One board amp

[dynaman]

Damn, I've been fiddling with something like that. So much for originality. Actually, I remember seeing some pics of a neato amp at 18Watt that was similar to what you guys have shown pics of and that's where I got the idea. Sure wish I would have saved the pics, cuz I don't frequent that site anymore.

[Andy Le Blanc]

It's nearly a standard for most new tube amps, just not usually associated
with point to point. You start with the old fender layouts, everyone been in an
old fender, but there are a variety of ways to put a circuit together.
I remember a real old danelectro, real P-P and calling it a birds nest doesn't do it justice.
Every type of build and layout has its pluses and minuses. I've been in a good
pile of old amps and put in enough noodle time on the bench that I'm not
afraid of mixing metaphors. P-P pcb with terminal strips, fun stuff.

[ampdoc1]

I've had some thought on this kind of board as well. I prefer PCB, but this has about the same advantages as the others here. I'm going to use PCB 12ax7 sockets with a shield, so I can have the base screwed down to the board.
I also want to use this as a design "platform", so I'm going to install 45 deg angled Phoenix connectors to mount the major caps and resistors (seen as the rectangles with 6 holes on the board).
All the high voltage traces are double sided, and all component mounting holes are plated through, and sized to accept eylets.

I've also laid out a pair of boards for the controls that eliminates most of the wiring between them, leaving just a few going to the amp board (I had to divide the boards because PCB Express doesn't make boards longer than 14).

Not the cheapest way to go, but each set of amp/EQ boards will be just a little over $100.

[Andy Le Blanc]

second test fit....

with "tubes up", looks like convective cooling be nicely effective.

[paulster]

You're not going to have any flex in that board to worry about!

[Andy Le Blanc]

Make it strong enough, then double it....
I fab'ed the stand offs from 1/2" aluminum round stock.
Actually cheaper, and it gives you control.

[Structo]

You guys are going all high tech and stuff!

I kind of like the method that HAD did on the SSS.
Mount the sockets to the chassis, then have the board about ~ 1/4" above with holes cut into the board. Then solder short jumpers from the board to the socket lugs.

Although with that thick of board your way is just as good because you are not relying on solder joints to mount the sockets.

[dano-rator]

Meh, I'd have gone 1/4-20 grate 8 on the standoff bolts, but I guess it'll work

Just kidding - that setup looks RIGID! Good luck w/ the quest...

Dan

[Wayne]

Looking sharp so far, Andy. With proper attention to technique in mounting the smaller components, an amp built like this should be bulletproof x2!

Are you planning a separate board for the power supply, or are you placing each dropping resistor/filter cap near the appropriate stage?

You could make this idea more modular by making smaller boards, one for each socket, rather than one big one. Each board would need 4 external connections, and troubleshooting would be reduced to finding out which stage had the problem and replacing that board. Another option that opens up is the ability to quickly swap in differently voiced stages.

Just a couple of $.02's

W

[Andy Le Blanc]

I use the "bounce around in the back of the truck" test, its not quite as severe
as the "hit the pavement at 45" standard.

The hope is that it does have layout flexibility, thanks for the two cents.
I think it should enable customization to a degree, half dozen different pre,
tone, inverter, gain module etc... but its more important to be able to do all
the fabrication on the kitchen table, rugged stupid simple.

Besides If your gigging out 3 or 4 nights a week you beat the tar out of your gear
and at 3 am after a night at the bar hanging out the parking lot you aint
gonna want to give a damn about slamming the crap into truck before you split.
There's a reason old tour gear was so rugged.

I think I'll have some filter caps on the board, and a separate can.
The layout is still evolving, I screwed up, I didn't give my self enough
room for the fuse holder between the chassis and board, per my original intent.
But decided to use the hole for a hum pot make another hole and move
everything over one on the back. Still evolving. I know there will be a
few more little design crisis like that to work through before completion.

[oldepicker]

Probably obvious, but I'll offer it anyway!

When building a new amp regardless of style, unless doing a true clone, generally we build from outside in, the obvious advantages being you don't have to move a board or major component because you forgot something in the planning/designing process.

That being said, the best way to do this type of thing would probably be to mount all your outside components first... pots, switches, lights, jacks, power... then transformers and power supply components (electrolytics and rectification are bulky but can be stuck in less desirable real estate in the chassis (keeping noise interference and the like in mind). Only then should the "mother board" location be decided upon.

Doing the board location first inevitably leaves you saying to yourself " Oh shit, I forgot about that!"

[Andy Le Blanc]

yep, the flow on this one is different.

But you have to be fear less. I have made those base assumptions.
I'll see if I screw my self into a corner. I've done the fender layout for 20 years.
It's accessible, easy to replicate, so much so that it's hard to find anything
clone to custom, new or old, that isn't really just another fender at heart.

Boring, do something different, take a risk.

You've made a very good point, most design assumptions that end up being
used are completely backwards.

The primary issue in my mind with this one was to work around this component
board with this placement as the primary design feature. The decision to
make the dash board as clean as possible by placing power components
on the back was secondary decision, it wasn't a bad choice and compensating
the layout wasn't a difficulty. But.... I'll be the first to know if I've
screwed the pooch a little further on. The plus side is that its not a real
issue for me to fab up another with a corrected layout.

[flood]

those are fantastic guts. i'm building my soldano atomic 16 clone using FR4 (only 1/16", sadly) as an experiment, but not as a one board amp - the sockets are chassis mounted and there is no PCB for the power section.

i am a bit pessimistic about the way this build will turn out over time (bombay is hot AND humid), but i figure i can just swap it out with a little effort for turret or tag board if i think it necessary.

i think the biggest problem with PCB amps is the serviceability factor - a friend of mine has a problem with his bogner ecstasy. he lives in delhi and has no idea as to how tube amps work in general. i think it's a dead regulator. this would mean getting the whole damn board out to desolder parts. shipping from delhi to bogner is risky and bloody expensive too.

this board is a lot easier to work with, if there is one provision i would make, it would be to keep the power supply board separate OR have a removable plate above the solder side of th PSU for easy cap changes as and when the time comes.

[flood]

preliminary shot of the atomic 16 guts... will be giving this little guy his own thread once i'm done and know the results.

the preamp, FX loop and PI components are all mounted on PCBs, as you can see; the unnpopulated PCB at the back is for all low level DC circuits - relays, LEDs, and dual triode heaters all being fed from 4 7806 regulators. also on that board is the bias supply. i had a little extra space, so to save etchant and etching time, i just drilled a bunch of holes in the copper. was initially thinking of using it as a pseudo-star ground but have decided to grounding to the chassis on one of the fat bolts holding the trannies down.

this is my sixth amp ever and my first time using PCBs in an amp or in a high voltage situation - i hope it works out ok, and that my knowledge from laying out ECG front-ends somehow percolated through and made itself useful here. comments welcome.

i'd love to try a one-board amp sometime but i think i still have a VERY long way to go - i'm 28 now, i suppose i have the time

PS: yeah, i screwed up on the drilling and didn't really plan much before building - it was initially supposed to be point-to-point but i guess i kind of went overboard with the EF86 input boost stage and the FX loop. will start a new thread somewhere.