do you?

mendon mafia
11-27-2009, 03:08 PM
Your net volume is 1.93 and your tuning is 38.7, so your numbers are a bit off. The RE calculator ***** so I would find a different one if I were you.
That aside...you can still push your subs past their limits above tuning when you're giving them a lot of power. Have you checked to see if your box has a leak or a weak seam somewhere? Could be frequency dependant or something....
You don't have loudness or any other form of bass boost/bbe on do you?

eq is on flat. bass boost is off. loudness is off. all bass setting on hu are at 0. gains set using dmm.

Box was built using gorilla glue and definitely does not leak. This is like my 10th enclosure build so im not a novice and ive never had a problem like this. I guess i need to try a new box.

I dont think im overpowering the sub considering my voltage drop and the fact that im only using my stock battery in the vid.

How do you figure the measurements you calculated? i was think more around 2.1 and 37 hz

mendon mafia
11-27-2009, 03:33 PM
I see the problem...it's those gay *** led's you have under your dash :fyi:

there under my seats too so theres no shadows and i got the rear lit up too 6 strips in all still need to hide them a little better.

lol and dont hate just cuz you havent installed yours yet ;)

mendon mafia
11-27-2009, 03:57 PM
I think i may knock out the short port wall and then add another port wall 26.25" long This will decrease the port area 39" for each box and should increase the volume quite a bit. Hopefully this will increase the efficiency in the low end and lower it in the top end.

sound like a good idea or no?

spltuscon
11-27-2009, 04:09 PM
The numbers aren't really that critical in this case so I wouldn't worry too much about it. Your port is pretty big for that volume so that's probably not helping....but by itself probably not enough to matter. Gorilla glue ***** for box building though...I know its strong as hell, but it needs moisture to activate which isn't good for the mdf and it swells as it cures which tries to push the joint open. Titebond II is the best glue for boxes. I'm not familar enough with that sub to say if you were overpowering it, but your voltage drop is not that significant so you're still feeding it a lot of power above tuning. Most subs start to distort with a lot of power when you get well above tuing. Don't forget that the 1500w rating is just thermal power handling, not mechanical and with no reference to frequency and tuning. It might be just fine in a different box though. Maybe cut down the size a little and with less port area.

CRXBMPN
11-27-2009, 04:23 PM
Gorilla Glue was the single worst purchase I ever made for anything. Ever.
I stand by my idea that its unloading in those frequencies and your pressure in the box is more ideal at the "non distorting" levels/frequencies.

dt053
11-27-2009, 05:21 PM
A few things to try... but sorry not a pro.

Make sure your amp isn't clipping... your system is more efficient around the tuning frequencies... check it with a O scope.

Have you tried closing the port and seeing if it still distorts?

When the sub unloads, can you tell if it seems to move in one direction more than another?

Have you swept it with test tones and watched the reaction as you move up in frequency... is there a frequency where is stops?


With frequencies above the tuning frequency, can you push the sub inward and have it lock into that position?

What I'm getting at is: does the sub have a dynamic DC offset?

The DC offset could be caused by something as simple as the port geometry... Remember the sub will pull in air not only from right in front of the port but also the sides. which causes the air velocities to be different...( a very good reason to flare or radius a port) this also happens on the inside of the enclosure. If the sub pulls, or pushes air differently, then a DC offset is created and the sub can move more in one direction than another... the harder you drive it the worst it can get.... as the port becomes more restricted when it you try to push more air through it the tuning can change.

If the VC is off center it can cause a DC offset, and if the suspension isn't linear it can cause the sub to move to it's minimal during operation.

Not sure if any of this is your problem but putting my 2cents out here.

dT

mendon mafia
11-27-2009, 05:23 PM
The numbers aren't really that critical in this case so I wouldn't worry too much about it. Your port is pretty big for that volume so that's probably not helping....but by itself probably not enough to matter. Gorilla glue ***** for box building though...I know its strong as hell, but it needs moisture to activate which isn't good for the mdf and it swells as it cures which tries to push the joint open. Titebond II is the best glue for boxes. I'm not familar enough with that sub to say if you were overpowering it, but your voltage drop is not that significant so you're still feeding it a lot of power above tuning. Most subs start to distort with a lot of power when you get well above tuing. Don't forget that the 1500w rating is just thermal power handling, not mechanical and with no reference to frequency and tuning. It might be just fine in a different box though. Maybe cut down the size a little and with less port area.

its 2k thermal according to steve not that it matters much. but so you think i should make a smaller internal volume box? like 1.5 cubes or somthin?

I also free aired a sub to see what happens then and it moves about the same at the high (51hz) and the 37 hz note for hypnotize but the 34 hz note moves less. and actually the sub moves more in the box on the 51hz note than in free air.

im almost positive its the box. im gonna build a few boxes just for one sub to experiment with. hopefully within the next couple of weeks. I want to build like 6 different boxes 3 with the same volume and tuning but diff port area and 3 with the same port area and tuning but different volumes.

gonna have some cheap 12" boxes for sale soon hahah.

Is it possible that the shape of the box is causing issues? (like the fact its really long and the sub fires into the length)

ciaonzo
11-27-2009, 05:38 PM
ok to clarify all the problems i have 2 seperate boxes which i run BOTH at the same time usually. the specs given are for one box. so multiply by 2 and there ya go.

My amp is used for both subs. wired down to .5 ohm. (1 ohm when im using 1 sub) problem still happens either using 1 or 2 subs.

voltage drop is not a problem i dip into the mid 12's at the lowest. got a 200 amp alt 2 spv70's and a stock batt. only 1 run of 1/0 tho for pos and ground. but as stated before my voltage drop isint that bad.

all my filter and eq settings are set correctly. flat on the eq. filter on the hu is set at 80hz, filter on the amp is probably at 70. If i cross down to 50 i will have no output between 50-80 hz, my momo components are nowhere near as loud as my aplhas. and dont really start hitting until about 80-100hz. (I need speaker pods my doors **** for sealing)

My speaker wire is 10 gauge and i have separate runs for each woofer directly from the amp. the wire shown was just for testing.

Imp rise might be a very likely cause but how do i get around this. never had this problem before. and ive built tons of boxes and systems. non having this large of port area though. but thor and all those other guys with big ports dont have this problem either so idk.

Lots of good input in this thread, particularly in posts #17 and #19, so I won't reiterate anything there. One concern of mine is that you're using two low pass filters. This can work but it takes some planning. If you cascade two filters you can get good results and you can get very bad results, all depends on the application and the execution. If you use two steep filters right on top of each other you will get a peak right around the filter pole in the pass band. Couple that with a high inductance figure for your driver and you can get quite a nasty peak. I can't say for sure if that's what you've got going on but it's a possibility. Try using one low pass at 24dB instead of two at whatever they are now. That's not accounting for anything that anyone else has already pointed out.

ciaonzo
11-27-2009, 06:00 PM
Shot you a PM as well.

SSS 18734
11-27-2009, 06:23 PM
The problem is most likely with your enclosure. Your box design should reflect the excursion and power handling abilities of your sub.

Download WinISD Alpha (not beta) and correctly enter the parameters of your sub. There is a tab that allows you to see the excursion of the sub at any given frequency with any given amount of power. Adjust your box design according to that and build a new one.

Remember, cabin gain exaggerates low frequencies. You could be expecting too much of your sub at higher ones. At a tuning of 37, you're going to have a huge peak around those two lower frequencies.

mendon mafia
11-27-2009, 06:43 PM
The problem is most likely with your enclosure. Your box design should reflect the excursion and power handling abilities of your sub.

Download WinISD Alpha (not beta) and correctly enter the parameters of your sub. There is a tab that allows you to see the excursion of the sub at any given frequency with any given amount of power. Adjust your box design according to that and build a new one.

Remember, cabin gain exaggerates low frequencies. You could be expecting too much of your sub at higher ones. At a tuning of 37, you're going to have a huge peak around those two lower frequencies.

i used to have a pair of 12" re sx's and i ran them in 5 cubes net tuned to 32 hz and never had a problem. The port was small though only 58" and it was straight not L shaped

dappa5
11-27-2009, 07:47 PM
.02 here port to big the reason it looks the same when you free air it is because you are loosing cone control /"unloading" / over those freqs gl with new boxes

mendon mafia
11-27-2009, 09:06 PM
.02 here port to big the reason it looks the same when you free air it is because you are loosing cone control /"unloading" / over those freqs gl with new boxes

it actually looks completely different when i free air it.

the cone moves MORE on the higher note (hypnotize young jeezy) IN THE BOX than in free air. How could the cone be more controlled in free air than in the box?

the low notes both move less in the box but the same ratio to each other the lower on moves less in both cases.

mlstrass
11-28-2009, 01:07 AM
PM DDbump as he had a similar problem with his HW's for a while. Don't remember what we did to get it resolved...

mendon mafia
11-28-2009, 09:47 PM
PM DDbump as he had a similar problem with his HW's for a while. Don't remember what we did to get it resolved...

So DDbump got back to me and he said he had this problem with his HW's and alpha's.

He said he thought it was the suspension :confused:

gonna experiment more when i find time. I love the lows on these subs to much to swap out at the moment. below 40hz is just awesomeness to my ears.

SSS 18734
11-28-2009, 09:57 PM
Another issue that I didn't pay attention to before was your port. The end of that port is awfully close to the corner of the enclosure - Your sub is seeing a port that is about 5-6 inches longer than you intended it to be (unless you intended the design to be that way).

In either case, you should try dropping the port area a bit. 25-35 square inches should be more than adequate. This will also allow the end of the port to be further away from the side of the box.

I suppose it could be an issue with the sub itself, but there are a lot of other variables here that could easily be the solution.

photocrazy8
11-28-2009, 09:59 PM
box looks way off, you need to redesign it...

mmouse57
11-29-2009, 12:16 AM
massive port man you could have done 2x12 and got the same results with port noise

mendon mafia
11-29-2009, 09:14 AM
massive port man you could have done 2x12 and got the same results with port noise

yes but with less spl.

PV Audio
11-29-2009, 12:26 PM
Post up the T/S for the speaker. It might be that with your given enclosure size, your system Q increases significantly at higher frequencies thus causing the sub to become undamped in its box. I've had it happen before when using high Qts cones in ported boxes.

mendon mafia
11-29-2009, 02:08 PM
Name= Alpha12d2
Note= paper cone.mag180c25x2
Model= TSL
Domain= FreeAir
Shape= Round
Profile= Cone
Fmd= 3.0000 KA
Qmd= 1.0000
Flp= 8.0000 KA
Qlp= 2.0000
Znom= 1.8000 Ohm
Revc= 3.6000 Ohm
Sd= 55.0000E-3 M
Mmd= 198.0000E-3 Kg
Pmax= 2.0000E3 W
Rtvc= 125.0000E-3 C/W
Xgap= 20.0000 M
Xcoil= 54.0000 M
Xmax= 17.0000 M
Krm= 11.5600E-3 Ohm
Erm= 858.0000E-3
Kxm= 136.0000E-3 H
Exm= 560.0000E-3
Rms= 9.2457 NS/M
Mms= 205.4126E-3 Kg
Cms= 121.1818E-6 M/N
Vas= 52.3579E-3 M
Fs= 31.5998 Hz
Qms= 4.4530
Qes= 0.3506
Qts= 0.3250
BL= 20.5610 TM
Levc= 2.8996E-3 H
SPLo= 88.8905 dB
No= 464.7595E-3 %


LOL just realized its a sticky on caco.

mendon mafia
11-29-2009, 04:51 PM
The problem is most likely with your enclosure. Your box design should reflect the excursion and power handling abilities of your sub.

Download WinISD Alpha (not beta) and correctly enter the parameters of your sub. There is a tab that allows you to see the excursion of the sub at any given frequency with any given amount of power. Adjust your box design according to that and build a new one.

Remember, cabin gain exaggerates low frequencies. You could be expecting too much of your sub at higher ones. At a tuning of 37, you're going to have a huge peak around those two lower frequencies.

downloaded the program and if i tune to 44hz is the only way i dont over extend the sub past x max above tuning. port area for some reason has no effect.

Lakota
11-29-2009, 07:41 PM
Box programs, meh. Everything changes once the box is put into a vehicle.

The box may be very peaky, causing it to have trouble controlling the sub if you're playing out of its optimum bandwidth.

mendon mafia
11-29-2009, 09:52 PM
Box programs, meh. Everything changes once the box is put into a vehicle.

The box may be very peaky, causing it to have trouble controlling the sub if you're playing out of its optimum bandwidth.

i was just saying the box program is confirming what is happening in my enclosure. but according to the program all boxes tuned to 38hz should have the same problem.

zierbox
11-30-2009, 12:59 PM
I agree with the option of; way to much port

The sub is not seeing the box (the air is simply rushing out the port)
You have to make up your mind, do you want an SPL box that plays limited frequencies loud or a box that play a wide range of music loud and in control

With that much air space I would also lower the tuning frequency

mendon mafia
11-30-2009, 02:06 PM
I agree with the option of; way to much port

The sub is not seeing the box (the air is simply rushing out the port)
You have to make up your mind, do you want an SPL box that plays limited frequencies loud or a box that play a wide range of music loud and in control

With that much air space I would also lower the tuning frequency

im going to modify the boxes i have my cutting out the bend so that the port open up into the other corner. If that sounds ****** ill re build wither using 32" of area or a 6" aero port.

Most likely going to build a few different boxes of different sizes since i doubt my modification will work but i need a 30" long port if i use a 6" aero so it probably wont happen due to cost.

patotay
11-30-2009, 02:21 PM
not a pro..try cutting some port.nice amp

mendon mafia
12-01-2009, 07:48 PM
gonna add 45;s since it will only take a sec to do. is it even worth trying?

PV Audio
12-02-2009, 12:07 AM
gonna add 45;s since it will only take a sec to do. is it even worth trying?If it's a port issue, it's because the box is acting like a truncated transmission line. Basically what's happening is that instead of acting like a resonator which a ported box does, it's acting as a phase inverter like a transmission line. Problem is that the line isn't long enough to have the backwave shift phase by 180 degrees, and all you're getting is terrible mechanical damping.

mendon mafia
12-02-2009, 01:15 AM
If it's a port issue, it's because the box is acting like a truncated transmission line. Basically what's happening is that instead of acting like a resonator which a ported box does, it's acting as a phase inverter like a transmission line. Problem is that the line isn't long enough to have the backwave shift phase by 180 degrees, and all you're getting is terrible mechanical damping.

yea that sounds exactly like my problem. because it sounds like its canceling out or somthing. that would explain why it moves move in the box than out if it. Dont transmission lines require the same port area as cone area though?

PV Audio
12-02-2009, 01:48 AM
yea that sounds exactly like my problem. because it sounds like its canceling out or somthing. that would explain why it moves move in the box than out if it. Dont transmission lines require the same port area as cone area though?Yes, but your box isn't acting like a true transmission line. By not giving the speaker airspace to pressurize, all that's happening is that you're shooting the air down a tube. A transmission line does the same thing, except it actually exits the tube as something useful.

mendon mafia
12-02-2009, 11:19 PM
so should i not waste the time with 45's then?

I was also gonna try cutting port wall back a bit to raise tuning but also to get the port opening farther from the corner, or is this not worth doing either.

If none of that helps i was going to completely remove the port bend piece and then line the inner port wall until it reduces the port area to a point where its better. cutting back the port length if necessary.

if this all sounds like a waste of time please let me know as i dont have much time to do my builds but i want to be sure i get good results this time as i paid a lot for these woofers.

might sound difficult but im very good with a demo saw :) at this point im just experimenting so i dont waste any more wood lol. ill build new boxes after i find a suitable port area.

probably do a common chamber next time and do ported on the driver side. or 2 6" aeros in the middle with 90bends.

Joseph M
12-02-2009, 11:24 PM
uhm... tell you now sucess take expirements no matter what anyone tells you

sub-FATHER
12-03-2009, 12:23 AM
its called CLIPPING YOUR CLIPPING THE SIGNAL, CLIPPING CAUSES THE SUBS TO MOVE FROM ONE END TO THE OTHER ON CERTAIN FREQUENCIES.

WHEN I GO FROM 2 AMPS TO JUST ONE AMP, MY 18S DO THIS. BUT WITH BOTH AMPS THE SUBS STAY IN CONTROL.

mendon mafia
12-03-2009, 12:49 AM
its called CLIPPING YOUR CLIPPING THE SIGNAL, CLIPPING CAUSES THE SUBS TO MOVE FROM ONE END TO THE OTHER ON CERTAIN FREQUENCIES.

WHEN I GO FROM 2 AMPS TO JUST ONE AMP, MY 18S DO THIS. BUT WITH BOTH AMPS THE SUBS STAY IN CONTROL.

In case you did not watch the vid i posted...

if i was running my amp to the point of clipping i would be hitting that single 12" alpha with 3k+. its wired up to 1 ohm in the vid. also in the vid i am only running on my stock 600cca battery and 200 amp alt and the voltage isint even dropping below 13.

clearly 3k rms on a stock batt and 200 amp alt would pull my voltage way down easily to the 12's if not 11's or 10's. I used to do it all the time with my 2k amp.

all that aside, your clipping

PV Audio
12-03-2009, 01:31 AM
its called CLIPPING YOUR CLIPPING THE SIGNAL, CLIPPING CAUSES THE SUBS TO MOVE FROM ONE END TO THE OTHER ON CERTAIN FREQUENCIES.

WHEN I GO FROM 2 AMPS TO JUST ONE AMP, MY 18S DO THIS. BUT WITH BOTH AMPS THE SUBS STAY IN CONTROL.


In case you did not watch the vid i posted...

if i was running my amp to the point of clipping i would be hitting that single 12" alpha with 3k+. its wired up to 1 ohm in the vid. also in the vid i am only running on my stock 600cca battery and 200 amp alt and the voltage isint even dropping below 13.

clearly 3k rms on a stock batt and 200 amp alt would pull my voltage way down easily to the 12's if not 11's or 10's. I used to do it all the time with my 2k amp.

all that aside, your clipping
Do not even pay him any mind, sub2weeker has proven many many times that he does not know anything at all. This problem has absolutely nothing to do with clipping in the slightest.

patotay
12-03-2009, 01:21 PM
that one's funny..lol

"the port opening farther from the corner"..this sounds good!
there's no excess air for the sub to ****.i may be wrong

mendon mafia
12-03-2009, 04:44 PM
that one's funny..lol

"the port opening farther from the corner"..this sounds good!
there's no excess air for the sub to ****.i may be wrong

you do know what i mean correct?

someone mentioned it was close to the corner. it is, its about 5-6" away from the opposite wall, for a 4" port that is pretty close.

im gonna cut it back about 3" to start (after determining the effect of 45's), should raise tuning into the low 40's as well maybe it will control the cone better in the higher range after.

SicAudio
12-03-2009, 05:06 PM
maybe the box length is causing backwaves? i would definately listen to PV he is about as sharp as they come IMO. but like another said you need to decide if you want music or a fart box.

GAM3OVR
12-03-2009, 05:25 PM
Didnt want to read all the posts, but the Box port looks way more then the box needs, and you net box volume came out to be like 1.93 and tuning close to 39.


I would go back and build a box w/ 2.2 net w/ 34sq in of port area tuned to 35 and see if that gets you a better result. Hopefully the sub unloads better

mendon mafia
12-03-2009, 05:48 PM
Didnt want to read all the posts, but the Box port looks way more then the box needs, and you net box volume came out to be like 1.93 and tuning close to 39.


I would go back and build a box w/ 2.2 net w/ 34sq in of port area tuned to 35 and see if that gets you a better result. Hopefully the sub unloads better

what calculator did you use? i used the one on 12 volt but apparently it way off. what did you figure for sub displacement? I was figuring .22 for a 12"

PV Audio
12-03-2009, 09:32 PM
maybe the box length is causing backwaves? i would definately listen to PV he is about as sharp as they come IMO. but like another said you need to decide if you want music or a fart box.:laugh: I wouldn't put that much faith in me. There are people here like ciaonzo and JimJ who know more about audio than I could hope to.

SicAudio
12-03-2009, 09:39 PM
.22 for 1 sub? closer to .10 if that

mendon mafia
12-03-2009, 09:58 PM
.22 for 1 sub? closer to .10 if that

1.93 cubes is wrong then.

i get 2.2 cubes before driver displacement for EACH BOX that i built

Boxes are .75" thick mdf. 31" long, 18.5 wide, 13.5 tall. port is 4" wide 12" tall.

the port opening inside the box (bent part) is 5" away from the inside wall.

leaves me with 24x12.25 area for the big section. plus the opening for the port which is 5x4.75 so thats 24x12.25 + 5x4.75 = 317.75 x 12 = 3813 /(12^3) = 2.206 cubes before sub displacement.

How do you get 1.93?

SicAudio
12-03-2009, 10:09 PM
i never calculated the box someone else di i said .22 for 1 sub is wrong closer to .10 if that unless its got a huge motor like a nightshade ect.

SicAudio
12-03-2009, 10:14 PM
:laugh: I wouldn't put that much faith in me. There are people here like ciaonzo and JimJ who know more about audio than I could hope to.

i said aboutas sharp not the sharpest lolz yeah i have some of their posts and they know sum **** too lolz several on here actually do and they share it alot vs flaming people lolz. all good qualities imo.

mendon mafia
12-03-2009, 10:18 PM
i never calculated the box someone else di i said .22 for 1 sub is wrong closer to .10 if that unless its got a huge motor like a nightshade ect.

no you didnt calculate it but 2 others did and they both got 1.93 i must be doing somthing wrong i guess.

ciaonzo
12-03-2009, 10:25 PM
:laugh: I wouldn't put that much faith in me. There are people here like ciaonzo and JimJ who know more about audio than I could hope to.

You're too kind, but thanks. I'm not that smart. Besides, you're the one who'll be an EE soon. I'm just drawing from years of experience which means I did it the hard way. :crap:

Redlineaudio
12-03-2009, 10:45 PM
Lots of good input in this thread, particularly in posts #17 and #19, so I won't reiterate anything there. One concern of mine is that you're using two low pass filters. This can work but it takes some planning. If you cascade two filters you can get good results and you can get very bad results, all depends on the application and the execution. If you use two steep filters right on top of each other you will get a peak right around the filter pole in the pass band. Couple that with a high inductance figure for your driver and you can get quite a nasty peak. I can't say for sure if that's what you've got going on but it's a possibility. Try using one low pass at 24dB instead of two at whatever they are now. That's not accounting for anything that anyone else has already pointed out.



Go back to this post and start there. I did not see in the posts where you had changed this. Filters have a peak before they roll off, two peaks could be causing the problem.



Next I would change the sub location. from the end to the side. cut a new hole and just put a board over the end. See if that helps.



Also I am not a pro but I did stay at a holiday inn express last night.

ciaonzo
12-03-2009, 10:56 PM
Go back to this post and start there. I did not see in the posts where you had changed this. Filters have a peak before they roll off, two peaks could be causing the problem.



Next I would change the sub location. from the end to the side. cut a new hole and just put a board over the end. See if that helps.



Also I am not a pro but I did stay at a holiday inn express last night.

Haha, caught me off guard with that one. I was bustin' a gut. :laugh:

mbrooky
12-03-2009, 11:17 PM
ever thought of trying to cap the the hole and mounting the sub on the side or top so it has something to load off of instead of just straight into the port...might help some...or just build another...

edit: just noticed that redline suggested it as well..:p:

mendon mafia
12-03-2009, 11:50 PM
Go back to this post and start there. I did not see in the posts where you had changed this. Filters have a peak before they roll off, two peaks could be causing the problem.



Next I would change the sub location. from the end to the side. cut a new hole and just put a board over the end. See if that helps.



Also I am not a pro but I did stay at a holiday inn express last night.

hahahaha good one.

i already have tried using one or the other or neither and either way same problem.

i will try sub location i guess ill try that after trying a 45 since its easier.

mbrooky
12-04-2009, 12:21 AM
i wouldn't waste my time on 45s...don't see how that would change anything...change sub location...

another guy had the same problem...this did not work:
http://i16.photobucket.com/albums/b19/burzendowski/truck52.jpg

but this did:
http://i16.photobucket.com/albums/b19/burzendowski/05.png

and what's funny is he could've just capped the first enclosure and relocated the sub above the port...but instead spent more money on basically the same enclosure with the sub in the right location :p:

mendon mafia
12-04-2009, 12:42 AM
in my case i needed to design the way i did because there was 2 of those same enclosures side by side firing into the cabin of my sedan through the trunk ports in the middle.

mbrooky
12-04-2009, 02:42 AM
ah i see....well scrap it then and do a new build :p:

this should work for ya:
3cuft@34Hz 43.75 sqin port 32x20x14

PV Audio
12-04-2009, 03:01 AM
i wouldn't waste my time on 45s...don't see how that would change anything...change sub location...

another guy had the same problem...this did not work:
http://i16.photobucket.com/albums/b19/burzendowski/truck52.jpg

but this did:
http://i16.photobucket.com/albums/b19/burzendowski/05.png

and what's funny is he could've just capped the first enclosure and relocated the sub above the port...but instead spent more money on basically the same enclosure with the sub in the right location :p:And probably paid 60 bucks for the PWK design too, eh?

ciaonzo
12-04-2009, 03:28 AM
I modeled for both "flat" and output-oriented but mbrooky beat me to the punch for the output numbers. His results matched mine nearly perfectly so I just modeled what he posted instead and created an overlay plot so you can compare the two. The bluish color is the "flat" model and will cater to a better balance for music purposes. The magenta color is the output model will provide more impact and will suit hip-hop nicely. It will have a higher group delay but nothing grotesque. I come from the school of anything higher than 10milliseconds above 40Hz is undesirable so this one just sneaks in there. Both are good models and it will come down to personal taste. Somewhat flat in-car response is achieved with 2cu.ft. @30Hz, 31.5sq.in. of vent area (I modeled with 14 x 2.25) with 43.25" of length. A minimal amount of lining on the walls but do not inhibit airflow for the vent. I did not bother with a drawing because I assume you know how to figure for volume and displacements. I rarely bother with a drawing, truthfully.

The six graphs illustrate the following;

Upper left - normalized frequency response (generic in-car transfer function applied)

Upper right - group delay

Middle left - vent velocity with 2000 watts of power input (both are great)

Middle right - acoustic power, this helps you visualize the thermal and mechanical limits.

Lower left - excursion with 2000 watts of power input

Lower right - impedance curve




http://i704.photobucket.com/albums/ww43/ciaonzo/Temp/mendon.jpg

PV Audio
12-04-2009, 03:38 AM
Whoa, post up the phase plot for that. Your group delay plot is beautifully smooth :drool:

ciaonzo
12-04-2009, 03:42 AM
Whoa, post up the phase plot for that. Your group delay plot is beautifully smooth :drool:

Actually, that's about as ugly as mine get. Not my kind of driver truthfully, no offense OP. You should see the group delay plots on my esoteric approaches.

Gimme a minute to model that one again so I can get you the phase plot. I'll model it with and without the inductance so you can see the impact it has on phase magnitude.

ciaonzo
12-04-2009, 03:53 AM
This is my "flat" model from above (bluish plot)with another plot which excludes the inductance spec (magenta). Note how it peaks in the pass band and how it affects the minimum phase (middle left graph).

http://i704.photobucket.com/albums/ww43/ciaonzo/Temp/PVphase.jpg

SicAudio
12-04-2009, 04:06 AM
great job Ciaonzo i did the same thingwith his orignal box and that sub plots horible in the box he had. how did you copy the screen shot in bpp? i use it as well and never figured it out lolz.

ciaonzo
12-04-2009, 04:12 AM
great job Ciaonzo i did the same thingwith his orignal box and that sub plots horible in the box he had. how did you copy the screen shot in bpp? i use it as well and never figured it out lolz.

Thanks. Indeed, the original does plot quite horribly, lol. Again, no offense mendon. :p:

Once you have everything in order, just hit "Print Screen". Next, open up Paint and paste it. Then "save as" whatever. :)

SicAudio
12-04-2009, 04:19 AM
ok sweet thanks i cant believe i never thought of that lolz
gl with the new build mendon.

ciaonzo
12-04-2009, 04:21 AM
Whoa, post up the phase plot for that. Your group delay plot is beautifully smooth :drool:

Here you go, PV. One of the best group delay plots one could hope for regarding a vented enclosure. Not a very conventional design with about the same excursion as a sealed enclosure, except for right at tuning, but extremely well behaved overall. This is the driver that I had you double check the math for, concerning the parameter extrapolation. It doesn't get very loud but it has bandwidth. :)

http://i704.photobucket.com/albums/ww43/ciaonzo/Temp/PV4000.jpg

Edit* I forgot to mention that this is for two-channel music at home, no generic vehicle transfer function applied.

ciaonzo
12-04-2009, 04:23 AM
ok sweet thanks i cant believe i never thought of that lolz
gl with the new build mendon.

You bet.



x2 mendon, good luck.

mendon mafia
12-04-2009, 12:54 PM
Hey guys thanks a lot for all the help gonna build new enclosures soon.

ciaonzo, is that 2 cubes net for BOTH drivers, aka 1 cube each? that seems way to small imo. granted its for flattest response, thats half what they are seeing now lol.

also when it says at 2000 watts of power is that for each sub? I have my atomic at .5 ohm so it will be about 1600 each sub at full tilt (obv less after rise)

ciaonzo
12-04-2009, 02:37 PM
Hey guys thanks a lot for all the help gonna build new enclosures soon.

ciaonzo, is that 2 cubes net for BOTH drivers, aka 1 cube each? that seems way to small imo. granted its for flattest response, thats half what they are seeing now lol.

also when it says at 2000 watts of power is that for each sub? I have my atomic at .5 ohm so it will be about 1600 each sub at full tilt (obv less after rise)

Yes, that is the system response. Both drivers in 2cu.ft. net with 2000 watts applied will yield those results. It seems small because lots of guys who are just going for numbers build large enclosures to keep vent dimensions manageable (short) but they do that without regard for optimal performance in other areas such as peaky frequency response and a lowered mechanical power handling at frequencies not supported by the vent, which is what you experienced. Other enclosures that are designed properly and are still large, are most likely the result of a driver that has a large Vas. The BL product for your driver is pretty high and the Vas is pretty low, as is the Qts. That all adds up to a small enclosure (and a long vent for low tuning, PR's rule!). Your enclosure will still be sizable due to the fact that you'll need to factor in the displacement of the vent (.79cu.ft.). You can safely throw 3200 at this system (flat) without much concern for over-excursion until you get down to around 25Hz. Be sure to use your SSF if you intend abuse them.

mbrooky
12-04-2009, 02:42 PM
And probably paid 60 bucks for the PWK design too, eh?
haha..yea...and claimed he spent $130 on the first enclosure:wow: sorry but i would've capped the first one and relocated the sub...if any depth issues the double baffle from capping it should suffice or throw a ring on there for clearance..cheap solution...not 60 more for a design..lol




I modeled for both "flat" and output-oriented but mbrooky beat me to the punch for the output numbers. His results matched mine nearly perfectly so I just modeled what he posted instead and created an overlay plot so you can compare the two. The bluish color is the "flat" model and will cater to a better balance for music purposes. The magenta color is the output model will provide more impact and will suit hip-hop nicely. It will have a higher group delay but nothing grotesque. I come from the school of anything higher than 10milliseconds above 40Hz is undesirable so this one just sneaks in there. Both are good models and it will come down to personal taste. Somewhat flat in-car response is achieved with 2cu.ft. @30Hz, 31.5sq.in. of vent area (I modeled with 14 x 2.25) with 43.25" of length. A minimal amount of lining on the walls but do not inhibit airflow for the vent. I did not bother with a drawing because I assume you know how to figure for volume and displacements. I rarely bother with a drawing, truthfully.

The six graphs illustrate the following;

Upper left - normalized frequency response (generic in-car transfer function applied)

Upper right - group delay

Middle left - vent velocity with 2000 watts of power input (both are great)

Middle right - acoustic power, this helps you visualize the thermal and mechanical limits.

Lower left - excursion with 2000 watts of power input

Lower right - impedance curve




http://i704.photobucket.com/albums/ww43/ciaonzo/Temp/mendon.jpg

Sweet!:D

mendon mafia
12-04-2009, 05:25 PM
Yes, that is the system response. Both drivers in 2cu.ft. net with 2000 watts applied will yield those results. It seems small because lots of guys who are just going for numbers build large enclosures to keep vent dimensions manageable (short) but they do that without regard for optimal performance in other areas such as peaky frequency response and a lowered mechanical power handling at frequencies not supported by the vent, which is what you experienced. Other enclosures that are designed properly and are still large, are most likely the result of a driver that has a large Vas. The BL product for your driver is pretty high and the Vas is pretty low, as is the Qts. That all adds up to a small enclosure (and a long vent for low tuning, PR's rule!). Your enclosure will still be sizable due to the fact that you'll need to factor in the displacement of the vent (.79cu.ft.). You can safely throw 3200 at this system (flat) without much concern for over-excursion until you get down to around 25Hz. Be sure to use your SSF if you intend abuse them.


Yea a PR may be a good investment i can have a full trunk still lol. What size would be good for 2 12's

BTW could i simply cut the dimensions in half and have a suitable box for one 12" or are the box sizes specific to both drivers and need to do different calculations for a single sub?

Ok so im going to build a box for my 15" btl as well over my break. i was thinking 4 cubes net 70" port area tuned to 35 hz. Ive heard btls love big ports and big boxes. is this true? Whats do you recommend?

ciaonzo
12-04-2009, 05:37 PM
Yea a PR may be a good investment i can have a full trunk still lol. What size would be good for 2 12's

BTW could i simply cut the dimensions in half and have a suitable box for one 12" or are the box sizes specific to both drivers and need to do different calculations for a single sub?

Ok so im going to build a box for my 15" btl as well over my break. i was thinking 4 cubes net 70" port area tuned to 35 hz. Ive heard btls love big ports and big boxes. is this true? Whats do you recommend?

Nope, you can't just cut the volume in half for this particular situation. I mean, you can, but you won't get the same smooth response and you'll have an even longer vent. Two drivers sharing a common volume with a single vent is optimal. If small size becomes a priority, I would certainly go with a PR setup or a sealed enclosure. I can't recommend a specific PR alignment unless I know the Vap, Cms, and Sd of the PR you use. Generally, the lower you tune, the more PR you need. If you were to go sealed, I would get a driver that will work better in that scenario. That's just me though.

I don't have any experience with fi so you might want to consult with someone else on that topic.

mendon mafia
12-04-2009, 08:06 PM
Nope, you can't just cut the volume in half for this particular situation. I mean, you can, but you won't get the same smooth response and you'll have an even longer vent. Two drivers sharing a common volume with a single vent is optimal. If small size becomes a priority, I would certainly go with a PR setup or a sealed enclosure. I can't recommend a specific PR alignment unless I know the Vap, Cms, and Sd of the PR you use. Generally, the lower you tune, the more PR you need. If you were to go sealed, I would get a driver that will work better in that scenario. That's just me though.

I don't have any experience with fi so you might want to consult with someone else on that topic.

So what steps would i take to build a box for just one subwoofer? Im guessing that most people simply dont care how there bass sounds cuz nobody seems to take this much effort in designing boxes.

Space is not really a concern just would be nice to have a full trunk and a 145+ db setup. I got 13 cubes to play with but I can only fit a 6 cube box without building in the vehicle. There is only 14" height opening into my cabin too so i cant fire 15's directly into the cabin without tilting them and my btl cant tilt enough cuz the motor is to wide and it hits the floor of the box. other wise id be running the btl and enver would have bought the alphas.

ciaonzo
12-04-2009, 08:21 PM
So what steps would i take to build a box for just one subwoofer? Im guessing that most people simply dont care how there bass sounds cuz nobody seems to take this much effort in designing boxes.

Space is not really a concern just would be nice to have a full trunk and a 145+ db setup. I got 13 cubes to play with but I can only fit a 6 cube box without building in the vehicle. There is only 14" height opening into my cabin too so i cant fire 15's directly into the cabin without tilting them and my btl cant tilt enough cuz the motor is to wide and it hits the floor of the box. other wise id be running the btl and enver would have bought the alphas.

Yep, lots of guys are simply going for output so they use as much vent area as they can and to keep the vent length down they go with more volume than is needed. Might be loud, but it's certainly not accurate and it probably exhibits poor cone damping and a hollow sounding character. Everyone's mileage will vary and there are some clever solutions that go against the usual logic so I'm not addressing those individuals who know exactly what they're doing with regards to very specific custom installs. I'm describing those individuals who tend to "design" and build enclosures to have a certain tuning and then attempt stick any old driver in there and can't understand why something just isn't right.

I should clarify that it won't always be the case where you have to have two subs in the same air space but when using subs with a low Vas, it's very effective.

I just wanted to help you with your initial problem and hopefully to give a bit of insight as to how certain things can affect certain results. I'll be the first to say that I do not care for SPL setups and I do not specialize in them so you may want to seek the help of someone like mobeious or many others who are well versed in SPL designs. :)

SicAudio
12-04-2009, 08:31 PM
Ciaonzo is dropping knowledge all over the place folks so take notes!

mendon mafia
12-04-2009, 08:57 PM
Yep, lots of guys are simply going for output so they use as much vent area as they can and to keep the vent length down they go with more volume than is needed. Might be loud, but it's certainly not accurate and it probably exhibits poor cone damping and a hollow sounding character. Everyone's mileage will vary and there are some clever solutions that go against the usual logic so I'm not addressing those individuals who know exactly what they're doing with regards to very specific custom installs. I'm describing those individuals who tend to "design" and build enclosures to have a certain tuning and then attempt stick any old driver in there and can't understand why something just isn't right.

I should clarify that it won't always be the case where you have to have two subs in the same air space but when using subs with a low Vas, it's very effective.

I just wanted to help you with your initial problem and hopefully to give a bit of insight as to how certain things can affect certain results. I'll be the first to say that I do not care for SPL setups and I do not specialize in them so you may want to seek the help of someone like mobeious or many others who are well versed in SPL designs. :)

Having said what you did above im guessing i can kiss my 145's good bye?

Are there any extreme dimensions i should stay away from. Like aspect ratio or somthing like that? I speced out a box on the re calc (i know its way off) box width: 36", box height: 13.5", box depth 14.5, with a 2.75" wide port and a square port length 2 of 24". On the re site it specs out to 2.338 cubes @ 29.18hz Does this look good for the flat response?

EDIT: this does not account for double baffle, i will make adjustments just want to see if the basic layout and volume and tuning looks good.

Its quite odd that steve miller recommended me to build 2 cubes net for each sub. you would think he should know the driver really preforms in a smaller enclosure, he also told me to use half the port area but i ignored him lol.

Im still going to experiment with my enclosure for a single 12 just to see what i like the best. i may build the box calculated for flattest response and build a second based off of my experimentation. I have some time coming up and mdf is relatively cheap in the ca world so i think i want to learn and see some things first hard.

Ill start a thread in about a week when i start building. ill post it in the build log section i guess.

ciaonzo
12-04-2009, 09:23 PM
Having said what you did above im guessing i can kiss my 145's good bye?

Are there any extreme dimensions i should stay away from. Like aspect ratio or somthing like that? I speced out a box on the re calc (i know its way off) box width: 36", box height: 13.5", box depth 14.5, with a 2.75" wide port and a square port length 2 of 24". On the re site it specs out to 2.338 cubes @ 29.18hz Does this look good for the flat response?

EDIT: this does not account for double baffle, i will make adjustments just want to see if the basic layout and volume and tuning looks good.

Its quite odd that steve miller recommended me to build 2 cubes net for each sub. you would think he should know the driver really preforms in a smaller enclosure, he also told me to use half the port area but i ignored him lol.

Im still going to experiment with my enclosure for a single 12 just to see what i like the best. i may build the box calculated for flattest response and build a second based off of my experimentation. I have some time coming up and mdf is relatively cheap in the ca world so i think i want to learn and see some things first hard.

Ill start a thread in about a week when i start building. ill post it in the build log section i guess.

No, I would never let go of your aspirations of getting over 145, it's certainly possible. I would just go with someone else's guidance to achieve that.

Based on the type of driver it is and the market niche it was intended for, I'm sure Steve told you to use the Alpha in 2 cubes to get you the most output for your dollar.

Regarding extreme dimensions for enclosures, it's like this. Long dimensions set up standing waves and if you build a tall, slim tower speaker you can end up with a standing wave for the half wavelength on the longest measurement. That will also have a large impact on the fundamental frequency response according to the quarter wavelength dimension and the 3rd, 5th, 7th, and 9th harmonics of that fundamental. The short answer is that for subwoofer applications, you won't have to worry about it because you're not likely to encounter any lengths long enough to have any impact on the frequencies within the pass band for the system. Build whatever size and shape you want.

I think it's great that you intend to build a number of different enclosures because as the old cliche goes, there's no teacher like experience.

cww180
12-04-2009, 09:41 PM
Can anyone with that program help me with a box design? I would love to know the box is going to be accurate before the build.

S.B.C.
12-04-2009, 09:43 PM
wall it

thnx

GAM3OVR
12-04-2009, 11:42 PM
what calculator did you use? i used the one on 12 volt but apparently it way off. what did you figure for sub displacement? I was figuring .22 for a 12"

I use pencilandpaper.do application

you should try it sometime

mendon mafia
12-05-2009, 01:22 PM
I use pencilandpaper.do application

you should try it sometime

So your bad at math then? how on earth did you get 1.93?

I get 2.04 without the little nook in the corner near the port with the nook in the corner i get and extra .165 totalling 2.205 cubes net before driver displacement. Subtract .2(.1) for sub displacement and perfect 2(2.1) cubes net.

I use pencil and paper before i build any enclosure. I just use the re calcs and others to get close before i draw. they predict volume perfectly every time you just gotta figure the sub displacement on your own since it doesn't account for that. And port length i use the 12volt

is there a better calc out there i should use for port length? im not sure how to calculate port length by pencil and paper. This is like the 10th enclosure ive built and the only one ive had a problem with so i doubt its the calc anyways rather than just my massive port area.

It doesn't matter cuz 2 cubes is not the right size anyways and the box size is less of a problem than my port size probably

GAM3OVR
12-05-2009, 08:23 PM
with the exact sub displacement and not counting the corner of the port where it end(port entry)

1.93 something is what I got.

mbrooky
12-06-2009, 11:52 AM
bigger pic...build it!:p:

http://img80.imageshack.us/img80/9668/3cu34hz4375sqinport32x2.th.png (http://img80.imageshack.us/i/3cu34hz4375sqinport32x2.png/)

mendon mafia
12-06-2009, 02:27 PM
with the exact sub displacement and not counting the corner of the port where it end(port entry)

1.93 something is what I got.

so your just ignoring that corner? you gotta either count it as port length or box volume. But yea i see the 1.93 now but its still wrong.


bigger pic...build it!:p:

http://img80.imageshack.us/img80/9668/3cu34hz4375sqinport32x2.th.png (http://img80.imageshack.us/i/3cu34hz4375sqinport32x2.png/)

Im going to build it slightly different. 36 wide, 19 deep, 13.5 tall. port area is 48" tunes to ~34 hz. This will seal to the cabin of my car better than 32" wide. I only need a small foam gasket to seal it off if its 36 wide.

I want to try to do a kerfed port opening as well as for the port bend. You only count the opening as half the length right? ie. if the port flare is a 4" radius only 2" will count to port length?

Heres a pics. Notice that the blue port length line dosnt go all the way to the ends of the port openings.

http://i837.photobucket.com/albums/zz297/Mendonmafia/Kerfedbox.jpg

mendon mafia
12-06-2009, 11:11 PM
so your just ignoring that corner? you gotta either count it as port length or box volume. But yea i see the 1.93 now but its still wrong.



Im going to build it slightly different. 36 wide, 19 deep, 13.5 tall. port area is 48" tunes to ~34 hz. This will seal to the cabin of my car better than 32" wide. I only need a small foam gasket to seal it off if its 36 wide.

I want to try to do a kerfed port opening as well as for the port bend. You only count the opening as half the length right? ie. if the port flare is a 4" radius only 2" will count to port length?

Heres a pics. Notice that the blue port length line dosnt go all the way to the ends of the port openings.

http://i837.photobucket.com/albums/zz297/Mendonmafia/Kerfedbox.jpg

No help here?