Using a Bias Rite or Bias Master to bias your Herbert/Einste

[duesentrieb]

If you should use one of the tools which reads the cathode current you don't need to pull the fuse !

Install the adaptors between the tube(s) and socket(s), read your current on the tool and adjust the bias with a screwdriver that you stick into the black (!) hole. With a Bias-Tool you don't use either the red hole nor the black hole on the far right side.

Any more questions?


Now to the calculations:

Diezels biasing recommendations are for biasing reading the plate current - with bias tools you are reading the cathode current, which should be 5-10% higher than the plate current recommendations.

So instead of 30mA per tube (for EL34s) its 33mA
For the given range of 60-70mA per pair it is 66-77mA per pair - or 33 to 38.5mA.

Any more questions?

Here's a pic (using the DMM method - not with a bias tool) to show you where to put the screwdriver

 

[guitarobert]

Thanks! Looks like I need to increase my setting. I used a bias rite and set EL34s to 29mA.

 

[diezel&gas]

here's my multimeter (DMM)

how should mine to be set up? 200m on the left?

then using this, will i have to remove one fuse at time like it's written above?
is it dangerous to the amp to be powered on ( during the bias setting ) without the fuse(s)?

thanx

 

[duesentrieb]

Please post a pic of the whole DMM - often you need to use different sockets for Volts/Ohm and Amperes.

You need to set it to 200mA DC.

Instructions see sticky on top of the first page - and since you are getting a new, don't worry about that NOW.

 

[diezel&gas]

yes, i'm charging the batteries of the camera... i need 20 minutes just to take a pic

 

[diezel&gas]

this is a preview from the mobile phone camera

 

[duesentrieb]

Black probe to COM
Red to the right socket (on yours its the same for Volts, Ohm and Amp, just the values are different left/right).

Turn wheel to green right side "200m"

 

[diezel&gas]

ok thanx.

i report what the manual say for DC measurements: ...connect the black test lead to the COM jack; then the red to the VΩmA for measurement to 200mA

for measurement between 200mA and 10A put the red test lead to the 10A jack.

and opposite what i wrote above, and as you correct wrote , i have to turn the knob to the right, not to the left!!

 

[diezel&gas]

so, the pics of my DMM set up simulating the bias test

is it properly adjusted now?

 

[duesentrieb]

Yes. Where's Herbert?

 

[diezel&gas]

lol
still there on the shop i have to receive some answers from the shop before to place my order. and i don't like to wait

talking again about the Bias setting...will i have to remove one fuse at time like it's written above?

is it dangerous for the amp to be powered on ( during the bias setting ) without the fuse(s)?

 

[duesentrieb]

Yes. You'll end up in a nuclear devastation

Don't worry - read the instructions and lets talk once you've got the amp.

 

[diezel&gas]

danke!

i'll stop making questions for this day

tomorrow i hope to receive the infos i need from the shop, so i could finally order it

 

[diezel&gas]

If you should use one of the tools which reads the cathode current you don't need to pull the fuse !

Install the adaptors between the tube(s) and socket(s), read your current on the tool and adjust the bias with a screwdriver that you stick into the black (!) hole. With a Bias-Tool you don't use either the red hole nor the black hole on the far right side.

Any more questions?


Now to the calculations:

Diezels biasing recommendations are for biasing reading the plate current - with bias tools you are reading the cathode current, which should be 5-10% higher than the plate current recommendations.

So instead of 30mA per tube (for EL34s) its 33mA
For the given range of 60-70mA per pair it is 66-77mA per pair - or 33 to 38.5mA.

Any more questions?

Here's a pic (using the DMM method - not with a bias tool) to show you where to put the screwdriver

so doing a bias i 'd have to fix it at 77mA using EL34? not 60mA, right?

 

[diezel&gas]

can i use std probes ( shown on the pics above ) or do i need banana plug connectors to plug into the amp?
thanx

 

[slyvren]

can i use std probes ( shown on the pics above ) or do i need banana plug connectors to plug into the amp?
thanx

You can use standard, just be careful and make sure they're touching good. Keeping them always in contact is the best policy. It helps if you have a friend to hold them while you adjust. I do recommend getting the banana style connectors because they're cheap and help out quite a bit.

 

[slyvren]

If you should use one of the tools which reads the cathode current you don't need to pull the fuse !

Install the adaptors between the tube(s) and socket(s), read your current on the tool and adjust the bias with a screwdriver that you stick into the black (!) hole. With a Bias-Tool you don't use either the red hole nor the black hole on the far right side.

Any more questions?


Now to the calculations:

Diezels biasing recommendations are for biasing reading the plate current - with bias tools you are reading the cathode current, which should be 5-10% higher than the plate current recommendations.

So instead of 30mA per tube (for EL34s) its 33mA
For the given range of 60-70mA per pair it is 66-77mA per pair - or 33 to 38.5mA.

Any more questions?

Here's a pic (using the DMM method - not with a bias tool) to show you where to put the screwdriver

so doing a bias i 'd have to fix it at 77mA using EL34? not 60mA, right?

Bias to 33mA if you're using a bias tool like this :

If you're reading 2 tubes at once with that tool 77mA


If you're reading from the amp's test probe sockets.. (like the very first picture Olaf posted) then 65~mA

 

[diezel&gas]

ok thanx so since i'll bias with no bias rite i have to set the bias as normal ( ie 60mA per pair as as suggested for EL 34s )

i think i'll get those banana clips... i searched them on ebay...they're 100 type :| which one will fit on multimeters probes-cables?

thanx so much again

 

[slyvren]

single banana on both ends.

 

[diezel&gas]

thanx mate!

what about these too? http://www.banzaimusic.com/Connectors/