# Bias Meter Suggestions



## traynor_garnet (Feb 22, 2006)

With the talk of switching tubes in my other post, it got me thinking about biasing. After watching a few videos, this seems like something I could do myself if I had the right equipment since my tech already installed a bias pot in my amp.

Does anyone have any recommendations. I don't want cheap junk that is inaccurate and prone to breaking, but I don't need an uber quality commercial unit either. This is just for personal use for the odd time I switch tubes.

The Eurotubes "Pro One" looks interesting but perhaps a multimeter and probe would be enough. It would be nice to know both the plate current and voltage however.

Eurotubes - Bias Probes for vacuum tube valve amps!

TG
 One" Bias Probe


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## J S Moore (Feb 18, 2006)

That looks like just the ticket. I purchased the Bias-rite meter years ago from the Tubestore.


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## nonreverb (Sep 19, 2006)

+1 on the Bias-Rite. I've had a dual socket one for years....and it's survived my abuse with little trouble.



J S Moore said:


> That looks like just the ticket. I purchased the Bias-rite meter years ago from the Tubestore.


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## traynor_garnet (Feb 22, 2006)

J S Moore said:


> That looks like just the ticket. I purchased the Bias-rite meter years ago from the Tubestore.


Actually, if you meant the bias _king, _that is the other one I have been looking at (but it is more money). I have read too many bad things about the Weber bias rite to consider it.


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## GTmaker (Apr 24, 2006)

I got this one and it seems to do all I need it to.

Dual Bias Tester Probe for Vacuum Tube Guitar Amplifier by AMP-HEAD


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## jb welder (Sep 14, 2010)

This is a nice kit, at a decent price: TubeDepot Bias Scout Kit Parts only, you must assemble yourself. Ideally, you would want 2 of them for push-pull amps. 
Also, there is a resistive network to step down the plate voltage for safety reasons. So your meter will show millivolts instead of actual plate volts. So you don't have high voltage waiting to bite you, sitting on a connector which you may or may not be using.

Now if money is no object, you want this: Compu-Bias™ Computerized Tube / Valve Bias Meter It even calculates the wattage for you.


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## surlybastard (Feb 20, 2011)

I have one of the eurotubes $25 bias probes you plug into a multimeter. Has worked fine for me for a number of years.


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## Wild Bill (May 3, 2006)

traynor_garnet said:


> With the talk of switching tubes in my other post, it got me thinking about biasing. After watching a few videos, this seems like something I could do myself if I had the right equipment since my tech already installed a bias pot in my amp.
> 
> Does anyone have any recommendations. I don't want cheap junk that is inaccurate and prone to breaking, but I don't need an uber quality commercial unit either. This is just for personal use for the odd time I switch tubes.
> 
> ...


After all these years, I have never bothered! That's a lot of money for a bit of convenience. Usually I just install 1 ohm, 1/2W cathode test point resistors and measure the voltage drop across them. One bonus with doing this is that if an output tube ever shorts the cathode resistor will blow like a fuse, preventing other damage. Cheap insurance.

When an amp is built such that installing such resistors is just too much a pain in the ass, I simply measure the DC resistance of each side of the OT primary and measure the voltage drop to calculate the idle current. It's a simple matter once the plate voltage and the winding resistance is known to calculate a target voltage drop..

You do have to be a bit careful with leads because you are playing on the high voltage side of things but hey, you should be doing that anyway!

Wild Bill/Busen Amps


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## StevieMac (Mar 4, 2006)

traynor_garnet said:


> I have read too many bad things about the Weber bias rite to consider it.


From what I understand, the only issue with those was related to people who played through their amps while the units were plugged in, causing spikes in voltage that, naturally, overwhelmed the meters. It was a dumb thing to do in the first place and then those same jackasses complained when their meters died. Stupid is as stupid does I suppose.

Anyway, I've used the Weber unit for years _as per the instructions _and it continues to work flawlessly.


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