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Hi all,

I finished my build last night and its great apart from a bit of hum that I seemed to have cured with the preamp shields. I'm just wondering though if the volume pots are wired correctly? In the diagram it has a wire connecting the first lugs but then talks about wiring the back of the pots and shows a picture like what I ended up doing. Just wondering if what I did was correct? All seems to work normally.

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Gear Demos
http://youtube.com/martys13

The ground buss on the back of the two volume pots is redundant in your case, since you've wired the two #1 lugs to the ground tab of the lower bright channel input jack. Though it may not cause a problem, it does create a ground loop (i.e. parallel ground paths) for those pots and that jack, and such loops can cause hum. Personally, I'd remove it.

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“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Oh I see. Does that mean the instructions are wrong or misleading? It talks about wiring the two number 1 lugs and then also says to solder the back of the pots. Then wiring up it shows to solder up the ground on the bright channel.

So I should remove the buss on the back of the pots completely?

Edit: would removing the white wire from lugs 1 to 1 achieve the same thing? Its a bit easier than taking off the buss wire. I'm thinking not because it would still be grounded through the pots and the input jack.

_________________
Gear Demos
http://youtube.com/martys13

I would just cut that white wire loose, would be the easier of the two to remove. Hell, you could even remove the buss wire too since the two pot casings are connected to ground through the chassis to which they are bolted.

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But then the lug 1's wouldn't be grounded right? If I removed the wire and the buss

_________________
Gear Demos
http://youtube.com/martys13

you would still leave lug 1 connected to the pot body in that case, you just wouldn't need them connected together.

_________________
If practice makes perfect, and nobody is perfect, then why practice?

It hurts me to say this.. but.. follow me on facebook and.. instagram

Don't do that. If you do, the signal now has to go through two mechanical connections (pots/chassis, jack/chassis) which could loosen in order to get back to ground. You're also now mixing signal ground with a shield ground.

The instructions are confusing because the sketches are consistent with standard amp building practices, the pictures are not. There is no need to have the bus wire across the back of the pots, because as has already been mentioned in an earlier post, the pot casings are being grounded to the chassis by their pot lugs. The casings are just a shield, so if they lose ground, the most that might happen is you get a little more noise, but the amp will work. There are times when you want to run a bus wire across the pot casings (like if you have a plastic enclosure, or a pot that's not mounted to anything like when testing a circuit), but this is not one of those times.

Completely remove the bus wire, leave the white wire. If you don't want to get in there with a soldering iron, just cut the length of wire between the pot lugs and the casings. Enjoy your amp.

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-Mike

^ This. I have my TR wired this way, and it's quiet and has never given me a hint of trouble.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Very good points Mike. Another one of those times where theory and application don't jive.

Yeah, do what he said.

_________________
If practice makes perfect, and nobody is perfect, then why practice?

It hurts me to say this.. but.. follow me on facebook and.. instagram

Cheers guys will do!
Maybe its time for a new instruction revision? I can't be the only one that's done this.

_________________
Gear Demos
http://youtube.com/martys13