i was not sure if this should be in the amp or sub section, so moderators, please move if this is incorrect.
i'm working on my first DIY sub project and have arrived at a few nice options - if WinISD is representative of response in my room. regarding appropriate amplification power - in determining how much power to look for in an amp, i am using the 'System Input Power' field in the 'Signal' tab and adjusting until i am just under the Xmax on the 'Cone Excursion' graph.
i am actually surprised at how little power i can use before exceeding the drivers Xmax... in a few scenarios it's far less than the rated power handling of the driver - as low as 150 Watts.
i commonly read about 1kW amps used in subs, so am wondering if i'm going at this the wrong way and misinterpreting what WinISD is indicating.
any advice on using WinISD to determine the correct amp output would be appreciated.
i'm working on my first DIY sub project and have arrived at a few nice options - if WinISD is representative of response in my room. regarding appropriate amplification power - in determining how much power to look for in an amp, i am using the 'System Input Power' field in the 'Signal' tab and adjusting until i am just under the Xmax on the 'Cone Excursion' graph.
i am actually surprised at how little power i can use before exceeding the drivers Xmax... in a few scenarios it's far less than the rated power handling of the driver - as low as 150 Watts.
i commonly read about 1kW amps used in subs, so am wondering if i'm going at this the wrong way and misinterpreting what WinISD is indicating.
any advice on using WinISD to determine the correct amp output would be appreciated.
What kind of sub are you building, ported, sealed etc. ? It sounds like you are doing it right (WINisd).
Hi,
In WinISDpro you will quickly realise for a 1KW sub you need to choose the
bass driver very carefully and probably need to apply loads of bass boost
to get the thermal limit near the excursion limit at low frequencies.
You can EQ a driver with fixed volume displacement, excursion x cone area
to any frequency response you like. Given that, the frequency response in
box only determines how much power you need for the EQ, you make the
box smaller, you need more power for the same response, so you can
trade off reducing box size up to the power handling limit of the driver.
Unfortunately I don't think WinISDpro takes into account any bass boost
actively applied in most graphs, only the frequency response / excursion.
rgds, sreten.
In WinISDpro you will quickly realise for a 1KW sub you need to choose the
bass driver very carefully and probably need to apply loads of bass boost
to get the thermal limit near the excursion limit at low frequencies.
You can EQ a driver with fixed volume displacement, excursion x cone area
to any frequency response you like. Given that, the frequency response in
box only determines how much power you need for the EQ, you make the
box smaller, you need more power for the same response, so you can
trade off reducing box size up to the power handling limit of the driver.
Unfortunately I don't think WinISDpro takes into account any bass boost
actively applied in most graphs, only the frequency response / excursion.
rgds, sreten.
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two small sealed subs... either a single down firing 10" driver (TC Sounds Epic 10 or Acoustic Elegance AV10H if they become available) in a 14.5 L (0.51 ft3) enclosure or dual opposed side firing 8" drivers (TC Epic 8 or Funky Waves 8) in a 16.2 L (0.57 ft3) enclosure. those enclosure volumes are my best estimate at internal volumes.
even with the relatively large Xmax specs for these drivers, the max input i can use before exceeding the Xmax on the Epic 10 is 280 Watts and on the dual 8's it's 350 Watts. i was pretty surprised at these results.
even with the relatively large Xmax specs for these drivers, the max input i can use before exceeding the Xmax on the Epic 10 is 280 Watts and on the dual 8's it's 350 Watts. i was pretty surprised at these results.
Hi, so make them smaller and EQ, you will get higher power handling, but no more SPL, rgds, sreten.
here's a screen shot showing the Cone Excursion, Eq and Input Power for the TC Epic 10. any more than 280 Watts, and I'm well past the Xmax. If i remove the Linkwitz Transform, i can use more power... trade-offs!
Does this mean I should not buy an amp that puts out more that 280 Watts? If yes, if the QSC RMX 850 a nice option?
-Scott
Does this mean I should not buy an amp that puts out more that 280 Watts? If yes, if the QSC RMX 850 a nice option?
-Scott
Attachments
I'll model them and see if I get the same results. But they sound right, 280-350w is a lot of power.
I tried to upload the WinISD file i'm using for this particular driver but the file type is not supported.
Hi,
I don't think WinIsDpro models this properly, for a given box and driver
max power for the excursion limit is independent of any EQ applied.
So choose box size for amp power needed for max SPL standard sealed,
and then ignore the subsequent results for EQ, they are wrong AFAICT.
rgds, sreten.
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i see the peak of 340W at 33 hz... since i can only input 280 W prior to exceeding the Xmax, does this mean that for this configuration, if i stay with 280 W so as not to exceed the excursion limit, there will be diminished output at 33 hz?
the dual TC Sounds Epic 8 build does not have this issue - i can use a 350 Watt amp without exceeding the Xmax, and the peak amplifier apparent load is 200 Watts.
The 280w is the power used to get the levels at frequencies above the LT circuit, as the LT starts to boost the line level signal, 340w is the power needed to exceed Xmax at 33Hz.
Hi Sreten, sorry if i communicated this poorly - the Xmax does not change, but the amount of cone excursion goes up when a Linkwitz Transform is applied. If I do not use the LT, I can use more power prior to exceeding the Xmax. Attached are the excursion graphs with and without the Linkwitz Transform.
Attachments
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Hi,
No. WinISDpro is wrong, it applies the extra excursion of the EQ as though
its extra efficiency of the driver in box, hence lowering the power needed,
its simply wrong, it does not happen, they haven't properly modelled it.
Model a standard sealed box for power needed for max SPL, ignore using EQ.
Then add any EQ you like, max SPL/Power for sealed is independent of any EQ.
rgds, sreten.
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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!
the parameters i have for the TC Sounds drivers are a little different than what is posted on their product specs... Attached find the specs the company sent me directly (when i mentioned the disparity, they said these figures were more representative).
Attachments
I just modeled the LT manually and get 280w with LT to reach Xmax with the TC10. Sreten is right WinISD does not model LT boost correctly.
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that is what WinISD shows, too... with LT, 280 Watts pushes the driver right to the Xmax. the attached image shows the cone excursion with LT and 280 Watts.
if you did the LT manually (how did you do that??) and got the same results, what in WinISD is incorrect - or what am i completely missing here?
Attachments
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