6CA7 in an EL34 build.

[ViperDoc]

I see in my research that 6CA7 power tubes are swappable with EL34, the effect being some potential added bass. In a high gain Marshall, is this a straight swap given some potential re-biasing, or should anything else be considered to get the most out of them? Thank you.

[martin manning]

Yep, just plug it in, man.

[Stevem]

Your really not going to get any added Bottom assuming the EL34 your swapping out is in good condition,but what you might get is more clean head room before the output tube starts to clip which can make the bottom end fart out.
There are a few ways to tighter Bottom end you need a higher wattage amp, more speakers or more efficient speakers and more filterning in the amps power supply can help.

[ViperDoc]

By more filtering do you mean additional can caps or say, if you're using stock dual 50 uF caps, you go to 100 uF?

[pompeiisneaks]

By more filtering do you mean additional can caps or say, if your using stock dual 50 uF caps, you go to 100 uF?

Yes, but if you're using a tube rectifier, be careful of going too high with filtering near the tube rectifier. If it's solid state it's not a worry. Dumble ups filtering in most of his amps from common expectations very often to give it a more solid power supply, etc.

~Phil

[wpaulvogel]

EHX 6CA7 have more bottom end than any EL34’s I’ve used. I have used old Mullard, RFT, winged C, and current production. The 6CA7 will be down a few watts than the EL34’s though. I like their sound.

[Roe]

the old sylvania 6ca7s sound a little stiff, tight, clean and hard compared to ordinary el34s.

[statorvane]

EHX 6CA7 have more bottom end than any EL34’s I’ve used.

Ditto. I really like them. Prefer them to any new production EL34/KT77.

[Thermionic/EL-34]

6CA7 is the USA designation for EL-34
EL-34 is the Euro designation for 6CA7.

12AX7 is the USA designation for ECC-83
ECC-83 is the Euro designation for 12AX7.

And so on. All on the internet.

[didit]

In original issue 6CA7 was a beam tetrode/pentode, so similar in design to KT77. Fits in socket well with differing detail in behaviour. Or so the story from Sylvania & GE goes.

Best .. Ian

[Thermionic/EL-34]

In original issue 6CA7 was a beam tetrode/pentode, so similar in design to KT77. Fits in socket well with differing detail in behaviour. Or so the story from Sylvania & GE goes.

Best .. Ian

Sylvania did that so they wouldn't be sued by Mullard Blackburn Works LTD & Amperex.

[didit]

In original issue 6CA7 was a beam tetrode/pentode, so similar in design to KT77. Fits in socket well with differing detail in behaviour. Or so the story from Sylvania & GE goes.

Sylvania did that so they wouldn't be sued by Mullard Blackburn Works LTD & Amperex.

Yes. Most everyone did. Now including today's EHX 6CA7, though not for patent reasons. Point being, large percentage of tubes marked 6CA7 are beam-based despite equivalence/substitution specifications. Only occasionally see tubes with 6CA7 marking that are obviously screen pentodes.

Best .. Ian