I've seen some posts regarding this old design but they got no response. Basically this is a sealed box sub with the driver coupled to the air through a resistive aperture into a wide slot. Supposedly went flat down to 30Hz ! Something like a Ripole sub. In a Ripole the slot /driver interface has the driver diameter as the interface. Here this is blocked and only a small opening used to connect the two. The rear being sealed off unlike a Ripole. That cuts off the out of phase rear radiation. So the loading on the front helps to extend the LF as compared to regular cabinets.
The slot area is about 1/3rd the cone area . How is a slot loading simulated ? Like a box with volume of the slot and very short duct with area equal to the mouth of the duct ? Can slot loading be simulated in Horn Response ? Slot loading behaving slightly different from a regular duct !?
Has anyone actually made something similar to a Janis sub ? Maybe Rudolf can try this on one of his Ripoles ? 🙂
The slot area is about 1/3rd the cone area . How is a slot loading simulated ? Like a box with volume of the slot and very short duct with area equal to the mouth of the duct ? Can slot loading be simulated in Horn Response ? Slot loading behaving slightly different from a regular duct !?
Has anyone actually made something similar to a Janis sub ? Maybe Rudolf can try this on one of his Ripoles ? 🙂
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Sounds almost like a 4th order band pass. Easy enough to sim in Hornresp, though I doubt it'll be flat to 30Hz.
Chris
Chris
One of the advantage of 4th bandpass is limited excursion so that well designed you don't need any high pass for it.
Another is that front chamber can act as a low pass, and being acoutic low pass, it low pass harmonics too, and so reduce a lot high order harmonics.
Disavantage should be non linearity if using too small back chamber, and chuffing effect of port.
Without front chamber, you have to deal with some resonance...Here my simple 12" woofer 30L bandpass project with/without 10L front chamber. 50cm²/20cm long output port. (i don't feel the need of going lower to excite home resonnances/ It will be dsp eq ).
Another is that front chamber can act as a low pass, and being acoutic low pass, it low pass harmonics too, and so reduce a lot high order harmonics.
Disavantage should be non linearity if using too small back chamber, and chuffing effect of port.
Without front chamber, you have to deal with some resonance...Here my simple 12" woofer 30L bandpass project with/without 10L front chamber. 50cm²/20cm long output port. (i don't feel the need of going lower to excite home resonnances/ It will be dsp eq ).
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Here is the basic structure of the speaker. The original woofer came in for a lot of flak for 'looking' cheap ! They said small magnet ! From that, one might infer that it might have a high Qts. The driver also seemed to be covered with what looked like a muslin like 'cloth' cover all around the rear of the chassis. An old way of altering the acoustic resistance and altering the Q. Could only see the rear in the picture . No one has a picture of the driver outside the box. Access appears to have been only from the rear. Even the exit of the slot is covered with a sheet with a slot perforation pattern on it. I'll look for the pictures again.
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Hi ashok,
Post #1: "... Can slot loading be simulated in Horn Response ?..."
Looking at the sketch in post #4 it should be simulated as a front loaded horn, using "Driver Arrangement' Nd. The rear chamber is Vrc/Lrc, the front chamber Vtc/Atc, the coupling to the slot is Ap1/Lp, the slot goes from there as S1 to how ever many segments you want to use so that you can define a final segment for the perforated terminus.
Regards,
Post #1: "... Can slot loading be simulated in Horn Response ?..."
Looking at the sketch in post #4 it should be simulated as a front loaded horn, using "Driver Arrangement' Nd. The rear chamber is Vrc/Lrc, the front chamber Vtc/Atc, the coupling to the slot is Ap1/Lp, the slot goes from there as S1 to how ever many segments you want to use so that you can define a final segment for the perforated terminus.
Regards,
Thanks Oliver. I think I'll try this. Looks like an interesting experiment. I have unused drivers too !
Yes. Now that you mention it, With all that fill , it will require something to keep it away from the innards of the driver.
However several years ago I have used the method to alter the drivers performance in a box. Don't remember if I got what I wanted. It's too long ago.
I bought a W-1 and amp around 1987 for little money and proceeded to build 2 more after purchacing 2 15" woofers from John M. when money was tight back then.
The stamped frame woofer uses an accordian non rubber surround suspension with the hemholtz approach. At least it won,t rot away and as a system does have low distortion down low. I use 2 in my video system ( 23'x27' 12' peak ceiling point) and have measured flat to 23 hz. The woofer is flat to 30 hz and room gain gets me to 23 hz.
The motor works and the stamped basket look means nothing here..
Its not in the high spl leagues of modern subs but decent enough.
High order cross over is necessary since there were peaks in the tunnel ( that I measured) around 400hz as I remember , that added a signature to its sound easily cured with higher orders. This was reviewed and a known issue.
I have tried 100/150 Krell clones PSE mk V all mono blocks and only average perfomance!
The one amp that totally transformed and blew these away was a simple Parasound hca1000a on these subs
Just a remarkable difference and combination!
I think the reason for this is these subs need an amp with tight DC offset and John M. had an adjustment on his amp to compensate as I recall.
My cloned 150 has the dc servo with discreet trans. but doesn,t sound as tight as the Parasound that uses an ic based servo.
I have pics somewhere when I made the 2 and will post
Made with Koa veener all around
Regards
David
The stamped frame woofer uses an accordian non rubber surround suspension with the hemholtz approach. At least it won,t rot away and as a system does have low distortion down low. I use 2 in my video system ( 23'x27' 12' peak ceiling point) and have measured flat to 23 hz. The woofer is flat to 30 hz and room gain gets me to 23 hz.
The motor works and the stamped basket look means nothing here..
Its not in the high spl leagues of modern subs but decent enough.
High order cross over is necessary since there were peaks in the tunnel ( that I measured) around 400hz as I remember , that added a signature to its sound easily cured with higher orders. This was reviewed and a known issue.
I have tried 100/150 Krell clones PSE mk V all mono blocks and only average perfomance!
The one amp that totally transformed and blew these away was a simple Parasound hca1000a on these subs
Just a remarkable difference and combination!
I think the reason for this is these subs need an amp with tight DC offset and John M. had an adjustment on his amp to compensate as I recall.
My cloned 150 has the dc servo with discreet trans. but doesn,t sound as tight as the Parasound that uses an ic based servo.
I have pics somewhere when I made the 2 and will post
Made with Koa veener all around
Regards
David
I have two Janis W1 woofers. They are used with a 24 db per octave active crossover.
I am thinking of updating the drivers. Reason being that I think after 30 years there are improvements to driver design. The only problem is that I am not sure what T/S parameters are the ones to concentrate on to provide a good match to the enclosure. I was thinking of something with a higher BxL factor for a tighter bass.
Any thoughts?
I am thinking of updating the drivers. Reason being that I think after 30 years there are improvements to driver design. The only problem is that I am not sure what T/S parameters are the ones to concentrate on to provide a good match to the enclosure. I was thinking of something with a higher BxL factor for a tighter bass.
Any thoughts?
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