What's the best single-control tone stack you've seen?

[tubeswell]

i may be wrong but isn't the princeton tone control essentially the same thing as a fender pro junior tone control? it is indeed effective up to a certain point but doesn't do much at high to maxed volume.

Well if you isolate the pro junior tone pot (and its two caps) and the vol pot, they appear in the same sequence in the circuit as the 5F2A, but that is where any similarity ends. The values of the pots and caps are different, and the topology of the amps in front of, and behind, the vol-tone set up are quite different. So they won't have the same effect at all (and I can vouch for the effectiveness of the 5F2A vol and tone controls).

[yunger]

Well if you isolate the pro junior tone pot (and its two caps) and the vol pot, they appear in the same sequence in the circuit as the 5F2A, but that is where any similarity ends. The values of the pots and caps are different, and the topology of the amps in front of, and behind, the vol-tone set up are quite different. So they won't have the same effect at all (and I can vouch for the effectiveness of the 5F2A vol and tone controls).

with the pro junior there is an interaction between the volume and the tone pots so you lose the high-pass aspect of the control with full volume. the reason i brought this up is that i would love to find a solution to the pro junior's tone control quirks. would changing values of the tone circuit overcome the interaction between volume and tone?

[WholeToneMusic]

No comparison

Comparing any part of the Princeton 5F2-A circuit with the Pro Jr is like comparing apples to oranges. They are completely different circuits from input to output. The 5F2-A is a single ended circuit which uses a 6v6. The Pro Jr uses a duet of EL84's. The tone stack uses different value components. The Princeton has a bypass cap on the cathode of the preamp which raises the gain of the amp and changes the bass response also. The Pro Jr does not use bypass caps on the preamp cathode resistors. The negative feedback loop is also different in the two circuits. Also the 5F2-A uses a 5Y3 rectifier tube and the Pro Jr uses diode rectification. All of these small nuances can contribute to the tone of the amp.

[tubeswell]

with the pro junior there is an interaction between the volume and the tone pots so you lose the high-pass aspect of the control with full volume. the reason i brought this up is that i would love to find a solution to the pro junior's tone control quirks. would changing values of the tone circuit overcome the interaction between volume and tone?

Changing the cap values will have a small effect on the frequencies passed, (as to how much why don't you try it and report back?), but it won't make the amp sound like a 5F2A because of what I said before - the two amps are completely different.

[pdf64]

Looking at the circuit, the pro juniors tone control range could be made much more effective at high volumes by moving the tone pot wiper to the other end of R5, the 470k volume pot feed resistor. The value of C3, 0.01uF seems rather high, especially if the above mod was done. 470pF would be more appropriate.
There's not much in the way of grid stoppers or low pass bandwidth limiting, so perhaps the above mod would let loose the dreaded parasetics.
BTW I agree that the 5f2A is the best 1 knob tone control. The interactivity is it's strength, at max vol the tonal control range is appropriate - what real use would a 20dB boost to the high end be at full volume, when the amp is already screaming? A simple, elegant and effective design. Peter.

[yunger]

when i mentioned the "tone control" i meant precisely that, relevant to the title of this thread....not the overall "tone" of the amps. Obviously the tweed and the pro jr are apples and oranges in the sounds they produce. however, all this talk about the princeton does have me intrigued to build one.
when my eyes look at the single knob tone controls of these amps, i see that when the volume pot is all the way up there is theoretically no more series resistance through that pot. this effectively cancels the high pass aspect of the tone knob. and by high pass i mean a simple rc filter that cuts lows. with my limited knowledge of electronics, i wouldn't have a clue how to boost the high end nor would i want to.

[WholeToneMusic]

Understandable Yunger, I may have gotten off on a tangent. Yes the tone stack is different on the Pro Jr. IMO the Princeton 5F2-A is one of the best sounding tone stacks. This is a good place to start.

[jbrew73]

[QUOTE=jrfrond;69578]That Gretsch circuit is actually pretty simple, even though it might look complex to some. The control pans between a low-pass (top section) and high-pass (bottom section) two-pole passive filter. It is accurately described as "darker in the lower settings, in the middle range it has a kind of blackface vibe, and gets brighter in the upper range", because the lower setting sends the signal through the low-pass filter, cutting the highs. The mid setting sends it through both low and high-pass, creating a midrange notch that could be described as the Blackface sound, and the higher setting rolls off lows and passes highs through the (you guessed it!) high-pass filter.[/QUOTE

How does to volume control setting affect this tone network? Seems that different volume settings would change the source impedance effect how the tone network behaves.

[Steve Conner]

what real use would a 20dB boost to the high end be at full volume, when the amp is already screaming? A simple, elegant and effective design. Peter.

I'll rephrase the question: what use would a 20dB cut to the low end be at full volume? Answer, quite a lot of use as it would prevent farting.

I've only played a Pro Jr. once, but I felt that the last quarter turn of the volume control turned it into a fart monster.

All of these simple tone control circuits have 1st order slopes. (Except maybe the Gretsch which I can't see right now.) This means that the range of frequencies affected is very broad, so there's not as much difference between a treble boost and a bass cut as you'd think.

[loudthud]

The link to the Gretch 6162 seems to be broken. Here's a new one: http://www.el34world.com/charts/Sche...retsch6162.pdf

[J M Fahey]

TYry the Dr Z single knob tone control, works very well.

[greekie]

I like pentodes. So I normally use a multi-poled switch to switch between different capacitors. My latest invention is a 2 row 12 position switch, that switches coupling caps between a stage on the first row, and capacitor bypass-caps on the second. That way I can fine tune different sounds with different guitars, and easily get to those sounds with a single tone control.

Please let me know if you (or anyone else) will be using this system, as I have some suggestions and tweaks... and like to get credit for many many hours of hard work! :-)

[woodyc]

In an otherwise flat amp, I like the controls that incorporate a notch filter.

There were lots of variations in old gibson amps. The Bell Stereo 30 (GA-78) sounds great - thats the one that was copied into the Matchless Chieftain and the later Dr Z Carmen Ghia. The mid control in a GA77RET is similar but the notch is deeper and the freq doesn't shift as much. The Skylark Tremolo has a more subtle version. You can optimize any of these to taste with resistor and cap values.

For a really whacked version of a notch based control, there is the Tone-X control in amps like the Vox Kensington -- but you need to change all the values unless you have a low impedance to drive it.

[Gaz]

I like the "Mid Bite" in the Tone King amps a lot. Kinda of thinking it's the Gretsch control now, but no way of knowing. I do know that's not a dual pot, however.

[Gaz]

Nah, not enough components. Any geniuses wanna take a stab at it?

http://www.proguitar.eu/ProGuitar.eu/Imperial.html#14