T-Riffic with 2 volume/tone stacked pots

[ethienistic]

EDIT:
Changed thread title as decision has been made as to what it is I need for the wiring of my guitar.

Jump to this post to see ChrisK's diagram for this particular modification.

ethienistic[/i]





Hi there

first of all sorry for the thread title, I just didn't know what to put there!

I am completely new to electronics, and although I have been doing a lot of research over the last few days, my head just doesn't get round some of the things I read...

I stumbled across the Guitarnuts website and that's how I got here.

Anyhow, here's the situation:

- really old guitar (1955 Gibson ES-225), which is having 2 Gretsch HiLotrons put in
- I want the T-Riffic setup plus independent volume for each pickup (that's 3 pots: 2 volumes + 1 tone)
- guitar has 3 holes (1 switch, 2 pots), and I don't want anymore


So, to the problems facing us:

(1) there's no hole for the 5way linear switch
(2) there are only 2 holes, when we need 3 pots
(3) even if I solved (1) and (2), I'd still need help with figuring out the wiring diagram...


I've resolved (1) by finding a rotary 5way switch which will fit into the existing switch hole nicely, and I thought a potentially solution for (2) could be a blend pot for volumes. I've read conflicting reports on blend pots but someone said DiMarzios were great. Any recommendations or brands I should know about?

Another solution would be to use stacked pots for the 2 volumes (à la Danelectro) and a single pot for the Tone. The only reason I am reluctant to go down that route is a purely aesthetic one: I'd like both pots to look the same, and I can't really see Danelectro or metal stacked pots (like those you can see on some Fenders) on this guitar. But again it's not set in stone, I guess I could have 2 Danelectro knobs, one being a true stacked, the other really a single but just there to match the volumes' one.

Yet another and more drastic potential solution is to get rid of the Tone pot altogether, as I *never*, and I mean *never* touch it. In that case I read somewhere thatwhen there is no Tone pot in the wiring, a capacitor should be added somewhere to make up for its absence, so as not to gain any extra brightness.


So finally, any help with working towards a complete diagram, be it any of the 3 possible solutions would be immensely appreciated. I've linked the T-Riffic setup image to help with descriptions and stuff.

Thanks a lot in advance!

[ChrisK]

There are two kinds of blend pots; the first are the pan pots sold as blend pots, and the second are the true blend pots used in active bass guitars. Blend and Pan Pots

In either case, you would be able to blend between both pickups to varying degrees, but have no overall control of the volume.

I might suggest that you use a dual concentric shaft pot such as the EP-4586-000 for two volumes in one. This way you can still adjust the relative level and the overall volume.

Using individual volume pots with the T-Riffic will require some redesign.

I recently did a design that does what the T-Riffic does but with two volumes and two tones. It also had two push pull switches per pickup for coil selection. While considerably more complex than what you need, I'll link to it since, if the push pull coil selection stuff is removed, it shows how I use individual volume pots in a series/parallel switching structure.

P-Rail Switching Scheme

If you don't "see" how to reduce this for what you want, let me know and I'll modify the drawing since it's much easier to take stuff out than to add it in.

Also note that I use a different combination sequence than John A. I feel that tonally, the N*-B belongs next to the bridge selection and the N*B belongs next to the neck selection.

Anyway, the ordering is arbitrary.

[ethienistic]

Hi Chris, thanks a lot for your quick reply.

I had indeed read about "true" blend pots as opposed to pan pots, and been recommended one at Stew-Mac that has both PUs at full volume at the center detente.

I also take your point about having no overall volume control, and although I'd thought about it I may not have fully appreciated how annoying that could turn out to be!

A dual concentric pot for the 2 volumes seems therefore to be the best idea, but it would have to 250k/250k as it's for 2 single-coils, right?

I may come back to you for help with simplifying your P-Rail diagram, I need first to find a dual concentric pot.

With regards to having no Tone control at all, should I just do the same as with 2 volumes + tone, but removing the tone pot and leaving the capacitor in the same spot to emulate a tone pot fully opened?

thanks again

[newey]

I had indeed read about "true" blend pots as opposed to pan pots, and been recommended one at Stew-Mac that has both PUs at full volume at the center detente.

Be suspicious. The Stew-Mac description of this pot uses the word "pan" in it, and the statement "full volume at the center detent" is meaningless- "full" as compared to what?

I've bought several claimed "blend" pots that turned out to be pan pots. If you do take the plunge on this part, please put a meter on it and let us all know. If it turns out to be a true blend pot, we'd all like a readily available source for these.

A dual concentric pot for the 2 volumes seems therefore to be the best idea, but it would have to 250k/250k as it's for 2 single-coils, right?

It doesn't have to be 250K, that's your call. If you are eliminating the tone pot, however, 250K would be a sensible choice. 500K would be quite bright sounding, and you'd have no way of adjusting it.

removing the tone pot and leaving the capacitor in the same spot to emulate a tone pot fully opened?

The capacitor doesn't come into play until the pot is turned down a bit, so leaving it in will not "emulate a tone pot fully opened". The pot, unless it's a no-load pot, does add some resistance to the circuit even at full open, so its removal will affect your sound somewhat.

You certainly could put a capacitor in, again it's your call, depending on the sound you want.

[ChrisK]

I stumbled across the Guitarnuts website and that's how I got here.

So it was like a speed bump or a curb and this is where you fell?


If you eliminate the tone pot, you do have some interesting options. You could use two volume pots alone, or you could use two push pull pots for the volumes.

Hmm, there be switches attached. What could we use them for? I know, to switch in a tone setting. If you almost never use the tone, have one setting do nothing (or select a 240K resistor in series with the existing tone cap) and the other a resistor value equal to the tone pot setting when you actually aren't almost never using it.

In other words, you could have four tone settings (two switches - four combinations) a la' the Gretsch tone switches.


Now, here's a possible fly for your ointment; do these pickups have a single conductor plus shield wiring? If so, there may be some issues with series and reverse phase wiring (one pickup's shield and metal cover will not be grounded, but connected to the output (reverse series), or the other pickup's output (series)).


Either way, touching the pickup's metal cover will generate some interesting "buzz-tones".

[pete12345]

Nov 11, 2008 13:54:35 GMT -5 ChrisK said:

Now, here's a possible fly for your ointment; do these pickups have a single conductor plus shield wiring? If so, there may be some issues with series and reverse phase wiring (one pickup's shield and metal cover will not be grounded, but connected to the output (reverse series), or the other pickup's output (series)).


Either way, touching the pickup's metal cover will generate some interesting "buzz-tones".

Why not just swap over the neck and bridge pickups in terms of wiring, so the neck pickup's shield always goes to ground, the bridge pickup's shield being 'lifted' for series and out of phase

[ChrisK]

Why not just swap over the neck and bridge pickups in terms of wiring, so the neck pickup's shield always goes to ground, the bridge pickup's shield being 'lifted' for series and out of phase.

Well, I guess it depends on where your picking hand tends to loiter.

I tend to loiter near the bridge.


Touching a floating cover/signal wire is touching a floating cover/signal wire.

[ethienistic]

Thanks for all the input. I've been thinking about all the info I've gathered and I think that if I'm going to go for 1 stacked pot for volumes and put two stacked knobs for matching looks (I've borrowed some Danelectro knobs from a friend and the look is actually perfect for this 50's looking guitar), why not put 2 stakcked pots and get a Volume and a Tone for each pickup?

This decision is also reinforced by the fact that stacked 250k pots are simply nowhere to be found. Therefore I'll have to go for 500k/250k (ie Volume/Tone), and so the Tone will be under one of the Volumes anyway, so why not have another Tone while I'm at it.

(It really is raining too much in this country, leaves me too much time to ponder things) ("this country" is the UK, btw!)


The Tone switch idea is fun, but I just fear that once I'd try that, if I'm not happy with the result I'll never get the wiring out again to change it, so I'd rather have a Tone pot I rarely touch.

I have already ordered 2 500k/250k CTS concentric pots from the link kindly provided by Chris in his first answer, so I'll update you on progress when they show up in 2-5 weeks time (the overnight shipping cost to Europe was a bit steep).

As for the question regarding whether my pickups have single conductor plus shield wiring, although I can't say I have the slightest idea what that means, I *can* say that a google search for a combination of "hilotron" "shield wiring" "single conductor" returned absolutely no result whatsoever, so I'm inclined to answer no they don't.

[ChrisK]

As for the question regarding whether my pickups have single conductor plus shield wiring,

This is what a single conductor plus (braided) shield looks like. The shield is soldered to the back of the pots and the single conductor (in this example it's black) goes to the switching. The shield is a shield as well as one of the coil wires. The metal cover is electrically connected to the shield.

www.seymourduncan.com/support/wiring-diagrams/schematics.php?schematic=p90

In this example, there are two wires coming from the pickup, but neither one is a shield. This can be used in series and phasing with no concerns.
www.seymourduncan.com/support/wiring-diagrams/schematics.php?schematic=single_coil_one_vol

In this example, each pickup has four wires (two per coil) and a bare wire that is a shield. This can be used in series and phasing with no concerns.

www.seymourduncan.com/support/wiring-diagrams/schematics.php?schematic=p90_stacks

[ethienistic]

Hilotrons indeed have 3 wires, white, red and braided. Thanks for the explanation ! Once I have all the components I'll have a go at a schemtatic and post it here.

By the way, would you mind having a look at the switch I bought and tell me whether it'll be suitable for the wiring I intend to do? (ie mimicking your P-Rail but with 2 concentric pots instead)

It seems to have a lot less lugs than your schematics require!

[ChrisK]

Hilotrons indeed have 3 wires, white, red and braided.

If you have the pickups at hand, measure the resistance from both the red and white wires to each other and to the shield. Use the 20K ohm scale. Post the results. The important thing is that neither the red nor white wires are internally connected to the shield.

By the way, would you mind having a look at the switch I bought and tell me whether it'll be suitable for the wiring I intend to do? (ie mimicking your P-Rail but with 2 concentric pots instead)

This is a 4 Pole 5 Throw rotary switch. It will have 6 terminals for each of the four sections (poles). This is for 5 position selections and one for the the pole common. It has 24 terminals in all.

The 4P5T lever super switch is a 4 Pole 5 Throw rotary switch turned sideways with a lever attached to the shaft. It will have 6 terminals for each of the four sections (poles). This is for 5 position selections and one for the pole common. It has 24 terminals in all.

It seems to have a lot less lugs than your schematics require!

"Seems" can be deceiving.

It's the same in functionality.

[ethienistic]

I'll manage to find a ohmmeter and will let you know.

I've had a go tonight at drawing the schematics for a 2 single-coils, 2 tones 2 volumes T-Riffic, but even with the help of the Stew-Mac tutorials and a plethora of other sites, it would be guesswork more than anything else if I tried to do it myself.

So if (and only if) you have the time, I'd be very thankful if you could reduce your P-Rail wiring for me.

I have always been fascinated by electronics, and all this reading about guitar wiring has really frustrated me, realising the depth of my ignorance

Is there a good book about the electronics applied to audio (although I'm interested in electricity as a whole, I think it best to try and focus our efforts...)?

Cheers

[newey]

Is there a good book about the electronics applied to audio (although I'm interested in electricity as a whole, I think it best to try and focus our efforts...)?

There are probably good books. What we have are some good weblinks.

"Help, I don't understand electronics!"

If you really want to focus your energies more specifically to guitar switching and wiring, our friend wolf's site is here.

[ChrisK]

[ethienistic]

hey newey, thanks a lot for the links, duly bookmarked!

Chris, again, thanks for being so prompt. I'll try to post the ohm reading of the pickups today.

[ethienistic]

A final question:

Chris, on your diagram, I see the volume is not wired to itself like I've seen everywhere else (the ground lug folded back and soldiered to the back of the pot), is that normal, or is it implied in your diagram in a way a philistine like me doesn't understand?

cheers

[ChrisK]

You certainly can do this (connect the "ground lug" on the volume pot to the case) EXCEPT on this neck volume since the case is usually grounded and the "ground terminal" on the neck volume pot isn't grounded in two of the 5 5-way positions (that's how series works).

I don't generally connect the "ground" lugs to each case since I follow good engineering practice in grounding (versus generally tolerated guitar practice). I practice star grounding.

I also rarely discuss grounding since most don't understand it and it's just a lot easier not to. What's been done in guitars for 50 years is good enough for most ears.


In this design, only the bridge volume pot's "ground" lug is always actually connected to "ground" (and only if one isn't practicing the "faith of the isolation capacitor").

[ethienistic]

rrrrriiiiight, I'll take this as a "no, it's normal" then, shall I

I'll follow your diagram faithfully. I only asked because sometimes some practices are so evident to even the least learned in a given field as to be overlooked as being too basic to mention.

[ethienistic]

I finally received all the remaining components. I just finished unsoldering all connections (my first time, funny how some just wouldn't give in, I had to cut them).

Nov 12, 2008 18:40:58 GMT -5 ChrisK said:

Hilotrons indeed have 3 wires, white, red and braided.

If you have the pickups at hand, measure the resistance from both the red and white wires to each other and to the shield. Use the 20K ohm scale. Post the results. The important thing is that neither the red nor white wires are internally connected to the shield.

I tried to take a reading of the pickups as instructed by chrisk, but unfortunately the Ohm section of my "Analogue Multimeter" only has "X10" and "X1K" scales, and the VU meter did not even flicker when I tried either of those.

So I think I'll just give it a go anyway, what's the worst that can happen ?

[newey]

what's the worst that can happen ?

The worst that can happen is it won't work as advertised.

Then, you'll need to spring for a digital multimeter to troubleshoot it.

[ChrisK]

I tried to take a reading of the pickups as instructed by chrisk, but unfortunately the Ohm section of my "Analogue Multimeter" only has "X10" and "X1K" scales, and the VU meter did not even flicker when I tried either of those.

The X1K scale should be fine. You will read about 6 to 8 on it.

1. Are you sure that you're on the X1K Ohms range?

2. Are you sure that the test leads are in the correct jacks?

3. Are you sure that the meter battery is good?

4. Are you sure that the meter battery is?


Connect the test lead ends together on the X1K range. The needle should move to "0".

[ethienistic]

A resounding "I think so" to all the above, although the battery could have been the culprit, no way to tell as my only battery tester is the multimeter itself (yes I could have got a new battery, but since I may be doing a lot of electronics soon I thought why not get a good meter) (the VU didn't move either when both leads were connected together)

Anyway I got a new ohmmeter yesterday, and here are the results:

neck PU, red + white = 3.40
bridge PU, red + white = 3.80

and for both there was no reading for either red to braided or white to braided.

[ChrisK]

although the battery could have been the culprit, no way to tell as my only battery tester is the multimeter itself

FYI, an analog(ue) multimeter only uses the battery on the Ohms ranges (to bias the resistor under test). As a result, the meter on the DC voltage ranges CAN be used to test the battery.

(the meter needle didn't move either when both leads were connected together)

I vote for a bad battery or bad leads.

neck PU, red + white = 3.40
bridge PU, red + white = 3.80

and for both there was no reading for either red to braided or white to braided.

Good, there is enough difference between the pickups that they can be discerned later if wiring issues arise.

The shield is a separate connection. Both coil leads are isolated from the shield. We can do series and out of phase with no issues.

[ethienistic]

Thanks a lot chrisk for all the help. I bought Orange Drop 0.047 mfd capacitors today, so I've got everything I need... I'll let you know how I get on. God speed gentlemen

[ethienistic]

Sorry but two last questions reg your diagram:

1. you labelled one PU lead "hot" (white), the other "not" (black). Leads on my PUs are red and white, how might I find which is hot and which is not? Is it as straight forward as "it's the white lead, because it's white and white is always hot"?

2. What should I do with the braided wire? It was soldered along with the red on my previous wiring.

Thanks again

[newey]

ET-

Leads on my PUs are red and white, how might I find which is hot and which is not? Is it as straight forward as "it's the white lead, because it's white and white is always hot"?

Not so straightforward as that. Different manufacturers use different wire colors, so there's no simple way to tell without a chart from the manufacturer.

But the good news is, it doesn't matter which is which so long as you wire both pickups consistently (IIRC, you are using a matched pair of pups from the same manufacturer, correct?).

The designation of one as "hot" or "not" is only important with respect to phasing, so if the pups are a pair, and you call both white wires "hot", the two should be in phase.

The braided shield is always soldered to your shield grounding point, usually to the back of a pot if you're not using the star grounding scheme.

[ethienistic]

gotcha

PUs are indeed matched Gretsch HiLotrons (that's why one gave a reading of resistance of 3.40 for the neck, the other 3.80 for the bridge)

For the braided shield, since I am using star grounding (chrisk dixit), it should be soldered with the "not" wire, correct?

[ChrisK]

For the braided shield, since I am using star grounding (chrisk dixit), it should be soldered with the "not" wire, correct?

NO.

Since you are using series and series out-of-phase on the neck pickup, the shield for the neck pickup cannot be connected to the same point as the "not" wire from the neck pickup.

Connect the shields to the star ground point. Connect the "hot" and "not" wires as shown in my diagram.

[ethienistic]

Ok. I'm going to have to ask I'm afraid: where on the diagram, pray tell, would the star ground point be?

I teach guitar to beginners, and at that very moment, I just know I have the same bovine look in my eyes as when I first explain the basic rules of harmony.

Thanks for your patience, chris.

[newey]

where on the diagram, pray tell, would the star ground point be?

Well, you can't find it because it isn't on the diagram. ChrisK's diagram shows you the signal path. Shields and grounds have been omitted since they do not vary (where you put them may vary, but their placement does not affect the wiring of the signal, I mean). ChrisK alluded to that several posts back.

Where you put the star ground physically, inside your guitar, is a matter of wiring convenience. Where it goes electrically is that it connects to the "ground" wire from your output jack beyond the last component in your signal path.

The star ground will collect, at one point, all of the following:

• The ground wire from your bridge/strings
  
• All the shields from your pickups
  
• A wire from your shielding (or, you can use a ring terminal for the star ground and screw it down to the shielding to make this connection)
  
• The output jack "not" wire. You can connect the star point directly to the output jack, together with the "not" connection from your signal. On Strats, it's often difficult to push that extra wire through to the jack cavity, so I usually connect the jack ground to the star ground point, and from there connect to the "not" of the signal.
  

The important thing is to keep your signal path separate from the shielding grounds until just at, or just before, the output jack.