Amp gurus...do preamp tube covers change an amps sound/tone?

[Gooseman]

How is this topic still alive!

 

[fek]

I was discussing this subject with Andy Marshall about 10 years ago and he said something like ... Not only the tube it's self but how it reacts to the other tubes and the other components in relation to distance .... and he implied it was more than just for noise. He felt it was very important in the way it reacted to the other tubes .... that is why on the Flexi all the preamp tubes are under one cover.

Or how a Peavey Classic series or 5150 have the pre's are under a metal cage with a piece of rubber (or whatever it is) holding them all in place. The Classics and 5150's have there place as solid gigging amps with good tone. Again I like the tube covers off.

 

[Anonymous]

And my ham sammich taste alot better too!!

 

[JerryP]

They're like tube condoms. Of course the playing feel is going to be more sensitive with them off.

And I thought they were just scared of the dark inside the covers....

You have a bottle with a vacuum inside.
In that vacuum are magnetic/metallic plates.
An electrical charge is introduced on the cathode.
Electrons flow from positive to negative, the anode.
Electrons flowing from the cathode to the anode create current.
Nothing to do with being covered or not.

Having said that, one might argue the point that heat is better dissipated with the covers removed. If the tube is cooling faster, it may discharge current at a more efficient rate. There is no such thing as tube "osmosis" as some people are trying to argue. With flow of electrons, a magnetic field is created. With heat, glass expands a little bit too, making the vacuum volume a little larger, then back to size. This to may bring on some inefficiencies. The fields though, attracts other nasty stuff, like RF, UHF, VHF signals. The an aluminum shield, this offers some protection against that.

Is it enough difference to tell? Probably not and I cannot tell it. If it made that much of an impact, there would be no covers used on any amp, and every amp would have a fan in it.

Steve

I love you Steve, but your tube theory is off a little.

If it's that simple then why does an RFT sound different than a Sovtek, or a JJ?
What controls the flow of electrons?
What's an electron cloud?
There's nothing magnetic inside a tube.
Electrons flow negative to positive.
What happens inside a tube is magic and most of what's happening can't be seen so many don't understand it.
Jerry

 

[Greazygeo]

They're like tube condoms. Of course the playing feel is going to be more sensitive with them off.

And I thought they were just scared of the dark inside the covers....

You have a bottle with a vacuum inside.
In that vacuum are magnetic/metallic plates.
An electrical charge is introduced on the cathode.
Electrons flow from positive to negative, the anode.
Electrons flowing from the cathode to the anode create current.
Nothing to do with being covered or not.

Having said that, one might argue the point that heat is better dissipated with the covers removed. If the tube is cooling faster, it may discharge current at a more efficient rate. There is no such thing as tube "osmosis" as some people are trying to argue. With flow of electrons, a magnetic field is created. With heat, glass expands a little bit too, making the vacuum volume a little larger, then back to size. This to may bring on some inefficiencies. The fields though, attracts other nasty stuff, like RF, UHF, VHF signals. The an aluminum shield, this offers some protection against that.

Is it enough difference to tell? Probably not and I cannot tell it. If it made that much of an impact, there would be no covers used on any amp, and every amp would have a fan in it.

Steve

Nothing to do with heat......

 

[guitarslinger]

I'm all about mojo-fied tricks that might or might not change the tone of an amp. Just because people haven't quantified it yet, doesn't mean it's not different in some way.

FWIW, I don't really hear much a difference with the tube shields removed. Maybe, I should do more testing. :idk:

 

[Greazygeo]

I'm all about mojo-fied tricks that might or might not change the tone of an amp. Just because people haven't quantified it yet, doesn't mean it's not different in some way.

FWIW, I don't really hear much a difference with the tube shields removed. Maybe, I should do more testing. :idk:

Its pretty noticeable with old Marshalls...med gain anyway. I don't hear it much with higain amps. V30's don't have enough top end to hear it if that's what you are using.

 

[Shark Diver]

How is this topic still alive!

You have crossed into another dimension, you have crossed into "The Gear Page"...

 

[Jimmie]

They're like tube condoms. Of course the playing feel is going to be more sensitive with them off.

And I thought they were just scared of the dark inside the covers....

You have a bottle with a vacuum inside.
In that vacuum are magnetic/metallic plates.
An electrical charge is introduced on the cathode.
Electrons flow from positive to negative, the anode.
Electrons flowing from the cathode to the anode create current.
Nothing to do with being covered or not.

Having said that, one might argue the point that heat is better dissipated with the covers removed. If the tube is cooling faster, it may discharge current at a more efficient rate. There is no such thing as tube "osmosis" as some people are trying to argue. With flow of electrons, a magnetic field is created. With heat, glass expands a little bit too, making the vacuum volume a little larger, then back to size. This to may bring on some inefficiencies. The fields though, attracts other nasty stuff, like RF, UHF, VHF signals. The an aluminum shield, this offers some protection against that.

Is it enough difference to tell? Probably not and I cannot tell it. If it made that much of an impact, there would be no covers used on any amp, and every amp would have a fan in it.

Steve

I love you Steve, but your tube theory is off a little.

If it's that simple then why does an RFT sound different than a Sovtek, or a JJ?
What controls the flow of electrons?
What's an electron cloud?
There's nothing magnetic inside a tube.
Electrons flow negative to positive.
What happens inside a tube is magic and most of what's happening can't be seen so many don't understand it.
Jerry

I don't know much of nothing, (double negative noted) but this thread is starting to sound kinda Dum-ba-lish, but what I think I hear you saying echos my belief in saying I don't believe there were ever two identical tubes made. Once the getter ignites, for better or worse, the Tube is what its going to be until it fatigues and ultimately fails. If you break it down to each electron moving as it attempts to balance out within the potential of a circuit, its hard to imagine the multitudes of variables it encouters along its journey. More to fathom than mere mortals could ever comprehend

 

[steve_k]

They're like tube condoms. Of course the playing feel is going to be more sensitive with them off.

And I thought they were just scared of the dark inside the covers....

You have a bottle with a vacuum inside.
In that vacuum are magnetic/metallic plates.
An electrical charge is introduced on the cathode.
Electrons flow from positive to negative, the anode.
Electrons flowing from the cathode to the anode create current.
Nothing to do with being covered or not.

Having said that, one might argue the point that heat is better dissipated with the covers removed. If the tube is cooling faster, it may discharge current at a more efficient rate. There is no such thing as tube "osmosis" as some people are trying to argue. With flow of electrons, a magnetic field is created. With heat, glass expands a little bit too, making the vacuum volume a little larger, then back to size. This to may bring on some inefficiencies. The fields though, attracts other nasty stuff, like RF, UHF, VHF signals. The an aluminum shield, this offers some protection against that.

Is it enough difference to tell? Probably not and I cannot tell it. If it made that much of an impact, there would be no covers used on any amp, and every amp would have a fan in it.

Steve

I love you Steve, but your tube theory is off a little.

If it's that simple then why does an RFT sound different than a Sovtek, or a JJ?
What controls the flow of electrons?
What's an electron cloud?
There's nothing magnetic inside a tube.
Electrons flow negative to positive.
What happens inside a tube is magic and most of what's happening can't be seen so many don't understand it.
Jerry

Why do they sound different....different structure, different surface area, different material. OK, negative to positive. You got me there.

Steve

 

[kirk]

absolutly not any capacitence difference ,"electron flow" whatever is so minor it cant be heard by the human ear,it is all voodoo ,the sheilds are there to protect the tubes and most importantly....to hold them in so they dont fall out ,..thats it ,if your amp is made so the tubes hang upside down,..leave them on,..if not take'm off ,but if your head is on top of your speakers like everyone elses i would say leave them on so you dont shake your tubes loose

Maybe you don't have sensitive ears... I can hear it with my Marshalls. I do agree that if an amp has tubes upside down, leave the covers on. In my 28 years of playing I have never seen a tube pop loose

i have seen several in the shop,in the past 2 years alone, where the tubes are laying on the bottom and a guy saying"i dont know what happen it just stoped",my ears are sensitive and i tested more models than you'd beleive every amp is different and any difference is so minor its not worth leaving them off,if you need that minor difference in the the amp,...your playing the wrong amp, i've been playing 30+ years and have seen it happen even to my own amp let alone the hundreds of repairs i've done

 

[MississippiMetal]

What happens inside a tube is magic

I'm sure Jerry was being sarcastic here.

Everything inside a guitar amp can be scientifically quantified. It would not bother me in the least if the word "mojo" fell right off the planet. It has no business being used in a serious breath to describe what goes on inside a guitar amplifier, and it often is used as a crutch to explain something the descriptor isn't knowledgeable enough to explain in scientific terms.

A tube guitar amplifier is nothing more than a modulated power supply, and everything inside it operates according to ohm's law.

I've been refraining from chiming in again on this thread because I don't like raining on anyone's parade , but I simply do not believe leaving the covers off your preamp tubes causes a large enough heat dissipation to be audible. I've never once pulled preamp tubes out of an amp that had just been in use and found them to be anything other than mildly warm.

And don't tell me I don't have sensitive enough ears. I'm involved with recording and mixing on a regular basis and both of these activities require very sensitive perception of frequencies, so if it's there, chances are I'll hear it.


Many "reputable" amp people are reputable chiefly by their clientele, clientele who are seldom well-versed in tube amp engineering, so of course the amp person is a "guru". It doesn't mean their information is always correct. The guys I listen to are the guys who are reputed by their peers. People like Randall Aiken, Merlin Blencowe and Steve Conner. Even still, these guys aren't infallible.

 

[Greazygeo]

What happens inside a tube is magic

I'm sure Jerry was being sarcastic here.

Everything inside a guitar amp can be scientifically quantified. It would not bother me in the least if the word "mojo" fell right off the planet. It has no business being used in a serious breath to describe what goes on inside a guitar amplifier, and it often is used as a crutch to explain something the descriptor isn't knowledgeable enough to explain in scientific terms.

A tube guitar amplifier is nothing more than a modulated power supply, and everything inside it operates according to ohm's law.

I've been refraining from chiming in again on this thread because I don't like raining on anyone's parade , but I simply do not believe leaving the covers off your preamp tubes causes a large enough heat dissipation to be audible. I've never once pulled preamp tubes out of an amp that had just been in use and found them to be anything other than mildly warm.

And don't tell me I don't have sensitive enough ears. I'm involved with recording and mixing on a regular basis and both of these activities require very sensitive perception of frequencies, so if it's there, chances are I'll hear it.


Many "reputable" amp people are reputable chiefly by their clientele, clientele who are seldom well-versed in tube amp engineering, so of course the amp person is a "guru". It doesn't mean their information is always correct. The guys I listen to are the guys who are reputed by their peers. People like Randall Aiken, Merlin Blencowe and Steve Conner. Even still, these guys aren't infallible.

Nothing to do with heat.....use an old Marshall and a speaker that has some top end...it's plain as day.

 

[MississippiMetal]

What happens inside a tube is magic

I'm sure Jerry was being sarcastic here.

Everything inside a guitar amp can be scientifically quantified. It would not bother me in the least if the word "mojo" fell right off the planet. It has no business being used in a serious breath to describe what goes on inside a guitar amplifier, and it often is used as a crutch to explain something the descriptor isn't knowledgeable enough to explain in scientific terms.

A tube guitar amplifier is nothing more than a modulated power supply, and everything inside it operates according to ohm's law.

I've been refraining from chiming in again on this thread because I don't like raining on anyone's parade , but I simply do not believe leaving the covers off your preamp tubes causes a large enough heat dissipation to be audible. I've never once pulled preamp tubes out of an amp that had just been in use and found them to be anything other than mildly warm.

And don't tell me I don't have sensitive enough ears. I'm involved with recording and mixing on a regular basis and both of these activities require very sensitive perception of frequencies, so if it's there, chances are I'll hear it.


Many "reputable" amp people are reputable chiefly by their clientele, clientele who are seldom well-versed in tube amp engineering, so of course the amp person is a "guru". It doesn't mean their information is always correct. The guys I listen to are the guys who are reputed by their peers. People like Randall Aiken, Merlin Blencowe and Steve Conner. Even still, these guys aren't infallible.

Nothing to do with heat.....use an old Marshall and a speaker that has some top end...it's plain as day.

Then please explain to me in scientific terms exactly why a difference occurs. Until I see it laid out in an explaination according to ohm's law and not Mojo's law, I'll continue to call bullshit.

 

[JakeAC5253]

I'm new to tubes, but isn't their function based loosely on chaos theory? What you have in a tube is not a closed pathway like a wire, the ions are free to bounce around as they please, and not all of them make it to their destination when they are supposed to. Basically that the signal is not obligated to go where it is intended to go, and simply by it arriving there is an act of chance in and of itself? So then everything wouldn't abide solely according to Ohm's law then according to this fact. It couldn't. Ohm's law does not account for chaos, it assumes that everything is going to go as planned, and as such, calculations using Ohm's law even in a closed circuit are often only approximations due to the chaotic nature of an electrical circuit.

 

[MississippiMetal]

No, vacuum tubes' function are based on the theory of electron flow. Electrons boiled off the cathode move toward the most positively charged space nearby. In a basic diode tube, this would be the anode. Grids are inserted in various different tubes for controlling this flow in some manner relative to how they are referenced in the circuit.

Electronic circuits and electrical circuits are two different things.

As with anything there are no absolutes, but even deviations from an ideal can be mathematically quantified and explained.

 

[stephen sawall]

What happens inside a tube is magic

I'm sure Jerry was being sarcastic here.

No one really understands how or why electricity behaves the way it does at this time. I thought that was what he was referring. We know it follows certain laws .....but no one has yet to really understand it.

Then please explain to me in scientific terms exactly why a difference occurs. Until I see it laid out in an explaination according to ohm's law and not Mojo's law, I'll continue to call bullshit.

If he can explain it or not does not change the fact many of us can hear the difference plain as day. The only tool/measurement needed is ears, I am very aware that all peoples ability to hear is not the same. Many people on music forums have done damage to their hearing.
... not like it is a big difference in sound , but it is there.

 

[glpg80]

No, vacuum tubes' function are based on the theory of electron flow. Electrons boiled off the cathode move toward the most positively charged space nearby. In a basic diode tube, this would be the anode. Grids are inserted in various different tubes for controlling this flow in some manner relative to how they are referenced in the circuit.

Electronic circuits and electrical circuits are two different things.

As with anything there are no absolutes, but even deviations from an ideal can be mathematically quantified and explained.

nothing of that post made any sense.

electron flow has everything to do with how your amplifier works.

here, educate yourself.

https://en.wikipedia.org/wiki/Electron

a vacuum tube is not a diode. there are no simillarities whatsoever. a vaccum tube is not dependent upon only a voltage drop across it, a vacuum tube is dependent upon the bias and voltage drop across the anode resistor, current through the anode resistor as well as the current through the tube and voltage across the tube on each vector of a sin wave. you need to study kirchoffs voltage and current laws in simplifying circuits and also how diodes work. diodes are also irrevelant to impedance loads - another important factor in tubes which have explicit datasheet specifications and guidelines to follow.

electrons do not boil. electrons are knocked off the cathode and flow to the anode through the grid to the anode for cathode bias circuits. you knock off the electrons using AC current and a specified amount of voltage depending on the resistor values chosen for impedance loading the tube output and grid inputs when considering the class A sections of preamp tubes. the factor of the output depends on that stage preceding it as well as the source.

 

[MississippiMetal]

No, vacuum tubes' function are based on the theory of electron flow. Electrons boiled off the cathode move toward the most positively charged space nearby. In a basic diode tube, this would be the anode. Grids are inserted in various different tubes for controlling this flow in some manner relative to how they are referenced in the circuit.

Electronic circuits and electrical circuits are two different things.

As with anything there are no absolutes, but even deviations from an ideal can be mathematically quantified and explained.

nothing of that post made any sense.

electron flow has everything to do with how your amplifier works.

here, educate yourself.

https://en.wikipedia.org/wiki/Electron

a vacuum tube is not a diode. there are no simillarities whatsoever. a vaccum tube is not dependent upon only a voltage drop across it, a vacuum tube is dependent upon the bias and voltage drop across the anode resistor, current through the anode resistor as well as the current through the tube and voltage across the tube on each vector of a sin wave. you need to study kirchoffs voltage and current laws in simplifying circuits and also how diodes work. diodes are also irrevelant to impedance loads - another important factor in tubes which have explicit datasheet specifications and guidelines to follow.

electrons do not boil. electrons are knocked off the cathode and flow to the anode through the grid to the anode for cathode bias circuits. you knock off the electrons using AC current and a specified amount of voltage depending on the resistor values chosen for impedance loading the tube output and grid inputs when considering the class A sections of preamp tubes. the factor of the output depends on that stage preceding it as well as the source.

Oh boy, look who's out to get me tonight.

I never said the electron flow had nothing to do with how the amp works. I honestly have no idea where you gathered that I implied the contrary.

Amazing how I can google "Vacuum Tube Diode" and get a screen full of relevant results, isn't it? It's not like they invented the term "diode" along with the solid state diodes. What do you think a vacuum tube rectifier is?

https://en.wikipedia.org/wiki/Vacuum_tub ... nd_triodes

How is "knocked off" a more accurate description than "boiled off" ? Both could be considered slang, and likely discredited by a tube engineer.

 

[glpg80]

AHHHHH

i missed your comma for some reason after no!

my mistake. i figured you were saying they did not apply to electron flow which is incorrect.

im not out to get anyone. just reading the forum and making replies accordingly.

BTW, vaccum tube rectifier =/= ECC83 or countless other tubes. there is a difference in how each is constructed, which im sure you know.

boiled off implies a hot cathode which is incorrect, cathode is low voltage, anode is high voltage. the heaters heat the cathode so that transmission to the anode is possible, they do not give you your signal alone. there is a difference however negligible you would think it may be. one answer is wrong simply bue to the wording, but i think you get the general idea of how it works with current flow.