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U67 any sonic differences between 117v vs 127v
Old 3rd December 2014
Lives for gear

U67 any sonic differences between 117v vs 127v

I was wondering if there would be any sonic difference between 117v vs 127v settings for a Neumann u67 and what would be the optimal setting for the USA where the nominal voltage is 110/120
Old 3rd December 2014
Lives for gear
Marcocet's Avatar
Assuming it's an adjustable power supply, either one should work as long as you adjust the outputs to be correct with a load attached and you don't switch from then on. Normally people would use 117 in the US.
Old 4th December 2014
Gear Maniac
Warren Beck's Avatar

NO difference what so ever. The psu regulates the voltage to what the microphone wants to 'see'. The psu's were made to accept a range of voltages. In the US voltages ranged from 100 - 120v - so the components chosen considered that spread.

Any potential of sonic difference form the given supply voltage, would be after the regulation/filtering of the PSU. IF you starved the plate in the tube - it would give you a different "tone" than if you gave it some extra voltage. But that can damage the capsule and other bits. It is not like sticking a Marshall amp on a variac and turning the supply voltage down and getting the Van Halen brown sound.

As mentioned above if it is a source selectable supply - choose 110 or 120 for North American use.

Pictures can help as well in getting a more specific advice!!
Old 4th December 2014
Gear Maniac
Geetarpicker's Avatar

I just looked at the schematics of both a U67 and it's power supply. It appears to me the filament circuit is perhaps regulated by a zener diode circuit, but the B+ sure appears unregulated to me. Tubes definitely can sound different depending on the B+ levels. Personally I think my pair of U67s sound a little better to my ears running at 127v settings, which would net a slightly lower B+. Anyway my preference might have something to do with the wall voltages around here, which can be close to 125v on average. It would seem to me running the 127v tap is a closer match to my wall voltage than the 117v tap. We are not talking a huge difference in voltages either way, so perhaps try both and see what you hear.
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