6l6 bias calculator amplifier Tube Type and Plate-to-Cathode Voltagemust be entered for all calculations on this we Bias is high frequency alternating current applied to minimize distortion in a magnetic tape recorder. The 7868 is only rated at 19 watts. This is a negative voltage. And really, the 1 ohm method works for both fixed bias and cathode bias circuits. 7 * 30/450) = 47mA. With the switch on the back of the amp in 6L6 mode I can only get these up to 29mA with the bias adjust maxed out. You can: choose among most common power vacuum tubes (I am slowly adding more), set the operation modality, among I believe the only reason manufacturers ever used cathode bias in AB1 amplifiers was the cost savings. Tube Bias Calculator II *Merlin Blencowe believes up to 85% is OK for Class AB Fixed Bias Amps. Jack Hoffman Amplifiers Tube Amp Forum, How to Bias a Fender Concert amp. Our bias probe measures true bias current. DISCLAIMER: LORD VALVE (W. Bias refers to the high-frequency alternating current applied to a tape recorder to minimize distortion. Start to bias 6l6 tubes, or any other types, by plugging in the bias probes and the new power tubes. The formula for biasing is the plate dissipation of the tube (12 watts for standard EL84’s or 9 watts for the JJ EL844’s) divided by the plate voltage (let’s use 350 for this example) times . Carefully remove the old, worn out tubes from the amplifier. No-calculation examples: A higher voltage (450v) deep class AB amp might use a 4k primary (possibly smaller), while a lower voltage (350v) hotter class AB amp might use a 6. 3. www. Each tube sample was installed in the same custom built, fixed bias single-ended guitar amplifier (see schematic) with a Fender black face style preamp circuit. Bias Rite Instructions; Chassis Dimensions; Cabinet Dimensions; Cabinet Covering Swatches (Includes Handle Pics) 6L6GC – 30W. . 4 to 1. By LordRiffenstein November 4, 2005 in Amps. tedweber. Plus modern Fender 6L6 amps tend to specify an idle cathode current of 30mA. Welcome To the Hoffman Amplifiers Forum December 28, 2024, 10:30:43 pm: Welcome, Guest. 3 Gain of the voltage amplifier with self-bias; Chapter 4: Integrated push-pull amplifier. 7 will just get you out of crossover distortion and you can go as high as . A formula example is this: (0. He measures the bias on the convenient pins on the printed circuit board. 85 percent but you will wear out the tubes quicker! 12 watts divided by The spreadsheet is set up to calculate bias for amps using class AB1 mode which is basically what most amp output stages use. This is an online calculator designed to determine the bias of a tube amp in amperes or milliamperes (mA or A). Global Moderator; > what to bias the 6L6's at "Bias" includes plate voltage. Based on the chosen parameters, the calculator will determine the Amps without adjustable bias include Mesa-Boogie amps, some Peavey amps, and even some Fender amps (early versions of the Hot Rod Deluxe/Deville and Blues Deluxe/Deville, for example). This tube amp bias calculator allows you to select the tube type and amplifier class type (AB or A) to calculate the current. Since 2006 we have offered a single octal bias probe for use with a Multimeter. Some like to use 60% thinking it may extend the tube life. Search for a biasing tube amplifier calculator online. Start new topic; Recommended Posts. Plate Voltage: Hot (70%) Avg (60%) Cool (50%) 300V: 70mA: 60mA: 50mA: 325V: 65mA: 55mA: 46mA Any work inside a tube amp is not "safe," so exercising due caution, this method would not be a threat to you. Requires separate digital volt-ohmmeter capable of FINAL AMP KIT SALE Take 10 off Amp Kits till Monday 12/23 with coupon code FINAL. -User Name-Password Home; Help; Search; Login Try setting the bias with this -bias calculator, I like 60%, don't go more than 70% dissipation. g. The drive with the 6SN7 is a full 8dB lower allowing more voltage drive to reach full power. com. It seemed like, as i recall whatever the numbers were for mA, I was say at 40mA well biased at about 70% (I'm making these numbers up to try and recall 'roughly' what I The measured plate voltage was 425VDC, and the measured plate current was 39mA. Hoffman Amplifiers Tube Amp Forum, Rob Robinette's bias calculator . 2 Cathode bias or self-bias for vacuum tubes; 3. The best way is to observe the live current. Click any Calculate button to see the recommended tube bias currents in milliamps. This is why fixed bias amplifiers - which don't experience the bias change relative to output level - can generally be set to idle at lower current, which promotes longer tube life. TUBE BIAS CALCULATOR (for push pull class AB1/AB2) For 8-pin power tubes such as 6L6, 6V6, 5881, 6550, EL34, KT88, KT66, KT100, etc. Whether you're a seasoned Use this tool at your own Risk. From 360-400 to 480V, the load should be 1. Bias Settings For Safe Plate Dissipation Class AB: 70% CALCULATE PLATE DISSIPATION Based on Plate Voltage and Cathode Current Readings. In a tube amplifier, bias is used to determine the ideal current flow in the tube when Use this calculator when you measure the actual plate current. Cathode bias amps must run HOT. With that, and the info from the tube type, a tech can do the math and figure out the appropriate bias range. If this number seems small that is because it is in amps rather than the typical milliamps we’re used to seeing. Plate dissipation is calculated by measuring plate voltage and plate current, I like using the Rob Robinette - Bias Calculator to plug the measurements into to make the math a bit easier/quicker. Welcome To the Hoffman Amplifiers Forum December 07, 2024, 05:29:27 pm: Welcome , Guest. This website uses cookies to ensure that you get the best experience. Arrow points to the insertion index notch. True 5881 tube are about 23-24 watt max. Rather than the suggested 70% of maximum plate dissipation, I was sitting at approximately 55%. If you want to try them I strongly suggest you try to power up the amp with one and monitor the cathode bias voltage as the amp comes up to make sure the voltage The bias of the amp was set way too high when I bought it used and caused red plating in a TAD 6L6 WGC as it goes, plugged the bias master in, replaced with a pair of NOS Jan Philips and set bias near to the top end of what they recommend for this amp and now it sounds fantastic and I have the price of mind that everything is as it should be. We will continue to offer these because in conjunction with a Multimeter this is the most cost effective tool for measuring true plate current allowing you to accurately bias your amp. Skip to content. 6l6gc's are 30 watts max plate dissipation per tube. ) Logged Willabe. 42mA), but do not On the bias calculator I should have these at 38mA for a cool 50%. 00 and available in our online store and can be used with 6V6 - EL34 - When biasing to 70% or whatever percent you’re looking for you simply multiply the answer by that number divided by 100. The 6L6GC is a type of beam power tube employing a beam-confining electrode at cathode potential in place of an actual suppressor grid. There are many web sites that explain setting bias. You must enter Tube Type and Plate-to-Cathode Voltage above before calculating Tube Dissipation. Some smaller amps with 6V6 power tubes Use this calculator to determine the bias current for an amplifier’s power tubes. 4. The schematic shows 6L6GC power tubes. Matched output tubes and proper bias are the ingredients to quality sound and Amps ; 6L6 tubes and bias 6L6 tubes and bias. Also, the idea that it's OK for bias to change This will bias the 12AT7 even farther away from grid current, and into a more linear area of its operation. You would need to input your power tube’s details and the voltage you got earlier. Grid bias calculator mU factor (approx): 8 Cgp: 0. It can be built for CW as well as AM operation. He sets the It is fixed bias but doesn't appear to have adjustable bias. Overview. Then by R=V/I, the Load Impedance must increase to properly absorb the power. Or, as Chris suggested, you could choose a more linear driver tube. 5 Amplifier classes; 3. 1 Single Ended vacuum tube amplifier; 4. Please login or register. 5 250ohm shared impedance: 9,000 output power: 24w 3. Now, when you use the bias calculator on the Weber-site, they do make a difference between 6L6, 6L6GC and 6L6WGB and for the same plate voltage, they all have AMPS. Customer ” Joe” puts his four brand new matched Tung Sol 6L6GC-STR into his amp and he checks the bias on each of the valves. It requires running the output tubes much harder at idle than if they were fixed biased. Bias voltage is like a control valve that regulates the current through the power tubes. WHITTAKER DBA NBS ELECTRONICS) WILL TAKE NO RESPONSIBILITY FOR ANY INJURIES OR DAMAGE SUFFERED BY ANYONE AS A RESULT OF THE MISINTERPRETATION OR MISAPPLICATION OF THE INFORMATION CONTAINED IN Here is a good read and explanation of how to measure and set bias in a Tube amp. Posted November 4, 2005. With those operating conditions it would also be able to swing more volts into the 6L6 grid. 4mA of idle plate current. You must re-calculate after changing values by clicking any Calculate button. In these calculations, 5% of the cathode current is assumed to be screen current Given below is the tube amp bias calculator to find the bias in ampere or milliampere (mA or A). jpg (429. It looks like yours is a Fixed Bias amp so I would use 70% of max plate dissipation per tube. Please login or So, tried the 6L6GB (19watt The increase in bias voltage pushes the tube toward class B operation where no current flows at the zero-reference line of the signal. Here is s video to simplify the process. Tube Bias Online Calculator. The cheapest solution. 44 kB, 1224x1584 - viewed 169 times. There's several ways to skin that cat, but Fender has made it easier by including a 1Ω resistor between ground and the 6L6GC's cathodes as the "bias 425V B+ 6L6GC 4k center tapped ot Push pull class A Fixed bias TDSL says this for cathode bias: B+ 360 Vg2 270 Ia 50 Ig2 9. -User Name Robinette Calculator for 6L6GC. For use with octal tubes EL34, E34L, 6CA7, KT66, KT77, 6L6, 6V6, 5881, 6550, KT88, KT90. The 6CG7 (same as 6FQ7) would be a very good choice. If Vp is increased, Ip must DEcrease so the tubes don't melt. Select your Plate is pin 3 and Cathode is pin 8. And know that even 6L6GC data sheets often reprinted conditions that were on the original 19w 6L6 data sheet. These probes are $25. As long as you know (or can test) the plate voltage in your amp, and have a way to measure the idle current, you can determine where to bias it, using our calculator. 4 pF Cin: 10 pF Cout: 12 pF The final 6L6 amplifier runs straight through, not frequency doubling, on all bands. The calculated design power sensitivities for both drivers are recorded in my notebook. Our bias tools are easy to use, and provides a fast and accurate way to get the best sound from of your amp. Biasing Tube Amplifier Calculator; Biasing a Tube Amplifier; Build Guide - 2 Tube Regenerative Radio; Build Guides for Pedals; Step 6: Slowly turn the bias pot towards hot until you get a reading of about 35mA (ideal bias point for 6L6GC). Tube Dissipation Using Cathode Resistor Voltage Drop. If you have for example a 250 ohm cathode resistor for cathode bias, adding a 1 ohm resistor in series with that won;t change the bias to the tube HOW TO BIAS YOUR AMPLIFIER. 8 times higher, 7K to 9K. (Title Changed) Welcome To the Hoffman Amplifiers Forum December 26, 2024, 03:06:37 am: Welcome, Guest. Classic 50’s American Kits; Classic 60’s American Kits; Classic 60’s British Kits Bias Calculator. 6 Biasing techniques. Step 7: Use your ears to determine the best sounding bias point for the EL34s (e. 6k primary. 1. Maybe I should turn the bias adjust all the way down and flip the bias switch on the back of the amp to EL34 and see where the bias is? To calculate the ideal bias range for any amplifier a tech will first measure the amp’s plate voltage. Enter the plate voltage and type of power tubes to get the bias current at various levels of plate dissipation. Enter Plate Current: DC With our tool, you can easily determine the ideal bias voltage and bias current for your tube amp, ensuring optimal performance and unmatched sound quality. and it wasn't very low below the 70% I bias at, but I didn't calculate the % diss at that point. Members; LordRiffenstein. 6. 2 Impedance of an output transformer Cookies & Privacy. Kits. More Information. In the case of a tube amp, bias is used to determine the ideal current flow in the tube when the amp is not in use. 1 Fixed bias for vacuum tubes; 3. The Granger Amp bias probe measures in milliamps by insertion into the cathode This calculator allows you to compute and tune loadline and operating point of tube amplifiers’ power stages. Bias is an alternating current of high frequency which is applied to the tape recorder to reduce distortion. 1 Output stage, or power stage. The schematic shows a voltage of -48 at the junction of the two 270K resistors. The Measured Voltage Gain Test Setup. Wait for it to calculate your bias point Hoffman Amplifiers Tube Amp Forum, 6l6 bias pot value question. By visiting the Weber Bias Calculator, and the Tube Amp Bias Calculator, it was advised to set my bias to yield 49. In many tube amps, the bias on the power tubes is adjustable. Simply multiply the outcome by 1,000 to get. It uses a 6AG7 oscillator (can be modified for VFO) and parallel 6L6s running 75 watts input on 80, 40, 20, and 15 meters. That is for 6L6 tubes so I'm not sure what the 7868 bias at. jzwp zxedg cdis ytgo uxzts spcd ocusjwx ywmq odkg evhp