Homage to Atchley, Kinman, and more

[ssstonelover]

Hi guys,

This will be my first post, so hopefully I won't make too much of a hash doing it.
Here are renderings of 'quieting the beast' in several versions. I know it's kind of a basic building block, but I wanted to illustrate it in a comprehensive and easy to follow way, paving the way for more newies to get involved.
The idea is to use this in conjunction with the text from "quieting the beast", which is generally excellent, gives cap values, etc.-- so the illustration would not get all clogged up.

The version I've implemented used Chris Kinman's K7 blending (all 7 pup parallel combos), master tone, and treble bypass scheme. The only difficulty I had (outside of correcting a crossed wire) was the way the blender worked adding the neck pup, but adding a capacitor got rid of the mud, so there some kind of interaction maybe coming from mixing the shielding scheme with Kinman....the fact I used a 'load' rather than no-load pot, or whatever. I'm no EE....so you guys can figure that out and let me know.

Let me know where you see errors. In particular the one on the extreme left, kind of a mix between one of Atchley's schemes married to 'Carvin' is a little dublious looking to me since I have not tried it.

Thanks to Sumgai for showingg me how to post images.

SSS Tone Lover

[sumgai]

ssstonelover said:

......
Thanks to Sumgai for showing me how to post images.

SSS Tone Lover

Oh, great.... blame me, why don'tcha? ;D


(EDIT: Post left in place, but edited to remove mention of previously oversized image, and suggested recommendations for correcting same.)


sumgai

[ssstonelover]

Hi Sumgai,

Noted I need to reformat the drawing, and this should not be too hard. It's broken down into various layers which can be moved around.

[sumgai]

stoney,

And it looks good too! Nice and clear, it should be very helpful to many of our members.

Thanks, and +1 for you.


sumgai

[ssstonelover]

Wow, worked like a charm. Original was made in Illustrator and exporting out was a hassle, for the reasons you mention Sumgai, even on my monitor which is 1920 pixels wide.... so the final fix was 'saving for web' 16 color GIF directly from Illustrator. I also reworked the font size and 'thickness', which is all for the good.

[ssstonelover]

I generally prefer vector art, raster images can never be as razor sharp... but this ain't half bad (finally)

[sumgai]

stoney,

I think I see a potential problem........

When one looks at the first "view" below the main diagram, one sees the Bridge grounding scheme. That looks like a single piece of wire (from the Bridge) is screwed down to make contact with the copper foil. Since the diagram does not show it, a viewer can potentially think "this screw goes to the shielding separately from the main grounding terminal".

That's not necessarily a ground loop, but it's also a not-good wiring practice. The reason being, the grounding effect of the strings/Bridge depends on the shielding material for conduction of the hum/buzz away from the guitar. That signal path will be a few ohms at best, but nonetheless, the resistance will exist, hence the full effect is not realized.

Better would be to show that wire as going to the same grounding ring that you show in the main diagram. Which, by the way, appears to be waving around like an antenna. You don't indicate that it's supposed to go under the volume control shaft, thus creating a good electrical connection to the material.

My whole point is simply this: if we're gonna promote star grounding, we shouldn't do it only part-way, right? ;D

(And not to put too fine a point on it, you show several black wires connecting to that ring from all angles, but only one of them hooks directly to the "soldering tab". One could suppose a viewer might make the correct inference about the electrical connections, and then hook things up correctly. However, you are showing something that is essentially a real-world picture, only without the photography device. The not-enough-coffee-this-morning crowd might perceive that they are supposed to solder each wire to some individual point around the washer's ring, and not to the soldering tab. Electrically that'd be fine, but mechanically that'd be a mess. )

...................

Last thing, really minor....... you might include a note below the three bottom diagrams to the effect that the cap and resistor values are nominal starting points, and some experimentation may be beneficial. Just a thought, like I said, it's minor.

HTH


sumgai

[JohnH]

sumgai said:

Better would be to show that wire as going to the same grounding ring that you show in the main diagram. Which, by the way, appears to be waving around like an antenna. You don't indicate that it's supposed to go under the volume control shaft, thus creating a good electrical connection to the material.

sumgai

Looking back at the QTB, it seems that it was JA's intention to have the star ground ring connector floating, and grounded to the shielding only via the safety cap, as in this pic



The other end of the safety cap is on another ring connector beneath a pot shaft, as stone has it. (This is the bit where my view is, instead put the star ground directly under a pot, and if you have a safety cap, use it just between foil and bridge grounding to protect the strings, assuming plastic knobs, to get that cap out of the main sugnal path)

John

[sumgai]

John,

Point taken, which points out all the more my apprehension about stoney's first (second) iteration. I see now that he's modified the drawing to alleviate my concerns. But I still contend that the shielding material should not be the conductor for the Bridge grounding connection - that wire should go directly to the end of the capacitor that goes to the terminal under the (tone) pot.

Seems like small potatoes, I know, but if one lets a small detail pass through like this, how long before the more important details are overlooked or just ignored altogether. This is one time that it's best to stick to the plan, IMO. ;D


sumgai

[ssstonelover]

Hi John and Sumgai,

I had a ~3 hr power outage last night after I posted the revised diagram, but while i was posting my reply..grr.. Anyway you can see what I've done, which is the important thing.

My next project will have switch rash, with some exposed metal flip switches and the PUPs will be metal 'lipstick' Danelectro type with hot/ground/shield triple wires in a S-type body, so the issue of the safety cap is of more than idle curiousity. As I understood it, the JA scheme takes care of that (and pretty deftly in a single location), but these new versions won't (though they are clean and at least take care of strings and bridge exposure), so leave something to be desired, and I don't want to create another spaghetti tangle of wires just to loop them (PUP shields and swiches) behind the cap....with the string wire, so the JA location seems vastly superior, with switch bodies directly on the shield and PUP shilelds which I would attach to a pot or loop under a switch...

Opinions?

Bill

[sumgai]

stoney,

I think I understood what you said.......

The essence is, anything mounted to, and thereby making a good mechanical/electrical contact with, the pickguard's shielding material will be protected via the capacitor, just as are the strings. That is, presuming that the shield is indeed going through the capacitor and then on to ground proper.

General comments to one and all:
Anything that is metallic and touchable while playing your axe, it must be connected to the un-grounded side of the capacitor. Before you re-assemble the guitar, check with a meter for continuity between where you can touch anything metallic, and this un-grounded point. That includes the shield (both cavity and 'guard), the pickup covers, switches, knobs, (plastic parts excluded, of course), and especially any and all mounting screws.... in short, everything except the output jack's mounting nut.

Let me reiterate that last bit.....Again before you button 'er up, you must make sure there is no continuity between the aforementioned metal parts and the nut of the output jack. If there is, then your capacitor installation has been compromised. Fix it now, before you act like a fuse during a performance on a stage somewhere! The most common mistake here happens when a jack is mounted on a pickguard, and the installer forgets to clear away the shielding before the jack is mounted. That forgetfulness shorts the capacitor, and the rest is easily guessed. The cure is simple, and needs no additional explanation here.

The caveat for this lesson is, no matter what you do, there is no way to make the jack's mounting nut safe! This includes the Strat's separate jack mounting plate, being metallic (and conductive) itself. Well, there is a way, but it's not recommended. You can use a plastic jack with its plastic mounting nut¹, and wire the internal connections accordingly. But short of using such a part, this area of the guitar is always at risk for you - don't touch it if you can help it, when operating under potentially unsafe conditions.

HTH


sumgai

1. Not recommended because all plastic jacks are cheap and shoddy - they will fall apart on you just when you need them to be on their best behavior. It's not worth it!

[ssstonelover]

Sumgai,

I made one more alteration at the bottom which should address the twin concerns concurrently:
-protection from DC shock on ungrounded side of the capacitor for any/all metal parts attached to the shield
-reduction in ohms for string ground, low that it is....to get as low as possible

I run a GFCI (ground fault circuit interrupter) from my house wiring to my amp (3 prong plug) for additional safety margin (at least under some shock conditions)

[sumgai]

stoney,

Sumgai,

I made one more alteration at the bottom which should address the twin concerns concurrently:
-protection from DC shock on ungrounded side of the capacitor for any/all metal parts attached to the shield
-reduction in ohms for string ground, low that it is....to get as low as possible

I run a GFCI (ground fault circuit interrupter) from my house wiring to my amp (3 prong plug) for additional safety margin (at least under some shock conditions)

Houston, we have a problem.......

(EDIT: problem was mine, a run-of-the-mill rectal-optical inversion, as usual. Paragraph deleted to avoid confusion, correction and apology posted below. Nothing to see here folks, let's move along now, shall we?)


And FWIW, going from the star ground point to another point (the volume pot), then onto the jack, that's a tiny violation of the Star Ground Rules, isn't it? I know, it was easier to draw it that way, but this is a real-world picture, and it should reflect what JA said, no?


And yes, GFCI devices are always a good idea! ;D

HTH


sumgai

[ChrisK]

I generally prefer vector art

Man, you must be as old as I am (I was at the celebration when we invented agriculture).

I do have one minor quibble in that you seem to have the pickups mounted on the wrong side of the pickguard. While this will effect RWRP, there is some subtle signal loss involved..... ;D

Seriously, great drawings!

[ssstonelover]

Hi Sumgai,
--So, this begs the question: where to put the safety capacitor so it protects any metal parts sticking out of the pickguard and simultaneously protects strings/bridge? Ideas?
--Volume pot: hm....Ok, I could do that.

Hi ChrisK
--thanks fgor the kind words and yeah, I know, pickups upside down, but they sure look prettier that way! Easy enough to change as all I got to do is delete some lines...
--As far as old, I was there when fire was invented, ha, ha! Seriously though there are many good design/drawing programs, so I guess we gravitate toward the ones we know.... and Illustator is cool, though certainly it had to be "worked" for this application.

Bill

[sumgai]

stoney,

You caught me sleeping at the switch! Indeed, the Bridge ground wire is going to the correct place, my mistake.

Of course, this is good for the lowest of the three detail drawings as of this moment (you do tend to update the same drawing, and that's a good thing, but it's also confusing to late-comers who haven't seen the earlier incarnations). If you replicate that lower detail view to the rest of the system, I think there'll be no further doubt as to how to do it correctly. ;D

Your notes seem to be pretty complete, but you might incorporate them into the text below (or above) as well, so they're all in one place. A bulleted list is a good way for a first-timer to "check off" each step along the way, to be sure they're getting it right. Just a thought.


sumgai

[ssstonelover]

Hi Sumgai,
Neat little trick you have there of editing prior posts, and something I can learn from.

...So you're saying the bottom drawing is good, plus the main drawings and insets are good. Thanks.

This leaves the 2nd and 1st detail drawing (from bottom). From what I can see, cap takes care of the main problem, bridge/string. Other metal parts grounded to shield w/o cap)... meaning as long as metal is not poking out of the pickguard and if pickguard screws are not touching the shield material, they would be substantially correct, ...though... still better to use the bottom scheme to cover all the bases, and leave little/nothing to chance.

So, if this is all true, I can delete those 2 drawings as unnecessary, unless you see some reason they should still be here, and instead implement your last suggestion, take the wire going back to the jack straight from the star point, skipping the connect to the volume pot... Hm....

I like the interplay, I'm learning and I think we're getting some solid info out... and I'm eager to post my next wiring diagrams.

[ssstonelover]

Oh, did not see this post from you Sumgai, and the points are well taken, so I'll add some more editorial (possibly) with dates so they know they are looking at the 'final' product.

[sumgai]

stoney,

I don't see the two upper of the lower three details as "unnecessary" so much as confusing to one who has read JohnA's original QtB article. He's pretty adamant about how to layout the wiring, and for his reasons, I concur wholeheartedly. However, electrically speaking, and from a practical standpoint as well, your "strings > cap > screw into shielding" image is also safe. If I had to rate them side-by-side, I'd say JohnA - 99%, yours - 98% safe. (Both of you have that cursed jack mounting plate problem )

It's all in the perspective of "what am I touching when the amp takes a hike in a southerly direction?" Not real likely that the player's hands will be anywhere else but the strings, eh? All we're trying to do here is to cover as many bases as practical, and that's the key word, practical.

You said "screws not sticking out of the pickguard"..... that's tough to do, unless you cut away the shield from the switches and pots, and perhaps the pickups. A better way to say it is, that's not as practical as simply mounting everything normally, and using the best wiring practices.

And yes, again according to the Gospel of John(A), you should run the volume ground to the star point, then everything from there goes to the jack ground.

I'm sure you've deduced by now that I am a safety-holic, and while this Forum is under my auspices, I intend that no one goes away confused on any safety issue. If I seem to be harping on something/anything, don't let it get to you........ and if you are truly confident that you've covered your bases (you've done your research and can cite good sources), then stick to your guns - I'll back off when appropriate. ;D

.............................

Yes, editing a post is a wunnerful thing! The downside is that sometimes a conversation takes a suddenly wild turn, and a new reader misses something vital to the following responses. That's why I (usually) add a message about what I edited. Please make a note of it.

HTH


sumgai

[ssstonelover]

Hi Sumgai,

REF: I don't see the two upper of the lower three details as "unnecessary" so much as confusing to one who has read JohnA's original QtB article.
--OK, I will kill them. Why be 98% good when 99% is possible?

REF: (Both of you have that cursed jack mounting plate problem)
--Planet Waves makes a guitar cable with a kill switch, so you can put the cable in the guitar jack "silently", then switch it on. That should ratchet safety up ever so slightly. Also the guitarist could plug in with amp on "standby mode" then flip on the "engage" switch.

REF: practicality
I'm with you on that all the way, and subscribe to the KISS principal (keep it simple stupid)

Ref: And yes, again according to the Gospel of John(A), you should run the volume ground to the star point, then everything from there goes to the jack ground.
--Hm, That does not seem to be what JA shows... he has star>volume>jack. No idea as to the motivation. Simplicity perhaps?


Bill

[sumgai]

stoney,

I wasn't aware that John hisownself violates his own credo! Be that as it may, it was either for simplicity of the drawing, or he just plain suffered a Senior Moment, one of the two. His description (in the text) carries the correct message - all grounds go to one central point, and that is the only thing that goes to the jack's ground lug.

As for that fancy plug-thingie that auto-shuts off........ how is that gonna protect someone who's touching his Strat's jack mounting plate at the magic moment? Answer: it won't. That, and your follow on suggestions deal only with the issue of unwanted noise when plugging/unplugging a cord into/from one's guitar. I do presume that your point is, this is the only time a player might be touching his output jack - but 'tain't necessarily so! Take my word for it, he/she'll find a reason to touch it during a performance, valid or otherwise.

Gotta remember also, all of this discussion is predicated on the player touching something else besides his/her guitar during the critical moment. If that contact isn't made, then the magic moment may well "come and go" without being noticed, until the amp starts failing the environmental test (it goes up in smoke). Yet another reason to leave well enough alone at 99% protection - the other one percent we can leave to the player's risk aversion of not touching anything else unless absolutely necessary.

I think you're golden there, pal! ;D


sumgai

[ssstonelover]

Hi Sumgai,

Here is a cleaned up graphic file, incorporating all the good points. The bottom image should be the golden one, with the best solutions to date, attributions to you for the improvements over the already good Atchley schematics. I'm sure you'll let me know if there are other imporvements, but I think it's about as far as we can take it currently.

Bill

[sumgai]

stoney,

You're good to go there, buddy! ;D

Post that final drawing to the Schematics sub-Forum, and give a synopsis of what you've done and why (just like your first post in this thread). Be sure to mention that this is a now a final product, and that any questions or other discussion should be referred back to this thread for resolution. That way, hopefully, there won't be any repeated comments and/or viewpoints.

+1 for your work and dedication! ;D


sumgai

[JohnH]

Thats a fine piece of work and a very useful reference. +1 from me!

On the schematics post, how about adding a direct link to the QTB article?

John

[ssstonelover]

Good idea; link now added.

Thanks for the kind words John. Your own schematics are very impressive and advanced and inspring me to my next project, already on the workbench....

Bill

[sander]

I have a question concerning pickup cavity/pickguard shield connection to the ground - I don't see any wire there and the ring connector is supposed to be insulated from shield... The only wire I see goes, as I understand, to the bridge cavity...

My second question is about mid tone pots connection to the ground. In the "separate caps" variant both are grounded independently. In the "shared cap" variant only neck tone pot is connected, while stock non-shielded guitars have both these pots grounded... What's the point then?...

[sumgai]

sander,

I have a question concerning pickup cavity/pickguard shield connection to the ground - I don't see any wire there and the ring connector is supposed to be insulated from shield... The only wire I see goes, as I understand, to the bridge cavity...

Indeed, the c/p shielding is insulated from ground...... with a capacitor. This works to provide a complete circuit for our pickup signals (capacitors pass AC), but it blocks any potential harm from a misbehaving amp (capacitors block DC). Look a bit more closely at the diagrams, you'll see a capacitor coming from the star-ground point, and going to another ring mounted underneath a tone pot (the dashed lines). I'm pretty sure that's the connection that you're missing.

My second question is about mid tone pots connection to the ground. In the "separate caps" variant, both are grounded independently. In the "shared cap" variant, only neck tone pot is connected, while stock non-shielded guitars have both these pots grounded. What's the point then?

Your question is a bit murky. In both cases you mention, the tone pots are not grounded at all! The fact that they connect to the shielding foil via mechanical contact is not of concern to us here. In fact, the neck tone pot that makes contact with the ring (mentioned above) is acting merely as a clamp to hold the ring firmly in place, ensuring good electrical contact with the shielding foil - that's all it's doing, I swear!

The important part to consider is the fact that each time you see a capacitor, one leg is coming from a pot's terminal, the other leg is going to the star-ground point. As far as I can tell, there are no variations on that theme, in these drawings. (The single capacitor variation 'shares' it's incoming lead between the two pots, that's an acceptable wiring practice.)

What other manufacturers do is up to them, of course. But I can take a guess, and that is that they tend to use the pot's shell as a convenient ground point. In such cases, you'll see either some rather under-qualified shielding material making electrical contact between the two pots (and everything else), or a piece of wire soldered to the various pot shells, which then ties them to the ground lug of the output jack.

Electrically it's all the same, until Mr. Murhpy decides to twitch his little finger, and the unforeseen becomes all too clearly seen. (As in, your amp blows up, trying to take you with it. ) That's when attention to details like this come into play, I'm sure you'll agree.

HTH



sumgai

[bluesman13]

Hello,

I was reviewing this thread as I am planning another build and noticed something that I missed before. Previously, I had the trem claw grounded only to the shielded body cavity (figure 1 in the original QTB instructions), but it appears in this diagram that prior to connection to the vol/tone pot, there is a wire going from there to the the trem claw? Am I seeing this correctly. I'm no electronics expert (or electronics anything for that matter), but I don't see how I could've missed this previously. And, I don't mean to over-simplify, but all of the guitar (pickup grounds and pot grounds) grounds go the "ring terminal", then the capacitor, then to another ring terminal which attaches  to the tone/vol pot, but then another wire after the capacitor goes to the trem claw, so there is no wire from the trem to the body of the guitar? Thanks for any assistance.

[newey]

bluesman13-

The trem claw is connected to one end of the "safety Cap", and the other end of the cap is wired to the ring connector, which in turn grounds the pot shell and trem spring through the pickguard shielding, via contact with the ring connector.

The use of the so-called "safety cap" (which at best might lessen shock hazards in very rare scenarios) is really optional these days. A modern amp with 3-prong AC cord doesn't present nearly the same risk as the old tube amps did. I play at home, and I know my outlets are properly wired. I don't include the cap in my builds. But if I was likely to be playing in places where the outlets might be dodgy, I'd probably put it in there.

But it is not, to be clear, connected to the lugs of the V pot, it is only being grounded to the shell.

[bluesman13]

Hi newey,

thanks for your reply,

I've attached a screen that has a wire going from the vol pot lug to the ring connector - is this incorrect? I tried to make a black line around it...

I think I've done that in my original build. The only difference I can see is that my trem law is grounded in the shielded cavity, and the neg wire for the output jack is attached to the same lug on the vol pot as the wire that goes to the ring connector.

It appears to me that i need to move the output jack neg wire to after the 'safety cap, and attach another wire after the safety cap that goes to the trtem claw ground wire? does that sound correct. This stuff is hard to explain so I appreciate your assistance.