6th Order Bandpass for Alpine Type R - Video Page 3!

[SnowDrifter]

Hmm... Then yes, I would agree, that BL number sounds a bit low.

Just a quickie tip - motor force is BL²/Re

That's while dual 2 coils will have more BL than a dual 1 coil. Not because it has any more motor force, but because the BL has to increase to keep the motor force the same

[Kyblack76]

God i like this thread.....

[the_garynator]

HThat's while dual 2 coils will have more BL than a dual 1 coil. Not because it has any more motor force, but because the BL has to increase to keep the motor force the same

Thanks for sharing that quickie! I knew that it varied depending on impedance, but never knew the reasoning behind it, never got around to researching it. Thanks for saving me some time

[the_garynator]

Retuned to 27hz for rear chamber and 61hz for the front chamber. Also realized that I had cut the original rear ports 5in too short, so it was tuned to 26hz instead of 25.

Hit 140.2db sealed at the dash with the car off at 29hz!

I'll be posting a comparison of all of the term lab results as soon as I get them into the computer. but the tuning changes made big gains in the upper frequency range. Instead of dropping off at around 65hz, it now has good output up to 75hz and doesn't completely drop off till around 78hz. It also has helped a lot in the mid 30hz range, less of a dip in spl and seems to have better control in that area too.

I'm going to be heading out to my shop today and adding another 2 4" port to the rear chamber and metering for changes (tuning Freq may change unfortunately). If I end up having time I'll be also adding another port to the front chamber and retesting again.

[Quiet]

shit's beast.

and complaining about your sub unloading at 3x rms

[tdsa23]

That score with the car off and on a Type R12 that's beast Cant wait to see what the lvl5 does.

[stroupe79]

this 6th is quite impressive for the typeR and cabin space size pulling a 140....waiting for the level5 build for sure!

[the_garynator]

Thanks guys! All the interest is encouraging.

I haven't had time to get the results put into the computer yet from the tuning changes, but I did make some progress on the next changes (doubling port area for the rear chamber).

here are some teaser pictures of what is to come later this week:

^mockup of layout...the cardbord box represents the current box, the black ports laying in front represent the current small chamber side ports. had to get creative with the ports in order to fit long enough ports to get a 29hz tune with this much port area. Only thing that sucks is that It has limited how much port area I can cram in the front chamber due to space constraints and other considerations. Can't wait to see what kind of difference doubling the port area in the rear chamber makes!

[Kyblack76]

Very cool.

I was hoping you'd tweak, and see.

Whats cool, is what you render and plot, you ALMOST make true, in real life. Thats pretty cool. The ability to test on the screen, and not in your car, and still get expected results is WAY cool. Cuts down on testing for months, all by the time you have a Pepsi.

Great great thread man. Well done.

[the_garynator]

Very cool.

I was hoping you'd tweak, and see.

Whats cool, is what you render and plot, you ALMOST make true, in real life. Thats pretty cool. The ability to test on the screen, and not in your car, and still get expected results is WAY cool. Cuts down on testing for months, all by the time you have a Pepsi.

Great great thread man. Well done.

Thanks man! this is exactly what I'm trying to do. I hate the guess and check method, which is what it seems like 99% of people use. I'd rather spend the time acquiring the measurement tools and understanding how things work (i.e. box rise, cabin gain, etc.) versus making a change, testing, making another change, retesting, etc. It's like tuning an engine from scratch...you'll be much closer and require much less effort if you do calculations using things like volumetric efficiency, etc than if you just guess.

I'm just happy that I finally have gotten all of the tools to be able to measure my results and compare them with the predicted results!

EDIT:

a better analogy...tweaking a box/setup with just a termlab is like tuning an engine using a wideband o2. Takes a lot more trial and error than if you have a dyno and a wideband and a piece of software that predicts how changes will affect performance.

Edit 2: The guess and check method isn't so bad when you're just looking for burping one number, but when you factor in looking for full response, it increases the amount of time using the guess and check method exponentially, basically making it unfeasible as an option for anyone not 100% dedicated to car audio.

Also, I am by no means trying to disrespect anyone or start any arguments, just stating my methodology..and doing my best to verify my own theories.