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December 06, 2022, 08:55:04 AM

Author Topic: Mainline Balanced switch + Tube matching  (Read 245 times)

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Offline PT

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Mainline Balanced switch + Tube matching
« on: March 28, 2022, 04:34:21 AM »
Hello,
Just finished my Mainline kit, got a few questions:

1) There is an audible difference when flicking the balanced switch when using TRS jack. There is zero audible difference when I am using 4 pin XLR, this has been verified by voltage measurement too. Should there be any? I have double checked the wiring everything, seems to be O.K.
2) What is the normal mV difference between L/R channels? I have quickly measured the voltages using 1000Hz Tone, R is 225 and L s 250mV, this was @ 300 Ohm load. This switches 180 when I swap L/R tubes, so must be tube related, right?

Offline Paul Birkeland

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Re: Mainline Balanced switch + Tube matching
« Reply #1 on: March 28, 2022, 04:37:40 AM »
1) There is an audible difference when flicking the balanced switch when using TRS jack. There is zero audible difference when I am using 4 pin XLR, this has been verified by voltage measurement too. Should there be any? I have double checked the wiring everything, seems to be O.K.
This is normal. 
2) What is the normal mV difference between L/R channels? I have quickly measured the voltages using 1000Hz Tone, R is 225 and L s 250mV, this was @ 300 Ohm load. This switches 180 when I swap L/R tubes, so must be tube related, right?
That's a difference of a bit less than 1dB.  It's quite likely that after 100 hours of use, that difference will decrease a bit.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline PT

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Re: Mainline Balanced switch + Tube matching
« Reply #2 on: March 28, 2022, 05:25:09 AM »
Thank you PB,

The difference was not noticed during innitial testing. The amplifier sounds fantastic. I don’t want to get into cheesy descriptions or comparisons, but it exceeds all my expectations and is the best sounding amp I have tried. And ohh I have tried a few.. ;-)