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Author Topic: cabinet rating and power amp suggestions  (Read 423 times)

John Roll

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cabinet rating and power amp suggestions
« on: June 18, 2018, 10:06:43 am »

A friend of mine replaced the speakers in his old CSX community subwoofers rated at 300 watts each with some 600 watt speakers. Since there are two per cabinet would the cabinet wattage then be 1200 watts? If so the recommended amplifier per side should be rated around 2000 Watts into that mode (which I believe is 4 Ohms) ,correct?

Thanks,
John
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Rick Powell

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Re: cabinet rating and power amp suggestions
« Reply #1 on: June 18, 2018, 10:23:17 am »

A friend of mine replaced the speakers in his old CSX community subwoofers rated at 300 watts each with some 600 watt speakers. Since there are two per cabinet would the cabinet wattage then be 1200 watts? If so the recommended amplifier per side should be rated around 2000 Watts into that mode (which I believe is 4 Ohms) ,correct?

Thanks,
John

If the replacement 600w speaker units are 8 ohm and wired in parallel, the cabinet would be nominally 4 ohms at 1200 watts. Some people subscribe to the "don't exceed the rated speaker power" method of sizing power amps, and others subscribe to the "use 1.5x" or thereabouts the rated power, with the understanding that they need to watch the maximum voltage delivered to the speakers by limiting, attenuation, etc. The other comment that is sure to be made here is the suitability of the replacement speakers to the given cabinet design. The speaker parameters should be carefully matched to the cabinet design and what is intended to achieve; some speakers with "double the rating" may not perform as expected if they are not a good match for the cabinet or the intended bandwidth of use.
« Last Edit: June 18, 2018, 10:27:31 am by Rick Powell »
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Bob Faulkner

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Re: cabinet rating and power amp suggestions
« Reply #2 on: June 18, 2018, 10:29:49 am »

A friend of mine replaced the speakers in his old CSX community subwoofers rated at 300 watts each with some 600 watt speakers. Since there are two per cabinet would the cabinet wattage then be 1200 watts? If so the recommended amplifier per side should be rated around 2000 Watts into that mode (which I believe is 4 Ohms) ,correct?

Thanks,
John
Is the 600 watts -- continuous, RMS, or peak?  This will help in determining an amp.
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David Morison

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Re: cabinet rating and power amp suggestions
« Reply #3 on: June 18, 2018, 10:35:43 am »

A friend of mine replaced the speakers in his old CSX community subwoofers rated at 300 watts each with some 600 watt speakers. Since there are two per cabinet would the cabinet wattage then be 1200 watts? If so the recommended amplifier per side should be rated around 2000 Watts into that mode (which I believe is 4 Ohms) ,correct?

Thanks,
John

Unfortunately it's not necessarily as simple as following the actual driver power rating.

The original cabinet may have been built with ports that were big enough to handle the amount of air movement created by the lower powered original drivers, but which might be too small to function efficiently without making extraneous noise when driven to higher SPL's. In that case, there would be little to no benefit in using higher powered drivers.

Or, the new drivers might have T/S parameters that don't play well with the net internal volume & tuning frequency of the box and which could run out of linear excursion at less than their full power, again leading to extraneous noise (distortion) being produced before the increased power handling could be fully exploited.

Modelling the cab (with the parameters of the new drivers) in something like WinISD would be the minimum required to see if either of those complications were likely to arise.

Moving on to the cabinet itself, it may have been rigid enough not to vibrate or colour the sound when driven to it's designed target SPL, but if driven louder, may no longer achieve that.

Even if those hazards are avoided, it doesn't follow that the new setup will be louder than the old one: some of the things that can be done to a driver to make it handle more power (eg bigger voice coil, to make a sweeping generalization) can add weight to the moving parts, which, if not compensated for by a more powerful magnetic structure, can result in the driver being less efficient than a lower powered one.

Not to mention the fact that 600W vs 300W is only 3dB, which is (again, generally) only just noticeable as an increase in volume, so very little real benefit may be gained by such a driver swap.

But, if all of those factors are clear, then yes, the new version would be 1200W @ 4Ω and a 2000W/channel amp would be in the ballpark for typical usage.

Of course, if the old drivers were already toasted, then any working driver will at least produce a bit more sound, whatever it actually sounds like  ;)

HTH,
David.
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Chris Hindle

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Re: cabinet rating and power amp suggestions
« Reply #4 on: June 18, 2018, 12:35:58 pm »

A friend of mine replaced the speakers in his old CSX community subwoofers rated at 300 watts each with some 600 watt speakers. Since there are two per cabinet would the cabinet wattage then be 1200 watts? If so the recommended amplifier per side should be rated around 2000 Watts into that mode (which I believe is 4 Ohms) ,correct?

Thanks,
John
If I'm not mistaken, those are full range boxes, 3 way.
The CSX Subs I've seen were 4 drivers.
If they're the 3-way boxes, what did you do to upgrade the mids and tweeters ?
They will not last very long at double the power.
As others have mentioned, what was done to the porting to accommodate the new drivers ?
Chris.
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David Morison

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Re: cabinet rating and power amp suggestions
« Reply #5 on: June 18, 2018, 05:43:13 pm »

If I'm not mistaken, those are full range boxes, 3 way.
The CSX Subs I've seen were 4 drivers.
Chris.

Just had a quick check, the CSX40-S2 and 56-S2 were indeed dual 15" subs, so it's presumably one of those the OP's friend is dealing with.
The quad 15" sub was the CSX60-S2.

FWIW,
David.
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Luke Geis

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Re: cabinet rating and power amp suggestions
« Reply #6 on: June 18, 2018, 08:22:59 pm »

I go with the 75% of peak power as my go to for amplification. I would bet based on the numbers you stated, that the peak power is 2,400 watts each. So if wired in parallel, they would have a peak wattage rating of 4,800 watts. I would go for and amp between 2,400 watts and 3,600 watts to power just the woofers, the mids and high sections surely will not tolerate that kind of power though.

Now if that rating you gave us was the program rating, the numbers change. That would mean the peak rating is likely 1,200 watts each with a total peak wattage of 2,400 which would mean you need an amp capable of between 1,200 watts and 1,800 watts.

While I tend to go with the 75% of peak wattage rule myself, I typically suggest to others that sticking close to the program rating is perhaps a safer option. YMMV?
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Re: cabinet rating and power amp suggestions
« Reply #6 on: June 18, 2018, 08:22:59 pm »


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