TREBLE CUT 3 POSITIONS SWITCH

[Colas LeGrippa]

Hi,

I would like to incorporate a 3 positions rotary switch to one of my amps that would cut ''highs'' to 3 degrees.  Actually, the amp has no tone stack ( was built like that ) but has a cathode follower. What would be the best way to do it ? 

Colas

[chocopower]

maybe something ala Vox Cut control?
instead the pot and the cap, you can instal 3 caps in the rotary switch and a trimer to dial the "cut" intensity...

[tubenit]

Just to add options to consider.  You could also have a mini-toggle spdt with center off.  The outside caps become paralleled to ground giving different values of dropping treble to ground.

Inexpensive, simple and doesn't take much space.

With respect, Tubenit

[kagliostro]

Other options:

a: the 220p connected that way prevent pop

b: This is the solution I like more, full range control, one knob, two cap (for bass control)

Kagliostro

[echuta13]

I'm wondering if you could take kaliostro's b. circuit and run it in parallel with a Princeton 5f2a tone control (or Magnatone 421 tone control)  on a dual 1 meg pot for some bass cut/treble boost and vice versa.   

[Colas LeGrippa]

I have hooked up 3 caps of different values from signal to gnd and it sucks away all the mojo from my amp. What I did is swapped the .022 last coupling cap to the power tube for a .1 .
Nothing is sent to gnd and I keep the magic of the amp. What I will do now is put a switch so that I could send the signal through a .022, .047 or .1 uF to the power tube, for treble control ( in fact, it is bass control, high frequencies passing through any of those ).   


Colas

[kagliostro]

I think you can try with solution b, varying the value of the two caps with the max and min value you prefer

other way you can use solution a, whit the number of cap you want, remembering that if you connect one cap directly (the 220p cap in the image) and use the switch to put the other cap in parallel, the circuit is less prone to pop

if you use only 3 cap and one is connected always and the other go in parallel with the switch, instead of a rotary switch you can use a very little ON/OFF/ON switch

in center position only the cap that is connected always is on (the center of the switch isn't connected), and in the other position one of the other caps is add in parallel

Kagliostro

[tubenit]

What I did is swapped the .022 last coupling cap to the power tube for a .1 .

This is what I'd be tempted to try given the approach that you're defining. I have not done going into a power tube grid, but have done this into a preamp grid without popping when it's switched.

for a push/pull ......... you'd do this with a dpdt

With respect, Tubenit

[Colas LeGrippa]

and what is the purpose of the 4,7M grid leak resistor between the two caps , instead of being right before the grid stopper ?

Colas

[tubenit]

what is the purpose of the 4,7M grid leak resistor between the two caps , instead of being right before the grid stopper ?

I think that it helps eliminate the "popping".  I've only tried it like drawn so I don't know if other methods would work?

This schematic portion I drew would presume a 220k grid resistor to ground or some type of master volume going into the power tube  ..........  in addition to what I drew.

I might point out that you did NOT indicate what type of amp this is. Without knowing that or seeing a schematic, I can only give
you an incomplete answer.

With respect, Tubenit

[Colas LeGrippa]

I might point out that you did NOT indicate what type of amp this is. Without knowing that or seeing a schematic, I can only give
you an incomplete answer.

Good morning!

No matter what type of amplifier it is, I just found it unsual to draw it the way you did it. But I find interesting the parallel/series caps hooked up to a normal switch to give the result I want, instead of using a rotary switch ( that I would have to buy ). For the non-popping circuit, I'll try different things, starting by yours and get back to you with the results.
The amp we're concerned about is a mix of a super champ ( power section ) and the preamp of a JCM800 (2204). The tone is totally what I have expected ( not the heavy rock one but the blues one ). When we mix different amp circuits, we gotta make some small adjustments so that the overall tone is well balanced. I do not use no tone stack in any amp I make ( I prefer adding a bassy coupling cap to level the highs rather than sending the highs to the garbage.... (chassis)  to level the bass, so I keep ALL THE MOJO of my amp). I will make a short video this week-end if my son is available and post it on YOUTUBE, to give an idea of the tone and guts it has, with its tiny OT and ultra simple circuit ( that we can see through the plexiglass used as the under plate ).   I will post the link here as well, that's for sure!

Best regards

Colas

[tubenit]

I will make a short video this week-end if my son is available and post it on YOUTUBE, to give an idea of the tone and guts it has, with its tiny OT and ultra simple circuit ( that we can see through the plexiglass used as the under plate ).   I will post the link here as well, that's for sure!

Great! I look forward to it! I have always enjoyed your playing.

Thanks, Tubenit