Exploring Tone Controls - intro and general discussion

[JohnH]

The idea for this thread is to explore the response of different types of passive tone controls for guitars. I thought it could start by covering the basic treble-cut design, and how different caps and pots react to various pickups. Then by instalments, test the more colourfully named or exotic concoctions such as Grease-Bucket, G&L (with bass and treble),TBX, Varitone, Torres ‘Mid-shaper’ and others that may emerge.

Results will be based on analysis and shown graphically, and the idea is to show what to expect from the different designs and component values, to help understand what is significant or not, and how to tweak a tone circuit to change response in a desired way. All this should help make choices easier for actual testing in the real world.

I plan to mostly drive this journey using GuitarFreak4, and it will be its first test drive after adding code to address these tonal variants. But there might be some Spice modelling too if needed.

Comments and ideas are encouraged, and in fact required. Let me know if you think this is a useful thing to do, so I can post the first part. Also, if there are particular circuit variants that should be added, I’m open to all suggestions. Also, real world sound samples or descriptions could be added. After a while, I’ll gather it all together for a post in the reference section of GN2.

OK? So I need to know if there are at least two people interested in this stuff....

cheers
John

[newey]

I think it's a good idea, John. Count me on board! We seem to have had a good deal of interest in tone controls lately, so some reference materials could be useful.

[Deleted]

+1 from me here.

[JohnH]

Thanks guys, a nod is much appreciated.

The tests will be based on the electrical properties of typical single coils of 2.4H and 5.5k, 'Vintage' PAF-style humbuckers with 3.8H and 7k and for some a 'Hot' humbucker of 6.4H and 13.5k.

Let's start by considering tone capacitors is a standard tone control, consisting of cap and pot in series. (See this now on the following thread:)

The effect of Tone Capacitors

[roadtonever]

First installment and it's already epic!

[sumgai]

John,

I've created a new sub-Forum just for you/this whole train of thought!

At this point, I think we'd be best served if you were to leave this thread intact as the starting point, but keep it focused on the nominally standard treble-cut control. Then start new threads for each variant, referring back to this thread as the jumping off point for discussion. I believe if you were to hold all the offshoot topics in one super-long thread (which might challenge 4real's sustainer topic for sheer length!), the end result will quickly get cumbersome for readers with specific needs/questions.

HTH, and thanks a heap!





sumgai

[ozboomer]

As always, an excellent topic for exploration/development, thanks John.

First-up... to include a link to the GuitarFreak4 spreadsheet/download, please. (Wish it would work in OpenOffice.. but I can use Excel at work so no biggy...)

A useful thing to include in light of this first (series of) posting(s), I think, would be to do a similar pair of graphs with the linear taper pot type; with the log taper (as shown), TheModel(tm) shows nothing much happens until you hit knob position 5... and as players having differing tastes, maybe a different response would be useful, hence the use of a linear taper.

...or maybe the thread is supposed to leave such things "...as en exercise for the reader" to explore with GuitarFreak4?

Naturally I'm going to be very interested to see how the G&L analysis works out


John

[JohnH]

Hi Oz, thanks for your comments.

You can download GuitarFreak4 from here, in the Reference section:

GuitarFreak4

It was written in Excel 2007, but there's nothing in it that pushes the boundaries of spreadsheet coding. I have tried down-saving it to 97-2003 and it seems to work fine. So you might find that OpenOffice does it anyway.

On Linear pots, the bit of tonal change that usually happens from 5 to 10 would be spread over all of 1 to 10, and everything else would happen below 1. I'll add that to the list. G+L wiring is indeed quite interesting, I've done the runs and will get to it soon.

[newey]

Great stuff, John! I think sg is right in calling for splitting the thread up as different schemes are explored, it will quickly become too cumbersome otherwise.

In looking at the graphs, I think ashcatlt may be right- just get a rotary switch and use the caps, forget the doggone pots. They aren't really doing very much over half the rotation anyway. . .

[JohnH]

Feb 18, 2014 19:35:23 GMT -5 newey said:

Great stuff, John! I think sg is right in calling for splitting the thread up as different schemes are explored, it will quickly become too cumbersome otherwise.

In looking at the graphs, I think ashcatlt may be right- just get a rotary switch and use the caps, forget the doggone pots. They aren't really doing very much over half the rotation anyway. . .

Alright, we'll try it like this but I was initially concerned by Sumgai's thread-shifting. I do want to generate discussion and comment and ideas, and do not want to discourage this by having too buttoned-down a structure. Some rambling is OK, and I was going to condense it later.

I think this particular thread might become the main general place to discuss.

On pots v caps, I have some runs coming showing different cap-only results. One thing that the resistors do is to damp down the peaks of response. With caps only, there is always a peak and you get to choose where it is, but not how high it is. So those who just want to take a bit of the ice-pick edge off may be best served with a pot, which is what happens in normal tone controls in the 6 to 10 region.

[0wnyourtone]

Thank you for this thread. I think the latter statement is significant to the average player who may be contemplating better owning his or her tone.

I think tone-switches (caps with no pots) are incredibly underrated, as they essentially give the user an "alternate pickup" in that the resonant peak is high like a pickup, yet at it can change the frequency of the peak.

On the other hand, if you are wanting to reduce harshness, as John stated, the standard tone is your best bet.

I like doing both.

[sumgai]

John,

I've reconsidered the move to being below "Reference Articles", and re-positioned this sub-Forum to the Guitar Wiring Forum. Like you, I hope this engenders even more discussion.

However, if you wish to "cull" the good parts and post them to a separate Reference Article, don't let me (or newey) hold you back!







sumgai

[col]

Feb 18, 2014 18:22:55 GMT -5 JohnH said:

It was written in Excel 2007, but there's nothing in it that pushes the boundaries of spreadsheet coding. I have tried down-saving it to 97-2003 and it seems to work fine. So you might find that OpenOffice does it anyway.

John,

Might you post an Excel 2003 version? Compatibility conversion results in a read-only spreadsheet. It is about time I upgraded!

Col.

[JohnH]

Feb 21, 2014 16:28:16 GMT -5 col said:

Feb 18, 2014 18:22:55 GMT -5 JohnH said:

It was written in Excel 2007, but there's nothing in it that pushes the boundaries of spreadsheet coding. I have tried down-saving it to 97-2003 and it seems to work fine. So you might find that OpenOffice does it anyway.

John,

Might you post an Excel 2003 version? Compatibility conversion results in a read-only spreadsheet. It is about time I upgraded!

Col.

OK I will. I post here when its done. Gotta go feed horses now...

[col]

Thanks, John. Much appreciated.

[JohnH]

Feb 21, 2014 16:35:28 GMT -5 JohnH said:

Feb 21, 2014 16:28:16 GMT -5 col said:

John,

Might you post an Excel 2003 version? Compatibility conversion results in a read-only spreadsheet. It is about time I upgraded!

Col.

OK I will. I post here when its done. Gotta go feed horses now...

Current Version GuitarFreak 4.03

25/2/14 - just editing this to point back to the GuitarFreak thread, that way there is only one place to update with new versions:

The current version is here, with 2007 and 97-2003 versions:

GuitarFreak

[popsaka]

Feb 18, 2014 6:33:13 GMT -5 JohnH said:

Thanks guys, a nod is much appreciated.

The tests will be based on the electrical properties of typical single coils of 2.4H and 5.5k, 'Vintage' PAF-style humbuckers with 3.8H and 7k and for some a 'Hot' humbucker of 6.4H and 13.5k.

Let's start by considering tone capacitors is a standard tone control, consisting of cap and pot in series. (See this now on the following thread:)

The effect of Tone Capacitors

Please include P90 type single coil pups... (thanx in advance)

[JohnH]

Feb 24, 2014 12:59:09 GMT -5 popsaka said:

Feb 18, 2014 6:33:13 GMT -5 JohnH said:

Thanks guys, a nod is much appreciated.

The tests will be based on the electrical properties of typical single coils of 2.4H and 5.5k, 'Vintage' PAF-style humbuckers with 3.8H and 7k and for some a 'Hot' humbucker of 6.4H and 13.5k.

Let's start by considering tone capacitors is a standard tone control, consisting of cap and pot in series. (See this now on the following thread:)

The effect of Tone Capacitors

Please include P90 type single coil pups... (thanx in advance)

OK, its a good idea
J

[Ro_S]

JohnH - 

Do you have any topic threads dedicated to any of the following types of passive tone controls:

- vari-tone type things (including without an inductor choke).

- "strangle switch" type control of the Fender Jaguar. (a fixed cap bass cut?)

- the 2-way tone switches used on some other vintage guitar models, such as by Hagstrom, Hofner, Supro, Gretsch.  (I don't know what such controls are, but I can suggest specific guitar models)

thanks

[JohnH]

There's a few things written about Varitone circuits, use search to find them. I don't know about the other two types.

If you want to explore these designs, GuitarFreak (see reference section) can deal with most of them including inductor / varitone and PTB circuits.

[Yogi B]

Nov 4, 2018 14:45:00 GMT -5 Ro_S said:

"strangle switch" type control of the Fender Jaguar. (a fixed cap bass cut?)

Yep, traditionally a 3nF cap, it's placed before the tone control (probably to save on wires running back and forth, to the (lead) tone control then back to strangle switch). This has the consequence that despite the cap value being fixed, the resulting cut off frequency is dependent on the tone control also, making the tone control more noticeably cut more bass than treble during the first half of it's rotation.

the 2-way tone switches used on some other vintage guitar models, such as by Hagstrom, Hofner, Supro, Gretsch.

I was recently reminded to look into how exactly a Gretsch was wired after watching a Stray Cats show (though the likelihood of picking one of Setzer's Gretsches that hasn't had its tone switch removed isn't great). Anyway, looking at this diagram from Gretsch themselves, the tone switch is actually a 3-way, choosing between: nothing, a 3.9nF capacitor, or a 12nF capacitor.


I don't know about the other's, but I believe that Hagstrom Swedes' also have a 3-way tone switch, though the Condor/Impala does only have a 2-way.

[newey]

I believe that Hagstrom Swedes' also have a 3-way tone switch, though the Condor/Impala does only have a 2-way.

I think that's right. There are a number of Hagstrom websites that may have some specifics. But they were big on the fixed-cap tone attenuators.

In the late '60's- early 70's, in my 8th-grade garage band (yes, we were as bad as that sounds), our lead guitarist had a Hagstrom I, which had slide switches instead of a tone control, with a master volume. I believe these were on-on switches. The Hagestrom I was fairly unique in that it was a clamshell design, with the back half of the body of wood, covered in red Tolex, while the top was a fiberglass molding that bolted to the back half.

IOW, back in the day, when guitars weren't all cookie-cutter clones of popular designs . . .

[Ro_S]

Nov 5, 2018 22:51:41 GMT -5 Yogi B said:

I don't know about the other's, but I believe that Hagstrom Swedes' also have a 3-way tone switch, though the Condor/Impala does only have a 2-way.

Yeah, I was thinking of the Condor/Impala myself.  I'd like to know exactly what its 2-way tone switches do and what they are. 

[blademaster2]

I own a Condor from 1967. The switches for tone are, in my view, quite limiting. Here they are:

- The 'low' switch connects a 10nF capacitor from the signals of the pickups (which are connected by their own individual switches) directly to ground. I find it a bit too muffled and has no adjustment to alter it once selected.
- The 'middle' switch adds no capacitance to the pickup signals and passed them straight through. This is by far my favourite setting.
- The 'high' setting adds a series capacitor of 3nF to the pickup signals, cutting the low frequencies. This sounds okay but it thins the tone and I prefer the richer tone of the pups on their own.

In addition to this, the electronics has an 'accompaniment' switch that introduces a 50k potentiometer, shunting to ground, onto the pickup signals to add a second volume adjustment in parallel with the 250k potentiometer main volume control. I seldom use this, as it slightly reduces the highs while reducing the volume.

Overall, I prefer the pickups straight out. The neck pickup is my favourite (similar to a Strat). I found that you can switch more than one pickup on at a time and it thins the tone like a Strat does, but I am not sure if it is stressing the plastic interlocks on the switches or not so I do not do that often.

In summary, the Condor electronics is limiting but I do like the guitar and its playability.

[Ro_S]

blademaster2 -

Many thanks!

So is the 'high' control setting identical to the 'strangle' switch on a Fender Jaguar?

The 'middle' control setting is just normal/unaffected? or have I misunderstood?

[blademaster2]

I need to know first what the Jaguar uses to make a comparison (I have not looked yet), but you are correct that the 'middle' control switch on a Condor just connects the selected pup straight out through the volume control and there is no capacitor in the circuit at all.

[Ro_S]

Nov 8, 2018 9:53:16 GMT -5 blademaster2 said:

I need to know first what the Jaguar uses to make a comparison (I have not looked yet), but you are correct that the 'middle' control switch on a Condor just connects the selected pup straight out through the volume control and there is no capacitor in the circuit at all.

YogiB wrote above that the Jaguar 'strangle switch' uses a 3nF cap.     Here is a weblink to a circuit diagram I've found:  here

[Ro_S]

Re: Gretsch tone switch -

I've found the following linked diagram for a Country Gent model.    I can't vouch for its accuracy.   link

[frets]

Hey y’all,
A “Wish” - In order for John’s research to be comprehensive, it would be great if novel tonifiers that we have created on our own could somehow be tested in accordance with the standardized assessment methodology John will employ. I have a couple of unique tone pot mods that would be great if tested along side others. I know the response from the group will be to test these alone myself utilizing Guitarfreak; however, it would miss John’s interpretation that would be far above any of our paygrades. I just wish myself, that I could send built novel tone controls to be appraised within an expert environment scenario. Just a wish. Perhaps a methodology that can be replicated as far as the testing approach will emerge. For to go forward includes discovery of tone configurations that are unknown but to the inventor.

[JohnH]

Hi frets, thanks for those comments. I'd be happy to put an idea or two of yours into either GuitarFreak, or if it's outside of what that can do, a Spice model. Which of your diagrams are you most interested in exploring? If it's an idea tbat you've built, then also let me know approximately what sort of pickups it goes with, and the pot values.