ENGINEERED FOR EVERYONE

THE BLACK ICE EXACT BIASING SYSTEM

Bias settings are below.

When customers hear us say that you’ll have to bias your amplifier under certain circumstances, there can be a moment of panic. However, on our amplifiers, biasing is a simple matter of using the Exact Biasing system and the included Wand.

It’s as simple as turning a potentiometer screw clockwise or counterclockwise and setting it to the right number that is shown in the meter. The needle moves slowly and exactly as you are turning it, so there is no guessing, when it shows the correct number stop turning, if you overshoot turn it back. It’s that easy!

Biasing is used to make sure the tubes are electrically operating in a similar manner, i.e. that all the tubes are pushing out approximately the same amount of electrical power. This allows maximum tube life and is far superior to any auto-bias system on the market, not just the "Cathode Bias" based solutions.

BIAS SETTINGS FOR FUSION AMPLIFIERS

IMPORTANT: Please always push tubes straight down to install them and pull straight up to remove them. Rocking them will cause the pin sockets to spread and result in poor contact. It can be easily fixed but it’s best to avoid by installing and removing your tubes correctly.

Fusion F11:

  • The meter reading for EL84/7189 is 30 milliamps plus or minus +/- 5 milliamps.

Fusion F22/F35/F100s/F65A/F85A/F165Ms:

  • The meter reading for EL34/6CA7/KT77 is 50 milliamps plus or minus +/- 5 milliamps.

  • The meter reading for 6550/KT88/KT90/KT120 tubes is 60 milliamps plus or minus +/- 5 milliamps.

  • The meter reading for KT150/KT170 tubes is 70 milliamps plus or minus +/- 5 milliamps. SEE SPECIAL INSTRUCTIONS BELOW

  • If the reading falls within those parameters, adjusting the bias is not necessary.

  • Please note, that if you are reading the meter while music is playing, the reading will fluctuate.

IMPORTANT: Your amplifier should be running for at least 45 min before you make any adjustments for the EL84/7189/EL34/6CA7/KT77/6550/KT88/KT90/KT120. For the KT150/KT170 your amplifier should be running for at least 2 hours to confirm they are at full operating temperature before any adjustments are made.

HOW TO ADJUST BIAS SETTINGS FOR FUSION AMPLIFIERS USING THE EXACT BIAS SYSTEM.

IMPORTANT: Please always push tubes straight down to install them and pull straight up to remove them. Rocking them will cause the pin sockets to spread and result in poor contact. It can be easily fixed but it’s best to avoid by installing and removing your tubes correctly.

First thing is to Breathe this is really easy and very hard to mess up. Once you do it once you will be able to do it without looking at this page ever again.

A quick and easy method to bias the amplifier is to make certain the tube is at the right bias point or to re-bias. Just use the included Tuning Wand to make it easy!

Important: If changing tube type see tube rolling below.

1. To start the process, turn the unit on with the volume knob turned to 0 (zero). No audio source should be playing.

2. It is important to allow the unit to warm up for at least 20 (twenty) minutes if it’s the first time setting bias.

3. To check your bias, simply turn the bias selector switch to V1, V2, V3 or V4.

4. Bias the V1 tube, first set the Bias Selector switch to V1. Then take the tuning wand, and with the cupped end,

insert it into the V1 hole and turn it until the needle points to the correct number in the meter.

Increase the milliamps by turning the screw Clockwise.

Decrease the reading by turning the screw Counter-Clockwise.

Follow the same pattern to bias the V2, V3, and V4 tubes.

Please Note: if the meter reading fluctuates while music is playing, this is normal.

5. Re-Bias the tubes again after the initial first bias pass. Repeat the steps above.

The reason is that all the tubes use the same power supply voltage. When one tube is moved it affects the others. Increasing amperage to one tube will reduce the amperage from the other three tubes. In like manner, decreasing the amperage from one tube will increase the amperage to the other three tubes. We want to go back a second time and make sure and fine-tune our balance.

6. Leave your amp on for about 2 (two) hours to stabilize the tubes. Recheck the bias and adjust to the optimum setting.

Recheck the bias once a month after the amplifier is at its full operating temperature and adjust as necessary.

  • Full operating temp is about 45 min (forty-five) for EL84/7189/EL34/6CA7/KT77/6550/KT88/KT90/KT120.

  • About 2 hours (120 min) for the KT150/KT170.

Note: The most common errors in biasing the Black Ice Audio amplifier are:

  1. Turning the bias screws the wrong way.

  2. Attempting to "tweak" the bias levels by ear without using the meter on the amplifier which reduces optimum performance.

  3. Please note, that if you are reading the meter while music is playing, the reading will fluctuate.

At Black Ice Audio are always tinkering and want to make a change to our recommended Bias setting for the 6550/KT88s. We now recommend running them at 60 milliamps instead of 50 milliamps. We have found that the extra power opens them up more and can actually extend tube life.

HOW TO BIAS THE EL84/7189/EL34/6CA7/KT77/6550/KT88/KT90/KT120 POWER TUBES

Tubes take some time to settle. Please follow this guide to make sure they have a long life. 

  1. When you get your amplifier. Install all tubes. 

  2. Power on the amplifier and run it for 20 min with the bias turned all the way down. To do this turn the adjustment pots counterclockwise until they click to indicate the lowest setting has been reached. (All amplifiers are shipped with the bias turned all the way down.)

  3. Now adjust the bias to the correct setting. 

    • EL84/7189 is 30 milliamps plus or minus +/- 5 milliamps.

    • EL34/6CA7/KT77 is 50 milliamps plus or minus +/- 5 milliamps.

    • 6550/KT88/KT90/KT120 tubes is 60 milliamps plus or minus +/- 5 milliamps.

  4. After 60 min has passed double check you bias setting and adjust as necessary.

    When stable at the correct bias setting you have successfully biased your tubes. Periodically check the bias after the amp has run for at least 60 min because KT170 tubes take a while to reach stability.

HOW TO BIAS THE KT 150 and KT 170 POWER TUBES

KT 170 tubes take some time to settle as compared to the other power tubes. Please follow this guide to make sure they have a long life. 

The meter reading for KT150/KT170 tubes is 70 milliamps plus or minus +/- 5 milliamps.

  1. When you get your amplifier. Install all tubes. 

  2. Power on the amplifier and run it for 20 min with the bias turned all the way down. To do this turn the adjustment pots counterclockwise until they click to indicate the lowest setting has been reached. (All amplifiers are shipped with the bias turned all the way down.)

  3. Now adjust the bias to 40ma. 

  4. After the 20 min has passed at 40ma adjust the bias to 60ma.

  5. Wait another 60 min and adjust the bias to 70ma.

  6. When stable at 70ma you have successfully biased your KT170 tubes. Periodically check the bias after the amp has run for at least 60 min because KT170 tubes take a while to reach stability.

TUBE ROLLING - CHANGING TUBE TYPES - F22/F35/F100s

  • If changing from EL34/6C7/KT77 to 6550/KT/88/KT90/KT100/KT120/KT150/KT170 please turn each bias potentiometer V1, V2, V3, and V4 counter-clockwise at least 6 full turns or until they click while the amplifier is POWERED OFF or IN STAND BY MODE.

  • You must re-bias every time that you change/replace a tube in the amplifier. Please follow bias instruction for your new tube type found above.