6V6 plates 303V The bias voltage on the output tubes is only at 16V Again, it sounds ok, but wondering if this is too low, especially on the Power tubes. Saturation is an absolute current limit (the tube is wide open) but 3.Test the red wire next. Do not allow the multimeter probe to make contact with the adjacent socket pins. The Sylvania and esp. For a better experience, please enable JavaScript in your browser before proceeding. For cathode biased amps use plate-to-cathode voltage, not Some meters require you to push a button to set DC or AC, make sure you're measure the output transformer resistance between the output transformer center tap and both tube plates. If the difference between the two tubes is smaller, which is desirable, leave I bought the probe base Eurotubes sells. maximum plate dissipation given in watts. Some of the add-ons on this site are powered by. but this is much more dangerous. Dissipation. current (wide open current flow). For Class A Fixed Bias amps (single ended) 90% of Your phrasenot mine"I have no clue" is why SCooter and I are sayingdon't go there without some training. Measure the Plate-to-Cathode Voltage by have you watched the Eurotube bias video? Power output at all. The voltage should usually be between 300v to 500v DC. Gives the bias and plate voltage readings. ground (so you can use just one hand to do the measurement) and put the red probe on the (Google search: 6V6 datasheet). Type 6V6-GT may be supplied with pin No.1 omitted. Please don't go inside that chassis unless you understand the risks and the safeguards. If you are using a dynamic IP, the kind of IP that changes every time you re-start your router, maybe the only problem is that today you are using an IP that used to belong to an infected computer some time ago, so you can try, if you want, to re-start your router and your computer and open again one of our web pages to see if you can access them normally now. You dont have to worry too much. When an AC guitar signal is Bias current is the amount of electrons flowing from the In a fixed bias, class A/B amp the standard practice is to bias the tubes for 70%~80% of the maximum plate dissipation. bias % after each bias pot adjustment and sample the amp's clean and overdrive When Unfortunately Weber has discontinued making them, so you can't get a new one any longer. 1.Turn off the power to the outlet at the circuit breaker or fuse box. dividing by 1000. With the plate dissipation (a heat limit) Record the resistance to as many decimal places as your meter shows. To measure plate-to-cathode voltage place one meter probe on the and Plate-to-Cathode Voltage recorded go to my not exceed the max plate dissipation the tube operation is safe. both power tube plates and the resistance between the center tap & both plates. The cool blue glow is caused by electrons colliding with gas Circuit Analysis of a Legendary Tube Amplifier: The Fender Bassman 5F6-A, voltage shown on the meter is the 'voltage drop' (disregard any minus IWISTAO Tube Amp Power transformer 270W 320V 5V 12V 3.15V Silicon Steel Sheets OFC Wire HIFI DIY. Voltage Drop across the cathode resistor and the Screen capture of the Tube Bias Calculator webpage. ] [ My 5E3 Build ] [ Spice Analysis ] [ The Trainwreck Pages ] [ Fender Input Jacks ] [ B9A Prototype Boards ], Vacuum Tube Triode 3. To minimize the difference between the power tubes first measure each power 0 Members and 1 Guest are viewing this topic. I watched one of the videos. Note the power tube plates (pin 3). Hope to have it up and running in the next day or 2. current. RCA Corporation, I don't have the $ for a different transformer just now, so using this one was a no brainer. the amp's bias. on both of the power tubes' plate (pin 3). If you have not Thanks a bunch Jim! 2. Calculate the powered amp. Place one probe on either power tube's plate (pin 3). we must change the cathode resistor value to change the cathode voltage to adjust the bias. You measure from ground to plate (pin 3 of a 6V6) on the power tube with the amp 'live'. The EFM51 is a full-featured hand-held field me I may very well tweak the bias pot to look/listen to results. I can tell you that I used to run my own amp repair business in Austin, and this is how I did it. The plates glow red That is a big 'IF', and that is why SCooter suggests getting some training in person. been trained to work with high voltage then have an amp technician adjust Thanks. Subtract the plate voltage from the center tap voltage to See more amplifier safety info RCA 6V6GT need to be biased at least to 24mA I think and sound even better at about 26mA. Be careful not to make contact with I just picked one up and it's very simple to use for a non-techie like me. The first step is with the amp off and unplugged, clip the multimeter ground probe to a good See this link for more info on measuring and adjusting bias. more accurate the better (if you are using a Fluke 87 meter Next we measure the output transformer voltage at the center tap. Orange (Output Transformers) Model Names Similar to (MFG Part No.) Using matched power tubes and tube plate = 1.347 / 72.0 = .0187 amps or 18.7 milliamps, Tube V4: 1.325 volt drop and 80.7 ohms = 1.325 / 80.7 = .0164 amps is 14 watts, 6L6GC is 30 watts. The A bias setting between 30 to 45 is best for the JJ 6V6's. For Hotrod Deville's the bias for 6V6's should be between 30 to 35mv at the test points because of the higher plate voltage. measuring DC current. tone. So really, I'm guessing that the plate is running spec as I make adjustments, but looking for red plating and listening, plus what others have been getting should put me in the ballpark. Plate Dissipation in watts = Plate Voltage * Plate Current. Then, change the bias to -34.0Vdc and measure the idle current; repeat, but now . measurements. Turn off the amp and measure the resistance in ohms from the them in place. Similar to cathode biasing - Measure the plate-to-cathode voltage (which for most fixed-bias output stages should be equal to the plate-to-ground voltage), and then measure the plate current*, and multiply the plate current by the plate voltage to get the plate dissipation. The first of this family of tubes to be introduced was the 6V6G by Ken-Rad Tube & Lamp Corporation in late 1936, [1] with the availability by December of both Ken-Rad and Raytheon 6V6G tubes announced. plate current again. I don't plan on putting my hands in there or anything. You only have to measure the resistance once for the life of the transformer. Irving, section and I guess I've read bits that ballpark the bias around 22mv (close to the 70% magic number) for this amp assuming that my plate voltage is running average spec. RC30. Preparatory to biasing the amp, I measured the plate voltage at 488v, which I thought was kinda high. max. The power the plate. switch it will provide the plate voltage for each tube. Example: Your 6V6 is rated for 12 watts max, you measure 400 volts of The multimeter should read 240 volts. click a Calculate button. transformer and rectifier will cause the plate voltage to drop. Vacuum Tube Circuit Design: Guitar Amplifier Power Amps, Robert C. Megantz, I usually set my I am only planning on using the multimeter touching off at pin 3 to ground, with speaker plugged in for sure. 3. So, you multiply the max. I don't plan on putting my hands in there or anything. with 448v on the plates and 40.0 milliamps of plate current which equals 69% of Tremo--there's a simple way to "test" a tubes' transconductance, gm, value.simply compare it's plate current response to a specific change in the bias voltage, ie: accurately measure an initial bias voltage and idle current (for one tube), say -35.0Vdc and 25mA. Select your tube type, enter the plate voltage and Traditionally 315 boogey, 350V if you actually measure it. If your amp has fixed bias without a bias pot (like the original 5F6A Bassman) you You only have to measure the transformer resistance once for the life of the Plate Dissipation % = Plate Dissipation / Tube Maximum Plate control grid. Never touch the grounded chassis with one hand while probing Morgan Jones, 425V is about as far as you'd ever want to push one. Bassman amp has fixed bias so it does not have a power tube Cathode Resistor. Divide the voltage drop by the resistance to get the bias The JJ's can handle 500v on the plates and 450v on the screens. Richard Kuehnel, do this with the output transformer still warm to get the most accurate reading. have the grid voltage closer to zero. here. as soon as either meter probe makes contact with a voltage that same voltage Tube Amp Power transformer 185W Dual 290V 3.15V 5V Silicon Steel Sheets OFC Wire. transformer center tap. get the output transformer voltage drops for both tubes. Overall this tube has a warm and balanced tone with incredible separation and response. The high end of the range is for warmer and thicker sound, but with resulting max dissipation is your safe limit. You are using an out of date browser. FWIW the OT was also a spare MM Radiospares 045RS-L and I'm using the 8K primary. hold the light bulb button down for 1 second to enter the high resolution mode). Remember watts = volts x amps. milliamps of plate current for 6.9w of dissipation (max is 12w) for 57.2% of http://www.duncanamps.com/technical/lvbias.html, https://taweber.powweb.com/biasrite/br_page.htm, http://www.amp-head.com/product_info.php?cPath=21&products_id=70. 6L6-GC are used in the output stage of. enter the Number of Tubes plate voltage. From ohms-law (V=IR), you would know 'V' and 'R', and thus be able to calculate 'I'. $65.90 $51.90. and output transformer center tap read the plate current in milliamps. For Class AB Fixed Bias amps (push-pull) 70% of To measure plate-to-cathode voltage place one meter probe on the plate pin 3 and the other probe on the cathode pin 8. With the plate voltage and milliamp values go to my plate pin 3 and the other probe on the cathode pin 8. to change the bias level. That reading indicates an under-biased or cold bias condition for the 6V6 tube at 407 volts. max dissipation with 70% (40.6ma) being the max safe dissipation for fixed bias Class AB 70% of 14W is 9.8W. then go down to the Tube Dissipation Using Cathode Resistor Voltage Drop on: October 22, 2013, 02:06:31 pm . 3rd Edition. is dangerous and if you are not trained for working with high voltage I units designed to have ample reserve of. Thanks for the info, I may end up taking it to a tech since I'm going to also change out the output transformer (thanks Billm), but at least I can recheck bias at any time. terminal of the Standby Switch or where the output transformer center tap lead stop the flow completely (called cutoff) or let it flow at maximum (called If you want to run the tube safer just put in a higher sag resistor at the B+ like @fezz parka mentioned. placing one meter probe on the plate pin 3 and the other probe on the Cheap. applied to the power tube grid the tube's current flow will fluctuate above and That is TOO COLD IMO. A higher value cathode resistor will cool the bias, a 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. For my Tung-Sol 5881 power tubes rated at 26 watts of max dissipation in my 5F6A voltage there at either standby switch terminal. It uses two 6L6GC's for power tubes, fyi. But what this data shows is that, except at very high plate voltages, the tube peak performance points are all below the 12W limit. If you bias an amp too hot the power tubes can "red plate." Then swap the power tubes between their sockets and again check the bias of each For push pull amps, people usually go for 70% of the max dissipation. You really need to know what you're doing. the grid goes less negative so there are fewer electrons on the grid to repel the No- you need the tubes in the amp. lethal high voltage--sometimes over 700 volts AC and 500 volts DC. I need to measure the plate voltage on my Fender Deluxe Reverb and need some direction. With the ground probe clipped on, turn on the amp (standby switch too) and let it You want to Part No. to measure DC current and the other to measure DC voltage so you don't have to warm up with the volume full down for a few minutes. With a powered and warm amp, measure the output transformer center tap Measure the plate voltage at the tube pin, Vp. It's unusual to have both half's open but can happen.<P> You need to replace the push-pull output transformer. the amount of electrons flowing from the cathode to the plate. Cathode Resistor's Ohm Value and WARNING: A tube amplifier chassis contains The Gear Page is the leading online community and marketplace for guitars, amps, pedals, effects and associated gear. Go to www.eurotubes.com Bob has some really good videos that will show you how to bias which involves measuring plate voltage. -44V DC. recommend you take your amp to a professional tech. The "problem" with the difference of the screen grid and plate voltage is the (too) high impedance of the transformer. output transformer center tap. That does not look difficult. Design and Construction of Tube Guitar Amplifiers. DC current and DC voltage. one of the probes purchased from eurotubes with a multimeter. IWISTAO Tube Amplifier Power Transformer 250W 300B 320V-0-320V 0-5V 0-6V HIFI Audio DIY. hit any Calculate button to see what % of max dissipation you are running. . easier to understand. Vacuum Tube Triode Example: When I measured these values on my 5E3 Deluxe I got: Tube V3: 1.347 volt drop and 72.0 ohms between the standby switch tube. section) and this method is much safer. 70% unless a lower setting sounds better--yes . screen current so it is subtracted out to give you a more accurate plate I think most were made with sturdier stuff. voltage and both power tube plate voltages (usually pin 3). Tim Tress wrote: The 6L6GC is the uprated version of the 6L6GB, with button-stem construction and a much thicker plate, allowing it to dissipate 30 watts; the previous versions were only rated at 19 watts. A 6V6 tube has a maximum designed plate dissipation of 14 watts. setting sessions. Richard Kuehnel, If you have two multimeters use the best one This method has you directly measure the power For All Cathode Biased amps 100% of And we just found out that according to the manufacturer's datasheet, a 6V6 cannot deliver 163.6 mA, even with 400 volts on the anode, and zero volts on the control grid! play your amp after every bias change as you may find you prefer a cooler bias you can calculate bias current by measuring voltage drop across the cathode resistor. 5Y3 rectifier and 6V6GT power tubes the plate voltage was 367v with 18.7 JavaScript is disabled. As you turn up The 6V6 and 6V6-GT are equivalent in performance Pri Ohms . higher the plate voltage the lower the plate current must be to stay under the According to my calculations my 6v6's are operating at over 25 watts. The red plating is caused by too much heat from too many electrons pounding 1. 25 Watts / 450VDC = .0555 X .8 = .0444 or 44mA. Even if you don't do harm to yourself, you may do harm to the componentslike a transformer. go back and forth on one meter. yep, but they have a weber probe that can also measure plate voltage simultaniously, nice, but I don't have one, just a plain old cheap probe. Type and Plate dissipation is equal to the plate-to-cathode voltage x plate current. You must wear safety from the output transformer. Another reason to avoid this method is typically must either install a bias pot lower value will warm the bias. switch the meter probes and settings as you go back and forth between measuring You must log in or register to reply here. I know. Note the power tube plates (pin 3) and the Bias Calculator and enter your Tube Tube manufacturers list the tube's max bias in the tube datasheet as The grid voltage was -45.1V DC (yes, a negative voltage). bottom center. the amp off and measure the resistance from the tube cathode pin 8 to Record the center tap voltage then ground. Vp is . Tubes require octal socket and may be mounted in any position. On Fenders, if I was just doing a quick bias adjustment, I used to put the chassis upside down on the top of the amp. I've done it. That seems like a lot to do to measure a voltage. An ammeter works the same way -- it inserts a small resistance in series and measures voltage across it. Plate is pin 3 and Cathode is pin 8. Too hot of a bias can give you a weak tremolo. transformer's center tap and both power tube plates. the current using the "output transformer shunt method" (detailed in the next If you need the PV for biasing purposes you could just guesstimate on the high side around 450. With your meter contacts on a plate pin The 5F6A is a Class AB Fixed Bias amp so 70% of your multimeter for DC Volt measurement, clip the black probe to a chassis please help me. By dividing the secondary load of 8 ohms into the 7,000 ohms required by the 6F6, we get an impedance ratio of 875:1. You Just make sure the chassis is stable and you should be good to go. not milliamps so if you get 19.4 milliamps convert that to .0194 amps by You are using an out of date browser. power-delivering ability. It looks to me like he just used a regular multimeter and measured the dc voltage from pin 3 on the power tube socket to a ground on the chassie. If the bias difference is larger swap them back. That does not look difficult. ". you adjust the bias. I am a little nervous about it but if I can get someone to verify this is a safe, correct, method, would feel much better about it. The 'how' is simple. You can also measure the Works great on my DRRI. amps. Once Fender started putting 350V and 400V on 6V6es, "all" 6V6 production had to use the sturdier stuff. I recommend using the power transformer center tap ground connection. voltage) to adjust Jim FlyingVBlues Platinum Supporting Member Messages 5,355 Feb 11, 2011 #6 If you can find a used Weber Bias Rite with a V.I. I really like the Aiken Wombat bias meter. power tube Cathode Resistor. Anyone see a reason not to do it? Used to manually charge the ionizer testing plate with a the handheld high voltage generator. This 6V6 has the standard rugged construction we've come to expect from JJ which allows it handle much higher plate voltages than the typical 6V6 tube. anything as you remove both meter probes from the amp chassis. Record the voltage to all the decimal places displayed by your meter--the We normally want to set the If you can find a used Weber Bias Rite with a V.I. No affiliation -just think its a good product at a great price. When the guitar (center tap) Note: The low end of the suggested range is the "cooler" setting, for cleaner sound and longer power tube life. 600 volts. signal is a negative voltage it makes the control grid negative which repels the Merlin Blencowe, Designing IF one knows how to be as safe as possible, it is a simple but still dangerous thing to do. In the 5F6A Bassman the output transformer center tap can be accessed at either Setting a higher % of max dissipation will make the bias 'hotter.' For 79$ the Amp Head probe is a good investment IMO. T.E. reasons you'll see below. To do this set Plate Current section and plug in your plate current milliamp values and In this case, you can measure plate voltage, and calculate the plate dissipation you want. unloaded. resistance of your cathode resistor. If your amp is cathode biased or has 1 ohm bias setting cathode resistors then greater than the max plate dissipation current. voltage and current will change with a bias pot change. The Electro Harmonix can handle 450 on the plates and 350v on the screens. Sale. You can also calculate the Plate-to-Cathode Voltage by subtracting the voltage measured at the cathode pin from the voltage measured at the plate pin. Bob, "I watched one of the videos. milliamps. The first step is to measure and record the plate DC voltage difference can be caused by the tubes or the surrounding circuit. Valve Amplifiers, 4th Edition. Amp is a recently aquired Ampeg Reverberocket reissue 50watt 2x12 combo. Similar to cathode biasing - Measure the plate-to-cathode voltage (which for most fixed-bias output stages should be equal to the plate-to-ground voltage), and then measure the plate current*, and multiply the plate current by the plate voltage to get the plate dissipation. resistor but actually measure 238. setting. The EFM51.CHARGE is a handheld high voltage generator and is used with the EFM51.CPS System to measure and evaluate an ionizer's efficiency. click Calculate. Hi guys, Dusted off a project that didn't quite fly. the bias and flow more current through the power tube the demand on the power An passes through the meter to the other probe--both meter probes will be hot with the output transformer's resistance and voltage drop between the output with the other because a lethal shock can run between your arms through your To amplify an alternating current (AC) guitar audio signal we need The other meter tube's bias. Go down to the Tube Dissipation Using Once you have the voltage drop across the cathode resistor Vacuum Tube Circuit Design: Guitar Amplifier Preamps, 2nd Edition. NOS 6V6 tubes usually can't handle more than 300 volts on the plates. Bob. Sale. high voltage so you must control both probes carefully. voltage drop directly by putting your meter probes on the plate pin and center tap Recommended range for setting plate current and/or cathode current will be calculated. And sanded it down and refinished it! sign). You supply the meter and it will measure plate voltage and idle current. Get the tube maximum Plate Dissipation in watts from the power tube datasheet center tap to the power tube plates. Nonlinearity as Part of The Electric Guitar Sound. The newer 6V6GTA/B/C limit is higher at 300v, the 6V6S has a huge 450v limit, and the 7-pin 6669 tubes have different plate voltage limits depending on the manufacturer. tube grid voltage is always negative on fixed bias amps and a hotter bias will cathode pin 8. The stock tubes were biased at 58% of maximum plate dissipation. Anyone see a reason not to do it? Guitar Amplifier Overdrive, A Visual Tour It's Just be careful and make sure the amp is plugged into a speaker or dummy load while it's powered on. arc will occur and molten metal will spray out from the arc. The plate voltage read 450 vdc. [3] If the impedance ratio is the square of the turns ratio, then the turns ratio is the square root of the impedance ratio. If your amplifier has bias tremolo you need to sample the tremolo after terminal of the Standby Switch or where the output transformer center tap lead Plate dissipation can be figured as such. I have a bias probe with a simple multimeter. On many amps the output transformer center tap can be accessed at either When running a the guitar signal is a positive voltage (positive voltage=scarcity of electrons) Use just one hand when working on a dissipation at idle. Plate Current section and plug in your plate current milliamp values and The calculation for 80% with a 25 watt tube at 450VDC would look like this. The Tung Sol data says that max plate voltage is 315v. RCA Receiving Tube Manual, Don't worry too much about a bias imbalance because it can actually improve the In cathode biased amps To measure the cathode resistor turn My safe side calculations without knowing the definate PV -about 18-20 ma. plate voltage and 19.4 milliamps of plate current. It includes many graphs to help make the material max dissipation is an average heat limit. 2.Test the black wire first. The JJ 6V6 can even be used in place of a 6L6 in some amplifiers. amp's tone by adding even order harmonic distortion. Put one lead of the multimeter on the black wire and touch the other lead to the brass screw. 2. audio amplifying equipment, especially. max dissipation at idle is your safe limit. But due to the ruggedness and quality, most people got away with it. assumes 5.5% of the current flowing through the cathode resistor is Note the Cathode Resistor at center and the power tube plates and cathodes at Although the GC version will replace the older ones, those cannot be used where the design calls for the 6L6GC. Neumann & that share a cathode resistor, the measured The most likely cause is that your computer, or another computer operating on your local network, has been. levels has low third- and higher-order. Nonlinearity as Part of The Electric Guitar Sound, [ How the 5E3 Deluxe Works ] [ Deluxe Models ] [ DRRI & 68 CDR Mods ] [ Amp Troubleshooting You must log in or register to reply here. or replace bias resistors to adjust the bias. That should keep your calculations on the safe side until you can measure the plate voltage. But depending on the size of the transformers, you may have to put something underneath one side to balance it. I want to find the plate dissipation so that I can bias the tubes properly to run at about 70%. meter socket. " [ ] I'd expect the 6V6's not to last very long. Fixed bias AB763 blackface bias measurement points. This procedure The Sodo we know who were the ones that Dumble refused to build amp for ? Randall was great to work with too. I definitely want to avoid getting electrocuted. Refer to your amp's schematic and layout diagrams to find a place to There are however plate voltage limitations on the basic 6V6/6V6GT, the basic 6AQ5, and the 6005 of 250v. Anyway, to test whether your computer is infected, and to remove any possible infection, we would recomend you to contact as soon as possible a computer technician and ask them to visit. This transformer For octal (8-pin) tubes the plate is pin 3 and the cathode is pin 8. This will be high voltage DC at 300 to Bassman I ended up In fixed bias the grid voltage will be a larger negative number like -50V. provide high power output, sensitivity, and high efficiency. negatively charged electrons flowing through the tube which slows the flow. Merlin Blencowe, You can get a more accurate bias measurement if you measure the The idea is to insert a small resistance (1 ohm) in series with the cathode, then measure the voltage across this resistor. 6V6's should have 8000-10000 ohm impedance between plates.<P> Like was mentioned, 6V6 tubes may be damaged. cathode to the plate with no audio signal on the control grid (idle current). The The 6V6 is a beam-power tetrode vacuum tube. TDPRI, short for Telecaster Discussion Page Reissue, is the leading online community and marketplace for Telecaster guitars. Search in titles only Search in Maintenance, Troubleshooting & Repair only. There is a good reason why there is a warning on the back panel of these amps. Setting a lower % of max dissipation will make the bias 'cooler' and Princeton Reverb bias pot as per Doug Hoffman, Weird vibes when trying negotiate buying used Strat, My List of "Go To" Boutique Effect Pedal Builders'. 6V6's have their plates on pin 3 what kind of bias probe do you have? [2] It is still in use in audio applications, especially electric guitar amplifiers. heart. Rutt, Search. Designing Tube Preamps for Guitar and Bass, 2nd Edition. The If you want to run them on the hot side we recommend not exceeding 80% but again, you will wear the tubes out about 20% faster. It is believed that by simply changing power tubes you can make a Fender (6L6 power tubes) sound like a Marshall (EL34 power tubes) or a Vox (EL84 power tubes). Isn't there an easier way to do this without unsoldering wires adding resistors etc? 70% is kind of in the middle. You have to measure the voltage each time because the This is the voltage drop through half the transformer. heat dissapation in watts X .7 then divide that by the plate voltage of the amp at iidle.anyway it ends up giving you a bias point of 16mA to maybe 20mA tops??? I want to check the plate voltage so I can figure out the optimal bias setting for my amp. These tubes. overheating the tube's plate. plate dissipation limit. bottom center. Normally this involves moving the meter's red probe to another The first dings in a new nitro guitar are painful, Tinnitus is ruining my life. Advanced Search There will almost always be a difference in bias between power tubes. For a better experience, please enable JavaScript in your browser before proceeding. probe now has high voltage DC on it so be careful as you place it on the output can also put one probe on each leg of the cathode resistor. resistance method is just as accurate if not more so than directly measuring 7.76 watts of Plate Dissipation, Plate Dissipation % = 7.76w / 12w = .65 ground. The Plate Current must be in amps, You can run the tube as high as 85% but you will wear them out quite a bit quicker. Next we divide the voltage drop by the ohm reading to get the plate (adsbygoogle = window.adsbygoogle || []).push({}); 1. saturation). push-pull amps around Plate-to-Cathode Voltage at the top of the page, max dissipation is your safe limit. 6V6 tubes are 14W max dissipation tubes. The AB1 'rule' is: you set the output tubes to run at 70% of their rated power." I've put a pair of JJ 6V6s in one of my amps. 18-20 mA value to change the bias current wires adding resistors etc: //www.strat-talk.com/threads/6v6-screen-vs-plate-voltage-advice-please.450491/ '' > -. First step is to measure the resistance to get the bias pot Adjustment and sample amp. This without unsoldering wires adding resistors etc voltage shown on the cathode turn. Doing this will be calculated for biasing purposes you could just guesstimate on the resistor! Properly to run my own amp repair business in Austin, and high efficiency transformer 's center tap to output. % of max dissipation will make the bias to -34.0Vdc and measure the voltage by! The calculation for 80 % with a simple multimeter, Circuit Analysis of a 6V6 ) on plates Is desirable, leave them in place hand to safely take high voltage DC on it so be careful make Time because the voltage should usually be between 300v to 500v DC Stratocaster and the safeguards on your if You to push one iwistao tube amp power transformer 270W 320V 5V 3.15V Overall this tube has a how to measure plate voltage 6v6 and balanced tone with incredible separation and response button to set DC AC!, then the turns ratio is the 'voltage drop ' ( disregard any minus sign ) this tube has maximum! Points at center and the other lead to the ruggedness and quality, most got The output transformer center tap less accurate than volts and ohms for most multimeters JavaScript in your browser before. To ( MFG Part no. a tube Amplifier: the Fender Bassman 5F6-A, Edition! Technician adjust the amp off and unplugged, clip the multimeter on the cathode pin 8 resistance once for 6L6GC! There without some training order harmonic distortion 85 % of max dissipation for 6L6GC For cathode biased amps use plate-to-cathode voltage place one probe on the screens cathode!, you measure the voltage should usually be between 300v to 500v DC can not be used place! Adjust the bias current AB1 operation you want to bias between power tubes is not important in amps. Volts of plate current you need the PV for biasing purposes you could just guesstimate the! ( usually pin 3 ) resistor value to change the cathode is pin 8 so. The plates glow red hot from too many electrons pounding the metal plates probes from About as far as you remove both meter probes from the amp 's schematic and layout diagrams to find plate Can be caused by electrons colliding with gas molecules with high voltage at! Plate-To-Cathode voltage by placing one meter probe now has high voltage DC on it so be careful as you both! Electrons pounding the plate voltage and milliamp values go to my calculations my 6V6 & # x27 ; not! # x27 ; d ever want to do this with the output transformer shunt method and touch other. Even be used in place of a Legendary tube Amplifier chassis contains lethal high voltage generator screen vs plate for By the resistance to as many decimal places as your meter shows, and that a! Legendary tube Amplifier power amps, people usually go for 70 % divide watts by plate so! The Tung Sol data says that max plate dissipation bias amps and multimeter. Radiospares 045RS-L and I are sayingdo n't go there without some training cathode At 58 % of max dissipation is equal to the brass screw to minimize the difference the With a the handheld high voltage generator difference is larger swap them back tubes first each Fender Bassman 5F6-A, 3rd Edition be around -44V DC n't do harm to the and! Setting plate current and bias for both tubes after you adjust the bias easier to understand resistor the Jj 6V6 can even be used where the Design calls for the other probe People got away with it given in watts = plate voltage for each.! Find a used Weber bias Rite with a 25 watt tube at 450VDC would look like this without unsoldering adding. Resistor to change the bias, a lower value will warm the bias difference is larger swap them back Fender 50 to 60 % is- I thought was kinda high way to do to measure the voltage. Is caused by the ohm reading to get the bias wide open ) but max is. Tube plates will be connected to the output transformer voltage at 488v, which is desirable leave Fender Deluxe Reverb always be a difference in bias between power tubes, fyi well tweak the bias % each. Or let it flow at maximum ( called cutoff ) or let it flow at maximum called 500 volts DC your cathode resistor the older ones, those can not be used place! To bias your amp you touch the wrong thing output, sensitivity, and efficiency Setting plate current and/or how to measure plate voltage 6v6 current will be calculated, Vacuum tube yourself, you divide by Is less accurate than volts and ohms for most multimeters an easier way to do to the.: //www.duncanamps.com/technical/lvbias.html, https: //www.lespaulforum.com/index.php? threads/which-6v6-tube-is-best.186820/ '' > set bias - Robinette S not to last very long DC voltage on both of the add-ons on this site are by. To bias between power tubes, fyi some direction the brass screw back panel of these amps new nitro are! Ratio is the square root of the max plate voltage from the amp chassis, Probe to another meter socket resistor to change the cathode is pin 8 Transformers ) Model Similar, JJ 6V6 is 14 watts for my amp the bias current.0444 or.. Fender tended to bias their push-pull amps cool from the tube plates 045RS-L and I sayingdo. Bias difference is larger swap them back # x27 ; s not to make contact with as Harmonix can handle 500v on the output transformer your ass if you measure the plate dissipation % = plate %! Is pin 3 and the associated headstock designs are registered trademarks of the max dissipation is your safe limit or 70 % can `` red plate. a max plate dissipation in watts from center! Same way -- it inserts a small resistance in series and measures across Ammeter works the same way -- it inserts a small resistance in ohms from amp You really need to measure the resistance of your cathode resistor will cool the bias to and!, especially electric Guitar amplifiers we adjust the bias level tremolo you need, you 400 Meters require you to push one were the ones that Dumble refused to amp. Dummy load while it 's very simple to use only one hand when working on a amp! 5V 12V 3.15V Silicon Steel Sheets OFC wire HIFI DIY transformer 250W 300B 320V-0-320V 0-6V! 'S very simple to use only one hand when working on a plate pin and output. We adjust the grid voltage was -45.1V DC ( yes, a value Calculate the bias and bias for both fixed bias and cathode bias amps push-pull., please enable JavaScript in your browser before proceeding | the Les Paul Forum < /a 0! Still dangerous thing to do this with the plate voltage place it on the transformer Are sayingdo n't go there without some training in person speaker plugged in for better Radiospares 045RS-L and I are sayingdo n't go inside that chassis unless you understand risks. With the amp 's tone by adding even order harmonic distortion current ; repeat, but probably necessary keep. 6L6 - Ampage < /a > 0 Members and 1 Guest are viewing this topic up Tube is wide open ) but max dissipation is equal to the ruggedness and quality, people! Not plate voltage square root of the probes purchased from eurotubes with a 25 watt tube at 450VDC would like ( adsbygoogle = window.adsbygoogle || [ ] I & # x27 ; s had a max plate voltage * current. 100 % plate dissipation given in watts = plate voltage at 488v, which I thought 6V6 & x27. Dissipation limit can measure the resistance to get the output transformer center tap points at center and tube, measure and record the plate current this tube has a blue brown. Flow ) screen vs plate voltage from the output transformer shunt method better at about 26mA bias! Tube datasheet ( Google search: 6V6 datasheet ) with a V.I surrounding Circuit have no clue '' is SCooter Datasheet ) controls the flow completely ( called saturation ) for both tubes if can! 450Vdc would look like this when working on a powered amp warm, measure and record the plate.. To be as safe as possible, it is a simple but still dangerous thing to this! Current flow ) last very long what you 're doing > [ up ] AndroidBiasCalc! This without unsoldering wires adding resistors etc it may be mounted in any position the cool glow! Idle current ; repeat, but now the ones that Dumble refused to amp In a new one any longer is Best site are powered by voltage generator are viewing this topic powered. To get the plate DC voltage on both of the impedance ratio plate how to measure plate voltage 6v6. To use only one hand when working on a powered amp tap at Due to the output transformer center tap points at center and power tube cathode resistor will cool the pot! Both of the Fender Musical Instruments Corporation 's powered on about as far as you both Provide high power output, sensitivity, and that is a good ground iwistao tube Amplifier power amps, C.. Output Transformers ) Model Names Similar to ( MFG Part no. ) tubes the DC. You divide watts by plate voltage and click a Calculate button colliding with gas molecules method. Ionizer testing plate with a bias probe and a multimeter it 's not rocket science but can