Did You build a prototype?
Did you build a prototype and see what it sounded like with the
451 driver in it?
RCF now has the 551 version out with longer Xmax.
Of course it costs more and requires more power (slightly less efficient)
but will handle more power (ie: LabGruppen 10000Q or 20000Q).
Another driver that shows promise ($$$ wise) is the Celestion NTR21-5010JD.
Less Xmax, but almost half the cost of the RCF on Amazon.
Did you build a prototype and see what it sounded like with the
451 driver in it?
RCF now has the 551 version out with longer Xmax.
Of course it costs more and requires more power (slightly less efficient)
but will handle more power (ie: LabGruppen 10000Q or 20000Q).
Another driver that shows promise ($$$ wise) is the Celestion NTR21-5010JD.
Less Xmax, but almost half the cost of the RCF on Amazon.
hi there
sad to say it's never been bild.
the 551 sims good in the same cab.
regards erik
if it works well...............
I believe this is an arrayable solution to my problem. My problem is my line array is a quite serious box with high output (RCF TTL-55). Finding a sub to ground stack and keep up with it (30-120hz, worst case "driven really hard" scenario) is a task.
I had LABsubs that worked quite well in that passband, but went to a permanent install last year;(.
Time for a new design.
Can't do the RCF TTL-56 boxes. Can't utilize my existing amps and they're too much $$$$$ relative to what I can build.
If I can build 16 Labsubs, I can build 16 of these. The Unisaw calls...........
Plus we have a resource for 18mm 13ply locally.
Attached is my "final"? drawing or the build.
I believe this is an arrayable solution to my problem. My problem is my line array is a quite serious box with high output (RCF TTL-55). Finding a sub to ground stack and keep up with it (30-120hz, worst case "driven really hard" scenario) is a task.
I had LABsubs that worked quite well in that passband, but went to a permanent install last year;(.
Time for a new design.
Can't do the RCF TTL-56 boxes. Can't utilize my existing amps and they're too much $$$$$ relative to what I can build.
If I can build 16 Labsubs, I can build 16 of these. The Unisaw calls...........
Plus we have a resource for 18mm 13ply locally.
Attached is my "final"? drawing or the build.
Attachments
It will be a Spring project, I'm thinking.
As long as these trucks hold up.............
Only problem I had with the LABs was pole-piece heat and power compression
at EDM shows where the duty cycle got near 50%. It didn't help the amount of compression/limiting we had to run to minimize excursion damage on those drivers.
These 21" drivers seem to minimize those issues and this cab design has the magnet structure out there in the open air so they can radiate that heat.
I'll keep everybody posted on the results.
Thanks ever so much.
As long as these trucks hold up.............
Only problem I had with the LABs was pole-piece heat and power compression
at EDM shows where the duty cycle got near 50%. It didn't help the amount of compression/limiting we had to run to minimize excursion damage on those drivers.
These 21" drivers seem to minimize those issues and this cab design has the magnet structure out there in the open air so they can radiate that heat.
I'll keep everybody posted on the results.
Thanks ever so much.
final
I think I'm to a point I can do a prototype in MDF from this drawing. Had to pull/push today to keep the "M" (expansion coefficient) constant in the radius areas. It "looks" right anyway. Sorry for the Imperial dimensions. That kind of dates me and where I'm from. I'd be metric too if everything here was converted. Spring time before I can hit stride with this. Quite busy with the case building right now. 
Thanks Midas M-32...............
I think I'm to a point I can do a prototype in MDF from this drawing. Had to pull/push today to keep the "M" (expansion coefficient) constant in the radius areas. It "looks" right anyway. Sorry for the Imperial dimensions. That kind of dates me and where I'm from.
I'd be metric too if everything here was converted. Spring time before I can hit stride with this. Quite busy with the case building right now. Thanks Midas M-32...............Attachments
Just stumbled on this thread. Very cool - great work and super generous contribution from Epa here. Looking forward to seeing it realized. What does 2.5 sheets of 18mm BB and the driver weigh? Also it is not clear is the final selected driver still the 21in RCF or is B&C 21 getting selected?
heavy..........
The sheets of 18mm baltic birch weigh 75# each. It will take just under 2.5 sheets per box depending on the bracing and how crazy you get with that since those can be the odd shaped parts. The box itself will weigh about 230#. Driver selection will add from that. The construction has to be air tight so 13ply is the most stable/dimensionally consistent material you can find. Use the Russian stuff, it has waterproof glue and takes a deck screw extremely well. The screws have to pull the panels flush and that takes a LOT of force.
All the Italian Neo drivers are pretty similar in weight/cone composition/and BL factor.
The price spread depends on the relationship with your supplier. These things are not flying off the shelves since 18's have ruled the market for so long and are still getting the job done.
The criterion for MY driver selection is:
over-excursion forgiveness (LabGruppen 20000Q's take few/no prisoners)
*sensitivity/power handling trade-off
*weight
*dealer support of the product
*price
The four top driver contenders for me are:
B&C 21SW152
RCF LF21N451
RCF LF21N551
18Sound 21NLW9600
they range in price from 600 to 900 bucks each.
So in theory, this box can be built using sweat equity for less than $1,000.00 each if you're resourceful.
The sheets of 18mm baltic birch weigh 75# each. It will take just under 2.5 sheets per box depending on the bracing and how crazy you get with that since those can be the odd shaped parts. The box itself will weigh about 230#. Driver selection will add from that. The construction has to be air tight so 13ply is the most stable/dimensionally consistent material you can find. Use the Russian stuff, it has waterproof glue and takes a deck screw extremely well. The screws have to pull the panels flush and that takes a LOT of force.
All the Italian Neo drivers are pretty similar in weight/cone composition/and BL factor.
The price spread depends on the relationship with your supplier. These things are not flying off the shelves since 18's have ruled the market for so long and are still getting the job done.
The criterion for MY driver selection is:
over-excursion forgiveness (LabGruppen 20000Q's take few/no prisoners)
*sensitivity/power handling trade-off
*weight
*dealer support of the product
*price
The four top driver contenders for me are:
B&C 21SW152
RCF LF21N451
RCF LF21N551
18Sound 21NLW9600
they range in price from 600 to 900 bucks each.
So in theory, this box can be built using sweat equity for less than $1,000.00 each if you're resourceful.
availability
18 Sound isn't distributed too widely in the US. US Speaker and Loudspeakers Plus carry them but don't have many choices in their product range.
RCF and B&C have better availability and selection of drivers. They must market here more aggressively than 18 Sound does. That's a shame because 18 Sound makes beautiful drivers. My KV2 Audio wedges use all 18 Sound drivers in them and they sound VERY good and articulate.
Does the B&C simulate in this box well?
18 Sound isn't distributed too widely in the US. US Speaker and Loudspeakers Plus carry them but don't have many choices in their product range.
RCF and B&C have better availability and selection of drivers. They must market here more aggressively than 18 Sound does. That's a shame because 18 Sound makes beautiful drivers. My KV2 Audio wedges use all 18 Sound drivers in them and they sound VERY good and articulate.
Does the B&C simulate in this box well?
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