For those without the benefit of an engineering or technical background, you may benefit from a series of free 'gear lesson' videos I'm doing for OldToneZone.

The series is called "Understanding Tube Amps", and the first 4 installments are available, with more to come.

It is my best attempt to explain how tube amps work in basic, plain English, without resorting to technical engineering terms that will only make it hard to understand.

You can watch the YouTube playlist here: http://www.youtube.com/view_play_list?p=2D0A1CC3FC96F1CA

Or watch them and comment at OldToneZone.com here:
http://www.oldtonezone.com/category/understanding-tube-amps/


I hope some people find it useful, and are able to better use their gear after watching

Thanks for posting this. Good videos Anthony......... Mike

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The blues ain't nothin but a good man feelin bad.

Anthony, i wanted to ask about "non master volume" tube amps. now, i'm technically going to answer my own question, and hopefully you can verify or correct me where i'm wrong.

consider the fender Pro Junior in this example, or any simple tweed circuit like a Champ. also consider 12ax7 preamp tubes.
i'll start by quoting your comment from the Part 4 video, because it actually helps answer my question a bit (i just hope to clarify the conclusion i got from it)...


thedonace213 asked: "I have a Fender Super Reverb Reissue so it doesnt have a "Master Volume" in what ways does that differ from the way this lesson explains the whole amp/volume distortion?"

you responded: "That simply means that the master volume is always on "10" or all the way up.  Because you cannot turn the master volume down, it's not possible to overdrive the preamp tubes and use the master volume to keep the overall volume lower by cutting the amount of signal to the power tubes. "


ok so, i believe i see what is going on in a non master volume amp. in simplest terms, as i turn up the volume knob (the ONLY volume knob) on the amp, the preamp is raising the signal, and then since the "master" is wide open, the power amp is also raising signal likewise.

so, what i gather is that in an amp such as the Pro Jr or a Champ, the first stage to clip/overdrive is the power section. as the amp volume nears max, or maybe like 9:00, the preamp is now starting to clip and distort. so you basically have 2 layers of distortion at max volume, which explains why it would "roar".

i believe you may agree with this. i almost feel silly asking because it seems so simple, and in my mind i feel i'm right, but a question unasked is a dumb question.
i'd be curious to know at what volume point in a Pro Jr does the preamp start clipping. but in light of that, i'm just gonna play the darn thing and not think much over it, hah.


btw, i am not thedonace213 if anybody is wondering

Your instinct are correct in that both stages of the amp would distort. As to which stage would distort first, that's something I'm not clear on. Some of this has to do with which preamp/power tube combo you have.

Some preamp tubes distort faster, or at lower volumes than others, so this would affect what's being pushed to the power tubes as well.

My next video will address this further, the relationship between distortion and volume.