What's the Difference Between Hi and Lo input jacks on some amps?

[MarshallJMP]

The old Marshall 4 input heads have 2 channels, each with their own volume controls. One side is the bright channel, the other one is the normal channel. Each channel has 2 inputs with one low and one high sensitivity (they differ 6db from each other). And the preamp circuit changed a bit over the early years.

[Harley Hexxe]

Richard,

    The model isn't printed on the back of the chassis? That's a bit strange for Marshall.

[Harley Hexxe]

The old Marshall 4 input heads have 2 channels, each with their own volume controls. One side is the bright channel, the other one is the normal channel. Each channel has 2 inputs with one low and one high sensitivity (they differ 6db from each other). And the preamp circuit changed a bit over the early years.

   Yes, the Super Lead 100 I had was like that, Two jacks were marked with "I" and the other two "II" and both were guitar inputs. I didn't think there was a bass input on that amp.

[MarshallJMP]

Yes normally it should say,  super lead, bass or PA on the back. Also the serial nr states what it is.

http://www.superiormusic.com/page024.html

[rnolan]

Erm.. are you sure about the two EL84's?

:facepalm: Fixed

On the back of the chassis mine has a piece of dynotape label that says Lead.  I never knew the bottom jacks were -6db, I thought they were the same.  I've never tried plugging into the bottom jacks, I just ran a short patch lead from the bottom jack of input I to the top jack of input II and plug signal into the top input I jack.  The bright (input I) channel is very bright.

[Harley Hexxe]

Yes, I thought input I was very bright also, and with a Strat in the bridge pickup, it just wasn't meaty enough to cut through.