EZ8O, EZ81, & 6BW4 Rectifier Differences?

[zozoe]

Hey all,,, There's an amp with 2-12ax7, 2-EL84s, and the option of any of the 3 rectifiers choices in the header.... I realize rectos don't really affect tone, but which one would be best for this setup, & offer more gain to the circuit? And why?
Best regards~

[thetragichero]

6bw4 seems the winner based on brief viewing of data sheets
less heater current (these all seem to be 6.3v fundamental tubes), more current capability. seems to be around the same 40v voltage drop
edit: if you're looking for max voltage and stiffer supply solid state rectification would be the way to go

[zozoe]

Yeah, I want a max OD circuit, & sag is ok. 6BW4?
Thnx

[EL504]

The EZ81 (= 6CA4) has way more (about 1.5 times) current capability than the 6BW4 and EZ80.

The EZ80 and the 6BW4 would run near their limits in an amplifier with 2 x EL84 pp at Vb = 300 V.

So I would choose the EZ81.

[ChopSauce]

Yes, the EZ81 is what Vox used for pretty similar configurations.

[xtian]

Yes, EZ81. But you likely don't want higher voltages. Old equipment runs hot on today's 120vAC wall voltage, and we're often looking for ways to cool them down! The heater voltage is usually pushing 7v in these old amps (if we're still talking about 60s Bogen).

Another way to look at it: Higher plate voltages will get you higher headroom and later breakup. Lower plate voltage gets you distortion earlier, at lower volume. And if you're playing at home, that's usually what we're after--lower volume, more distortion.

[thetragichero]

just for my own knowledge, did i misinterpret the "per plate" figures in the 6bw4 data sheet m was i not supposed to double them?

[EL504]

Yes, you are supposed to double them if the graphs you are looking at are valid "per plate".

[thetragichero]

this could also be what i get for trying to read 80 year old datasheets at 1am in the dark
i almost always use a strong of 1kv fast recovery diodes anyway. MOAR POWER