The Drivers
This is probably the simplest part of the process since I've already have a bias - ScanSpeak drivers all round. However, there are still some choices to be made as SS produced a moderately large selection of drivers at different price range and performance.
Tweeter
It was a 3-way contest between the old D2905/990000 Revelator against the newer R2904/700000 and D2904/710000. Though the 990000 has aged gracefully, its performance is still one of the best $ can buy. However, I was itching to try something new, thus, it was down to the R2904 or D2904. From performance standpoint, on paper they are equilvalent but differs quite considerably $ wise.
After much contemplating, the R2904 won despite the high price. For aesthetic impact, I'll be using the silver faced model rather than the visually "tame" black face plate. This is a pricey driver to say the least, my hope is that it will live up to its illustrious reputation and price. As assurance, this unit is used on many high performance and prestigeous brands such as Sonus Faber Cremona/Homage range, Krell LAT-C1000, GamuT L3/5/7 and many others. So if my design turns out crappy, it's not the drivers' fault.
Mid-Range
For the Mid-range driver selection, due consideration need to be given to the fact that the R2904/700000 tweeter specified output is 94dB for std 1w power measured @1m. Other important criterias for the mid selection are high sensitivity and wide FR coverage. The 12M/4631G00 @89dB output matches well. At 4Ω nominal impedence, I'll be using 2 units in series since connecting these in parallel would bring the impedence down too low @2Ω.
The FR looks good with coverage from 200Hz till 5kHz. Off axis performance started to drop @2kHz region. At 5kHz, 30 degree off axis is only 4db down. Therefore, base on the manufacturer charts alone, xo point can be set at 300Hz and 3kHz respectively. Of course, the actual xo point be determined from actual FR/Phase measurement using Speaker Workshop with the drivers mounted on the final enclosure. The design in using TWO drivers lined horizontally somewhat compensate for the off axis performance (or so I hope).
Woofer
Lastly, for the lower registers I selected the 18W/8545-00. Originally intention was to use the top of the range 18W/8531G00 Revelator but decided against it. On paper, the low frequency performance between these two are equilvalent. The Revelator asking premium is largely due to its excellent mid-range performance, which in this case not be called into service.
Then again, I might change my mind at the last minute since I've not drill the mounting holes. Not only that the current pair of front speakers IS using the Revelators as mid-bass units, future design upgrades will likely follow the same path... ah, compromises, compromises....#1
--------- update: 08 Aug 2006 -----------
As expected, I ended with an ALL REVELATOR system. Considering the vass amount of effort dedicated to this project, it does not make much sense to stinge a couple of hundreds. Thus the final ensemble [see left]... No regrets here as it is intended to be a 'no-compromise' design to start off with.
Initial functional test of the mid unit was surprisingly good even without any enclosure. The superb image focus was fault-less. As expected from such small drivers, bass slam and depth is non-existence. The tweeter too sounded impressive. Even out cold from the packaging, it sounded mellow without any harshness.
These results are truly promising. Feast your eyes on the actual beauties. 
FedEx package from MadiSound containing the D2904/700000
The premium ScanSpeak Ring-radiator tweeter. For aesthetic impact, the silver face plate model was purposely chosen. The local distributor was not able to supply just ONE unit - thus it was necessary to import/purchase via the internet#2. Thankfully Madisound sells per unit rather than per pair. Excluding the freight charges, it is very close to the local retail price.
#1 As expected, I did not stinge and went for the more expensive revelator woofers.
#2 Madisound initially refused to ship due to the existence of a local distributor for Sg. Thankfully, they did not have stock and granted permission for Madisound to supply me the unit.
Last update :: Sunday, December 17, 2006 10:17 AM