I need simple (preferably) pentode/triode or triode/triode preamp with bass, mid, treble and gain control. So simple, two valves. Input will be guitar. Output will be small SE 3W tube amp that I already have, or headphones. If both isn't possible then just SE amp. I expect tone controls are between valves, not at the end.
I want pentode first to pick up signal, because with low input signal is not likely to saturate triode behind. If there is some amount of clipping it's acceptable, it's for guitar.
So it's pretty common demand, if you know of schematic of something like this?
I want pentode first to pick up signal, because with low input signal is not likely to saturate triode behind. If there is some amount of clipping it's acceptable, it's for guitar.
So it's pretty common demand, if you know of schematic of something like this?
Moved to I & A per forum policy regarding guitar amps.
How about this:
An externally hosted image should be here but it was not working when we last tested it.
If gain adjustment is after first voltage amplifying stage, then a cathode follower must be added between volume potentiometer and tone control stage.
Tone control stage reguires steady source impedance which volume potentiometer is not.
Why do you want the volume control before tone stage ? I see no difference if it is after tone stage.
R5 and R5 form 500 k treble adjustment potentiometer (now on middle position), R7 and R5 is Mid. and R9 + R10 is Bass.
Tone control stage reguires steady source impedance which volume potentiometer is not.
Why do you want the volume control before tone stage ? I see no difference if it is after tone stage.
R5 and R5 form 500 k treble adjustment potentiometer (now on middle position), R7 and R5 is Mid. and R9 + R10 is Bass.
Ok.
You mean R5 nad R6, R7 and R8?
How about limiting end values of pots with additional resistors? Is it ok if pot goes 0R at end positions?
How about gain after tone controls?
An externally hosted image should be here but it was not working when we last tested it.
Judging by your posts, I'm a bit surprised that you're even asking. It seems to me that you know what you want and how to find/design it.
What you've shown there is essentially a standard Fender pre-amp, which is what I was going to suggest in the first place. It's simple and proven. Add a voltage divider with a pot on the bottom to control your output level and that should be all you need.
What you've shown there is essentially a standard Fender pre-amp, which is what I was going to suggest in the first place. It's simple and proven. Add a voltage divider with a pot on the bottom to control your output level and that should be all you need.
Sorry for misprints. Yes, R5+R6 Treble, R7+R8 mid, R9+R10 bass. All pots 500 k linear.
Without limiting resistors at the end of potentiometers the max. lift/attenuation is some 15 dB.
The frequency response of your circuit (=Fender) is confused and hazy.
This is not a real tone control, it is just a "tone control".
Different controls have interaction.
Adjusting bass will effect to treble etc. Also there is not real flat position.
In my example all the these defects are avoided.
Without limiting resistors at the end of potentiometers the max. lift/attenuation is some 15 dB.
The frequency response of your circuit (=Fender) is confused and hazy.
This is not a real tone control, it is just a "tone control".
Different controls have interaction.
Adjusting bass will effect to treble etc. Also there is not real flat position.
In my example all the these defects are avoided.
vasko, do you want to be able to overdrive this preamp? You mention clipping being okay, but do you want it? You said you want 2 valves, if you want 2 tubes you would have 4 valves. You could add a classic DC coupled cathode follower pair as the last stage to get some overdrive. It has a second benefit of giving you a cathode follower to drive into "unknown" loads outside (the cathode follower is more suited to driving heavier loads, low impedance).
This however is the tone control (commonly known as a tone stack in the MI industry) through long experience that has been found to work the best for electric guitar, that or the Marshall variation. The design and implementation are not accidental. Variations on the Baxandall work well with acoustic guitar and not so well with solid body electrics IMLE. So I guess the question to ask is what kind of guitar will be used with this pre-amp.
Here is a very good tone stack calculator on Duncan Amps: http://www.duncanamps.com/tsc/
As I wrote in first post pentode/triode, or triode/triode preamp. So one tube, two valves. This preamp will pickup signal from guitar, and will be always first in chain. No OD pedal will be used.
Can't really go wrong with any of the Fender or Marshall variants, should you not like the one you have chosen usually it will be just a few components that need to be changed to implement a different variant.
Since it is a Strat I would probably go with the Fender E or modern variants, beyond that it is a matter of (changing) preferences.
Download and install that calculator, also be aware that there is a variant called the Dumble which is essentially the 3 control tone stack implementation with some additional toggle switches to allow critical component values to be changed.
Since it is a Strat I would probably go with the Fender E or modern variants, beyond that it is a matter of (changing) preferences.
Download and install that calculator, also be aware that there is a variant called the Dumble which is essentially the 3 control tone stack implementation with some additional toggle switches to allow critical component values to be changed.
So you want only a clean amp? If not, you can increase the cathode resistor of the second valve to push the bias point closer to cut-off to get a bit of smooth clipping coming in.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.