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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
apfdirtdoctor
3 responses Add your response
codygrayland
8 posts
 
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
albertporter's avatar
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albertporter
4,949 posts
 
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.
piezo
304 posts
 
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
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