Probably not a good idea to tune a PR to 17Hz. Even if the box volume permits it.
You want to run a simulator program (as if it was a ported box) given the volume of the box AND the T/S parameters of the speaker, see where the F3 point comes out in Hz. Set the response for a "butterworth". You can tune the PR to that frequency, and certainly less than a 1/2 octave below that and get a useful response... At 1/2 octave below that there will likely be a large dip between the PR output and the driver...
The other consideration is that the mass that has to be added, which will be considerable, may be excessive and cause the suspension to be distorted or come apart... also a vertical mounting is required.
So, assuming you get 40Hz. you could tune the passive to maybe 32Hz. and have a nice sounding speaker. Remember the tuning point is the *center point* and the PR works somewhat above and below that frequency.
PS. I don't know a thing about this CSS company or their products
You want to run a simulator program (as if it was a ported box) given the volume of the box AND the T/S parameters of the speaker, see where the F3 point comes out in Hz. Set the response for a "butterworth". You can tune the PR to that frequency, and certainly less than a 1/2 octave below that and get a useful response... At 1/2 octave below that there will likely be a large dip between the PR output and the driver...
The other consideration is that the mass that has to be added, which will be considerable, may be excessive and cause the suspension to be distorted or come apart... also a vertical mounting is required.
So, assuming you get 40Hz. you could tune the passive to maybe 32Hz. and have a nice sounding speaker. Remember the tuning point is the *center point* and the PR works somewhat above and below that frequency.
PS. I don't know a thing about this CSS company or their products
That really depends on the driver and the PR. The CSS APR15 has an Fs of 19 and can be tuned to 17 in a ~110 liter box w/o excessive mass. AE 15" PRs have Fs of 6 and can also be tuned very low if desired.
In combination w/ a Vifa NE315W, for instance, the CSS APR15 works wonderfully tuned to 24Hz in 57 liters. Around 630 grams mass needed.
1200 is the limit for the APR15.
Inherent in the nature of the PR is a dip at the resonant frequency, not somewhere else.
Your advice is . . . ?
In combination w/ a Vifa NE315W, for instance, the CSS APR15 works wonderfully tuned to 24Hz in 57 liters. Around 630 grams mass needed.
1200 is the limit for the APR15.
Inherent in the nature of the PR is a dip at the resonant frequency, not somewhere else.
Your advice is . . . ?
If you can tell me what sub drvire you are using and how big the box is, I can give you a rough idea of the weight.
Wha? Fs of 6Hz???
What is that for??
How is it used?
The "dip" is not in the PR output, but in the motion of the main driver. The PR output is MAX at the resonant frequency.
One gets a dip in freq response between the driver and the PR when the PR is tuned sufficiently below the F3 point of the driver + box.
I am unaware of an standard production woofer that can tune to 6Hz. or match/hand off to a PR at 6 Hz. Certainly not in a box volume that is practical...
...the lowest one can get a woofer to operate at is in an IB where Fs = F3 but then you can't use a PR.
Maybe there is something going on I haven't heard of, if so I'd like to know what it is.
_-_-bear
PS. if the stock PR has an Fs of 19Hz. it may not make any difference or have any benefit to move it to 17Hz. Probably not audible.
What is that for??
How is it used?
The "dip" is not in the PR output, but in the motion of the main driver. The PR output is MAX at the resonant frequency.
One gets a dip in freq response between the driver and the PR when the PR is tuned sufficiently below the F3 point of the driver + box.
I am unaware of an standard production woofer that can tune to 6Hz. or match/hand off to a PR at 6 Hz. Certainly not in a box volume that is practical...
...the lowest one can get a woofer to operate at is in an IB where Fs = F3 but then you can't use a PR.
Maybe there is something going on I haven't heard of, if so I'd like to know what it is.
_-_-bear
PS. if the stock PR has an Fs of 19Hz. it may not make any difference or have any benefit to move it to 17Hz. Probably not audible.
You need 13 washers (585gm) voice coils in parallel. However, that's a terrible alignment for the Shiva. You get much better response (F3/F10: 24.2 / 19.4) by tuning to 21.4Hz: 7 washers / 315 gms.
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