Tube Manufacturers
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Super Turbo Deluxe Custom
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That's what Max would call an, "Oh yeah!" response.
Superlizard
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Hey, imagine that - two people who disagree. The world's goin' to hell in a handbasket, I tells ya. :doh:
And I don't see any bitch-slapping yet. LOL
And I don't see any bitch-slapping yet. LOL
Jusatele
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simply put guys, if you put a resister in front of a preamp tube cathode circuit, you restrict the voltage and you are biasing the tube, most amp companies do this as a fixed amount, non adjustable
the letter you see on a 12ax7 is telling us about the design of the cathode and the plate, so that is why a WA and a R sound different, so putting 2 WAs and a C will not sound as if you use 3 Rs, plus the cathode voltage of each needs to be different to get responce you want, that is why if you change a WB to a C they sound different.
third, the scale we match tubes on is not mojo, it is a 10 step scale that they tubes are (used to be) marked from the factory, but to make money from us they now sell matched sets and charge up the yang yang on something we could have done ourselves when you could walk into an electronics store and pick them out of a tray of hundreds, and if they were not maeked there was a tester right there you popped them into to test them.
I could go through miles of tech talk about tubes and development since 1904 but that is bottom line, Yes we can Bias a preamp if we want and get different sound from them, but then how do you sell your unique sound of your amp if everyone in the world can change thier's up?
I am sorry it comes to this but if people would ask for a clarification instead of popping off and saying what I said was gibberish.
now power amp tubes we use a different architecture and in that architecture we need to balance a lot of stuff, and when you see what is happening inside a tube, electrons bombarding a plate, and in doing so knocking off spare electrons from that plate it starts to look like a battlefield and you need grids to control both the electrons from the cathode and the spares to keep the thing running how you want it to with out it overheating and melting the grids or plate. So we see why we went to Solid state, Tubes are hard to get to work correctly and we have never done it, that is why we need to replace them when they burn out. and why solid state does not burn out as part of it's natural operation.
most of the good books about this I own are from the 50s and 60s and out of print because we no longer use tube technology, except in a few industries such as Guitar amps, HiFi electronics which are in the higher end of electronics to name a few and development is not very rapid such as in the silicon chip fields.
the letter you see on a 12ax7 is telling us about the design of the cathode and the plate, so that is why a WA and a R sound different, so putting 2 WAs and a C will not sound as if you use 3 Rs, plus the cathode voltage of each needs to be different to get responce you want, that is why if you change a WB to a C they sound different.
third, the scale we match tubes on is not mojo, it is a 10 step scale that they tubes are (used to be) marked from the factory, but to make money from us they now sell matched sets and charge up the yang yang on something we could have done ourselves when you could walk into an electronics store and pick them out of a tray of hundreds, and if they were not maeked there was a tester right there you popped them into to test them.
I could go through miles of tech talk about tubes and development since 1904 but that is bottom line, Yes we can Bias a preamp if we want and get different sound from them, but then how do you sell your unique sound of your amp if everyone in the world can change thier's up?
I am sorry it comes to this but if people would ask for a clarification instead of popping off and saying what I said was gibberish.
now power amp tubes we use a different architecture and in that architecture we need to balance a lot of stuff, and when you see what is happening inside a tube, electrons bombarding a plate, and in doing so knocking off spare electrons from that plate it starts to look like a battlefield and you need grids to control both the electrons from the cathode and the spares to keep the thing running how you want it to with out it overheating and melting the grids or plate. So we see why we went to Solid state, Tubes are hard to get to work correctly and we have never done it, that is why we need to replace them when they burn out. and why solid state does not burn out as part of it's natural operation.
most of the good books about this I own are from the 50s and 60s and out of print because we no longer use tube technology, except in a few industries such as Guitar amps, HiFi electronics which are in the higher end of electronics to name a few and development is not very rapid such as in the silicon chip fields.
DangerousR6
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Superlizard said:
Death by Uberschall
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DangerousR6 said:
I tried two set of Groove Tubes EL34's, both times I had runaway current draw and blew the mains fuse. Went back to the JJ stuff and no problem. The E34L is supposed to have an extended bottom end when compared to the EL34.
DangerousR6
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:icon_biggrin:Death by Uberschall said:
Death by Uberschall
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What you waiting for???DangerousR6 said::icon_biggrin:Death by Uberschall said:
DangerousR6
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In due time.... :laughing7:Death by Uberschall said:
Jusatele
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I use to have a chart I had gotten from a store that had the tubes listed by type and the electrical requirements they required, it was for comparison reasons. I know just because it fits does not mean it is compatible. I know between a 6v6, 6L6 and 5881 there is a 400 Ma difference in draw with close to twice the disapation, so yes you can easily blow fuses without going with the speced tube
Jusatele
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so then you are saying there is no way to bias a 12ax7? no way in the world, correct?
http://archive.ampage.org/threads/0/ampdiy/012706/12AX7_Plate_Resistors-1.html
http://www.shine7.com/audio/12ax7_pre.htm
http://www.tdpri.com/forum/archive/index.php/t-114384.html
http://www.harpamps.com/micKqanda/What-is-Bias.html
http://music-electronics-forum.com/t17008/
http://gabevee.tripod.com/mysecamp.html
there is a huge difference between a fixed bias and not needing to rebias and being able to bias. Yes you can and manufacturers do bias preamps to where they want them
and you can easily change that bias or make it varible
http://archive.ampage.org/threads/0/ampdiy/012706/12AX7_Plate_Resistors-1.html
http://www.shine7.com/audio/12ax7_pre.htm
http://www.tdpri.com/forum/archive/index.php/t-114384.html
http://www.harpamps.com/micKqanda/What-is-Bias.html
http://music-electronics-forum.com/t17008/
http://gabevee.tripod.com/mysecamp.html
there is a huge difference between a fixed bias and not needing to rebias and being able to bias. Yes you can and manufacturers do bias preamps to where they want them
and you can easily change that bias or make it varible
O
OzziePete
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Jusatele said:
I am a completely unqualified person making a naive observation here, so don't jump down my throat. But if the preamps were bias adjustable & if they were adjusted, wouldn't that cause a lot of problems down the line in the signal chain with the various components leading into the power stage and into the actual power stage? I mean: the tolerances that the various components have, after the preamp, may not have the slackness we associate with tubes on adjustable bias circuits (where power tubes can be given a massive tweak if you wanna risk them)? :dontknow:
Jusatele
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Ozzie, preamps do not amplify signal, they (for lack of a better term) shape it, oh they boost it to a level the amp can use, ut they do not amplify it. Yes when you adjust something other things happen, and is the argument to not have adjustments to the bias of a preamp tube, so that the manufacturer can sell a product that has a dependable output. You can see in different manufacturers that the way they approach preamp design which includes preamp cathode voltages) gives them the distinctive sound they sell.
http://www.ehow.com/about_5041020_preamplifier.html
http://www.ehow.com/about_5041020_preamplifier.html
O
OzziePete
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Jusatele said:
OK thanx for clarifying that, but if the next lot of components introduced in the circuit from the preamp tubes are only meant to see 'xx' Voltage and instead you adjust that to read higher, isn't there a fear that the components will fail or at least perform less than favourable due to being under duress? Bias, in this preamp stage, still refers to the voltages, right? A manufacturer is aware that people will adjust the power tube bias, but I bet they don't account for preamp bias adjustment and would probably get very close in their tolerances in that stage under the assumption that no-one would seek to change that... :icon_scratch:
(I must say I have never heard of preamp bias or it's adjustment)
Patrick from Davis
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Out of curiosity, what is the difference between boosting a signal and amplifying one?
DbU and Doug, I am curious if either of you has ever tried the KT77 as a replacement for the EL34. They do sound a bit tighter to me. More Metal less Classic Rock. Still, I'd like to hear your reviews if you have tried them.
Patrick
DbU and Doug, I am curious if either of you has ever tried the KT77 as a replacement for the EL34. They do sound a bit tighter to me. More Metal less Classic Rock. Still, I'd like to hear your reviews if you have tried them.
Patrick
Jusatele
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http://books.google.com/books?id=ByJG1iwUHBAC&pg=PA18&lpg=PA18&dq=measuring+signal+strength+in+dbm+electric+guitar&source=bl&ots=PkoAzEzyIx&sig=Tg-1o6e3FNJLMfrbAK60WT5wq8g&hl=en&ei=JoptTaSmDIbksQPVjoitBQ&sa=X&oi=book_result&ct=result&resnum=3&sqi=2&ved=0CCMQ6AEwAg#v=onepage&q=measuring%20signal%20strength%20in%20dbm%20electric%20guitar&f=false
Patrick from Davis
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Thanks for the link, but it doesn't really help. CB's comments were correct. The preamp tubes are operating in Class A manner, and are cathode biased. While you can mess with the level of the resistance in that manner of biasing, in general the preamp circuitry is designed to keep the tubes in an optimum performance range. CB's post was a nice description of how the cathode biasing works. He said quite clearly that most are set at 1.8 mA. To say a pre amp doesn't amplify is kind of funny, when amplifier is part of the name. Just an observation.
I guess one of the things I enjoy is that CB writes a nice explanation out when information is required, and he can help. I find linking to a page less helpful when concepts are being discussed. It seems rather impersonal, when a couple of sentences would do the job.
Patrick
I guess one of the things I enjoy is that CB writes a nice explanation out when information is required, and he can help. I find linking to a page less helpful when concepts are being discussed. It seems rather impersonal, when a couple of sentences would do the job.
Patrick
