6eu7 vs 6gu7

Pennk2

Pennk2

New Member
Hey i got a quick question for you guys, I've got an old magnovox console amp that been salvaged but I'm I bit tight on cash and I believe my one of my 6eu7 tubes is going bad. I have a crate full of old tv tubes and I found a 6gu7 tube in it, Is there any way I can use this as a temporary sub or any other tube as a quick fix until I get the extra cash?
Please let me know, thanks!
 
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Pinout is completely different. It won't even light if you plug it in. Not sure what else shares a base layout with the 6EU7 honestly.

Sub options are re-wire the socket to take a 12AX7, or get an adapter to let a 12AX7 plug in. Electrically its the same as a 6EU7, just with the pins all shuffled around.

or you spring for a 6EU7.
 
Thanks for your input I was afraid that might be the case after looking around on the web and finding nothing, thanks again
 
6EU7's in most cases last for many many years. The adapter cost plus the cost of a sub would most likely be greater than the cost of a 6EU7. Like @gadget73 said, best bet is to pick up another 6EU7.

Mike
 
but on the other hand I now know of another twin triode that might be useful for stuff. Looks not grossly different than a 12AU7 or 6SN7.
 
gadget73 said:
but on the other hand I now know of another twin triode that might be useful for stuff. Looks not grossly different than a 12AU7 or 6SN7.
Click to expand...

Yeah, but not only are they nowhere near as common, no one makes new versions. To quote Battradio from another forum..."The 6EU7 was an effort by RCA to sell tubes , it made them and others had to buy the rights to make them , the patent on the 12AX7 had expired". Apparently they are designed like the 7025 to be low noise/low hum, but the 7025 is a drop in for the 12AX7.

More...."A 6EU7 is basically the same as a 12AX7 (same size, same amplification factor, same transconductance, same internal plate resistance) except for two things: the pin-out is different, and a 6EU7 lacks the center-tapped heater of a 12AX7 and so can only be wired for 6v operation."

Adaptors run in the $10 range you know where, or just rewire the socket.
 
gadget73 said:
but on the other hand I now know of another twin triode that might be useful for stuff. Looks not grossly different than a 12AU7 or 6SN7.
Click to expand...
analog addict said:
Yeah, but not only are they nowhere near as common, no one makes new versions. To quote Battradio from another forum..."The 6EU7 was an effort by RCA to sell tubes , it made them and others had to buy the rights to make them , the patent on the 12AX7 had expired". Apparently they are designed like the 7025 to be low noise/low hum, but the 7025 is a drop in for the 12AX7.

More...."A 6EU7 is basically the same as a 12AX7 (same size, same amplification factor, same transconductance, same internal plate resistance) except for two things: the pin-out is different, and a 6EU7 lacks the center-tapped heater of a 12AX7 and so can only be wired for 6v operation."

Adaptors run in the $10 range you know where, or just rewire the socket.
Click to expand...
I'm pretty sure @gadget73 was referring to the 6GU7, not the 6EU7. There are new production 6EU7s being made. No new 6GU7s, though, so you're correct on that count.
gadget73 said:
just thinking it might be a good dollar bin tube. Also shares a pinout with a 6CG7 which is fairly similar.
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The 6GU7 is actually even closer to the 12BH7. The main difference is that the 6GU7 is 6.3v only, while the 12BH7 has a center tapped heater so it can be run at either 6.3v or 12.6v.

I've used 12BH7s but not the 6GU7, even though I have bunch of them, all of which are untested pulls. They must of been used a lot in TVs.
 
yeah, the 6GU7 is the "new to me" tube. Overall just seems like it wouldn't be all that difficult to make use of.

I know what the 6EU7 is, I have an amp with 3 of them.

and yeah I don't expect new are being made of either, but I'm not too scared of obsolete tube types if I'm doing a one-off for myself. In most cases if I picked up a couple pairs of something it would be enough supply to last my lifetime. Once I kick the bucket the next person can worry about it.
 
gadget73 said:
yeah, the 6GU7 is the "new to me" tube. Overall just seems like it wouldn't be all that difficult to make use of.

I know what the 6EU7 is, I have an amp with 3 of them.

and yeah I don't expect new are being made of either, but I'm not too scared of obsolete tube types if I'm doing a one-off for myself. In most cases if I picked up a couple pairs of something it would be enough supply to last my lifetime. Once I kick the bucket the next person can worry about it.
Click to expand...
There are new production 6EU7s, branded Tung-Sol. I assume they're the same as their 12AX7 with a different pinout.

I found a big box of loose pulls at a nearby junk place a while back. I sorted through them and was throwing the 6GU7s into the "unusable for audio" box until I decided to check the data sheet.

I actually love to find "obsolete" types to use in DIY builds or mods. Obsolete, in this case, meaning not currently produced. That covers pretty much all of the tube types ever made. I'm not interested in anything that's close to being unobtainium or expensive.

The SET amp I've got breadboarded uses 26s for inputs and a 6N6Gs for outputs, both of which are long out of production.
 
The 6gu7 is medium mu, cheap and plentiful. The 6eu7 is high mu and expensive.
RCA used the 6gu7 as matrix amps in color tvs which is why there is such a surplus.
 
For the reason regore mentioned (big difference in gain primarily) you will not be able to get a 6GU7 to work properly in place of a 6EU7 in the same circuit. The best advice is to buy another 6EU7, or rewire for 12ax7. Good luck!
 
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