Learned diyers.
I must have too much time on my hands reading threads here.
I would like to have a go at a subwoofer. Never attempted anything of this nature before.
I just happen to have 2x b139 passive radiators from a pair of 104's and a b139 sp1044 8ohm from a pair of TL's.
Looking at a sealed enclosure 60x40x70 cm mounting the passives horizontally opposed in the sides and the sp1044 in front.
Using a low pass 12db filter with L of 9mh and two 40uf caps in parallel to cross at app 200 Hz. Could this get down to 25hz?
Could this work or be a total waste of time?
I must have too much time on my hands reading threads here.
I would like to have a go at a subwoofer. Never attempted anything of this nature before.
I just happen to have 2x b139 passive radiators from a pair of 104's and a b139 sp1044 8ohm from a pair of TL's.
Looking at a sealed enclosure 60x40x70 cm mounting the passives horizontally opposed in the sides and the sp1044 in front.
Using a low pass 12db filter with L of 9mh and two 40uf caps in parallel to cross at app 200 Hz. Could this get down to 25hz?
Could this work or be a total waste of time?
Passive crossovers, especially that size 9mh, are going to add all kinds of distortion phase problems ringing into the audio, a high quality active crossover is better, plus you get volume control, bass boost of the low frequencies such as 30 hz, cleaner sound, phase control, ability to input from balanced, unbalanced, speakon. A 9mh is going to add a lot of " impedance " into the circuit.
Thanks for your reply Chris.
I have diy Altec 511b horns (well tamed) and 12" woofer great sounding efficient system . Amp is 300w Holton ss all made by one diy'er used for stereo hifi only.
I also have gale 401, Osborn eclipse and an Osborn plate amp sub for theatre in another room.
I put this proposal together from info here on diyaudio.
I happen to have the drivers wanted to experiment. I do not know anything of active xo's I imagine expensive.
Cheers David
I have diy Altec 511b horns (well tamed) and 12" woofer great sounding efficient system . Amp is 300w Holton ss all made by one diy'er used for stereo hifi only.
I also have gale 401, Osborn eclipse and an Osborn plate amp sub for theatre in another room.
I put this proposal together from info here on diyaudio.
I happen to have the drivers wanted to experiment. I do not know anything of active xo's I imagine expensive.
Cheers David
I was curious about the driver.
Seems to be a few versions from the 80's to 90's
I just wanted to get a basic model into WinIsd
Using the small signal parameters, and overall SD to get a general idea
of how the driver performs mechanically.
And to be able to answer the Question if 25 Hz was feasible.
I cannot model the passive drivers, because I was unable to find
the parameters.
But using a normal vented/reflex style box
And just Checking a fairly common 3rd order
Butterworth filter alignment or Quasi Butterworth (QB3)
SP1044 Driver QB3 Alignment = 2.62 Cubic Feet (74.2 Liters) 24 Hz tuning
Seems to have a F3 response of 24.7 Hz
So within reason, yes the driver can Achieve 25 Hz
As far as if possible with 2 passive radiators.
It is likely to be close. But couldn't be confirmed or fine
tuned without knowing the radiators specifications.
Ideally the rule of thumb is to have at least double the radiator
area than the driver. Which you do have.
And likely your ideal radiator tuning would be similar around 23/25 Hz
With a overall volume similar to the reflex alignment 2.6 to 3 cubic feet
Seems to be a few versions from the 80's to 90's
I just wanted to get a basic model into WinIsd
Using the small signal parameters, and overall SD to get a general idea
of how the driver performs mechanically.
And to be able to answer the Question if 25 Hz was feasible.
I cannot model the passive drivers, because I was unable to find
the parameters.
But using a normal vented/reflex style box
And just Checking a fairly common 3rd order
Butterworth filter alignment or Quasi Butterworth (QB3)
SP1044 Driver QB3 Alignment = 2.62 Cubic Feet (74.2 Liters) 24 Hz tuning
Seems to have a F3 response of 24.7 Hz
So within reason, yes the driver can Achieve 25 Hz
As far as if possible with 2 passive radiators.
It is likely to be close. But couldn't be confirmed or fine
tuned without knowing the radiators specifications.
Ideally the rule of thumb is to have at least double the radiator
area than the driver. Which you do have.
And likely your ideal radiator tuning would be similar around 23/25 Hz
With a overall volume similar to the reflex alignment 2.6 to 3 cubic feet
