VTL 75 75 deluxe amp...... Input/Driver tubes????

I purchased a VTL 75/75 Deluxe power amp serial number 7575022 and it came with 4 12at7 input/driver tubes. (output tubes 6550Cs). Some have suggested 4 12bh7s others have said 2 12at7s as input tubes and 2 12bh7s as driver tubes....others have said 6414 driver tubes. HELP!!! does any one have a copy of the manual. VTL has not answered emails. Thanks Larry Unruh
Hi Larry,

VTL recommends 4x12AT7's for input and 4x6550's for output. It has been suggested KT88's can be substituted for the 6550's. I will be trying this experiment sometime during the summer after sending(and receiving back) my 75/75 Deluxe to VTL for the bias-point addition mod.

Cody Grayland
12BH7 may work in that circuit, it is designed with similar parameters as 12AU7 and 12AT7. I used 12BH7 in my Air Tight ATM3's and got a huge upgrade.

If you want to play it safe, score some Telefunken 12AT7 off EBAY, plug, play and be prepared for a huge sonic improvement with no risk or downside.
i recently installed mullard NOS 12at7s in my mb185s (from upscale audio)at about 35 a pop. substantial improvement everywhere. stick with the 6550s and try the winged Cs. they are very well balanced