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Post by LTB on Jul 14, 2020 17:50:58 GMT -5
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Post by Peegoo 🏁 on Jul 14, 2020 20:06:56 GMT -5
Lindy makes some of the best pickups in the universe, but I disagree with the writer's points on star grounding. Star grounding is important in amps, but not in guitars that have passive pickup circuits.
The reason is amps contain various voltage levels that create variances between ground reference (potential) across the separate stages of the amp circuit. Star grounding here prevents ground loops where stray voltages can run in a loop through separate ground connections and create noise in the signal.
In a passive guitar there is only a single ground reference (all ground connections are always at the same potential), and a ground loop is not possible.
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Post by LTB on Jul 15, 2020 5:38:40 GMT -5
Cool perspective Geno!
Thanks
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Post by Peegoo 🏁 on Jul 15, 2020 6:48:28 GMT -5
It certainly doesn't hurt to star ground a guitar circuit; that's why it's still a thing, because it works just as well as series grounding. Which is weird, because even though Delsack states Lindy prefers star grounding, he shows series grounding in his article as an example of good practice:  Star grounding actually looks like this:  A simpler comparison:  I know this seems like nitpicking, but there is a huge amount of unintentionally misleading and confusing information on the Weirdwide Web. |
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Post by funkykikuchiyo on Jul 15, 2020 9:18:26 GMT -5
I agree with Peegoo wholeheartedly. It is based on the idea of ground loops, but it is virtually impossible to get a ground loop in a passive guitar. The only time I've ever seen a ground loop be an issue was when one guy had a piezo/magnetic split and was going to two different amps, but at that point the ground loop was with his whole rig, not within the guitar. The fact that grounds couldn't be fully isolated in the two pickup systems proved problematic in trying to solve the issue at the guitar, so he just had to cope and find a way to deal with it through his rig. Getting everything onto the same power circuit helped a bit as I recall.
I don't think it is nitpicking... people expend way too much energy on trying to nip a problem in the bud that just doesn't exist. It can sometimes also mean sloppy wiring. If two pots have grounds connected via some shielding or a conductive control plate, it would be prudent to also have wires soldered to the backs. The redundancy will help keep things going along if the shielding or pot oxidizes and those connections aren't very good. Those solder joints have a lower resistance than what you get with the shielding, so it might even be lower noise. Someone worried about ground loops might skip that, or go through the needless extra step of insulating the shielding from the pots. Usually when people are trying to avoid ground loops they just imagine any place where they could trace a circle with their fingers and assume it will generate noise, and that just isn't true. Take Peegoo's picture of the series grounding and add a wire between the two volume pots... it creates a circle, but it won't create any ground loops. It just adds a little more continuity. Electrons aren't hyperactive kittens that will just run loops in any area made available to them, it will only happen if there is a variation of potential or resistance to ground.
Every once in a while we fix bad wiring at our shop which someone did some at home and tried some weird wiring scheme and the end result was that they skipped a ground connection for fear of making a loop and rendered part or all of the control harness useless. One or two extra wires and the whole thing starts working again.
I've heard it hypothesized that bad guitar cables can cause noise problems to which fixing wiring schemes can help because the shield/ground on the cable might have some resistance. I never really liked that hypothesis because A) it still isn't a ground "loop", it is just a ground "lollipop" because the only ground on the guitar is the one at the jack, and B) just get a better cable, dude.
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Post by funkykikuchiyo on Jul 15, 2020 9:49:20 GMT -5
Also adding that the longer I am in this industry, the more I realize how many basic pieces of advice get passed around from person to person without ever really being put to the test. I've just been hacking away at guitars a long time, Peegoo has a real snazzy electronics background (official credentials) and is worth listening to*. As I've been learning more and more about woodworking, I'm finding that a lot of the guitar biz stuff I've heard over the years is full of feces. People in the guitar world just don't like doing real tests, they prefer either sloppy tests or appeals to authority.
*(sometimes guitar stuff can be so wonky that it takes someone with real credentials AND is a guitar tinkerer to make sense of it because they'll behave counter intuitively. To figure out some stuff via an electronics background that guitar people figure out sooner you need to get into some funky AC electronics stuff that gives grad students headaches. I know of one guitar maker that designed some special equipment for a local university, and my theory on why he was capable to begin with was because of all the weirdness of guitar audio paid off, but that's another matter. My point is a good guitar tinkerer and someone reasonably scientific is a really good combo.)
Alright. I'll stop ranting now.
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pdf64
Wholenote
Posts: 556
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Post by pdf64 on Jul 15, 2020 9:57:25 GMT -5
It’s very unfortunate, but ‘official’ site blogs of reputable MI companies have pretty much the same ‘factual to nonsense’ ratio in their content as the rest of the internet. Disappointing that no one with engineering competence checks what’s being put out under the company name.
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Post by funkykikuchiyo on Jul 15, 2020 10:13:09 GMT -5
It’s very unfortunate, but ‘official’ site blogs of reputable MI companies have pretty much the same ‘factual to nonsense’ ratio in their content as the rest of the internet. Disappointing that no one with engineering competence checks what’s being put out under the company name. I agree, except I have zero engineering credentials, but I know fully well to do some homework outside of MI anecdotes and know the difference between a good test and a bad test. I don't think lacking a degree is a good excuse. |
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pdf64
Wholenote
Posts: 556
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Post by pdf64 on Jul 15, 2020 11:39:56 GMT -5
I don't think anyone's so all knowing that they don't get into a muddle over something sometime. That's the benefit of having another pair of eyes that know the topic review such articles, and it's the fatal weakness of blogs. Here's another one, kinda funny how he constructs a topsy turvey rationale (The Quick Answer), backs it up with data that seems picked out of nowhere, but reaches the correct conclusion wgsusa.com/blog/choose-perfect-guitar-volume-pot and wgsusa.com/blog/choose-perfect-guitar-tone-pot |
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Post by Pinetree on Jul 15, 2020 13:32:59 GMT -5
I use a piece of buss wire and series ground the (2 control) guitars I build.
I also use copper shielding tape on the entire cavity under the pickguard.
FWIW, they get played at concert volume at medium size venues, and don't have any noise issues.
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