EWA / Elsdon Wonfor: Q-20-P preamp and Q-20 power amp test review

Neil McCauley writes: First, here’s how the makers describe their units: Q-20-P The Q-20-P complements the Q-20 power amplifier, it features MC, MM and one line input, a line-level output and a headphone output. The Q20P is designed to be as simple as possible in order to maintain signal integrity. It is ideal for the […]

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Colin Wonfor’s Clinic: PSU, material being the limiting factor perhaps?

Hello Colin. From reading your very cogent and helpful answers to those questions here I appreciate that you take the design of power supplies very seriously. I’m writing here out of ignorance of the design process and indeed materials used but I wonder if it’s coming to the point where the next set of advances […]

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Colin Wonfor’s Clinic: Top resistors

Dear Colin, Top resistors. Many threads with opinions on boutique coupling capacitors, but very little consolidated information on the sonics of resistors. Do you care to share your thoughts on the attributes of their favorite brands & types for specific tube and SS applications? How much of a difference does a good resistor make? My […]

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Colin Wonfor’s Clinic: Transformer noise through speakers when switched off!

Dear Colin, step up transformer noise. I purchased an amp from Europe that needs 240v [ I am on north American voltage].. I bought a step up/step down transformer to equalize the voltage. it works, but the transformer produces noise through the speakers, even when the amp is turned off. the transformer I bought was […]

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Colin Wonfor’s Clinic: Capacitor replacement in vintage Sansui gear

Q: I know vintage gear isn’t your business of course but, hey, I trust your expertise and so I wonder if you can help with a component issue please? I’m doing a Sansui restoration and the main caps are Nichicon & Elna. There are many differing capacitor ranges, do you have any specific recommendations? A: […]

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Colin Wonfor’s Clinic: What really are computer grade parts?

Dear Colin, Computer grade parts? What are computer grade parts.. such as Computer grade power-supply caps? Are these type of parts an upgrade and/or better than audiophile grade parts? For example, I’ve heard some people say, “I’ve upgraded my power supply caps in my amp to computer grade caps”. I don’t think I’d want computer […]

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Colin Wonfor’s Clinic: My meter isn’t going to zero any more on ohm ratings

Dear Colin. My meter isn’t going to zero any more on ohm ratings, and it apparently can’t be calibrated. It’s a fairly low-end Radio Shack autoranging model. I saw that the “what do you need for repairing equipment” on a US thread suggested a Fluke 114 or 115. Is that still the best, or do […]

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Colin Wonfor’s Clinic: Amplifier buzz even when power switch is off!

Dear Colin, I need some theories and hopefully answers please. This is a situation, neither I, not anyone who I asked, have encountered before. It is very simple and puzzling at the same time. Here it is: There is a faint buzz coming from the amplifiers, NOT the speakers, barely audible from a few feet […]

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Colin Wonfor’s Clinic: The Art of Electronics (Horowitz & Hill) 3rd ed; still the best?

Dear Colin, The Art of Electronics (Horowitz & Hill) 3rd ed… … as DIYers probably already know is now out, only 25 years after the 2nd ed. My copy arrived today. I’m not trained in electronics and make no claim to more than a passing knowledge, but have enjoyed these authors’ style of presentation since […]

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