I’ve had a bunch of Curetronic 100M PCBs for ages and done nothing with them, so finally decided to start building them up as a test for Schaeffer UV-printed panels… only because I wanted to test out my version of the OpenMusicLabs clown/clone BA662, I built a single one up on stripboard.

For stripboarding I’ve switched to Veecad, which is much less pretty than DIY Layout Creator but at least allows for verifying the layout using a netlist exported from Kicad. Here’s the Veecad layout using a BA662 as the OTA:

In case you don’t have a BA662 clone or original to hand, here’s a stripboard adaptor for a BA6110. Without any other compensation it’ll be slightly quieter than the ‘662. I measured 2.68dB difference between the two, everything else being the same.

If you build the VCA, don’t be tempted to socket the transistors – I ended up frying a small pile of my clone ‘662s due to dodgy connections.

Here’s my redrawing of the VCA schematic.

As for the clone (…of the clone) BA662 – the OTA part of the chip seems to work OK. The 100M VCA doesn’t use the onboard buffer, so I need to check that as well.

Having given up trying to hand solder the SOT-363 bits on the OpenMusicLabs BA662 clone/clown, here’s a version with BCM847DS/BCM857DS transistors instead of the dust-like PMP4201/5201.

No idea if it’ll work. The specs look almost identical, apart from a tighter hfe tolerance on the smaller device which I don’t think will matter anyway.