Problem Solver

Q. I am thinking of buying a valve amplifier, but I don't know anything about electronics, and the reviews I have read so far lead me to understand that valve amplifier circuits must be regularly measured and adjusted to obtain optimum performance. Can you explain what I'd have to do?
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Q. I have recently become deaf in one ear. I now find that listening to stereo music on my hi-fi system is difficult. I have tried listening with stereo headphones but can of course only listen with the good ear to one channel, thereby missing out on the full sound. Is there a device that can reduce the stereo signals to mono signals in my headphones, so I can get all the music in my one good ear?
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Q. My 21-year-old stepson is blind. His sight has been slowly disappearing over the last ten years. He is a keen and talented musician with a penchant for Gypsy Jazz guitar. He can no longer use his iPod or read CD covers. He can use a program ‘Jaws’ to read aloud text on a PC. Is there any software available for a music server/similar device to find and/or read out tracks so he can play them on our stereo system?
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Q. Why it is necessary to ‘warm-up’ hi-fi equipment to obtain the best sound? I can’t understand what difference it could make to electrons whether they are travelling through a cold resistor (or capacitor or whatever) or through a warm one. Surely the resistance (and capacitance etc) is always exactly the same?
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Q. Why is it that some tweeters contain ferrofluid, while others don’t? What exactly is ferrofluid, where does it go and what does it do?
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Q. In your reviews of CD players you test for de-emphasis, yet whenever Steve Holding comments on these tests, he nearly always says that modern CDs are not recorded with emphasis, so the results of the test are immaterial. I have three questions in regard to this: First: What is emphasis? Second: Why don’t modern CDs use it, whereas it appears older ones do. And last, if no modern CDs use emphasis, why do you pay Newport Test Labs to run useless tests?
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Q. I don’t understand the difference between loudspeaker efficiency and sensitivity. Judging by the specification sheets I have downloaded, equal numbers of manufacturers use the word ‘efficiency’ as do those using ‘sensitivity’ but all seem to refer to the same specification such as ‘so many dB @ 1 watt (or 2.83v) @ 1 metre.’ Can you shed any light on the matter for me?
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Q. I have purchased a Pro-Ject Xpression 1 turntable. The standard counter weight is rated for cartridge weights 5–8g and weighs 65 grams. My new Audio-Technica AT150MLX cartridge weighs 8.2 grams, therefore I bought the heavier optional weight which weighs 75 grams and is rated for cartridges 8–12g. Both counterweights work but the 65g standard weight sits at the very end of the tone arm. My understanding is that the heavier 75g counterweight that sits closer to the tone arm centre will work better because of reduced inertia. But what about the extra 10g in mass?
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Q. Recently, I listened to several different preamplifiers through my system (JBL 4412A monitors, Rotel RB1080 amplifier) and was quite surprised by the differences in tone that I heard. I was led to believe that preamplifiers did not colour the sound. Are cheaper preamps like Rotel and NAD set up to compensate for weaknesses in low-cost speakers, so they have more treble to create the depth and detail that cheaper speakers often lack? Do you know of an affordable preamplifier (under $2,500) that is neutral in its sound?
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Q. I want to import my own hi-fi components direct from China. Is there any problem running hi-fi components rated at 220V on our 240V system?
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