James tone stack followed by Framus mid?

[edvard]

A few weeks ago, I went searching for the schematic of a solid-state amp that, for the life of me, I can't remember now.  It was late at night and I remember thinking "I'll look for the same thing later" and went to bed.  3 days later I am still trying to remember, and I can't find it in my browser history.  In the fog of faulty memory, I recall it was a fairly modern analog circuit, like a Quilter or Hotone or maybe even Joyo. 

What I DO remember was that the tone control was passive, and was a James (can't remember if it was the one-cap variety or two) bass & treble followed by a Framus mid.  There may have been an op-amp in between, but I'm not sure.  Does anybody know what it might have been? 

Yes, I COULD simply look up those circuits and wire it up myself and see how it sounds in my preamp experiments, but I always like to see how others do it as a baseline to tweak.

[Elijah-Baley]

Framus Mid is a passive filter, it just cut mid and don't boost it, if I remember well.
Is this what do you want?

[edvard]

Yep, I'm aware the Framus mid is a passive mid-cut.  I was looking for a schematic of its use in a modern analog solid-state amp that had it in conjunction with a passive Baxandall/James Bass/Treble tone control to make a Bass/Mid/Treble tone stack. 

I like the predictability of the James and Baxandall, but it sounds rather sterile, and the mid controls usually shoehorned in don't work all that well.  The Framus mid control has a pretty wicked notch at the cut end (which I predict would sound more Fender/Marshall/Vox-ish), but completely flat at the top end, which I predict would add more midrange than your typical F/M/V tone stack. 

I may be wrong, but I'm encouraged by the fact that a modern commercial amp has used such a configuration, I just wish I could remember which one it was.  I'll probably end up simply taking a generic James and the stock Framus and see where I can go from there.

[teemuk]

Post late 1980's Fender SS amps (e.g. Frontman) have something similar. It isn't a super rare setup and I'm not going to start listing dozens of amps with Baxandall/James and some iteration of a variable notch-T filter. Why do you even need a schematic?

The drawback of the "T-notch" is that the scoop frequency slides along the dial setting just like in the generic "FMV" tone control. It's not very "consistent" in its tone.

For mid-range control, if it's going to be a separate circuit anyway, I'd look at that "Baxandall" circuit which combines bass and treble circuits to create a mid-band control. This is far more consistent to dial and can also boost (e.g. SansAmp, Gallien-Krueger).

The usual "three-band Baxandall" is at the borderline of control onteraction but if you split the mid-range to separate circuit section you can eliminate interaction. You can even chain as many mid-range controls as you need, at different cutoff frequencies naturally. Usual GK setup has "hi-mids" and "lo-mids" controls.

Another alternative I'd think about would be a generic parametric mid-range control (e.g. Peavey, Pearce).

[Vivek]

Dear Teemu

Isn't baxandall mid too low Q ?

[Vivek]

Framus on TSC in the web

https://www.guitarscience.net/tsc/framus.htm#RIN=1k&R1=100k&RM=1M&RL=1M&C1=1n&C2=1n&RM_pot=Linear

[edvard]

Post late 1980's Fender SS amps (e.g. Frontman) have something similar. It isn't a super rare setup and I'm not going to start listing dozens of amps with Baxandall/James and some iteration of a variable notch-T filter.

The schematic I searched for was a recent design, as in the last ~10 years or some point since.  It still nags me that I can't remember which one it was.

Why do you even need a schematic?

Because I could simply copy the Bax/James and Framus circuits from TSC and start from there, but as I said ^^ I wanted to see how a professional designer has done it before venturing out on my own tone journey. 

The drawback of the "T-notch" is that the scoop frequency slides along the dial setting just like in the generic "FMV" tone control. It's not very "consistent" in its tone.

Agreed, but folks keep using the FMV stack for new designs with tweaks here and there, so a bit of frequency slide doesn't seem to be much of a hindrance.

For mid-range control, if it's going to be a separate circuit anyway, I'd look at that "Baxandall" circuit which combines bass and treble circuits to create a mid-band control. This is far more consistent to dial and can also boost (e.g. SansAmp, Gallien-Krueger).

Yep, I've tried that one, and never got any useful range out of it.  It's like turning it up gives a "suggestion" of midrange, but not enough to make you go "Hey! That's some midrange!"

The usual "three-band Baxandall" is at the borderline of control onteraction but if you split the mid-range to separate circuit section you can eliminate interaction. You can even chain as many mid-range controls as you need, at different cutoff frequencies naturally. Usual GK setup has "hi-mids" and "lo-mids" controls.

Another alternative I'd think about would be a generic parametric mid-range control (e.g. Peavey, Pearce).

The circuit I found I think had an op-amp isolation stage between the Bass/Treble and Mid controls, so that's sound advice.  Great gadzooks, I wish I could remember what it was...
I never did like the Hi-Mid/Lo-Mid style controls, though I do admit, they offer more flexibility to the tone.  If I were to do that, I'd just go all active with shelving controls for bass and treble, and tuned gyrators for the Lo and Hi Mids.  Hell, at that point I might as well chuck it all and lift the Metal Zone tone control. 

No, I want to stay with passive controls because they're simpler and the frequency anomalies sometimes make the tone more "interesting". 

[ElectricDruid]

No, I want to stay with passive controls because they're simpler

I dispute this. Often people put a passive tone control in, and then they get a big loss of volume, so then they stick a active booster stage on the end to provide some recovery gain and keep things at unity. You might as well put the gain in the tone stack and make it an active stage and avoid the problem in the first place. I honestly wouldn't use a passive tone control unless I was trying to avoid adding an op-amp because I hate odd numbers of op-amps.

[Fancy Lime]

No, I want to stay with passive controls because they're simpler

I dispute this. Often people put a passive tone control in, and then they get a big loss of volume, so then they stick a active booster stage on the end to provide some recovery gain and keep things at unity. You might as well put the gain in the tone stack and make it an active stage and avoid the problem in the first place. I honestly wouldn't use a passive tone control unless I was trying to avoid adding an op-amp because I hate odd numbers of op-amps.

+1 to that. Active Bax is usually less parts, more convenient part values, and better behaved than passive James plus make-up gain stage.

[Rob Strand]

I dispute this. Often people put a passive tone control in, and then they get a big loss of volume, so then they stick a active booster stage on the end to provide some recovery gain and keep things at unity. You might as well put the gain in the tone stack and make it an active stage and avoid the problem in the first place. I honestly wouldn't use a passive tone control unless I was trying to avoid adding an op-amp because I hate odd numbers of op-amps.

The assumption about flatness at the central position is also false.   At mid position log pots are all over the place.   The whole design of the James tone control is the amount of boost and the part values are all tied to the assumption that log pots tap at 10% when centered.  I regularly see 15% and sometimes 20%.   The old National Semiconductor "Audio Handbook" ("Audio/Radio Handbook") presents a James design procedure which adds resistors to the pots in order to reduce the effect of pot taper tolerances.

[edvard]

RE: flatness of EQ or lack thereof, component value tolerances, active vs. passive:

I. Don't. Care.

I got a hair in my butt about experimenting with a circuit I saw used in a schematic I found whilst staying up too late and wondered if anybody could confirm what my memory and browser history could not.  Nobody did, so that should be the end of it.  Done, finito, halten, cesser.  Everything outside of that is my business, done on my own breadboard, on my own time.  I'm not asking anybody to build or design it for me, just a simple answer to a simple question. 

I love all you good folks as much as anyone can from across a keyboard and mouse, but stick a fork in it, this one's done, see you in the next thread.

[ElectricDruid]

Lol, fair enough.

[Fancy Lime]

Sorry but this requires one final PSA for any newbies who might come across this thread in the future:

Sticking a fork in it is NOT a recommended remedy for hair in butt! If the issue does not resolve itself within 24 hours, please go see a professional about it.

[duck_arse]

Sorry but this requires one final PSA for any newbies who might come across this thread in the future:

Sticking a fork in it is NOT a recommended remedy for hair in butt! If the issue does not resolve itself within 24 hours, please go see a professional about it.

barber or proctologist?

[GibsonGM]

I love all you good folks as much as anyone can from across a keyboard and mouse, but stick a fork in it, this one's done, see you in the next thread.

It's not done until the hair issue has been resolved   

[Axldeziak]

It's not done until the hair issue has been resolved 

This fork should resolve any "hair in the butt" issues.

[duck_arse]

It's not done until the hair issue has been resolved 

This fork should resolve any "hair in the butt" issues.

wrong thread - da Vinci invented the fork should be in Chug Fuzz.
https://www.diystompboxes.com/smfforum/index.php?topic=130266.0

[edvard]

 
Good grief, I love you freaks!

[edvard]

OK, I did it a few weeks ago and forgot to tell you folks... It works.  Works fine, not perfect, but pretty OK.  Sounds just fine with all the controls at noon.  Just remember to put the James in front of the Framus; the other way 'round the volume goes WAY up when you turn up the mids.  Oh, and it's the "single bass capacitor" variant from TSCintheweb, FYI, and I didn't tweak any values from the defaults.  Someday I might try a Bax instead just to see how it sounds.  Or make an active version. 

Or not.