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View Full Version : Plans for an SPL Box, optimum tuning frequency? Trying to pass 150dB



RSDXzec
03-13-2014, 08:12 AM
Working on designing an SPL box to compete with, the system belongs to my friend but we're trying to pass the 150dB mark.
Equipment is 4 American Bass XFL 15"s and 2 APSM-1500's, the subs will certainly be underpowered because the car will get upgrades later on to push more power and get more amps, however I'm trying to see how far I can get on this power with these subs.

So far from some basic calculations it's looking like 16.7cf internal before port displacement and with a quick design I did it seems I can get 15.55cf internal after port tuned to 46hz with 248 in^2 of port area.

Now his current system is 2 XFL 15"s on only 1000watts and we managed to pull off 141.6dB at 49hz in a ford festiva
(looks like this http://photos.carsguide.news.com.au/cgphotos/specs_photos/5DO.jpg).
The current box is 6.5cf internal after port tuned to 32hz with very little port area because we struggled to fit it in the boot (something miserable like only 57in^2) so by no means an SPL box.

My question is, if the loudness peaked at 49hz with that box should I tune slightly lower like 46hz then play say a 50hz tone to get the max SPL out of this car? I know maximizing volume and port area are common sense but knowing which frequency to tune to and play for SPL is something I haven't dealt with before, I usually make music boxes.

Cheers.

RSDXzec
03-15-2014, 01:04 AM
any hints/tips?
I'm planning on having variable port length for 46hz,52hz,57hz tuning so i can see which is the best, any recommendations what frequencies may be better suited?
I only get 3 shots to measure how loud the car is so im aiming to have 3 freqs.... with 57/58hz being the highest since it's basically the box with the port taken off.

VWBobby
03-15-2014, 10:09 AM
If you can find an RTA freq sweep for that car, it will show where the cabin peaks, at as far as hz. If you can find someone with a Termlab or meter, you could do a slow sweep from say 40hz to 60+ hz, and see where your particular setup peaks at. Every install is going to be different, even in the same vehicle....so a sweep is the best way to find your peak. :)

RSDXzec
03-16-2014, 07:20 AM
I know the box currently in the car made it peak at 49hz but that was with a ported box tuned to 32hz.
To do a freq sweep should I use a sealed box and use the peak frequency from that?

TaylorFade
03-16-2014, 08:10 AM
The size of the enclosure is just as much a part of the SPL peak as the "tuning".

There's a reason people use small boxes and big ports for SPL.

Toss out all of your preconceived notions about "daily" boxes and just build and test.

What kind of vehicle is this?

soundstreamer
03-16-2014, 09:09 AM
I don't think you're far off. I've build a lot of SPL systems winging it like you're planning and have had great success. All you need is the note with the best peak. The best results come when you do lots of building and testing, but you'll be ok on this one.
I'd say keep the box a bit on the smaller side(10-14cuft) with a lot of port area tuned 44-46hz burp 49-50hz. Round all corners in the enclosure, resin the inside, bracing and double baffle. When designing boxes try to make the air from the back of the sub "flow" as "smooth" as can through the port.

RSDXzec
03-16-2014, 09:10 AM
The size of the enclosure is just as much a part of the SPL peak as the "tuning".

There's a reason people use small boxes and big ports for SPL.

Toss out all of your preconceived notions about "daily" boxes and just build and test.

What kind of vehicle is this?

the vehicle was posted in the first post, it's a ford festiva, there was also a link provided, this one
http://photos.carsguide.news.com.au/cgphotos/specs_photos/5DO.jpg

As far as I know XFL's like big boxes, and i don't have a termlab so i don't have the luxury of building many boxes to test but I could try and get a one off test before a competition.

RSDXzec
03-16-2014, 09:13 AM
I don't think you're far off. I've build a lot of SPL systems winging it like you're planning and have had great success. All you need is the note with the best peak. The best results come when you do lots of building and testing, but you'll be ok on this one.
I'd say keep the box a bit on the smaller side(10-14cuft) with a lot of port area tuned 44-46hz burp 49-50hz. Round all corners in the enclosure, resin the inside, bracing and double baffle. When designing boxes try to make the air from the back of the sub "flow" as "smooth" as can through the port.

why are you recommending a smaller box? I had always thought bigger gives a better peak and I know these subs like big boxes.
I'm surprised you're recommending 49-50hz, I thought it should be higher, but again I really have no experience making comp boxes.
I will have subs up, port back, do you recommend a decent distance away from the back of the car to have a nice amount of air flow back there as well?

soundstreamer
03-16-2014, 09:24 AM
Smaller boxes have always set records.
You said 49hz was the car's peak. Why fight that?
Keep the port away from the back wall at least the height of the port. I've also seen a dude who has a world record put a deadened plate of 1/2" steel against the back wall.

RSDXzec
03-16-2014, 09:26 AM
Smaller boxes have always set records.
You said 49hz was the car's peak. Why fight that?
Keep the port away from the back wall at least the height of the port. I've also seen a dude who has a world record put a deadened plate of 1/2" steel against the back wall.

Ah ok, and it peaked at 49hz but that was using a ported box tuned to 32hz, now it's my understanding that the peak frequency of the car changes when the port of the box is tuned differently, that's why people use sealed boxes to measure peak freq.

soundstreamer
03-16-2014, 09:30 AM
I've always found peak with a sealed box, but it seams your peak shined through with a box designed for a much lower note.

RSDXzec
03-16-2014, 09:35 AM
I've always found peak with a sealed box, but it seams your peak shined through with a box designed for a much lower note.

i think that may have been because the box has very small port area.
alright i'll tune at 46hz and see if the peak freq increases.
do you think smaller boxes get better results because people can push more power to them?
I mean these subs can take 1k each so 4 k all up and they'll all only be getting 2k, possibly even 1k total if the electrical isn't upgraded soon enough.

akadj
03-16-2014, 01:45 PM
I'm doing a 150 (SEALED ON THE DASH) with one of those amps, 2 atomic 15's in a wall and a single D3100 under the hood with stock 55 amp alternator.


Your goal in easy, but i dont know if your making a wall, or removing the backseats and keeping it below the window line.

Let us know if your using stock battery, alternator, how much power wire and size of wire you have.

I'll be more then happy to help if I can.


You can always take a look at my build thread on this site for some ideas

PS. I'm pulling everything in the current build and starting a new one with something similar to what your doing, I've ordered 4 - 18's and gonna build it in my dodge Durango this time with only a couple 2kw amps for street stock 4000

RSDXzec
03-16-2014, 07:37 PM
Wow thats good, as for your questions:

I'm not making a wall, the box will be built a little higher than the window line but low enough for visibility out the rear, back seats will be removed.
The alternator is stock and will be stock at 65 amps, big 3 done with 2G and wire to amp is 4G and from batt to amp is about 4 metres.
The battery is currently stock, but there are plans to upgrade it to an optima yellow top... however i'm not sure when it's going to happen.

Thanks!

edit: I really liked your ABC box, can't believe you hit 143 with a 12 on 700w, but i'm not sure which is the build thread youre referring to.


I'm doing a 150 (SEALED ON THE DASH) with one of those amps, 2 atomic 15's in a wall and a single D3100 under the hood with stock 55 amp alternator.


Your goal in easy, but i dont know if your making a wall, or removing the backseats and keeping it below the window line.

Let us know if your using stock battery, alternator, how much power wire and size of wire you have.

I'll be more then happy to help if I can.


You can always take a look at my build thread on this site for some ideas

PS. I'm pulling everything in the current build and starting a new one with something similar to what your doing, I've ordered 4 - 18's and gonna build it in my dodge Durango this time with only a couple 2kw amps for street stock 4000

akadj
03-16-2014, 08:13 PM
Wow thats good, as for your questions:

I'm not making a wall, the box will be built a little higher than the window line but low enough for visibility out the rear, back seats will be removed.
The alternator is stock and will be stock at 65 amps, big 3 done with 2G and wire to amp is 4G and from batt to amp is about 4 metres.
The battery is currently stock, but there are plans to upgrade it to an optima yellow top... however i'm not sure when it's going to happen.

Thanks!

If it were me I wouldn't tune it any higher then 43 hz. You vehicle is gonna peak in the low/mid 50hz range. I never tune any closer then 7-10 hz from vehicle peak resonance.. I do have a couple termlab meters (1 pending sale to mass car audio) so there is a lot of testing after my initial 7-10hz lower, but its a great starting point. I have honestly about 500 hours into the build I'm scrapping.

akadj
03-16-2014, 08:19 PM
I have a Geo metro budget build

RSDXzec
03-16-2014, 08:21 PM
If it were me I wouldn't tune it any higher then 43 hz. You vehicle is gonna peak in the low/mid 50hz range. I never tune any closer then 7-10 hz from vehicle peak resonance.. I do have a couple termlab meters (1 pending sale to mass car audio) so there is a lot of testing after my initial 7-10hz lower, but its a great starting point. I have honestly about 500 hours into the build I'm scrapping.

Alright, would you also recommend a smaller box like others in this thread have said?
And how much port area should I aim for?

akadj
03-16-2014, 08:38 PM
Alright, would you also recommend a smaller box like others in this thread have said?
And how much port area should I aim for?

4 - 15's.. 18-20 cubes before any displacement.. 250 square inch of port with a little length to bring down tuning to low/mid 40's hz

My box for my 2 atomic 15's is almost 11 cubes and 200 square inches with almost now real port length other then the multiple baffles.. but tuned high 55hz because its a wall and the vehicle peaks around 65-67hz

RSDXzec
03-17-2014, 01:29 AM
4 - 15's.. 18-20 cubes before any displacement.. 250 square inch of port with a little length to bring down tuning to low/mid 40's hz

My box for my 2 atomic 15's is almost 11 cubes and 200 square inches with almost now real port length other then the multiple baffles.. but tuned high 55hz because its a wall and the vehicle peaks around 65-67hz

hmm so i was fairly close to begin with on port area and almost on volume, so would you say 14 cubes after port displacement?
and I think rather than reduce the height i'll reduce the length of the box so I have more room for the box to vent.

I'm also planning on having the port driver side, since the termlab goes on passenger side.

edit: I'm thinking based on all the recommendations so far I'm going to go with 14 cubes after displacements tuned to 44hz, kinda fits a few musical requirements I have as well.
Going on the larger side because I'll be running low power, and I did want a higher tune so 44 seems to fit.
another question I have is should I mount all four subwoofers as close as possible to the rear of the vehicle? or should I place 2 near the rear and 2 near the front? remember all subs will be facing up with the port back on driver side.

akadj
03-17-2014, 02:17 PM
hmm so i was fairly close to begin with on port area and almost on volume, so would you say 14 cubes after port displacement?
and I think rather than reduce the height i'll reduce the length of the box so I have more room for the box to vent.

I'm also planning on having the port driver side, since the termlab goes on passenger side.

edit: I'm thinking based on all the recommendations so far I'm going to go with 14 cubes after displacements tuned to 44hz, kinda fits a few musical requirements I have as well.
Going on the larger side because I'll be running low power, and I did want a higher tune so 44 seems to fit.
another question I have is should I mount all four subwoofers as close as possible to the rear of the vehicle? or should I place 2 near the rear and 2 near the front? remember all subs will be facing up with the port back on driver side.



Yes put all woofers on the same baffle and close together,.. keep them as far away from the port as possible. Keep the port as far to the driver side as you can and as far in the back of the vehicle

RSDXzec
03-17-2014, 08:46 PM
Yes put all woofers on the same baffle and close together,.. keep them as far away from the port as possible. Keep the port as far to the driver side as you can and as far in the back of the vehicle

here's a basic model of where I plan to put everything, cutouts for subs and port in the rear.
remember I'm in australia, cars here are RHD so it is in fact on the drivers side.

http://i58.tinypic.com/34ox8c6.png

akadj
03-17-2014, 08:52 PM
here's a basic model of where I plan to put everything, cutouts for subs and port in the rear.
remember I'm in australia, cars here are RHD so it is in fact on the drivers side.

http://i58.tinypic.com/34ox8c6.png

Now that I see what your building I'm not sure that port is going to be the best way to do it.

I feel that the two woofers on the driver side will unload different because of the port placement.. Straight across the bottom would probably work a lot better

And your going to need at least 12" behind the port to the hatch of the car

RSDXzec
03-17-2014, 09:12 PM
Now that I see what your building I'm not sure that port is going to be the best way to do it.

I feel that the two woofers on the driver side will unload different because of the port placement.. Straight across the bottom would probably work a lot better

And your going to need at least 12" behind the port to the hatch of the car

Alright sweet, this is how it looks.
Plans are to have 1" thick all around with 2" on the top, and probably some bracing in the centre spot there between all 4 subwoofers because that'd be the weak spot.
After bracing tuning would probably end up around 43hz, so it looks like that's the final design unless there's anything else that needs attention.

http://i57.tinypic.com/20rmljd.png

akadj
03-17-2014, 09:20 PM
When are you.plans to start the build?

And are you planning on competing in db drags?

RSDXzec
03-17-2014, 09:29 PM
When are you.plans to start the build?

And are you planning on competing in db drags?

No idea when, should be getting the subs in the mail this week or next, then getting a hold of wood I guess over the next few months. I'm in my last year of uni so study takes up a lot of my time but I will be trying to find time in between to make progress.

Yes this box will only be used for competition, it will only be in the car on the day of competitions so it will be set up the day before. This won't be used as a daily, that's why i was fine to go nuts on the tuning since music wouldn't be an issue, I have another box for daily use.

akadj
03-17-2014, 10:14 PM
No idea when, should be getting the subs in the mail this week or next, then getting a hold of wood I guess over the next few months. I'm in my last year of uni so study takes up a lot of my time but I will be trying to find time in between to make progress.

Yes this box will only be used for competition, it will only be in the car on the day of competitions so it will be set up the day before. This won't be used as a daily, that's why i was fine to go nuts on the tuning since music wouldn't be an issue, I have another box for daily use.

You already have the amps?

I'm definitely interested to see how it works out, if I'm not on here send me an email with some results at [email protected]

RSDXzec
03-17-2014, 11:06 PM
You already have the amps?

I'm definitely interested to see how it works out, if I'm not on here send me an email with some results at [email protected]

Yeah amps were bought a long time ago, except only 1 apsm-1500 will be connected until the battery is upgraded, then the second one is going in.

VWBobby
03-22-2014, 04:51 PM
Here's a little hint that few guys seem to use here in the US, but is very popular in the UK....
Try to make as many hard surfaces inside of the cabin to reflect sound towards the meter. All these floppy panels, soft interiors, vinyl, rubber, etc ABSORB sound... The last thing you want to do is absorb sound for SPL. Fiberglass or hard door panels, hard dash, etc would all give you the max SPL compared to a floppy interior absorbing 5-10+++ DB... I have seen single sub setups that can push well over 150DB and not need nearly as much power as we use in the US. Efficiency is an easy way to win an SPL comp while using the same amount of power on tap.

akadj
03-22-2014, 08:52 PM
Here's a little hint that few guys seem to use here in the US, but is very popular in the UK....
Try to make as many hard surfaces inside of the cabin to reflect sound towards the meter. All these floppy panels, soft interiors, vinyl, rubber, etc ABSORB sound... The last thing you want to do is absorb sound for SPL. Fiberglass or hard door panels, hard dash, etc would all give you the max SPL compared to a floppy interior absorbing 5-10+++ DB... I have seen single sub setups that can push well over 150DB and not need nearly as much power as we use in the US. Efficiency is an easy way to win an SPL comp while using the same amount of power on tap.


This is true, but you also have to stay within the rules of the db drags

n8skow
03-23-2014, 11:55 AM
Your objective is to compete in dbDrag with this build?
Are you familiar with the class structure?

1.21 jiggawatts
03-23-2014, 12:01 PM
if it helps any in the usa he is using a ford aspire to us.

akadj
03-23-2014, 08:41 PM
Your objective is to compete in dbDrag with this build?
Are you familiar with the class structure?

With street max class eliminated he's gonna end up in super street.. I'm scrapping the Metro Build and going to make a street stock 4KW in my suv now

n8skow
03-23-2014, 09:04 PM
My reason for asking - is why not wall this car off instead of the current plans? With the (planned) box enclosure, he'd be competing against walled vehicles anyways...

akadj
03-23-2014, 10:45 PM
My reason for asking - is why not wall this car off instead of the current plans? With the (planned) box enclosure, he'd be competing against walled vehicles anyways...

Im not sure what org hes planning on competing.. But could be super street no wall

n8skow
03-23-2014, 11:09 PM
Post #14 (http://www.caraudio.com/forums/usertag.php?do=list&action=hash&hash=14) said the box is going to be a bit higher than the window line... which will bump him to a walled class.

akadj
03-23-2014, 11:17 PM
Post #14 (http://www.caraudio.com/forums/usertag.php?do=list&action=hash&hash=14) said the box is going to be a bit higher than the window line... which will bump him to a walled class.

You are right, I didn't even remember that post. Thanks for the reminder!

RSDXzec
03-24-2014, 12:04 AM
My reason for asking - is why not wall this car off instead of the current plans? With the (planned) box enclosure, he'd be competing against walled vehicles anyways...

Because the car is a daily driver, here in Aus only vehicles allowed with a wall are utility cars like Vans Utes etc.

RSDXzec
03-24-2014, 12:06 AM
Your objective is to compete in dbDrag with this build?
Are you familiar with the class structure?

yes i have the classes from the previous competition, same people are running it so classes will be the same.

bumpasauras
03-24-2014, 12:58 AM
Dayum 150's on apsm1500 is very impressive akadj just goes to show ya it's all in the design

akadj
03-24-2014, 10:33 AM
yes i have the classes from the previous competition, same people are running it so classes will be the same.

This is the first year for the class changes, the one you seen last year may or may not have been eliminated. Just have to check i guess. But they did introduce a couple more new ones

resonate
03-24-2014, 10:44 AM
Dayum 150's on apsm1500 is very impressive akadj just goes to show ya it's all in the design

He's running 4 12s in a box designed for optimal output. If the APSM could do it, so could just about any other amplifier.

akadj
03-24-2014, 10:48 AM
Dayum 150's on apsm1500 is very impressive akadj just goes to show ya it's all in the design

It is just for competition though, so it probably doesn't sound great on music, to be honest I never even tried, there is no mids/highs. Just 2 - 15's in a wall and a single XS power D3100 under the hood with a stock 55 amp alternator!!!

But your right, is all in design and testing.



I was hoping to get more out of the car then i did, the more power I put to it the less it was gaining, at 3000rms i was at 152, at 6500rms I was at a 153.5, then I added a second, made some mods and got a 155. I was really hoping to get to a 160db off a single battery. Not bad considering I have been out of the car audio competition scene for almost a decade LOL

akadj
03-24-2014, 12:07 PM
My reason for asking - is why not wall this car off instead of the current plans? With the (planned) box enclosure, he'd be competing against walled vehicles anyways...

So I'm onto a new build, going with 4 - 18's and a pair of 2kw amps.. I got hopes of getting up to 155 in the end. Think I can get it?

What do you think the new street stock 4kw class scores will be?

n8skow
03-24-2014, 12:10 PM
Your previous post says you've already reached a 155... I'm confused...

---------- Post added at 11:10 AM ---------- Previous post was at 11:09 AM ----------

As far as future street stock scores - I have no idea man, I don't know who's building for it.

akadj
03-24-2014, 02:01 PM
Your previous post says you've already reached a 155... I'm confused...

---------- Post added at 11:10 AM ---------- Previous post was at 11:09 AM ----------

.

Previous post was the Geo metro streetmax with a wall and 2 -15's.. New build is street stock 4kw 4 - 18's and a couple 2kw amps

n8skow
03-24-2014, 02:27 PM
In a wall? Driver-side port?

akadj
03-24-2014, 02:32 PM
In a wall? Driver-side port?

The new one is going to the under the window line and behind the second row of seats, I'm going to try port facing back and subs up.. But as usual it will be tons of testing and probably many boxes

n8skow
03-24-2014, 02:37 PM
...in the Metro???
0_o

akadj
03-24-2014, 04:24 PM
...in the Metro???
0_o

Sorry for the confusion LOL.. I'm gutting the metro and going to put 4 - 18's in my dodge Durango.. Street stock 4kw i can laydown/remove third row seats so i should have plenty of room

RSDXzec
03-25-2014, 09:26 AM
This is the first year for the class changes, the one you seen last year may or may not have been eliminated. Just have to check i guess. But they did introduce a couple more new ones

the last competition was in February which I attended. I know for a fact they haven't changed.

akadj
03-25-2014, 06:52 PM
the last competition was in February which I attended. I know for a fact they haven't changed.

What class is it that are you going to compete in and what organization?

RSDXzec
03-25-2014, 06:56 PM
What class is it that are you going to compete in and what organization?

Unlimited, and Jesters Car Audio, I know the owner personally.

akadj
03-28-2014, 11:53 PM
Unlimited, and Jesters Car Audio, I know the owner personally.

I've never heard of that, where is the mic placed and are the doors and windows closed during competition?

RSDXzec
03-29-2014, 05:06 AM
I've never heard of that, where is the mic placed and are the doors and windows closed during competition?

mic on passenger side windshield, car is closed.

Here are the listed classes

STREET - 1x15", 1 or 2x12", 1 to 3x10" ect
power is 1 - 2000RMS total @ any impedance
1x battery in non factory location (if needed), + 1x battery in
factory location.
No wall.
Music ONLY but not limited
vehicals MUST be road registered.


SUPER STREET - 1x18", 2x15" 3x12" 4x10" ect
power is 1 - 2000RMS total @ any impedance
1x battery in non factory location (if needed), + 1x battery in
factory location.
No wall
Music ONLY but not limited
vehicals MUST be road registered.


PRO STREET - 1X15", 1 or 2x12", 1 to 3x10" ect
power is 2001RMS to 4000RMS total @ any impedance
upto 2x batteries in non factory location (if needed), + 1x battery in
factory location.
No wall
Music ONLY but not limited
Vehicals MUST be road registered.


PRO SUPER STREET - 1X18", 2X15", 3X12" 4X10" ect
power is 2001RMS to 4000RMS total @ any impedance
upto 2x batteries in non factory location (if needed), + 1x battery in
factory location.
No wall
Music ONLY but not limited
vehicals MUST be road registered


UNLIMITED - unlimited power, unlimited subwoofers, unlimited batteries,
music or tones are ok.
Wall is OK
can be registered or unregistered BUT must be moved around with
own power. (CAN NOT be pushed or towed to lanes)



FOR ALL CLASSES - windows open or closed.
use of usb, SD or phone is ok provided the volume is controlled
by main multimedia unit.

Street,
Super Street,
Pro Street,
Pro Super Street - multimeadia units must be used in factory location
BUT can be controlled via remote from outside the vehical.

SEDANS/TRUNK - any sedan/trunk can run there subs in/on the back
seat of there vehical provided it does not protrude past the B pillar and
does NOT sit higher than the highest point of the front seats (head rest)