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 Email Don Mills at: dpasdedeux@gmail.com
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Tube Amp Topics and Thoughts
INTERACTIVE VOLUME CONTROLS FOR THAT "BETTER-THAN-BLACKFACE-TWIN CLEAN TONE TO DIE FOR"

Here’s a great bit on interactive volume controls from Gerald Weber’s book “Tube Amp Talk for the Guitarist and Tech”.

Let’s look at another example, the tweed Deluxe. This amp is very unique because the volume controls are not voltage dividers!! Did you ever wonder why all tweed Deluxes seem to have an audio pot with too fast a taper? The volume control in a tweed Deluxe works by “loading down” the signal coming from the plates of the preamp tubes!

If you are plugged into the instrument channel, the signal goes backwards through the microphone channel’s volume pot, through the microphone channel’s coupling cap, plate resistor, and filter cap to ground. You will get maximum mids in the instrument channel with the microphone channel’s volume control turned about halfway up. You will get a maximum midrange scoop with the microphone channel’s volume control turned full up. This would work the same if you switched channels and were plugged into the microphone channel and adjusting the instrument channel’s volume. 

This can be used to your advantage, especially if you have an A/B box. Set the normal channel all the way up and the instrument channel halfway up. Use an A/B box to select between the microphone and instrument channels.

Here’s what will happen: When you select the instrument channel, you will get a fabulous clean tone. Since the instrument volume is turned halfway, you are not really overdriving the instrument channel that hard and since the microphone’s volume control is turned full up, you are scooping out the mids in the instrument channel. This gives you that “better than blackface Twin” clean tone-to die for.

When you select the microphone channel (which is turned all the way up), you will get a fabulous lead tone. For one thing, you will be overdriving the output stage and because the instrument channel is halfway up, you will be boosting the mids as much as possible. This results in a thick, creamy, cello-like tone with incredible sustain.

Of course, there are many other settings between the two extremes described earlier that will give very usable tones. This is where experimentation with your guitar, your playing style and listening will reveal the possibilities.




THE HUGE DIFFERENCE IN TUBE TONE

Is there really that big of a difference between solid state and tube amplifiers?  Yes.  There is a huge quantifiable difference.  You physically hear a fuller sound being transmitted from a tube because a tube is transmitting the full audio wave of that sound.  Bruce Lusignan, professor of electrical engineering at Stanford University, and a man with 16 patents in signal processing has a pretty good idea of what he’s talking about.  He informs us that the laws of physics “actually favor analog transmission over digital”.  In other words the laws of nature favor tube sound transmission.  Analog signals reproduce the full sound waves of voices in the form of full electrical waves rather than waves sampled twice a cycle or hertz for a numerical approximation of the sound.  Yes, tube, or analog transmission, is radically more efficient for transmitting sound.  Solid state amps can only give an approximation of your tone at best.​

TUBES VS. SOLID STATE

​In Aspen Pittman's, "The Tube Amp Book", (p. 189).   Randall Aiken defines solid state as "a component that has been specifically designed to make a guitar amplifier sound bad.  Compared to tubes these devices can have a very long lifespan, which guarantees that your amplifier will retain its thin, lifeless and buzzy sound for a long time to come."


On FX pedals trying to emulate tube amps:  Why not just get a tube amp?

The only thing more important than your guitar is your amp.  An economical guitar will sound fantastic through a great amp, but the highest quality custom shop axe will sound like a toy through a low quality amp.  Where would you rather put your money?

Never switch on a tube amp without a speaker attached.  Never switch on a solid state amp with a speaker attached.

CHEAPER AND BETTER IN THE LONG RUN

A $1,500 top quality, hand-built, point-to-point wired  tube amp (with no printed circuit board) is cheaper than the brand name amp for $500, not counting FX pedals necessary to try to make it sound like a tube amp.  The $500 amp will last a  few years before it breaks, and is probably irreparable.  The hand-built amps of the 1950's are still going strong.  Let's see.  $1,200 / 60 years = $20 a year, $1.67 a month, 5 cents a day.