6v6 Bias Voltage


Bias Tube Amplifiers ‘Hot’ If the bias current is set too high, the valves will glow hot and will have a shorter life. From this you can see how the grid bias point necessary for proper bias ties into gain and drive power. This value is 22. Output Pentode Quick reference data • Anode current Ia=48mA • Transcoductance S=11,3mA/V • Amplification µg2g1=19 • Output power Wo=6W Heating Indirect by AC or DC; parallel supply. I will measure screen voltage. Figure 1-25. IS = Internal Shield (Electrostatic). You'll need to check with the guys at Dr. 0W Product. I did some googling, read that 52 mA was probably what fried the 470 and its cap and the tube and went with a replacement resistor with a value of 1. The scaling of the pot was such that I was able to get the bias down enough to make the 6V6 work correctly with no modifications. This bias meter is designed so you do not have to touch. In the final installment of this series we will discuss the benefits of negative feedback and the drawbacks of using too much of a good thing. Page 2 of 2 < Prev 1 2. The KT88 fits a standard eight-pin octal socket and has similar pinout and applications as the 6L6 and EL34. If 6V6 valves are fitted in the amplifier, the bias settings should be reduced to 25mA (maximum) on the ustom setting using the User Interface and Bias Runner Software. Grid resistors 7 and 8 are connected to a negative DC bias supply instead of ground. It also has all of the options including Mercury Magnetics trannies for 6V6 or 6L6 power tubes(15-32W), push-pull bright and mid-boost pots, negative feedback pot, and easy access bias pot and test points on the rear panel. To allow high efficiency of the regulator, the. I was curious and bought a few plus adapters and tried them in my 1956 fender tweed deluxe and blackface Princeton reverb and quickly went about buying about 100 more as they sound great. 5 W is normal. 5 vrms and 111 wp-p at 58vp-p output. This list is our current tube type, location and bias points for all of the Dr. if you aren't familiar with the SAFE procedure for working around high voltage amplifiers, take it to a qualified amp tech! Bias Range (mA) Notes: 6V6: 22mA - 30mA: 22mA is a good starting point for Fender BF Deluxe and Princeton amps, 25mA-28mA. The second point illustrated is that there is a bias voltage. ; BiasPro VI-8C: Bias and plate voltage combo probe for common 8pin octal tubes. In cathode bias a small value resistor is placed between the cathode and the ground so it develops negative voltage on the cathode thus achieving bias. Adjust the bias to between 20 to 25mA which is a conservative setting for most all amps while you note the DC plate voltage and use the formula above to calculate the bias you want. JJ's rugged construction of this tube offers high reliability without any compromise to the sound. 00 and available in our online store and can be used with 6V6 - EL34 - EL34II - E34L Bias is calculated using the voltage and measured current on each tube or pair of tubes. To help explain this, refer to figure 1 below. The peak grid-to-grid is twice the bias. 0 Store: AK985 Audio Store. to EL84) The YJUni is a direct pin to pin converterwith no internal voltage dropping or bias components. Understanding 6V6 screen voltages. Calculate Plate Dissipation Based On Plate Voltage And Cathode Current Readings. If we know the voltage across, and the current through, an unknown resistor, we can find the value of the resistor through Ohm's law. This is a direct measurement of the tube’s gain, but requires an AC signal source, an AC meter, and ability to adjust the operating point for vastly different. I was curious and bought a few plus adapters and tried them in my 1956 fender tweed deluxe and blackface Princeton reverb and quickly went about buying about 100 more as they sound great. Bias Tube Amplifiers ‘Cold’ Too low a bias current and the tubes will last longer but the sound tone will be affected. Fixed bias power tubes have their cathode connected directly to ground and a negative DC voltage applied to their control grid. From this you can see how the grid bias point necessary for proper bias ties into gain and drive power. You can Get the reading direct from the current meter. 1 Emerson 1 Motorola ***** Tested on our proprietary tester , the E3444 Triplett/Westmore 501 : It's a Triplett 3444 / Westmore 501 that has been enhanced. Coincidentally the bias voltage for the 6V6 and EL34 are in the same range with 400V B+, which made it easy to do. (If the power amp is fixed bias, then the circuit looks a bit different. What voltage difference do I want ideally. -2 6V6 or 6L6 Power Tubes. NOS 6V6 tubes usually can't handle more than 300 volts on the plates. Now the total voltage needed to power the heaters is 6. These are exactly 6v6gt tubes with a different Loctal base. 80x12 boat jet ski LOAD C 480 12 $59. 80-12 LRC 6 PR Bias Trailer Tires 4. The included original instruction manual has a detailed description of tube biasing, as well as listing all of the possible combinations of power tubes you can run in the Renegade – 6L6/5881, EL34/6CA7, E34L, 6550, 6V6, KT66, and KT77, all with the appropriate bias voltage range. The last 50UF capacitor was installed on the pot wiper. 6 out of 5 stars 26 $16. 6V6 Tube Advice for 5F1? Discussion in 'Shock Brother's DIY Amps' started by PorkChopExpress, Jun 27, 2020 at 8:59 PM. I set mine at 33ma for 6V6 and 38ma for 5881. This tester uses regulated power sources for the bias, plate, & screen voltages, as well as modified operating & testing procedures. 0v ac with bias 0 to -40 vdc; Range C signal voltage is 5. Filament voltage is also controlled. based amplifiers. Its unique circuitry creates a platform that reveals the true character of the power tubes to a surprising level. A tube that gives lower voltage may not be able to handle the current of. The output of this small amplifier in which a 6V6GT output pentode is connected as triode is about 4. 6V6S - A modern production, large plated tube, heater current 500mA, with a higher plate and screen voltage rating. It has an international octal base (indicated by the '3' in the part number) and is found mainly in the final output stages of audio amplification circuits and was designed to be suitable as a series regulator by virtue of its high permissible voltage between heater and cathode and other parameters. We know that the cathode voltage is 2. Bias 2 -20 volts bias- 10ma. We are doing the final tweaking of a new single channel amplifier that will be able to run 6V6's at 15 Watts OR 6L6GC's at 35 Watts (with a simple re-biasing which will have jacks and setup on the back panel). If the tube required 100 volts or so bias in AB1, and had the same anode effective RMS current, drive power would double. Jun 28, 2020 at. The JJ 6V6 can even be used in place of a 6L6 in some amplifiers. 9 watts) Divide your desired wattage by the plate voltage that you wrote down from step 2. Ive always used 14 wattsbut you could try to track down the spec sheet for any NOS piece. My 5E7 Bandmaster clone is currently fairly “detuned” — it’s running off half of a 5Y3, and I rfverb it in cathode-bias mode most of the time, so the plate voltage is around V. 2 6L6s is 5k so I assumed (you know what that means) that a transformer pair for a 6L6 amp would work well. Plate voltage was 158V, and cathode voltage was 6. The pentode has a mutual conductance of 7500umhos, compared to a 6V6's 4100umhos. This tester uses regulated power sources for the bias, plate, & screen voltages, as well as modified operating & testing procedures. 2 Strong Tung Sol 6V6 Vacuum Tubes. EL34 PP output + Here is a scope shot taken a t 1000hz just before clipping into an 8 ohm load. The most accurate method to test tubes, the curve plots can actually be compared to the printed examples for each tube type that appear in the manufacturer technical data sheets and books. No biasing needed for 6V6 tubes because they can only be used in cathode bias position. 4 - 5 = 288V, and this indicates a grid. This is a fixed bias amp and the bias on these tubes is controlled by negative voltage to the control grids of the 4 EL84 output tubes. > Fender 5E3 Tweed Deluxe / 5E5 Tweed Pro. New user coupon on orders over US $4. Buy from our wide selection of 6 Bias now. We love this combo! You can also sub the 6L6 family along with the EL-34 for more headroom due to the extra beefy Transformers. 2 Voltage 285 Volts Plate Dissipation 12 Watts Grid No. Select your tube type and amp class (Class A, Class AB Low, Class AB, or Class AB High) and enter your Plate Voltage or B+. The biasing of the tube is set to about 70% of max power with a plate voltage that is closer to what the vintage amps had than what is often used today. This tester uses regulated power sources for the bias, plate, & screen voltages, as well as modified operating & testing procedures. (Converts 6L6, EL34, 6550, 7027, or 6V6 to EL84) The YJS is for amplifiers with fixed bias power tubes. The bias meter is very easy to use: NOTICE: Guitar amplifiers have very high voltages that can cause harm to you. So, I simply adjust the bias of my amp such that the voltage across R reads “0. EL34 24 Watts Max. I used a CRCRC circuit to keep AC ripple low with 2K, 50uf, 2K, 50uf, 5K pot and 5K resistor to ground. 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. generally use 6L6 or 6V6 devies. > > Hopefully plate voltage will be low enough for the 6V6. Note that the measured bias voltage across the cathode resistor. Put the 7c5 in the adapter and your good to go. For a 6L6GC the maximum plate dissipation is 30 watts. Page 2 of 2 < Prev 1 2. The all new 6V6EH combines a specially developed cathode coating, careful alignment of the grid, and tri-alloy plate material to create a rugged, wonderful-sounding 6V6 that performs flawlessly up to 475 volts. Biasing: Now we know the screen voltage will be 300 - 7. bias definition: The definition of bias is something that is diagonal or slanting. 6V6 tube has a maximum designed plate dissipation of 14 watts. Filament voltage is also controlled. K = Cathode. The peak grid-to-grid is twice the bias. Dear Amp Experts, Got a no-name 6V6 clone with a 369EX power transformer that gives around 250v plate voltage, just like the Ampmaker N5X kit specifies when running a 6V6. It has an international octal base (indicated by the '3' in the part number) and is found mainly in the final output stages of audio amplification circuits and was designed to be suitable as a series regulator by virtue of its high permissible voltage between heater and cathode and other parameters. 6V6 Datasheet. The Tungsol 6V6 breaks up evenly from low E to high up the Totally Tweed! The preferred OEM tube of '50s-era Fender Tweed Champ and Deluxe amplifiers The Tungsol 6V6 has a geometry designed to safely handle the higher voltages used in guitar amps " plus heavier plate and grid materials. Bias In the Ampage threads and at the PlexiPalace BBS I found some people recommending to bias Oranges at 32-34 mA. Doesn't "need" to be fixed (actually user-adjusted) bias. The max output of the tubes has more to do with the B+ voltage and the bias voltage, than the input signal. 5v ac (500 mV) with bias 0 to -40 vdc; Range F signal voltage is 0. The formula for calculating the output voltage is based on Ohms Law and is shown below. In the TMC1 I have a voltage divider before the power tube but in this one I used split load plate resistors on the phase inverter. Notice that the peak single grid voltage is equal to the DC bias voltage. The plate voltage on mine is 400V and the grid bias voltage is about -36 to -37 volts - this is posted up somewhere. This tester uses regulated power sources for the bias, plate, & screen voltages, as well as modified operating & testing procedures. HV power supply requirements performed on Duncan PS Software Simulator II (PSUII) The original power supply schematic I posted now deleted above used a voltage doubler thus the high current capacity of the power transformer HV winding. The output transformer as an impedance matching device, works on the principal of reflected load. 95 Fabric Bias Tape Maker 45 PCS Set 6MM 9MM 12MM 18MM 25MM Sewing Quilting Tools. IC = Do Not Use (Internal Connection). Nobsound Vacuum Tube Amp Amplifier Plate Bias Current Probe Tester 8 Pin Socket for EL34, KT88, 6L6, 6V6, 5881, 6550, KT66, KT100, KT120, 7027 (CT1-P, Plate Current) 3. Here's a collection of Bias-modulating "Tremolo" circuits which I use for retro-fitting common class-AB guitar amplifiers, circuits which are mostly based around the high gain 12ax7 dual Triode. 2 -- -- 120 0 1. More auto bias circuits. This is a hotly biased amp! Here are 6V6 plate characteristic curves for a 0V grid. (You have 120 ohms for each pair, and if parallelled you then have 60 ohms. Coincidentally the bias voltage for the 6V6 and EL34 are in the same range with 400V B+, which made it easy to do. Specifically designed for audio amplification, the KT88 has similar ratings to the American 6550 which was designed for use as a servo amplifier. The 6L6 and 6V6, which are BEAM power tetrodes, produce the characteristic "USA / Fender-ish. (Actual Plate Voltage) Example: Octal - pins 3 and 8 9 pin - pins 7 and 3. While “biasing” an amp is the act of adjusting the bias voltage properly in order to set the proper “bias current” thru the output tubes, there’s more to it than that. 2 Kohm voltage divider resistor in stead of 10 Kohm. I've heard a lot of people dropping 6V6's into 1987's and 2204's before, but nobody really goes into any detail. UP Mains Frequently occurring in the US: the PT is not suited for todays Mains voltages. If we know the voltage across, and the current through, an unknown resistor, we can find the value of the resistor through Ohm's law. Taking the voltage drop over the Anode of each tube to the CT of the output transformer will yield the quiescent bias of that half of a push/pull output section (Plus it's much. They will melt quickly if fed 300 volts or more! These tubes are often priced under $5 each and can be a good choice for a low budget amp. 00 and available in our online store and can be used with 6V6 - EL34 - EL34II - E34L Bias is calculated using the voltage and measured current on each tube or pair of tubes. based amplifiers. The second point illustrated is that there is a bias. How you operate the tubes (ultra-linear, bias, plate voltage, operating points, etc. Bias setting for 6L6GC power tubes in a Fender Hot Rod Deluxe. This amplifier may be converted to fixed bias by using any convienient arrangement to supply a negative bias voltage (see other examples herein), eliminating the 250 ohm cathode resistor and 100 uF bypass cap, and using 1650N output transformer. The stock tubes were biased at 58% of maximum plate dissipation. The 5E3 uses cathode bias on the power tubes, just like the preamp. This resistance is in series with the 15 Ohm current sense resistor, making a total of 125 + 15 = 140 Ohms - for both tubes, The bias voltage needed to control the 6B4G's, must be negative with reference to the cathodes of the 6B4G's ( -40 to - 60V or so ) , which means that the cathodes of the cathode follower must returned to a. 6v6 PP 20w Bias Voltage Range 03-02-2013, 01:59 PM. The closest standard value is 360 Ohm. Some people bias 6V6's really hot, but I try to stay below 25ma per tube. Technically, that's a really high static dissipation for a 6V6, but it works fine with old USA-made tubes. 6L6 tubes will draw more heater current and can operate at higher plate voltages. We know that the cathode voltage is 2. I was curious and bought a few plus adapters and tried them in my 1956 fender tweed deluxe and blackface Princeton reverb and quickly went about buying about 100 more as they sound great. 3) Will adding a dedicated screen grid resistor at pin 4 of the 6V6 help lose some of the blocking distortion? (if that's what I'm hearing?). 80-12 LRC 6 PR Bias Trailer Tires 4. Filament voltage is also controlled. This is the best opportunity you will ever have for 7C5 matched tubes. The beam tetrode design of the 6L6 allowed RCA to circumvent Philips' pentode patent. if EL34 get 8 W ,probably to get 6. Single Ended Parallel 6V6 / 6N2P Fix Bias. Tubes are tested in accordance with the manufacturer's specifications; measurements closely align with a laboratory tester built to rigorously measure vacuum tube characteristics. 2pc Tube amp bias probe for el34 6v6 6l6 kt88 6550 5881 7024 "mV" test mode. Adjust the bias trimmer ("pot") until you get a reading across the 1-ohm resistor(s) somewhere in the 30-40 mV range, for everything but 6V6s. The voltage coming out of the bias pot goes to a junction with two resistors, which sends the right amount of separate negative voltage to the grids of each of the 6V6 power tubes. RCAs about the only 6v6 I can use without red plating. This tester uses regulated power sources for the bias, plate, & screen voltages, as well as modified operating & testing procedures. Philco 6V6 GT Vacuum Tube ^^^^^ ***** Tested on our proprietary tester , the E3444. The -26 Vdc bias voltage being applied to the grids of the 6V6 tubes resulted in the 12W power dissipation shown above. You could make a choice based on cost or availability and loose nothing to quality in this group. The first is that the optimum power out is primarily driven by the chosen plate voltage. Non-Adjustable Fixed Bias: This category can be the most labour intensive when it comes to setting the correct bias. I started with a 220k to drop the voltage and I have -31v maximum bias from my trimmer. Select your tube type and amp class (Class A, Class AB Low, Class AB, or Class AB High) and enter your Plate Voltage or B+. This tester uses regulated power sources for the bias, plate, & screen voltages, as well as modified operating & testing procedures. The voltage coming out of the bias pot goes to a junction with two resistors, which sends the right amount of separate negative voltage to the grids of each of the 6V6 power tubes. I've still got 3 of the 6V6 amps and I don't have any of the EL84 amps. If we know the voltage across, and the current through, an unknown resistor, we can find the value of the resistor through Ohm's law. 02 Kohms, and with the voltage drop now at 32. Re: Clarification on Bias Settings for JJ 6v6 « Reply #10 on: October 15, 2010, 10:16:26 am » Just for a differant note I was contemplating Making a 30 watt 59 marshall when I asked this question at a differant forum the consenses was to just make the standard 100 watt set up and put in jj 6v6,s because they could take the high plate current. The heater voltage is closer to 6. The 6V6 is a beam-power tetrode vacuum tube. 5K grid-stopper resistor, and the negative bias voltage will be on this pin. -2 6V6 or 6L6 Power Tubes. Adjustable Bias Voltage = Adjustable, via Bias Control, up to -130VDC. Instead of Dynaco transformers, Hammond 1608A audio output transformers and a Hammond 272HX power transformer were used. Non-Adjustable Fixed Bias: This category can be the most labour intensive when it comes to setting the correct bias. Keep slowly turning the pot counterclockwise while watching the voltmeter, and you'll start seeing an increase. Sep 22, 2017 #27. The typical output for a cathode-biased, push-pull pair of 6V6's is 12 watts. This bias may be obtained from a self-bias resistor or from a partially fixed-bias The rise in d-c plate and screen currents with power output is. If you bump up the 6V6 to a 6L6, you'll need more bias voltage to keep it from running way too hot. One reader wanted to see how the Broskie auto-bias circuit could be used with power output tubes; above is a more fleshed-out version of the Broskie auto-bias circuit that would work well with a set of power tubes like the 6L6, EL34, KT88 or 2A3—or even a single output tube. There are many other great bias probes/testers in the market, such as : 1)TAD Bias Master 2)Bias King 3)Ruby. Money Back Guarantee Refund in. If you have not been trained to work with high voltage then have an amp technician service your amp. This resistance is in series with the 15 Ohm current sense resistor, making a total of 125 + 15 = 140 Ohms - for both tubes, The bias voltage needed to control the 6B4G's, must be negative with reference to the cathodes of the 6B4G's ( -40 to - 60V or so ) , which means that the cathodes of the cathode follower must returned to a. Used volts (Plate to Cathode Voltage) = volts Volts: Tube Max Design Dissipation = Watts 100% Pa: Class A Fixed Bias: 70% Cool = Class AB Fixed Bias: 50% Cool =. Tube and Bias Info. But I didn't measure grid voltage after the cathode resistor change. It is meant for use in lower power output amps (20W or less) when no power reductionis desired and you would prefer to use the amp's original bias circuit. 6L6 tubes will draw more heater current and can operate at higher plate voltages. It is possible to obtain greater power output and efficiency than that of the Class A amplifier by using a combinational transistor pair called as Push-Pull. The 6V6 develops from zero to 30 volts grid-leak bias, depending on the amplitude of the audio, causing the 807 screen voltage to vary between ten and about 150 volts. It is a 71 silverface and the plate voltage runs 452 or so. 0V, giving plate plus screen current of 18 mA and a 2. > Fender 5E3 Tweed Deluxe / 5E5 Tweed Pro. The negative bias voltage is often designed to be adjustable by way of a bias pot. VOLTAGE READINGS. A hot bias for a 5F6A Bassman would be around -44V DC. In my case the tubes were Tung-Sol 6V6GT at 14 watts nominal/ea, the plate voltage was 421, and I wanted to set it at 65% Idle Dissipation based on a couple recommendations I received. I don't think the plate voltage and bias voltage will be an issue as long as I always use the amp in "Low Power" with the 6V6's. You lost me here. The plate voltage on mine is 400V and the grid bias voltage is about -36 to -37 volts - this is posted up somewhere. Introduction. Components selection : 12AX7 tube from Telefunken. Filament voltage is also controlled. This tester uses regulated power sources for the bias, plate, & screen voltages, as well as modified operating & testing procedures. If the greed is at 0V, the cathode has to be at +2V. That not only includes using them, but putting them in real life working situations. The 6V6 is a beam-power tetrode vacuum tube. New user coupon on orders over US. There are a few minor deviations from the original schematics. Ohm's law says so, and you ain't gonna argue with *that*, are ya? ;-) It'll be pretty low, because you have the bias trimmer set to max neg voltage. I was curious and bought a few plus adapters and tried them in my 1956 fender tweed deluxe and blackface Princeton reverb and quickly went about buying about 100 more as they sound great. A 12 volt fan runs quietly on the 9 volt supply available in this amp. Yellow Jackets YJS Tube Converter 1-Pair - Fixed Bias Amp Power Tube Converters for Fixed-bias Amplifiers with 6L6, EL34, 6550, 7027 or 6V6 Power Tubes $ 118. Bias your GE 6V6GT tubes for 12 watt max diss. What's the difference in tone and feel between the 6L6, EL84, and 6V6 Victoriette amplifier? The main difference. These data obtain for a 5000-ohm load and for a grid bias equal to -12. I did some googling, read that 52 mA was probably what fried the 470 and its cap and the tube and went with a replacement resistor with a value of 1. I then chose an Edcor output transformer that had a UL tap, calculated a resistor for cathode bias, and my preliminary output stage design was done. Mo-Plex is a Classic Throwback to the Mid '60s Black Flag 100 Super Lead with a new twist: if you Don't need all the Steam of 4-EL-34 tubes delivering 100 watts you can run several types of power tubes with Amazing results, for example: Bias ports allow you to get 32 watts using 4-6V6 power tubes, making this amp Club Friendly !. 05" to reflect a total current of 50 mA. good points! plus any amp that blends tubes has to settle on a medium for both types i. bias would be back at our 20-volt starting point and the practical effect wonld be that the current never got a chance to change at all. What bias xx mA for a 6V6 Deluxe Reverb? There's a nice link on WeberVST. Tube Amp Bias Calculator. Tube amp Bias Calculator. Works with EL34, 6L6GC, 6V6, 6550, KT88, KT77, KT66 etc. The second tube is all over the map with readings as low as 19ma and as high as 32ma without any adjustment to the bias trimpot. 80x12 boat jet ski LOAD C 480 12 $59. Hytron 6V6 Vacuum Tube ^^^^^ ***** Tested on our proprietary tester , the E3444. How to Fender Twin Reverb mod for 6V6 tubes. Have to say -18v to -20 volts on the grid relative to ground doesn't sound right - what valves have you got in there. input voltage (1kHz): You can see we get about 12W at the beginning of clipping, and close to 19W at 5% THD. BIAS R=GRID- 165 OHMS 195 OHMS TWIN VOLTAGE AMPLIFIER 6A6, 6N7, TYPE 6V6-G TYPE 6V6-G FOR PUSH -PULL IS 250 VOLTS IS 300 VOLTS 6V6-G'S GAIN RESISTOR WHEN B+ WHEN Ohms 1350 7350 Ohms 1500 Meg ohms Meg o¶lrns o. 6V6 and 3 watts is operating in class A. The output of the plate on each pentode drives a transformer in order to convert high impedance and high voltage to the low impedance and high The control grid voltage, VB, may be biased via a variable or fixed mechanism where fixed is shown in Fig. Basically what you are doing is changing your Deluxe Reverb into a 1x12 version of a Vibroverb. plate voltage is 230vdc. Check and see if you still have your actual plate voltage and your neg bias and 144: Convert EL84 to 6V6 (6. The voltage coming out of the bias pot goes to a junction with two resistors, which sends the right amount of separate negative voltage to the grids of each of the 6V6 power tubes. 6V6-GC Pentode Plate Voltage 315 Volts Grid No. An amp designed for 6L6 can have 6V6 installed, but it would require the power supply altered to feed a lower plate voltage. 95 Fabric Bias Tape Maker 45 PCS Set 6MM 9MM 12MM 18MM 25MM Sewing Quilting Tools. Help with 6v6 bias question Discussion in 'Amps and Cabs' started by charmboy, Feb 16, 2010. JJ 6V6 tubes can also be used in Peters. Overall this tube has a warm and balanced tone with incredible separation and response. No guitarist should ever be without a trusty amplifier to plug in and rock out. Yeah ,the bias range with the KT66 is 54-70 and fairly well matched on each side. At the time Philips had already developed and patented power pentode designs, which were rapidly replacing power triodes due to their greater efficiency. With the new Electro Harmonix tubes installed I adjusted the bias for 27mA, yielding 11. 6V6GT(A)(B)-STR - Modern production valve, STR signifying "Special Test Requirement. Current tube line up October-2019 Carmen Ghia. This will vary from amp to amp. The lower gm makes cathode biasing less appealing and the driver stages need to produce a greater signal voltage for the same power. 53 0 bids + C $111. View details & Buy. Its unique circuitry creates a platform that reveals the true character of the power tubes to a surprising level. The bias voltage takes a couple seconds to "catch up" as you adjust the pot, so be patient while adjusting the bias pot. The first of this family of tubes to be introduced was the 6V6G by Ken-Rad Tube & Lamp Corporation in late 1936, with the availability by December of both Ken-Rad and Raytheon 6V6G tubes announced. The only issue there, is that the 6V6 actually does need somewhat more drive voltage, compared to a 6BQ5. If you are uncertain that you are experienced enough to work on a live high voltage amp, please take your amp to a professional to get it biased. Safe, Accurate, HANDS-FREE plate voltage measurement. This calculator is for a single tube. Filament voltage is also controlled. Now to create the schematic. See warning on 50C5 page) Tube Power Amplifiers: Push-Pull 80W 31LQ6-based; 4X150A-based (for power supply see above) 6AQ5-based. I bought a lot of 24 NOS Russian 6v6's for use in my JTM-18 (fixed bias) with the bias adjustment all the way down they pulled between 7 and 14 watts, if they are as far out as mine were I would suggest going through them and sorting in to close-ish pairs. I have a special octal adapter that allows me to safely check the plate voltage so I can calculate the actual dissipation of the power tubes. You'll need to check with the guys at Dr. Tubes require octal socket and may be mounted in any position. 6V6 SE Ultra Linear Bias Optimization Matt Renaud, April 2016 Introduction One of the main problems encountered in modern vacuum tube design is a great lack of available information. we know the best plate voltage for the 18W is around 345V for the el84's whereas the amps with a good reputation for 6V6's like the champ and tweed deluxe have over 400V on the plates. The plate voltage on mine is 400V and the grid bias voltage is about -36 to -37 volts - this is posted up somewhere. How to use voltage in a sentence. Hot tubes were removed with leather gloves. Following the introduction in July 1936 of the 6L6, the potential of the. This tester uses regulated power sources for the bias, plate, & screen voltages, as well as modified operating & testing procedures. VALVE BIAS Amplifier pdf manual download. The left-hand plate must lose electrons to go positive. These are exactly 6v6gt tubes with a different Loctal base. As the negative grid voltage is adjusted, the bias current will increase or decrease, depending upon the direction the bias voltage is going. No biasing needed for 6V6 tubes because they can only be used in cathode bias position. While "biasing" an amp is the act of adjusting the bias voltage properly in order to set the proper "bias current" thru the output tubes, there's more to it than that. I set mine at 33ma for 6V6 and 38ma for 5881. KT66 24 Watts Max. HI/LO POWER Switch - Changes the voltage on the power amp input stage (Phase Inverter tube) so the amplifier breaks up sooner. January 2018 in Amps. I use RCA nos and have a couple of sets and one set is not quite matched. Output Tube Biasing, An Introduction – Part 2 Posted on 2017/11/15 by Steve Graham in Amplification , Tubes // 5 Comments Divas of the Power Tube World: L to R, NOS GE USA 7581A, NOS Philips Holland EL34 circa 1956, Russian ‘Winged C’ 6550, Russian Genalex KT77, NOS RCA (probably Tung-Sol) 6550. 1 Emerson 1 Motorola ***** Tested on our proprietary tester , the E3444 Triplett/Westmore 501 : It's a Triplett 3444 / Westmore 501 that has been enhanced. No bias supply is shown for the 6V6s. Range F is 0 to 30,000 micromhos, not. Mo-Plex is a Classic Throwback to the Mid '60s Black Flag 100 Super Lead with a new twist: if you Don't need all the Steam of 4-EL-34 tubes delivering 100 watts you can run several types of power tubes with Amazing results, for example: Bias ports allow you to get 32 watts using 4-6V6 power tubes, making this amp Club Friendly !. Usually this will be the cathode of the self-biasing output stage. This device reads cathode current, but not plate voltage. Circa mid 1950's. If the greed is at 0V, the cathode has to be at +2V. Jun 28, 2020 at. This tester uses regulated power sources for the bias, plate, & screen voltages, as well as modified operating & testing procedures. For example, 300V AC to produce output voltage 100-400V or 220V AC to produce output voltage in range from 50- 280V DC. KT66 24 Watts Max. While "biasing" an amp is the act of adjusting the bias voltage properly in order to set the proper "bias current" thru the output tubes, there's more to it than that. DC Balance adjustment – With the dc voltage between the two red test jacks monitored on a 2 VDC meter scale, the DC Balance control is adjusted to produce a. With a pair of JJ 6V6's @ 28ma I'm getting 417V. 2-voltage adjustment (R39), a grid-No. per channel, 8 watts bridged. An amp designed for 6L6 can have 6V6 installed, but it would require the power supply altered to feed a lower plate voltage. Here we see that a 6v6 can be operated at 250V and 49. The operating point of a tube is determined by the voltage at the plate of the tube and the bias current flowing through the tube. Controls: - Gain, Volume, Treble, Mid, Bass, Body (Depth), Presence, and bright switch - Mode switch (lower/higher gain) - Punch switch (gain boost). This calculator is for a single tube. Broskie auto-bias circuit. Bogner says set the bias to 25ma. 6L6GC 23 Watts Max. This tester uses regulated power sources for the bias, plate, & screen voltages, as well as modified operating & testing procedures. The EL34 is a thermionic valve or vacuum tube of the power pentode type. Plate dissipation is the product of plate voltage and plate current: (340V)(37mA) = 12. More seriously the biasing requirements are different and could cause dangerous excess anode currents. Current target = (Nominal Tube Wattage/Plate Voltage) x % Idle Dissipation. This elevates the heaters by referencing a small, stable DC voltage. The result. Tubes require octal socket and may be mounted in any position. Although Fender is best known for their 6L6 tube amp designs, they have had huge success with the Champ, Princeton, and Deluxe tube amps that all use 6V6GT output tubes. In the 60's, tubes were made with tight tolerances for high quality tubes that all had about the same power output. Calculate Plate Dissipation Based On Plate Voltage And Cathode Current Readings. I use RCA nos and have a couple of sets and one set is not quite matched. Includes function of grids, effect of tube capacitance, tube resistance, heat dissipation, bias, miller effect and calculating voltage gain. It's a Triplett 3444 that has been enhanced. The included original instruction manual has a detailed description of tube biasing, as well as listing all of the possible combinations of power tubes you can run in the Renegade – 6L6/5881, EL34/6CA7, E34L, 6550, 6V6, KT66, and KT77, all with the appropriate bias voltage range. 80-12 LRC 6 PR Bias Trailer Tires 4. Coincidentally the bias voltage for the 6V6 and EL34 are in the same range with 400V B+, which made it easy to do. 5 volts the plate current is stated as 45 mA. The second compromise that is required involves the filament voltage choice. Help with 6v6 bias question Discussion in 'Amps and Cabs' started by charmboy, Feb 16, 2010. Tubes are tested in accordance with the manufacturer's specifications; measurements closely align with a laboratory tester built to rigorously measure vacuum tube characteristics. Page 2 of 2 < Prev 1 2. These tubes. 80x12 boat jet ski LOAD C 480 12 $59. Voltage and Bias Heater Cable for 1830A to 15XX/25XX 48″ Technical Specifications. I've still got 3 of the 6V6 amps and I don't have any of the EL84 amps. if using as single ended amplifier as EL34 ,can be use 6L6. BTW: I have a SFDR which I consistently measure at 470v plate voltage. You will see, for example, that 6L6s max out at 500 volts while EL34s can run higher. It is a 71 silverface and the plate voltage runs 452 or so. Z on that and also find out if it's cathode or fixed bias. This is also related to the matching of the valves. A table of component values for the popular 12AX7 in various operating parameters simplifies pre-amplifier stage design. This tester uses regulated power sources for the bias, plate, & screen voltages, as well as modified operating & testing procedures. Tubes are tested in accordance with the manufacturer's specifications; measurements closely align with a laboratory tester built to rigorously measure vacuum tube characteristics. Filament voltage is also controlled. Is plate voltage measured at pin 3 like an EL34 amp? What the wattage of a 6v6 for calculation? (I know EL34's are 25w) And what's the standard discipation % I. I got this idea from katopan (Craig), on the wattkins. Overall this tube has a warm and balanced tone with incredible separation and response. Non-Adjustable Fixed Bias: This category can be the most labour intensive when it comes to setting the correct bias. Tube amp Bias Calculator. 5992 Tube, Beam Power Amplifier, Special 6V6GT, JAN-CEA-5992 TE-8, 5960-264-2995, MFR: Bendix. THe plate voltage with this cold bias should be around 430V according to the schematic. To do this I simply took the design point for a single ended class A stage directly off the 6V6 data sheet. 24 V / Small Control Open Style, Chassis Mount 120 V, 208 V, 347 V or 600 V Pri. Metal type 6L6 and glass octal type 6L6-GC are used in the output stage of audio amplifying equipment, especially units designed to have ample reserve of. In single-ended tube amps one 6V6 output tube can produce about 5 watts of power. Instead of Dynaco transformers, Hammond 1608A audio output transformers and a Hammond 272HX power transformer were used. Buy from our wide selection of 6 Bias now. AnalogMetric. As the bias voltages required for tube circuitry are a great deal higher than that which can be supplied by any of the power supplies found in the EE department laboratories, I had to build my own power supply. I am amazed at how much I like the results. 2 volts, which means the tube is running at a grid bias voltage of -13. Grid bias voltage would have to be changed too. Since 2006 we have offered a single octal bias probe for use with a Multimeter. The last 50UF capacitor was installed on the pot wiper. These are exactly 6v6gt tubes with a different Loctal base. if using as single ended amplifier as EL34 ,can be use 6L6. I was curious and bought a few plus adapters and tried them in my 1956 fender tweed deluxe and blackface Princeton reverb and quickly went about buying about 100 more as they sound great. This bias meter is designed so you do not have to touch. This system of obtaining bias voltage is know as self-biasing since the tube's own screen and plate currents cause the voltage drop, which is used to bias the tube. > can run 6V6, 6F6, etc, so it needs to be fixed bias. Bias electrolytic cap was changed from 25?F/50V to 50?F/70V in AB868. 6 out of 5 stars 26 $16. Below is an example of bias adjustment procedures for the AS-6i (KT88) model. thank you! Product Description 100% Brand New and High Quality Electronic tube amplifier DIY adjustablenegative grid bias power supply board, single-ended and push-pull can be used. based amplifiers. HV power supply requirements performed on Duncan PS Software Simulator II (PSUII) The original power supply schematic I posted now deleted above used a voltage doubler thus the high current capacity of the power transformer HV winding. Heater voltage Vf 6,3 (V) Heater current If 760 (mA) FAX: +381 18 550 806. Bias Calculator. which is a little more than a 12AT7 triode. The Tungsol 6V6 breaks up evenly from low E to high up the Totally Tweed! The preferred OEM tube of '50s-era Fender Tweed Champ and Deluxe amplifiers The Tungsol 6V6 has a geometry designed to safely handle the higher voltages used in guitar amps " plus heavier plate and grid materials. DISCLAIMER: Vacuum tube equipment operates on very high voltages. We know that the cathode voltage is 2. charmboy Member Depending on the plate voltage, you may want to be closer to the low 20's on bias. Tubes are tested in accordance with the manufacturer's specifications; measurements closely align with a laboratory tester built to rigorously measure vacuum tube characteristics. Setup with the KT66: 382 volts B+ at output tube with -43 volts bias. (Converts 6L6, EL34, 6550, 7027, or 6V6 to EL84) The YJS is for amplifiers with fixed bias power tubes. 5 vrms and 111 wp-p at 58vp-p output. Enter plate voltage: Select output tube: EL84: 6v6: 6L6: 7027: KT66/EL34: 6L6GC: kt77: KT88: 6550: KT120: This information is for reference only. 53 0 bids + C $111. NC = No Internal Connection. For example, 300V AC to produce output voltage 100-400V or 220V AC to produce output voltage in range from 50- 280V DC. The first is that the optimum power out is primarily driven by the chosen plate voltage. com to calculate for you. Still, set the mA current as rmconner80 said for an example plate voltage of 425vuse your Weber Bias Rite. Tone not affected. We know that the cathode voltage is 2. Would it hurt my amp to try 6V6's. This is a fixed bias amp and the bias on these tubes is controlled by negative voltage to the control grids of the 4 EL84 output tubes. Keep slowly turning the pot counterclockwise while watching the voltmeter, and you'll start seeing an increase. Line 6 is a music instruments manufacturing company that specializes in guitar amp and effects modeling, and makes guitars, amps, effects pedals, multi effects processors, guitar wireless, vocal wireless, music software, recording interfaces, digital mixers, and personal amplification speakers. I have a special octal adapter that allows me to safely check the plate voltage so I can calculate the actual dissipation of the power tubes. For example, if the line voltage goes up 5%, the unregulated filament voltage goes up 5% to 6. The only 270K resistors I have are. 6V6 Datasheet. I’m biasing the 6L6/6V6 tubes in a Vintage Sound Amp. Bias electrolytic cap was changed from 25?F/50V to 50?F/70V in AB868. 3W in class A, 4. DC bias voltage from reaching the control grids of the EL84s, 4) Giving the control grids of the EL84s their own ground reference resistor for gain control, 5) Giving the EL84 its own cathode-bias (self-bias) circuit to enable it to run safely and squarely in the Class-A range. 6V6GT-STR – A modern production valve, heavy duty, handles higher plate current. Tube values can vary greatly from one amp to the next. Output Pentode Quick reference data • Anode current Ia=48mA • Transcoductance S=11,3mA/V • Amplification µg2g1=19 • Output power Wo=6W Heating Indirect by AC or DC; parallel supply. How to Fender Twin Reverb mod for 6V6 tubes. 6 Bias On Sale. 80x12 boat jet ski LOAD C 480 12 $59. Ohm's law says so, and you ain't gonna argue with *that*, are ya? ;-) It'll be pretty low, because you have the bias trimmer set to max neg voltage. 3x 6AU6 or EF86 mic inputs, 6AU6 mixer, 12AX7 self-balancing floating paraphase PI with unbypassed cathode biasing, 2x KT66 cathode biased PP. Fender Amp Bias and Impedance. This tester uses regulated power sources for the bias, plate, & screen voltages, as well as modified operating & testing procedures. RE: PP 6V6 triode = 15 wpc ???, posted on March 29, 2012 at 06:03:59. Optimization of the 6V6 SE-UL. 5 volts for a pair of 6L6s and 12. signal vs power output for single-ended operation of a 6V6-G. This is a direct measurement of the tube’s gain, but requires an AC signal source, an AC meter, and ability to adjust the operating point for vastly different. He is the author of The Guitar Amp Handbook, The British Amp Invasion, Guitar Effects Pedals, The Fender Telecaster, The Gibson Les Paul, and a dozen other books, in addition to being a regular contributor to several prominent guitar magazines. I have heard some amps that people have used the Yellow Jackets reverrb run JJ 6V6’s without lowering the plate voltage and I think they sound flat and sterile. As I see it the main advantage of the EL84 over the 6V6 is its lower signal drive requirement. Plate voltage DC voltage measured between plate and cathode. Twin Tube Amp Bias Matching Meter 6L6 EL34 KT88 6550. Global bias applies the same voltage to both tubes (such as in a Fender '65 Bandmaster AA763). 5V instead of 6. Since the plate current of the 6V6 contains audio, the 807 screen was bypassed by C2. What does this all mean? Simply that the EL84 will "over-drive" much quicker and sooner than a 6V6 and produce MORE power for a given input (from PI) voltage. Fixed Bias Voltage = -130VDC, 20ma generated by a half-wave rectifier. 6V6 Datasheet. Here's a collection of Bias-modulating "Tremolo" circuits which I use for retro-fitting common class-AB guitar amplifiers, circuits which are mostly based around the high gain 12ax7 dual Triode. Is plate voltage measured at pin 3 like an EL34 amp? What the wattage of a 6v6 for calculation? (I know EL34's are 25w) And what's the standard discipation % I. 7 volts RMS drive voltage, instead of 35 volts, at the same 1 ampere RMS. It is still in use in audio applications, especially electric guitar amplifiers. Nobsound Vacuum Tube Amp Amplifier Plate Bias Current Probe Tester 8 Pin Socket for EL34, KT88, 6L6, 6V6, 5881, 6550, KT66, KT100, KT120, 7027 (CT1-C, Cathode Current) 4. Two 6SK7 will need 0. unless you are willing to sacrifice them for research. We love this combo! You can also sub the 6L6 family along with the EL-34 for more headroom due to the extra beefy Transformers. The main problems that should be dealt with are low power output and efficiency. In the 60's, tubes were made with tight tolerances for high quality tubes that all had about the same power output. Hytron 6V6 Vacuum Tube ^^^^^ ***** Tested on our proprietary tester , the E3444. The YJS is for amps with fixed bias power tubes. These are exactly 6v6gt tubes with a different Loctal base. Some amps use elevated plate voltage on them and may get 25 watts but they don't last long when stressed that much. For general purpose or replacement use in single ended tube output circuits 807, 5881, 6550, Parallel - 6AQ5, 6V6, EL84 bias, plate voltage, operating points. I don't think the plate voltage and bias voltage will be an issue as long as I always use the amp in "Low Power" with the 6V6's. Knowing what voltage your amp applies to the plate would help. Would it hurt my amp to try 6V6's instead of 6L6's The amp is a 1980 Vibrolux Reverb 6L6's power tubes but i have a set of 6V6's nos 50's RCA's that i pulled from a DRRI wich i no longer have. It is unique in the fact that it shows you both the plate current and plate voltage simultaneously and it is completely self-contained with no switches, knobs or batteries. Analog Metric Limited Email: [email protected] Ohm's law says so, and you ain't gonna argue with *that*, are ya? ;-) It'll be pretty low, because you have the bias trimmer set to max neg voltage. Vacuum Tube - 6V6GT, Tung-Sol Reissue - Totally Tweed! The preferred OEM tube of '50s-era Fender Tweed Champ and Deluxe amplifiers The Tungsol 6V6 has a geometry designed to safely handle the higher voltages used in guitar amps " plus heavier plate and grid materials. BIAS-Setup Edition 5 / February 2007 D. Non-Adjustable Fixed Bias: This category can be the most labour intensive when it comes to setting the correct bias. The output stage draws a high current compared to e. 6V6s are designed 14 watts max dissipation according to This. 02 Kohms, and with the voltage drop now at 32. 3v which is of course the 12. Jensen pure silver. Reducing the voltage (i. The cathode biasing method is self-regulating, to an extent, because increases in cathode current create a larger voltage drop across the cathode resistor, which in turn, creates a larger negative grid-to-cathode voltage, which counteracts the increase in current. Don't go too close to the voltage and current ratings of the smallest ones. Tubes are tested in accordance with the manufacturer's specifications; measurements closely align with a laboratory tester built to rigorously measure vacuum tube characteristics. Increasing the current through the tubes will lower the plate voltage a bit. The anodes are connected to the primary winding, the cathodes to ground (circuits 1, 2, and 3), and the middle of the primary to the high-voltage supply. This tester uses regulated power sources for the bias, plate, & screen voltages, as well as modified operating & testing procedures. New user coupon on orders over US. Onto the Egnater RenagadeThis amp has biasing probe points on the back panel with a section in the manual on how to bias the amp yourself using any number of tubesI had always thought that my Renagade sounded sweetChannel 1 has 6V6's to give me a very retro tone and with a Tele gives a very passable Keef Tone and has Twang aplentyChannel 2 has EL34's to give a very Egnater. Bias 2 -20 volts bias- 10ma. What is the bias voltage? I would think 120 ohms cathode resistance for **all four** 6V6s is in order. [Tube Voltage Regulator 6V6 ] Analog Metric www. The 6L6 and 6V6, which are BEAM power tetrodes, produce the characteristic "USA / Fender-ish. Lab-grade tube testers measure transconductance by biasing the tube to a class-A operating point, then applying a small AC voltage to the grid and measuring the AC voltage on the plate. Filament voltage is also controlled. Current target = (Nominal Tube Wattage/Plate Voltage) x % Idle Dissipation. Select your tube type and amp class (Class A, Class AB Low, Class AB, or Class AB High) and enter your Plate Voltage or B+. Metal type 6L6 and glass octal type 6L6-GC are used in the output stage of audio amplifying equipment, especially units designed to have ample reserve of. Filament voltage is also controlled. 3V AC is used to. Jun 28, 2020 at. There are many other great bias probes/testers in the market, such as : 1)TAD Bias Master 2)Bias King 3)Ruby. Page 2 of 2 < Prev 1 2. A pair of 6V6's in class AB will draw way less current compared to larger power tubes like 6L6GB/GC or EL34's. This tester uses regulated power sources for the bias, plate, & screen voltages, as well as modified operating & testing procedures. Buy Telefunken 6V6-TK Black Diamond Series Vacuum Tubes (Matched Pair) featuring Beam-Power Tetrode Tubes, Ideal for Guitar Amps & Hi-Fi Gear, Ideal Replacement for an Original 6V6, Low Power for Small Combo Amps & Heads, Robust Tone & Headroom. Calculate Plate Dissipation Based On Plate Voltage And Cathode Current Readings. 2 Strong Tung Sol 6V6 Vacuum Tubes. As you hit a note the tube calls for more power and negative voltage on the cathode decreases briefly changing the tube's bias. 5K grid-stopper resistor, and the negative bias voltage will be on this pin. At the same time, however, the unregulated bias voltage becomes more negative, biasing the power tubes colder, thus offsetting this effect somewhat. We chose to only stock the 6V6 version because not only do we like it better than the other, but so does Mark at Victoria. Some people bias 6V6's really hot, but I try to stay below 25ma per tube. As for the EL84 thing, I think Stoo was channeling an 18watt circuit when he typed that!. Global bias applies the same voltage to both tubes (such as in a Fender '65 Bandmaster AA763). of EECS Now, say a voltage v 1 across some junction diode results in a current i 1. This runs the tube at full rated plate and screen voltage, and plots the curves at 10 different grid bias levels. better mids and bottom while keeping the smooth top of the classic 6V6's. The output stage draws a high current compared to e. I have heard some amps that people have used the Yellow Jackets reverrb run JJ 6V6’s without lowering the plate voltage and I think they sound flat and sterile. Amps n More: June 24, 2020, 12:33:33 AM : Welcome, Guest Increase the value of the resistor that's in series with the bias diode to reduce the bias voltage until you obtain proper bias. Now multiply this result by the 6V6 plate current to get the power dissipated in Watts by the 6V6's plate. Pricing & History. 2K in the hot rod deluxe which is a little too low. Help with 6v6 bias question Discussion in 'Amps and Cabs' started by charmboy, Feb 16, 2010. This tester uses regulated power sources for the bias, plate, & screen voltages, as well as modified operating & testing procedures. What is the bias voltage? I would think 120 ohms cathode resistance for **all four** 6V6s is in order. There are however plate voltage limitations on the basic 6V6/6V6GT, the basic 6AQ5, and the 6005 of 250v. The voltage coming out of the bias pot goes to a junction with two resistors, which sends the right amount of separate negative voltage to the grids of each of the 6V6 power tubes. 6V6 Max Plate Voltage Cap can is 500V and besides input and bias circuit, they are 630V on the board. Plate voltage DC voltage measured between plate and cathode. Would it hurt my amp to try 6V6's. Then, everything happens all over again, except this time with the 6V6's and to a greater extent. The red or positive test lead is the one you want to touch off to the test point shown in the video and in the pic's below. Here we see that a 6v6 can be operated at 250V and 49. Given below is the tube amp bias calculator to find the bias in ampere or milliampere (mA or A). The JJ6V6 will need more negative grid bias to be biased correctly in the hot rod deluxe, especially as the primary impedance is 4. Clearly the resistor needs to have a larger value in order to get the power dissipation closer to the target value of 9. It also requires somewhat greater plate voltage (but less power wasted in the screens) to produce the same power and occupies more space. Bias your GE 6V6GT tubes for 12 watt max diss. The HT voltage will “pull up” the negative grid voltage, thus increasing the bias current. To hear this very amp, head on over to the sounds page. It is unique in the fact that it shows you both the plate current and plate voltage simultaneously and it is completely self-contained with no switches, knobs or batteries. The tone was similar to the 6K6's, but the lower grid bias voltage allows the 6G6 to be driven further into clipping. It is located in the filter caps “box”. I did some googling, read that 52 mA was probably what fried the 470 and its cap and the tube and went with a replacement resistor with a value of 1. Normally this is achieved via a potentiometer. Put the 7c5 in the adapter and your good to go. 2x 6X4 rectifier. What range should I be looking for? I dont want to put the tubes in and not have enough negative bias voltage. You lost me here. Then, everything happens all over again, except this time with the 6V6's and to a greater extent. Figure 1-25. I still say you're going to be hard pressed to get more than 16 watts from a cathode biased push-pull 6V6 amp--and that's with way-above-spec plate voltage. This bias meter is designed so you do not have to touch. The shield of the 6V6's is connected through a resistor to the anode, so that it has a fraction of the anode voltage. As a convenient example take type 6V6-G for which the following values have been pub- lished in the Data Sheet dated April, 1940 : Plate Dissipation Screen Dissipation a plate voltage of 250 volts. K = Cathode. Filament voltage is also controlled. He is the author of The Guitar Amp Handbook, The British Amp Invasion, Guitar Effects Pedals, The Fender Telecaster, The Gibson Les Paul, and a dozen other books, in addition to being a regular contributor to several prominent guitar magazines. If your calculated bias point happens to be 40mA then adjust the bias current up. Maximum wattage, 2 6V6 in PP, cathode bias Discussion in 'Amp Tech Center' started by jhawk, Sep 20, 2017. This is the best opportunity you will ever have for 7C5 matched tubes. There is a lot of discussion on the black magic of setting the bias on the output valves in your amp. every 6V6 I try in this amp pulls between 48 and 52 mA. This is the best opportunity you will ever have for 7C5 matched tubes. This amplifier does not use a bias pot, instead relying on two resistors acting as a voltage divider in order to establish the bias voltage. 3W in class A, 4. These amps came stock with a GZ34/5AR4 rectifier tube and 6V6 power tubes. Replacing the rectifier tube is a good way to get a different sound from your amp. Circa late 1950's. Sylvania 6V6 GT Vacuum Tube Very Strong ***** Tested on our proprietary tester , the E3444 Triplett/Westmore 501 : It's a Triplett 3444 / Westmore 501 that has been enhanced. 6V6 Datasheet. With this adapter and multimeter it's safe and quick to measure the bias currents of the tube amplifier without opening the amplifier. Increasing the cathode bias resistor is often necessary. Would it hurt my amp to try 6V6's instead of 6L6's The amp is a 1980 Vibrolux Reverb 6L6's power tubes but i have a set of 6V6's nos 50's RCA's that i pulled from a DRRI wich i no longer have. The bias meter is very easy to use: NOTICE: Guitar amplifiers have very high voltages that can cause harm to you. Adjust the bias trimmer ("pot") until you get a reading across the 1-ohm resistor(s) somewhere in the 30-40 mV range, for everything but 6V6s. For years I have been using a valve tester that I had developed in the past. The 6V6 and EL33 are NOT equivalent! A hasty note of warning! They have the same base, connections and heater volts but differ considerably. The result. Limited supply. Don't try 6V6-GT/GTA.