I think there is a fair amount of material on the web for electric guitar amps. Just need to spend a bit of time searching for it.
In essence, the key points that a layman needs to account for with tube amps is the much higher voltages, the presence of tubes in both the pre and the power amp, the model of tubes, the act of biasing at the recommended settings and the periodic replacement of tubes from time to time.
Another suggestion I can think of is to look up the online manuals of some tube amps as they do have general information that can be applied to all tube amps.
For example, from the Diezel website:
--------
Chapter One: Safety and Warranty
1.1 Safety warnings
We would like to stress the importance of the following points, for reasons of your personal safety, product longevity and product liability.
• Do not use the Amplifier in or near wet locations
• Do not store the Amplifier in damp or wet locations
• Do not operate the Amplifier on voltages other than those designated on the rear panel of the amplifier.
• Do not open the panels of the amplifier. No user serviceable parts inside.
Your Einstein operates on very high internal voltages, which may still be present after the Amplifier has been turned off and disconnected for a while.
• Do not use the Amplifier for anything other than its designed purpose: To
Amplify Electric Guitar Signals
• Do not use fuses other than those intended and specified for the Amplifier
• Do not use 2-conductor extension cords or anything other than 3-pole grounded outlets for this appliance. Your life may depend on it! Please observe the following points when transporting your Einstein: Einstein is a tube-powered amplifier; therefore it is sensitive to shock especially after playing the amplifier for a while. Please store and transport your amplifier gently and try to avoid extreme temperatures, which might produce condensation, resulting in moisture on internal components. Usually a 60 Minute acclimatization period is sufficient to ensure safe operation.
The amplifier should be stored in a controlled environment, and it should be transported in a suitable flight case. Make sure the amplifier gets transported in its normal operating position, not upside down or on its side.
The Einstein’s design incorporates a very potent power amplifier. It is configured to deliver satisfying guitar tones at most volume levels. In its normal operational volume level (75-80dB) it will provide beautiful tones with very little coloration. For reasons of your own safety, please do not run the amplifier above these levels for extended periods of time without wearing a hearing protection. Hearing Loss is a long-term ailment, and is not normally curable.
1.2 Warranty
Excluded from this warranty are all vacuum tubes and any abuse done to the
amplifier. Also excluded from this warranty are damages resulting from failing to follow the Safety Warnings mentioned in the section 1.1.
Chapter Two: Using Your Einstein
2.1 Mains Connections, Power and Standby
2.1.1 Mains/Connection to Power Outlet
Please make sure that both switches (Power and Standby) are in the off position before connecting to the mains circuit. Verify line voltage before connecting the power cord. Never start Einstein without connecting speakers to the proper terminals. (See 3.2.5)
2.1.2 Power up, Warm up, Standby off
First, turn the Power switch to on (facing up). The indicator light will turn on.
This starts the tube heating process. After about 40 seconds, the tubes should be sufficiently heated for normal operation. Your Einstein is then ready for operation and the standby switch can be turned to “run” (also facing up). Premature activation of the standby switch will lead to unnecessary tube stress and subsequent reduction of the power tube’s life span.
2.1.3 Power Tube Caution
Tubes are electronic components that function only with vacuum intact and under very high operating temperatures. Each tube has one or more heating filaments, much like a light bulb. These filaments heat up the anode of the tube. If you switch the standby switch to the “run” position before these anodes have reached their operating temperature (when the anode surfaces are not heated evenly), this causes undue stress to the tubes and their related components inside the amp. Always give the amp its much needed warm-up time, even if musical inspiration hits you with a full force.
2.1.4 Operating Temperature
It will take a little more time after warm-up until everything inside the amp is working in sync and to its fullest potential. A trained ear will notice a slightly warmer tone and better complexity in tone after playing the amp for a short while. It’s like stretching before exercising.
2.1.5 Power Tube Life
The power tubes of your amplifier are subjected to a certain aging process. Once signs of aging, such as unreliability or unusual noise, are detected, we suggest that you replace all power tubes at once. Matched tube sets age relatively evenly, so our experience suggests. This means that if one goes, the others are not far from meeting the same fate. The aging process manifests itself by a depletion of a thin layer of wolfram on the anodes. This can take anywhere from 6 month to 3 years, depending on the amount of use of the amplifier.
4.2 Pre-amplifier Tubes
The pre-amps are equipped with 12AX7 tubes in all positions. The pre-amp tubes are not designed to produce high power output. Therefore, their life expectancy is much higher than that of the power amplifier tubes. This is not to undermine their utter importance in overall sound and response of the amplifier. Also, annoying defects like crackling noises and low dynamics are directly related to defective pre-amp tubes. Like all other tubes, 12AX7 tubes come in many different gain stages, and offer a wide variety of tonal behavior. Our choice for production was made to ensure a wide variety of tones, with low noise and good reliability.
4.2.1 Microphonics and Bad Noises
The overall performance of pre-amp tubes is easily influenced by external mechanical factors. Malfunction in these external components will manifest themselves by a sudden, high-pitched feedback sound. The input stage is especially suspect to these phenomena. If one encounters microphonic tube behavior, then the first tube should be checked as a rule. Pre-Amplifier tubes can also cause a hum or other bad noises, like crackling or ticking.
Chapter Five: Power Amplifier
5.2 Power Amplifier Tubes
5.2.1 Function
As the name suggests, the power amp section is the part of the amplifier that produces output power, measured in watts. Preamp signals are sent to the power amp(s), which amplifies this signal to a level that is acceptable for loudspeakers. Guitar amplifiers utilize several different types of power amps, which differ in output power and tone. We chose the tube type power amplifier for its tried and true performance and familiar tonal behavior.
5.2.2 Selection
Diezel Co. installs the most reliable and best sounding tubes that are currently available in sufficient quantities. So it is possible that tube brand and tube type will change during production. You can fine-tune your Einstein by having different type and brands of tubes installed, however, it is imperative that the amp is biased properly. Einstein utilizes 4 power tubes, organized in 2 pairs with dual bias possibility. This allows use of 2 different pairs of power tubes, either the same or the different types. Yes, this means that in a 4- tube Einstein, you can mix 6550’s with EL34’s, or 6L6’s with KT88’s etc. Cool!
A quick and a general overview of the most common tube types for the Einstein:
EL34/6CA7: aggressive, slender low end, higher total harmonic distortion
Recommended bias: 30-35mA
5881/6L6: great tube for clean sounds, good blues tone, also strong bass and excellent clarity.
Recommended bias: 25-35mA 6550: very loud, very good dynamics, strong low end, amazingly percussive. Recommended bias: 40-60mA
KT88/KT100: similar to 6550, but very punchy with great clarity and warmth. Expensive. Recommended bias: 35-50m
5.2.3 Life Span
Power tubes last 1 to 3 years, depending on care, volume and frequency of use of the amplifier. If you use your amp only once a month, then the tubes will last much longer. Really. We have heard tubes that are over 10 years old, but it was not a good thing. Tubes age very slowly; slow enough for the artist to get used to the changing tone. To keep things fresh, and to keep your tube dealer in business, we recommend re-tubing, cleaning and biasing once a year if the amp is used frequently.
