Cathode Bias and Fixed Bias
- Thread starter Pink Unicorn Horsey
- Start date
bancika
New member
Re: Cathode Bias and Fixed Bias
I already said what would be a better and non-monopolistic way - put a pot inside and set it the way mesa tubes require it to be. If you want to stick with mesa tubes you'll never have to change it...if you want to try something else you'd have to change it anyways.
By the way, what's so hard about biasing? It takes 5 minutes and you only need to turn the pot until current is right. I don't see the problem
I already said what would be a better and non-monopolistic way - put a pot inside and set it the way mesa tubes require it to be. If you want to stick with mesa tubes you'll never have to change it...if you want to try something else you'd have to change it anyways.
By the way, what's so hard about biasing? It takes 5 minutes and you only need to turn the pot until current is right. I don't see the problem
StillLearnin'
New member
Re: Cathode Bias and Fixed Bias
I'm biased out :barf:
I'm biased out :barf:
Robert S.
Super Moderator
Re: Cathode Bias and Fixed Bias
You don't have to run Mesa tubes in Mesa amps, only tubes that operate in the same range as Mesa tubes. I put JJs in my 2:90 and all I did was request tubes that were in the proper range for my amp.
Most tube marketing/selling businesses honor that request and it doesn't cost any extra.
You don't have to run Mesa tubes in Mesa amps, only tubes that operate in the same range as Mesa tubes. I put JJs in my 2:90 and all I did was request tubes that were in the proper range for my amp.
Most tube marketing/selling businesses honor that request and it doesn't cost any extra.
ratherdashing
Kablamminator
Re: Cathode Bias and Fixed Bias
You're still confusing "monopoly" with "proprietary".
It's not a problem if you are ok with opening up your amp, finding a trim pot, and reading the current/voltage with a multimeter while the amp is plugged in and powered up. You or I might be comfortable doing that, but we account for about 1% (if that) of the guitar playing population. Everyone else has to take their amp to a tech. That's what Mesa's non-adjustable bias is meant to avoid.
You also missed the part about bias pots drifting out of alignment due to vibration etc., which is the reason R.S. stated for not using them.
Like I said, it's not a perfect solution, but it does mean you'll never have to bias your amp, which for some people is a really good thing. Not many guitarists are going to care what tubes their amp is running. Every guitarist is going to care that their amp works and sounds good every time they power it up. It may seem foolish to you, but you're not a typical guitarist.
You're still confusing "monopoly" with "proprietary".
It's not a problem if you are ok with opening up your amp, finding a trim pot, and reading the current/voltage with a multimeter while the amp is plugged in and powered up. You or I might be comfortable doing that, but we account for about 1% (if that) of the guitar playing population. Everyone else has to take their amp to a tech. That's what Mesa's non-adjustable bias is meant to avoid.
You also missed the part about bias pots drifting out of alignment due to vibration etc., which is the reason R.S. stated for not using them.
Like I said, it's not a perfect solution, but it does mean you'll never have to bias your amp, which for some people is a really good thing. Not many guitarists are going to care what tubes their amp is running. Every guitarist is going to care that their amp works and sounds good every time they power it up. It may seem foolish to you, but you're not a typical guitarist.
ratherdashing
Kablamminator
Re: Cathode Bias and Fixed Bias
Yup, exactly correct. Eurotubes, for instance, will sell you sets of tubes for Mesa amps that are within Mesa tolerances.
Yup, exactly correct. Eurotubes, for instance, will sell you sets of tubes for Mesa amps that are within Mesa tolerances.
bancika
New member
Re: Cathode Bias and Fixed Bias
this isn't going anywhere
Don't get me wrong, I love mesa amps and I'd like to own one (once I can afford it), but R.S is just not my favorite guy in amp making business.
To spice up the original theme of this post: another interesting bias method is with zener diodes, it sounds closer to fixed bias but cool thing about it is that you can mix it with regular cathode bias resistor to get anywhere between cathode bias compression and fixed bias tightness...
Another thing one can do is to bypass cathode bias resistor with a very large capacitor (like 2000uF), that should make the sound more tight and still not have to worry about biasing.
Cheers
this isn't going anywhere
Don't get me wrong, I love mesa amps and I'd like to own one (once I can afford it), but R.S is just not my favorite guy in amp making business.
To spice up the original theme of this post: another interesting bias method is with zener diodes, it sounds closer to fixed bias but cool thing about it is that you can mix it with regular cathode bias resistor to get anywhere between cathode bias compression and fixed bias tightness...
Another thing one can do is to bypass cathode bias resistor with a very large capacitor (like 2000uF), that should make the sound more tight and still not have to worry about biasing.
Cheers
Pink Unicorn Horsey
Megä Pöny Rÿdr
Re: Cathode Bias and Fixed Bias
So from a purely tonal standpoint, is one type of biasing generally considered more desirable than another?
- Keith
So from a purely tonal standpoint, is one type of biasing generally considered more desirable than another?
- Keith
ratherdashing
Kablamminator
Re: Cathode Bias and Fixed Bias
Gee, really? I had no idea.
this isn't going anywhere
Don't get me wrong, I love mesa amps and I'd like to own one (once I can afford it), but R.S is just not my favorite guy in amp making business.
Gee, really? I had no idea.
Pink Unicorn Horsey
Megä Pöny Rÿdr
Re: Cathode Bias and Fixed Bias
Good to know! I generally prefer the compressed and spongy vintage tones. Of course, I don't really do that with my Mesa, but I typically use that amp for modern stuff anyway.
- Keith
Good to know! I generally prefer the compressed and spongy vintage tones. Of course, I don't really do that with my Mesa, but I typically use that amp for modern stuff anyway.
- Keith
Re: Cathode Bias and Fixed Bias
"Since vacuum tubes are "normally on" devices, a trick can be used to bias them without having to supply a negative DC voltage source to the grid. If a resistor is placed between the cathode and ground, and the grid of the tube is referenced to ground (usually by connecting a large value resistor, such as a 1Meg, from grid to ground), the tube will try to conduct a large current from cathode to plate, since the grid and cathode are initially at ground potential. However, this cathode current flow will cause a voltage drop across the cathode resistor, making the cathode voltage positive with respect to the grid."
Not true. The reason cathode biasing works is because the cathode becomes somewhat positive in relation to the anode (plate). The grid then varies in potential regulating the flow of electrons from the cathode to the plate as is normal tube behavior.
"Since vacuum tubes are "normally on" devices, a trick can be used to bias them without having to supply a negative DC voltage source to the grid. If a resistor is placed between the cathode and ground, and the grid of the tube is referenced to ground (usually by connecting a large value resistor, such as a 1Meg, from grid to ground), the tube will try to conduct a large current from cathode to plate, since the grid and cathode are initially at ground potential. However, this cathode current flow will cause a voltage drop across the cathode resistor, making the cathode voltage positive with respect to the grid."
Not true. The reason cathode biasing works is because the cathode becomes somewhat positive in relation to the anode (plate). The grid then varies in potential regulating the flow of electrons from the cathode to the plate as is normal tube behavior.
GoldenVulture
Braindeadologist
Re: Cathode Bias and Fixed Bias
Er , you just posted to a thread that is 8 years dead.
Er , you just posted to a thread that is 8 years dead.
James Rock
Active member
Re: Cathode Bias and Fixed Bias
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I didn't check the dates reading that and though I'd read it before.... And yup I read it 8 years ago...
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