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This page is posted
as something of a precursor to the construction of our site. |
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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 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. |
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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. |
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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. |
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| Quad ESL57 Rebuild:
A compendium of Sheldon Stokes excellent work downloaded from here. If you are a Mazda Miata nut or a "go fast" junkie of any stripe, Sheldon's site has some great pix and info . . . . highly recommended |
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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 |
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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 . . . |
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| 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. |
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| W. Marshall Leach Jr. on the subject of noise: Downloaded from here and then collated into one large, navigable PDF. |
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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 push-pull output transformers that materially improves the AC and DC balance of the composite pair so formed. AC balance is very important to low-value, high frequency distortion and feedback loop stability and is typically very poor in conventionally wound push-pull output transformers. The measurements shown for a Dynaco ST 70 output transformer illuminate the problem very well . . . |
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| Push-pull Theory:
Excerpted from "Applied Electronics" published by the MIT Press |
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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. |
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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: 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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| Loudspeaker Enclosure Design - Damping with Acoustic Resistance
- Parts 1 & 2:
This is a seminal piece of work that as far as I know has been completely ignored. Written in 1956 by E. J. Jordan , then in the employ of Goodmans Industries Ltd. UK, this paper outlines the manifold advantages of bass loading using what he called an "Acoustic Resistance Unit," an ARU, to control low frequency damping. Completely unaware of Jordan's work, I independently developed his method about 1980 and have used it with great success ever since. I called it "Distributed Acoustic Impedances" or DAMPS and in the estimation of many, many listeners across some 3 decades it is simply the best loading method yet developed, far surpassing the ubiquitous Thiele-Small alignments . . . |
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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. |
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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 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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Visitors since |