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Old 01-22-2011, 02:43 AM   #13
S0C0nFused
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Quote:
Originally Posted by BowerR64 View Post
Whats hard to believe? what is batting?
If you look at the other bass drivers, you will note that they all exhibit a hump in the response curve around the 60hz area. That is the freq of there natural resonance. All drivers have a natural resonance. When you don't see this, it is evidence that a bandpass filter is in play. Generally when tuning a box, your emphasis is on avoiding any reinforcement at the Q as it will result in 'unnatural' volumes. Or, as many do for car installs, you find a bass driver with a high 'Q' (~ 100hz) as this can be used to produce really loud bass without having to push the driver/amp hard (also sounds like sh-t but most value volume over quality anymore).
Batting is like loose insulation, but without the glass fibers. You can get it at any fabric store. Do not pack it tight. Just a nice loose fill. As I said, keep it away from the spider wind and the cone. If mounting the driver vertically, you can glue some light foam on the driver as a guard.
Add > Note: This can affect the driver Q. Handy tip when tuning.

Quote:
Originally Posted by BowerR64 View Post
I can try the speaker without the crossover but im sure it would blow the tweeter without it hooked to the tweeter and im not about to do that.
Oh! Well, if you cannot split off the bass driver then don't, but normally you test without any sort of filter in-line else your not testing 'the driver'. Ditto for tweeters if you want to measure there rolloff.

Quote:
Originally Posted by BowerR64 View Post
The signal is generated by the REW program. It will to a sub type signal or a speaker type. You can set it to sweep threw what ever range of frequencies you want. say 0-20,000 or i have mine set to 40-20,000 you can also set it at any level you want. Im using the default 75db
I am not familiar with that program. But it does not matter. A quasi sign-wave is when the signal source is not pure sign, but made up of stepped voltage levels and is a measure of the amp. So instead of a slope, it resembles a stair case. Finding this is done with a O-scope. Especially if your using a PC and the integrated sound chip. Quasi-sign waves are much easier to produce than pure sign as you can imagine. The problem with them is, they can mess with pure linear devices (like crossovers and speakers). Just remember that old adage, "garbage in, garbage out".

Quote:
Originally Posted by BowerR64 View Post
This is one thing that the program doesnt do, or it can if you want to take the time is how the speaker can change at louder levels.
One speaker may have a nice curve at 75db but not at say 80-85 i probably listen to mine between 75-85db ide guess
This is harder in that, a driver will have many natural resonance points which affect the loudness at specific freq along the plot (there are also other factors like impedance, amplifier and crossover issues that may contribute). Also, you are aware that you cannot accurately measure most drivers in free air yes? (Come to think of it, did you mention what your test box size is?). You need some sort of baffle else the back wave will cancel the front wave (hetrodyne(sp?)).
Add > Note: you find the initial Q of a driver in free air if that spec is not included with the driver or unknown.

Geez! i have not thought about this stuff in ages, and it's prob getting more complex than you want or need.
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