Bootstrapped balancing acts

Some of you have probably already read this article.

http://www.jensen-transformers.com/an/ingenaes.pdf

If you don't want to build it you can get one of these.. http://www.thatcorp.com/1200desc.html Available from profusionplc.com for $4.93 USD. Designed by Bill using this bootstrap method.

Cheers,

elco

Ah, interesting.

Thanks elco, that might be worth checking out.
I could use some VCA´s to...
Anybody got any experience with this circuit?

i have built one of these for a uni assignment but i'm afraid i can't give u any usefull information other than that the low frequency rolled off a bit higher than i expected it too. i summised that it was due my difficulty in calculating the input impedences with the seemingly quite complicated RFI suppression (this was my first ever attempt to build something and i certainly wasn't the sharpest electronics mind back then to say the least!!!). i used a voltage follower as the bootstrap servo but i seem to remember reading that a bit less than unity is preferable.

i've always meant to revisit it now that i'm a tiny bit more knowledgeable(posibly using 3 DOAs with DC servos a la Massenburg plus the bootsptrap servo making a ludicrous total of four servo's per pre!!).

i'm still not the sharpest electronics mind tho so it's on a back burner until my little brain can get a firmer grip on it. i'd be very interested to know your results if you build one though.

Mark.