To build on what Fleschler stated, the ECC83/12AX7 has a gain of 100 while the 5751 tube has a gain of 70 which is a decrease of 30%. This means that while the 5751 will probably be less strident and possibly more transparent, your power amp will have to work a bit harder to get the same loudness level as the ECC83/12AX7. Many guitarists substitute a 5751 for a 12AX7 in their amps because they like the mellower sound it produces. Moving along, the ECC82/12AU7 has a gain of about 19 or 20, which means that if you placed the ECC82/12AU7 in the socket that was meant for the ECC83/12AX7, you certainly would hear the difference. By the way, you might want to try Telefunken ECC83/12AX7's, smooth as silk. They are marginally better than the Mullards. Hope this helps.
EAR 864 V1 V3 Tube Type
Can someone tell me the tube type of V1 and V2 in EAR 864? This is what happened, I removed the stock ECC82 and ECC 83 wanting to replace with NOS tubes. When I want to put in the NOS, I realised that there is no printing of tube type beside the tube socket, just V1 and V2 and I have forgotten V1 is ECC82 or ECC83? :(
Thanks in advance.
Thanks in advance.