6v6 Screen Grid Voltage

Voltages were not regulated; plate voltage was 600 V, screen was about 250 V. A capacitor from the arm to ground is still valid for noise reduction. When you turn on your tube amp, the tube filament at the center of the bottle receives a voltage (usually 6. It is biased at a very low voltage: either ground potential, or it is internally tied to the cathode (i. 5 volts by choosing a cathode resistor that will give us a voltage drop of 12. This was caused by secondary emission from the plate back to the screen-grid. The exception in this design is the cathode resistors on the 6V6 tubes (1W) and the voltage dropping resistor 350Ω, 5W in the power supply. Below is the screenshot of specifications from Sony: You can see that the power consumption is relatively lower ranging between 82 ~. The grid-stopper resistors prevent ultra-high-frequency oscillations. Another option is to use a small value dropping resistor right before the screen filter cap to keep screen voltage lower than plate voltage. 89) Posted by jeff mai on 2002-04-02, 16:44:27 (203. It usually is – in particular with high gain power pentodes/tetrodes. The -16V grid curve currently crosses the load line at Ia = 125mA. transforemr is at least need 10(20Hz) to 100Khz(80Kz) bandwith. Also a screen-dropping resistor and bypass capacitor if the supply voltage was over 300. The Gm ( transconductance ) is the difference between the lk1 and lk2 currents, expressed in mA / V, or in uS, or in umhos, by multiplying the value by 1000 : 1mA/V = 1000 uS = 1000 umhos. The rapidly advancing tube technology made possible. I have not found the specs on the PT to know what it will handle. This becomes a type of Class AB2 operation that can boost the output power while maintaining a reasonable plate dissipation. With the screen at 180 volts the grid voltage swings from a minimum of -6 volts to a maximum of zero volts. This grid acts as a shield between the screen grid and plate so that the secondary electrons cannot be attracted back to the screen grid. 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. the grid resistors also function as "stoppers" to prevent high frequency. In practice, expect around 30% less than this. 5 V Zero-signal plate current 87 mA Max signal plate current 105 mA Zero signal grid no. One of these days, I want to measure the output power and then try the amp with 6L6's and EL34's. In general, Beam Power tubes (such as the 6V6 and 6L6) will exhibit less of a potentially damaging Screen-Grid current rise at maximum signal excursions than Power Pentodes (such as the EL34 and 6BQ5/EL84). The transfer curves for the screen current show about 3mA for an imagined 300V screen curve (red) and a -20V grid. The Russian 6P1P beam tetrode was chosen for the power stage - it has ratings similar to the 6V6 and can be found at low prices. In this case, plate voltage increases by 100V when grid voltage is decreased by 1V while plate current remains constant at 1. filter caps can kill rectifiers with their current draw). Forming the electrons into beams increased the space charge near the plate, which then repelled secondary electrons back to the plate, eliminating the need for a surpressor grid. A key feature of beam tetrodes is that the control and screen grids are wound concentrically so that the screen grid is in the "shadow" of the control grid. Here the IC1 is wired as a. The "screen grid" as it is often called makes the valve more efficient than a triode, especially in power amp duties. edu 28, 28a, 28Mil, 28aMil. By David C. Paul, Positive screen current means that current flows into the grid, and negative screen current means that current flows out of the grid. Blue fire inside 6v6 in a fender 5f2 diy replica (details in the comment) Close. 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. The 2k ohm current limiting resistor drops 40V from the B+ node. Applying DC screen-voltage does NOT increase gain because grid-to-screen amplification can not take place unless input signal voltage is applied between the grid and the screen. Could get less chirp in XTAL control, if a voltage divider design is used in screen grid of 6AG7 to stabilize. This was caused by secondary emission from the plate back to the screen-grid. QMB-25 THE QUADRA SINGLE-ENDED MONO BLOCS. >Is the Shuguang EL34 robust enough to withstand high B+ applications? >The specs for the EL34 list 800VDC. Usually 470ohm 1watt but I guess using 2watts don't hurt it. In practice, expect around 30% less than this. " General Considerations One sometimes sees crystal oscillator circuits with no r. The screen grid (G2) can be fed from the main supply or a half voltage DC (up to 325V DC), allowing you to select the operating mode that most closely represents the amplifier operating conditions. Roger Engle is reporting wrong voltage values for B+ as well as for the screen grid line…I’ve checked it against all the diagrams found at bama. The valve was now called a Tetrode. Title: 6V6 6V6G 6V6GT Author: Tung-Sol Subject: JA-FP-2005-11-06 Created Date: 11/6/2005 11:41:14 AM. A Homebrew Transmitter from the 1960’s, Updated for Today’s AM A 6DQ5 Sweep Tube modulated by Four 1625s December 22, 2006, Bob Hansen, NA7RH Here is my opportunity to tell about adventures with the homebrew 6DQ5 transmitter and companion 1625 × 4 plate modulator, and to discuss some of the changes made to these classic. The two valve pin selector controls have been expanded to provide 5 independent selectors for GRID, PLATE, SCREEN, CATHODE, and SUPPRESSOR electrodes, and each have 9 positions. For the triode data, Supply Voltage is just that, NOT plate voltage. 6V6 amplifier schematic. The variable grid voltage supplied by a potentiometer and the C supply should also be. Power from the amplifier plate is coupled to a Pi-network consisting of L1 and the TUNE and LOAD. With respect to cathode Vg Voltage applied to control grid. Tellegen in 1926. A 2k resistor was added before the screen resistors to drop the screen voltage below the plate voltage. CV Specification "Equivalents" of Electronic Valves. The main grid is the one that has the most effect on current. Part #TS-8-600: $2. The demand for greater output power led to paralleled triodes and triodes in push-pull configurations with balanced output transformers. There are a series string of (3) 1N5380 120V 5W Zener diodes bypassed by a 22uF cap from g2 to ground. The 6L6, 6V6, 6550, EL34, 5881, KT66, KT88, KT90, KT100, etc. Control Grid Voltage D. An inexpensive, easy to build diy valve/tube tester For quite some time I have been looking at developing a design for a diy valve/tube tester that is easy to build and uses readily available, low cost parts. Quick change from 7591 to 6L6-GC or Russian 5881 (Scott and Fisher amplifiers) On these amps the cathodes of the 7591A's are usually tied together. Money Back Guarantee Refund in. 6AQ5W/6005 UL Single-Ended 4Ch Power Amplifier with Hashimoto Transformers. This tester is more versatile than the I-177 valve tester. When the screen grid voltage is higher than the plate, electrons emitted from the plate by secondary emission, as it is struck by the energetic primary electrons, are attracted back to the screen grid instead of returning to the plate as occurs in a triode. Running a 6550 in triode mode simply means that the suppressor grid is biased to the anode, normally via a resistor. Want to use it to add multiple forms from different data sources on the same scrollable screen, but fluid grid doesn't seem to allow you to add a form to a data card. If you measure this AC voltage (between control grid and cathode) while testing a tube for Emission, the measured AC voltage will be lower than 60VAC. If it still blows, the tubes are not your problem. Then I substituted a pair of 6L6GCs which have a maximum screen grid voltage of 400 volts. Vacuum tetrode. By David C. 5 volts by choosing a cathode resistor that will give us a voltage drop of 12. the voltages and bias is a little bit of guess work with the help of average plate transfer curves and loadlines from plots with higher screen voltage and higher plate current. If you use the Visseaux 6V6, this voltage will be present on the metal base of the tube. These tubes required about 130 volts of control grid bias when screen voltage was applied. As Berning has made clear, high plate voltage, on the order of 1000V is a desirable for screen-drive designs since a high plate voltage facilitates increased power output and efficiency. 6V6 6L6 7591 KT66 were and are lower power octal based power valves that pre-date the 6CA7, KT88 and 6550. Voltages were not regulated; plate voltage was 600 V, screen was about 250 V. Paul, Positive screen current means that current flows into the grid, and negative screen current means that current flows out of the grid. Buyer Protection. 8mm 108mm 93mm 34mm ELECTRON DEVICES Svetlana SV6L6GC Made In Russia. cathode and grid. Power Socket Fuse 2A 120V Lamp 4 5 1 7 EZ81 3 12AX7 Heater 4 5 9 12AX7 Heater 12AX7 Heater 4 5 5 4 EL84 Heater 5 EL84 18W TMB Schematic www. dockeryamps. The bias for 250-volt, push-pull operation is -15 volts. The unique power supply design makes for chirp free operation on 80 and 40. The -16V grid curve currently crosses the load line at Ia = 125mA. 6V6 Tube Review. By decoupling this voltage with a 180K isolating resistor, it was easy to get -30V for the 200K brightness pot. com that has screen taps. That graph allows a designer to quickly see the peak plate current (occurring when the grid momentarily reaches 0v) at various screen voltages. For 1" to 1 1/8" hole. If you use the Visseaux 6V6, this voltage will be present on the metal base of the tube. Adjusting the bias is a procedure to set the correctly specified negative voltage on the power tube control grid. Yellow Jacket converters not only re-arrange the pin locations of the tubes but also provide the necessary current limiting on the screens and cathode. Generations of hams built single-tube oscillators with grid resistors of that value, and -- as it turns out -- needlessly put up with chirp and yoop that they didn't have to put up with, commonly adding VR-tube voltage regulation at the tube screen grid because the apparent cause of the chirp/yoop was/is screen-voltage regulation. Speakeasy is over and out, but some of their schematics are still being hosted on their archive. Otherwise the circuit and operation are similar to a triode-follower circuit. Also the screen grid is held at the voltage specified. G (rk) Gain of a single stage amplifier with cathode resistor. Power-grid monitoring Featured products 18 Maxim Smart Grid Solutions Benefits • High integration saves board space - Six-channel voltage monitor is available in a tiny 3mm x 3mm µMAX package • Highly adjustable to accommodate changing design requirements - Fixed and adjustable voltage thresholds; adjustable threshold monitors down to. Band coverage includes 160, 80, 40, 30, 20, 17 and 15 meters as shipped from the factory. ("470")ohm stock on the cathode brought the 6v6's plate down about 1. If the screen curvature is sufficient to cancel the grid curvature at comparatively low levels of feedback (5% in the case of the 6V6) why does it not predominate and cause more than the observed distortion as the screen feedback approaches 100% (triode)?. Capacitor voltages vary. The screen-grid voltage is set by the 6CG7 cathode follower; about 25V is what is required for correct 6CM5 anode current. The term most commonly applies to a three-grid amplifying vacuum tube (thermionic valve), which was invented by Gilles Holst and Bernhard D. Fixed bias power tubes have their cathode connected directly to ground and a negative DC voltage applied to their control grid. Atarashi designed this amplifier for the multi-channel SACD application with just four-channels instead of the normal five. The 12ax7 is a miniature high-mu twin triode, each section of which has an individual cathode connection. With the actual plate voltage in the 6x2 receiver, which turned out to be a little less than 250V. There are however plate voltage limitations on the basic 6V6/6V6GT, the basic 6AQ5, and the 6005 of 250v. The screen grid (G2) can be fed from the main supply or a half voltage DC (up to 325V DC), allowing you to select the operating mode that most closely represents the amplifier operating conditions. estimates the Harmonic Distortion (HD) in the operating range corresponding to the selected output headroom. Unfortunately many people tend to ignore screen grid ratings or allowed areas of operation for screen grids as can be found in tube spec sheets. (Actual Plate Voltage) Example: Octal - pins 3 and 8 9 pin - pins 7 and 3. The work of suppressor is to absorb the excess energy of the electrons from the cathode accelerated by the screen grid to guarantee a higher amplification. All in all, a dollar well spent. For 6l6 / 6V6, 220 Ohm resistors work nicely, though 470 Ohm is normal. For 1" to 1 1/8" hole. Since the grid is returned to ground through grid load resistor R-12, the grid will be negative with respective to the cathode by the amount of voltage that is developed across R-13. The 6V6 does about 6 watts output. The 3rd grid (suppressor) should again have little or no. Electronic Valves, (Electron Tubes) Holders and Accessories. US2853611A US626550A US62655056A US2853611A US 2853611 A US2853611 A US 2853611A US 626550 A US626550 A US 626550A US 62655056 A US62655056 A US 62655056A US 2853611 A US2853611 A US 2853611A Authority US United States Prior art keywords potential grid screen cathode space Prior art date 1956-12-05 Legal status (The legal status is an assumption and is not a legal conclusion. Want to use it to add multiple forms from different data sources on the same scrollable screen, but fluid grid doesn't seem to allow you to add a form to a data card. So, @fezz parka, I added the 470 ohm screen grid limiter and got virtually no change to screen grid vs plate voltages. 5mA on the 2K/2W screen resistor. If you measure this AC voltage (between control grid and cathode) while testing a tube for Emission, the measured AC voltage will be lower than 60VAC. >If you also remove the jumper between the PA DISABLE. However, the primary line of defense against grid-bias failure is simple and automatic: The grid-bias supply powers the main control relay, K!. filter caps can kill rectifiers with their current draw). That loads the guitar itself. I swapped the tubes out of the Vibro with a set that I know are good and no difference in performance. This is a simple shunt voltage regulator for the screen grids of SE DC 6V6/6AQ5 finals. Updated March 18, 2020 I've been experimenting for years working to find the right mix of good sounding and reliable 6V6 tubes to stock here at the shop. (Converts 6L6, EL34, 6550, 7027, or 6V6 to EL84) The YJS is for amplifiers with fixed bias power tubes. With the broken rectifier valve removed the mains was connected via the safety lamp and variac, the voltage slowly increased. the screen grid serves as the "plate. Higher mu tubes can run with higher plate or screen voltage because of the reduced effect of the plate or screen on the grid. In general, Beam Power tubes (such as the 6V6 and 6L6) will exhibit less of a potentially damaging Screen-Grid current rise at maximum signal excursions than Power Pentodes (such as the EL34 and 6BQ5/EL84). A certain amount of flexibility can be had by adjusting the screen grid potential to accommodate a given primary impedance. From our review of the Tung-Sol 6V6GT: "The Tung-Sol 6V6-GT is an outstanding tube and I feel it delivers a much smoother overdrive that you could describe as creamy instead of crunchy. The screen grid (G2) can be fed from the main supply or a half voltage DC (up to 325V DC), allowing you to select the operating mode that most closely represents the amplifier operating conditions. Moving the load to the 4-ohm taps has its pluses. The Tungsol 6V6 has a geometry designed to safely handle the higher voltages used in guitar amps-plus heavier plate and grid materials. 6W This is slightly above the maximum 12W rating of a 6V6, which is rare for Class AB. Z 1x12 conv ibanez: 570 custom flame top petrucci jpm p4 3120 ant prestige 7620 gn 505 bm 5 strng bass fender american sienna burst gibson les paul custom brandy. The JJ 6CA7s I have are beam tetrodes, but as I said earlier, the old GE and Philips tubes I have are power pentodes. Screen voltage. Glowing screen grids, regardless of being found within beam power tubes or pentode tubes, in most cases are just a sure sign of running a tube outside of its specs. The datasheets for a "real" 6V6 show a typical plate current of 34mA at a plate voltage of 315V, screen voltage of 225V, and a grid voltage of -13V. For 1" to 1 1/8" hole. In either case, the suppressor grid is much more negative than the plate. Vg2=Screen or grid #2 voltage. Shows how to use VFO with this rig. Power from the amplifier plate is coupled to a Pi-network consisting of L1 and the TUNE and LOAD. These are unused on 6V6's (and 6L6's). The first of this family of tubes to be introduced was the 6V6G by Ken-Rad Tube & Lamp Corporation in late 1936,. As the plate voltage is made more negative, the electrons get slowed down more and more in passing from screen grid to plate, and as a result, the space. Note Carefully: The transformer shown in Figure 1 must be used, and a Variac is then used to vary the primary voltage. The Screen Grid is an extra element added to the basic three element configuration of triode tubes to form a four element configuration tube called a tetrode. However, last year I had both a GZ34 and 6v6 that were both JJ go south. cathode and grid. A pentode is an electronic device having five active electrodes. Grid Voltage 2 (U g2) ≤ 450 V, 250 V typical Replaced the screen grid resistors with new ones that were also matched in. Screen Grid Control. All power supplies are potential killers if you touch high AC voltage. The difference being on the el34's pin 4 is the unused pin (on my last build) and on the 6v6's pin 6 is unused. Maggie power tube circuit (I think), I am running a single 6V6 that seems very hot: 342v at the plate, 40ma of current through the cathode, and 13. I have not found the specs on the PT to know what it will handle. If a substantially different voltage appears on the screen grids of both tubes, an imbalance in bias current could occur. Many schematics online says to just hook the screen to the plate, others suggest a ohm resistor to help with oscillations. The transfer curves for the screen current show about 3mA for an imagined 300V screen curve (red) and a -20V grid. Powerscreen Powergrid 800. Screen voltage. Will they survive in the >550-600VDC range? Anyone trusting 'today's' EL 34 of 800 full tilt is a fool. 6L6 plates and heater are fine but I have no screen or cathode voltage and resistor 69A (1650 ohms from screens to center tap of output transformer) is getting way too hot!. ) The suppressor grid is internally tied to the cathode, except in the case of the E80L where it must be connected externally (pins 9 & 3). The suppressor grid is positioned between the screen grid and the plate. I would start by swapping the 12AX7 tubes around and seeing if there is any change. The grid current is quite high, resulting in about -60V across the 47K resistor. With respect to cathode Vg Voltage applied to control grid. So for now, the amp still has four 6L6's, but two valves have 1K 5W while the other two valves have 470R 5W - split up between each side of the push pull/OT of course. Negative high-voltage keying is done at "X", and screen-grid keying at "Y. My first rig, way back in 1967, was based on this rig. 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. The beam tetrode consists of a basic tetrode valve or vacuum tube in which beam forming plates are added between the screen grid and the anode. drive the screen grid, with the control grid bypassed to AC ground, and used only to set a Q-Point current. It does provide more gain (which I didn’t need) and the high frequencies were a bit faster and seemingly more extended, but there were two disadvantages that made me return to triode each time. I have not found the specs on the PT to know what it will handle. The DC is used as the screen grid supply for the 6AQ5 pass tubes and the low voltage for their heaters. line and so only a proportion of the H. If you have a tetrode or pentode tube for a regenerative detector, then maybe screen grid control is the way for you to go. The newer 6V6GTA/B/C limit is higher at 300v, the 6V6S has a huge 450v limit, and the 7-pin 6669. Re: Ameco AC-1 ECO: Plate modulated « Reply #10 on: February 26, 2014, 02:22:01 PM » I just put my new Ameco AC clone on the air on 40 meters (actually into a 50 ohm dummy load). A five element tube is called a "pentode". Speakeasy is over and out, but some of their schematics are still being hosted on their archive. The JJ 6V6 can even be used in place of a 6L6 in some amplifiers. As said, EL506 is an excellent pentode and not much can be seriously improved here. Want to use it to add multiple forms from different data sources on the same scrollable screen, but fluid grid doesn't seem to allow you to add a form to a data card. CV Specifications against Commercial, Older designations and Prototypes HERE. Tetrode tubes have four electrodes—the aforementioned cathode and plate, as well as a control grid and screen grid. If the #1 grid has enough negative voltage applied, grid 2 and anode fields can not over come that negative. This is how the old Fender amps were and they used no screen resistors at the tube sockets. Money Back Guarantee Refund in. My other option that I referred to was to put in two EL34's only, on the sockets that have the 1K 5W screen grid resistors. The common value for the input grid resistors for an EL 34 amp is indeed 5k6 whereas the common values for 6L6 amps are between 1k5 and 3k3. Mullard made a wonderful version of this tube, and is what is usually found in the USA in a European made 7189. I have the regulator circuit wired up and ready for preliminary testing. Another option is to use a small value dropping resistor right before the screen filter cap to keep screen voltage lower than plate voltage. My other option that I referred to was to put in two EL34's only, on the sockets that have the 1K 5W screen grid resistors. Electronic Valves, (Electron Tubes) Holders and Accessories. The Gm ( transconductance ) is the difference between the lk1 and lk2 currents, expressed in mA / V, or in uS, or in umhos, by multiplying the value by 1000 : 1mA/V = 1000 uS = 1000 umhos. It would not be too far-fetched to get 49mA per tube when running at a plate voltage of 387V, especially when considering the screen voltage is also 387V (no screen grid resistors in the Jet, but. ) connection 6. RCA RC-18 manual from 1956, and Brimar 7 from circa 1957 both show same circuit configuration. The primary cause of chirp in these simple rigs is the screen voltage supply. Im mostly worried about the shared CCS on the cathodes and if anything can go wrong with the screens which will have separate regulated voltage. The 6CW5/EL86. The grid resistor to this output tube is split into two sections, R2 and R3, forming a voltage divider (3:1 with the values shown in the schematic). The only cou-pling between the oscillator and the load is through the stream of the 6AG7. Then last night I installed two new 1K 5W screen resistors on the other two sockets so I can try running two EL34's in half power mode. They will melt quickly if fed 300 volts or more!. The control circuit provides dedicated metering of grid, screen and plate current. negative voltage to pin 1 of V 2. Screen voltage. The work of suppressor is to absorb the excess energy of the electrons from the cathode accelerated by the screen grid to guarantee a higher amplification. The Tungsol 6V6 tube has a geometry designed to safely handle the higher voltages used in guitar amps ­ plus heavier plate and grid materials. mu=amplification factor. 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. 18watt Technical Discussion. The base voltage of the grid, the voltage that is present whether there is a signal or not, is referred to as the bias voltage. As the plate voltage is made more negative, the electrons get slowed down more and more in passing from screen grid to plate, and as a result, the space. A 2k resistor was added before the screen resistors to drop the screen voltage below the plate voltage. These are plate and screen power dissipations verses power output and plate and screen currents verses power output. At some instant in time, shown as t on the time scales, the grid voltage has a value denoted e g on the grid voltage. The 10k grid stopper is a good idea and I wonder if a screen grid stopper would not be a good thing too. The unique power supply design makes for chirp free operation on 80 and 40. The transfer curves for the screen current show about 3mA for an imagined 300V screen curve (red) and a -20V grid. I s: Screen grid current (tetrodes and pentodes). This becomes a type of Class AB2 operation that can boost the output power while maintaining a reasonable plate dissipation. The input pentode would have its screen follow the grid, while the output pentode's screen would see 100% of the power-supply noise. Only three pins Bias voltage for the FET is derived gate of the FET when you first switch are needed on the valve base, to replace the valve's anode, from a potential divider, fed from the on your receiver. The product design allows the machine to operate in very confined spaces and the. The control grid controls how much plate current actually flows within the maximum amount set by the screen grid voltage. The Zener diode string fixes the screen voltage, with a current-limiting resistor in the string that biases the current at a fixed amount, e. The work of suppressor is to absorb the excess energy of the electrons from the cathode accelerated by the screen grid to guarantee a higher amplification. 2 DC (screen) voltage 500 V Grid no. I would have liked to heard this one on my B&W speakers, but I sold it before I had a chance. Capacitor voltages vary. It did take me a while to wrap my head around sliding screen operation, but it turns out 1k screen grid stoppers should be fine. The additional renewable power means PRPA now generates about 50% of its electricity from noncarbon sources. I am assuming Va is the same as plate voltage also. By adjusting the screen voltage, this will control the gain and the feedback. Strictly speaking the peak screen voltage was about twice that but data on other tubes and for a single ended triode connected 6L6 seemed to use the max screen voltage as the operating voltage for a triode connection. Due to the “electron-coupling,” any changes in the load have very lit-tle effect on the frequency-controlling. Pentodes connected as Triodes 16 Screen grid voltage is not fixed anymore, but swings with anode Screen/shielding function of g2 is disabled Screen grid area effectively added to anode area Possible screen grid connections Screen grid connected to anode Preferred method to connect g2!. grid voltage grid voltage peak af grid to grid voltage zero—signal plate current zero—signal grid current maximum signal plate current maximum signal grid '2 current load resistance power output total harmon 'c distortion ampl if i er tubes 6. However, the. Cathode voltage is 26V, so current is (26/470) = 55mA. The input pentode would have its screen follow the grid, while the output pentode's screen would see 100% of the power-supply noise. ULTRA-LINEAR DISTRIBUTED LOAD HIGH-FIDELITY VACUUM TUBE AUDIO AMPLIFIERS * * * ULTRA-LINEAR OPERATION, also known as DISTRIBUTED LOAD OPERATION, is a term when applied to single-ended or push-pull vacuum tube audio amplifiers, that describes the particular output stage configuration whereby the Screen Grids (Grid 2) of Tetrodes, Pentodes or Beam Power Tubes are fed from a. Also the screen grid is held at the voltage specified. Glowing screen grids, regardless of being found within beam power tubes or pentode tubes, in most cases are just a sure sign of running a tube outside of its specs. On a 6V6 tube, the pin is 4. Especially if the tubes were well balanced. This method should be avoided. As the screen grid voltage is raised or lowered, the characteristic curves expand or contract in the vertical direction. The following graph shows open key voltage with screen voltage regulated at 200 volts, anode voltage of 400 volts, while grid bias is varied from -0 to -80 volts: fig 4. The power supply filter capacitors all need to be rated at at least 400vdc. This tester uses regulated power sources for the bias, plate, & screen voltages, as well as modified operating & testing procedures. The screen grid is part of a tetrode or pentode (in our case) tube. 8mm 108mm 93mm 34mm ELECTRON DEVICES Svetlana SV6L6GC Made In Russia. Unfortunately, this does not include the schematic to the "Absolute Modeling Amp. Vacuum Tube - 6V6, JJ Electronics. First, here is the pin connections for a 6SN7. Type 6V6-GT may be supplied with pin No. Find the wire connecting between the two cathodes and remove it. 4 volts and zero. p = Pentode Unit. It's not redundant. Control Grid Voltage D. (Pin 4 relative to Pin 3 with no signal) The schematic has a 1K resistor on the power rail that feeds the screen grid. The newer 6V6GTA/B/C limit is higher at 300v, the 6V6S has a huge 450v limit, and the 7-pin 6669. All in all, a dollar well spent. On either tube, it looks like the screen resistor goes across the unused pin and the grid resistors. It is known that a limiting factor in operating screen grid tubes in the normal operation, i. The anode resistance is measured at 240V and 260V, it is the slope of this line, 250V is the center value, if you look at a 6V6 triode curves you will see the line is. I have a 6V6 PP PA amp from late 1940's with same supply for OT CT and screens, and no grid or screen stoppers. Screen Grid Voltage: % of Rail Voltage: % of Rail Voltage: Test Points: - Between D1-R10 - T4 or Btwn R10-R12 - Between R12-R13 - Pin 3 - Pin 1 - Pin 6 - Pin 8 All readings referenced to ground. I have the regulator circuit wired up and ready for preliminary testing. This function is an application of local NFB. The 6V6GT is a beam pentode and therefore flows little screen current so the 5E3 can get away with running without screen grid resistors. Title: 6V6 6V6G 6V6GT Author: Tung-Sol Subject: JA-FP-2005-11-06 Created Date: 11/6/2005 11:41:14 AM. Vrms I/P is the rms voltage required to drive the valve to full output. This seems like a recipe for short tube life. read the whole thing here. Only three pins Bias voltage for the FET is derived gate of the FET when you first switch are needed on the valve base, to replace the valve's anode, from a potential divider, fed from the on your receiver. Plate voltage DC voltage measured between plate and cathode. The plate and screen grid operate at different voltages, so only pentode mode can be used. 6 mA Maximum-signal screen current 22 mA Load Resistance, plate-to-plate 5600 ohms Total harmonic distortion 1. So, @fezz parka, I added the 470 ohm screen grid limiter and got virtually no change to screen grid vs plate voltages. grid voltage plate current grid current load resistance power output distortion class a (a p p roy. The drive circuitry of the control grids is not shown - I assume perfect. Electronic Valves, (Electron Tubes) Holders and Accessories. If this happens, the op-amp will immediately switch Q2 into its "on" state of about an ohm and shunt the current surge harmlessly to ground. for 6V6 this would be pins 4 & 3. read the whole thing here. Since the grid is returned to ground through grid load resistor R-12, the grid will be negative with respective to the cathode by the amount of voltage that is developed across R-13. Find the wire connecting between the two cathodes and remove it. ) connection 6. I used the standard 40% screen grid tap, but the 6V6 is supposed to be designed for 23% screen grid taps in ultralinear mode. With the second triode conducting, a high positive d-c voltage appears across R16, the grid resistor for the first-triode section of the sweep oscillator V 3. Current production 6V6 tube information. The power tube grid voltage is always negative on fixed bias amps and a hotter bias will have the grid voltage closer to zero. The cutoff Bias is greatly influenced by the screen and Anode voltage values. This is how the old Fender amps were and they used no screen resistors at the tube sockets. If a substantially different voltage appears on the screen grids of both tubes, an imbalance in bias current could occur. There is a reason why quality equipment often uses a regulated screen supply and lower screen voltage. 5mA on the 2K/2W screen resistor. The 6P1P (Russian: 6П1П) is a Soviet-made miniature 9-pin beam tetrode vacuum tube with ratings similar to the 6AQ5, EL90 and the 6V6. Download MU Origin 1. G (rk) Gain of a single stage amplifier with cathode resistor. Plate current overdrive trip is provided at 1. The screen grid establishes a plane of near zero AC potential in the space, yet electrons can pass through the screen openings to the anode. As a remedy, the grid was then tuned in the 40 mt band while leaving the plate pi network on the 20 mt (frequency doubler). Roger Engle is reporting wrong voltage values for B+ as well as for the screen grid line…I’ve checked it against all the diagrams found at bama. On a 6V6 tube, the pin is 4. " General Considerations One sometimes sees crystal oscillator circuits with no r. It does occur to one that the RCA K-80 used a pair of 6F6 output tubes, which are pentodes having higher operating voltages and screen grid currents than a pair of 6V6 beam power tubes. The newer 6V6GTA/B/C limit is higher at 300v, the 6V6S has a huge 450v limit, and the 7-pin 6669. I've mounted the output tube grid and screen resistors on pins 1 and 6 of the octal sockets. Voltages were not regulated; plate voltage was 600 V, screen was about 250 V. Notes on this valve data; Vp is the voltage between plate and cathode, not necessarily the same as the supply voltage. Includes 12V to 150V voltage multiplier: X: 26. Screen voltage is derived from the HV bus via a 6800Ω dropping resistor. H/F means "Heater or Filament" voltage and current specifications. If your computer is slow, we recommend to download a smaller or perfectly optimized map. Pentodes connected as Triodes 16 Screen grid voltage is not fixed anymore, but swings with anode Screen/shielding function of g2 is disabled Screen grid area effectively added to anode area Possible screen grid connections Screen grid connected to anode Preferred method to connect g2!. KT88 single ended amplifier is just like good triode amplifier sound and good bass. The 2k ohm current limiting resistor drops 40V from the B+ node. Voltage readings to ground were 307vdc plate, 315vdc screen, and 18. In grounded grid without screen voltage, the driving impedance per tube was just over 100 ohms. After Final Adjustments After Initial Modifications Off On 12AX7 -- V1a FtSw1: 12AX7 -- V1b FtSw2: 6V6 12AX7 -- V1a FtSw1 12AX7 -- V1b FtSw2. They will melt quickly if fed 300 volts or more!. The tone is similar to the 5F1 but has less punch and volume due to the flawed power section. 6AQ5W/6005 UL Single-Ended 4Ch Power Amplifier with Hashimoto Transformers. The term most commonly applies to a three-grid amplifying vacuum tube (thermionic valve), which was invented by Gilles Holst and Bernhard D. edu 28, 28a, 28Mil, 28aMil. This means I end up using a lot of their stuff. Negative high-voltage keying is done at "X", and screen-grid keying at "Y. I have a 6V6 PP PA amp from late 1940's with same supply for OT CT and screens, and no grid or screen stoppers. Always refer to your original equipment manufacturers specifications to confirm biasing requirements for your specific amplifier. Typical operating conditions are given in the 6AQ5 data sheet, and these were used in the 6x2 receiver. The 6V6 is dissipating about (352-26)*(26/470 -. The plate and screen grid operate at different voltages, so only pentode mode can be used. To run a beam power or pentode tube in triode mode, strap the screen grid to the plate (e. Most of the wax paper capacitors tested leaky, including the grid capacitor for the 6V6 output valve. The 7027 is also an octal base tube, but it uses the "8HY" base. I am working on a built Sta-level to see if there is a way to make the 6V6 stage clip later. As a remedy, the grid was then tuned in the 40 mt band while leaving the plate pi network on the 20 mt (frequency doubler). On a 6V6 tube, the pin is 4. This is a simple shunt voltage regulator for the screen grids of SE DC 6V6/6AQ5 finals. The base voltage of the grid, the voltage that is present whether there is a signal or not, is referred to as the bias voltage. Like pentodes, beam-power tetrodes can generally be triode-strapped to create a frankentriode. 5mA on the 2K/2W screen resistor. Due to the “electron-coupling,” any changes in the load have very lit-tle effect on the frequency-controlling. Since both triode sections of V 3 have a common cathode. MOSFET substitute for the 6V6 valve. Not very much is known about these amps, aside from some scattered user reviews from the time they were made. Vg1=Negative grid voltage. >Is the Shuguang EL34 robust enough to withstand high B+ applications? >The specs for the EL34 list 800VDC. I have not found the specs on the PT to know what it will handle. If these are available points A and C should be connected to them and the power stage will then be 'ultra-linear'. If you can measure the voltage on pin 3 and pin 4 of your amp at idle, speaker connected but nothing in the input and volume control all the way off I can. My first rig, way back in 1967, was based on this rig. Anode power dissipation at operating point. The typical gm-value for 6V6GTA or 6V6EH is. This is the "industrial" version of the 6BQ5. The grid bias is the DIFFERENCE in voltage between the cathode and the grid not the voltage between the grid and ground. 5, the variations have been indicated next to the plate volt-age and grid voltage scales of a typical constant-current curve. Grid 3 to cathode. The 34 took out my fuse and was replaced. Note Carefully: The transformer shown in Figure 1 must be used, and a Variac is then used to vary the primary voltage. Note how these variations center about the dc plate voltage and the dc con-trol grid bias. negative voltage to pin 1 of V 2. As said, EL506 is an excellent pentode and not much can be seriously improved here. I tried the D3a in pentode several times. 6V6 6L6 7591 KT66 were and are lower power octal based power valves that pre-date the 6CA7, KT88 and 6550. 3V) that heats the cathode to free up electrons in preparation for current flow. The upper jacks are 6V6 #2 cathode, cathode ground, and 6V6 #1 cathode. Suppressor grid: In the pentode valve / vacuum tube, the suppressor grid is generally maintained at a low voltage, often connected directly to the cathode. Z 1x12 conv ibanez: 570 custom flame top petrucci jpm p4 3120 ant prestige 7620 gn 505 bm 5 strng bass fender american sienna burst gibson les paul custom brandy. The control circuit provides dedicated metering of grid, screen and plate current. The JJ 6CA7s I have are beam tetrodes, but as I said earlier, the old GE and Philips tubes I have are power pentodes. DC plate voltage 800 V Grid no. Beam power tetrodes have a anode, cathode, grid, screen grid, and an electron beam-forming plate instead of the pentode’s suppressor grid. 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. 1 (control) voltage 16. 6V7-G - Dual diode, Medium-mu Triode. One of these was the G1/1070-A model, with just a pair rated at 70. As the screen grid voltage is raised or lowered, the characteristic curves expand or contract in the vertical direction. line and so only a proportion of the H. Two front panel LEDs indicate overdrive conditions for the control grid and screen grid circuits. My other option that I referred to was to put in two EL34's only, on the sockets that have the 1K 5W screen grid resistors. The plate and screen grid operate at different voltages, so only pentode mode can be used. Excellent and thanks all! I will be working on the 32S-3 this coming week and you have all provided some incredibly good information! Jeff AK6OK On 3/21/15, 7:25 AM, "Alan Chandler" wrote: >Just removing the 5R4 from the power supply does not remove the screen >voltage from the 6146s and can damage the tubes. Another option is to use a small value dropping resistor right before the screen filter cap to keep screen voltage lower than plate voltage. drive the screen grid, with the control grid bypassed to AC ground, and used only to set a Q-Point current. It is biased at a very low voltage: either ground potential, or it is internally tied to the cathode (i. Common problems faced with 15-watt tube amps. (Actual Plate Voltage) Example: Octal - pins 3 and 8 9 pin - pins 7 and 3. Updated: Wed, June 10, 2020 4:05 PM Granite Development. Numbers shown in light yellow background are used in series-string configurations. Suppressor Voltage D. The screen grid in a power tube carries some current, which causes it to heat up. If you have an amp which uses power tubes which are not listed above, you will need to consult a spec manual (the RCA RC-30 Receiving Tube Manual is one of the best) for the basing, and adjust. 5, the variations have been indicated next to the plate volt-age and grid voltage scales of a typical constant-current curve. By adjusting the screen voltage, this will control the gain and the feedback. If you want to use my layout with EL34's, these pins connect inside the tube, so you'll have to mount these resistors somewhere else. There are a series string of (3) 1N5380 120V 5W Zener diodes bypassed by a 22uF cap from g2 to ground. Includes parasitic resistors on control grid and screen grid. v-l v-2 v-3 v-5 6SC7 6AN8 6Y6 6V6 5Y3 O 270 120 100 6. The screen performs the task which the anode in a real triode performs. Yea, like good ole 5U4, 5R4, 5AR4 etc and variants …. The power supply filter capacitors all need to be rated at at least 400vdc. Glowing screen grids, regardless of being found within beam power tubes or pentode tubes, in most cases are just a sure sign of running a tube outside of its specs. The negative bias voltage is often designed to be adjustable by way of a bias pot. Screen Voltage D. That graph allows a designer to quickly see the peak plate current (occurring when the grid momentarily reaches 0v) at various screen voltages. As a result, a tetrode can only be used if the circuit design is such that this part of. Band coverage includes 160, 80, 40, 30, 20, 17 and 15 meters as shipped from the factory. Pin-8, Cathode-beam plates: Typical class-A amplifier operation; Anode voltage: 250 V: Anode current: 140 mA: Screen voltage: 250 V: Bias voltage-15 V: Anode resistance: 12 kilohms: Typical class-AB amplifier operation (Values are for two tubes) Power output: 100 W. choke in series with the grid leak across the crystal, but the slight saving in expense hardly justifies the improvement in performance that can be obtained by using the choke. Plate current overdrive trip is provided at 1. (Actual Plate Voltage) Example: Octal - pins 3 and 8 9 pin - pins 7 and 3. The Tungsol 6V6 tube has a geometry designed to safely handle the higher voltages used in guitar amps ­ plus heavier plate and grid materials. I bought the JJ 6v6 S to use in this amp, which is a beefed up 6v6 and per the JJ spec sheet, if I am reading it right, can handle plate and screen voltages of 450V, so I'm not too worried about tube life. 0 Store: AK985 Audio Store. As the screen grid voltage is raised or lowered, the characteristic curves expand or contract in the vertical direction. They all report for B+ = 280V, screen grid line = 100V while Roger’s reprint states for B+ = 250V and. Review Telefunken null. Will they survive in the >550-600VDC range? Anyone trusting 'today's' EL 34 of 800 full tilt is a fool. G (rk=0) Gain of a single stage amplifier without or bypassed. 1 DC (control) voltage -16. The "screen grid" as it is often called makes the valve more efficient than a triode, especially in power amp duties. 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. The output stage is straightforward textbook design. Updated: Wed, June 10, 2020 4:05 PM Granite Development. 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. The suppressor grid is positioned between the screen grid and the plate. i've determined that the filter cap(s) in my clone Champ (6V6, #AA764) were being destroyed, and it was suggested to me that it might be the 6V6 screen grid killing them. You'll notice that the input signal goes to pin 6 (which is unused on the 6V6) and then hops a 1. If a substantially different voltage appears on the screen grids of both tubes, an imbalance in bias current could occur. Only three pins Bias voltage for the FET is derived gate of the FET when you first switch are needed on the valve base, to replace the valve's anode, from a potential divider, fed from the on your receiver. grid voltage plate current grid current load resistance power output distortion class a (a p p roy. I would start by swapping the 12AX7 tubes around and seeing if there is any change. Probably the best non-USA 7189 available. for 6V6 this would be pins 4 & 3. They all report for B+ = 280V, screen grid line = 100V while Roger’s reprint states for B+ = 250V and. It is known that a limiting factor in operating screen grid tubes in the normal operation, i. The rectifier and preamp tubes were OK but the 6V6 failed grid emissions testing and was replaced with a good tube. 5K "grid stopper" resistor before it goes into the power valve. Operate them in full pentode mode with a regulated screen supply. When the screen grid voltage is higher than the plate, electrons emitted from the plate by secondary emission, as it is struck by the energetic primary electrons, are attracted back to the screen grid instead of returning to the plate as occurs in a triode. the screen grid serves as the “plate. The grid current is quite high, resulting in about -60V across the 47K resistor. Maximum acceptable grid voltage for the installed inverters. It controls the number of electrons passing through it to the plate. That graph allows a designer to quickly see the peak plate current (occurring when the grid momentarily reaches 0v) at various screen voltages. Voltage anode triode. Control Voltage Plate Dissipation MAXIMUM RATINGS AND TYPICAL OPERATING CONDITIONS RADIO FREQUENCY POWER AMPLIFIER CLASS "C" UNMODULATED Maximum TYPICAL OPERATION, TUBE* 170 1. RCA 6V6 Very Strong Vacuum Tube ^^^^^ ***** Tested on our proprietary tester , the E3444. 6W This is slightly above the maximum 12W rating of a 6V6, which is rare for Class AB. grid voltage plate current grid current load resistance power output distortion class a (a p p roy. 9 360 225 18 52 78 3. The Screen Grid is also incorporated into multi-electrode tubes such as pentodes, heptodes and octodes. I am now appraising my collection of valves and shall be selling some on a private basis. With the actual plate voltage in the 6x2 receiver, which turned out to be a little less than 250V. Adapter - Yellow Jacket, Converts 6V6 to EL84/6BQ5 - This Yellow Jacket converter is a specialized adapter which permits the use of EL84/6BQ5 power tubes in place of 6V6 type tubes. This divided-down voltage is applied to the grid of the paraphase stage, V1B. This tester uses regulated power sources for the bias, plate, & screen voltages, as well as modified operating & testing procedures. THE SCREEN GRID (GRID # 2) - PRIMARY FUNCTIONS. As a result, a tetrode can only be used if the circuit design is such that this part of. Assuming for the sake of argument that the supply voltage for the whole ECF83 stage is 250, and the screen grid is fed through 1 Megohms, limiting it to 220 µA and assuming this holds it down to 30V, which is good. Meet the best flatscreen TVs designed for the developing world to run on 'off-grid' energy, such as personal solar. In practice, expect around 30% less than this. The 6P1P (Russian: 6П1П) is a Soviet-made miniature 9-pin beam tetrode vacuum tube with ratings similar to the 6AQ5, EL90 and the 6V6. The second mode is with a 1K resistor connected and the B+ is powering the screen grid. The 6V6 is dissipating about (352-26)*(26/470 -. choke in series with the grid leak across the crystal, but the slight saving in expense hardly justifies the improvement in performance that can be obtained by using the choke. Notes on this valve data; Vp is the voltage between plate and cathode, not necessarily the same as the supply voltage. Cathode resistor. _____ Michael Brebes Instrument/amp/ pickup repair MSA D10 Classic/Rickenbacher B6/ Dickerson MOTS/Dobro D32 Hawaiian/ Goldtone Paul Beard Reso. The 6V6 and 6V6-GT are equivalent in performance. Adding a 470 ohm 3 watt resistor to the 5E3 can add sweet sounding power tube distortion so it is a modification to consider. Quick change from 7591 to 6L6-GC or Russian 5881 (Scott and Fisher amplifiers) On these amps the cathodes of the 7591A's are usually tied together. If you want to use my layout with EL34's, these pins connect inside the tube, so you'll have to mount these resistors somewhere else. The JJ 6CA7s I have are beam tetrodes, but as I said earlier, the old GE and Philips tubes I have are power pentodes. Screen grid resistors will also increase the screen voltage drop when screen current flows which will increase the amount of power tube distortion caused by screen voltage drop. In an attempt to improve linearity and reduce drive power requirements, I built a screen and bias supply. The first high-power ZOTL amp released circa 1996, the ZH270, was configured for screen drive, but the Ultralinear amp reviewed here is driven conventionally. R k: Cathode resistor. You can also see this effect, for the 0v gridline only, shown in the top graph of page 6. To run a beam power or pentode tube in triode mode, strap the screen grid to the plate (e. Screen Grid Control. US2853611A US626550A US62655056A US2853611A US 2853611 A US2853611 A US 2853611A US 626550 A US626550 A US 626550A US 62655056 A US62655056 A US 62655056A US 2853611 A US2853611 A US 2853611A Authority US United States Prior art keywords potential grid screen cathode space Prior art date 1956-12-05 Legal status (The legal status is an assumption and is not a legal conclusion. 9-in 160-Watt Solar Panel. The 7027 is also an octal base tube, but it uses the "8HY" base. Plate voltage DC voltage measured between plate and cathode. This provides a constant screen grid supply voltage for the 6AQ5s. Va Voltage applied to anode. This is how the old Fender amps were and they used no screen resistors at the tube sockets. 2 DC (screen) voltage 500 V Grid no. Overall this tube has a warm and balanced tone with incredible separation and response. The EL34 is a pentode, while the 6L6, which delivers a similar range of power output, is a beam tetrode which RCA referred to as a beam power tube. Filament voltage is also controlled. The bias determines how much current the tube draws when there is no input signal. Top mounting (mounted from the outside of the chassis), mounting holes spaced 1 1/2" apart. " General Considerations One sometimes sees crystal oscillator circuits with no r. ) Probably the author is trying to dodge trouble around patents or some other reason. After installing thousands of tubes, here are my two top picks and why. Cathode voltage is 26V, so current is (26/470) = 55mA. I used a 6V6GT and the grid-plate circuit. p = Pentode Unit. ) voltage for 0. It is biased at a very low voltage: either ground potential, or it is internally tied to the cathode (i. The result is a tetrode, or four-element valve, devised by Hull about 1927. Inspired by music of the 6V6 vacuum tube amplifier of Dennis's youth, this design might be the best he has heard in 57 years since listening to his. The screen grid resistors are 1Kohm 5W resistors used to limit current and are pretty essential with modern tubes if you want them to live. Some, but not all, were versions of existing American beam tetrode tubes or European power pentodes, such as the KT66 (6L6), KT77 (EL34 and 6CA7), KT88 (6550), and KT63 (6V6). 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. Control Voltage Plate Dissipation MAXIMUM RATINGS AND TYPICAL OPERATING CONDITIONS RADIO FREQUENCY POWER AMPLIFIER CLASS "C" UNMODULATED Maximum TYPICAL OPERATION, TUBE* 170 1. 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. i've determined that the filter cap(s) in my clone Champ (6V6, #AA764) were being destroyed, and it was suggested to me that it might be the 6V6 screen grid killing them. Operating Bias: Examination of the 6146B tube data sheets shows that for linear operation the tube bias can be set for a zero signal plate current of 12 to 25 mA. Screen Voltage D. Fixed bias power tubes have their cathode connected directly to ground and a negative DC voltage applied to their control grid. Only given for power triodes. Numbers shown in light blue background are cold-cathode tubes. 10 W rms power so need more than 20W capability of power. The grid acts like a sieve. 220k grid leak resistors, also a good idea to put in grid stoppers (4k7 - 10k) Ideal screen voltage is about 270 volts, but you can run higher if you really want to (but what does it cost to put in a resistor ladder and a bypass cap for each screen?). read the whole thing here. feedback will effect this difference. 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. Most of the wax paper capacitors tested leaky, including the grid capacitor for the 6V6 output valve. 6BQ6, like the 6V6, doesn't require the additional help of local NFB. 6V6 Trainwreck Express in recycled combo cabinet: I've mounted the output tube grid and screen resistors on pins 1 and 6 of the octal sockets. If you have an amp which uses power tubes which are not listed above, you will need to consult a spec manual (the RCA RC-30 Receiving Tube Manual is one of the best) for the basing, and adjust. When you turn on your tube amp, the tube filament at the center of the bottle receives a voltage (usually 6. This class of tube (eg 807, 2E26, 6146, 4CX series) has the screen grid physically positioned close to the control grid (Grid 1) and tend to self-oscillate or suffer thermal runaway when the screen grid voltage is higher than their rated screen-grid voltage, which is always the case with conventional ultra-linear service, thus rendering them. I tested with a guitar and decided that the lack of clean headroom might deserve some investigation. Sonically the triode configuration is warmer and has more. Note the screen supplies are often half the anode supply voltage, but you also see amps where the screens are dropped via resistors directly from the main supply if its below about 400 volts. Buyer Protection. The screen voltage is usually held more-or-less constant so that electrons are accelerated towards it, and after they pass between the grid wires it is too late for them to slow down and do anything else, so they crash into the anode. To keep the output power low, being able to overdrive the power tubes in push-pull at the same time, I chose a low screen grid voltage of only 120v:. Z 1x12 conv ibanez: 570 custom flame top petrucci jpm p4 3120 ant prestige 7620 gn 505 bm 5 strng bass fender american sienna burst gibson les paul custom brandy. Lucky, 550. My first rig, way back in 1967, was based on this rig. The difference being on the el34's pin 4 is the unused pin (on my last build) and on the 6v6's pin 6 is unused. 8 thoughts on “ Optimization of the 6V6 SE-UL ” Alexis Hernández on March 28, 2020 at 10:34 AM said: Gracias, Gracias Matt, excelente trabajo de laboratorio suficiente como para que Yo intente utilizar mis 6V6 GT que tengo por allí y otros 12AX7 que debo conseguir para el pre-Amp. The 6L6, 6V6, 6550, EL34, 5881, KT66, KT88, KT90, KT100, etc. cathode and grid. Totally Tweed! The preferred OEM tube of '50s-era Fender Tweed Champ and Deluxe amplifiers The Tung-Sol 6V6 has a geometry designed to safely handle the higher voltages used in guitar amps " plus heavier plate and grid materials. Will they survive in the >550-600VDC range? Anyone trusting 'today's' EL 34 of 800 full tilt is a fool. The 6V6 and 6V6-GT are equivalent in performance.
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