Tube Active Tone Stack??

[TIMBO]

Hi guy's, I sure this may have come up and then died a horrible death, as it is not something that you see in valves amps. I was thinking that if we can make tube FX loops,tube reverbs,tube distortion FX, etc. Can a signal be put through a circuit to create the bass and then through a tube (one triode) to enhance (amplify) the sound then through a pot to increase/decrease the level and the same for the treble.I ask as it seems to be a common problem with different TS as they tend to suck a lot of volume out of an amp. 

[kagliostro]

Weber has a schematic that do that, but people who tried it were not satisfied

https://taweber.powweb.com/store/modkits.htm#toneamp

Tone Control Amplifier

This is an active tone control. In other words, it is a tone stack with gain. A dual triode and all other parts are included in the kit. Using an active tone stack will give you a lot more range on the bass, mids, and treble control.

if I'm not wrong something like this was discussed in the past here on the forum

K

[tubenit]

Timbo,

As I understand it, a true Baxandall tone stack somewhat is tube driven.

The original Carolina Blues Special that I did used a tone stack idea from KOC's TUT book in a Soma18 schematic that he had.

It is a VERY low insertion loss tone stack & since the treble is directly integrated into the cathode resistor/cap section ........... it somewhat meets the idea that you suggested of tube driven and low insertion.

with respect, Tubenit

[Jack_Hester]

How about these:

http://home.comcast.net/~stphkeri/tone_control.html

Particularily, the paraphase tone stack.

Jack

[HotBluePlates]

As I understand it, a true Baxandall tone stack somewhat is tube driven.

Right.

The difference between it and the James is that the Baxandall circuit its inside the feedback loop around a tube gain stage. When you adjust the controls, you change the nature of the feedback and therefore the gain of the stage. That's what makes it active.

If you want a multiband active EQ, look at the Super Twin Reverb. The triode section of the 6CX8 is driving an active tone control circuit. The downside is the need for the tapped pots and multiple inductors. But in general, this circuit works by balancing how much signal is bled over from plate and cathode outputs of that triode, and because of how the tapped pots make the signal appear relative to ground, can provide boost as well as cut.

You can have active tone control stages, but you might gain as much or more output by simply using that triode (or triodes) as gain stages. There's no free lunch, and all circuits generally throw away some portion of the signal to make other portions appear "boosted". Even the Baxandall or other feedback tone circuits simply cause less feedback (or different feedback) to happen to appear to boost a signal.

[kagliostro]

I've find this link with the description of a single tube active tone control

and it uses a tone control that looks similar to a baxandall

http://www.angelfire.com/electronic/funwithtubes/Amp-Tone.html

Active tone control with a triode. The lower input terminal is grounded. The upper input terminal goes through a 470 k ohm resistor to ground. The upper input terminal also goes through a 110 k ohm resistor to one end of the bass pot, 500 k ohm linear. The other end of the bass pot goes through another 110 k ohm res to the output terminal. There is a 0.01 mike cap connected from the wiper to one end of the pot. There is another 0.01 mike cap connected from the wiper to the other end of the pot. The wiper of the pot connects through a 150 k ohm res to the grid of a triode, 12 A X 7. The upper input terminal also connects to one side of the treble pot, 500 k ohm linear. The other end of this pot connects to the output. The wiper of the pot connects through a 68 k ohm res then through a 100 pf cap, in series, to the grid of the triode. The output terminal connects through a 0.47 microfarad capacitor to the plate of the triode. The triode plate also goes through a 100 k ohm resistor to B plus. The cathode of the triode goes through a 1.8 k ohm resistor to ground. There is a 100 microfarad cap in parallel with the 1.8 k resistor.

and is strictly similar to this one that uses a pentode



http://home.comcast.net/~stphkeri/NegativeFeedbackTone.pdf

from the link previously posted

http://home.comcast.net/~stphkeri/tone_control.html


K

[TIMBO]

Thanks guy's, This is some where in the ball park of what i was thinking 

The schem below is more of what i was thinking but do not take it as anything other than an idea, cause i am no technical engineer in ANY way.
I have trouble just trying the get the link to work 

 http://www.interfacebus.com/Glossary-of-Terms-Base-Control-Design.html
http://www.interfacebus.com/Glossary-of-Terms-Treble-Control-Design.html

This part is a whole bunch of numbers that i'm sure that will get someone excited  it leaves me
 Why aren't TS active,I think that the cost of parts and that TS with lo loss design out weight the trouble. 

[kagliostro]

Give a look to this one

http://www.angelfire.com/electronic/funwithtubes/Amp-Tone-A.html

May be using 2 x 6ac10 tubes ...........

Potential 10 band equalizer. The input goes through a 33 k ohm resistor to the grid, pin 2 of a 12 eh X 7. The output connects through another 33 k ohm resistor to the other grid, pin 7 of the same tube. Each grid goes through its own 470 k ohm resistor to ground. The two cathodes, pins 3 and 8, are tied together and go through a 110 k ohm resistor to minus 150 volts. Each plate, pins 1 and 6, goes through its own 100 k ohm resistor to plus 150 volts. The second plate, pin 6, goes to the grid, pin 2 of another 12 eh X 7. The plate of this tube goes to plus 150 volts. The cathode goes through a 100 k ohm res to minus 150 volts. The cathode also goes through a 1 u f cap to the output terminal. Returning to the first tube, there is a long line extending outward to the right from pin 7, grid. There is a line from the other grid, pin 2, that goes downward and to the right under the tube symbol. This line extends as far right as the line from pin 7. There are 3 pots between the two lines. The top of each pot connects to the upper line from pin 7. The bottom of each pot connects to the lower line from pin 2. Each wiper will be described individually. The wiper of the left pot goes through a 0.18 uf cap then another 0.18 uf cap to the grid, pin 7, of another 12 eh X 7. The grid goes to ground through a 100 k ohm res. The plate, pin 6 goes to plus 150 volts. The cathode, pin 8, goes through a 120 k ohm res to minus 150 volts. The cathode goes through a 10 k ohm resistor to the junction of the two 0.18 uf caps. The wiper of the middle pot goes through a 0.0022 uf cap then another 0.0022 uf cap to the grid, pin 2 of the same 12 eh X 7. As in the other tube the grid goes to ground through a 100 k ohm res. The plate and cathode are connected the same as in the previously described tube. The 10 k ohm res from the cathode, pin 3, goes to the junction of the two 0.0022 uf caps. The wiper of the right hand pot goes through a 270 pf cap then another 270 pf cap to the grid, pin 7, of another 12 eh X 7. All other connections are as previously described. The writer believes that there are supposed to be 7 more circuits with two capacitors, 3 resistors, and a triode, to make up a 10 band equalizer.

K

[TIMBO]

WOW K, thats FANTASTIC  where do you find this stuff. It would be worth a try,thats for sure.Thanks

[kagliostro]

Pay attention I just realized that there is a B+ (150v) but also a B- (150v)

K