my question is this, I've always enjoyed tracking down the various tubes that will work in my amps/preamp and this one will not be any different. I picked up some SV83's and some 6P15P's, I have an old pair of EL84's but I discovered several places that say EL83's are the same as the SV83's. I just happen to have a lovely NOS pair of Tesla EL83's. I looked at them and they do not appear to be the same as the SV83's. Can anybody clear this up for me please?

Thanks!