OK ordered four Atlas12 and can't wait to install them in my pair of dipole cabinets.
Does anyone know how high in frequency these Atlas 12 can be used.
With the light cone and low Le, I would think they could be run up to 250 hz easily unless there is a cone breakup mode.
I will be using these Atlas 12 with a Fostex FX120 or Adire WR125s fullrange driver on an open baffle and would need to crossover in that range.
JM
Does anyone know how high in frequency these Atlas 12 can be used.
With the light cone and low Le, I would think they could be run up to 250 hz easily unless there is a cone breakup mode.
I will be using these Atlas 12 with a Fostex FX120 or Adire WR125s fullrange driver on an open baffle and would need to crossover in that range.
JM
Member
Joined 2003
The red line on the chart is the closest one to your situation, is the .52 qts in a very large 11.4cu foot sealed box. This is alignment has a box volume over 2.5 * vas, well on its way to infinite baffle, especially given the frequency. Be sure your cabinets dont act as transmission lines at these frequencies, it can lead to very lumpy response.
An externally hosted image should be here but it was not working when we last tested it.
I was just wondering if anyone has actually measured the response (not simulated) above 100 hz to know if there are cone resonances.
My dipole cabinets are half way between an H frame and U frame. The backs are heavily stuffed with fiberglass to hopefully damp resonances like Tweeker warned of.
I will post a pict when I get the drivers.
My plan is to use the dipole cabs from about 250 hz down to 50 hz and use a conventional sealed or vented box from 50hz and below.
I think Linkwitz also suggests this on his site.
I need to run the woofers up high enough to avoid stresssing the full range driver also planned for an open baffle.
JM
My dipole cabinets are half way between an H frame and U frame. The backs are heavily stuffed with fiberglass to hopefully damp resonances like Tweeker warned of.
I will post a pict when I get the drivers.
My plan is to use the dipole cabs from about 250 hz down to 50 hz and use a conventional sealed or vented box from 50hz and below.
I think Linkwitz also suggests this on his site.
I need to run the woofers up high enough to avoid stresssing the full range driver also planned for an open baffle.
JM
Well I got my four Atlas 12's and put a pair each into my 3 cf sealed boxes.
The walls of the boxes are lined with high density fiberglass glued on with silicone. The cavity is not stuffed. I hooked them up in parallel and drive them with my adcom amp. They are fed from an active crossover off my receiver's preouts. I cut them off at 90hz.
What I heard was muddy, one note bass. Very dissapointed. They are not nearly as good as single NHT 1259 for comparison. I also compared them to a pair of 10" audax drivers that were originally in the same cabinets and the Audax were cleaner and more musical, but did not have the xmax needed to play as loud.
I tried the different Q configurations which you can adjust with the second VC, but this did not clear up the 1-note sound. I also tried to load them aperiodically by drilling some small holes in the box, but no improvement. I also tried them in a dipole cabinet, but the 1 note sound persisted.
Maybe these drivers are better suited as a car subwoofer (thumper)? They are very attractive drivers and appear well made, but they seem to have a very stiff suspension to my manual prying.
I was hoping to use them up to 200hz but this would be out of the question from what I heard.
I hope that I can return these.
JM
The walls of the boxes are lined with high density fiberglass glued on with silicone. The cavity is not stuffed. I hooked them up in parallel and drive them with my adcom amp. They are fed from an active crossover off my receiver's preouts. I cut them off at 90hz.
What I heard was muddy, one note bass. Very dissapointed. They are not nearly as good as single NHT 1259 for comparison. I also compared them to a pair of 10" audax drivers that were originally in the same cabinets and the Audax were cleaner and more musical, but did not have the xmax needed to play as loud.
I tried the different Q configurations which you can adjust with the second VC, but this did not clear up the 1-note sound. I also tried to load them aperiodically by drilling some small holes in the box, but no improvement. I also tried them in a dipole cabinet, but the 1 note sound persisted.
Maybe these drivers are better suited as a car subwoofer (thumper)? They are very attractive drivers and appear well made, but they seem to have a very stiff suspension to my manual prying.
I was hoping to use them up to 200hz but this would be out of the question from what I heard.
I hope that I can return these.
JM
tiroth said:
Don't get me wrong, I don't know much about measuring specs...but shouldn't you measure any spec in the frequency range of the driver? 1kHz seems a bit high for a subwoofer. I would think that would affect the results a bit...though perhaps not enough to justify Ascendants measurements.
Personally, I'm not getting too bent out of shape, but there do seem to a number of problems with the T-S measurements. Others have pointed out that the change in parameters with the Qts adjustment don't seem to make sense. Le for instance is the same for all Qts settings, whereas I would have expected exactly the results I saw.
I think this is probably an honest mistake and not any attempt to mislead customers. Still, if there is a serious discrepency, it should be corrected.
I'm not certain of the usual test procedure for Le, although I thought it was often 1kHz and then a second factor at 10kHz. It does change with frequency. I'd certainly appreciate some independent confirmation of these measurements.
I think this is probably an honest mistake and not any attempt to mislead customers. Still, if there is a serious discrepency, it should be corrected.
I'm not certain of the usual test procedure for Le, although I thought it was often 1kHz and then a second factor at 10kHz. It does change with frequency. I'd certainly appreciate some independent confirmation of these measurements.
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