Gjika 10^n Operating Instructions

GJIKA POWERS OF TEN (10^n) Guitar Amplifier with Gainmaster & Cable INSTRUCTIONS:

Thank you for your purchase of a Gjika Amp. Here is what you need to know to get the most out of this original design, high-power, single-ended Class A guitar amp, and the accompanying Gjika Gainmaster, which allows you to get a cranked amp sound at any desired volume.


IMPORTANT: this is very important, did I mention this is IMPORTANT? Well it is, so listen up, you need to have surge protection on your amplifier, and the best way to do that is with a surge suppressor (like you use for your computer and other expensive equipment). Get a good one. I have information about that on my YouTube channel videos, if you want to know more. For the purposes of this instruction manual, it will suffice to say that if your amplifier is not protected by a surge suppressor, and damage from electrical surges occurs, the warranty is void, and any repairs will be made at your expense.

For optimal performance, get a Variac, and plug it into the wall outlet, then plug your surge suppressor into the Variac, and plug the amplifier, Gainmaster, and any other equipment you will be using, into the surge suppressor strip. The reason for a Variac is that you never know what the voltage is in the wall outlet you are plugging into. These voltages vary depending on what time of day it is, or where you live. The 10^n amp, Gainmaster, and most all other modern equipment you may be playing through, is designed to run at 120V. As a seasoned player, you will find that it is your responsibility to make sure that you provide these devices with the specified 120V. If you are using this amp overseas, you will need to use either a drop box or a Variac to provide the amp and Gainmaster with the specified 120V. If you are unsure of what to buy, communicate with me and we can find the proper solution for your specific needs.


This is also important, do not defeat your ground on the amplifier. If you get two amps, to play in stereo, then use a HumX adapter for one of the amps.

You will use the adapter that comes with the Gainmaster to avoid a ground loop hum occurring. If you choose to use a HumX, that is also acceptable.

TUBES: Save the boxes, note locations on the preamp tubes (12AX7s) if you choose to remove them. The reason for this is that I have selected them for tone and response for their respective positions.

Your amplifier comes equipped with two 12AX7 preamp tubes, which are pre-installed. It also comes with four KT77 power tubes, which are interchangeable, so don't worry about which one goes where, just install them according to proper tube installation techniques, and you are good to go.

Your tubes have been carefully selected for your Powers of Ten amplifier. If you decide to remove these tubes for any reason, please mark the locations of the tubes you have removed, so you can easily put them back where they go. This is only important for the preamp tubes (12AX7).

REPLACEMENT TUBES: if your power tubes fail, they must be replaced with a matched quad of power tubes. Tubes all will eventually fail, and must be replaced. When you need replacement tubes, it's best that you get tubes that are within the testing results on the packages that the tubes were originally packed with so SAVE THE TUBE BOXES. Again, when the time comes, you can contact me and I will help you get the right tubes for your 10^n.

The Gainmaster tube is a little different story, since so much rides on it, it is subjected to even more rigorous testing and only a small percentage of tubes are designated as being good enough sounding to be Gainmaster tubes, and for this reason, I recommend that you purchase them directly from me. I sort through hundreds of tubes to select the best-sounding tubes for the Gainmaster, so you get the great guitar tone that it was designed to provide. The good news here is that because of design factors in the Gainmaster, this tube will last a long, long, long time.


You do NOT need to replace any of the tubes in the amp or the Gainmaster (such as to use vintage tubes) because I have already tested these “Unobtanium” tubes in the amp and Gainmaster, and they do not generally appreciably improve the tone, and in most cases, are not as good sounding as the hand-selected modern tubes I designed the amp to work with. Most of the good stuff is gone, anyway. NOTE: I have the good stuff, and they are not what is in my personal pair of 10^n amplifiers. My amps sport the same tubes you received with yours.


You may decide to try to get different guitar tone using different tubes in the Gjika Powers of Ten (10^n) amplifier, but be sure to follow the following guidelines:

EL34 power tubes may be substituted for the KT77 power tubes that the amp comes with.

Do not use other tubes – KT77 or EL34 ONLY.

MATCHED QUADS ONLY. If one tube blows, it can be replaced, but the replacement must be carefully selected to go with the remaining tubes of the original matched quad. It is not recommended to mix and match tubes of different types, manufacturers, or to randomly select the tubes.

This amp is a high-current, Class A amp, and requires that the tubes be optimally selected for this type of circuit. The Gjika 10^n guitar amplifier works best with tubes that fall into a certain test range. That's why I recommend that you get replacement tubes from me, or check with me to make sure you are buying a good testing range for the amp. Having a spare set is not a bad idea.


The gold aluminum tube guard on the back of the amp serves the purpose of protecting your tubes, and the fan that is used to cool this high-power single-ended Class A amplifier. The tubes get hot, and should not be placed near fabric such as upholstery or curtains or placed up against a wall which will cause heat build up.

You will take the tube guard off to put your power tubes in. The tubes are packed in the right hand side (from the back) of the amp. You can operate the amp without the tube guard, but that is inadvisable, so I recommend that you keep the tube guard installed during all times when not changing tubes or cleaning dust from the inside of the amp or fan.

It is possible that the fan may build up dust, pet hair, etc, over time, so do be aware that you can just shine a flashlight in there once in a while to make sure everything is tidy inside, as the amp is open in back except for the tube guard, and things can get in there.

SPEAKER CABLE: Your Gjika Powers of Ten amplifier comes with a special speaker cable for connecting your amplifier to a speaker cab. The length is 5' long which is what I've found to be a good length for most players, but you may want a longer cord at some point, and you can contact me to get a longer cord, or to buy additional specific-length cables for use with multiple cabs. I recommend that you only use my cords with my amps.

It is also a good policy to always keep the cord ends plugged in the same direction, so mark the end that goes in the cab and always put that end in the cab. A zip tie works well for this. If you purchase a cab from me along with the amp, I will pre-mark the end of the cable with a zip tie.


The Gainmaster comes ready to go. It has it's own power cord, and therefore you may experience a ground loop hum, which will be eliminated by lifting the ground.

The Gainmaster is an in-line signal-shaping device I designed to work with my amps. It's main use is to obtain the cranked sound and feel of my amps at any volume, even at extremely low “bedroom “ levels. Used in this manner, practicing for long periods of time is less taxing on the ears, and your relationships with neighbors and housemates, obviously... but if you are in a position to turn up your Gjika amp loud, then the Gainmaster can be used to access scorching gain levels with tons of harmonic goodness. I designed it to work with my amps and I only sell them along with my amps.

More than likely, most other amps would not be able to accept the Gainmaster's high signal levels, because their front-end designs may not be up to the task. So, if you try to use it with other amps, you are on your own.

You will want to put devices such as treble-boosters, wah pedals, and Uni-vibes and the like in front of the Gainmaster. Time-based effects, such as delays and reverbs are placed between the Gainmaster and your Gjika amp.

The Gainmaster runs on a single 12AX7 tube and takes a one-amp fuse. Like any other device you would use in your rig, and depending on your power supply ground isolation, you would probably do best to lift the ground on the Gainmaster to avoid ground loop hum.


IMPORTANT: Make sure the amp is plugged into a cab before turning it on. You will destroy the amplifier's power transformer if you leave it on without a speaker hooked up to it, and void your warranty.




Two Raytheon-Style pointer knobs in front:

TONE on left:

VOLUME on right:

EQ switch in the middle of the two knobs:

Input jack on front

Begin experimenting with your amp's controls at approximately even settings (Tone and Volume) and start out low on the volume control. This amp is extremely powerful, be careful.


Power switch on the back:

DOWN is ON position.

UP is OFF position.


There are 3 jacks to plug in speakers to your amp.

One is labeled 16 Ohm

Two are labeled 8 Ohm

Plug in speaker cabs as follows:

One 8 Ohm speaker cab – use either of the 8 Ohm jacks

One 16 Ohm speaker cab – use the 16 Ohm jack

Two 16 Ohm speaker cabs – use the two 8 Ohm jacks

If you want to use two 8 Ohm speaker cabs, you will need to buy or build a series box, which is just 3 speaker jacks wired in series. You would plug both cabs into that box, and run a cable from the box to the one 16 Ohm jack on the amp.


Two knobs on the Gainmaster control the level and the gain. I will give you my favorite starting points – I set my level control around 1 o'clock, this should start you at level to your clean signal or slightly boosted. I set the gain control around 11 o'clock. These two settings should give you a good cranked amp tone from bedroom volumes to fairly loud volumes. For your maiden voyage, try your Gainmaster set this way, along with the amp's volume and tone settings at 9 o'clock, and the EQ switch in the down position. I generally leave this switch in the down position, unless I am turning the amp's volume and tone up past 9 o'clock

This is just a starting point for you to do your own experimenting.