Found some NOS tubes...need some advice

[Tome of Demise]

Ok, so i found some NOS 12AU7's in my grandfathers box of tubes (he has a ton of different NOS tubes for his ham radios)

The tubes are GE 12AU7 and a Silvertone 12AU7. Can someone tell me a bit about these and if i can use them in my Boogie Mark III ?

Thanks

 

[ylo]

12AU7 is a medium mu triode. The gain of each side is lower than 12AX7, so you will get less volume at the same knob settings and probably a mellower sound.

Some people prefer 12AU7s over 12AX7 in the Vox Tonelab pedal and in other tube stomp boxes, for example the Ibanez Tube King.

Note that the two halves of the 12AU7 are not the same gain.

The Silvertone is a rebranded something, probably an RCA or Westinghouse.

You may find a use for one or two of these if wear is relatively low, but you will probably prefer 12AX7s in your amps and stompboxes in almost all positions that call for 12AX7s, which is most positions.

 

[Russ]

Check this out:

http://thetubestore.com/gainfactor.html

I hope this helps. It is the easiest explanation to digest that I could find. Chances are that you will not be using those 12AU7s. I have some, even the clear top RCAs that are a preferred 12AU7 type, but have no use for them. I had an old organ that would have loved them though. It is long since gone now but I kept the tubes anyway.

You might be able to use them as trade stock to get some 12ax7s from someone or even some 6L6s.

 

[Tome of Demise]

Thanks for the helpfull replies guys!
Now if i can only find someone willing to do a trade. I'm in desperate need of new preamp tubes :idea:

 

[Russ]

Just be careful if you are not fully knowing what you are getting. Many people will test their tube stock but don't calibrate their tesing rig often enough or at all. Beware of the slick guys on E-bay with the bait and swap or the ignorant ones. You might be able to get a fair trade with some of the NOS vendors though but you will have to search them out because no respectable NOS vendor would be selling on E-bay.

 

[Tome of Demise]

Just be careful if you are not fully knowing what you are getting. Many people will test their tube stock but don't calibrate their tesing rig often enough or at all. Beware of the slick guys on E-bay with the bait and swap or the ignorant ones. You might be able to get a fair trade with some of the NOS vendors though but you will have to search them out because no respectable NOS vendor would be selling on E-bay.

I appreciate the heads up

 

[Timbre Wolf]

Note that the two halves of the 12AU7 are not the same gain.

This is incorrect - I believe you are mistaking the 12AU7 for a 12DW7 (or 7247), which is half 12AX7 spec. and half 12AU7 spec.

- T

 

[Russ]

:wink:

 

[ylo]

Maybe I spoke to quickly. According to a widely circulated RCA data sheet, the two sides are the same.

I have another data sheet, GE I think, that gives a lower mu for one side than the other. Anyway, this probably would not be significant for preamps.