Modern and 50's Wiring

[JohnH]

(Stickied..... instantly! Too good to let this drop down at all. Thanks, John!)



OK, modern wiring and 50’s wiring:

This choice comes up frequently on forums wherever Les Pauls are discussed. It relates to whether the tone controls are wired before or after the volume controls.

Here is a schematic, using 5Spice, representing one pickup on a modern LP, with a PAF humbucker pickup:



It uses 500k pots, and I have represented a short guitar cord of about 10’, without adding a treble bleed cap to the volume control, since that would be a non-standard addition (a good addition IMO, but that is a different story)

Here it is, wired 50.s style:



At full volume, both are identical in response. This shows the frequency response as the tone pot is reduced in 10 linear steps:



Note the last step, from 50k down to 0k, would represent 0-1 on a linear pot but 0-5 on a log pot, which shows why a log pot is better for smoothing out the response. You can also see the initial resonant peak, when at full volume and tone at 10.

The differences between modern and 50’s wiring start to occur when volume is reduced. The following have the volume pot set at 50%, which is 5 on a linear pot and about 7 on a log pot, resulting is a general 6db volume reduction:

Modern wiring, with 50% volume, tone pot 0-10:



50’s wiring, with 50% volume, tone pot 0-10:



Now you can see the difference. At full tone, and 50% volume, the 50’s wiring is in fact slightly brighter, which is due to it loading the pickups less. However, this does not compensate for the loss of the initial resonant peak. This extra brightness at reduced volume with full tone is the main reason some advocate 50’s wiring.

But as the tone is reduced, while the modern wiring acts fairly consistently on the treble, the 50’s wiring starts to cut deeply across all the frequencies except the very lowest, acting more like a volume control. The reason is that with modern wiring, the tone control acts consistently on the pickups, while with 50’s wiring, it is acting through the resistance of the volume control, resulting in it seeing a variable impedance, cutting much more deeply when the volume pot is reduced.

(Ill leave that last paragraph for a while, but if I think of a better way of saying it I’ll edit it later!)

This inconsistent tone response is why I would prefer modern wiring.

Cheers

John

[sumgai]

John,

First, thanks! This answers the recent questions of several newer members. I trust that they will see this thread, and ask questions here, as appropriate.

A bit more of a deep explanation (emphasis added):

But as the tone is reduced, while the modern wiring acts fairly consistently on the treble, the 50’s wiring starts to cut deeply across all the frequencies except the very lowest, acting more like a volume control. The reason is that with modern wiring, the tone control acts consistently on the pickups, while with 50’s wiring, it is acting through the resistance of the volume control, resulting in it seeing a variable impedance, cutting much more deeply when the volume pot is reduced.

Actually, if the impedance were to be increased (which it isn't, in your example (Solving the RLC equation will show that.)), the low frequencies would tend to be allowed to pass, and not hindered. Let's look more closely at the 50's diagram, and see if we can't figure out why the tone control cut much more deeply than anticipated.

Note that the upper leg of the volume pot also forms an RC circuit with the 130pf cap (the internal pup capacitance). Since that RC time constant changes with the rotation of the volume pot, you now have not one, but two tone circuits in play! Since one is in series with the other, the result will be the downward movement of the -3dB point, something that ordinarily does not occur in simple tone controls. In short, you now have a state-variable low-pass filter. It certainly is 2nd order, until that last step - that's a doozie!

For the ChrisK-inclined aboord here, this kind of complex analysis is ratiocentric, but it yields more readily to vector analysis. Or maybe that's just the way my mind works, I dunno. (When it is working. These days, it's hard to tell what it's doing! )

HTH



sumgai

[jcgss77]

Ok-newb question here-so, what if we somehow put a pot in the PUP, and omitted the tone control, would that pup be a more effective tone control, somehow with a resistor in parallel for a possible brightness evening function? Is there any existing theory on this? Or would it just kill the PUP in question, or am I just lost in a fantasy world of perfect tone pots?

[thinman]

This is a fantastic post. I've scoured the net for info like this - thnxalot.

It looks like the analysis is done by computer ? (rather than measured on a test circuit ?) Although I'm not sure (Maybe I've not read it thoroughly enough yet ?)

I would love to see the analysis of the circuits favoured by Kay (maybe Harmony ?) 50s guitars where the "signal hot" output from the pickup is taken to the Volume Pot wiper.



The main difference is then that, as volume is wound down, the "load" on the pickup is decreased and the resonant peak gradually disappears (as I see in your graphs). However, this means that tone changes with volume which can be desirable ? (or undesirable ?).

Also - the Dano schemes where 2 single coils are in series (this gives a GREAT sound)

I was thinking of wiring that scheme with a single vol pot on the output and variable pots in parallel to each pickup so that they may be gradually shorted out. This may (or may not ?) give a range of useful tone variations withouth the need for capacitors ?

Great post anyway - thanks

Robby

[JohnH]

Hi thinman, welcome to GN2 and thankyou for your comments.

That is indeed a computer analysis, using one of a number of programs built around the 'Spice' modelling system. these days, my favourite is 5spice, its a free download and its very easy to build the circuits schematically, then run them.

Such analyses capture the electrical characteristics of a guitar circuit, and an electronic filter, though they don't know about the specific tones of different pickups, their actual output or position on the guitar. Never-the-less, they can be very useful in adding insight into what affects what electrically.

I'll also give this spreadsheet another plug:, which has been updated recently, and will do the modern/50s wiring comparison, and you can put in properties to model series wiring:

GuitarFreak 4

(General friendly hint to others: ..still looking for anyone willing to comment on this version)

However it doesn't currently do the 'reversed' wiring that you drew here. The reason I didn't include that is that it is generally not a very good idea!(IMO) ..significant tone loss as your roll down. But, if you go a couple of posts down on the GuitarFreak thread, there is a link to another spreadsheet called 'Voltone', which will do it. Try it for yourself and see what you think.

cheers

John

 

[0wnyourtone]

Thanks for the info John. Now I KNOW why I don't like fifties wiring! ;-)

The thing that mainly bugged me about it was the inconsistency in tone as I changed the volume. If I go to the work of dialing in a specifics sound, I'd like that sound to still be there when I turn the volume down a tad!

It's nice to see the 'why.'

[newey]

Over at The Gear Page.net, one of the members has done some empirical testing which comes down on the side of the modern wiring, just as JohnH suggests:

www.thegearpage.net/board/showthread.php?t=224610

Her's what he did, quoted in full:

"50's" les paul wiring debunked?
the received wisdom on this and other gear-type forums is that gibsons wired so-called "50's" style, with the tone pot wired to the volume through the volume pot's middle lug, will clean up better when the volume is rolled down than guitars wired "modern" style, with the tone wired in through the "input" lug, the one opposite the grounded lug, supposedly due to less loading from the tone pot. this has not been my experience, so in the tradition of esteemed poster John Phillips, i wired up a "debunker" switch to test what really happens.

i put the output of the 500k tone pot to the middle lug of a two-way mini toggle, and the two output poles of the mini-toggle went to the input (far) lug and the output (middle) lug of the 500k volume pot. this way, i could instantly switch between "50's" and "modern" setups.

i then turned the tone pot about halfway down to make it's effect obvious, and tested as follows:

with the volume all the way up, i could tell no difference, which was to be expected, since the two live lugs of the vol pot are shorted together at this point.

with the volume turned about halfway down, the difference between the two options was clear and dramatic: one way was far brighter than the other. and the kicker? once i traced the wires back to the connections, it turns out the modern wiring option was the clearer setting!

the lower the volume was turned, the more obvious the difference, as the 50's setting got dull much sooner than the modern setting. turning the tone knob all the way down also exaggerated the effect, again darkening the 50's setting much more than the modern setting.

the hard test was to hear a difference between the two settings with the tone all the way up. i thought that the modern setting was still a tiny bit brighter, but i couldn't positively rule out placebo effect at that point.

my theory is that with the tone circuit tied to the input lug modern style, when the volume is turned down, the guitar output is panned away from the pickup and from the tone pot, lessening it's effect. with the 50's circuit, however, as you pan away from the pickup with the volume pot, the tone pot is still fully connected to the output.

i tried this test with two different guitars, with the same results both times. (i didn't test the different tone pot configurations, but supposedly they don't matter since they just use two lugs of the tone pot as a variable resistor, rather than the three-lug divider network of the volume pot. maybe i'll do another test of this aspect later.)
__________________
Walter Wright
Guitar Repair Gnome
Alpha Music, Va Beach

So, apparently theory and actual testing both point to the same conclusion.

[numpty]

Whilst researching this subject I have discovered something which has been called "The Falbo Mod" on another web page. It is basically a variation of modern wiring with a twist involving the placement of the treble bleed. Instead of placing the "bleed" on the input of the volume pot, it is placed on the unused lug of the tone pot and this leads to the output of the volume pot. The theory is that the "bleed" is gradually faded in or out of the system instead of being fully on at all volume levels, this fading is proportional depending on the position of the tone knob. I will attempt to give a link. I am not sure if I have done this correctly so forgive me if it doesn't show. ashbass.com/AshBassGuitar/index.html. I am new to this and ask your indulgence if this has been discussed but I am unsure how to search the forums.

[newey]

numpty-

Hello and Welcome to G-Nutz2!

Your link just leads to the homepage for AshBass, not to the diagram you are referring to.

To post a weblink into a forum post, navigate to the page you want to link to and copy the URL to your clipboard. Then paste the URL into your post. Highlight the URL to select it, then click on the first colored button on the right of your typing screen, it looks like a world globe with a sheet of paper next to it.

Using the colored button simply adds "url" tagging to each end of the URL string, enclosed in square brackets. These can also be typed into place, for those who don't use a mouse for such things.

[numpty]

Hi Newey, Thank you for the welcome and your posting advice. I am struggling, being new to this, to get to grips with this url malarkey but will re-attempt.link I don't know if this has worked. I am interested in the opinions of the guys on here about this mod as it seems to be a really good solution to get a usable treble bleed without certain higher frequencies being either lost or being ever-present. I like the idea that a. it utilises the unused lug on a tone pot and b. it utilises the tone pots own sweep to vary the treble bleed. This is an idea I am sure some of you must have come across in this forum but I was unable to find any reference to on here and forgive me if it has been discussed before without my knowledge. If you have previous discussion on this topic could you please link me to it, thank you. Just in case my linking attempt doesn't work, I am including this written one as follows, www.mylespaul.com/forums/showthread.php?t=82799. Fingers crossed.

[JohnH]

Hi Mr Numpty

Ive seen that design though not tried it myself. It does seem to be well liked by those that do so. My issue would be if you need to turn tbe tone down at lower volume but then have to turn it back up at full volume - double handling of knobs!

But worth a try and we will be interested to hear about it if you do.

I did some analysis on a few versions of treble bleed in this thread:

guitarnuts2.proboards.com/thread/5317/treble-bleed-circuit

Ever since then, Ive used the same on all my guitars, which is a fixed 150k resistor and 1nF cap in parallel across the volume pot hot and center lugs. Thats for a 500k volume pot. With a 250k, a 120k rezistor is a bit better.

The tapered bleed is also discussed on that thread, a few posts down.

[numpty]

Thanks for your link JohnH, I must have read that thread at sometime and completely missed that. Can I just say now that I love to read these pages and consider this site to be amongst the best places on the internet. I am a novice at this stuff and often just peruse blindly to learn about a subject I am only recently beginning to learn about. I couldn't be in better company in this regard, I greatly admire the folks on these pages for their freely given knowledge and seemingly endless patience and good humour. You guys are awesome. Many thanks all.

[sumgai]

newey,

In numpty's defense: On the ashbass site, the URL stays the same no matter what page you're visiting. Obviously it uses some scripting to select a "page" to view, and the results of that choice don't show up in the Address bar... sad to have to say.

---

numpty,

Hi, and welcome to The NutzHouse!

The so-called Falbo Mod is best described as a semi-variable treble bleed circuit.  An analysis follows:

In effect, using the 'unused' portion of the tone control is akin to our very own ChrisK's "The FREE Neck On Switch"* - no visible changes to the guitar itself, but more tonal variation is possible.  Obviously there are big differences, but using the unused portion of the tone control is attractive, to say the least.  (Besides, it makes the Beta Particle Bombarder smile quite happily! )

My first reaction is that since the cap value does not change, then the frequency response doesn't change either - only the amount of treble that pass through can change, but that's enough for most players.  By this, I mean that the volume level of the audible higher frequencies will be changed by rotating the tone pot, but the point on the frequency spectrum where the effect takes place, that will remain the same, no matter what.

Now, the foregoing is actually not quite true.  Since you have tied the VTB (variable treble bleed) to the master tone capacitor through the tone pot, they are now both in the circuit, effectively at all times.  The pot's resistance is the only thing selecting between one, the other or both, there being no switches involved. That says to me that you are (or more correctly, your guitar is) in a constant state of balancing between the two caps.  My only caution to you at this point is that you will experience one or more peaks and valleys in your response curve, not just a simple roll off at one frequency point.

In addition, all of this does play a small but important part on the loading of your pickup.  While there isn't any additional resistance in the circuit, that extra capacitor in series with the variable resistance element will affect the output impedance of the pickup itself.... as do all cap-and-resistor combinations used for treble bleed purposes.  In turn, this does affect how the pickup sounds... just ask JohnH for a SPICE workup to see what I mean.  However, it should be obvious that a static combination has a constant effect, one that is predictable at all volume levels and tone-control levels, whereas a variable impedance will be hit-and-miss at best, and will be repeatable (finding again a particular sweet-spot) only with learned muscle memory - markings on a knob won't be precise, only a good guide.

All of this isn't to say that your idea is not a good one, just that there are always "gotcha's" lurking just behind the pickguard, waiting to step out and do a good imitation of Mr. Murphy, if you know what I mean.

Hmmm..... in further cogitation, I wonder just how close all this is to ChrisK's "FREE Woman Tone".

HTH

sumgai

* That thread has been controverted by asmith, here:

ChrisK's FREE Neck On Switch

[reTrEaD]

Aug 31, 2016 3:19:23 GMT -5 JohnH said:

Hi Mr Numpty

Ive seen that design though not tried it myself. It does seem to be well liked by those that do so. My issue would be if you need to turn the tone down at lower volume but then have to turn it back up at full volume - double handling of knobs!

But worth a try and we will be interested to hear about it if you do.

Yes John, the necessity of fiddling with the tone knob after every volume change makes this very undesirable, in my humble opinion.

1 - The tone-cut part of the circuit is 'modern wiring' which is good.
2 - The treble-bleed portion is variable between cap-only (which overcompensates at low volume settings) and cap-with-series-resistor (which adversely affects the shape of the curve.

I reckon for any tone setting at full volume, you could adjust the tone knob to get an *acceptably* close tonal setting at a lower volume by adjusting the tone knob. But there will be no setting of the tone knob where the volume control acts without affecting the tone so much that a tone knob adjustment is necessary.

In my opinion, the cap-with-parallel-resistor has the best combination of simplicity of operation and performance without any special parts like a ganged pot for the volume control. And I think 'modern wiring' for the tone control is best.

But as always ... YMMV.

[grooveiron]

Aug 31, 2016 3:19:23 GMT -5 JohnH said:

Hi Mr Numpty

But there will be no setting of the tone knob where the volume control acts without affecting the tone so much that a tone knob adjustment is necessary.

I use this scheme in most of my instruments. All my pots are 500k audio.I find that with the tone set at 7 or 8, volume adjustments are tonally very consistent - as if a nice "treble bleed" were present. With tone above 7 or 8 reducing volume acts as a bass cut, and when tone is below 7, treble is cut in the normal manner. I find this incredibly efficient.

[goku]

Hi John,

Thank you for sharing your wisdom with us.!!! I am new here and found many of your posts!  Well done!

[pablogilberto]

Feb 11, 2008 15:51:13 GMT -5 JohnH said:

It uses 500k pots, and I have represented a short guitar cord of about 10’, without adding a treble bleed cap to the volume control, since that would be a non-standard addition (a good addition IMO, but that is a different story)

Hi JohnH

How do you successfully add a Treble Bleed Circuit (cap and resistor in parallel) for the Modern Style Guitar Wiring?

At Neck or Bridge Position, I can see that it will work fine.
For the Middle position (Neck and Bridge in parallel), will there be any problem when it comes to the response?

For dependent volume wiring (pickup connected at the left/upper lug of vol pot), it looks good.
For independent volume wiring (pickup connected at the middle lug of vol pot), I think there will be an issue when one volume knob is set to zero. There will be a tone suck because there will be a path to ground via the Treb Bleed (capacitor).

Have you observed this?
What's your suggestion?

Thanks!



EDIT by sumgai:  Pablo, please consider reading our new "Instructable" on quoting postings, at Please help us prevent quote-cluttered threads! Thanks.

[JohnH]

hi Pablo

With basic Modern LP wiring, such as I have on my Gibson, I use a treble bleed of 150k in parallel with 1nF, on both volume pots, with 500k audio taper pots. It works fine in all settings and combinations, even with series wirings.

Independent wiring is such a generally terrible idea, which wrecks tone as you turn down, that any further problems that it might create are not worth fixing!. But that's just my opinion.

50's wiring, although I don't like it myself, has to be recognised as being well liked by quite a number of discerning players, who are very adamant about it, and I respect their views.

[cooltone]

Hope all is well Gentlemen,

Just play devil's advocate...wrt LP humbuckers and 50s wiring.

For many years I have been searching for a solution to loss of treble as I reduce my guitar volume. I have tried many passive solutions without joy, the tone wasn't right. Reluctantly I moved to active solutions and had interesting results with 50s wiring.

The reason for going active was to get better control of the Q-factor

I used this for my reasoning: Q = R*(C/L)^1/2 - for me it's a useful approximation

where
R = HB load resistance
C = HB load capacitance
L = HB inductance

Just to re-iterate the problem, when the volume is turned down the cable capacitance is removed from the load capacitance, so Q is reduced and the cable capacitance forms an LP filter with the top arm of the volume resistance reducing Q further.

Initially, I used a fet to buffer and Modern Wiring to isolate the cable capacitance from the volume control. To eliminate stray-capacitance from the output of the guitar volume, I drove the shielding for the switch-wiring with the buffer (same concept as wha-wha designs). Then I added back a capacitor directly across the HB to emulate the cable capacitance ~ 800pF

The design worked and had a consistent treble peak across the full range of volume, but it didn't sound great in my set up - I have my amp (5W) near full volume for distortion and turn the guitar volume down to clean it up. Now it sounded great a low volume, but to harsh at full volume.

This is when I switched to 50s wiring. I put the tone pot on the output of the guitar volume and removed the cap emulating the cable. It now works fantastic. At full volume there isnt much treble lift because the load capacitance is small - which is great for distortion. At lower guitar volume the treble lifts because the load impedance across the HB increases (~ 1.6dB lift according to LT Spice). At all guitar volumes the guitar tone behaves in a sensible way - while it does shelve much in the way you describe above, on my amp it sounds great.


HB: Vanson Alinco 2
Vol: 250k Audio
Tone: 47nF/250k Audio
Buffer: J113 source follower - 15k Output Impedance (wish I'd seen yours earlier! This one is slightly different, but there seems to be a number of designs on here, I'll post if there's interest)

Anyway I thought this might be of interest to those using simple guitar/amp set ups.

Cheers

[JohnH]

hi cooltone
That's an interesting variant for these issues to put 50's wiring with a buffer. I could see how that'd give you a very clear tone at lower volume, which could be great for strumming and finger-picking etc!