I saw the threat " Extreme Peavey RAGE mod!" - which is outdated.....
For upgrading a transistor guitar amp I recommend:
- use 2 op-amp systems, often already build in in many newer amps. You need nearly the full gain of both. The 2 systems are often placed in a single case - like the TL072.
- a single 12AX7 is nice enough for heavy tube distortion. Place it after 2 op-amps. You need around 1 to 2 Volts AC signal nearly undistorted to drive the tube stage.
- the voltage of many design like the "real mctube" is too low for a good sound. Use 150 to 200 Volts DC anode voltage - but be carefull.
- use the in build EQ of the amp, be cautious not to overdrive it, because this mostly sounds bad and ruins the sound of the tube stage.
If you copy the overdrive stage of a known amp according to the schematic of the manufacturer: Dont be surprised if it does not sound. Most of the published schematics seem to intentionally uncorrect. If you can, measure the resistor and capacitor value of a working amp. Tell us what you got. If you dont have access to an amp tune around with the values in the tube stage until you found the sound.
You even can build a tube pedal in this way. You need
- a dual op-amp like the TL072
- a 12AX7
- a transformer (supply) 12 Volt DC to drive the tube heating and the op-amp (with virtual ground)
- a transformer for anode voltage, very simple if you can find a transformer with secundary 110/120 Volt AC - that gives you around 150 Volt DC anode voltage.
For modern sounds use at least a vented box 12 inch speaker or a vented box dual 10 inch speaker. Even if your output is only 5 watts RMS....
- success -
https://homerecording.com/bbs/images/icons/icon3.png
For upgrading a transistor guitar amp I recommend:
- use 2 op-amp systems, often already build in in many newer amps. You need nearly the full gain of both. The 2 systems are often placed in a single case - like the TL072.
- a single 12AX7 is nice enough for heavy tube distortion. Place it after 2 op-amps. You need around 1 to 2 Volts AC signal nearly undistorted to drive the tube stage.
- the voltage of many design like the "real mctube" is too low for a good sound. Use 150 to 200 Volts DC anode voltage - but be carefull.
- use the in build EQ of the amp, be cautious not to overdrive it, because this mostly sounds bad and ruins the sound of the tube stage.
If you copy the overdrive stage of a known amp according to the schematic of the manufacturer: Dont be surprised if it does not sound. Most of the published schematics seem to intentionally uncorrect. If you can, measure the resistor and capacitor value of a working amp. Tell us what you got. If you dont have access to an amp tune around with the values in the tube stage until you found the sound.
You even can build a tube pedal in this way. You need
- a dual op-amp like the TL072
- a 12AX7
- a transformer (supply) 12 Volt DC to drive the tube heating and the op-amp (with virtual ground)
- a transformer for anode voltage, very simple if you can find a transformer with secundary 110/120 Volt AC - that gives you around 150 Volt DC anode voltage.
For modern sounds use at least a vented box 12 inch speaker or a vented box dual 10 inch speaker. Even if your output is only 5 watts RMS....
- success -
https://homerecording.com/bbs/images/icons/icon3.png
