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amp power vs. sub handling


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3 replies to this topic

#1 of 4 OFFLINE   msheabel

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Posted November 20 2006 - 11:59 AM

hello

i have been looking at a dayton titanic 15in sub and a bash 500w amp. the dayton sub has a 800 watt rms. does the bash amp have enough power to push the dayton sub. because most speakers have a wattage higher than your typical reciver/amplifier. for example most recievers put out 100-150watts per channel. and floor standing speakers are around 250-the limit. what is the conseqences of going to low on your amp. or is 500 watts just fine.

thanks

#2 of 4 OFFLINE   Mattak

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Posted November 22 2006 - 04:26 PM

You should be just fine. Going from 500 to 800w will only gain you ~2db. I run a 1600w adire tumult off of a 250w plate amp and I'm happy with it (coming from a guy with 2400wrms available to a 1600w adire brahma in car).

#3 of 4 OFFLINE   Robert_J

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Posted November 23 2006 - 02:05 AM

The wattage rating on a sub is how much continuous power it can handle without the voice coil melting. You can send it much more power in bursts.

How much power a sub needs to move is a completely different story. When watching a movie, you will rarely send your sub more than about 10 watts. During the action sequences, you will send bursts up to the max of what your amp can put out. That won't melt anything. What it can do is move the cone past its maximum excursion limits. When designing a sub, you need to know how much power and at what frequency the sub will reach its limits. Go past the limits and you tear a spider or bottom the voice coil. Neither are good. Plug the numbers into WinISD or Unibox (my favorite) and run some simulations.

Remeber that the BASH 500w amp as a sub-sonic filter set at 30hz. You will want to change that to something in the 20hz range (enclosure dependant).

-Robert

#4 of 4 OFFLINE   David_P

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Posted November 23 2006 - 03:23 AM

you need to model the sub you want to use in the size of enclosure/tuning you want to use. Use Unibox (spreadsheet) or WinISD Pro (both free).

For both sealed and ported boxes, it is possible to have the box either power-limited (amp will clip before driver bottoms) or excursion-limited (driver bottoms before amp clips). I would suggest that the former (power-limited) is safer.

It is easier to achieve this with a sealed box... you simply make the box smaller and smaller until the driver will no longer bottom with the amp you've chosen.

With ported boxes, making the box smaller helps, to a point. But below port tuning frequency, the driver unloads and is easily over-driven. Thus the growing trend for hugely over-sized/very-low-tuned ported boxes which are called LLT (large-low-tuned)... these are usually sonotube designs and follow a design popularized by Steve Callas. If you google LLT + Steve Callas you'll find a bunch of threads about this kind of design. They have the advantage of not unloading until very very low frequencies, but even they may need some kind of high-pass filter to tame infransonic overloading. And unfortunately, many plate amps don't have easily modifiable high-pass filters.

David