12AT7 Tubes

as far as hurting anything goes the 5751 and any of the 12-7 are drop and play just as Mechans says. These changes may affect how things sound however. In guitar amps the pre amp tubes, especially the first gain stage are often swapped out to affect how much clean headroom the amp has before breakup. the lower gain preamp tubes hit the power section easier and give you more head room. due to power section design in a hi fi amp breakup probably isn't and issue

In my circuit I can sub any 12--7 for the original 12AT7s. You should never just drop in a 6922 type unless the manfacturer has made a provision for that switch over. The 5751 is a lower gain 12AX7. They may notprovide the gain you want or need for your phono stage if you have one but since the 12AT7 has the lowest gain of the more common 12volt dual triodes it might be OK. It would be indecent of me not to say if your pre can handle them that they are a great choice.

thanks as always everyone

Chad - I used to own and enjoy the SFL-1 preamp. It came stock with a 12AT7 tube, but there was a jumper that could be moved that would allow you to use a 6922 tube. At the time, the designers prefered the sound of the 12AT7 tube. To my knowledge they never suggested that a 12AX7 tube was to be used.

thank you very much

Chad, I probably pointed you towared this question from my answer in another post. As I recall (and I do 'think' I'm correct because I was looking at pre-amps at that time already being a SF amps(s) owner. When the first model of the SFL One came out in the early 90's in a review in Stereophile as I recall said it had the option (by using an internal switch) to change between the 12Ax7 and 6922. Apparently in later editions this must have changed to just the 12AT7. I guess you sould just check your owners manual, a schematic, or pop the lid and check for yourself. Sorry if I caused any confusion.

Hello Chad. The 6922 will not work at all, and the 5751 will probably operate in the circuit but I sincerely doubt it would sound right. There are many appropriate electrical subs for the 12at7 such as the 6060,6201,6679,7728 or nos euro tubes like the B152,m8162, ecc81. The american 12av7 and the 12az7 will also sub for the 12at7 in many circuits. cheers David