P1 AX84 Guitar Tube Amplifier

About: I am a researcher/ scientist in pressure metrology, in my spare time i play guitar, building thing, breaking thing,

Tube guitar amplifier

Making a guitar amplifier may be slightly different to make an audio amplifier because it is devoted to the instrument so that the frequency range is designed for guitar. Selection of the type usually consists of a guitar amplifier of this type of tube and solid state, although the selection is very large relative to its taste and budget in your pocket
For the price this guitar amplifier guitar amplifier tubes dmore expensive than the amplifier that is made of solid state, well why the price is more expensive but still sought after by connoisseurs of electric guitars sound particularly likely because produced by an amplifier of this type is more striking and kicking hearts. Although the technology was seen absolete but the old-fashioned for this one is endless, until now many musicians, especially guitarists remained faithful to use the amp type in up to now
Due to expensive for a newbie is very difficult to obtain these types of amps, for that share a little experience in building an amp of this type, as already mentioned this technology is very long so it is not often found in new products but still only for connoisseurs of high end audio with the type of This amp is still a primary choice.
To make this amplifier is actually easier because the circuit is simple but it is necessary to use high voltage high caution. Basic knowledge of electronics becomes absolute, the right to read reference about tube technology into the entrance which is helpful to understand the use of tubes. Usually there is a specific naming for this example 12AX7 tubes, ef86, 6dj8, etc. el34.
The tube amplifier is actually working as anode and cathode using the heater triode reinforcement. Named because the tube is formed from a hollow tube usually made of glass and ordinary incandescent bulb has properties that can drop suddenly when age or wear  time runs out. For working voltage required 2 working voltage want good ac dc voltage, ac voltage to be used to power the heater is biased About a 6.3 V. For high voltage although it could use a low voltage tube usually works on 150 V with small currents
It required power transformers suitable depending on the class amplifier that we build class A, B, AB sometimes need to bigger transformer, to output tube amplifier output transformer also used to adjust kohm impedance to the impedance of some speakers as common as 8,4,16 and so on. so total  usually at least 2 transformers and 2 pieces of tube
Examples of the output transformer and power transformer can be seen from Figure 1.
Examples of artificial transformer can be seen in figure 2.
As there is a section of such amplifiers pre amp, tone control, power amp tube likewise, do not forget the power supply for high voltage dc. We will try to discuss the section, starting with the power supply.
Divided from the power supply transformer voltage produced two high-voltage and voltage for the heater. High voltage into the swtich stand by that point to control when we enter the high voltage to the tube. Usually when we first turn our amps of this type include turning on power to the heater voltage on the tube is marked with a turn on the tube, stand-by switch means turn on tube still has not given a high voltage so that the tube does not work at its operating temperature before it is done so that the lifespan of the tube more long time. rectifier or rectifier in the high voltage rectifier tubes can be performed by a diode rectifier or regular tube, which it surely will create different characters
usually every stage of reinforcement given a different voltage from the smallest to the largest preamp to power amp can be seen from the combination of resistor and capacitor filter for each voltage. Usually at this stage 12AX7 tube is used in which there are actually two channels so that the signal 2 times.

Step 1: First Stop

This project based on P1 from AX84.com, this project are intermediate to people that never experience to build using tube (valve) but beginer for whom experiencing,
basic need you have know to read schematic. in AX84 very cooperative how to build so i recomend that yo try to read all the document first and continue to build this amps

here are the links...


Step 2: Chasis Work

I made chasis from old PC cover, i fisthing to do you print the drill plan and cut it aconrding the plan,
you should make hole first it make easy to you but my hand bor are broken so i doit later.

Step 3: PCB

i dont have any turet / eyelet so i make PCB board to make easy, and i paint it orange color but i change to purple later on

Step 4: Wiring

1.AC switch and conector to wall adapter
2. transformator and heater
3. PCB
4. Potensio
5.Input jack
6.output jack

Step 5: Test

Step to test,
1. dont put tube fist , check heater voltage, and high voltage by switching stanby switch
2. if al voltage are corect, turn off everiting, place all tube, and speaker
3. hear the sound??
4. please connect your guitar...lol

Step 6: Sound Check


Step 7: Update

1 accident happened that I blow up the Power transformer when This amp connect to 4x12 cabinet speaker at each 8 ohm. the result it damage PT (power transformer) . when I change i have to change whole thing..I already finish make from head cabinet  to combo cabinet. the remaining i will make for firefly amp. I will post the picture for the current amp that I called "salsa amp"



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    8 Discussions


    5 years ago

    are you not worried about the boxes possibly catching fire if tubes over heat (probably a bit of a stupid question bit new to amp building)

    3 replies

    Reply 2 years ago

    No, there is almost no fire hazard. The sockets also conduct heat to the chassis, so it acts like heatsink. And dont worry about tubes getting hot, their operating temps are up to 150-200 °C


    Reply 5 years ago on Introduction

    There are no stupid question, I'm also new for building an amp. I never experienced for over heat(blow away) but i think its normal when this type of amp is get hot because the heater inside the tube. And there are no heat sink for tube also, sometimes some of amps cover 12ax7 because interference problem.


    Reply 5 years ago on Introduction

    I give link that shows when this amp used with another guitar effect that i build.