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Discussion in 'Shock Brother's DIY Amps' started by dunehunter, Feb 9, 2019.
Thanks @King Fan. Glad to see you here!
mm? You lost me.
Where are you from?
Well, after a day of prep and a day of colonoscopy from hell, I'm back now...
So here's a quick question before i get off on soldering the rest of the board. @robrob has two grounding schemes shown for the 5F1; one shows the Power Tube cathode resistor/cap and everything "south" of the input jack grounded to the power rail; the other, shows the entire preamp circuit grounded at the same rail as the rest of the preamp section. I was just kind of blindly following the first scheme listed but now not sure that makes sense.
Hee's ground scheme #1:
Which actually makes more sense to me...
BTW, I don't know how to put, like circles and such on graphics yet (PowerPoint, perhaps?) but the place to look is R6, V1B cathode resistor.
I know both would work but I'd think separating the preamp section entirely from the power section makes the most sense--and noise-"free" operation to me.
Glad to hear the procedure went well.
Is there a problem you're still trying to solve at this point or just looking for improvements?
This is my favorite software for basic editing if you want to try drawing circles. It's a more advanced version of the old school Paint program:
Is there ever a good day with a colonoscopy? I guess one where everything looks as it should.
Paint dot Net (Paint.Net) is fantastic and free. GIMP is, too. Both require a learning curve, though, and are more like Photoshop than the old MS Paint.
Paint still comes stock on Windows, and is easy as pie to do simple shapes and texts over pics and the like. @robrob's pics are PNG. No problem to add shapes and texts with Paint.
EDIT: sorry for the $hitpost. I'll go away now.
Scheme #1 is a more true preamp / power amp split grounding scheme. If you follow the signal path, C2 is the .02uf coupling cap that transitions from the preamp and power amp. R9 is the 6V6 grid leak. R8 and C6 are the 6V6 cathode components. That's your power section. Grounding it over by the power section ground joins those components with their corresponding filter caps C3 and C4.
Scheme #2 looks more like grounding to the closest and most convenient location in terms of proximity. Kind of a lazy choice that may sacrifice 'most optimal grounding technique' in an academic sense.
All that said I've heard and built many fairly quiet guitar amps using sub optimal techniques. Guitar amps are very forgiving in this sense. Leo's old designs aren't really 'academically correct' in many ways. The stratocaster has ground loops in how the back of the pots are wired. In most of the amp designs things like input jacks, output jacks, and pots aren't isolated from the chassis producing a double ground possibly creating a loop. Using an eyelet board and spacing tubes the way he did creates fairly long runs from the input jack to V1A's grid with no use of shielded wire. The technique you use for filament wires can be very impactful as well, and if they're center tapped.
I don't think it is wrong or bad to try and optimize your grounding scheme. Just know that it is one variable among many.
So, yeah, the problem is the two different grounding methods...although I've pretty much made up my mind to go with GM 2, above.
Thanks. I was wondering if the power tube should be joined into the power rail. That was the path that I was going down first when I saw that additional grounding scheme and thought..."wait a minute..."
Again, my first build; just trying to dot all my i's and cross all my t's. And, as I said above, each method should work. And you are probably right too that Leo was NOT particularly careful in his grounding scheme and it worked anyway
Wha...? Come back!
Oh jeez, that one went right over my head LOL
Must be the anesthetic
I used Paint to graffiti robrob's pic to show how easy Paint is to use. It was unnecessary and kinda bad taste. I deleted it. Didn't write anything offensive, though. Just really off topic and silly.
America. Let's see, in Minnesota units, 1mm = 0.0007952 rods, 0.0001988 chains, or 0.00001988 furlongs.... ;-)
Sent from my iPad using Tapatalk
I love "the rod" as a unit of measure. Seems like we only used it when putting up barbed wire fencing...