Bias VTL IT-85 doubt - help needed

[Miracle1980]

Hello guys,

I bought and installed a matched quartet of 6CA7-Z black Treasure for my integrated amplifier VTL IT-85.
They seem to sound really good but I wait for burn-in before final judgement.

I have a question/doubt about the Bias that I already did:

On the valves box I see there is written "Ia 25mA" (initial current?)

My integrated amplifier (VTL IT-85) has resistance of 10ohm and the bias suggested range is 275mV - 300mV

Can I leave these valves set it up at 275mV safely?
Or should I set it to 250mV (25mA x 10ohm)?

Below the full specs of these valves:

http://shuguangtube.com/Shuguang-Treasure-Vacuum-Tubes-6CA7-Z-new-matched-pair-p30.html

Thanks

[shooter]

Ia = ANODE (PLATE) current
how many tubes share the 10ohm, 1 for each tube = 27.5mA
to answer what's acceptable you need plate VDC, then multiply that by .0275A and you have dissipated power for each tube at idle.

[Miracle1980]

Ia = ANODE (PLATE) current
how many tubes share the 10ohm, 1 for each tube = 27.5mA
to answer what's acceptable you need plate VDC, then multiply that by .0275A and you have dissipated power for each tube at idle.

As you can see I don't have much knowledge in electricity... :)

The VDC of the integrated should be around 460 VDC (Push-pull) that multiplied by .0275 is equal to 12.65

Is this a normal/good for these 6CA7-Z? Or do you suggest going lower with mV during Bias?

Thanks

[Latole]

Beware, IMO you may do big mistake

275 mv = 0.275 not 0.0275

460 X 0.275 = 126 watts !!!!

[Latole]

Hello guys,

 On the valves box I see there is written "Ia 25mA" (initial current?)
 
Thanks

This is the bias reading on hid matching instrument when dealer matched all four tubes. It is not useful for you.

[sluckey]

Beware, IMO you may do big mistake

275 mv = 0.275 not 0.0275

460 X 0.275 = 126 watts !!!!

Not so. His bias sense resistor is 10Ω, not 1Ω. Therefore 275mV represents 27.5mA.

[Latole]

Beware, IMO you may do big mistake

275 mv = 0.275 not 0.0275

460 X 0.275 = 126 watts !!!!

Not so. His bias sense resistor is 10Ω, not 1Ω. Therefore 275mV represents 27.5mA.

Right, I did not understand the use of 10 ohms, I am not an English speaker

[Miracle1980]

Hello guys,

 On the valves box I see there is written "Ia 25mA" (initial current?)
 
Thanks

This is the bias reading on hid matching instrument when dealer matched all four tubes. It is not useful for you.

Thank you. So can I stick with 275mv or would you recommend something lower...for example 265mv?

[pdf64]

My reading of the OP is that the manufacturer has provided a target range of 275-300mV for the bias check measurement? If so, why query that?

[Miracle1980]

My reading of the OP is that the manufacturer has provided a target range of 275-300mV for the bias check measurement? If so, why query that?

Actually you are right. I got confused by the 25mA (matched voltage by dealer) written on the valves box. I think the "non problem" is solved  :)