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i went to my local music store today to buy some new tubes. i was planning on replacing all of the 12AX7 tubes withs 2, 5751's and 1, 12AT7 so i can have a less gain set up. the guy at the store was telling me that i cant just replace pre-amp tubes like that. he said i need to take the amp to a tech and have him adjust some things on it in order for me to make this change. Is this true? i thought i could just change pre-amp tubes with no adjustments. the amp is a peavey valveking.
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Originally Posted by nick2282 i went to my local music store today to buy some new tubes. i was planning on replacing all of the 12AX7 tubes withs 2, 5751's and 1, 12AT7 so i can have a less gain set up. the guy at the store was telling me that i cant just replace pre-amp tubes like that. he said i need to take the amp to a tech and have him adjust some things on it in order for me to make this change. Is this true? i thought i could just change pre-amp tubes with no adjustments. the amp is a peavey valveking.
It depends on the tube---some have a direct cross reference with no adjustments.For example,in the old tweed amps a 12AY7 was often used in the first stage.This is a lower voltage tube and gives a softer sound.I actually replaced the 12AY7 tubes in my tweeds with a 12AX7 to roughen it up a bit.
A 12AT7 is a driver tube for reverb or the final preamp stage before before the power tubes--they might not sound too good in a crtical tone circuit,as they are usually high gain,but try anything! I've done it and it seemed to work okay in some amps.
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I know for a fact that 12AT7's are directly swappable with 12AX7's. The 12AT7 will lower the gain.
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Originally Posted by refin It depends on the tube---some have a direct cross reference with no adjustments.For example,in the old tweed amps a 12AY7 was often used in the first stage.This is a lower voltage tube and gives a softer sound.I actually replaced the 12AY7 tubes in my tweeds with a 12AX7 to roughen it up a bit.
A 12AT7 is a driver tube for reverb or the final preamp stage before before the power tubes--they might not sound too good in a crtical tone circuit,as they are usually high gain,but try anything! I've done it and it seemed to work okay in some amps. yea... what rainer said is true, but so as not to confuse anyone, the 12AT7 is higher in gain than the 12AY7, but it is certainly not a high-gain tube.
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The guy at the store is incorrect, all of the tubes you mentioned will function fine in place of a 12AX7. EDIT - without any changes to the amp whatsoever.
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the guy at the store is probably thinking of power tube biasing
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Originally Posted by thesteve the guy at the store is probably thinking of power tube biasing
...or, he's the amp tech.
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Originally Posted by Hopeful ...or, he's the amp tech.
That's what I was thinking.
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ha!
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Originally Posted by Hopeful ...or, he's the amp tech. anything for a dollar these days i suppose
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went to a different music store today to buy some new tubes and the owner was telling me i shouldnt change them cuz it could screw up the amp something about how peavey amps are made. so i left called peavey and they said i can put in any other type of tube and it wont hurt my amp. i wonder why so many people think its harmful to change the tubes like this. i ended up just ordering a new set from eurotubes today.
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Probably either they're thinking power tubes, or they're a little misinformed.
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Originally Posted by Rainer. Probably either they're thinking power tubes, or they're a little misinformed.
Or... he's the other amp tech in town (Peavey approved of course).
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You've really gotta find out a lot of stuff for yourself these days, people will try to sell you anything to make an extra buck, even the unneccessaries.
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they werent trying to make any extra money, cuz there is nobody to bias amps right now anyway. the amp tech is backed up for like 2 months. i think they just dont know what there talking about. i was readin that getting my amp biased could help the power tubes break up sooner and improve my tone, depending on how its biased. is this true? my amp is currently a peavey valveking which is biased very cold.