Hey Blondino,
I have built quite a few of these add ons and the preamp itself of course. It is a really nice version of the EQ section as you can use a wide variety of capacitor makes, including vintage mustard caps, if you have them.
If you get stuck for advice, try David at
[email protected], he is a jolly nice chap..
Trouble is, finding these in stock, you can get you can get 71BDF30-01-1-AJN from US Farnell, 71BDF30-01-2-AJN from US Digikey but nowhere seems to have 71BDF30-03-1-AJN (unless you backorder 25!) - finding a 71BDF30-03-1-AJN won't matter if you are only building the add-on EQ and you have the preamp already, and my usual go-to place, AML, is quoting back in stock by Nov this year. I don't know why this is, whether it is Covid-19 related or manufacturing problems..
I think Blore-Edwards are prototyping an equivalent switch designed by themselves (or at least this is the hint on their Facebook page), but this is only a guess and who knows when it will be available and how much it will cost... I tried messaging them, but didn't get a reply..
You want:
- 1 x 71BDF30-03-1-AJN - for the preamp gain switch (1 pole, 12 position, 3 gang) - you don't need this if you already have the preamp
- 1 x 71BDF30-01-1-AJN - for one of the eq freq selectors (1 pole, 12 position, 1 gang)
- 2 x 71BDF30-01-2-AJN - for two of the eq freq selectors (2 pole, 6 position, 1 gang)
Unfortunately you have to get the right switches (71BDF for through hole, not 71BD wired, AJN non-shorting, not AJS shorting, the AJS CAPI ones won't do).
Good luck hunting..
Thx, Mark