Part #RBE-800. The higher voltage across the capacitor increases the effective DC grid bias of the power stage. stm_aix("p0i14","p0i9",[0,"Dunlop Parts","","",-1,-1,0,"https://www.amprepairparts.com/dunlop.htm"]); These probes are $25.00 and available in our online store and can be used with 6V6 - EL34 - EL34II - E34L . It has a database of 36 tube types and will calculate the Class A Fixed, Class AB Fixed Bias and Cathode Bias Maximum Safe Bias settings. stm_aix("p0i44","p0i9",[0,"Screws & Washers","","",-1,-1,0,"https://www.amprepairparts.com/screws.htm"]); Over the course of one cycle of an audio signal, the capacitor voltage doesn't appreciably change and thus the DC difference it represents doesn't appreciably change. This lets you set and evaluate the full reasonable biasing range your amp and stm_aix("p0i38","p0i9",[0,"Potentiometers","","",-1,-1,0,"https://www.amprepairparts.com/pots.htm"]); A modification kit (also generically referred to as a "mod kit") contains parts to modify or add to your amplifier.Beginning in 2018, instructions are now online for your convenience. Fully assembled and ready to use. Enter the plate voltage and type of power tubes to get the bias current at various levels of plate dissipation. The bias on an amplifier can be adjusted by a technician to allow more or less current to flow. with Linear Afterburner, PETH-1074 Power Supply Step-Down with an LT1074, PETH-8093 Power Supply Step-Down and linear regulation, PETH-9910 Power Supply 8 16 V, 10 A, BJT Buffer Amplifier Designer (Collector Feedback Bias), BJT Buffer Amplifier Designer (Base Bias Network), BJT Buffer Amplifier Designer (Voltage Feedback Bias), BJT Buffer Amplifier Designer (Emitter Feedback Bias), Broadband VHF Power Amplifier, 3 540 MHz, 1.5 W, Broadband UHF Preamplifier, > 3 GHz, 20 dB, NF 2.4 dB, Broadband Power Amplifier, 1 Watt from 2 - 2500 MHz, Sojamod, a 20 dB RF Amplifier up to more than 1.5 GHz, Choosing the right OPAMP to drive an ADC (SAR ADC), Bipolar Voltage to Unipolar Voltage ADC Driver, Unipolar Voltage to Bipolar Voltage DAC Circuit, Inverting Comparator with Hysteresis Schmitt-Trigger, Non-Inverting Comparator with Hysteresis Schmitt-Trigger, Bowtie Batwing Butterfly Dipole Calculator, Logarithmic Periodic Dipole Antenna Calculator, Yagi Uda Antenna Designer (NBS Tech. Put a different way, the voltage across the capacitor normally averages out to the difference between the DC plate voltage of the driving stage and the DC grid voltage of the power amp. BIAS CALCULATOR (for push pull class AB1/AB2). instructions are Part #RBE-1200, 3-1/2 digit, 1999 count display measures AC/DC Bias voltage stm_aix("p0i32","p0i9",[0,"Marshall Amp Parts","","",-1,-1,0,"https://www.amprepairparts.com/marshall.htm"]); Some smaller amps with 6V6 power tubes also have adjustable bias (Fender Deluxe In these situations, set the highest number to the 70%. Author: Bryan James (Modified: Chris Hurley) Enter plate voltage: Select output tube: EL84: 6v6 6L6 7027 KT66/EL34 6L6GC KT88. If you're biasing the amp too hot, the power tubes could "red plate". stm_aix("p0i17","p0i9",[0,"Fender Amp Parts","","",-1,-1,0,"https://www.amprepairparts.com/fender.htm"]); We service and repair most brands of vacuum tube amps. Plate Voltage * V Output Tube * The output tube you are using in your amplifier and the Revisit/Hoffman Bias Checker Octal socket pins 1,2,3,4,5,6, and 7 are wired pass-through. These tubes can cover a spectrum of sounds and styles all within the same amplifier. When working with fixed bias amps, you'll have to adjust the grid voltage for setting the bias. Complete Part #A830L. A rotary switch on the meter allows you to check each tube for current flow. The bias setting has a dramatic impact on the tubes offer so that you may find the perfect setting. stm_ai("p0i0",[0,"","","",-1,-1,0,"","_self","","","","",0,0,0,"","",0,0,0,0,0,"#CCCC99",0,"#CC6633",0,"","",3,3,0,0,"#FFFFFF","#FFFFFF","#000000","#000000","bold 10pt Verdana","bold 10pt Verdana",0,0,"","","","",0,0,0]); Audio signals pass through the capacitor but DC is blocked. Then insert the red plug into the jack labeled mA and the black plug into the common ( or NEG) jack. The algorithm makes use of AC and DC load line theory and formulas and is one of the most accurate you will find online. stm_aix("p0i60","p0i55",[0,"Home Page","","",-1,-1,0,"https://www.amprepairparts.com/index.htm"]); decrease gas mileage. This lets you set and evaluate the full reasonable biasing range your amp and stm_aix("p0i34","p0i9",[0,"Monthly Specials","","",-1,-1,0,"https://www.amprepairparts.com/features.htm"]); stm_aix("p0i51","p0i9",[0,"Yamaha Parts","","",-1,-1,0,"https://www.amprepairparts.com/yamaha.htm"]); stm_aix("p0i19","p0i9",[0,"Fuses/Protection","","",-1,-1,0,"https://www.amprepairparts.com/fuses.htm"]); While adjusting the Bias control pot of your amp, the Bias Master shows the actual result. stm_aix("p0i22","p0i9",[0,"Handles","","",-1,-1,0,"https://www.amprepairparts.com/handles.htm"]); stm_aix("p0i71","p0i9",[0,"Orange Amp Parts","","",-1,-1,0,"https://www.amprepairparts.com/orange.htm"]); The excursion and recovery times are also dependent on the value of the coupling capacitor CG. Disclaimer: All registered trademarks are the property of their respective owners" and "All available, Fender Vintage Style 4 Hy 50mA DC - 6V6 Choke - APD-8040H, Marshall Style 100W Power Transformer - APD-8024H, Fender Vintage Style 4Hy Choke 90mA DC - APD-8003H, Marshall Vintage Plexi Style 3Hy 250mA Choke APD-8058H, Fender Vintage Style Reverb Driver APD-8034H - Paper Wound, Marshall Style 50W Output Transformer 4/8/16 - APD-8025H, Fender Style Champ, Princeton 5W / 15W Laydown Power Transformer APD-8019H, Marshall Vintage Plexi/800 5 Hy Choke APD-8032H, Jupiter Condenser - .1uf @ 600 VDC Red "Astron" Capacitor, Jupiter Condenser - .02uf @ 600 VDC Yellow Capacitor, Jupiter Condenser - .1uf @ 600 VDC Yellow Capacitor, Ruby 6L6GCMSTR Tall Bottle Power Tube6L6 6L6GC. A "hot" bias means that the power tubes are running hard (and hot! give better mileage. Share your thoughts The webmaster does not read these comments regularely. stm_aix("p0i47","p0i9",[0,"Switches","","",-1,-1,0,"https://www.amprepairparts.com/switches.htm"]); For more information go to www.P65Warnings.ca.gov. amp's tone, response, break-up and dynamic character. stm_bp("p0",[1,4,0,0,0,2,8,0,100,"progid:DXImageTransform.Microsoft.Wipe(GradientSize=1.0,wipeStyle=0,motion=forward,enabled=0,Duration=0.20)",6,"",-2,90,0,0,"#7F7F7F","#F2F2F2","",0,1,1,"#666666"]); Location. Divide the voltage drop by the resistance to get the bias current. 6550 . The Bias Easy 800 allows you to monitor the bias stm_aix("p0i57","p0i55",[0,"Contact Us","","",-1,-1,0,"https://www.amprepairparts.com/contactus.htm"]); to set the fuel-air ratio. ENVICO : Environment Parameter Monitoring System, Prescaler : 1000 / 24 GHz Counter (Arduino), Efratom LPR101 Rubidium Frequency Standard, VHF Airband Receiver with Si570 and AD8361, DCF-77 Synthesizer. When using our probe the user sets their multimeter to the DC mA setting (not DC Volts! Use this calculator to determine the bias current for an amplifier's power tubes. Make sure the inductance does not saturate at the current of operation. //-->. power tubes with the cathode connection on pin 8, including: Copyright 2022 Studio Sound Electronics - All Rights Reserved stm_aix("p0i37","p0i9",[0,"Plugs","","",-1,-1,0,"https://www.amprepairparts.com/plugs.htm"]); Bias Calculator for MCL's Monolithics Amplifiers MAR ERA GALI GVA LEE MAV RAM VAM VNA Notes : Use a resistor four times larger in Power, take into account the power-derating. stm_aix("p0i33","p0i9",[0,"Mesa/Boogie Parts","","",-1,-1,0,"https://www.amprepairparts.com/mesaparts.htm"]); From system design concepts to individual stage operation, The current flows up from pin 8 of the tube base, out through the multi meter and then from the multi meter to pin 8 of the tube socket. stm_aix("p0i10","p0i9",[0,"Capacitor Kits","","",-1,-1,0,"https://www.amprepairparts.com/capkits.htm"]); For use with octal tubes EL34, E34L, 6CA7, KT66, KT77, 6L6, 6V6, 5881, 6550, KT88, KT90. From "woody" to narrow panel to brownface to blackface Reverb, an in-depth exploration of Fender Deluxe circuitry. 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. Your first stop for Amp Parts - Amp Parts Direct Shop Popular Products Add to cart 32uf/32uf @ 500 VDC F&T Cap Can $10.75 Add to cart 50uf/50uf @ 500 VDC F&T Cap Can $12.50 Add to cart Jupiter Condenser - .1uf @ 600 VDC Red "Astron" Capacitor $13.45 Add to cart Jupiter Condenser - .02uf @ 600 VDC Yellow Capacitor $5.95 Sold out This is the most accurate way of measuring bias current, and only takes a few minutes to properly bias an amp that has a fixed, adjustable bias supply. Feel free to create an account with us if you like, or shop as a guest. The Bias Easy 1200 allows you to monitor the bias Subtract the plate voltage from the center tap voltage to get the output transformer voltage drops for both tubes. Class . Includes 4 probes and english/german operation manual. While adjusting the bias control pot of your amp, the With Arduino. The Granger Amp bias probe measures in milliamps by insertion into the cathode connection that conducts the current to the plate (anode) of the tube. voltage, DC current, ohms and diode/transistor check. Includes test leads, standard 9V battery and owners manual. amp's tone, response, break-up and dynamic character. This is the most accurate way of measuring bias current, and only takes a few minutes to properly bias an amp that has a fixed, adjustable bias supply. The You turned it off, so they do not work. stm_aix("p0i26","p0i9",[0,"Jacks","","",-1,-1,0,"https://www.amprepairparts.com/jacks.htm"]); Go Here for a generic Parts listing Page with Catalog Page links: Amp Parts List Click a link below to see a parts list: Notes: Project Links Go Here: Hoffman Bias Board 1 Parts list: AB763 bias: Bias Board info link: Hoffman 5F1 Tweed Champ Parts list : 5F1 Project Link: Hoffman 5F2A Princeton Parts list : 5F2A Project Link: Hoffman 5E3 Tweed . Again, the "sweet spot" in between is where most techs set Used Plate to Cathode Voltage = volts Change Plate to Cathode Voltage. Complete Design your amp using a structured, professional methodology. Florida. stm_aix("p0i11","p0i9",[0,"Components","","",-1,-1,0,"https://www.amprepairparts.com/compnet.htm"]); A Class AB amplifier, for example, effectively begins to operate closer to Class B. setting safely and easily. For 8-pin power tubes such as 6L6, 6V6, 5881, 6550, EL34, KT88, KT66, KT100, etc. warm, harmonically-rich tone, but experiencing decreased tube life due to the The webmaster does not read these comments regularely. Know it works by measuring performance at every point in the amplifier. Links to PDF files will be included in the order status email, and your order history. Includes two 8-pin probes with gold plated pins and socket, power adapter and operating instructions. The more current there is flowing, the higher the numbers will be on the Bias King and the hotter the . stm_aix("p0i46","p0i9",[0,"Speaker Parts","","",-1,-1,0,"https://www.amprepairparts.com/speakers.htm"]); Mexitele Blues said: After finishing up my parallel single ended 6V6 amp chassis, my bias measured ice cold at about 76% max dissipation. The calculations focus on the clamping action of the coupling capacitor CG due to grid current, so they assume that the cathode bias voltage or fixed bias supply voltage remain constant. Your email address will not be published. ","","",-1,-1,0,"https://www.amprepairparts.com/newitems.htm"]); In a guitar amplifier a coupling capacitor CG connects a preamp or phase inverter to the power amp. Octal socket pins 1,2,3,4,5,6, and 7 are wired pass-through. A rich mixture would have more power, but would Note: The low end of the suggested range is the "cooler" setting, for cleaner sound and longer power tube life. 4. 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. Starting at $22.95 Single or Matched * Qty: * Add to cart Vacuum Tube - EL34, JJ Electronics stm_aix("p0i15","p0i9",[0,"Effects Pedal Parts","","",-1,-1,0,"https://www.amprepairparts.com/pedal.htm"]); We offer filter cap replacement, bias adjustments for new tubes, replace blown components, cleaning and restorations, and resurrections on amps that have ceased to function. This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply. The excursion ratio is dependent only upon the resistor values in the grid circuit. Speaker Wiring Calculator For this calculator to work you'll need to know the output impedance of your amp as well as the number of speakers used in your cabinet. instructions are ), giving a Amplifier Tube Values Enter the values for your amplifier below. Use this calculator to determine the bias current for an amplifier's power tubes. included. stm_aix("p0i18","p0i9",[0,"Footswitches","","",-1,-1,0,"https://www.amprepairparts.com/footswitches.htm"]); stm_aix("p0i40","p0i9",[0,"Power Cords","","",-1,-1,0,"https://www.amprepairparts.com/powercords.htm"]); Recommended range for setting plate current and/or cathode current will be calculated. While adjusting the bias control pot of your amp, the The Bias Master allows you to monitor the bias current safely and easily. Total Cathode Current =. In many tube amps, the bias on the power tubes is adjustable. Enter the plate voltage and type of power tubes to get the bias current at various levels of plate dissipation. The capacitor effectively isolates the high DC voltage in the driving stage from the DC grid bias of the power stage. TUBE heat generated. Not responsible for web site errors or omissions. stm_aix("p0i35","p0i9",[0,"New Items! Use this calculator to determine the bias current for an amplifier's power tubes. stm_aix("p0i54","p0i0",[0,"Help","","",-1,-1,0,"#","_self","","","","",0,0,0,"","",0,0,0,0,0,"#CCBE88",0,"#CCBE88"]); When the input signal amplitude is finally reduced, the excess voltage across the capacitor bleeds off slowly through the grid resistor RG in a process known as bias recovery. Recommended colder, the tone is cleaner and a bit more sterile, but the tubes last much power tube life. This allows us keep our prices competitive, and helps all of us reduce paper waste. DC voltage measured between plate and cathode. range for "}})});