which subwoofer for 250W@4ohms class D amp ? - diyAudio
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Old 12th July 2012, 09:34 AM   #1
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Lightbulb "SOLVED" : 38cm subwoofer for only 250W@4ohms amp

[ this first message have been edited twice :
1/ Considering the following answers (thanks a lot for your help !!! )
2/ when I've made my decision]

I begin to built my home-project with the sub-woofers, using a 2x250W@4ohms Tripath amp.
I don't care of the upper cut frequency : I would choose the "(grave)medium" after.
Of course, the smaller, the better... But it's not the main problem for me up to 150L (why not bigger, if it is worth).

Less than 300€ for one speaker, and down to 30Hz would be nice.
As I will use an equalizer, "down to 30 Hz" doesn't mean -3db but just the max SPL between 30 & 40Hz with 250W@4ohms !
[As 250W is quite small, it means max sensitivity between 30-40Hz for all the loudspeakers too.]
>>>>>> false !!!!!! Xmax is important too, even with only 250W

Here is a table of values for (Bessel) Bass Reflex. Don't know if 4th order pass band or TQWL or ... would be better for this.

Click the image to open in full size.

Finally, even if my thougts about sensibility was quite false, I have chosen two SPH390TC
(even if it's a steel, no ventilated basket and needs an quite important volume for Bessel BR...)
...because I hope to use experience of others !

Last edited by FroggySeven; 17th July 2012 at 07:49 PM. Reason: SOLVED (decision made at least...)
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Old 13th July 2012, 12:09 AM   #2
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Do you mean 30Hz -3dB's/F3 or other. Is that car or home?
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Old 13th July 2012, 08:06 PM   #3
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Thank you to try to help me.

It's for home, so no problem up to 150L (but the smaller, the better...and why not bigger if it is worth)

As I would use a egalizer, I just want the max SPL with 250W at 30Hz
(as 250W is quite small, means the max sensitivity at 30Hz. Is 90db/1W/1m possible ???)
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Old 13th July 2012, 08:56 PM   #4
zuki is offline zuki  United States
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this woofer was 99.00 yesterday.
but no longer a good deal.
Dayton Audio DVC310-88 12" DVC Series Subwoofer 295-185
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Old 13th July 2012, 08:56 PM   #5
tb46 is offline tb46  United States
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Hi FroggySeven,

How about a tapped horn using the B&C 10NW64, it should be fine from 30Hz to 120Hz (this is simulation only, no enclosure design)? Guessing, it would be about 125 L external volume.

Regards,
Attached Images
File Type: jpg B&C_10NW64_Input.jpg (36.4 KB, 262 views)
File Type: jpg B&C_10NW64_SPL.jpg (29.7 KB, 257 views)
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Old 14th July 2012, 12:23 AM   #6
Djim is offline Djim  Netherlands
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Hi Oliver,

Maybe you should check the acoustic pressure below 40Hz (the Fs of the B&C is above 1/2 wavelength).
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Old 14th July 2012, 01:35 AM   #7
tb46 is offline tb46  United States
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Hi Djim,

I think it is within reason :-) ; see e.g.: the attached Hornresp plots for the B&C 10Nw64 and the Eminence 3015LF in the SS15. I know you don't like to see the Fs that high versus the lower end of the bandpass, but all the inital work on tapped horns seemed to indicate, that there is nothing wrong with designing a TH that way. FroggySeven has set some difficult parameters: 30Hz-3dB / 90dB/1W/1m / <150L / <300Euro / 250W, maybe you have a better suggestion.

Regards,
Attached Images
File Type: jpg B&C_10NW64_Throat Pressure_at_Xmax.jpg (31.0 KB, 234 views)
File Type: jpg Eminence_3015LF_Throat Pressure_at_Xmax.jpg (29.3 KB, 227 views)
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Old 14th July 2012, 03:02 AM   #8
Djim is offline Djim  Netherlands
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Hi Oliver,

What I like is not important :-). All I can see is the predicted response and predicted max output for the SS15 are both not reached in real measurements ;-).

I agree that FroggySeven has set out parameters that are difficult. 150 litres and 90dB at 30 Hertz. It can be reached with a dual 12” setting in a basreflex (maybe in a PPSL setting). Look for 12” drivers with an Fs of 25-30Hz, enough sensitivity down low and a motor/suspension that can handle 75 litres per driver with 30-34Hz tuning. For instance the old Pioneer (Premier in US) TS-W12 can do such job.
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Old 14th July 2012, 03:21 PM   #9
tb46 is offline tb46  United States
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Hi Djim,

"...the old Pioneer (Premier in US) TS-W12 can do such job."

So can two JBl GTO1214, maybe as a PPSL.

Regards,
Attached Images
File Type: jpg BR_JBL_GTO1214_Dual_Input.jpg (36.7 KB, 37 views)
File Type: jpg BR_JBL_GTO1214_Dual_SPL.jpg (27.2 KB, 28 views)
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Old 15th July 2012, 01:24 AM   #10
Djim is offline Djim  Netherlands
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Quote:
Originally Posted by tb46 View Post
So can two JBl GTO1214
Sure they can :-)

Click the image to open in full size.
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