Placing the value of 15KOhm to the formula for low cut off filter capacitor calculation gives us value of C4 equal to 10uF. Originally Posted by jim p. Needless to say, the 12AX7 is not the ideal drive tube for an output stage. Retrieved 23 May Does an SET amp generally run in class A2? I havent measured exact voltages yet, I computed for the resistor values both for grid 2 of el84 and the RC filter.

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Projection on the axis Va of intersection of the load line and the -8V curve gives us V. In the long run, I concluded that the SRPP with tubes like a 12AX7 was superior pentoed the single ended versions for driving power tubes. I have yet to see a truly high fidelity audio amplifier which benefited from such an arrangement. Now let’s calculate value of C4 in order to hold second grid at AC ground potential. Retrieved 23 May That’s also why we don’t generally use R-C coupling when you want to drive the grid positive; it charges the coupling capacitor eo84 causes strange things to happen which generally are undesirable.

Bugera EL Premium Power Pentode Amplifier Tube EL B&H

You have to use triodes for this sort of PI because the plate current has to match the cathode current. Mon Jan 30, 3: Somehow, the sounds of these breadboarded amps are excellent! The EL84, with an even hotter cathode, would be even better although you would need a better transformer.

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Tue Jan 31, 2: Developed by Philips in for use pentodf the British Mullard amplifier, [ citation needed ] the EL84 came to prominence when used in Watkins and later the Vox amplifiers preferred by many British Invasion bands of the s.

You would have to change one of the resistors ever-so-slightly to make up the difference. Retrieved 25 May The buffer doesn’t even have to be a 6SN7, either. Hi All, I didn’t know whether to get into this discussion or not, but Eliminating a preamplifier triode in radios made them cheaper. Evaluating Gm from the datasheet, by holding anode voltage constant, and measuring the change in anode current for grid voltage, produces value of In turn, the value of C3 will be equal to uF for a 1 Hz cut-off frequency.

A single EL84 was used in low-cost equipment, and a push—pull pair for lower distortion and higher power.

Originally Posted by TS Mon Jan 30, 4: Bottom line the greater the primary inductance of the transformer the lower the frequency response so in simple terms a bigger output transformer will give you more bass response. We select R5 at 56KOhm.

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So this is another reason the triode mode will sound darker. I have also seen this done, pdntode it’s usually with large RF transmitting triodes. Vacuum tubes Guitar amplification tubes.

EL84 / 6BQ5 / 6N14N Pwr Pentode – Tone Tubes

Other equivalent tubes are the and A[4] [5] an extended-ratings version of the tube for industrial applications, E84L long life, professional version with more than hours expected lifetime and the directly equivalent 6P14P Cyrillic: I got the idea from the Legacy amp of Thorsten as well as another project on the net that uses el84 triode strapped to drive a 2a3.

A lower-power triode such as a 12AU7 or 12AT7 might be better but I’d want something with a bit more juice. Fri Feb 03, 8: While not necessarily a true “military version” of the tube in fact it is more comparable to the6P14P-EVs are known for their low noise and durability. This page was last edited on 24 Decemberat If the 2A3 has a positive grid throughout the whole cycle, you’ve successfully built a space heater.

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