QUADs have drivers made of stretched Mylar (a special plastic sheet) that are moved back and forth by high-voltage electrical force fields
The world's best-sounding stereo system?
Have you ever seen the frequency response graph?
"When I finally sat down to listen I couldn’t believe what I was hearing. It was the best sound I’ve ever heard in my home — and I’ve had some unbelievable sound systems in my living rooms over the years." ~ www.nbcnews.comKen Kessler article mentioned in above (PDF)
Quote from: 2Bdecided on 08 February, 2013, 12:15:49 PMHave you ever seen the frequency response graph?QUAD ESL-57 frequency response graph (unrebuilt tweeters)
Quote from: 2tec on 08 February, 2013, 03:31:40 PMQuote from: 2Bdecided on 08 February, 2013, 12:15:49 PMHave you ever seen the frequency response graph?QUAD ESL-57 frequency response graph (unrebuilt tweeters)Yes, that seems to be just the tweeters though. The full response is in Google image search.
FWIW, Philips Classics used the QUAD ESL-63 as its reference speaker for many years. I don't know exactly when they started using them, but it must have been from the early 80's until the mid 90's. I bought my pair in 1983.It's very well possible that their recordings from that period sound superior on the ESL-63 because they were recorded, mixed and mastered on them.
The ESL-57 was quickly adopted by the BBC for monitoring the sound quality of their broadcasts. The BBC eventually replaced them with moving coil based monitor speakers developed by several manufacturers to meet BBC specifications, such as the highly successful LS3/5a, that were more easily transported and stored, and were more representative of typical contemporary hi-fi speakers.The ESL- 57 was renowned for sonic transparency and very low distortion. A properly configured stereo pair would generate a very small 'sweet spot' where the sound stage snapped into focus. This led to criticisms of the speaker's directionality but in practice was rarely a problem and had the benefit of reducing the effects of room resonances. Its superior sonic characteristics were offset by its moderate power handling, the need for a large room, and moderate bass extension.
PrinciplesQuad have always had a very straightforward engineering view of their products, and insisted that all amplifiers of adequate quality sounded the same when used within their capabilities, and that speaker cable had no sound at all, unless ludicrously long and thin wire is used.To verify or disprove that amplifiers of adequate quality sound the same, Quad commissioned James Moir to organise and conduct listening tests comparing Quad II, Quad 303 and Quad 405 amplifiers. Statistical analysis of the expert listening panel's scores showed that "the decisions of the panel were no better than might be expected from sheer chance".
For the dipole drivers in the ESL63 to reproduce frequencies below 100hz at even moderate levels the panel needs to move back and forth enough to create IM. A good subwoofer crossed at 80 to 100hz removes the need for the movement in the ESL63 with a corresponding drop in IM.