Hello All,
I have two of these now discontinued Peerless drivers. I'm not certain
that what I would like to do is a good idea with these woofers.
Background:
I'd like to build separate boxes for each of them and run them as "subs"
up to 150-Hz at 24 dB/oct upper cutoff. Box Qtc to be .5.
I have active crossovers and a dedicated "sub" amplifier. ( They can be
called "subs" or woofers for all I care, but there will be two of them.)
Active equalization is in the plan too, I will add about 6 to maybe 12 dB
of boost at the bottom, not an extreme amount, but enough to play
relatively flat to maybe 28 or 30 Hertz. Strictly music playback,
no movie stuff. This is my goal.
Problem:
The 830502/830514 drivers have Fs at about 40 Hz. Can a driver be
pushed to play in a region below its resonant frequency ?
I ask, because if these drivers will not meet my goal, I will sell them
and probably buy two Peerless 830452 which have a 19 Hz
resonant frequency.
What should I do ?
Thanks much for your advice/criticism/comments.
I have two of these now discontinued Peerless drivers. I'm not certain
that what I would like to do is a good idea with these woofers.
Background:
I'd like to build separate boxes for each of them and run them as "subs"
up to 150-Hz at 24 dB/oct upper cutoff. Box Qtc to be .5.
I have active crossovers and a dedicated "sub" amplifier. ( They can be
called "subs" or woofers for all I care, but there will be two of them.)
Active equalization is in the plan too, I will add about 6 to maybe 12 dB
of boost at the bottom, not an extreme amount, but enough to play
relatively flat to maybe 28 or 30 Hertz. Strictly music playback,
no movie stuff. This is my goal.
Problem:
The 830502/830514 drivers have Fs at about 40 Hz. Can a driver be
pushed to play in a region below its resonant frequency ?
I ask, because if these drivers will not meet my goal, I will sell them
and probably buy two Peerless 830452 which have a 19 Hz
resonant frequency.
What should I do ?
Thanks much for your advice/criticism/comments.
I remember considering this driver some years ago.
Nothing wrong with the driver in itself, you can probably eq it or (preferable) build a tp, th or t-tqwt type of enclosure and get it down to ~30hz.
Nothing wrong with the driver in itself, you can probably eq it or (preferable) build a tp, th or t-tqwt type of enclosure and get it down to ~30hz.
Last edited:
Hi, I liked your requirements despite 😱 the Car-TS-data for the drivers...
Here is a suggestion I think comes near:
First 150 Hz XO using a 24 dB/octave filter should be IMO relaxed to 145 Hz as a LR4 would then be 20 dB down at 250 Hz, thus would not 'push' down the phantoms towards the floor when listening to the subs placed close and summed to the mains.
When stuffed with damping material the FR slope will be smooth and gentle sloping like for a Qtc=0.5 closed box. Off-band ripple will be benign.
The suggested OD-TL have a sufficient wide BW and good phase/Gldy and the driver 'sees' an equivalent of Qt very near 0.5(If the terminus is closed).
The OD-TL must be stuffed and also used with a sub-amp providing a HPF at ~30HZ.
b🙂
Attachments
Thanks !
Bjorno, thank you for doing those calculations !
Specs are:
Fs = 39.4
Qms = 6.37
Qes = .42
Qts = .39
Vas = 21.4 liters
Xmax = +/- 12.5mm
I am more interested in the generic question of: Should a driver
be forced to play below its resonant frequency ? Ideally, I think NO.
Bjorno, thank you for doing those calculations !
Specs are:
Fs = 39.4
Qms = 6.37
Qes = .42
Qts = .39
Vas = 21.4 liters
Xmax = +/- 12.5mm
I am more interested in the generic question of: Should a driver
be forced to play below its resonant frequency ? Ideally, I think NO.
Thanks!
Forced? IME the driver couldn't care less. My understanding is what it wants to 'feel' is a matching acoustical impedance on both sides of its diaphragm in its resonant BW, ergo either an OB or its reciprocal, a compression horn [or at least a band-pass alignment]; so with these specs it has a theoretical box tuning range from its Fl = Fs*Qts/2 = ~7.68 Hz to its Fh = Fs*2/Qts = ~202.5 Hz.
Of course power handling normally sets the practical lower limit and in this driver's case it can in theory be safely tuned all the way down to Fl at up to 300 W in half space, so size and build complexity is its limiting factors.
GM
Forced? IME the driver couldn't care less. My understanding is what it wants to 'feel' is a matching acoustical impedance on both sides of its diaphragm in its resonant BW, ergo either an OB or its reciprocal, a compression horn [or at least a band-pass alignment]; so with these specs it has a theoretical box tuning range from its Fl = Fs*Qts/2 = ~7.68 Hz to its Fh = Fs*2/Qts = ~202.5 Hz.
Of course power handling normally sets the practical lower limit and in this driver's case it can in theory be safely tuned all the way down to Fl at up to 300 W in half space, so size and build complexity is its limiting factors.
GM
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