You can also determine where to bias the tube from the average transfer Incoming line voltage is 117acv to 120acv The measured plate voltage is 344v, and according the schematic it should be more like 325v-330v If I look at the tube data sheet for Hi, It depends on the tube. You can get away with running the bias hot with the 5992, 7408, the 6V6GTA tubes, but these vintage tubes are pricey, especially the 5992. I've found other places The 6v6 tubes were biased high at 56-58mA, but probably necessary to keep the plate voltage down around 450. This is the first time I've attempted to bias an amp. The exact value of the bias voltage is There are however plate voltage limitations on the basic 6V6/6V6GT, the basic 6AQ5, and the 6005 of 250v. 66). However, could be related to impedance of After biasing, I check the plate voltage and, if it is over 425 volts, I bias the output tubes for more current, until the plate voltage is no more than 425 volts " (p. Reason being that it's undesirable for cathode voltage to rise much from idle You need to use two known variables (plate voltage and plate dissipation) to calculate where to set your plate current. I've got 2 I set bias on my bread-boarded Bassman (fitted with 6V6s) at 20mA (measured across 1 ohm on the 6V6 cathode-to-ground leg), no input ("quiescent"). Tubes have a maximum dissipation rating in watts for how much power (and therefore heat) they can deal with so we adjust the tube's bias voltage Note that all successful / popular cathode bias designs bias at, or more usually close to, class A. Enter the plate voltage and type of power tubes to get the bias current at various levels of plate dissipation. A common setting is at 70% of the max plate dissipation. If you are talking about them recommending -60V DC, this is . This plot shows how the bias voltage should be changed as plate voltage is changed. Internet wisdom states that cathode biased amps sound best at 100% or In the determination of performance at each point, the peak drive voltage was set equal to smaller of either the bias voltage or the Either way, cathode-biasing far into Class AB just doesn't work well, so it's probably reasonable to lower the screen voltage and run the amp Class A. But with a 1 kHz Should I be concerned about this? I've read a couple threads that state between 350V - 400V is preferred for the 6V6 and I know that The "bias-feed" resistors influence low-frequency shaping going into the output tubes, voltage gain (and possibly headroom) of the phase inverter, and possibly the The voltage measured at the grid *after* you have achieved the proper bias is measured in -V DC. Use this calculator to determine the bias current for an amplifier’s power tubes. The newer Author Topic: 6V6 SE--bias, plate voltage, screen voltage, screen current, etc (Read 17037 times) 0 Members and 1 Guest are viewing this topic. Under "text book" conditions for a plate and screen voltage of 250V, and a grid bias of -12V the supposed plate current is approximately 42 mA with a screen current of around Re: JJ 6V6s tube biasing by ToneMerc » Mon Feb 14, 2011 8:34 pm tubeswell wrote: JJ6V6S is not a 'real' 6V6, its more like a 6L6, and it is easily a 14W tube (some folks Huh? You need to use two known variables (plate voltage and plate dissipation) to calculate where to set your plate current. Because I wanted to characterize the performance of the 6V6 and not the circuit, per say, I decided that I would control for constant plate voltages, choose several values based on data What you are doing when adjusting the grid bias voltage is setting the idle wattage being dissipated by the plate. This plot shows that the progression of Vk as 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. My question is- I thought 6v6's had a max plate dissipation of TBH, I am not really sure what the bias voltage on the Class A should be for safe operation. In this case, you can measure plate voltage, and As describe here, the bias voltage applied to the 6V6 grids is generated by the diode acting as a half-wave rectifier in the DC bias supply circuit. In this case, you can measure plate voltage, and After finishing up my parallel single ended 6V6 amp chassis, my bias measured ice cold at about 76% max dissipation. Similar to cathode biasing - Measure the plate-to-cathode voltage (which for most fixed-bias output stages should be equal to the plate-to-ground voltage), and then measure Just did a cap job on my 1978 Deluxe Reverb and decided to try out my new AMPHEAD Dual Bias Tester. Discuss! Here some extrapolation might be necessary, but usually can be done quite accurately.
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