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Letters and emails should contain complete name, address and daytime phone number. Letters to the Editor are submitted on the condition that Silicon Chip Publications Pty Ltd may edit and has the right to reproduce in electronic form and communicate these letters. This also applies to submissions to "Ask SILICON CHIP" and "Circuit Notebook".

Thanks for articles
on hearing loops

Thank you for the article on hearing loops in the September 2010 issue. I had no idea they were so different to what I had guessed at.

This town has a fairly good theatre, with good but not excellent natural sound. I have severe hearing problems, so was pleased when a loop was installed. However, if I wanted to hear (via hearing aids) the audio on the loop at the first performance I attended after the loop was activated, I found it necessary to point my face to the side of the stage, then turn my eyes without turning my head to see the action at the middle of the stage. Pointing my head towards where my eyes naturally looked gave a null.

I mentioned this to the staff and they denied the possibility but after a few weeks the system performed as I would expect it to. I cannot explain this fault which apparently was corrected.

This town is in the throes of a major road re-build, together with two bridges at the ends of the piece of road, about a kilometre long. Temporarily, street lights have been installed which are solar-powered. Some people wrote to the local newspaper, suggesting that all street lights should be solar powered, thus costing us nothing to run. A practical accountant or business manager should be able to understand the fallacy but I doubt if it could be explained.

Alan N. Brooks,
North Mackay, Qld.

Comment: lay people usually assume that solar power is cheap since it is powered by the Sun. If only that were true. Then it would make sense to get rid of all coal-fired power stations.

Toyota engine runaway – a
first-hand account

When I first read reports about the uncontrolled engine runaway problems in certain models of Toyota motor cars, I must admit to being somewhat sceptical. But having experienced the problem twice, as a passenger, I now believe it is true.

Early reports suggested that only the Toyota Prius vehicles sold in the USA were affected but further reading indicates that some other Toyota models also suffer from the problem.

My experience happened in Sweden, with my brother-in-law driving. The vehicle, purchased in Denmark, is a Toyota Urban Cruiser, manual diesel, no cruise control, about 5 months old, 11,000km “on the clock” and at a guess, with 250 hours total running time.

In the first incident, the driver pressed the brake pedal to slow down in traffic and the engine started pulling strongly. The driver then pressed the clutch pedal, engine revs went up to “redline” whereupon the driver pulled to the side the of road, stopped the car and then stopped the engine; no real drama. He then restarted the engine after about a minute and all was normal.

The second incident happened about 20 minutes later when he had to stop for traffic ahead. The driver pressed the clutch pedal, then the brake pedal to stop when the engine red-lined again. He stopped the engine and immediately started it again. Again the engine red-lined, was stopped again and restarted after about a minute, after which all was normal.

We phoned Toyota in Denmark, who arranged for the car to be checked by a major Toyota Agent in Gothenburg, Sweden. After a full analysis they found nothing wrong.

Interestingly, the car had never had an engine runaway problem prior to the incident and has been operating normally ever since.

The accelerator pedal was not caught by the floor mat or stuck open, nor did we carry an active mobile phone and I believe we can rule out “cosmic rays”.

I can well understand how accidents can happen due to a sudden and unexpected engine runaway, particularly to cars with automatic transmission, driven by elderly or inexperienced drivers.

Poul Kirk,
South Guildford, WA.

Comment: your experience is interesting although we note that exhaustive tests in the US have failed to locate any software problems. We have also not heard of any such issues with models sold in Australia.

QUAD review should have
avoided subjective tests

Thanks for the great write-up on the QUAD equipment in the August 2010 issue. As a long-time audio enthusiast I find these sorts of articles very interesting and more would be very welcome if the opportunity arises. I would be very pleased to end up with a set of QUAD equipment that was in as good condition as this collection appears to be. The descriptions and tests and comparisons were really good, however I would like to make some comments.

The primary question in the article is “How would the legendary QUAD system compare to the best audio equipment today? Did it deserve its reputation?” The question really has two parts:

Part A – “Did it deserve its reputation?” If we were to answer that we would have to go back in time and make some assessments of the QUAD versus its contemporaries and that would be hard. I think it’s fair to say that it did deserve its reputation as it offered reliable, high-performance audio equipment that had a unique physical presentation and many aspects of the circuit topology used concepts and techniques that are still valid today (“Current Dumping” is one of those).

Part B – “How does it compare to the best audio equipment today?” While this is an answerable question using a few simple comparisons, it’s only historically useful and not a reasonable basis to “bag” the equipment for your Serviceman. Let’s have a look why.

The technical tests should have probably compared the ETI or EA designs of the same era to the QUAD as a counterpoint to today’s equipment. I would be really disappointed if SILICON CHIP and its competent technical staff couldn’t design amplifiers as good as the tests show. Equally, it’s been possible for many years now to buy pre-built modules from various parts of the world which have stunning performance levels – I have purchased them myself.

Depending on the equipment that you look at, it is not hard to find consumer electronics equipment today that is technically a lesser performer than good equipment from years ago, as the emphasis has shifted from absolute performance to features like DSP (digital signal processing). All that aside, the pragmatic reality is that it’s not possible to detect good and less good at the incremental differences we talk about here. It’s all good.

There is no real validity in talking subjectively about major improvements in the sound obtained by driving the QUAD speakers with a different amplifier, etc. The only valid subjective test is a fully supervised double-blind test with statistical assessment to remove the observations of chance.

Nicholas is probably best advised to keep away from that as its like “Narnia and the Never-ending Story”. I suggest that sort of uninformed rubbish be left to the popular press that has little or no technical know-how but a burning desire to sell loads of “pulp fiction”.

Additionally, in a true double-blind test, it would not be possible to reliably detect the difference between the QUAD amplifier and the others as a discernible improvement, unless the auditors were smoking something illegal. Other journals and our small technical/audio group have demonstrated that a number of times over 30 years or so.

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