I think I have one of the first pcb's as I ordered my Nava last year straight at its launch. I started summer last year up and until the snare drum and it was at that time that a lot of builders, including myself, discovered quite some mistakes or deviations between the original schematics, the BOM, the build instructions etc.
I then abandoned the project for a year until I picked it up again this summer and I'm happy to announce it is finished. and noise free!
Bass drum
I resisted the urge to cut the traces on the pcb and to make a bridge between the opamp and VR4 and Q6 and Q12 as per Vincent's proposed fix. I already had build that part and decided to wait and see.
To my surprise, I have no noise, no buzz, quiet as space and only BASS
Only mod here is I put tantalon capacitors as per original schematics.
I also put tantalons in all the Toms as per original.
Snare
Swapped the Q43, Q46, Q49 Collectors and Emitters.
Master
Did the mod with D195 and R471
Used shielded cable to the I/O board for the Master out.
Sequencer
Used the 24LC1025 eprom.
First test revealed a dead quiet (no buzz) perfect sounding Nava until..... I turned up the volume of the HiHat.. Noise, Buzz, overloaded distorted HiHat sound, decay pots not working, terrible.
As the decays didn't work I suspected the decay circuit and specially the 2sa798. Removed the 798, buzz and noise gone. Ordered 2 new 798's on Ebay....fakes...
Took the 798 out of the (known working) Handclap and placed it in the HiHat... Beautiful noise free HiHat sounds with working decays.
I have now ordered 30 SA992 to find and make a matching pair replacement of the 2SA798. Reason I choose these and not the 2N or BC series is that the pin out allows you not to have to cross C/B legs and you can glue them head to head for better thermal spread.
Will let you know how that worked out once I received them.
Currently running it with the AC adapter, but will change to my internal power supply mod.
Keep you posted,
Jeroen
