The WHAWT/GUPPY Project by Joost Riphagen Wonderfully Harmonious Atypical Widerange Transducer/Grand ‘Uge Parallel Pipe Infrasonic Exciter A simple BR Widerange speaker that fits into an actual room and sounds pretty decent too. The project is actually half of what it should be, well make that half of what I was planning to build. After the endless raves about SE amps I really started to wonder what the fuss was about and decided to check some stuff out… Well that was more like it : sweet relaxed sounds with a great soundstage… gimmme gimme ! My speakers (Dick Olsher designed Black Dahlia’s two ways) up to that point did sound quite good and looked great (clad in high gloss British Racing Green) they did not offer anywhere near enough sensitivity (about 83dB @6ohm minimum…that’s what you get if you use Dynaudio drivers ;-) for use with micro powered amps. I had some interesting email exchanges with Thorsten (thanx for putting up with the nagging..) about a reasonably sized Hi Efficiency speaker… I’m still in University (and will be for bloody eternity to finish my Phd. ;-) and have one largish room to live and work in and although I love music and don’t mind looking at a speaker there are some practical limits to it’s size: that is about the size of Wilson Audio Watt/Puppies. I decided on a dual sub with small cabinets approach using a Fostex FE208 and a pair of powered Scan Speak 8552C woofers. Due to the form of the room (it used to have a really high (>3,5m) ceiling but this has been lowered to keep heating costs down I guess) I can accommodate dual TL pipe subwoofers of 2,4 meters hung in the corners. That way the corner loading will help the efficiency a bit and keep things relatively unobtrusive (well sort of)… At least that was the idea : use two powered subs (using my Marantz sm-500 poweramp) and forget about getting deep bass from a FR driver altogether. Using a bigger cabinet with the Fe 208 does not seem to yield much extra bass extension and the resulting response is pretty crappy too. The resulting cabinets needed for the Fostex FE 208 are only 18 liter and tuned to about 105Hz giving a –3dB point of about 100hz on it’s own, a highpass adds another -3db. My test cabinets are only slightly wider than the Fostex units and really deep. A hole in the back acts as the port and is stuffed with a bit of carded batt wool in the center of the box to mob up rogue waves A high pass filter is used to limit excursion of the FR driver (just a big cap ( 47uF MKP intertechnic parallel with a 220uF bipolar), it does not degrade sound much and does wonders for power-handling ) and as a starting point the notch filter using for the J horn was installed… The resulting sound is a bit less alive than straight in but also much better balanced. The midrange does have a upper midrange bump as expected with the FE208. Just adding the notch filter 1mH/2,2uF/15ohm did not cure it, adding a bit if capacity to the filter (0.5uF) did to a great extent: not perfect but very reasonable. The funny thing is that while it was never intended to be used without the subwoofers it is really very enjoyable and would make for a rather good speaker for small rooms where the bass would overload the room quite quickly. These things do not have any bass to speak off but somehow it does very accurately hint at the low end because it does appear to have as deep a response as the Dahlia’s (which do have response down to around 45hz and had so far slain all but some very expensive commercial speakers). Furthermore they have way better imaging and do wonders with voices. So far I have not started work on decent cabinets (they are still in chip wood now) and the subwoofers are also still on the drawing board, and will be for some time as the current project is a SET amp which is about to migrate from part collecting to construction phase. I have since added a supertweeter (the mod job done to a Motorola as described on the forum) and I must say that I could not live without it. All in all a small and enjoyable widerange speaker with pretty high WAF to boot.. Top