Effects Loop and channel master levels interaction

[davidp158]

I'm getting early distortion in my LSC's channel 1 that I'd like to resolve. I'm trying to get a full, clear tone that won't break up at all (or very, very little) unless the solo switch is engaged. My LSC is an original version, 1x12 combo with an EV 12 speaker. I typically run both channels @ 100 watts, and use 6L6 power tubes.

I have to keep the channel 1 input gain below 9:30 to avoid harsh clipping, especially with humbucker pickups. The channel 2 midrange control adds significant distortion if set over 12:00. My channel 2 input and drive settings are usually around 11:30 -12:00. With these settings, my channel 1 master is often at 2:00 while my channel 2 master is around 9:00 to 9:30. Per settings I've seen the owner's manual, and settings posted here, my clean channel 1 master level seems to be out of wack with my channel 2.

BTW, I use a TC Electronic Nova System in the effects loop, and have spent a lot of time trying different settings for the effects loop send knob (typically between 12:00 and 2:00) and the Nova System's input setting and output setting. If I bypass the effects loop, the distortion in channel 1 isn't significantly improved. Also, the ratio between the channel 1 and channel 2 master volume settings don't change. Although I do prefer the tone of the effects loop bypassed, I prefer to use the loop for effects and like the solo foot switch option. I use high quality cables and occasionally clean all jacks with Deoxite to make sure I have solid connections.

Also, I did the "Reeder Mod" on this amp, and it clearly made a big improvement on the channel 2. I doubt this has an impact on channel 1, but thought I'd mention that I've done it.

Any suggestions? Different V1 or V3 tube?

Description of Tube Functions (per the owner manual):

V1 A = CH2 Drive Stage
V1 B = Input Gain Stage

V2 A = 3rd Gain Stage
V2 B = 2nd Gain Stage

V3 A = FX Loop Send
V3 B = FX Loop Return

V4 A = Reverb Return
V4 B = Reverb Drive

V5 A = Phase inv/driver
V5 B = Phase inv/driver

 

[Maury]

Maybe its one of the tubes or the EV speaker? I like to run my LSC cleans to have no breakup too. Just gigantic high headroom cleans. I run my CH1 gain around 2:00. treb 1:00 mids 12, bass 12, pres 12 and channel master 11:00. Output around 10-11 for most gigs. I have 2 single coils and a bridge humbucker and they're an "average" distance from the strings. I get a full, loud clean tone with no breakup. My tubes are stock mesa. I also run a nova repeater in the loop and I have it hooked up using its high-headroom input. Works great.
HTH.

 

[davidp158]

Maury,

Thanks for your post. I know its not the speaker, as the same kind of distortion occurs with the stock speaker.

I am hoping its just a tube, but not sure which ones to test and what would be good replacement options.

My humbucker pickups are medium gain, so I don't think its an issue with humbuckers overdriving the preamp.

I will try my channel 1 with your settings and see if its any clearer.

thanks!

Maybe its one of the tubes or the EV speaker? I like to run my LSC cleans to have no breakup too. Just gigantic high headroom cleans. I run my CH1 gain around 2:00. treb 1:00 mids 12, bass 12, pres 12 and channel master 11:00. Output around 10-11 for most gigs. I have 2 single coils and a bridge humbucker and they're an "average" distance from the strings. I get a full, loud clean tone with no breakup. My tubes are stock mesa. I also run a nova repeater in the loop and I have it hooked up using its high-headroom input. Works great.
HTH.

 

[Maury]

you have way more patience than me I would have already swapped out one preamp tube at a time.

 

[djw]

Subjectively speaking, the OD on Ch1 shouldn't be very harsh, actually. It should be pretty smooth and tweedy, so maybe your V1 is crunchy. Definitely try some new preamp tubes. But first I'd try backing off on the Master volumes a little and work with your global Output control. The Masters seem to add a bit of gain relative to the output stage. This might be heightened by whatever is happening with the preamp tubes, so the effect might be subtle. Or not.

I do find it hard to keep my signal absolutely clean with humbuckers, though I don't actually like a completely clean "clean", if you know what I mean ...so I probably don't have super-applicable advice in this department. In any case, single coils appear to be much easier to manage for sure; the LS' input is pretty sensitive and easy to boost into a furry drive, so you might really need to go with some extreme settings to get the clean and drive you want with humbuckers.

This has already crossed your mind I'm sure, but if you're willing to change up your guitar's setup you could try lowering your pickups a bit too.

 

[davidp158]

DJW - Thanks for the comments and taking time to reply. I will try your suggestions in the next day or two.

I wasn't aware that the individual channel masters contribute to the effects send level, until re-reading the manual. As I have to set my clean channel 1 master so much higher than the channel 2 master (for unity gain when switching between channels), I'm thinking this may be part of the problem. When I see the level settings that others are using, I typically find their channel master levels are much closer together.

I agree that humbuckers can be hard to keep 100% clean, and I think the midrange character has a lot to do with this. I normally don't mind a little hair on my clean signal, but the distortion I'm getting is just way more than I'd like.

cheers,
Dave

Subjectively speaking, the OD on Ch1 shouldn't be very harsh, actually. It should be pretty smooth and tweedy, so maybe your V1 is crunchy. Definitely try some new preamp tubes. But first I'd try backing off on the Master volumes a little and work with your global Output control. The Masters seem to add a bit of gain relative to the output stage. This might be heightened by whatever is happening with the preamp tubes, so the effect might be subtle. Or not.

I do find it hard to keep my signal absolutely clean with humbuckers, though I don't actually like a completely clean "clean", if you know what I mean ...so I probably don't have super-applicable advice in this department. In any case, single coils appear to be much easier to manage for sure; the LS' input is pretty sensitive and easy to boost into a furry drive, so you might really need to go with some extreme settings to get the clean and drive you want with humbuckers.

This has already crossed your mind I'm sure, but if you're willing to change up your guitar's setup you could try lowering your pickups a bit too.