Horns and Triodes...?

I also like the Jeff Korneff amps. You might consider Jack Elliano's Ultrapath preamp too. That is getting a bit of attention lately.

For the speakers, the DIY route is very popular with the triode/horn crowd. For real front-loaded horns, try the Oris 150, kit or built. It uses a powered subwoofer under 150Hz, but can use low power SET above 150Hz. If you like a back-loaded horn, then the Hedlund Horns are a nice project, or you can get them already built by Hornet Audio. Not real cheap, but nice. Another nice back horn is the Lammhorn 1.8(not a kit). For the cheapest, but still very good sounding single driver Voigt Pipe setup, try the Cain and Cain Abby's or even making your own with Lowther or Fostex drivers. Easy woodworking, no crossover to build, and very nice sound when done right. You might be able to keep the whole package of source, preamp, amp, and speakers and cables under $5k, if you are a good shopper and do some DIY. And this would yield very excellent sound too.

I can't think of many actual horns under $1k. Maybe you might find something vintage for that, but it may not be in perfect condition. Perhaps some older Altecs. You could make some nice Voigt Pipes with Fostex drivers for under $1k. The Hornshoppe and the Z-horns with smaller Fostex are about it, otherwise. Ideally, you'd really want the 8" drivers with higher efficiency for a SET.

Regarding the amplifiers, getting a good SET with decent output transformers for under $1k will be a challenge too. Maybe a used FI X 2A3 would be possible. Or a Wright 2A3. The problem is that the really good output transformers can cost over $1k all by themselves.

Horn Shoppe and Decware are ok, but the Fostex 103 commonly used in the Hornshoppe "The Horns" are not capable of much volume level. A 4" driver can only do so much. Out of the Decware stuff, probably the Jack Elliano designed DRD amps would be my choice. Jack is a good designer.

Marco, I know a couple of people that have Cain and Cain Abbys and like them. I haven't heard them, but have built some Voigt Pipes with other Fostex drivers.(The Abbys are a Voigt Pipe cabinet). It's hard to beat them for the money, in a single driver speaker. I use Lowther EX3 drivers in the Voigt Pipes now, and I prefer the Lowther, but Lowthers are alot more money than Fostex. And also some people like the sound of the Fostex better. I think it is a worthwhile thing to investigate the Cain and Cain stuff. I built my own cabinets, and got Lowthers in them for the same cost as Abbys with Fostex. Voigt Pipes are an easy build.

I know a member who replaced his Silverline Sonata speakers/Electrocompaniet amp, with a pair of DIY Lowther Voigt Pipes and a Wright 2a3 SET amp, and they killed his previous higher power conventional system. He was shocked. I also know of a few other similar stories, including some Lowthers knocking out a pair of Merlin VSM. These are the newer Lowthers with the new improved design. A whole 'nuther smoke. I really think alot of members would be quite surprised to hear what this kind of setup can really do.

Yes, Marco you can look here for the plans(in metric, and INSIDE DIMENSIONS).
http://kosat.consultit.no/~ketil/lowther/voigtpip.html

Those are the original Lowther Club of Norway plans, and are the correct ones. Stick with those. The only beneficial mod to make, is to use my "swinging door" mods on the sides of the baffle-board, to extend the width for eliminating baffle-step losses that are common to narrow cabinet designs. Makes the bass much better. They do not ever swing forward of the baffle face, but can be angled backwards to reduce the bass augmentation for certain records. Contact me if you are going to make these.

IMO, these with either Fostex or Lowther, on your 300B will have those "twin dishwashers" permanently in the storage room.

Here's the rationale. Basically, when you remove the crossover from the speaker system, you are then achieving the same result as "active" speakers. You directly control the driver from the amp, with nothing in between. Big difference. Also, the traditional problems with crossovers and driver overlap are eliminated. Another big difference. Especially since the LaScala crosses over right in the middle of the vocal midrange. Third, you will get just as much top end extension(with Lowthers) and the (40Hz)bass will go lower than your LaScala's. Efficiency is very close, with the Lowthers doing about 100db/watt in the Voigt Pipe cabinets. And, there is a certain technical "synergy" between the SET amp and single driver speaker, that is just unmatchable with any other type of speaker on a SET. They are "made for each other", and you won't ever hear your SET better than on a pair of fullrange single-drivers. This is where the "magic" is.

One caveat: Lowthers and other single drivers take a VERY long time to break in. At the start, the bass is poor. They are stiff, and tight tolerances, so you have to start at low volumes, and then increase SPL over the first 30-50 hours. They don't come into their own till after 100-200 hours, and are not fully broken in until after 500 hours. This is very real, and not a "psychological effect".

Greg, that sounds very interesting. Do I take you to mean that there was no enclosure behind the Lowthers, but a tractrix horn in front? If so, that is quite unusual. What subs did you find that were fast enough to blend well with the Lowthers?

Greg, I understand the Tractrix front-loaded horn arrangement just fine, and there are some things like that already out there using Lowthers, like the Oris 150. However, most designs like that have a box loading of the rear of the Lowther, and I was most interested that your design did not load the cone in the normal manner.

I expected the rear radiations to play into this equation at some point, and was interested in your comments about that. I think the idea of an open baffle Lowther is interesting. It sounds to me like you ended up with some sort of "aperiodic" loading design.

To Paul: The horn contour is designed to have a "lower cutoff frequency" which is defined by the length and mouth size of the horn. At this "lower cutoff frequency" the bass sounds are no longer amplified by the horn, and the efficiency drops off correspondingly, like an acoustical filter.