A question about Valves/ Tubes

[slaytah]

I've got a Bravo Audio Tube Booster (fantastic piece of kit by the way, highly recommended), and I'm looking at alternative tubes to use in it. The tube that's in there already is a Shugang 12AU7.

My question is: What is it I'd need to look at to find a suitable alternative? My flatmate says it's pin configuration, is that right? And if it is, does this mean the number of pins in the tube? The tube that's in there already is a Shugang 12AU7.

 

[MatrixClaw]

The 12AU7 is a standard 9-pin preamp tube, the 12AX7 (ECC83), 12AT7, 5751, etc. will work just fine in that socket, just depends what kind of sound you want. For instance, a 12AX7 will be significantly higher gain than the 12AU7 you have. Doug's Tubes has a wide variety of different kinds, as should any other seller:

http://www.dougstubes.com/preamp-tubes.html

 

[JakeAC5253]

Pinout: Yes
Number of Pins: No

12AX7 and 12AY7 are one family of tubes, and are interchangable
12AT7 and 12AU7 are a different family of tubes, and are interchangable.

 

[slaytah]

Thanks guys, that's very helpful. I'll investigate further, now I know what I'm looking for!

 

[TheWinterSnow]

The pinouts on the 12AX7, 12AT7, 12AU7 are the same, the difference is their performance characteristics, big one being gain and plate resistance as well as power handling and electrode capacitance. In terms of power handling, a very large majority of class A amps run tubes extremely cold even for the 12AX7 which is the lowest power rated tube.

The AX7 will be a bit brighter and aggressive, having more gain/output and the other two will be warmer, the AU7 being really low in gain and a hair warmer which is great for high output and/or bright mics.