Should I not use any external 48V power supply with my V72, or it will damage the input-transformer?

I should not use any external 48V power supply with my V72, or it will damage the input-transformer? Or were you talking about a PSU [Power Supply Unit], which is wired inside the V72, to the input?! Is it possible to use units like the Sennheiser or Audio Technica 48V-supplies? If not, I have to use the circuit you posted?!

For each V module you need a separate +48V ramped circuit (that can be feed from a main supply), sure most V units make it about a year or so without, but as soon as you hear slight crackling, loss of low and/or high end, you have a compromised input x-former. The circuit posted works quite well, is fairly cheap (about $5 in parts) and also takes care of the nasty pop you get if applying +48V. To be precise you need a at least 55V supply so the regulator works properly.

I had several heated arguments with hard core EE that +48V is absolutely save, etc. , but that again everybody send me the broken stuff as soon as it breaks for rewinding and complains about the cost. Take some time for preventive maintenance....

Please take a picture of the broken V72 input, didn't made the historic insulation test of 500V. The customer had the unit for years and a month after he applied + 48V the units lost all bass and got noisy. Aside the compromised input, the EF804S was toasted as well.

Best regards,

Oliver

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