BIAS probes (Weber BiasRite, TAD BiasMaster, Compu-Bias etc)

  • Thread starter Thread starter VH4paul
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VH4paul

VH4paul

Member
Hi guys,
we started talking about this stuff in another bias-related thread, but I thought it would have been useful to open a new one as a point of reference for all the users.

Well, I'm looking for a good bias probe for my VH4 and this is what I found (please consider I used the 4-probes version where available as suggested by Papa Peter himself):


Weber Bias Rite BR-4 (octal) ** DISCONTINUED **

PRICE: $135 + shipment
PLATE VOLTAGE READING: yes
TUBE DISSIPATION READING: no
PROBES: 4
TUBES SHOWN/TESTED AT THE SAME TIME: 1
REPLACEMENTS: $25 a head + return shipping (the unit needs to be sent back to factory to be fixed)
Made in USA


TAD Bias Master BM4

PRICE: €149,80 + shipment
PLATE VOLTAGE READING: no
TUBE DISSIPATION READING: no
PROBES: 4
TUBES SHOWN/TESTED AT THE SAME TIME: 1
REPLACEMENTS: €49,00 + shipment for a pair of octal spare probes (BMA2)
Made in Germany


Ruby Bias Tester

PRICE: €135,00 + shipment
PLATE VOLTAGE READING: no
TUBE DISSIPATION READING: no
PROBES: 2
TUBES SHOWN/TESTED AT THE SAME TIME: 1
REPLACEMENTS: €35,00 + shipment for a pair of octal spare probes (EQBMP)
Made in China


Compu-Bias

PRICE: $219.99 + shipment
PLATE VOLTAGE READING: yes
TUBE DISSIPATION READING: yes
PROBES: 2
TUBES SHOWN/TESTED AT THE SAME TIME: 2
REPLACEMENTS: $29.99 + shipment for a single octal probe
Made in USA


Bias King / Bias King PRO

PRICE: $159.99 / $259.99 + shipment
PLATE VOLTAGE READING: no
TUBE DISSIPATION READING: no
PROBES: 1 / 2
TUBES SHOWN/TESTED AT THE SAME TIME: 1
Made in USA


Wombat (by Aiken Amplification)

PRICE: $150 (control unit only) + $35 (dual octal probe) + shipment
PLATE VOLTAGE READING: yes
TUBE DISSIPATION READING: yes
PROBES: 2 or 4
TUBES SHOWN/TESTED AT THE SAME TIME: 2 (with one Dual octal probe) or 4 (with two Dual octal probes); the unit automatically recognizes how many probes are connected.
REPLACEMENTS: $35 + shipment for a dual octal probe
Made in USA


Other features can be found on the product pages.

What's your favourite one? Please share your experience and suggestions, it may help a lotta folks out there (me included :D ).

Thanks :thumbsup:
 
duesentrieb":s7ygnzvl said:
http://www.tube-town.net/ttstore/product_info.php/language/en/info/p3132_Bias-Messadapter-Oktal--Fertigadapter.html

25 Euro - add 10 Euros for a DMM from your local hobby shop.
Click to expand...
Thanks man, this one seems like a good cheaper option but I guess you can test one tube at a time (with a matched quartet it shouldn't be a problem, but you never know :D ), am I right?
Besides, since I'm barely able to recognize a multimeter from a calculator (lol :D ), how should I use this probe?
Below there a picture of my DMM:


dmmf.jpg



Thanks a lot! :thumbsup:
 
slyvren":1r0xm7zc said:
VH4paul":1r0xm7zc said:
duesentrieb":1r0xm7zc said:
200mV - 90° west :D
Click to expand...
thanks Captain!!! :D

What about the red and black plugs? :confused:
Click to expand...

Black = com
Red = the one above it with the mV at the end.
Click to expand...

Thanks! ;)

What about the other probes? Have anyone had experience with them?
 
I have TAD Bias Master with four probes. Extremely expensive as there is nothing fancy, but it is easy and fast to use. If you know how to proceed with e.g. multimeter I don't see much reason why to purchase any of these unless you have additional cash and are biasing rather often. My personal opinion is that it is good product that has its place on market (as well as the Weber's product, etc.), but people do have issues with accepting the set price-level. Speciality product in niche market often leads into speciality price.

The main advantage I consider that these bias masters, rites, etc. have is that they have the possibility to measure each tube separately, but still in a way "simultaneously" without turning the amp off and changing the probe to other tube. I would also argue that to certain level it may be said that these products are safer to use. Also, sometimes I have been a bit surprised about the matched quartet of tubes not being that well matched and those are the cases when the 4 "simultaneus" probes are handy.

This might be a stupid question, but could someone clarify me that why someone wants to read the plate voltage each time you set the bias for your amp's tubes? Ain't that fixed and if everything is OK it should remain that way? I think that usually this information can be found from manual or by asking from the manufacturer (esp. with modern amps). Maybe with older amps this could be more useful, but I think it is nothing that you are not able to do with good quality multimeter.


P.S. Sorry VH4paul, I forgot to reply to you on the other thread concerning the same topic
 
Plate voltage is constant - as long as your input voltage is constant (with in range of course like 225-235V).

If your input voltage isn't constant all supplies will have a degree of variation (plate, bias, heaters).
 
duesentrieb":2nc70wod said:
Plate voltage is constant - as long as your input voltage is constant (with in range of course like 225-235V).

If your input voltage isn't constant all supplies will have a degree of variation (plate, bias, heaters).
Click to expand...


Thank you duesentrieb. This is what I have understood as well. So basically there is no reason to check the plate voltage when I bias my amps if I know what the plate voltage should be. In other words we can make an assumption that unless you are working with amps which plate voltage you do not know, the feature of reading the plate voltage like in i.e. Weber Bias Rite is more or less useless?
 
You just need to read it once for each amp. If you should have several amps though . . .
 
Get the Bias Rite. The local amp techs around here want to take 2 weeks and charge an insane amount to install and bias new tubes. I have used mine 3 times since I bought it several years ago and it paid for itself after the 2nd use. I am very ignorant to electrical work, but even I can use the Bias rite.
 
smdb":32gizzl6 said:
Get the Bias Rite. The local amp techs around here want to take 2 weeks and charge an insane amount to install and bias new tubes. I have used mine 3 times since I bought it several years ago and it paid for itself after the 2nd use. I am very ignorant to electrical work, but even I can use the Bias rite.
Click to expand...
Same here...hard to find someone who really knows what he's doing, plus long waitings and money to waste in such a basic thing.

i.ak":32gizzl6 said:
duesentrieb":32gizzl6 said:
Plate voltage is constant - as long as your input voltage is constant (with in range of course like 225-235V).

If your input voltage isn't constant all supplies will have a degree of variation (plate, bias, heaters).
Click to expand...


Thank you duesentrieb. This is what I have understood as well. So basically there is no reason to check the plate voltage when I bias my amps if I know what the plate voltage should be. In other words we can make an assumption that unless you are working with amps which plate voltage you do not know, the feature of reading the plate voltage like in i.e. Weber Bias Rite is more or less useless?
Click to expand...
I was wondering about this too. Maybe in this case that feature is not so useful; with Diezels we pretty much know the plate voltage (for VH4 450v to 480v depending on the age of the amp, right?) and above all there are official suggestions about biasing a certain tube (ex. 60mA per pair of EL34).

So my question is: do I really need to know the exact plate voltage of my amp even if I follow the official instructions? My VH4 is a 2010 model, is it possible to know what's its plate voltage based on this?
 
I've hovered around this thread for a while, I just wanted to say I bought a Weber Bias Rite with 4 leads for future biasing. Haven't used it yet, but I was a bit 'tentative' with the croco shunt method and the voltages/amperages in hand - literally. I wanted the WBR in order to simply jam them in the sockets with their respective tubes, dial it in (regardless of it being upside down) and be able to see "all four" tubes' status at the same time.

Just in response to the OP.

Peace,
V.
 
Ventura":2smbqry0 said:
I've hovered around this thread for a while, I just wanted to say I bought a Weber Bias Rite with 4 leads for future biasing. Haven't used it yet, but I was a bit 'tentative' with the croco shunt method and the voltages/amperages in hand - literally. I wanted the WBR in order to simply jam them in the sockets with their respective tubes, dial it in (regardless of it being upside down) and be able to see "all four" tubes' status at the same time.

Just in response to the OP.

Peace,
V.
Click to expand...
Thanks Ventura, this is one of the reasons I'd like to get one with 4 probes.

duesentrieb":2smbqry0 said:
Peter can tell from the serial number of course.
Click to expand...
done...thanks for the suggestion ;)
 
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