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Discussion Starter · #1 ·
Alternate D3.8

If you did, tell me how you did it.



I have a ProAc 3.8 clone, knowing it is a 2.5 way, with a parallel; but no cross over; Scan 7" 8535 as a low pass only bass around 300 Hz. The toner and mid drivers (same 8535)cross over around 2500-2800 Hz, in 3rd order. So, it is the so call 2.5 way, it might be a nice way to do it for extra bass.

Interesting to know is both the mid and bass unit are 14-16 ohms type. In the X-over circuit, the toner is attached with pure resistor of 8-10 ohm to equalize the frequency response with mid. (and may be the extra bass.) I do not understand why to choose the 14 ohm DC resistance for the system. Mr. Taylor must have good reason for it. I believe this way, D3.8 drops to the 87db efficiency. ProAc developed a new version later, use parallel mid-bass to be 4 ohm two way system with much higher efficiency.The efficiency is raised to a much higher 91.5db. The speaker dimensions are kept the same. I think 87db is wasting my amp power and I do not appreciate the warmer tone also.

So, now I am planing to play around with the design by simply duplicate the D3.8 mid range crossover and replaced it on the current bass driver to make it parallel and change it back to 8 ohm system. Certainly, the output and the resistor for the toner has to be adjusted accordingly to match. I feel that the chance of success may not be great but large. If so, my next move will be add an active 2way crossover at 100-150 hz, and add sub-power plus 10" basses to evolute to be a larger 3 way 4 unit system.

Any suggestion, guide line?:rolleyes
 
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