Low input vs. High input

[korovamilkdud]

I've only recently noticed the difference between the two in terms of EQ. I always thought that it was just a change in gain, but the Low sounds quite a bit warmer than the High in my amp.

What would account for this? Is this a power tube vs. preamp tube issue?

Just curious.

 

[Andrew Lamprecht]

Re: Low input vs. High input

I'm curious too.

 

[astrozombie]

Re: Low input vs. High input

ive read in manuals thats its just an input that takes your signal and subtracts some db

 

[Kam]

Re: Low input vs. High input

This just reminds me that the high input on my AOR hasn't worked in years. I gotta get that sorted out.

I can't wait until someone who knows what they're talking about gets here...

 

[Van Noord]

Re: Low input vs. High input

As far as I know the difference is just the reduction of db's. Typically 6 db's, which is significant in the world of guitar. That much of a reduction can put a real spin on your tone and will affect it in more than one way.

I use the LG input on my GH50L, as I find the amp sounds smoother, less harsh and less bright. This may be because the input preamp tube isn't getting slammed as hard as when using the HG input. Dunno.

Also, sometimes we designate things we hear as something they are not.
We are all guilty of that.
So hearing a lowered boosted input signal may be described as less treble, or more warmth, when it is in fact simply just less input gain causing that perception. shrugs

 

[Jeff_H]

Re: Low input vs. High input

I don't know the technical reasons behind the difference in sound, but I've always heard people refer to the high input channel as the "treble" channel, so I've assumed that there is something in the gain structure that, in addition to adding gain, also adds some treble to the circuit. Whether that is true or not I have no idea.

 

[JumpMarine]

Re: Low input vs. High input

I don't find that the Hi input on my Maz Jr adds anything to the eq, other than a 3db boost and a bit more push on the front end that breaks up earlier.

 

[korovamilkdud]

Re: Low input vs. High input

It's a mystery.

 

[sbecker67]

Re: Low input vs. High input

I've never noticed any change in EQ, just in volume. I'll typically use the high input channel for single coil guitars and the low for humbuckers; seems to balance them out a bit and gives a little more clean headroom with the higher output buckers.

 

[uOpt]

Re: Low input vs. High input

Different impedance would cause this. If the input is -say- 250 Kohm versus 1 Mohm that would combine with the resistance of your volume pot for a higher load in the former case. This load lowers the amplitude of the resonance peak, aka less treble.

 

[Kam]

Re: Low input vs. High input

Oh ****, that would explain why I thought my amp got suddenly darker. I thought there was a problem with the tone stack but it's just because I've been forced to use the low input since the high died on me. It never occured to me that it might be just one unconnected problem rather than two things ****ing up at once.

Awesome. Hopefully it'll cost less to get it fixed then. :friday:

 

[Lazarus1140]

Re: Low input vs. High input

I've never noticed any change in EQ, just in volume. I'll typically use the high input channel for single coil guitars and the low for humbuckers; seems to balance them out a bit and gives a little more clean headroom with the higher output buckers.

This.

 

[That90'sGuy]

Re: Low input vs. High input

I don't know the technical reasons behind the difference in sound, but I've always heard people refer to the high input channel as the "treble" channel, so I've assumed that there is something in the gain structure that, in addition to adding gain, also adds some treble to the circuit. Whether that is true or not I have no idea.

It's been scientifically proven that the way we hear things at higher volumes verses lower volumes is very different. As you turn down volume, it always appears as if the signal rolls off the high end. I've seen some amp designers add treble pots to compensate for the built in attenuation controls for that very reason.

 

[Lake Placid Blues]

Re: Low input vs. High input

What amp are we talking about? The Hi/lo inputs on different amps may be totally different in what they do. For example, the Hi input on a plexi simply has a dirrent set of resistors, so it pads the input signal less. But on a JCM800 2204 the Lo input actually by-passes the first gain stage. Different things. Some amps have different impedance inputs and so forth. Really depends on the specific amp's circuit design.

 

[uOpt]

Re: Low input vs. High input

BTW, the proper way to test it to try a guitar with EMG pickups. If the EMGs sound the same on both inputs (sans volume) and the passive pickups do not then it is capacitance or impedance load, with the latter being the much more likely candidate.