Posted by JimGore [ 198.54.202.234 ] on December 04, 2005 at 08:58:02:
Hi all.
I am planning to build a set of 3 way speakers early next year.
Rweeter, I plan on using Morel MDT33.
Midrange, I plan on using Morel MW142
Woofer, I am in two minds:
a) (2x) Peerless 8" (HDS series) 850490
or
b) (1x) Scan-Speak 21W8555 8".
I have two questions:
1. Which bass? The cost of 2x peerless is a little less than 1x SS.
Whilst the 2x peerless drivers will have a higher SPL, the SS has a much better low frequency rollof.
Plotting the SPL in WinISD gives the following results:
Peerless drivers have an F3 of about 60Hz with box size of 30 lit.
The SS has a F3 of about 29Hz with box size of 57 lit.
The peerless pair have a better group delay than the single SS.
The volume of 57l isn't a problem, because these will be floorstanding.
I do however want to keep to 8" drivers so the cabinets are relatively narrow.
2. I am going to have midrange and possibly woofer / tweeter attenuation problems. The SPL of drivers are below:
MDT33: 92.5dB
MW142: 86dB
450490: 91.2dB (I will however use this in the 90dB frequency range)
(2x) = 90dB + 3dB = 93dB
21W8555: 87dB.
With regards to the midrange attenuation problem: Am I correct in saying that baffle step will help me out here if I use the (2x) peerless drivers? The baffle step should push the midrange SPL up by a couple of dBs.
Alternatively I need to find a good midrange with higher efficiency.
Any advice would be greatly appreciated.
Regards,
Jim.
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