I am getting closer and closer to that 250W plate amplifier, which means that the S10 Big Block Subwoofer is about to become a reality.
Background Info:
I once had a short stint of interest in subwoofers that operated similarly to the ELF subs made by Bag End Loudspeakers. During this time, I did some research on my current woofer driver, a 10" Blueprint 1001 from the first-generation (which had a double-stacked magnet system and very long-excursion suspension system). The findings were very promising. I found that in only a single cubic foot, I could achieve a critically-damped Q of 0.5 that, with proper amplifier equalization, could be flat to 25 Hz and have an F3 of 20, while still boasting a transient-perfect Q alignment. I asked around here and while the excursion capability of the driver was in doubt at first, it was finally determined that the woofer has what it takes for this type of application. Because achieving this kind of output from a small sealed box is basically a matter of brute force, I needed something that could supply the 1001's 300W appetite. I eventually settled on the 250W Parts Express plate amplifier with 6 dB of bass boost. I plotted the average frequency response with the woofer in the box and the amplifier's bass boost and found that it was sufficient for reaching 25 Hz. I also cooked up a plan to hot-rod the thing by wiring in a 1.0-Farad automotive capacitor to stiffen the power supply. The remark was made that this is outstanding performance from a 10" in a 1-cubic-foot box.
Ok, now before I drop $150 on the plate amp, I want to know:
Will my driver in the 1-cubic-foot box experience the "hot oven" effect (where the internal temperature of the box rises to very high temperatures and severely limits the ability of the driver to cool itself)? I don't want to burn it up if I can avoid that.
Background Info:
I once had a short stint of interest in subwoofers that operated similarly to the ELF subs made by Bag End Loudspeakers. During this time, I did some research on my current woofer driver, a 10" Blueprint 1001 from the first-generation (which had a double-stacked magnet system and very long-excursion suspension system). The findings were very promising. I found that in only a single cubic foot, I could achieve a critically-damped Q of 0.5 that, with proper amplifier equalization, could be flat to 25 Hz and have an F3 of 20, while still boasting a transient-perfect Q alignment. I asked around here and while the excursion capability of the driver was in doubt at first, it was finally determined that the woofer has what it takes for this type of application. Because achieving this kind of output from a small sealed box is basically a matter of brute force, I needed something that could supply the 1001's 300W appetite. I eventually settled on the 250W Parts Express plate amplifier with 6 dB of bass boost. I plotted the average frequency response with the woofer in the box and the amplifier's bass boost and found that it was sufficient for reaching 25 Hz. I also cooked up a plan to hot-rod the thing by wiring in a 1.0-Farad automotive capacitor to stiffen the power supply. The remark was made that this is outstanding performance from a 10" in a 1-cubic-foot box.
Ok, now before I drop $150 on the plate amp, I want to know:
Will my driver in the 1-cubic-foot box experience the "hot oven" effect (where the internal temperature of the box rises to very high temperatures and severely limits the ability of the driver to cool itself)? I don't want to burn it up if I can avoid that.
Make sure that the rail voltage of the amp doesn't exceed the voltage rating of the caps. The plate amp can easily have rail voltages of 40VDC or more while those automotive 1F caps are typically rated for only 20VDC. Also you'll have to make some kind of "soft-start" current limiting circuit or you'll pop the fuse on power-ups.BAM said:
That will depend on the design of the amp. I would assume this not to be a problem with a plate amp which is designed (you would hope) for such installations.BAM said:
My question was about the driver. The box seems very small, and I was wondering if a high-power input signal would cause the motor (with it's vented pole piece and high air flow through the motor) to heat the air in the box to the point where the driver could no longer adequately cool the voice coil.
I found three different sets of parameters for Blueprint 1001. All of them seem to indicate that the driver is relatively inefficient (85.6db-W-m). This being the case, I would have to say that if you plan on running these speakers at high volume for any length of time that heat in the box/driver could become an issue. They are suppose to take 250W RMS, but for how long, and how accurate is that figure, and how hard do you plan on driving them?
Well, most high-Mms and Low-Fs drivers are fairly inefficient, but it seems like Parts Express gets away with the Titanic 10" in a similarly sized sealed box with the same amp that I am using but it does have a much higher sensitivity (90dB 1W/1m).
When you said "Big Block S10" in the title, I thought this was gonna be a post about Chevy S10 with a 4.3L V6 or a V8 in it. Oh well 🙄
Isn't 1 Farad a really whole hell of alot capacitance (for this application)?!? Your gonna have a cap that costs almost as much as the plate amp!
Isn't 1 Farad a really whole hell of alot capacitance (for this application)?!? Your gonna have a cap that costs almost as much as the plate amp!
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