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Which bias tool should I get?


rog951

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I was about to buy a Weber Bias Rite and I got to wondering if I might've missed a better tool, or a similar tool for less $$$. Then I thought, who better to ask than all the guys here at HCAF?! ;) So, what tools are you guys using to bias your amps and do you like/dislike them? How much didja pay, and all that jazz...

 

Thanks! :wave:

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Thanks guys! I came to the same conclusion but I figured it couldn't hurt to ask. Hey, what's the deal with the 4-head version? I thought you only needed to open a tube pair to measure the current, hence you'd only need max two heads for a 100W amp...unless your amp has more than two pairs of power tubes??? Am I missing something? :confused:

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Originally posted by sekler

beside going the regular multimeter way, I haven'T heard about anything else that is better for the price than the Weber Bias Rite on webervst.com

 

 

Thanks! Do you know anything about the 4-head version? Why would I need that?

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Originally posted by adiohead

i have a 4 head version.


it's cool because you get to check the draw on all the tubes at once.


but you're right. you'd only really need a 2 head version.



tubes.jpg


just make sure you get the VI option like Code-001 said

 

Cool! Thanks for the info. I guess there is some value in seeing the current from each tube, just so you know, but there's really no way to indiviually adjust it on most amps, right? I was eyeing up the four head with 2 9-pin and 2 octal heads actually, seems like that'd cover you for almost anything! :thu:

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Originally posted by Extasyguy

So, does the Bias Rite eliminate any need for an oscilloscope?

I spoke to a tech who said that you need to use one when using a multimeter.

 

 

 

i think that's only when you're trying to find problems with noise?

not sure though

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You should check the bias on every tube to make sure they're all operating as they should. Sometimes they may drift away from each other, you'll get a bad one etc etc. The 4 heads just lets you check them all easily. You can actually get away with just one, but you have to shut the amp off and move it to each tube one at a time. Having more heads just saves you that hassle.

You don't need an o-scope. It's another method of biasing that some prefer but it isn't absolutely necessary.

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Originally posted by Extasyguy

So, does the Bias Rite eliminate any need for an oscilloscope?

I spoke to a tech who said that you need to use one when using a multimeter.

 

 

The real point of biasing the amp is to remove any odd-order harmonics from the power stack in the amp. The only real way to do this is to actually put a scope on the amp so you can see the signal structure.

 

Biasing via a meter will do the job fairly well, and certianly good enough so you won't actually hurt the amp by running it, however, by simply using a meter it is impossible to tell what the signal actually looks like.

 

You may have heard stories of that really sweet amp, that sounds better then all the others made at the same time by the same manufacture. Often, this amp turns out to be one that has mismatched power tubes that were biased via a scope to remove the harsh harmonics mismatching causes. If you use a scope, you don't have to have matched power tubes, because you can tweak around the mismatch. If you use a meter, you pretty much need matched tubes.

 

Scope is always better, but a meter will get the job done. If you don't know what you're looking at when you're using a scope, then there is no sense is buying one anyway.

 

-W

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Originally posted by starsnuffer



The real point of biasing the amp is to remove any odd-order harmonics from the power stack in the amp. The only real way to do this is to actually put a scope on the amp so you can see the signal structure.


Biasing via a meter will do the job fairly well, and certianly good enough so you won't actually hurt the amp by running it, however, by simply using a meter it is impossible to tell what the signal actually looks like.


You may have heard stories of that really sweet amp, that sounds better then all the others made at the same time by the same manufacture. Often, this amp turns out to be one that has mismatched power tubes that were biased via a scope to remove the harsh harmonics mismatching causes. If you use a scope, you don't have to have matched power tubes, because you can tweak around the mismatch. If you use a meter, you pretty much need matched tubes.


Scope is always better, but a meter will get the job done. If you don't know what you're looking at when you're using a scope, then there is no sense is buying one anyway.


-W

 

 

Thanks:thu:

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Originally posted by Extasyguy

So, does the Bias Rite eliminate any need for an oscilloscope?

I spoke to a tech who said that you need to use one when using a multimeter.

 

 

Steve Fryette from VHT said that this was more of an approximate tool, as to have the most accurate and precise readings, tools like oscilloscope and stuff like that would be the best..but it's pretty much out of reach of most people as they are probably not that much affordable I guess and complicated ?

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Originally posted by starsnuffer



The real point of biasing the amp is to remove any odd-order harmonics from the power stack in the amp. The only real way to do this is to actually put a scope on the amp so you can see the signal structure.


Biasing via a meter will do the job fairly well, and certianly good enough so you won't actually hurt the amp by running it, however, by simply using a meter it is impossible to tell what the signal actually looks like.


You may have heard stories of that really sweet amp, that sounds better then all the others made at the same time by the same manufacture. Often, this amp turns out to be one that has mismatched power tubes that were biased via a scope to remove the harsh harmonics mismatching causes. If you use a scope, you don't have to have matched power tubes, because you can tweak around the mismatch. If you use a meter, you pretty much need matched tubes.


Scope is always better, but a meter will get the job done. If you don't know what you're looking at when you're using a scope, then there is no sense is buying one anyway.


-W

 

Are you saying that by twiddling that one little pot, varying a DC bias voltage that is the same where it terminates at each tube, you can dial out all the odd-order harmonics from the amp's output?!?! Unless your amp has a pot on each tube's bias supply? Pretty sure none of mine do. I'm not really understanding how this works.

 

I do have an O-scope at home...and it's so old it's tube powered! :D I wonder how to bias the tubes in that scope! ;)

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