12AT7 Tubes

thanks as always everyone

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.

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