Plate voltage el34. May 26, 2023 · An EL34 with 400V on the plate and 62.

Plate voltage el34 EL34 datasheets show full-signal screen current around 25ma per tube for voltages like this. 001 for a measured 1mV across the 1Ω), and you'll find your idle dissipation. 5w out 400v DC 130 mA 142 mA 220 ohms 5000 ohms 16. May 1, 2017 · Hi. 0588 = 21. EL34 triode mode connection. My recommended bias measurement method is the " Output Transformer Resistance Method. Jul 7, 2018 · Does anyone know what the plate voltage is for an Archon 50? I'm installing El34's. The EL34 datasheet provides detailed information about parameters like plate voltage ratings, grid voltage limits, and transfer characteristics. Alternatively, 440V self-bias suggests 7K (or 6. 5 watts 3% Hoffman Amplifiers Tube Amp Forum, High OR low plate voltage question Jan 7, 2021 · That's because the EL34's Gm is very much higher (around 11mA/volt rather than ~5-6mA/volt), and much less bias-voltage is needed at G1 to tame plate current. EL34 penthode mode connection. The lower measured quad The SvetlanaTM EL34 is a glass envelope power pentode having a plate dissipation rating of 25 Watts with convection cooling. operated or Jan 19, 2022 · I reached out to TAD about what EL34's they'd recommend for an amp that sits around 520V at the plates w/the screens around the same. 0588 394v - 28. The safe operating area is also shown, bounded by the 25W max plate dissipation curve. Multiply the two measurements (being sure to use 0. TAD – EL34-SVT High Performance Audio Beam Power Pentode The TAD EL34-SVT is manufactured in the Svetlana factory in St. These specifications help designers comprehend the operational limits and the behavior of the tube under various conditions. 7/244. Then there is an easy math formula to compute which will tell you what your bias setting Feb 5, 2021 · I wanted to try some EL34 output tubes in my KT88 amp (running as UL/OT screen tap) but I think they are running too hot checking the voltages. 2=. The tube can stop the flow completely (called cutoff) or let it flow at maximum (called . It says -42 to -48 on the schematic. The Renegade has about 460-470 volts dc. Does anyone know the recommended bias point for El34's? Tube charts say 375 VDC plate volts for EL34 cathode bias. That means you’ll need to take measurements of your plate voltage with either a multi-meter or buy a bias probe. ? So where am I wrong here, and why the difference with pin 1 tied to pin 8. Some guitar amps go over 500 volts. You use your pate voltage to determine how much current draw in an amp versus the tube wattage dissipation versus plate voltage. Petersburg, Russia, and is designed to be a direct replacement for any EL34/6CA7 or equivalent. You actually lose more voltage across the screen resistor if you're in class AB or B, since 25ma average is (potentially) 50ma for half the cycle and 0ma for the other half. GENERAL This valve is a high slope output pentode designed for operation in A. both the grid voltage and the plate current on all amps are set to the supply volltage , what is on the data sheet is not always what you find in a actual amp. For amps with cathode bias resistors you can simply measure their voltage drop and use the Tube Dissipation Using Cathode Resistor Voltage Drop calculator. An amplifier tube controls the flow of electrons running through it. (EL34's max out at 800VDC, so 375 is rather low. Nov 27, 2006 · It could be measured by inserting a current meter is the plate lead of the tube but this is dangerous because of the high voltage. I have seen spikes over 2KV in a typical 2 X 6L6GC on 430 volts guitar amp output stage running into a 12 inch guitar speaker at 95 Hz, it's resonant frequency. Jul 5, 2006 · Most HiFi amps run the EL-34's anywhere form 350 to 450 volts with a few higher. One of the reasons SED EL34's are known as so robust, is the 500v rating on the screens. The EL34 tubes caused the B+ to go up a bit, and while I don't see any red plate after playing for about an hour, not sure they will last long running As for the New Sensor's EL34 range, I won't run them in any amp over 420. It sounds good to me set at -42 Some one definatley was in this amp The way I set bias is the shunt method , I first check the plate voltage to know where I want to adujust the grid voltage ( the negative 37 or negative 57 volts you speak of) to get the proper plate current (the 28mA or 42ma you speak of). Guys just to seek your opinion of EL34 measured from pin 3 & 8 having a plate voltage of 290V biased at 46mA. Cathode bias requires the correct supply voltage -- usually rather low, in order to maintain bias. It will get louder set at -34 but then the plate voltage drops to like 390+-. Bias current is the amount of electrons flowing from the cathode to the plate with no audio signal on the control grid (idle current). It sounds good to me set at -42 Some one definatley was in this amp Funny how these run in cycles. The same effect happens on a smaller scale with various 6L6s or various EL34s: The ones with higher Gm don't require as-large a bias voltage to tame their plate current. EL34 ultralinear mode connection. Biasing Tube Amplifier Calculator Use this calculator to determine the bias current for an amplifier’s power tubes. Which is probably about where it is with a 270 ohm cathode resistor. 11753/2=. It is intended for audio frequency power amplification service in either pentode, ultralinear or triode connection and single or push-pull/parallel applications. High Performance Audio Power Pentode SvetlanaTM EL34 is a glass envelope power pentode having a plate dissipation rating The of 25 Watts with convection cooling. If you need more information on biasing your Granger amplifier, please contact us. If you bias the tubes to idle at less current, you're applying more-negative voltage. Most power tubes were never designed to What is Bias? Bias voltage is the voltage difference between a tube's cathode and control grid. Up until now I have made the assumption that the plate current is equal to the cathode current. Jan 2, 2014 · I can measure plate voltage with tube out/off (EL34/KT88 pin 3-pin8) and I can estimate plate voltage a little bit lower (example if I measure 450V WITHOUT tube, estimation of 430-435V as palte voltage). . Aug 11, 2025 · I have two quads of the Psvane Legend EL34-PH tubes, supposedly their best production EL34 type tubes One quad's plate voltage measures ~28 mA and the second quad measures 45 mA. I did notice that when properly biased, there is a very subtle difference in the sound. Jan 4, 2002 · It doesn't have to be that way: screen voltage sets the maximum plate current the tube can pass. How to Measure Bias This webpage offers two ways to calculate tube bias and plate dissipation. May 30, 2020 · Changing the tubes of a Marshall JCM900 (EL34) Tubes are easy to change but you absolutely need to bias them once installed (power tubes). 3v 365. I settled on 435 VDC plate and -42 grid VDC. 3v x . For this reason, if running a single ended EL34 at 100%, the screen voltage should be around 50-60V lower than the plate voltage (to keep the load line through the knee of the Vg0 grid curve), and you should have a 1k-2k Rg2 (to eat up excess screen current under big signal swings). Fixed bias allows for correct bias at higher plate voltages. Tubes like the 6550/KT88 can deliver all the plate current they can manage with a relatively low screen voltage. Aug 11, 2025 · Plate voltage is a function of the tubes' current draw on the power supply. But different static dissipation levels may sound different. 47 dissipation (watts) Obviously, the g3, pin 1 on EL34 tied to cathode affects the tubes plate voltage. Enter the plate voltage and type of power tubes to get the bias current at various levels of plate dissipation. But when designing voltages for bias supplies, a good rule of thumb is that the bias voltage should cover a range +/- 10% of the plate voltage. Like others said, the screen voltage is the determining factor. May 26, 2023 · An EL34 with 400V on the plate and 62. [1] The EL34 has an octal base (indicated by the '3' in the part number) and is found mainly in the final output stages of audio amplification circuits; it was also designed to be suitable as a series regulator by virtue of its high permissible voltage between If I use 394 plate voltage (pin 3 to Ground), instead of 375v 28. Push-pull class AB1 triode connection, cathode bias Plate and screen voltage Plate plus screen current, idle Plate plus screen current, full power Cathode bias resistor, common Load resistance, plate-to-plate Output power Total harmonic distortion at 16. 4K load in self-bias with EL34 works out to about 300V of safe B+ plate-to-cathode, say 340V from OT to ground. The TAD EL34-SVT / SvetlanaTM EL34 is a glass envelope power pentode having a plate dissipation rating of 25 Watts with convection cooling. 5mA plate current, is right at the EL34's maximum 25 Watts plate dissipation rating. Funny how these run in cycles. The Svetlana EL34 has an indirectly-heated oxide cathode, which may be DC operated for the absolute best hum Oct 20, 2018 · What happens when the amp's plate voltage exceeds the tubes' rated plate voltage? Let's say I plug in a tube rated up to 400 volts into an amp that has 450 volts plate voltage? Is there a way to mitigate plate voltage via tube bias? 3. I don't know the exact screen reading, but it's on an older modded Marshall and I've always heard Marshall screen voltages tend to only be a few volts below the Mar 4, 2014 · Due to the lowish VB+ and high (for an EL34) OT primary impedance, the EL34 won't benefit (in terms of class A clean output power) from increasing the static current / plate dissipation past a certain point. Sep 10, 2025 · The chart below illustrates a typical set of plate curves for an EL34 with a 4kΩ load line originating from a 400V power supply (B+). These guitar amps (the old Marshalls come to mind) tend to eat up tubes rather quickly due to the high plate dissipation that they run. Sep 17, 2018 · Otherwise you can easily over-dissipate the screen. My bias resistor was 56K with a 220K in parallel. Mar 17, 2013 · Len,plate voltage is the voltage on the plate of an output tube. So seeing as how you report 450V on the plates, I'd aim to have a bias voltage adjustment that covers -45V to -50V. The EL34 was introduced in 1955 by Mullard, which was owned by Philips. The max range i could get was -44MA. 6K) load. But note that at 800 pate volts, only 400 for the screens. Measure the millivolts across the 1Ω resistor. Is it too low? Tube type: Amp class: Plate voltage: VDC Bias current for one tube: mA Note: This calculator is intended for quick reference only. The Svetlana EL34 has an indirectly-heated oxide cathode, which may be DC operated for the absolute best hum Can any one shed any light on the relationship between screen voltages and plate voltages in a power tubes (say 6V6)? How does altering the voltage difference between these two structures affect tone? How does it affect power? How does it affect the safe or optimal operation of the tube? Any guidelines or explanation of principles would be greatly appreciated. Now, Either change the quiescent plate volts to 500V, Or change the plate current to 80 mA, and you are running the EL34 Too Hot! Mar 30, 2022 · Your Plate Voltage has no bearing whatsover on you bias range, as I said your bias range should read -34 to -40 for EL34's in a 50 watter. Significant deviation from the designer's intention means the tubes aren't drawing the correct amount of current. Thanks The way I set bias is the shunt method , I first check the plate voltage to know where I want to adujust the grid voltage ( the negative 37 or negative 57 volts you speak of) to get the proper plate current (the 28mA or 42ma you speak of). C. " You measure the output transformer's voltage drop and Jul 20, 2020 · The plate voltage can spike to a large negative voltage on the previously conducting tube, and a larger positive voltage on the nonconduction tube. An EL34 has a plate dissipation rating (Pdiss) of 25w. To find out what your EL34 is actually dissipating, measure voltage from EL34 plate to cathode. ) I suspect that at 500+ plate volts, good cathode bias may be a Jul 25, 2017 · The plate voltage and plate power dissipation are related to the load, in as far as power requires a certain load to work into in order to stop the tube burning itself up. The Svetlana EL34 has an indirectly-heated oxide cathode, which may be Preferred Series EL34 Specifications: Filament Heating …………………………… ………………………………Preferred Series EL34 Specifications: The EL34 is a thermionic vacuum tube of the power pentode type. he Svetlana™EL34 is a glass envelope power pentode having a plate dissipation rating of 25 Watts with convection cooling. 11753, . That is what fails (90% of the time) on power tubes. Need a bias probe? Order our bias probe from the Custom Shop. 7v= 365. Also real KT77 have a high plate impedance than EL34's more like a 6L6, but who knows with the JJ tubes, they aren't exactly 100% real KT77's anyway. Always refer to the manufacturer’s tube datasheet for absolute values. We forget that output tubes provide voltage amplification to their plate (because we typically focus on plate current and how that interacts with load impedance to cause the plate voltage variation). 6lxo w36c jj tlo99 1lvj zq5 h7g5v smb9 blocrxs vqs