silly tube question

casterway · April 2nd, 2008, 02:21 AM

Is there a simple explanation of what exactly the vacuum tubes function is in a tube amp?

NewOldStock · April 2nd, 2008, 02:24 AM

It brings the magic.

Tim Swartz · April 2nd, 2008, 10:28 AM

The basic function is to take an an AC signal and make it larger. In a guitar amp, the guitar's pickup produces an AC signal that goes through a bunch of tubes with the signal getting larger as it goes through each one. The signal is then converted into audio waves via a speaker.

superlightweigh · April 2nd, 2008, 10:32 AM

it also adds those delicious harmonic overtones along the way that make the sound so pleasing to the ear

maybe that's not their function, maybe it is?

marshman · April 2nd, 2008, 12:10 PM

Well, superlightweigh, I don't think it's technically their 'function' per sae--but if they didn't do it, we would probably all have abandoned these silly, antiquated things for proper transistors long ago, wouldn'cha say?

I guess to help answer the original question--each time the signal passes through a component, it gets a little weaker. Passing through a series of components, like a tone stack, really saps the strength out of our little signal. Sending it through tubes along the way help to maintain the signal 'strength' so it doesn't fade away into nothing.

Typical signal path for a 'simple' amp...

Input jack-->tube-->volume pot-->tube-->tone stack-->tube-->phase inverter-->tube-->power tubes-->output transformer-->speakers.

That would be roughly how a note travels through a tweed Fender Bassman, though there is a second input that I've ignored for the sake of clarity. The more complex the circuit, the more tubes need to ride along. Reverb a la BF Fenders require a tube and a half, and I think the tremelo circuit requires a whole tube.

Tremo · April 3rd, 2008, 03:25 AM

It amplifies.

casterway · April 3rd, 2008, 03:27 AM

Cool. Thanks guys.

April 2nd, 2008, 02:21 AM	#1 (permalink)
casterway Friend of Leo's Join Date: Jan 2007 Location: Aldergrove, British Columbia,Canada Age: 40 Posts: 3,038	silly tube question Is there a simple explanation of what exactly the vacuum tubes function is in a tube amp? __________________ If Meg White can call herself a musician, then so can I.

April 2nd, 2008, 10:28 AM	#3 (permalink)
Tim Swartz Tele-Afflicted Join Date: Mar 2003 Location: Michigan - Tweenst the Great Lakes Posts: 1,904	The basic function is to take an an AC signal and make it larger. In a guitar amp, the guitar's pickup produces an AC signal that goes through a bunch of tubes with the signal getting larger as it goes through each one. The signal is then converted into audio waves via a speaker. __________________

April 2nd, 2008, 10:32 AM	#4 (permalink)
superlightweigh Tele-Meister Join Date: Apr 2007 Location: Schenectady, NY Age: 43 Posts: 401	it also adds those delicious harmonic overtones along the way that make the sound so pleasing to the ear maybe that's not their function, maybe it is? __________________ Regards, Dan

April 3rd, 2008, 03:27 AM	#7 (permalink)
casterway Friend of Leo's Join Date: Jan 2007 Location: Aldergrove, British Columbia,Canada Age: 40 Posts: 3,038	Cool. Thanks guys. __________________ If Meg White can call herself a musician, then so can I.

April 2nd, 2008, 02:24 AM	#2 (permalink)
NewOldStock Tele-Holic Join Date: Mar 2003 Location: Northern Minnesota Age: 36 Posts: 560	It brings the magic.

April 2nd, 2008, 12:10 PM	#5 (permalink)
marshman Tele-Holic Join Date: Feb 2007 Location: SE PA Posts: 987	Well, superlightweigh, I don't think it's technically their 'function' per sae--but if they didn't do it, we would probably all have abandoned these silly, antiquated things for proper transistors long ago, wouldn'cha say? I guess to help answer the original question--each time the signal passes through a component, it gets a little weaker. Passing through a series of components, like a tone stack, really saps the strength out of our little signal. Sending it through tubes along the way help to maintain the signal 'strength' so it doesn't fade away into nothing. Typical signal path for a 'simple' amp... Input jack-->tube-->volume pot-->tube-->tone stack-->tube-->phase inverter-->tube-->power tubes-->output transformer-->speakers. That would be roughly how a note travels through a tweed Fender Bassman, though there is a second input that I've ignored for the sake of clarity. The more complex the circuit, the more tubes need to ride along. Reverb a la BF Fenders require a tube and a half, and I think the tremelo circuit requires a whole tube.

April 3rd, 2008, 03:25 AM	#6 (permalink)
Tremo Banned Friend of Leo's Join Date: Mar 2003 Location: Silicon Valley, CA, USA Posts: 3,803	It amplifies.