Author Topic: Anyone ever build a Pineapple?  (Read 146 times)


Anyone ever build a Pineapple?
« on: February 24, 2021, 03:17:09 PM »
As I work through debugging my current projects I am scoping out my next one and thinking something along the lines of a Wampler Pinnacle would be nice. ;D

The Pineapple ( seems like a medium-difficulty Pinnacle-like project that would fit nicely into a 125B enclosure - but I have also read of folks having trouble biasing the multiple J201s in this design, and that for the original Pinnacle to work correctly you have to match all the JFETs.  However, there seems to be the addition of a couple of 50k trimpots in this design to (perhaps) address that issue.

So just wondering, has anyone here tried that one?  Any tips or warnings?



Re: Anyone ever build a Pineapple?
« Reply #1 on: February 24, 2021, 05:40:36 PM »
I've built a pinnacle clone - which is a modified BSIAB2 which has been built by many. As I understand it - JFET matching is not required in mu-amp designs - although selection for gain might be a factor. The two trimmers are on the output JFETs - the only one added by the pineapple that I can see is the one on the final make-up gain stage which is not critical. I had no issues with the JFETs in my clone, although I think I used 2N5457s instead of J201s.


Re: Anyone ever build a Pineapple?
« Reply #2 on: February 24, 2021, 06:05:34 PM »
Awesome, thanks GGBB! My Pineapple board is on its way!