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May 2013 Issue
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In your opinion what is the minimum amount of space that is needed at the rear of a Quad ESL-57 for it to perform correctly and also how much power is required to drive it to reasonable levels? I am assuming that when they where first produced they would have been run using amps like Quad II or something from the Leak range such as Leak Stereo 20 or 12.1 or 10.1. Will these still work or are they now considered too low powered?


William Ford 


The Quad ESL-57 is an open-backed dipole and needs space behind it

– but how much asks William Ford?




The Quad II-forty is a modern day variant of the Quad II. Using KT88 power

valves in push-pull it delivers 40 Watts and is perfect for Quad ESL-57s. 


From my own experience with ESL-57s and 63s, and from what I have heard of other systems, I would say around 6ft minimum. Looking at this more academically, a gap of 7ft to a rear wall will return the rear wave in-phase at 80Hz and the ESL-57 reaches down into the bass region little further, so my observations and experiences tally with what might be expected from theory, at least in simple outline (the modal behaviour of a room is complex). This is also enough distance to ‘lose’ higher frequencies, although rear absorption of some sort, like a colourful rug as a wall hanging, helps in this role and looks more suitable in the home than an acoustic panel (see, Acoustics section). 

Around 40 Watts is required from an amplifier for reasonable levels, without over driving the panels, and this is one reason why Quad produced the II-forty amplifier. There are of course plenty of 40 Watt valve amplifiers around nowadays because one pair of KT88s or EL34s power valves in push-pull produce 35-40 Watts. The Quad II and Leak amps will work but they are a little under-powered. Also, the Quad II has small output transformers and little bass push (Peter Walker told me this was deliberate, to protect the ESL-57s) so they would not be my choice. Go to for more on ESL-63s if you are thinking of buying a pair, and to our review of their renovation at, Loudspeakers, for more information. NK 



There is no address for John Lander (February edition, p 31) but if he or any other reader in the North Hampshire area needs service on cassette decks or other hi-fi equipment then I can suggest an excellent repair service. It is Ian Davies Electronics Services in Basingstoke. His workshop telephone number is 01256 421923 or mobile 07786636593. His website is I have found Mr Davies to be knowledgeable and efficient. As an example, I was given a Nakamichi cassette deck that was said to be “faulty”. Mr Davies soon found the cause of the problem and returned a fully serviced perfectly working machine at modest cost.


George Hulme 

Old Basing, 



If you need to get a cassette deck repaired use Davies Electronic

Services in Basingstoke, says George Hulme. 


Thanks George. You are a mine of information! I suspect that will be useful to many readers with tape collections and an ageing cassette deck on their hands. NK



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