ESL57 vs ESL63

I have a variety of tube and SS amps to use with my 57's: Dynaco ST70, Heath W5's, Golden Tube SE40, Futterman H3 and H3aa's, Quad 303, 50's, 405, GAS Son and Grandson, BEL 1001 ...

I bought my first pair of 57's back in 1981 and kept them in use until 2000. After my move down south in 2015 I purchased two pairs - the prices were right! One pair from Rhode Island, one from England. Yes, the 57 ESL is a speaker that one develops a romantic attraction for!

The 57's and 63's still hold their place as the very nearly best speakers ever! Peter Walker's marvels! I have two pairs of 57's. This gives me the option of stacking them for improved image height. Regarding power requirements, both the 57 and 63 work best with 25 to 50 watt amps. This rules out flea- watt SET's. A Dynaco ST70 is an excellent choice for either. Since both have quite extreme impedance curves (30 ohms to 1 ohm) a partnering amp should have a low output impedance (<1 ohm) for best response. Both are voltage-limited because of arcing (20 volts/50 watts for the 57's, 30 volts/90 watts for the 63's). Because of these limits there is no need for high-power amps (risk of damage to the Mylar diaphragms).