Kana813, I referred to Black Plate 5692, not black base, although there are black base RCA 5692 tubes. The Red Base 5692 is the famous "sought after" one, but there are non red ones also. Also the "Black Plates" are actually really deep charcoal grey.
My speakers are Voigt Pipes that use Lowther EX3 drivers. You can find info on the drivers here:
http://www.lowther-america.com/
And you can find Voigt Pipe plans here:
http://melhuish.org/audio/diy12.htm
The Voigt Pipe plans shown here are the same as what I used from the Lowther Club of Norway, but this guy used a Radio Shack speaker in his. It doesn't matter, the dimensions are exactly the same.
The Lowther Club of Norway has removed the plans from their site.
If you are going to make these you should contact me when you get ready to do it. I've been down the road.
The sound is awesome for low-power SET amps. Of course, the bass is quite sharply rolled off below 40Hz, but I don't miss that too much. Even the really good multi-way designs don't really go too much lower than that, in reality. Most are -3db at 32 or 28Hz. Unless you listen to alot of organ music, you'll never know it. The lowest note of a bass guitar is 41Hz, so if you mostly listen to popular music, its fine. That's only half an octave less bass in the least used area for music. The rest of the spectrum is spectacular, and the imaging is the best. Small sweet spot, due to directionality. Incredible dynamics and detail. Totally coherent. High end goes to 20kHz. Get the new series of drivers, as the previous upper midrange anomalies have been worked out. Don't buy a used pair over 6 months old. New is best. The EX3 will cost $895/pr and will give 100db with 1 watt input, when loaded into the Voigt Pipe cabinets. A 45 or 2A3 amp is plenty. A 300B is more than you need, but still sounds great. I ran them on 1 watt for 6 months with my MicroZOTL, but I felt I needed a little bit more headroom. My new Berning custom 45 amp will be here in a couple of weeks.
You can build the cabinets out of MDF for under $100. If you want fancy wood, you can do that too, but it costs more. I recommend that you at least make the front panels out of a good hardwood. It looks better, and it takes away a little harshness that the MDF has. I used oak fronts and MDF backs, and they look great and sound great. I also made a modification to mine that reduces the baffle-step effect under 380Hz. Due to the narrow cabinet design, the baffle reinforcement of the frequencies under 380Hz drops off due to wavelength. By adding some "swinging doors" to each side of the Pipe, you can bolster the mid-bass frequencies, and make the frequency response alot smoother in this area. Also, since they swing, you can tailor the backward angle on both sides to give adjustability to your midbass response, and tailor it to the music and to the room needs. If you need more info on this mod, email me for details. I have been living with these for about 6 months now, and I have no desire to look at any other speakers. These give me everything I need.
