Fiat79, what did you end up doing with those 45's?
I have four, so I welded up some aluminum "C" channel to base plates, and made 2 nice floor-to-ceiling line sources good for 1000 hz up. The floor and ceiling reflections make a 'virtual line source of infinite height and depth" with no filter effects resulting from the ends of the line sources.
I also bought six of the boxes John uses in the R645 with 2 scan-speak mid-bass drivers in each. I bolted together 2 sets of 3 boxes each, making two vertical stacks with 6 drivers in each. I wanted them to go lower, so I sealed up the ports and added EQ. Still really needs subs, but I'm currently broke. So I'm contemplating perhaps adding 6 more drivers, so each box would have 3 instead of 2. That would make the box volume per driver less, but offer more cone area and power handling. I haven't done the math. But it might meet my needs for a while with my current amps and active crossover.
I have four, so I welded up some aluminum "C" channel to base plates, and made 2 nice floor-to-ceiling line sources good for 1000 hz up. The floor and ceiling reflections make a 'virtual line source of infinite height and depth" with no filter effects resulting from the ends of the line sources.
I also bought six of the boxes John uses in the R645 with 2 scan-speak mid-bass drivers in each. I bolted together 2 sets of 3 boxes each, making two vertical stacks with 6 drivers in each. I wanted them to go lower, so I sealed up the ports and added EQ. Still really needs subs, but I'm currently broke. So I'm contemplating perhaps adding 6 more drivers, so each box would have 3 instead of 2. That would make the box volume per driver less, but offer more cone area and power handling. I haven't done the math. But it might meet my needs for a while with my current amps and active crossover.
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Since I made mine, Newform built something similar (better) with the planar-dynamic line sources mounted in front of the mid-bass driver tower. But mine I usually have to the side. I really should try mine in front of the mid-bass stack, especially since the Rane active crossover I use has time delays available, so I should be able to correct for the slight forward offset from the mid-bass drivers. The Rane's built-in delay section is usually applied to the low-frequency sections to time-align longer horns and folded horns in PA applications, but the delay section can by used on the high-frequency section instead via internal jumpers. I assume it's an analog bucket-brigade filter line type of delay, so it might not really perform as well on the high-frequency section, but its performance is probably better for only a short delay.
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Cyclecamper,
If I remember correctly, I don't think JM thought the original shape of the R45 was that far off when used as a coaxial ribbon. One could always add part of a half round to the back of the R45 to reduce defraction. Also, somewhere in the Newform literature there is mention of the delay time that JM uses.
You may already know this, JM was using 12dB Butterworth at 957 Hz and the ribbon was rolled in with a 6 dB Butterworth at 2.11kHz on the R645. From JM, "The acoustic crossover is effectively around 1 kHz." His settings may have changed and I'm sure he would be more than happy to assist you, as he's been very generous in assisting me.
Good luck and have fun.
CraigJ
If I remember correctly, I don't think JM thought the original shape of the R45 was that far off when used as a coaxial ribbon. One could always add part of a half round to the back of the R45 to reduce defraction. Also, somewhere in the Newform literature there is mention of the delay time that JM uses.
You may already know this, JM was using 12dB Butterworth at 957 Hz and the ribbon was rolled in with a 6 dB Butterworth at 2.11kHz on the R645. From JM, "The acoustic crossover is effectively around 1 kHz." His settings may have changed and I'm sure he would be more than happy to assist you, as he's been very generous in assisting me.
Good luck and have fun.
CraigJ
I change the crossover fequency based on volume and what else I'm using the "ribbons" with. I used to have 4 mid-bass boxes with 8 6.5" drivers in each, which I used ocassionaly (otherwise I played bass guitar thru them). But they've been sold. As a 2-way I cross over around 1K. As a 3-way with a sub I cross the ribbons around 2K.
Anyone want to venture a guess about how the Newform cabinets (bought as factory blems) would perform (sealed) with 3 18W/8545-00 scan-speak mid-bass drivers in each instead of just 2? I expect to use EQ.
While an uncomplicated 2-way sounds attractive in its simplicity, I think I'd better get a job and buy some subs. It would also be very convenient since the Rane is stereo 3-way and plenty of channels of power ampification.
Anyone want to venture a guess about how the Newform cabinets (bought as factory blems) would perform (sealed) with 3 18W/8545-00 scan-speak mid-bass drivers in each instead of just 2? I expect to use EQ.
While an uncomplicated 2-way sounds attractive in its simplicity, I think I'd better get a job and buy some subs. It would also be very convenient since the Rane is stereo 3-way and plenty of channels of power ampification.
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