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| This page is something of a precursor
to the construction of our main site. Here we have available a number of PDF files that will eventually be available from our site's main navigation page(s). In the meantime, and so that those viewing posts archived on various list servers, the JoeList digest for instance, will find live links in long archived posts we will keep this page as permanent resource. |
| Click on any of the three links to the right to initiate download |
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| PEARL CryoValve Tubes: One fairly comprehensive page of process description followed by several pages of customer comments -- alright, raves -- on the sound of these tubes. The latest version, 1.07, includes a HiFi News and Record Review interview with Ed Meitner of EMM Labs wherein mention is made of the benefits that accrue to cryo-treated vacuum tubes. |
87 |
MUCH |
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| PEARL RB300 3CX Data Sheet: The RB300 3CX is a 300W anode dissipation rated, metal-ceramic, audio triode intended for low-velocity (i.e. quiet) fan cooling. Although not presently available due to difficulties with single-source supply the data sheet is nonetheless an interesting download. |
234 |
Ditto |
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| Quad ESL 57 Service Data: Based on the original Quad service data manual. Complete with reset text, new, color photos and line art. |
2.25 |
Ditto |
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| Quad ESL57 Rebuild: A compendium of Sheldon Stokes excellent work downloaded from here. If, BTW, you are a Mazda Miata nut or a "go fast" junkie of any stripe, Sheldon's site has some great pix and great info . . . . highly recommended |
435 |
.Etc. |
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| Altec Lansing 260A Product Literature: This is a rebuilt version of the original literature for a 260W, 183# power amp that while commonly mistaken for a boat anchor is, in point of fact, an altogether astonishing performer once modified |
140 |
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| Altec Lansing "Voice of the Theater" Product Literature: High quality , full color scans of a '60s vintage, 5 page, original Altec brochure. A nice little nostalgia trip . . . | |||
| JFET Input, UL Cascode, Passive RIAA Stage: While I don't suggest this is a "world beater," it has handily trashed any number of commercial offerings. It's presented here as a "freebie" and that's as far as the offering goes. If tech support is desired, you'll have "pay the piper" ( i.e. me) for the time it'll take to sort through your inquiries. Do note that the embedded links in the doc do not as yet have the supporting PDF docs behind them. |
18 |
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| W. Marshall Leach Jr. on the subject of noise: downloaded from here and then collated into one large, navigable PDF. |
4.3 |
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| Twinning Push-pull Audio Output Transformers: This is a very brief, schematic description of a method for connecting pairs of single coil output transformers that materially improves the AC and DC balance of the composite pair so formed. |
40 |
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| Push-pull Theory: excerpted from "Applied Electronics" published by the MIT Press |
1.8 |
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| Fostex NF-1, Near-field Monitor: This is a very interesting speaker. Fostex have done some excellent research and FEA work to arrive at a cone shape not seen before, one that opens a whole new line of inquiry for this developer. |
6.6 |
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| Cone and Diaphragm Materials: Published by Pioneer Corp. about 1982, this paper is an
excellent and thoroughgoing technical review of then-recent developments of materials
for loudspeaker diaphragms in Japan. Detailed are developments of beryllium and boronized
titanium diaphragms for high frequency applications and carbon-fiber reinforced olefin
and polymer-graphite materials for use, in the former case in mid- to low frequency
applications and in the latter, applications across the audio band. Much information useful in the assessment of materials for diaphragm applicability is given. |
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| Critical Damping: Missing Link in
Speaker Operation Parts 1 & 2: Part
1 - The Amplifier Damping Factor and its Application to Speaker Performance: In audio
reproduction, a subject of considerable importance to the high-fidelity enthusiast
is amplifier damping factor and its effects on speaker operation. Misconceptions
have arisen concerning this subject, and vague and incomplete answers have too often
been given to the many questions involved. Are the high damping factors found in present high-fidelity amplifiers byproducts of high-feedback circuits and, as such, unimportant in the operation of the system? Or is the ultimate, as some loudly proclaim, to have the highest possible damping factor built into the amplifier? Why does a particular speaker sound better with amplifier A than with amplifier B, although both show identical frequency response and power capabilities under bench checks? Why does that $2.00 speaker with the 6-ounce magnet (inefficiency and distortion included) seem in some cases to have more bass than the high-fidelity unit with the 5-pound magnet? Why is it that one enthusiast found reproduction more pleasing when he used a little current feedback from the output circuit yet another didn't when using the same circuitry? [ . . . ] |
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| Power Distortion: Written by Kurt Steffenson of JoeList and TriodeFest fame and edited by yours truly this is a post to the JoeList made about 2000. Kurt engages the matter of "current driving" bass units in a most intriguing article. |
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| The TungSol 5881—A New Beam Power
Tube: [ . . . ] For a long time there has
been a growing demand for a tube with dynamic characteristics like the 6L6 but of
a design that would cope more vigorously with the problems encountered in a heavy-duty
audio output tube. After considerable experimentation, the TungSol design and development
engineers have evolved a design which embodies many features which should qualify
it as a successful candidate. This is experimental type (the RETMA commercial number
is 5881), it has some intriguing features. Update 3_03_04: Thanks to Dave Crittle of Retrovox Valve Audio in Australia I've been able to add the original TungSol data sheet to this article. |
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| The High-End Mythology of the Toroidal Power Transformer: If you look at the AC power transformers used in most high-end audio equipment these days, you will find that a very large majority are toroid transformers. These donut-shaped transformers seem to have taken the high-end industry by storm. Their major advantage is that they do not radiate much of a magnetic field--a very useful property. Dealing with stray magnetic fields from EI-frame transformers (non-toroid) inside a high-end component is not a trivial undertaking. While toroidal transformers have one significant advantage regarding radiated magnetic fields, toroids have a number of "problems" that severely limit their performance in high-quality audio equipment. We’ll try to help you understand what these problems are and show you how another kind of transformer, the EI-frame transformer (that’s a capital I, "eye," not a lowercase l, "el") can be a superior performer if designed, manufactured and installed properly. [ . . . ] |
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| Inherent Feedback in Triodes: The triode is imagined to be replaced by an infinite- impedance pentode with a fictitious EMF in the grid circuit to represent the “back action” of the anode on the field at the cathode It is shown how this transformation makes it possible to obtain practical triode circuit formulæ from conventional feedback theory. [ . . . ] |
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| Tonearm Geometry and Setup: Optimum geometry of tonearms has been the subject of several articles over the last three decades, the earliest complete mathematical study being that of H. G. Baerwald in 1941. His analytical study of tracking-error distortion showed that optimum geometry of a tonearm of given effective length will have a corresponding offset angle and overhang. [ . . . ] |
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