Purpose of the diodes in the Bearhug FET compressor

[solderfumes]

I've been looking at building an AMZ Mosfet Booster as a nice simple break from struggling with flangers, which led me to take a look at Jon's Bearhug FET Compressor.  (Why make *just* a booster if you can build a compressor and get the booster for free?)

I took a closer look at the Bearhug schematic and I have a question about D4, in the rectifier section (working from the schematic at this thread http://www.madbeanpedals.com/forum/index.php?topic=6802.0.  Is it necessary?  It just goes straight to ground.  Without it, you'd have half-wave rectification similar to that in the Orange Squeezer, but with it... what's different?

[midwayfair]

it just seems to work better. It conducts the wave on the opposite swing -- it's not just half wave.

[jubal81]

Funny this came up today ...


I was just watching a Dave Jones video today where he goes over how to make an active peak detector and ponderificated on its use in a Bearhug kind of way.

[oldhousescott]

Yeah, provides a path to ground for the displacement current through the coupling cap C8 on the positive cycle, so that the charge on the right side of the coupling cap stays near zero. On the negative cycle, it doesn't have to overcome a stored charge on C8.

[solderfumes]

I see, that makes good sense.  Thanks!