More old silicon – the EL2k headamp…

After my adventures with the obsolete BUF03 buffer comes a design with another discontinued buffer-chip – the Elantec EL2008 😀

The EL2008 is definitely an overkill-device for audio duty. It’s got high bandwidth, high slew-rate and a 1A current capability with a built-in limiter. Like the BUF03 it was originally intended for video applications and like the BUF03, it has also been discontinued for a decade or so. There is also an EL2009 with even more impressive specs for bandwidth and slew-rate if you want and since both ICs should work in this design coming up with the name was pretty simple – the EL2k.

The design itself is a fairly straightforward “buffered op-amp” circuit, the only “tricks” being a resistor between the opamp and the buffer (because the buffer needs a controlled source impedance) and a current-regulation diode (CRD) to bias the opamp into class A (something else that was very popular in diy headphone amplifiers 10 years ago – my age is starting to show here I guess…).

I’ve possibly gone a bit overboard with the heatsinking, but this was the type of layout I had in mind and it seems to work well (electrically at least, there are some mechanical niggles). The input caps are ClarityCaps ESA which probably also qualifies as overkill, but I am sure they do no harm 😀

The opamps used are LME49710s because I had a pair to hand when I did the test. However, in my opinion the obvious choice for this build would be another one of “yesterday’s heroes” – the OPA627. Back in the day when the EL2k buffers were around, the OPA627 was pretty much the king of the audio-grade opamps so I think that match is sort of meant to be. The OPA627 also has a warmer, less clinical sound signature that might offset a bit of brightness here.

I have only listened briefly to this design so far, but the immediate impression is “detail, loads of detail” Whether this turns into listening fatigue in longer sessions I don’t know yet but we’ll see when I get some more time. In any case: the guy that sold me the Elantec buffers told me “to build something awesome with them” – not sure I succeeded, but I definitely tried 😀

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