• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

quad el84 or PP el34

Im trying to decide if the pain of going over 400 volts is worth it.

I want to make a oddwatt/simple el84 type setup with a ccs in pp arrangement. However my test el84 setup with b+ of 230,ccs of 83ma for the pair and 7200ohm primaries in pentode mode, wasnt loud enough to drive my dayton reference MTM's with very complicated crossovers.

I figure thats 9 watts of plate dissipation with the current setup. Now the el84 can do 12 watts plate, and i have the nice russian 6P14P-EV on hand. I also have a set of winged-C el34's. The el34 dissipates 25 watts.

So the question is, do i do 2 pair of el84's with half the primary impedance, or do i do a normal el34 setup?

The oddwatt uses 450volts with an 8k primary and a ccs of 125ma. So thats a plate dissipation of 28watts with half the recommended load(??? he normaly does 80% of max plate).
If i just doubled up the el84 and upped the voltage to 300 that would give me about 12 watts of plate, and i would need 4k primaries. So thats about the same power as the el34 setup. But the B+ means i can use way less expensive caps and even some silicon regulators if i want.
 
Hi!

I would not go with CCS in cathodes to drive speakers with complex crossovers. I would use EL84 tubes with fixed bias instead, and local feedbacks by voltage across them.
Either one pair of EL34, or 2 pairs of EL84, the end result will be similar, but less tubes means easier bias adjustment.

Also, 6P41S would be a good option for this case. They are cheap and wide available currently, greatly under-priced. With +140V stabilized screen grid voltage it looks like 2 of EL84 in parallel.

Just my +2 cents.
 
You need more B+ to get the max out of a pair of EL84, say aim for 320V across the tube, that will give a lot more power than 230V B+. Also, if you use fixed bias and a standard LTP or cathodyne phase splitter, that will get you out of Class A into AB for around 15W per channel. Oddwatt is limited to Class A, I built one and liked it, but Class AB will give more power. It depends on your needs/desires in which direction you go.