Off with his legs

Right then, off with all the trim and legs.  3 screws for each side-strip and 4 for each foot.  72 screws in all….

Serial Numbers
Of the four ESL-57s here, two have consecutive serial numbers in the 19200s, which dates them to 1967.  This pair is a recent purchase, specifically for this project. They’re a bit dented about the grilles but, baby, those feet are like new.  The other two are 1975 vintage, with serial numbers 10 apart centred on 35500.  These have travelled the world with me, and been in regular use since I bought them in 2003 from someone in Luton who didn’t think it was safe to keep them with small children.  Their grilles were pretty much perfect for a while, but have now suffered slightly from being used to provide music for games of musical chairs – children 1, speakers 0 so far.

For reference, here is a list of serial numbers by date of manufacture – helpfully posted by someone on the Pink Fish Media forum.  I can’t vouch for its accuracy but it looks plausible:

1959 2000 – 4000
1960 4000 – 6000
1961 6000 – 8000
1962 8000 – 10000
1963 10000 – 12000
1964 12000 – 14000
1965 14000 – 16000
1966 16000 – 18000
1967 18000 – 20000
1968 20000 – 22000
1969 22000 – 24000
1970 24000 – 26000
1971 26000 – 28000
1972 28000 – 30000
1973 30000 – 32000
1974 32000 – 35000
1975 35000 – 38500
1976 38500 – 41000
1977 41000 – 44000
1978 44000 – 47400
1979 47400 – 50300
1980 50300 – 52100
1981 52100 – 52800
1982 52800 – 53000
1983 53000 – 53150
1984 53150 –

I was surprised when I got the older pair to find how different they were in colour from the 70s ones.  Their grilles are a darker and more golden shade of bronze, where the later pair are a paler colour, almost pink in comparison.  Obviously the vagaries of cameras and monitors makes this fairly pointless, but I’ve tried to photograph the difference:

The left hand side is a good reproduction of the later grille colour (on this monitor).  The older one is more yellow-gold than it has come out, though.

There are other external differences.  The wooden trim is darker in the later speakers, and both the side trim and feet have a different, slightly sharper profile.  The trim is also attached with different screws – shorter and apparently anodised a reddish colour to match the wood.  The earlier feet have a wooden dowel running up into the bottom of the speaker – this is missing on the later ones, which instead have some sort of metal bolt attaching the feet to their bases:

Despite these differences, both pairs sound identical, and in fact we’ve spent a couple of evenings listening to mixed pairs without any perceptible imbalance.  I’m not aware of any change of internal structure during the life of the ESL-57, apart from the EHT board being originally in epoxy and later in beeswax.  Nothing to affect sound.

Also, importantly for construction purposes, they are identical in overall size and shape:

In any case I’ll obviously be putting one of each pair per side, symmetrically arranged.

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