Tube question

[AFpay]

Hi,

Could someone please tell me the difference between a 12AX7 and a 12AX7A?
I see these different letters after tube classifications every once and a while and I haven't a clue as to what they mean. Does a 12AX7 sound better than a 12AX7A? Just curious. Thanks.

 

[Bob E.]

The 12AX7A has controlled hum and noise characteristics, so it would be the choice of tube for high-fidelity applications like a preamp line-stage over the non-A. These tubes can be used for many other types of application where the hum and noise would not matter, for example, my Seeburg jukeboxes use one for a pulse amplifier when reading out the selections from the core-memory. My Concertone reel-to-reel tape recorder uses one for the bias oscillator. In these applications, a plain 12AX7 would be just fine.

--Bob

 

[AFpay]

Thanks for the reply Bob. Now to find some 12AX7As.

AF

 

[JHS2RT]

Thanks!!!

I had the same question ---------------My ----The beauty of this forum...It's Priceless !! James:thmbsp: