Cabinet design for ATC 3 way active

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Lukec

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Hi,

Looking for some advice; i have recently purchased a pair of used ATC PA65 speakers and intend on re housing the drivers into a domestic friendly cabinet. The componets are the same as used in the SCM150 - SB75-375 (short coil i think) SL magnet, 3" super dome mid, 1" HF - 3 way active amp / crossover module. As the crossovers are ATC and as per SCM150, the HF and Mid are sealed i am assuming only thing i have to get right tuning the cab to the LF driver. I am aware of keeping the driver alignment the same and getting the hf,mid and LF as close together as possible.

I would appreciate any advice on how best to load the bass - reflex as per scm150, sealed in suitably large enclosure or try a transmission line? Also thinking of using quality birch ply 25mm for caninet - is this a better choice than MDF acoustically? Lastly if i go reflex and use Winisd or Bass Box Pro - how accurate are these models? Can i assume it will work as modelled or will it need some tuning?

Thanks in advance for any input -want to get it right!
 
Lukec said:
Hi,

Looking for some advice; i have recently purchased a pair of used ATC PA65 speakers and intend on re housing the drivers into a domestic friendly cabinet. The componets are the same as used in the SCM150 - SB75-375 (short coil i think) SL magnet, 3" super dome mid, 1" HF - 3 way active amp / crossover module. As the crossovers are ATC and as per SCM150, the HF and Mid are sealed i am assuming only thing i have to get right tuning the cab to the LF driver. I am aware of keeping the driver alignment the same and getting the hf,mid and LF as close together as possible.

I would appreciate any advice on how best to load the bass - reflex as per scm150, sealed in suitably large enclosure or try a transmission line? Also thinking of using quality birch ply 25mm for caninet - is this a better choice than MDF acoustically? Lastly if i go reflex and use Winisd or Bass Box Pro - how accurate are these models? Can i assume it will work as modelled or will it need some tuning?

Thanks in advance for any input -want to get it right!
Click to expand...

Everything has an effect. You should keep the baffle the same width, the driver to driver spacing the same and also the 'depth' of the drivers on the baffle (i.e. don't inset one driver more than it is on the current design).

The bass alignment could be played with without too much trouble, but it should be suitable for the drivers T/S parameters.

IMO, you would be best just re-finishing the current cabs. How about a nice birds-eye maple or zabrano veneer with wax polish or oil? Some new grill cloth and they could look very tidy.
 
Agree refinsihing the existing cabs would be the easiest option but i feel a new enclosuire will benefit the drivers as the PA65 was designed for live use & clubs etc. Its a relatively small volume sealed enclosure made from 3/4 mdf - its designed to work with a sub, no electronic high pass filter on the LF but the cabinet does that. I'm hoping a better constructed / braced cab and tuning the LF driver for use without a sub will bring some big improvements. Current design has all driver in the same plane in the front baffle so i wont mess with the physical time alignment and repeat this - has anyone had experience with this bass driver and reflex enclosures?
 
Sounds like you just want to bring the enclosure down to the floor then, and add a low tuned bass reflex. Ask ATC for the drivers T/S specs so you can model the cabinet porting.
 
I know its a different speaker but I've got scm50asl's,
I once had a look inside and behind the bass driver the cabinet is full of wadding right to the back of the driver, also the port bends right round to the back of the driver.
maybe useless info. but you never know.
 
thanks for the info, will have to try and find out more details on the way the SCM 150 is tuned - intereseting re the SCM50 port, must have been quite long.
 
You could ask them for a price for unfinished SCM150 cabinets and baffles.

It might also be worth asking Wilmslow Audio whether they have cabinet plans for the kit ATCs they used to sell.

But first get them to confirm that the bass drivers are suitable.

Paul
 
Also reccomend just copying an ATC SCM150 if you have all the drivers.

I'm sure ATC will tell you the volume of the cabinet, the baffle size and the length of the ports.
 
Agree its the only sensible option, to get as close to the design that ATC spent alot of time developing for the best results. Thanks for the advice
 
The cabinet volume of the SCM range of loudspeakers is easily identified using the number ie. SCM50 is 50ltr, SCM150 is 150ltr etc.

Modelling a ported box from here is simple enough. Enter the TS into a program such as WinISD, make the volume 150ltr and then proceed to explore the options.
 

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