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Author Topic:  Tubology 101
Don Mogle

Fort Worth, TX, USA
Post  Posted 29 Dec 2017 10:40 pm    
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Hey Everyone,

With so many people out there using or thinking about purchasing a tube amp, I thought it would be a good idea to have a site where somebody could go to receive some basic education about tubes, tube amps, how to troubleshoot amp problems, etc.

I came across these videos and thought they'd be educational. Feel free to add any other sources you know of that may be of interest to other tubologists out there...



Phil Bradbury (Little Walter Amps) talking about power tubes in his educational series…


Phil Bradbury talks about Tube Amps…Power Tubes, Preamp Tubes, etc.


Phil Bradbury on Octal Tubes, microphonics, tube quality, tube preferences, etc.


Vintage video of an RCA tube factory…good basic knowledge of how tubes work and were made…


Journey to the Center of a Tube!


Here’s Uncle Doug talking about basic tube topics more technical in nature but really good information…


Troubleshooting Tube Amps…


What microphonic preamp and power tubes sound like…


Phil Bradbury talking about tone stacks…how to set the tone controls, etc.


Here’s Steve Carr talking about the black art of reverb…troubleshooting…theory, etc.


Steve Carr on the tube substitution and theory continued…


Steve Carr shows how to properly change tubes (good nuggets of information)


Six Preamp tubes compared (a shootout) in a Marshall amp…Amplified Parts video


Guitar Tone: V-1 Tube Rolling/Preamp Tube Comparison—Mesa, Telefunken, JJ Gold, etc.


Gerald Weber--tube amp seminar for novices. Good basic information in a four-part series. This is the first session. From here, you can link to the other three sessions.


Here's a rundown/comparison of 12AX7s recently posted to the Forum...


Last edited by Don Mogle on 30 Mar 2018 7:43 pm; edited 4 times in total
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Don Mogle

Fort Worth, TX, USA
Post  Posted 30 Dec 2017 6:19 am     Notes from the Tubestore
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What Makes A Good Tube?

The musical detail or ability to reproduce the sound of the instrument is a key factor in assessing a tube for guitar amplifiers. There is no perfect tube available. Each one has strengths, weaknesses and certain factors that contribute to its overall ratings. Usually a compromise is arrived at in the search for premium tone.

All tubes will exhibit some degree of microphonics. Microphonics do not mean that a tube is unusable. You just have to screen them a little closer and determine where they are best suited for use. Input pre-amps are the most sensitive areas of the amplifier. When used in this application most tubes will generate some noise if you tap on them with a pencil during operation. Keep in mind that doing so can actually damage the tube and make it more microphonic or cause it to fail if you hit it real hard. Although they are screened prior to shipment a tube is an electromechanical device and can be damaged during shipment. A microphonic tube will ring, howl or produce general feedback problems. It will be more noticeable at louder volumes or when used in close proximity to a speaker, typically in combo amps. If the tube has good tone at lower volumes and is free from unwanted noise, you use it in a less sensitive part of the circuit, such as tone recovery or phase inverter applications.

Noise is more of a problem than microphonics. A noisy tube will make random popping noises, crackle occasionally or just hum. All tubes have a certain noise floor; this is the inherent background noise that the tube makes in operation. Typically, you will notice this as a soft hiss or "white noise". Tubes designed for high gain can exhibit more background noise. Other components can cause noise problems that may be blamed on a bad tube. Plate resistors are notorious for causing hiss and crackling as they age and begin to fail. A new tube may better amplify these defects, so try substituting another new tube to be sure of the source of the noise.

(Source: The Tubestore)
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Jack Stoner

Inverness, Fl
Post  Posted 30 Dec 2017 6:47 am    
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I started in electronics, in 1955, when there were only tubes. I got my Ham radio license (W5DVO) in 1960 and all ham gear was tube.

Lots of theory and perceptions of tubes and how they work or what they do. Which ones are better or better suited for a particular application or circuit, etc. Some is fact, others are not (or marketing hype).
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Steve Mueller

Ohio, USA
Post  Posted 1 Jan 2018 10:55 am    
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That's great info, stated clearly. Thanks!
2016 Williams D12 8 x 8, 2015 Williams D12 8 x 8, Milkman Pedal Steel Mini, Li'l Izzy, Earthdrive, 2008 Gretsch 6120
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Michael Butler

California, USA
Post  Posted 1 Jan 2018 11:11 am    
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i didn't see it so i'll add this link. updated today!
franks electron page


play music!
please see my Snakeskin's Virtual Music Museum below.

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Mike Scaggs

Nashville, TN
Post  Posted 3 Jan 2018 5:27 am    
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Go visit Uncle Doug on YouTube. He has a lot of good knowledge and is well suited for folks who are interested in vacuum tube amplifiers.

Everything affects everythng

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Don Mogle

Fort Worth, TX, USA
Post  Posted 12 Jan 2018 6:19 pm     New Site
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Thanks to Mike Scaggs for this site...a ton of information on tubes and more!

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Jim Sliff

Lawndale California, USA
Post  Posted 15 Jan 2018 3:49 pm    
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I don't have the patience for videos so I don't know if these were covered.

One thing first-time (and many long-time) tube amp owners are not aware of is the need to have the amps serviced periodically. High-voltage electrolytic capacitors have a life expectancy of roughly 15 years (less if an amp is stored for long periods) and can blow without any audible OR visual warning.

Many vintage amp buyers end up with amps that have never been serviced (or haven't been in FAR too long), turn them on and end up with problems as serious as a fried power transformer.

manufacturers have never made a point of service needs, figuring most new amp buyers won't keep them long enough. Plus warranties expire long before caps fail.

The other problem is something that concerns potential DIY "amp techs", and that's safety. In many amps those same caps can hold a deadly charge for a very long time, even with the amp unplugged. Many would-be techs get a serious shock because they were unaware of how to safety discharge capacitors - and others have died.

Good things to be aware of.
No chops, but great tone
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