High and Low inputs - any tonal differences?

High and Low inputs - any tonal differences?

Postby sclitheroe » Sun Aug 17, 2014 9:48 am

I know, I know - listen with your ears!

But from a theory perspective, I always seek to understand what I validate with my ears, so I'm asking :)

I generally like to use the Normal 2 input on my Bassman, which is the higher impedance input on the normal channel - it has less volume than Normal 1, which lets me get more range of motion out of the volume control, which is useful when you're dealing with a Bassman in the Bassment :)

So the question that I have is whether the two inputs have any tonal differences - looking at a circuit diagram, there's no R/C network at play at all in front of the V1A tube, so this isn't like a volume control in a guitar, where the volume pot has an effect on the treble bleed R/C network, resulting in darker tones as the volume is rolled off. So my amateur-hour conclusion is that using the higher impedance input on the Bassman should have zero effect on tone, only on volume.

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Re: High and Low inputs - any tonal differences?

Postby visserman » Fri Jul 31, 2015 7:38 am

I think you are spot on. I also tend to use low impedance inputs for same reason. On some amps you find toggle switches which do say "Low/High" and it is simply the same idea as having two separate inputs for low and high imp.

Modern amps tend to have one input, I think people no longer feel that humbucks should be put into a low input to achieve clean sounds. Just a sign of the time.......................
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Re: High and Low inputs - any tonal differences?

Postby zentropa » Fri Aug 07, 2015 9:59 am

When I bought my first tube amp ('68 Twin Reverb) I was told input 2 was just 15db lower than input 1. Not sure if this was actually true or not but ended up running through input 1 if I wanted to try to get it to break at all and input 2 for more clean headroom. Never noticed a tone difference, more of a change in the amount of push.

High gain tube amps tend to behave a bit differently on this end though.
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