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PV Audio
01-02-2010, 06:47 PM
Hey guys, I need your help designing an enclosure for my car. This won't apply to about 95% of you because I do purely SQ, but the other 5% could still help. I'm fooling around with 10s now after fooling with 8s because they just didn't have enough headroom for my front components. I need clean bass, and I just can't seem to find it. ****, it's fairly straight forward for home, but car audio is a different beast. I need a way to model the transfer function of my car (it's a hatchback) because bassbox's TF is hopeless. Any ideas? I'm floating between the dayton RS-HF10 and the SS RLi-10. I sent a TC-1000 10" to mechanical failure because I think the box Q was a bit too low for the sub and it needed a bit more damping.

Either way, the point is, I need suggestions on how to get a pure SQ sub stage out of a high SQ 10" driver off 300-500 watts. I know the sound that I'm looking for, and everything I've done so far is just boomy and overpowering. So far the best I've had was my Dayton RS-HF 8 ported in 1 cube to 30hz, but I blew it easily since it couldn't keep up with my mains (even on the 300W I was feeding it). Any ideas? Thanks :)

-Dave

Toxic Tuan
01-02-2010, 11:01 PM
For pure sound quality I'd recommend the following enclosures: low compression transmission line, a high compression ported with high resonance but a low transient response, or lastly and most underrated, the aperiodic bi chamber. All of my formula's evolve around low mms and high motor strength to make it happen and it works.

BassBox Pro is completely useless in a car environment. Also make sure to compensate for the vehicle's resonance.

Tuan

PV Audio
01-03-2010, 03:44 PM
I have no room for a transmission line enclosure anyway. Nextly, I've never been a fan of the ABC enclosure. It just doesn't sound smooth enough enough for me across the entire sub bandwidth. Why would you use a high compression ported enclosure? That seems exactly opposite to what I want. If I'm allowing the system to resonate at a frequency higher than normal, that is going to cause horrible unloading issues in the subbass region which is exactly where I need the accuracy, and thus, giving me the low transient response...when I want a good transient response. OR, are you talking about, a high system Q where the low transient response really just means an overdamped system?

Toxic Tuan
01-03-2010, 04:24 PM
I have no room for a transmission line enclosure anyway. Nextly, I've never been a fan of the ABC enclosure. It just doesn't sound smooth enough enough for me across the entire sub bandwidth. Why would you use a high compression ported enclosure? That seems exactly opposite to what I want. If I'm allowing the system to resonate at a frequency higher than normal, that is going to cause horrible unloading issues in the subbass region which is exactly where I need the accuracy, and thus, giving me the low transient response...when I want a good transient response. OR, are you talking about, a high system Q where the low transient response really just means an overdamped system?

I know it sounds odd, but it works.

The ABC enclosure is only smooth if you control it properly. You have to treat as a crossover network system. Just imagine using two ported enclosures and tweak it to low transient and it'll do great. I don't think you've played with ABC boxes enough. It took me maybe 20 ABC boxes to finally understand almost everything about it. There's always a trade off in accuracy and precision vs efficiency. It becomes the key to finding that exact fine line barrier and to dial it to precisely where you want it.

High compression with port resonance is only effective with certain subwoofers. Using the effective resonance can control quite a bit of things. Take the transmission line for example. Isn't it really a gigantic resonating port? So why does it sound so good. There are a lot more factors involve. Lastly, on the transmission line. It really depends on the exact space you have, but you can have a smaller enclosure, but still retain the effective length. There are many ways this can be accomplished by slowing down the air through: turbulent or vortex flows, port redirection, or aperiodic membranes across the channel. I call it mechanical time delay. Once you've played with it enough, you can apply it to any sealed, ported, any types of enclosures really. It may sound odd, but I actually tune my sealed enclosures.

Tuan

ciaonzo
01-03-2010, 04:38 PM
I would have to agree with Tuan about going with a TL (Augspurger approach). I believe you'd be happiest with that option.

And for what it's worth, The RL-i is essentially the same as the TC1000.

Pics of mechanical failure? :)

PV Audio
01-03-2010, 04:42 PM
I know it sounds odd, but it works.

The ABC enclosure is only smooth if you control it properly. You have to treat as a crossover network system. Just imagine using two ported enclosures and tweak it to low transient and it'll do great. I don't think you've played with ABC boxes enough. It took me maybe 20 ABC boxes to finally understand almost everything about it. There's always a trade off in accuracy and precision vs efficiency. It becomes the key to finding that exact fine line barrier and to dial it to precisely where you want it.

High compression with port resonance is only effective with certain subwoofers. Using the effective resonance can control quite a bit of things. Take the transmission line for example. Isn't it really a gigantic resonating port? So why does it sound so good. There are a lot more factors involve. Lastly, on the transmission line. It really depends on the exact space you have, but you can have a smaller enclosure, but still retain the effective length. There are many ways this can be accomplished by slowing down the air through: turbulent or vortex flows, port redirection, or aperiodic membranes across the channel. I call it mechanical time delay. Once you've played with it enough, you can apply it to any sealed, ported, any types of enclosures really. It may sound odd, but I actually tune my sealed enclosures.

Tuan
Let's assume I won't be fooling with the ABC and go on to the next paragraph :)

No, a TL isn't just a gigantic resonating port as far as I know because the resonance only occurs in a ported box because there is a pressure deficit in the chamber after the air is forced out of the port. Only when you add a loading chamber to the beginning to the line (usually about 1/6 of the total line's volume) do you get any resonance effect. Otherwise, it's purely a phase inverter which is what it's supposed to do. :)

Sure you can slow down the air flow mechanically with fills, bends, membranes and whatever else you want, but that still doesn't mean it will operate as expected. There are two kinds (as I'm sure you know) of TLs: ones that have output at the port and ones that don't. The ones that don't are merely supposed to be the ideal sealed enclosure as they exhibit no resonance whatsoever at frequencies that the sub will affected by: the rear wave of the speaker is completely damped by the enclosure and the cone is therefore completely controlled by the air in the line. The ones with output at the port are usually what we're looking for, but perhaps I should be looking for the former type. The line will still be ~ the same length, however, and tuning to a speaker's 1/4 Fs when it's <30hz is still going to be a large box. :(

I use my Civic as a daily car and simply want a nice, clean and loud system: not loud speakers with loud bass. I'm using CDT HD-62Z with UpStage and I want it to be seamless like my home audio setups are and although I know that's incredibly difficult due to a car's envirionment, it cannot be impossible. I think it's just that most people have a different idea as to what SQ is than I do. :crap:

PV Audio
01-03-2010, 04:47 PM
I know it sounds odd, but it works.

The ABC enclosure is only smooth if you control it properly. You have to treat as a crossover network system. Just imagine using two ported enclosures and tweak it to low transient and it'll do great. I don't think you've played with ABC boxes enough. It took me maybe 20 ABC boxes to finally understand almost everything about it. There's always a trade off in accuracy and precision vs efficiency. It becomes the key to finding that exact fine line barrier and to dial it to precisely where you want it.

High compression with port resonance is only effective with certain subwoofers. Using the effective resonance can control quite a bit of things. Take the transmission line for example. Isn't it really a gigantic resonating port? So why does it sound so good. There are a lot more factors involve. Lastly, on the transmission line. It really depends on the exact space you have, but you can have a smaller enclosure, but still retain the effective length. There are many ways this can be accomplished by slowing down the air through: turbulent or vortex flows, port redirection, or aperiodic membranes across the channel. I call it mechanical time delay. Once you've played with it enough, you can apply it to any sealed, ported, any types of enclosures really. It may sound odd, but I actually tune my sealed enclosures.

Tuan


I would have to agree with Tuan about going with a TL (Augspurger approach). I believe you'd be happiest with that option.

And for what it's worth, The RL-i is essentially the same as the TC1000.

Pics of mechanical failure? :)
:( Then I won't be bothering with the Rl-i. I'm blaming it on my enclosure though, not the speaker. Whenever something fails, I usually end up blaming a poor design by me before thinking the driver might not be suitable until it fails like 8x like it did when I was trying to put a driver with a EBP of 38 in a large ported box when I was 14 :laugh:

I'll snap some pics of it when I go outside next, it's not pretty. It still works, it's just that **** thing overexcursed and came out of the gap completely and went back in at an angle and now it's staying that way :(

PV Audio
01-03-2010, 04:49 PM
Oh and congrats on 1k, Tuan :)

ciaonzo
01-03-2010, 04:50 PM
:( Then I won't be bothering with the Rl-i. I'm blaming it on my enclosure though, not the speaker. Whenever something fails, I usually end up blaming a poor design by me before thinking the driver might not be suitable until it fails like 8x like it did when I was trying to put a driver with a EBP of 38 in a large ported box when I was 14 :laugh:

I'll snap some pics of it when I go outside next, it's not pretty. It still works, it's just that **** thing overexcursed and came out of the gap completely and went back in at an angle and now it's staying that way :(

Sorry to hear that, I know you were excited about having it. :crap:

PV Audio
01-03-2010, 04:50 PM
And ciaonzo, Ausperger basically pioneered the TL when he was at JBL, so what do you mean by his approach when he pretty much did everything there is to do with a TL :laugh:

ciaonzo
01-03-2010, 04:52 PM
And ciaonzo, Ausperger basically pioneered the TL when he was at JBL, so what do you mean by his approach when he pretty much did everything there is to do with a TL :laugh:

Well, I assumed you would use his formulas but there are variations out there. Just wanted to be clear on the point is all. :)

ciaonzo
01-03-2010, 04:58 PM
I'm also going to have to kindly disagree with both of you on the point of BB being useless for the automobile environment. It matches the transfer function of my Camry nearly spot-on and should only need mild tweaking for most sedans and hatches. Just find the transfer function of your vehicle and import the file. John at Acoustic Elegance was kind enough to provide me with the measurement of my vehicle's transfer function, maybe he has others.

PV Audio
01-03-2010, 05:00 PM
I never said it was useless, I just said I can't figure out how to work the **** thing to make it useful for my car :laugh:

ciaonzo
01-03-2010, 05:03 PM
lulz

You're a good kid, PV.

Shoot me the dimensions for the amount of space you'd be willing to sacrifice for a TL and I'll kick some numbers around to see if I can squeak one in there. Once you have a driver, of course.

Toxic Tuan
01-03-2010, 05:20 PM
I'm also going to have to kindly disagree with both of you on the point of BB being useless for the automobile environment. It matches the transfer function of my Camry nearly spot-on and should only need mild tweaking for most sedans and hatches. Just find the transfer function of your vehicle and import the file. John at Acoustic Elegance was kind enough to provide me with the measurement of my vehicle's transfer function, maybe he has others.

I guess useless isn't the proper wording. There are a couple of other approaches that seems to work much better...well at least for me. You care to share your vehicle's transfer function and the year of the Camry? We really need a complete database.

Tuan

ciaonzo
01-03-2010, 05:32 PM
I guess useless isn't the proper wording. There are a couple of other approaches that seems to work much better...well at least for me. You care to share your vehicle's transfer function and the year of the Camry? We really need a complete database.

Tuan

Sorry, I tend to be pretty literal at times. No doubt, there are more exacting approaches but modeling is a nice tool to have when you can get it to cater to your needs, even on a rough level. I always use me ears to do final tweaking anyhow. :)

Gimme a second to load that graph into the bucket, Tuan.

Toxic Tuan
01-03-2010, 05:36 PM
Let's assume I won't be fooling with the ABC and go on to the next paragraph :)

No, a TL isn't just a gigantic resonating port as far as I know because the resonance only occurs in a ported box because there is a pressure deficit in the chamber after the air is forced out of the port. Only when you add a loading chamber to the beginning to the line (usually about 1/6 of the total line's volume) do you get any resonance effect. Otherwise, it's purely a phase inverter which is what it's supposed to do. :)

Sure you can slow down the air flow mechanically with fills, bends, membranes and whatever else you want, but that still doesn't mean it will operate as expected. There are two kinds (as I'm sure you know) of TLs: ones that have output at the port and ones that don't. The ones that don't are merely supposed to be the ideal sealed enclosure as they exhibit no resonance whatsoever at frequencies that the sub will affected by: the rear wave of the speaker is completely damped by the enclosure and the cone is therefore completely controlled by the air in the line. The ones with output at the port are usually what we're looking for, but perhaps I should be looking for the former type. The line will still be ~ the same length, however, and tuning to a speaker's 1/4 Fs when it's <30hz is still going to be a large box. :(

I use my Civic as a daily car and simply want a nice, clean and loud system: not loud speakers with loud bass. I'm using CDT HD-62Z with UpStage and I want it to be seamless like my home audio setups are and although I know that's incredibly difficult due to a car's envirionment, it cannot be impossible. I think it's just that most people have a different idea as to what SQ is than I do. :crap:

In regards to forced air: there is a clear distinction between a laminar and a turbulent flow. What you do is find the highest velocity point using compression and still retain an acceptable laminar flow. Design the cross area for that flow rate and you're off to a great start. From there start modifying for the small box.

TL: A transmission line is only useful if the port has output. "Using the port to control the cone" isn't a good approach at all. There are many other ways to do so such as: Passive radiator, Aperiodic Membranes in a sealed box, IB with back wave dispersion behind the woofer.

Here is something to think about for you: What happens went you drill small holes down the center line in the port a few inches away from each other. Now make the holes bigger and stuff it will foam or high density membranes. Now do this for a transmission line. Give it a try. :)

Tuan

ciaonzo
01-03-2010, 05:38 PM
Here you go. I don't have any background info on what standard was used as far as driver/enclosure but I trust John's abilities and it's been pretty useful to me. To my understanding, the green line represents all windows up.


http://i704.photobucket.com/albums/ww43/ciaonzo/Temp/Camary4windowscompare.gif


Vehicle is a 2005 Camry SE.


http://carsmedia.ign.com/cars/image/article/645/645484/toyota-camry-se-20050825061523111.jpg

Toxic Tuan
01-03-2010, 06:33 PM
Awesome. Thanks for the graph.

Tuan

ciaonzo
01-03-2010, 06:34 PM
Awesome. Thanks for the graph.

Tuan

Nice to be of some help.

PV Audio
01-04-2010, 01:14 PM
Me next! :)

boogeyman
01-04-2010, 02:46 PM
PV do you have an RTA.........or Tru RTA for a laptop
measuring transfer function is quite simple if you have an RTA..........Tru rta and a behringer mic can be purchased for around $100

PV Audio
01-04-2010, 03:15 PM
I, sir, have not a spectrum analyzer nor do I plan on buying one for my car since I don't do car audio hardly at all.

PV Audio
01-04-2010, 03:16 PM
10 Courtesy points to whoever can tell me what sub is in my avatar picture (ciaonzo you're exempt :D ).

mobeious
01-05-2010, 12:32 AM
TC1000 8"

terminals are throwing me off

PV Audio
01-05-2010, 03:55 AM
TC1000 8"

terminals are throwing me off
BZZT! Next!