There is a straight connection between last week’s system and that of jc morrison, as found in Tuned In! in issue 6 of sound practices. In it jc, apart from the system overview, spends quite a bit of column on line and pipe speaker systems and detailing the ‘new dinosaur,’ his bass crossover and amp, with schematics. He finishes with an argument for bi-amping.
teaser quote: ‘At 96 dB/1W sensitivity I can play The Melvins with a few triode watts. My friends are jealous. This system smokes on all of my current favorites: the Argo pressing of Britten’s “Noye’s Fludde,” the latest Praxis CD, Sacrafist, and a crusty Dinah Washington Mercury I found in the trash off Avenue B.’
my take
What I took away from the lines and pipes part of the story is the dissatisfaction with the boing of reflex boxes and the squashed dynamics of closed boxes. The opposite of that is open ‘enclosures’ that are not based on a resonance to produce bass. That is where jc went. He also enthusiastically lists the traits that make old fashioned good drivers. Open, non-resonant and good are not present in modern audio, high-end or not.
Connecting last week with this week—influence—it is instructive to compare last week,s triode P-P amplifier schematic with this week’s. There are to many similarities in circuit and PS approaches, component values and voltages to be a coincidence. But then there is enough difference in tube complement, front-end architecture and plain intended use (midrange vs. bass amp) that make me say that jc’s is not a copy of Arthur’s. If you work on something long enough, it will undoubtedly become yours.
The argument for bi-amping slots in with just about everything we read before for our ‘first stab at speakers’ topic. The transmission line system detailed here could have made an appearance there by itself. What jc adds are the power distribution (‘66%’) and frequency range (‘100 to 10,000 […] if only…’) observations. These are just two of the small gems that the article is peppered with. Absorb, combine and form your own connections, I say.
bonus tracks
Dinah Washington needs no further introduction, but here is some dope on The Melvins; Britten’s Noye’s Fludde; Praxis and Sacrafist. Weems’ 2/87 Speaker Builder article can be found here. Looking around for “Mullard” style, I found this nice—old skool—page. All the P-P amps there share the same architecture that jc is referring to.
practical note: in SP7, department of corrections: ’90V should have been pencilled in at the plate of the 71A rather than on the supply side of the plate resistor. Supply voltage is approx. 220V.’
Now go and read the article, see you next week.
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