How do tube amps work?
- Thread starter stef89
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PFDarkside
of the Forum
Re: How do tube amps work?
Do you know how solid state amplification works or are you new to electronics in general?
Do you know how solid state amplification works or are you new to electronics in general?
Re: How do tube amps work?
I dont know allot about the technical side of things no.
I dont know allot about the technical side of things no.
Re: How do tube amps work?
Ive read that one and cant really find the answer to my question.
Ive read that one and cant really find the answer to my question.
Securb
One of Jerry's Kids
Re: How do tube amps work?
I would suggest picking up Dave Hunter's book. There is way too much information to be covered in a thread about how and when the tubes work. Especially when you get into the differences between Class A and Class AB amps
http://www.amazon.com/Guitar-Amplifier-Handbook-Understanding-Amplifiers/dp/087930863X
The simple dimestore explanation is the preamp tubes shape the sound the power tubes provide the amplification. But there is a lot more to it than that and all of your tubes have an influence on tone.
I would suggest picking up Dave Hunter's book. There is way too much information to be covered in a thread about how and when the tubes work. Especially when you get into the differences between Class A and Class AB amps
http://www.amazon.com/Guitar-Amplifier-Handbook-Understanding-Amplifiers/dp/087930863X
The simple dimestore explanation is the preamp tubes shape the sound the power tubes provide the amplification. But there is a lot more to it than that and all of your tubes have an influence on tone.
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Re: How do tube amps work?
The preamp tubes amplify (pre-amplify) the signal from the guitar, the signal is sent to the power tubes which amplify that signal to a much higher voltage level. The signal travels through the output transformer (converts high voltage low current signal from tubes to high current low voltage signal) and out to the speakers. That's over simplified but the answer to your question is in that article (I just checked) and it's explained much better than I can explain it.
Edit. Get yourself a book like Securb suggests if you really want to understand all the details. It's good advice. I should heed it myself instead of muddling through.
The preamp tubes amplify (pre-amplify) the signal from the guitar, the signal is sent to the power tubes which amplify that signal to a much higher voltage level. The signal travels through the output transformer (converts high voltage low current signal from tubes to high current low voltage signal) and out to the speakers. That's over simplified but the answer to your question is in that article (I just checked) and it's explained much better than I can explain it.
Edit. Get yourself a book like Securb suggests if you really want to understand all the details. It's good advice. I should heed it myself instead of muddling through.
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Re: How do tube amps work?
I'll second this, Dave's book is amazing and remains a reference even now as I build amps...
I'll second this, Dave's book is amazing and remains a reference even now as I build amps...
PFDarkside
of the Forum
Re: How do tube amps work?
Third the Hunter book suggestion, great reference.
We never learned about tubes in school, so it's a great, easy read that allows you to take your solid state knowledge and apply it to tubes. It's also written in simple enough language that even with limited technical knowledge you can get something out of it.
Tagging on Darg's response:
Essentially, your pickups provide a low voltage, low current signal. The preamp had several gain stages (usually half of a 12ax7) that begin to amplify that pickup signal to a larger voltage signal. Then, depending on amp design a tone control section is either in the middle or end of the preamp. This can be passive (cut only) or active (boost and cut). With vintage amp designs, the full frequency spectrum is too harsh for our ears, so at least a treble cut (tone) is used to knock down some of that treble. This amplified and filtered signal is fed to the power amp (which could be a number of different designs... Single ended, push pull, Class A, Class AB) and depending on this, you may have a phase inverter stage. (Mirrors the signal to feed to the "pull" portion of a multi tube push/pull amp). Finally the output transformer matches the impedance of the power tubes to the speaker, and in turn converts high voltage/low current to low voltage/high current.
That's simple, leaving a lot of things out and focusing on only a few amps, but most have a similar signal flow.
Third the Hunter book suggestion, great reference.
We never learned about tubes in school, so it's a great, easy read that allows you to take your solid state knowledge and apply it to tubes. It's also written in simple enough language that even with limited technical knowledge you can get something out of it.
Tagging on Darg's response:
Essentially, your pickups provide a low voltage, low current signal. The preamp had several gain stages (usually half of a 12ax7) that begin to amplify that pickup signal to a larger voltage signal. Then, depending on amp design a tone control section is either in the middle or end of the preamp. This can be passive (cut only) or active (boost and cut). With vintage amp designs, the full frequency spectrum is too harsh for our ears, so at least a treble cut (tone) is used to knock down some of that treble. This amplified and filtered signal is fed to the power amp (which could be a number of different designs... Single ended, push pull, Class A, Class AB) and depending on this, you may have a phase inverter stage. (Mirrors the signal to feed to the "pull" portion of a multi tube push/pull amp). Finally the output transformer matches the impedance of the power tubes to the speaker, and in turn converts high voltage/low current to low voltage/high current.
That's simple, leaving a lot of things out and focusing on only a few amps, but most have a similar signal flow.
Re: How do tube amps work?
Allright I understand more now, but I always hear about people use a boost pedal to make the preamp section "cook" and "push the front end of the amp" what does this mean. Just need a simple explanation, thanks for the advice on buying the book. But its not in my interest right now
Allright I understand more now, but I always hear about people use a boost pedal to make the preamp section "cook" and "push the front end of the amp" what does this mean. Just need a simple explanation, thanks for the advice on buying the book. But its not in my interest right now
Re: How do tube amps work?
a preamp has a certain amount of headroom. in other words, it can take X amount of signal before it starts to clip. by boosting the signal going to the preamp you can make it clip more. in tube amps this can be a good thing. in solids state amps it typically doesnt sound good
a preamp has a certain amount of headroom. in other words, it can take X amount of signal before it starts to clip. by boosting the signal going to the preamp you can make it clip more. in tube amps this can be a good thing. in solids state amps it typically doesnt sound good
PFDarkside
of the Forum
Re: How do tube amps work?
Here's an ultra simple graph:
Imagine the blue wave is your guitar signal at the input. Imagine the green wave is your "boosted" guitar signal. The amp input can only handle so much input voltage before it clips (distorts). In most applications this sounds really bad. Imagine intentionally distorting the signal from your DVD player... However, guitar signals sound more musical with a little distortion on them. What we consider a good "clean" guitar tone is actually distorted from a signal standpoint. By putting boost or overdrive in front of your tube amp it tends to increase this distortion which most guitarists like the sound of.
Additionally, when you turn your volume up on you amp, you are letting each gain stage hit the next gain stage harder, generating clipping/distortion. By boosting the front end of the amp you are getting some clipping out of that first stage which is a little different than clipping in later gain stages.
Here's an ultra simple graph:
Imagine the blue wave is your guitar signal at the input. Imagine the green wave is your "boosted" guitar signal. The amp input can only handle so much input voltage before it clips (distorts). In most applications this sounds really bad. Imagine intentionally distorting the signal from your DVD player... However, guitar signals sound more musical with a little distortion on them. What we consider a good "clean" guitar tone is actually distorted from a signal standpoint. By putting boost or overdrive in front of your tube amp it tends to increase this distortion which most guitarists like the sound of.
Additionally, when you turn your volume up on you amp, you are letting each gain stage hit the next gain stage harder, generating clipping/distortion. By boosting the front end of the amp you are getting some clipping out of that first stage which is a little different than clipping in later gain stages.
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Edgecrusher
Well-known member
Re: How do tube amps work?
Might want to clarify this a bit. Are we talking a master volume amp or a NMV amp? Turning the master up wont do anything to the preamp. If we are talking a non master volume amp. If you turn the volume from 1 to 2 you arent generating any clipping. In fact depending on the amp you might have to turn it up very loud until it starts to clip or distort. And not all clipping is generated in gain stages.
Or did you mean when you turn up the preamp volume?
Overall this is something that is better learned out of a book... another good book out there is Aspen Pittmanns "The tube amp book" also for general tube electronics information the old RCA tube receiving manuals are invaluable.
Might want to clarify this a bit. Are we talking a master volume amp or a NMV amp? Turning the master up wont do anything to the preamp. If we are talking a non master volume amp. If you turn the volume from 1 to 2 you arent generating any clipping. In fact depending on the amp you might have to turn it up very loud until it starts to clip or distort. And not all clipping is generated in gain stages.
Or did you mean when you turn up the preamp volume?
Overall this is something that is better learned out of a book... another good book out there is Aspen Pittmanns "The tube amp book" also for general tube electronics information the old RCA tube receiving manuals are invaluable.
PFDarkside
of the Forum
Re: How do tube amps work?
I think it's been discussed recently on this forum as well, what an important component the Phase Inverter can be in tone generation, where technically it's only job is to flip phase for Push/Pull configuration.
I need to get the Pittman book as well.
Based on the OP's feedback, just keeping it simple on all accounts. Thinking through a NMV Fender or Marshall, as the volume is turned up, more signal is allowed to pass and has the potential to clip downstream. I agree a true book can provide much more info than can be conveyed on a forum.
I think it's been discussed recently on this forum as well, what an important component the Phase Inverter can be in tone generation, where technically it's only job is to flip phase for Push/Pull configuration.
I need to get the Pittman book as well.
Re: How do tube amps work?
Since the OP isn't interested in full details from a book ... this is decent, covering the preamp section. Also has some links to details of some of the other components.
http://www.classictubeamps.com/preamp.html
Since the OP isn't interested in full details from a book ... this is decent, covering the preamp section. Also has some links to details of some of the other components.
http://www.classictubeamps.com/preamp.html
DrNewcenstein
He Did the Monster Mash
Re: How do tube amps work?
The trouble with books on given subjects is they have a minimum word count, which is generally much larger than your average College-level dissertation. They need "filler", so they go into details the average Curios George has no current interest in - the first guy to propose the idea, the evolution of the concept, the first one, the myriad improvements/refinements, the Big Names and how they got their start, quotes from famous users, the author's personal views, the extremely technical in-depth explanation of how the subject operates, ad nauseum.
There's rarely the "in-between" reference that gives an explanation that's "just deep enough" to convey the core elements, just the stuff for the person looking to get into the building of it.
The trouble with books on given subjects is they have a minimum word count, which is generally much larger than your average College-level dissertation. They need "filler", so they go into details the average Curios George has no current interest in - the first guy to propose the idea, the evolution of the concept, the first one, the myriad improvements/refinements, the Big Names and how they got their start, quotes from famous users, the author's personal views, the extremely technical in-depth explanation of how the subject operates, ad nauseum.
There's rarely the "in-between" reference that gives an explanation that's "just deep enough" to convey the core elements, just the stuff for the person looking to get into the building of it.
