6v6 Plate Voltage

I use RCA nos and have a couple of sets and one set is not quite matched. All we need to do is determine the turns ratio of the transformer, and with that information we can calculate what impedance will be reflected back to the primary with a given load on the secondary. The 6V6 can produce somewhat more power and is generally a long-life tube. 025A x 140 ohms = -3. Since this will change the plate voltage on the 6V6, you may want to adjust the cathode resistor afterwards. Maximum for the 6L6 is up 10. Never owned a 5150 myself though, just Dual Rectifiers And if the OP didn't know, you should measure plate voltage from the OT primary (around 400-450 volts usually). Now you can ballpark calculate your final resistor value which. For the 6V6 tube, find those that are for triode connection. 6L6 tubes will draw more heater current and can operate at higher plate voltages. Terminal Strips; Turrets & Turret Boards; Logos & Faceplates. 6V6's and EL84's require even less. Tubeset for Egnater Tweaker 15 This tube set features our No Rebiasing is needed since the amp runs on a cathode biased If you're modifying your amp, the first thing to do is to get a bias adjustment pot put into your amp, and bias reading jacks on the back or buy a bias tool that has. Octal, IO) K8A, USA 1935 and Power/Output shown. The first two design considerations are the 6922's the plate current and plate voltage. 5V4s are indirectly heated and take longer to conduct which means B+ takes a few more seconds to get going. If you attempt to read the plate voltage with your meter still set up for a current reading, the results will be spectacular (as outlined above. For instance, if the plate current changes by 4 mA when the grid voltage is changed by 2 Volts, the mutual conductance is 4 mA/2 Volts or 2 mA/V. Plate current for each tube can then be calculated from the voltage drop between the OT center tap and plate lead using Ohm's law. The Gillespie driver/paraphase (floating) circuit uses a higher value plate resistor for 12AX7 (actually 6EU7, same thing but 6. I use JJ's but have good transformers so it's ok. Oh, and a 5V4 rather than a 5Y3 should also be considered. This is a hotly biased amp! Here are 6V6 plate characteristic curves for a 0V grid. (*)These specifications are provided 'as-is', with no warranty of any kind. 6L6 tubes will draw more heater current and can operate at higher plate voltages. Press TEST 1 and observe result. Any of the 6V6 USA made tubes I list here should work fine in any amp calling for 6V6 or 7408 outputs. Title: 6L6 Author: RCA Subject: FP-1999-02-28 Created Date: 2/24/2002 7:46:40 PM. The JJ's were put in with a plate voltage of 440 volts and biased at about 80% of their rated output. These tubes are designed to exhibit good headroom, can take a ton of plate voltage, and last. The 6V6s should see about 305VDC at the plates and SGs, so their B+ should be 310-315VDC, depending on the DCR of the OPT primary. The 150 volts is rather high with 220uF I would use on the voltage doubler capacitors vs the 22uF shown that does require 150 volts. 5mA and plate voltage is 250V. Fender Champion 600 Output Transformer Another difference between the new Fender Champion 600 and the older Fender Champ 5E1 and 5F1 circuits is the higher supply voltage (also called the B+ voltage) and an accompanying higher impedance primary on the output transformer in the Champion 600. That dropped the plate voltage down to 170-173 volts, with cathode voltage at 1. Calculate Plate Dissipation Based On Plate Voltage And Cathode Current Readings. That should help with noise I would think. Vacuum tubes for your guitar amp from Electro Harmonix, Sovtek & Tung-Sol. 01 mF) to the network were to fail, high-voltage DC would be applied to the transmission line, antenna, and the various plate circuit components. This will primarily be a home practice amp and I ordered it as a class A single 6V6 6 watt RMS amp in the same finish as my Encore. 2 DC (screen) dissipation 2. It also requires somewhat greater plate voltage (but less power wasted in the screens) to produce the same power and occupies more space. Except for their robust and forgiving heater filaments, it is very difficult, bordering on impossible, to blow out a tube with overvoltage; whereas, most transistors can be destroyed with as little as six volts, and every transistor can be destroyed by some voltage. You could make a choice based on cost or availability and loose nothing to quality in this group. If a shared cathode resistor is used, as is in this 6V6 design, with 250 ohms with each channel, it is best to use matched (or at least fairly close) pairs for each channel. The 6V6 is dissipating about (352-26)*(26/470 -. "Install 6V6 tubes in my Fender 6L6 amp" This is an often asked for mod that I won't do in any case. Maximum signal power output for the 6V6 is about 5 watts. If the input capacitor (0. Re: 6V6 Red plates on Princeton Reverb clone. The bias is a NEGATIVE voltage applied to the control grid of each valve. Obviously you can run more idle current with 300 volts on a 6V6 than 400. The schematic shows the output transformers' primary impedance to be 8,500-Ohms(plate-to-plate) (Zoo), so the tube impedance is something LESS than 2,125-Ohms (Zo), assume 2,000-Ohms (Zo'). Grid bias voltage would have to be changed too. Plate dissipation is the product of plate voltage and plate current: (340V)(37mA) = 12. Guitar amps usually sound best when the quiescent load line passes slightly below the knee of the curves. Some comment that 340V HT is too high, but ignore that for now. 6 volts to ground. Big difference. The plate and UL connections to the OPT can remain as-is, the 470 ohm resistors can be 1 watt, 3W isn't really needed. The 6V6 and 6V6-GT are equivalent in performance. Any of the 6V6 USA made tubes I list here should work fine in any amp calling for 6V6 or 7408 outputs. You should always avoid having more than 430 volts across a 6V6 (plate voltage minus cathode voltage). That dropped the plate voltage down to 170-173 volts, with cathode voltage at 1. The green curve is an eyeball estimate for a 300V screen. Electro-Harmonix 6V6 EH Vacuum Tube Sweet, singing tone for high plate voltage amps. Cathode voltage means the voltage across the 250 ohm cathode resistor. For the voltage we must subtract the voltage (see schematic) on the cathode, 28 volts, from the voltage on the plate, 375 volts = 347 volts. The voltage at the bottom of the 16uF filter cap is 421VDC right out of the 5Y3. This page is primarily concerned with a method of plate-modulating a class-C RF stage without the usual modulation transformer. the inverse of the output transformer impedance as the gradient, , and; the intercept calculated by ; giving. Bias depending on plate voltage at 50%-70% of plate dissipation as a starting point. TYPICAL OPERATION CLASS A SINGLE ENDED OPERATION Plate Volts - 180V Plate Current - 30MA MAX Screen Volts - 180V Screen Current - 4MA MAX Plate Load Resistance - 5500 OHMS Power Output - 2 WATTS Plate Volts - 250V Plate Current - 47MA MAX Screen Volts - 250V Screen Current - 7MA MAX Plate Load Resistance - 5000 OHMS. Find the graph that plots the plate current against the plate voltage labeled average plate characteristics. The first thing to notice here is that the distortion does not seem to vary by plate voltage. The most common way I have done this is to place experimentaly 2 100 ohm 5 watt wirewound resistors in the HT transformer secondary. Read our reviews or we'll help you with a recommendation. - You can use anything from +500 VDC to +800 VDC for the high B+ supply. Tubes require octal socket and may be mounted in any position. An amp designed for 6L6 can have 6V6 installed, but it would require the power supply altered to feed a lower plate voltage. The plate voltage with them I measured is 435V ! The question now is, can I put those NOS tubes in that Deluxe Reverb? Will they blow? I read somewhere that for some old NOS 6V6 tube the max. 5mA and the plate voltage of 250V. The plate voltage is fine! However,if you want to try 6V6`s in a Rocker 30, you need to run them into an 8K load! The Rocker 30 has a 4K load which will become an 8K load if you use the 8 ohm jack to run a 16 ohm speaker! This amp also has 2 cathode bias resistors, one 270 ohm and one 330 ohm, wired in parallel. All Preamp Tubes are Cathode Biased. 1K Control voltage 47u 400V 1u 1M 10K 5W EL84 2 7 1 5 4 3 EL34 6L6 6V6 8 0. The principal advantage of Heising. Plate voltage DC voltage measured between plate and cathode. New Duncan Munro Vacuum Tube Models. Plate dissipation is the product of plate voltage and plate current: (340V)(37mA) = 12. The NOS GE 6V6 and the current-production EH 6V6 are essentially the same in power draw. The JJ 6V6-S is an interesting case-it draws more heater current, but not as much as the 5881, yet its plate structure is almost as large as the 5881. A cathode follower driver stabilizes the a-f signal voltage, but does not stabilize the grid bias. Custom finishes available upon request. After flipping the amp off standby there was some low volume crackling which sounded like insulation breakdown, so I shut the amp off and pulled them out. Back to agenda New Positive Plate for Application of the UltraBatteryTM in Low-Voltage Hybrids. I'm liking this amp more now that I'm getting to grips with it. Current goes up voltage goes down. That dropped the plate voltage down to 170-173 volts, with cathode voltage at 1. Plate voltage is measured right at the plate of an operating and idling tube, with respect to ground. But leave them alone so you can pop in EL34's if you want. This was done at the request of an amateur who had recently built a power supply with 135 volts out at 50ma. 6L6's and 6550's require around 50 volts of bias. 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. Less tolerant of overloads and voltage spikes than tubes. Now we can estimate how much signal "drive" voltage (Vg) the phase inverter circuit must deliver to the grids of the 6V6 output tubes for them to produce. The only new manufacture tube that I'm aware of that can handle this amp and other 2 6V6 Fenders reliably is the Ruby 6V6GTBC. As a very general guideline, an EL84 is a 12 watt tube, a 6V6 is a 14 watt tube, an EL34 is a 25 watt tube (except the GT E34LS is a 30 watter and not to be confused. The BiasPro will not work for you. From the graph, the red dot is the picked operation point, you can see the grid voltage is at -1V, plate voltage is about 130V, plate. The first thing to notice here is that the distortion does not seem to vary by plate voltage. My question for the group is has anyone tried using the 4CX800A at these higher voltages with any success?. Most all amps will show zero plate current until switched out of standby to the play mode. Chances are, yours will, all other things being equal, and assuming your bias is set to the B+ voltage and not just some generic spec that was used for the "average" amp at the factory. This would kill many 6V6 tubes (and had in the past). Lastly, we have the Electro-Harmonix 6V6GT tube which is great for high plate voltage amplifiers like the Fender Deluxe Reverb and it is made in Russia. 9 amp for the 6L6. The bias is a NEGATIVE voltage applied to the control grid of each valve. and a little less strong bass. The TAD and JJs are rough and can take a lot of beating. 6V6's and EL84's require even less. Other than little amps (single 6V6 and EL84 amps) almost without exception Power Tubes are Grid Biased. subtract the cathode resistor voltage drop from the plate voltage and work out the idle current to achieve that 70 % figure. 2 DC (screen) dissipation 2. Current = Constant * Cathode Area * Plate Voltage 3/2 / Distance Between Electrodes 2. If you know what you are doing and can measure the voltage on pin 5 of the output valve to ground (the control grid) then it should be a negative voltage of around 30-40V. NOS/NIB Power Tubes. 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. Now, 1A/1V is the unit of conductance and is defined as a reciprocal ohm or "mho", since ohm spelled backwards is "mho". If the tube can handle 400 Plate volts, then in this amp it has to be at the limit, pushing it IMO. But due to the ruggedness and quality, most people got away with it. This would kill many 6V6 tubes (and had in the past). Ok vintage/NOS tube gurus, *which* 6v6 for Fender Vibro Champ? I have always been a fan of RCA black or gray plates. Now you can ballpark calculate your final resistor value which. The original Magnavox circuit for 164BA has two 100 ohm resistors forming a virtual CT/divider, and the voltage is taken from the center-tap and applied at the cathodes of 6V6. As the 6AQ5 is a higher power tube than the 6AK6, the power supply in this version is in the more traditional configuration of supplying the output stage plates first, at higher voltage than the pre-amp. In pure A class, the best cathode resistor's value seems to be 450 Ohms (400V on the plates, 29,3V on the cathodes). Type 6V6-GT may be supplied with pin No. How to Cure Red plating. Most post-war radios used a 6V6 in a single-ended output stage. I did plug a pair briefly into a 6V6GT version of an 18 watt superlite that has 340 volts on the plate. Unlike the 6V6 which showed distinct distortion variations by plate voltage, the 6L6 seems to not exhibit such a dependancy. Often times all that is available is a data. Current = Constant * Cathode Area * Plate Voltage 3/2 / Distance Between Electrodes 2. The principal advantage of Heising. TRANSFER CHARACTE ICS 6V6 s Vg(V) 6V6 HISTORY la(mA) 160 140 120 100 PLATE CHARACTERISTICS 6V6 s 100 200 300 400 500 va(V) The TELEFUNKEN Elektroakustik 6V6-TK is newly manufactured and cryogenically treated rendition of the legendary 6V6. The voltage at the bottom of the 16uF filter cap is 421VDC right out of the 5Y3. Then you could expect around. After checking the tubes and replacing the electrolytic in the. The first thing to notice here is that the distortion does not seem to vary by plate voltage. BrainStock video production Our DIY amp, studio, gear blog. Plate voltage definition is - the constant component of the potential difference between plate and cathode in an electron tube. You should always avoid having more than 430 volts across a 6V6 (plate voltage minus cathode voltage). As the plate current is varied by the applied grid-cathode voltage, the voltage across the resistor changes in proportion. This will primarily be a home practice amp and I ordered it as a class A single 6V6 6 watt RMS amp in the same finish as my Encore. Rectifier: 6z5p. The 7189 and 7189-A tubes have maximum plate voltages of 450 Volts DC. Revisiting a homebrew audio amplifier Some years ago, as a teenager of 15, I decided to homebrew an audio amp I had seen in an article in a 1958 Radio-TV Experimenter magazine. 5mA and the plate voltage of 250V. The designs I have seen list the HT at 320~340V. According to my RCA tube book that's falling apart at the seams, literally. 6L6 tubes will draw more heater current and can operate at higher plate voltages. Some 6V6 tubes are better than others in handling higher voltages. Unless you take the plate voltage into consideration, a current specification is meaningless. HM = Heater Tap. It appears for RCA and Tung-Sol, the only difference between the GT and GTA is the heater warm up time. I am using General Electric's 6V6 data sheet for this example. Now you can ballpark calculate your final resistor value which. Detailed Information Yellow Jackets ® tube converters allow EL84 power tubes to be used in place of the most common guitar amp power tubes, including 6L6, EL34, 6V6, 7027, 6550, and 7591. This means that if we use the 6BQ5, our power supply may be reduced in size and the voltage amplifier stages preceding the power amplifier stage may be simplified. I use the normal OT secondary setting for 6V6 and double for EL34 (i. Octal base, beam power tetrode. Tubeset for Egnater Tweaker 15 This tube set features our No Rebiasing is needed since the amp runs on a cathode biased If you're modifying your amp, the first thing to do is to get a bias adjustment pot put into your amp, and bias reading jacks on the back or buy a bias tool that has. Like the EH 6V6, it can withstand higher plate voltages making it a great choice in many tube amps. I thought that perhaps my lower plate voltage (290 VDC) may have been the cause until I realized that the two tuning lamps, although fun to watch, were likely sucking-up valuable RF. Title: 6L6 Author: RCA Subject: FP-1999-02-28 Created Date: 2/24/2002 7:46:40 PM. So if I increase R10, I can see it will have an effect there too and probably preamp voltage would fall too low. Maximum for the 6L6 is up 10. plate voltage. Just use good 6V6GT's and the voltage is not a problem. Z 6V6 quad amps. 6 Bold designators are close or identical, Italic designators are different ratings, different pinouts or different filament voltages. After checking the tubes and replacing the electrolytic in the. The purpose of the voltage regulator tubes in the circuit is not strictly shunt regulation of the voltage feeding the driver and cathode follower tubes. The schematic shows the output transformers' primary impedance to be 8,500-Ohms(plate-to-plate) (Zoo), so the tube impedance is something LESS than 2,125-Ohms (Zo), assume 2,000-Ohms (Zo'). In most AB1 push pull amps, the Screen voltage is is very close to the same value as the plate voltage, most tube failure is due to exceeding screen voltage and current ratings. When I learned that TAD released their version, designed to be reminiscent of the old RCA and GE but built to handle modern power supply and high plate voltage, I had to try them. 6*3=26V, giving our stage a voltage gain of 26. Electro-Harmonix 6V6 EH Vacuum Tube Sweet, singing tone for high plate voltage amps. An amplification factor of 70 which classifies it as high mu double triode. The main reason I was suggesting ways to get you as close to 330V as possible was to avoid having to change other aspects of the circuit -- note that because the 6SL7's plate supply is fed from the ultra-linear tap in the schematic you posted, any increase in 6V6 plate voltage is going to directly result in an increase in 6SL7 plate voltage. The output stage. plate dissipation is only 12W instead of 14W. I used a variable power supply to find a happy medium for the three tubes. the constant component of the potential difference between plate and cathode in an electron tube…. 20 ma is a little cold. Eaton Jdc3250f. In fact, with the upgraded Beast power supply it was hard to find a distinct difference between the 6AQ5, 6V6, and 6L6. It?s change in character when tested in pentode and also in triode modes, was very slight. The first preamp tube was a 12au7 which I replaced with a 12ax7 to boost gain. 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. (Actual Plate Voltage) Example: Octal - pins 3 and 8 9 pin - pins 7 and 3. Be aware the term plate voltage can have two meanings. It "bends" the specs by 10 to 30 volts, operating the tubes with a tube (plate to cathode) voltage of 310 to 330 volts. e, run more like a 6v6). From the graph, the red dot is the picked operation point, you can see the grid voltage is at -1V, plate voltage is about 130V, plate. THIS IS NOT A COMMON PUSH-PULL! - very low feedback only 16dB - low distortion near to 0. Re: Which 6V6 Tube Is Best? Originally Posted by tweedguy The suffix may indicate glass changes but can also indicate internal operating changesFor example, difference between 6L6G (lower plate voltage max) and 6L6GC (higher plate voltage max)also suffix like GT can correlate slope shoulder glass etc. New Plate Current Matched Pair of JJ 6V6 (6V6GT) Vacuum Tubes. But due to the ruggedness and quality, most people got away with it. Class T Modulator An Experimental Method of Plate Modulating 90 Watts Input to the Final with a Single 807 DALE HILEMAN, W0MCB 1022 9th Street NW, Cedar Rapids, Iowa One of the simplest (although least used) means for obtaining high-level plate modulation is the class A Heising, or choke-coupled modu­ lator. Just 1 volt difference in the bias voltage can make a difference of 10 or even more ma, of anode current. The bias voltage is set low to allow for early breakup, and the screen voltage is filtered for added noise reduction. When a negative voltage is applied to the cathode and a sufficient positive voltage is applied to the plate, current flow will occur as electrons, loosened from their atomic bond, are drawn off the cathode, across the small space between the operational elements, and onto the plate to complete the circuit. plate voltage is 350V. The maximum plate voltage for the 4CX800A is 2. I also read about typical Champs with bigger PTs running 350v-400v on the 6V6 plate, using a similar 470r cathode resistor. Most Yellow Jackets ® provide a substantial output power reduction and a "self-bias" Class A configuration for the EL84 so that no bias adjustment is required. So, at higher plate volts you need a tube that can handle momentary high current, during transients and bass runs --- and not overload and distort. RCAs about the only 6v6 I can use without red plating. Tubes require octal socket and may be mounted in any position. DC voltage measured between plate and cathode. But the voltages still seem somewhat high. OT primary impedance) does not cause the 6V6 to exceed the max. welcome to the enginerd diy tube amp blog- a website dedicated to the do-it-yourself amp builder using a cost-effective approach to building vacuum tube guitar amps browse by topic on the. Metal type 6V6 and glass octal type 6V6-GT are used as output amplifiers in automobile, battery- operated, and other receivers in which reduced plate-current drain is desirable. The OT used in this amp was 6600 60W. That dropped the plate voltage down to 170-173 volts, with cathode voltage at 1. Tube Amp Power Transformer Current Draw Calculator JavaScript must be enabled in order for the calculations to work. Ip is the plate current. After checking the tubes and replacing the electrolytic in the. The YJUni is shorter than standard Yellow Jackets®. I'm looking to build a 6V6 SE guitar amp and will be grateful for your advice. 6AQ5, 6V6, 6L6, 807, 5881, 6550, EL84 1638SEA 211, 845 - Note: The above examples of possible combinations are to help you narrow down the choices of transformers for your favorite tube types. If they are biased incorrectly or if there is a fault in one of the biasing components, it can cause a number of power supply and output section problems. Let's do a comparison of class A on a pair of EL34's and class B on the same pair of valves. I know that many sources for biasing information just specify plate (or cathode) current settings; telling you to bias your 6L6s at "35 milliamps" is nonsense. 5V grid line and the 1. WARNING: A tube amplifier chassis contains lethal high voltage--sometimes over 700 volts AC and 500 volts DC. Plate voltage can be tested using octal test socket in socket #29, positive lead of Fluke to Pin 3, Neg lead to Pin 8. Let's do a comparison of class A on a pair of EL34's and class B on the same pair of valves. The plate voltage not-keyed is about 430v; keyed it is about 420v. 6v6, 6v6gt /g ,- , 6v6gt /g 7ac g-7ac bottom views the tung-sol 6v6 ano 6v6gt /g are beam power amplifiers, designed for , watts watts typical operating conditions and characteristics single tube class al amplifier plate , 10 14 watts j 6v6, 6v6gt /g plate. This tube is OEM in most currently produced amplifiers that require a 6V6. 300B 2A3 101D EL34 KT88 6L6 6V6 Bias Current Plate Voltage Tester Vacuum Tube B3 0. Now multiply this result by the 6V6 plate current to get the power dissipated in Watts by the 6V6's plate. The author cames no responsibility for any information provided. THIS IS NOT A COMMON PUSH-PULL! - very low feedback only 16dB - low distortion near to 0. B iasing by negative grid voltage is highly inaccurate because the same grid voltage can produce drastically different plate currents in different tubes of the same type. Please be aware of that using gz34 or diode rectifier will wear you 6v6 power tubes faster than with a 5u4gb due to the higher plate voltage. This means that if we use the 6BQ5, our power supply may be reduced in size and the voltage amplifier stages preceding the power amplifier stage may be simplified. Some 6V6 tubes are better than others in handling higher voltages. Because the plate dissipation equals the (individual) plate current x the plate to cathode voltage. 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. Because of the contrast control having an influence over the 6V6 plate voltage, and that the 5BP1 has the cathode internally connected to one side of the heater which is earthed, the 6V6 is now AC coupled to the 5BP1. Real 6v6's(that can take the current)are hard to find these days as JJ"s and others label a small 6L6(5881)as a 6v6v. Since the 1k grid resistor stays the same,you can alter. 6 - 6V6 plate dissipation: First, subtract the 6V6 cathode voltage (I-D) from the 6V6 plate voltage (V2/pin3-D) to get the voltage between the plate and cathode. Except for their robust and forgiving heater filaments, it is very difficult, bordering on impossible, to blow out a tube with overvoltage; whereas, most transistors can be destroyed with as little as six volts, and every transistor can be destroyed by some voltage. 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. For the triode data, Supply Voltage is just that, NOT plate voltage. The voltage needs to be reduced such that you don't exceed the 250 vdc plate voltage for the 6AQ5 (note that the 6V6 maximum plate rating is 350 volts. 5w plate dissipation. Because higher plate voltages tend to decrease the plate resistance1, the ‘proper’ bias voltage for a 6L6 (or any output tube) will be different for various plate voltages. WIRING SIDE OF SOCKET IS SHOWN. A cathode follower driver stabilizes the a-f signal voltage, but does not stabilize the grid bias. The bias voltage was -46VDC, and the measured plate current was 12mA, with a plate voltage of 448VDC when measured with a Fluke 112, and 455VDC when measured with an ‘average’ DMM purchased at Radio Shack. I just found my notes from original build; the 6V6 has 315v on the plate, 18. THIS IS NOT A COMMON PUSH-PULL! - very low feedback only 16dB - low distortion near to 0. How to Bias a Tube Amplifier. Shop with confidence. It took a great deal of experimentation, but the Son of Yeti rocks (and much more). 1 kV unloaded and 2. Line Isolation & Autotransformers, safely run equipment almost anywhere in the world! Great for the bench & check out our slight step down units to keep the stress off. The highs are clear and responsive with warm mids and tight solid lows. Grid bias voltage would have to be changed too. 7v drop across a 130ohm bias resistor which I reckon is about 93. Shop with confidence. There are however plate voltage limitations on the basic 6V6/6V6GT, the basic 6AQ5, and the 6005 of 250v. Terminal Strips; Turrets & Turret Boards; Logos & Faceplates. Find great deals on eBay for tube bias tester and tube bias meter. TAD 1-Watt Tube Adapter. So measure voltage first at the plate and then measure your voltage drop at the testpoint convert the voltage at the test point to current by dividing the voltage drop by the resistors value take that current in mA and divide it by plate voltage and arrive at your actual idle tube dissipation, compare this to the tubes published specifications. But, EL84's can only take a maximum of 300 Volts. plate dissipation is only 12W instead of 14W. Most 6V6 and 6L6 tubes bought as a matched pair for guitar amps seem to easily give thumpless operation. I think, I could take same approach with other amps if I would know which is the "standard" plate voltage expected at "standard" mains power, and, what's the maximum dissipation power of plate and grid of each related tube (6V6, 6L6, EL34, EL84, etc). 6W, slightly above the maximum rating of a 6V6. Large ceramic tubes use zirconium getters. The 6AQ5 is a lower power 6V6 in a 7 pin package used originally in car radios, and the 6L6 is an upgraded 6V6 with higher voltage and higher current. alligator clip it to the chassis. Chinese 12AX7B "Silver Dragon" is the favorite amongst metal musicians. If you look at plate voltages in a Twin Reverb vs. This is really quite low compared to many of the Deluxe Reverbs I've worked on. Otherwise, use 500 ohms and bypass cap for each 6V6. So with KT120 tubes, I see about 450v plate to cathode and 25. After checking the tubes and replacing the electrolytic in the. While still a 7-pin miniature tube, it's basically a 6V6 in a small package, so it's got that classic Fender Champ sound. The pentode consists of an evacuated glass envelope containing five electrodes in this order: a cathode heated by a filament, a control grid, a screen grid, a suppressor grid, and a plate ( anode ). 6V6's should have 8000-10000 ohm impedance between plates. So the grid voltage is at -20 VDC relative to the cathode voltage. Let's do a comparison of class A on a pair of EL34's and class B on the same pair of valves. More dynamics. 6 divided by the plate voltage for 70% dissipation - if your plates are up around 500V you're gonna be looking for around 39mV - whether your bias has enough juice to get you there is to be seen - I'm willing to bet it's gonna be a close race the grid's gonna be up around. Brimar 6V6GTYs (Back to review index) Mike, Just a brief note to let you know how much I'm enjoying the pair of Brimar 6V6's you sent me. If using a 5U4 amp, a 5AR4 would be great if subbing in 6L6GCs. The figure below is a plot of the static plate. My existing power supply voltage is 3. Also the max. It is a slightly higher power tube than a 6V6 and the plate voltage is rated at 350 vs. While still a 7-pin miniature tube, it's basically a 6V6 in a small package, so it's got that classic Fender Champ sound. The voltage needs to be reduced such that you don't exceed the 250 vdc plate voltage for the 6AQ5 (note that the 6V6 maximum plate rating is 350 volts. Contact Information. 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. A couple of new PreBS T5 builds are completed and available for sale now! A traditional 8″ version with Alligator Tolex and a custom Black 10″ version with a special Mercury Magnetics OT and 6V6/6L6 switch to maintain proper bias when switching tubes. A failed biasing component that lets the grid assume the same voltage as the cathode will cause an output tube to act almost shorted. 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 reading of close to 0 VDC. Output Tube Biasing, An Introduction. Guitar amps usually sound best when the quiescent load line passes slightly below the knee of the curves. 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. (*)These specifications are provided 'as-is', with no warranty of any kind. When the audio waveform drives Pin 5 of the 6V6 more negative, the plate of the 6AG7 goes more positive. plate voltage is 350V. I read somewhere that for some old NOS 6V6 tube the max. I have not experienced any problems with the higher plate voltages and the Electro Harmonix 6V6 tubes. The 6V6 can produce somewhat more power and is generally a long-life tube. Call: 703-673-8265. Sounds great. BrainStock video production Our DIY amp, studio, gear blog. On the common octal tubes, this can be measured with a voltmeter between pins 3 and 8. Thus, the triode functions as an amplifier of the incoming AC signal (taking high-voltage, high-current DC power supplied from the large DC source on the right and "throttling" it by. Guitar amps usually sound best when the quiescent load line passes slightly below the knee of the curves. Without plate voltage the screen will draw too much current. By Rob Robinette. I considered analog moving coil meters, but reading accuracy is limited and range switching is required to cover a wider range of voltage and current. 1 kV unloaded and 2. The design is no more complex than a traditional high fidelity tube type modulator using a modulation transformer. If you use tubes that require less bias voltage, it's like having extra gain. 00-We have a large stock of these tubes. This allows the plate voltage to drop dramatically, typically down to 25v, while still having the same current flowing.