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this size and volume of your vehicle is gonna effect it. I know some programs add a function for cabin gain, but I dont know how acurate they are.

in general you can expect 10-20dB of cabin gain at the tuning freq for your vehicle.
 

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in all honesty i think it is easier to actually find your vehicles cabin gain frequency than it is to find something by using this site's "search" function. once you figure out how to do it of course.

did you search?

i did not too long ago, last week perhaps. i found it on this site. try looking for "transfer function" as well.
haven't done it myself yet since it has been all cold and rainy lately. i did however find a graph of the FR for a very similarly designed GM vehicle and found it to be in the neighborhood of 43-45hz. dropped that by a few db's and a lot of muddiness and excessive "boom" in some music to go away. seems to have helped with some of the upfront bass as well.
 

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Discussion Starter #4
did you search?
did a search the best info i could find was to buy a meter reader from radioshack (i'll get one from amazon.co.uk or something) ... that was about it. just wanted to know where i'd go from there really. how much to spend on a good level meter? are there any programs that already have a function for cabin gain? how accurate is it? etc, etc

So you record the sound, at a given frequency (GM 43-45hz) take that into account when building and somehow eliminate or lower the db at that given frequency??
 

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Use the Rad shack meter as a mic and a program like Room EQ Wizard... measure the nearfield response of the sub you have (I think a sealed box would be easier to base off of) and then measure the response with the sub in your vehicle at the seated position.

The difference in measurements will be the amount of cabin gain you can expect.
 

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Extremerevolution will model boxes for you and use specific info from your vehicle for boundary loading etc. He has a thread running on it.

I factored in the cabin gain when designing my system and ended up running my sub in a 0.125cf box in the front footwell. The design is unusual as it dictates the FB has to be HIGHER than the range you intend to play the subwoofer. So my subwoofer's output starts to roll off ABOVE 100Hz, the sub system has an F3 of 76.84Hz, Fb of 76.32 (modeled not measured yet) The sub only just fits in it the box, but it handles everything I throw at it and is flat from 30Hz to 63Hz where it's LPF'd (measured with pocket RTA and white noise) google Linwitz Transform.

I was fortunate that I found my transfer function mapped out by Andy W in the graph mentioned above, so just entered the info into BBpro.

If you are measuring yourself make sure you measure the response outside the car in a large open space with no boundaries near by as they can skew results. Personally I'd keep the measuring distance the same, so measure the distance from your sub to your head and then when you do the outside measurements keep the mic at the same distance. Otherwise just make sure you match the amp voltage output in both situations and make sure you use the same test tone.

Good luck

Edit: sealed/ported/bandpass box will make no odds in your measurements-you're comparing the same sub's relative output in and out of your car.
 

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i believe patrick bateman has a post or two somewhere around here claiming great success with having subs placed in enclosures just big enough to house the speaker and still managing to have decent response.

baron, just read your other thread/post, you built that little circuit i take it? how exactly did you model that in BBpro with cabin gain if you don't mind me asking? i don't think i got it right. like i mentioned in my previous post i found a pic of a similar gm car and tuned accordingly with so-far-so-good success.

bassbox 6 pro has a section where you are able to input values for cabin gain if you know them so that you may tune/design to adjust for that.

for my situation, i simply looked at the graph of the similarly built vehicle and noticed roughly a 15db increase at ~43hz compared to ~60hz. brought that area down a bit, boosted near the subsonic point a bit and thus far, things are good.
 

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baron, just read your other thread/post, you built that little circuit i take it? how exactly did you model that in BBpro with cabin gain if you don't mind me asking? i don't think i got it right. like i mentioned in my previous post i found a pic of a similar gm car and tuned accordingly with so-far-so-good success.
No, with a car there is no need for the circuit-I'm using the cabin gain instead of the circuit. I had thought I'd need some EQing too but on initiall listening I've needed none. For yourself a similar car is possibly good enough to have the same results as me-I've added some more to the other post

bassbox 6 pro has a section where you are able to input values for cabin gain if you know them so that you may tune/design to adjust for that.
That's what i did using Andy W's graph as a guide, if you really wanted to you could measure yours for more accurate results-but do consider that my modeled output is MUCH peakier than my measured response in car-though this could be down to an RTA on my phone with no seperate mic

for my situation, I simply looked at the graph of the similarly built vehicle and noticed roughly a 15db increase at ~43hz compared to ~60hz. brought that area down a bit, boosted near the subsonic point a bit and thus far, things are good.
Glad that's working for you:)
 

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Discussion Starter #9
I was fortunate that I found my transfer function mapped out by Andy W in the graph mentioned above, so just entered the info into BBpro.
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So what are good Sub software. I got WiniSD pro, but the WiniSD Beta has a better 'pre' selected choice of subs (just messing around and clicking buttons at the moment).

Bassbox Pro but that's like $150?? any others. I see varrying opinions about WiniSD.
 

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WinISD is just fine. I know UniBox is pretty good also.

I like REW for measurements, but you'll need to buy a mic or radioshack spl meter.
 

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I factored in the cabin gain when designing my system and ended up running my sub in a 0.125cf box in the front footwell. The design is unusual as it dictates the FB has to be HIGHER than the range you intend to play the subwoofer. So my subwoofer's output starts to roll off ABOVE 100Hz, the sub system has an F3 of 76.84Hz, Fb of 76.32 (modeled not measured yet) The sub only just fits in it the box, but it handles everything I throw at it and is flat from 30Hz to 63Hz where it's LPF'd (measured with pocket RTA and white noise) google Linwitz Transform.
have you got a picture you could share?
 

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I didn't care for WinISD, Bass Box Pro is okay, but for cabin Gain and overall woofer box design...

ExtremeRevolution turned me onto a BASSA$$ free program that I like better than the rest.
 

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I didn't care for WinISD, Bass Box Pro is okay, but for cabin Gain and overall woofer box design...

ExtremeRevolution turned me onto a BASSA$$ free program that I like better than the rest.
care to share?
 

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Will get something up next week-busy weekend, you will laugh when you see my 1st attempt at trimming a box-looks like Stevie Wonder and an elephant with premature ejaculation issue had a field day with it! Fortunately the bit you see looks fine!
 

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Will get something up next week-busy weekend, you will laugh when you see my 1st attempt at trimming a box-looks like Stevie Wonder and an elephant with premature ejaculation issue had a field day with it! Fortunately the bit you see looks fine!
Like I said anything (pics) would be a help. Still looking to get into box building myself because no one in my area does it and all the kids are wasting their money on ... not good stuff. My friend has just spent £600 on a Vibe Black Air 12 sub, Vibe Black Death 6x9's and an amp. When he heard my system he nearly broke down in tears (Morel Tempo 6 mounted in the kick panel, DDLE312, JL audio amp).

I really want to get into this though. been reading up a lot just need to find space and tools now.

As for me I need to rehouse some of my enclosed subs. But I promised my friend when i get started I'll build him an enclosure for his Black Air, however with a QTS 0.632 i'm thinking a sealed enclosure might be best.

Blackair Enclosures | VIBE Audio


Back to Cabin Gain


So once i've got my figures for cabin gain, what do I do then? what do i need to do to make the bass less 'boomy'?
 

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Build the enclosure for the curve you want given the measurements you get for cabin gain. I think a "house curve" sounds the best...
 

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Like I said anything (pics) would be a help. Still looking to get into box building myself because no one in my area does it and all the kids are wasting their money on ... not good stuff. My friend has just spent £600 on a Vibe Black Air 12 sub, Vibe Black Death 6x9's and an amp. When he heard my system he nearly broke down in tears (Morel Tempo 6 mounted in the kick panel, DDLE312, JL audio amp).

I really want to get into this though. been reading up a lot just need to find space and tools now.

As for me I need to rehouse some of my enclosed subs. But I promised my friend when i get started I'll build him an enclosure for his Black Air, however with a QTS 0.632 i'm thinking a sealed enclosure might be best.

Blackair Enclosures | VIBE Audio


Back to Cabin Gain


So once i've got my figures for cabin gain, what do I do then? what do i need to do to make the bass less 'boomy'?
I'd cry if I'd spent any money on Vibe! basszone in wolves build "pretty" good boxes, if you give them the dimensions they'll make what you want. Only pinned together, though you can order un-carpeted and screw them up yourself if you were concerned. I had mine made by a carpenter mate of mine, more than basszone, but better built.

Damn iphone has dumped pics of box on home PC, will drag them off tonight. Here's a pic of the RTA shot, bear in mind this has been done with ZERO tuning, gains set by turning down to minimum(!) and artbitary crossover points selected, tweeters not mounted, just in trial positions-so I should easily be able to smooth the dip at 250Hz and hump at 1KHz. The screenshot shows box modeled with and without cabin gain and outer dimensions of box.
 

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your program (bbp6) looks a wee bit diff'rent than mines.
 
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