“First, I’d like to say I totally understand what Clark is getting at. A very simple “full range” speaker powered by a very simple system can be very magical and give you a clear window into the music. None that I have heard, even the high end examples using Fostex and Lowther drivers are terribly accurate from an objective frequency response standpoint, but in some ways that isn’t all that important as humans are very good at “auto correcting” frequency response anomalies.
That said, if you want shimmering highs and bass impact in your gut, a multi-way system is required.
…Widget”
Well, sort of. But that does not describe what I listen to. Aside from one single Fostex speaker design, which employs tricks like a cabinet glued with an adhesive used otherwise only by NASA and a custom one-off transducer, I have never been pleased either by the little (four to eight inch) Lowther, Fostex or other systems. My system consists of a John Wyckoff designed Hammer Dynamics Super 12 (no relation to the St Louis made Super 12 transducer) pair and a Nelson Pass designed First Watt F1J transconductance amp built by hand by Papa himself.
Shimmering highs are no problem. Those little Lowther and Fostex speakers are always run full range and are asked to handle all the treble. They are too large to give the results we both like. They are also too small to give the bass we like and their frequency response is indeed noticeably lumpy. The Super 12 speaker is a twelve inch ported design with a precise French tweeter of deliberately minimal footprint (a custom piece) suspended over the edge of the whizzer cone. As designed, the little tweeter handles 9700 to 20000Hz with a simple crossover.
While that results in very good sonics there was still room for improvement. Nelson Pass’s first First Watt design was the very tranceconductant F1; the second was the somewhat less purely transconductant F2. He later came up with a power JFET modification for each; he offered to refit the F1s himself and built a handful (three to five, not sure) F2Js and help out with modifying the one hundred existing F2s. All but three of the one hundred F1s built were eventually modified to F1Js. I have one of those and one of the “built as” F2Js. What these do is solve several of the single driver issues.
A transconductance amplifier supplies a current, rather than a voltage, that closely follows the input signal. If the driven speaker has a tight gap and a suitable magnet structure, the control over the cone is much more precise and more, shall I say, firm, than a voltage driven arrangement. While most transducers are designed to deal with the sloppy nature of voltage drive as best they can, most single driver speakers are not. They respond very, very well to current drive. The result is twofold. Frequency reproduction inaccuracies are greatly lessened and bass response, besides having excellent linearity, is extended downward. In the case of the Super 12 it still does not qualify as “bass impact in your gut”, but it is so improved it is startling. I did eventually install a subwoofer but I never use it anymore, it is simply not needed.
I did mention that the system was designed with a crossover and I did build them. After a period of adjustment (of my listening and expectations, not of the system), I acquired an F1J and replace my F2J with it. The results were so outstanding I decided to try it without the crossovers and the Zobel and instead inserted single 2mfd caps in the lines to the tweeters. FYI, in tranconductance circuits the crossovers or caps are wired in series and as close to the amp, not the speaker, as possible.
The result was again very pleasing and I have stayed with it. The system efficiency gained 6dB, to 101-103 and with the ten watt F1J a quarter watt will drive me from the room.
So… My system is technically a single driver augmented, has mucho bass, very good frequency response accuracy and still “very magical and give you a clear window into the music”. Everyone who has heard it is absolutely fucking amazed.
