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Bassface 15.2 ported enclosure
Bassface 15.2 ported enclosure
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Old 7th March 2019, 02:22 PM   #11
mariadumitruiulian is offline mariadumitruiulian  Ireland
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Quote:
Originally Posted by Perry Babin View Post
Have you tried connecting only one voice coil at a time to see if the output was better/worse?
No, but i will try later today. Thanks!
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Old 7th March 2019, 09:58 PM   #12
fatmarley is offline fatmarley  England
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Join Date: Aug 2003
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I just modeled it and it looks like 100ltr tuned to 35hz is fine, but I would just cover the port and make the box airtight. You'll sacrifice a bit of extension for a much tighter and cleaner low frequency response. As long as you get the crossover right, and give it enough power, it should sound great.

I've been modeling loads of subwoofers lately and yours in a 75ltr to 100ltr sealed box looks pretty good to me. Obviously i've had to guess cabin gain but without measuring your vehicle, guessing is all you can do.
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Old 8th March 2019, 06:45 AM   #13
mariadumitruiulian is offline mariadumitruiulian  Ireland
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Quote:
Originally Posted by fatmarley View Post
I just modeled it and it looks like 100ltr tuned to 35hz is fine, but I would just cover the port and make the box airtight. You'll sacrifice a bit of extension for a much tighter and cleaner low frequency response. As long as you get the crossover right, and give it enough power, it should sound great.

I've been modeling loads of subwoofers lately and yours in a 75ltr to 100ltr sealed box looks pretty good to me. Obviously i've had to guess cabin gain but without measuring your vehicle, guessing is all you can do.
Can you please tell me how much i should cover the port? Or can i make it shorter maybe? Can you also send me the simulation file, so i can see the way you did it? (and learn something )

What frequency do you think i should have the crossover? Here is a very strange thing ... i have a subwoofer output from the head-unit which already has a crossover, but with fixed cutouts of 80 , 100 and 120 Hz . I find that 80Hz is not low enough, so i need to enable LPF on the amplifier also, and bring the cutting frequency down. I read somewhere that i should not use 2 crossovers in the same time (in series) ... Maybe i should connect the amp to a normal output (on the head-unit side) also?

About the power, i use for the moment a 500W rms GZ amp, but a 1500W one is on its way. That should help a lot i think, because the gain on this one is set to ~ (or more than) 85% .

About the cabin gain, i have a Citroen C4 Grand Picasso, so it's a mono(big)volume car, and the subwoofer is in the trunk facing up ( i tried to place it like normal, facing rear, but makes no difference... in fact, sounds a little bit better facing up ).
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Old 8th March 2019, 08:11 AM   #14
fatmarley is offline fatmarley  England
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Completely cover the port and make sure the whole box is airtight. You don't want air leaking from anywhere. I've used smoke bombs to test for leaks in the past. They stink but work well. Also make sure the cabinet is well braced.

The crossover looks like it could be the difficult bit. I've only just started getting into car hifi, so don't have much practical experience, only simulations. According to my sims, If you set an active crossover to a certain frequency (say 80hz) it will react differently depending on the actual frequency response of the subwoofer used. One subwoofer may give you a 4th order roll-off another may give you a second order roll-off (the same is true with passive speakers). Playing around with the one in your head unit and amp will help i'd imagine. I've got an Dayton Omnimic v2 for measuring the frequency response, so this is what i'm planning to use when I fit my sub.
When setting up the crossover frequency and gain it's important to get the phase as near as possible. If you dont have a phase switch on your amp, just try reversing the polarity of the speaker wires going into the subwoofer. The correct phase should sound louder at the crossover frequency (unless it's a third order acoustic, but don't worry about that for now)

If I can't get my sub to play nicely with my mains, i'm going to use a combination of passive and active but you need speaker design knowledge and measuring gear for that. Even then, it's not a walk in the park.
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Old 8th March 2019, 09:25 AM   #15
mariadumitruiulian is offline mariadumitruiulian  Ireland
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Quote:
Originally Posted by Jakobsson View Post
If calculated with your present box it would be a box with a +5db spike at 35hz, a pure SPL box
If you wont to have a nice sounding box it would be built diffrent, but for SPL it is ok.
Jakobsson, can you please send me the project? I now downloaded Winisd and i want to start playing with it, so the project you simulated would help me a lot.

Thanks!
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Old 8th March 2019, 11:10 AM   #16
fatmarley is offline fatmarley  England
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I don't see a 5db peak at 35hz with a 100ltr box tuned to 35hz.

This is what happens to the frequency response, when you put a sealed subwoofer in a car - JBL GTO 804
You get a gain of roughly 25db at 20hz, so you need to think about that when your modeling your subwoofer.
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Old 8th March 2019, 02:42 PM   #17
Jakobsson is offline Jakobsson  Sweden
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internal volume is about 91liter-port volume 8liter- driver 2liter?
Close to 80liter
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Old 8th March 2019, 05:21 PM   #18
fatmarley is offline fatmarley  England
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Quote:
Originally Posted by Jakobsson View Post
internal volume is about 91liter-port volume 8liter- driver 2liter?
Close to 80liter
A smaller box gives even less bass at the tuning frequency. I just double checked the t/s parameters and they seem to be right. Not sure why you're getting a peak.
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Old 8th March 2019, 05:51 PM   #19
Jakobsson is offline Jakobsson  Sweden
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Quote:
Originally Posted by fatmarley View Post
A smaller box gives even less bass at the tuning frequency. I just double checked the t/s parameters and they seem to be right. Not sure why you're getting a peak.
My misstake!, i double checked the driver and it pretty much spot on.
-3db at 40hz

I'm sorry if i have given you headache

Ok, back to integration of sub to front.
I usually test all seperate components before integrating them together.
Make test with tone generator/rap/hip-hop with only sub playing.
What kind of music are you listening to?<- really important
Name one favorite
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Old 8th March 2019, 06:09 PM   #20
johnsurnamerobinson is offline johnsurnamerobinson
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Have a look at subwoofer diy site lots of guidance and tools you seem to know about t/s parameters so some of the spreadsheets ect, may be very usefull to you. Also deep deep in the vaults of this site you will find loads of helpfull info
Go-on build a new one its great fun and you know it makes sense
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