FENDER EVH 5150 III biasing

[Jeff-tranchina]

My early version had all EH/Sovtek including the preamp tubes.

Current models have JJ's in the power section. Not sure about the 12ax7 pre's though.

If I were to retube today I'd probably go JJ's just cuz thats what they are using but someone here may suggest another brand that they have experience with.

Can't help you with the humming noise... never heard that before. Sorry.

Yeah in their now are JJ's all around. Preamp and power. Didn't know if those were just put in by the last user. I guess ill start by rebiasing it, then if that doesnt solve the humming then ill swap out the tubes. Thanks again.

 

[Buckeyedog]

Whoops.... one more thing. Actually two haha... Does anyone happen to know what stock tubes were in the 5150 iii? I bought it used and I know it takes 6l6 as the power tubes and 12AX7a as the preamp tubes but what brand? And if I put different tubes in do they have to be biased differently? And second, whenever i turn on my amp, without anything plugged in, all the channels make a really noticable like humming noise. It almost sounds like waves or a helicopter on every channel. Could that be from in not being biased properly? Or could the tubes be bad?

This is my first tube amp so sorry for sounding like an idiot hahaha

Sounds like a bad pre amp tube to me. You always need to have a few extra pre amp tube spares around.

 

[Jeff-tranchina]

Whoops.... one more thing. Actually two haha... Does anyone happen to know what stock tubes were in the 5150 iii? I bought it used and I know it takes 6l6 as the power tubes and 12AX7a as the preamp tubes but what brand? And if I put different tubes in do they have to be biased differently? And second, whenever i turn on my amp, without anything plugged in, all the channels make a really noticable like humming noise. It almost sounds like waves or a helicopter on every channel. Could that be from in not being biased properly? Or could the tubes be bad?

This is my first tube amp so sorry for sounding like an idiot hahaha

Sounds like a bad pre amp tube to me. You always need to have a few extra pre amp tube spares around.

Yeah thats what i thought to, but i dont know how to tell if ones bad or not. Also I was told/heard that you shouldnt swap out one tube and should change them all at the same time. How true is that?

 

[Laura]

You unscrew the feet from the bottom plus I think there are a few more screws that have to be removed from the back screen as well. I honestly don't recommend biasing it yourself unless you know what you are doing. There are very dangerous voltages that could kill you.

If you change power tubes, you need to have the bias checked/set. You can swap pre-amp tubes no problem and you don't have to swap them all at once. It sounds like you have a tube problem but my 5153 hummed pretty bad too. I had it serviced and there were multiple cold solder points as well as some other issues that were repaired. Amp sounds awesome now.

As far as what tubes to use...that is all a matter of preference. If you ask 10 guys what to use, likely you will get 10 different answers. I will say that I prefer JJ pre-amp tubes in mine and I tried a number of different tubes when I got the amp. As far as power tubes go, Ruby's or Sovtek WXT+ seem to be a great way to go for not a ton of money. I have SED's in mine right now but I know a few guys who did not like SED's in their 5153.

Hope that helps.

 

[Jeff-tranchina]

You unscrew the feet from the bottom plus I think there are a few more screws that have to be removed from the back screen as well. I honestly don't recommend biasing it yourself unless you know what you are doing. There are very dangerous voltages that could kill you.

If you change power tubes, you need to have the bias checked/set. You can swap pre-amp tubes no problem and you don't have to swap them all at once. It sounds like you have a tube problem but my 5153 hummed pretty bad too. I had it serviced and there were multiple cold solder points as well as some other issues that were repaired. Amp sounds awesome now.

As far as what tubes to use...that is all a matter of preference. If you ask 10 guys what to use, likely you will get 10 different answers. I will say that I prefer JJ pre-amp tubes in mine and I tried a number of different tubes when I got the amp. As far as power tubes go, Ruby's or Sovtek WXT+ seem to be a great way to go for not a ton of money. I have SED's in mine right now but I know a few guys who did not like SED's in their 5153.

Hope that helps.

Yeah I just called up Fender to see whats going on and the guy said it could be a number of things including the tubes. He gave me a tech in my area thats "really good" so i'll give them a call... and yeah after hearing that from a few people i don't plan on biasing it myself haha. But as far as tubes go i think ill stick with the JJ's because i like how the sound aside from the humming haha. I appreciate all the help guys!

 

[Buckeyedog]

Whoops.... one more thing. Actually two haha... Does anyone happen to know what stock tubes were in the 5150 iii? I bought it used and I know it takes 6l6 as the power tubes and 12AX7a as the preamp tubes but what brand? And if I put different tubes in do they have to be biased differently? And second, whenever i turn on my amp, without anything plugged in, all the channels make a really noticable like humming noise. It almost sounds like waves or a helicopter on every channel. Could that be from in not being biased properly? Or could the tubes be bad?

This is my first tube amp so sorry for sounding like an idiot hahaha

Sounds like a bad pre amp tube to me. You always need to have a few extra pre amp tube spares around.

Yeah thats what i thought to, but i dont know how to tell if ones bad or not. Also I was told/heard that you shouldnt swap out one tube and should change them all at the same time. How true is that?

Laura is right on. Just swap one at a time for the pre's with a known good tube. Or you can do the pencil trick where you have your amp on and gently tap on each tube with the eraser and if you hear the ringing or popping sounds, that is likely the bad tube. Good luck.

 

[Jeff-tranchina]

Whoops.... one more thing. Actually two haha... Does anyone happen to know what stock tubes were in the 5150 iii? I bought it used and I know it takes 6l6 as the power tubes and 12AX7a as the preamp tubes but what brand? And if I put different tubes in do they have to be biased differently? And second, whenever i turn on my amp, without anything plugged in, all the channels make a really noticable like humming noise. It almost sounds like waves or a helicopter on every channel. Could that be from in not being biased properly? Or could the tubes be bad?

This is my first tube amp so sorry for sounding like an idiot hahaha

Sounds like a bad pre amp tube to me. You always need to have a few extra pre amp tube spares around.

Yeah thats what i thought to, but i dont know how to tell if ones bad or not. Also I was told/heard that you shouldnt swap out one tube and should change them all at the same time. How true is that?

Laura is right on. Just swap one at a time for the pre's with a known good tube. Or you can do the pencil trick where you have your amp on and gently tap on each tube with the eraser and if you hear the ringing or popping sounds, that is likely the bad tube. Good luck.

Well how can you tell which one is good tube?

 

[Jeff-tranchina]

Whoops.... one more thing. Actually two haha... Does anyone happen to know what stock tubes were in the 5150 iii? I bought it used and I know it takes 6l6 as the power tubes and 12AX7a as the preamp tubes but what brand? And if I put different tubes in do they have to be biased differently? And second, whenever i turn on my amp, without anything plugged in, all the channels make a really noticable like humming noise. It almost sounds like waves or a helicopter on every channel. Could that be from in not being biased properly? Or could the tubes be bad?

This is my first tube amp so sorry for sounding like an idiot hahaha

Sounds like a bad pre amp tube to me. You always need to have a few extra pre amp tube spares around.

Yeah thats what i thought to, but i dont know how to tell if ones bad or not. Also I was told/heard that you shouldnt swap out one tube and should change them all at the same time. How true is that?

Laura is right on. Just swap one at a time for the pre's with a known good tube. Or you can do the pencil trick where you have your amp on and gently tap on each tube with the eraser and if you hear the ringing or popping sounds, that is likely the bad tube. Good luck.

Well how can you tell which one is good tube?

 

[nwright]

It's easier to say which one is the bad tube. When you are swapping tubes and the hum stops, the one you've removed at that swap is the bad one, lol.

FWIW, my 100 watt head came with 4 bad JJ preamp tubes, in mine these 4 were microphonic. When swapping and testing, I ued an old EH12ax7 I had and I noticed that the EH pre tube in the effects loop or phase inverter slot would make the amp hum (I can't remember which back preamp slot it was).

My 50 watt EVH has had no problems with the preamp tubes.

Also, as far as biasing and removing the chassis, you don't have to remove the feet on the bottom of the 100 watt head. Just the screws next to the feet and in the center of the headshell are all you need to remove from there. The bias test points are easy to see as the PCB has them labeled with a + and - and "bias". There is a single blue pot for adjusting the bias, too. Easy peasy. But upping the bias to around 30ma to me sounded too muddy. I liked it where it was set from the factory myself.

 

[Jeff-tranchina]

It's easier to say which one is the bad tube. When you are swapping tubes and the hum stops, the one you've removed at that swap is the bad one, lol.

FWIW, my 100 watt head came with 4 bad JJ preamp tubes, in mine these 4 were microphonic. When swapping and testing, I ued an old EH12ax7 I had and I noticed that the EH pre tube in the effects loop or phase inverter slot would make the amp hum (I can't remember which back preamp slot it was).

My 50 watt EVH has had no problems with the preamp tubes.

Also, as far as biasing and removing the chassis, you don't have to remove the feet on the bottom of the 100 watt head. Just the screws next to the feet and in the center of the headshell are all you need to remove from there. The bias test points are easy to see as the PCB has them labeled with a + and - and "bias". There is a single blue pot for adjusting the bias, too. Easy peasy. But upping the bias to around 30ma to me sounded too muddy. I liked it where it was set from the factory myself.

Alright that makes sense haha. Ill do a little trial and error. Thanks again guys

 

[adrianher]

Hi guys, I'm new in these forum.
I'm from Argentina and 3 years ago I got an EVH 5153 from CHile since here none wanted me to take one from usa.
Now that I want to change the power tubes and adjust them I found out that my amp has a plate voltage of 398VDC, my wall socket voltage is 213VAC (the amp says in the chasis 230VAC since is especification for Europe), and a Heater Voltage of 3,6VAC.
So when I measure cathode current of each tube (using the biasking) I get values from 10 to 20mA in tubes setting the bias trimpot at max posittion sweep.

Can anyone help me to find out what's going on?

Thanks

 

[Oblivion DC]

Hi guys, I'm new in these forum.
I'm from Argentina and 3 years ago I got an EVH 5153 from CHile since here none wanted me to take one from usa.
Now that I want to change the power tubes and adjust them I found out that my amp has a plate voltage of 398VDC, my wall socket voltage is 213VAC (the amp says in the chasis 230VAC since is especification for Europe), and a Heater Voltage of 3,6VAC.
So when I measure cathode current of each tube (using the biasking) I get values from 10 to 20mA in tubes setting the bias trimpot at max posittion sweep.

Can anyone help me to find out what's going on?

Thanks

Sounds like the tubes may not be matched and there should be a resistor you can change to get it into a more useful range.

 

[Oblivion DC]

Hi guys, I'm new in these forum.
I'm from Argentina and 3 years ago I got an EVH 5153 from CHile since here none wanted me to take one from usa.
Now that I want to change the power tubes and adjust them I found out that my amp has a plate voltage of 398VDC, my wall socket voltage is 213VAC (the amp says in the chasis 230VAC since is especification for Europe), and a Heater Voltage of 3,6VAC.
So when I measure cathode current of each tube (using the biasking) I get values from 10 to 20mA in tubes setting the bias trimpot at max posittion sweep.

Can anyone help me to find out what's going on?

Thanks

Sounds like the tubes may not be matched and there should be a resistor you can change to get it into a more useful range.

I've gotta stop posting in bed, I'm falling asleep and resurrecting 3 year old threads!!
:facepalm:

 

[jd267]

You my friend have a really cold grade of tubes . Where did you buy them GC? Lol. Get them from dougs or Laura..