I built this amp from a book called "The Guitar Amp Handbook" by Dave Hunter.

It is single ended, valve rectified & uses two 6V6GT's in parallel for about 10 watts. The clean sound from this thing is incredible. It runs through 2 Jensen speakers - an 8 inch & 10 inch. A simple tone control & bright/boost voice switch along with a switchable negative feedback loop gives lots of variables with it's sound.

All caps, pots, valves, sockets, knobs, tag strip, Hammond transformers & Jensen speakers were supplied by Evatco.        Thanks,    Tony Sturt

 

 

PROJECT - AX84 "HIGH OCTANE" Guitar Amplifier

 

The amp is based heavily on the AX84 Hi-Octane project with the layout and schematic from the Silvertone website "www.silvatone.bravepages.com". This was my first amp build and I highly recommend these two resources for DIY guitar amp builders. The amp required very little troubleshooting, sounds great and is not inherently noisy. It has a high gain preamp running two JJ Telsa 12AX7's with a single ended Class A EL84 (also JJ Tesla) driven power stage, good for around 7 watts. The transformers are Hammond 125ESE (O.T.) and Hammond 369EX (P.T). The chassis is an aluminium Hammond 16x8x2".The amp has a nice cleanish tone at lower gain settings but sounds best when driven moderately hard. I play both a Tele and Les Paul and the sounds from each are great (although I do prefer the humbucking pickups of the Les Paul through this amp). I'm still waiting on the front and back faceplates to complete the project.

 

Many parts including the transformers, chassis, knobs and some tools were sourced from EVATCO vial mail order and the service was first class- thanks.

 

 

          

 

***    PROJECT - AX84 Guitar Amplifier

 

       Select picture for enlargement. 

   

The technical run down is that it is an AX84 P1 (rev. 10), 5-7W single ended class A guitar amplifier head with valve rectification and a triode/pentode switch running an EZ-80 EI rectifier valve, 12AX7LPS pre-amp valve, EL-84 output valve, Hammond 369EX power transformer and a Hammond 125E output transformer all mounted in a Hammond aluminium chassis. All plans were supplied by www.ax84.com and most of the parts supplied by EVATCO.

It worked first time and winding the volume out it starts off clean and warms up nicely to a classic overdrive sounding distortion. Kicking in the triode/pentode switch gives the amp headroom that would enable it to hold its own in a band situation even with an enthusiastic drummer, just.

 

***    PROJECT - Here is a project sent in by one of our customers. The Items are (1) AKSA GK-1 Preamp and AKSA 55 Nivarna Plus Power Amp built into Hammond Chassis 1441-32BK3 and (2) a prototype 120W Ultralinear Power amp using 4 off KT88 Output Valves, 2 off 6SN7 Drivers and 2 off 6N1P as a Current source biased Cascode Diff Amp (on the PCB). The PCB Is from Curcio Audio Engineering. Transformer is Hammond 1650T.
 
    Select picture for enlargement. 

  

    New information has been received about the design and progress of the KT88 amplifier seen here.

    For the designer's comments, please click here.

        

         KT88 amplifier schematic

        

         Power supply schematic

 

 

 

                            

                                

***  PROJECT - Super (Dual) Class A Guitar Amplifier

The original purpose for building this guitar amp head was purely for recording but even at only 10-12 watts it has turned out the perfect stage tone and level. Firstly this amp is based on your classic single ended valve amp 

(eg. Fender Princeton) except that I have two output valves and two rectifiers in parallel for extra output (an
idea borrowed from Angela Instruments USA). Secondly you can switch between a pair of 6V6 or EL84 as your output valves. You can also choose one valve rectifier (5Y3) for a slightly softer sound or two rectifiers for higher plate voltages and a more tough tone. Along with a volume and fairly standard single tone control it has "Deep/Bright" switch which changes the cathode bypass capacitor on the first stage (which has a bit more gain than your standard Princeton) and  a switchable cathode bypass capacitor on the output valves for either a more spongy sound (without) or a tight full sound with the capacitor in circuit. This has turned out to be a very versatile amp for every situation, it plays and records beautifully and compares admirably to my AC30 and Fender Vibrolux for usable tone quality. For extra info contact m.hart@uws.edu.au. 

The good fellows here at EVATCO supplied the Hammond transformers and 80% of all the parts.