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Discussion Starter #1
How much effect do they have, exactly ?

I'm aware of the different gain factors as listed at the tubestore, but what real-world differences will subbing a 12AU7 (gain factor = 19) for a 12AX7 (gain factor = 100) have ?

Any brand recommendations for:

12AU7

1212AV7

12AY7

12AT7

???
 

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I actually ordered a few types to experiment with this as well. One thing others have told me is that while it can affect the gain level, it can also affect the overall volume of the amp.

EG., I am going to try a 12AT7 in my Champ clone. People have told me while it will increase the headroom, it will also lower the volume of the amp though.
 

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Electric I said:
How much effect do they have, exactly ?

I'm aware of the different gain factors as listed at the tubestore, but what real-world differences will subbing a 12AU7 (gain factor = 19) for a 12AX7 (gain factor = 100) have ?

Any brand recommendations for:

12AU7

1212AV7

12AY7

12AT7

???
Subbing a 12AU7 will reduce the gain significantly and I personally wouldn't recommend it. However the 5751 and 12AY7 tubes are a nice substitute if you want a cleaner sound.
 

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Discussion Starter #4
torndownunit said:
People have told me while it will increase the headroom, it will also lower the volume of the amp though.
That's exactly what I'm looking to do. I figure if i need more gain/od/dist I can always goose the front end with a pedal or two. Thanks for the input.
 

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Discussion Starter #5
Scottone said:
Subbing a 12AU7 will reduce the gain significantly and I personally wouldn't recommend it. However the 5751 and 12AY7 tubes are a nice substitute if you want a cleaner sound.
True enough. Thing is, I've tried a jan/phillips 5751 & it didn't seem to do a whole lot.

Any brand of 12AY7 you'd care to endorse ?

Thanks
 

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Electric I said:
True enough. Thing is, I've tried a jan/phillips 5751 & it didn't seem to do a whole lot.

Any brand of 12AY7 you'd care to endorse ?

Thanks
I don't remember the one that I was using in my Pro Junior, but it was something recommended by Lord Valve. Looks like Jeff is recommending the RCA, so might as well start there.
 

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Always an exception...

Just FYI, the 12AU7 doesn't like to just be plugged into a 12AX7 socket.

It works after a fashion but unlike the other tubes mentioned it doesn't like the usual 100k plate resistor value. It would rather see maybe 47k or even less.

So by just plugging it in you aren't really giving it a fair shake. If you like it ok but if you don't it may be because it needs the resistor changed.
 

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V1 position

I have been experimenting with various tubes in my Victoria 20112 and find the 12AV7 a nice option for V1. It came with a Sovteck 12AX7 in V1 (very
harsh sounding) and I replaced it with an expensive NOS RCA 5751. This tube warmed things up quite nicely but the (way less expensive) 12AV7 sounds way better IMHO. I also like the Sylvania and Rogers 12AX7's in
this position and have a 12Ay7 on order to experiment with.
 

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With Tweed amps like a champ,it is better to try a different rectifier tube.Try using a 5V4 or 5AR4 in your champ.It will give the amp more punch and slightly improve the clean headroom.
As wild bill said,the 12AU7 requires a different plate resistor to work in it's intended range,but it is a very worthy sounding tube just plugged into a Tweed Deluxe.Try it.You will like it a lot.In some amps it does not sound right,but Tweed amps are simple to start with and they will sound good with the 12AU7 in V1.Been there done that many times with great results.They suck all the volume out of a champ though.:rockon2:
The 12AY7 was a very common tube in Tweed era amps.A 5751 can be a really nice sounding tube too,but the gain is not much less than a 12AX7.
I prefer a 12AU7 in V1 on my Tweed Deluxe for cleaner blues.
 
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