A few more pictures here:
Comments to the pictures:
First picture: Front baffel in the shown prototypes are removable for easy swapping drivers.
Last picture: In left side you see the top-to-bottom slot-vent, decided because I don't like the "OOmpphy" sound from long vents similar to the Synthesis-S1S-EX (2242H) that was tried copied. Because there are no very long vent similar to the S1S-EX, this system (with Electro Voice EVX-180B woofers) rolls off pretty high despite enclosure volume at 480 liters, but can easily be tuned very low by electronic boost. When boosting lots of air are moved via the slot-vent below the EVX-180B drivers Fs (28Hz), but creates no harm to the sound. Slot-vent in combination with electronic boost are choosen over traditional (passive) tuning by long vents, to avoid the OOmppy sound/port noise typical for long vents.
I choosed the EVX-180B over the 2242H because the EVX-180X offers a Fs at 28Hz and the 2242H are 35Fs.
I know there are better woofers out there than the EVX-180B, but developing this system has been a pretty expensive issue, and new drivers are about to be tested when economy are back on track.
(I should love trying 4 x the 2269H, but the "spare part" price I was asked to pay from the local JBL Pro distributor was far from attractive taken into consideration that my risk are ending up with no use of the drivers*). *MMS at 2269H are almost double the weight/mms of the EVX-180B, and that scares me a little since I am going for best possible acceleration factor. My fear are the 2269H need to be played loud before sounding sweet because of the very strong neo motor system. And my goal with this system are not "long-term P.A. capable sound pressure", but HiFi = the possibility of listening at low levels are of high importance.
My electronics (housed in the raw mdf box), has the following features:
Fully discrete design (No IC's, No OP-amps), Class-A operation.
Selectable crossover 45/60 Hz. (24/dB) and off-course a pass through option. (Two different frequencies in order to meet variation in music).
28Hz Q0.7 Eq./boost by selectable gain: +3,+6,+9dB to compensate for driver roll-off, and off-course a pass through option (0dB gain).
15Hz subsonic filter in order to protect drivers.
LF-variable output (0 to +6dB).
24dB/24dB crossover at 800Hz
Selectable 700-800Hz boost (+1,+2dB) to compensate for Al1501 notch in meeting the 4" Be. (but I guess Al1502 would do better..?)
Selectable 4500-5500Hz notch (-1, -2dB) to flatten out a little 5kHz peak I have in my system. (Perhaps a local problem generated by my room.?).
Selectable 20.000Hz boost (+3, +6dB) to compensate for the system roll off above 16Khz. (in order to add more transparency to the very Hf reproduction to the factory design of DD66000)
No Volumen at output for Al1501 and 4" Be. in order to keep cleanest possible signal path.
Kind regards
Henrik, DynaMax
www.dynamax.dk