Hey EdBass!
I agree that it would be good to add some modern innovations to the classic Sunn design. But I wouldn't be too worried about copying Conrad's "original" design. The "Smiley Face" amps were literally Dynaco Mark III power amps with the pre-amp adapted from Dynaco designs, so it wasn't all that original. But it was a smart idea to adapt a hi-fi amp (read clean and undistorted) for bass amplification. The 200S was improved but not radically different; compare the schematics. In retrospect, I'm surprised Sunn didn't run into legal problems with Dynaco (perhaps they did?).
No criticism here, after all Leo Fender adapted existing Western Electric designs for his amps as well. And Jim Marshall based his first amp on Fender's 5F6A Bassman (with some tweaks). I think Conrad was doing the same thing. And we may have different ideas about what "original" means. I guess the point is that truly original engineering has been rather limited in the last few decades of vacuum tube amp design. Improvements, variations, adaptations for sure, but it's been based upon a backbone of vacuum tube amp designs that stretch back around 80 years.
Take a look at Ted Weber's 6S100 schematic and you'll see changes (or improvements if you will)....different tone stack, added presence and master volume, etc. Lots of ideas borrowed from other amp designs, but adapted to a push-pull KT88 output section. So I think Ted's approach was much like the one you propose, build upon an existing, classic design. That's really been the history of vacuum tube intrument amps in my opinion. Keep us all posted on your progress; I think this is a cool idea. We'll all be very interested to see what you come up with!
Ryan>
Thanks for the input, Ryan. I guess I wasn't clear, when I said " knock off Conrad Sundholm's original idea" I
meant his idea to shove a Mark III in a box with a modified PAM-1 for bass guitar use.
A true masterpiece of ingenuity, IMO!
While I'm no EE, I have spent considerable hours studying and playing with amplifier circuits. I have several '67-'70 100S and 200S amps as well as a split chassis Sunn for test reference, and I'm pretty familiar with the Mark III. I built my first and second Dynakits in the early 70's for my home stereo. My buddy's Dad had a pair of McIntosh MC60's and
they were the grail, this was my "poor kid's" version.
The availability and pricing of parts (particularly the Triode iron) weigh heavily in my 200S "clone" concept.
As far as legal issues with Dynaco, I've always assumed that Conrad used Dyna
kits and not factory built Dyna
cos for the early amps, and if that's so he essentially just bought
parts from Dynaco; not a manufactured amplifier. I'll bet it's an interesting story none the less!
Regardless, as you inferred; Ain't nothin' new in tube amp design. It's pretty much "fair game" from a proprietary design perspective.
I've got rough circuit design sketches and notes ranging from near stock 100S, to 100S/200S hybrid tone stacks, to modified beyond recognition circuits. It's easy to get carried away, IMO much of the beauty of the original Sunn gear was in it's relative simplicity.
Truthfully, the
amp is the easy part. The hard part is accurately gauging public acceptance and advance marketing planning to avoid a fiscal "black hole".
My
right brain is ready to commission chassis and boxes, but I'm old enough and wise enough to realize that if I can't reconcile my
left brain with it, this idea won't get past the "talking" stage.