Question About Appropriate Amp Power For Sub

[srosenberg]

Originally Posted by sreten

Hi, I'll repeat power needed for max SPL is totally independent of any EQ, rgds, sreten.

Hi Sreten,

thanks for the inputs... i'm getting some mixed messages here - at least it seems that way to someone with next to no knowledge of this stuff (ME).

you are suggesting the correct approach to determine the max power that can be used would be to model the driver in the correct enclosure size, then without applying any eq whatsoever - High Pass, Low Pass, Linkwitz Transform, etc - increase the 'System Input Power' until the cone excursion reaches the Xmax at the lowest expected frequency that will be reproduced by the driver?

in this case, with 625 Watts of input, i reach the Xmax at 20 hz. since i will be high passing above that, is this safe? see attached...

[sreten]

Originally Posted by srosenberg

If I do not use the LT, I can use more power prior to exceeding the Xmax.

Hi,

Whatever the confusion the above is simply wrong. Power at Xmax is fixed.

rgds, sreten.

[revboden]

I just inputted the TS specs you provided WinISD dosent like them at all. I'll try to model this in BBP. WinISD does model PEQ correctly, input fc =30 Q=1 gain =5.7db

[weltersys]

Originally Posted by srosenberg

thanks very much for that explanation... let me see if i have this right using two of my proposed builds...

TC Epic 10
Max Input Power to Not Exceed Xmax: 280 Watts
Max Amplifier Apparent Load Power (VA): 340 Watts
It's therefore safe to use an amp up to 340 Watts without risking exceeding the Xmax?

Dual TC Epic 8
Max Input Power to Not Exceed Xmax: 375 Watts
Max Amplifier Apparent Load Power (VA): 212 Watts
It's therefore safe to use an amp up to 375 Watts without risking exceeding the Xmax?

sorry for all the rookie questions... first timer here!

Amplifiers deliver voltage to speakers which have an impedance that varies with frequency.
Voltage squared divided by the impedance = power in watts.
The amount of voltage to reach or exceed Xmax is different at each frequency, looking at impedance and excursion curves gives you an idea what power is needed to reach Xmax at a given frequency.
At higher frequencies, excursion is less for a given SPL, so the speaker will burn before it breaks.
Down low, Xmax often will be exceeded well before Pmax.

How much power to use depends on program material, if the material is upper bass, very large power peaks are not a problem for most woofers, while down low, using much more power than required to reach Xmax will result in distortion and potential mechanical damage.

Big LF boosts also make it more likely to clip the amplifier, a clipped amp can often put out much more than it's rated power.

[revboden]

Something about these specs is wrong. power at 33hz Xmax is up in the 900w range in one sim and ~300w in another...

[sreten]

Originally Posted by srosenberg

Hi Sreten,

thanks for the inputs... i'm getting some mixed messages here - at least it seems that way to someone with next to no knowledge of this stuff (ME).

you are suggesting the correct approach to determine the max power that can be used would be to model the driver in the correct enclosure size, then without applying any eq whatsoever - High Pass, Low Pass, Linkwitz Transform, etc - increase the 'System Input Power' until the cone excursion reaches the Xmax at the lowest expected frequency that will be reproduced by the driver?

in this case, with 625 Watts of input, i reach the Xmax at 20 hz. since i will be high passing above that, is this safe? see attached...

Hi,

You will generally get mixed messages, from the clueless to the informed.

What you say above is correct, so there is not much more to add really.

Of course the more bass EQ you add the lower the average level it will
be able to handle, but it makes no difference to the maximum power
the said driver in its box can handle, just as much as EQ does not
change the max SPL a sealed box can produce at any frequency.

Heavy EQ, e.g. a +20dB LT gives you a huge upper bass surplus.

rgds, sreten.

[revboden]

wow... my laptop just freaked out... time to reload windows, sorry for the confusion.

listen to Sreten, he's right.

dang computer

[kipman725]

One reason I found to get a crazy powerfull amp in the UK even though I didn't rearly need it was that it just didn't cost much more. Apart from the fan noise the EP4000 is awsome

[sreten]

Hi,

The only thing I can add is that for music you don't get a single note.

I'd be quite happy using a 1KW amp for a max calculated 625W,
and at the lower end using 150W for a max calculated 50W given
its going to have a higher c/o point than the higher power case.

rgds, sreten.