Bleed on low volumes and when using effects in loop.

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Bigshredder

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Hi guys :) this is my first post here. I have a dual rec 3 channel multi watt head that is almost 2 years old. And I have always used it with the loop bypassed because the tone is more open and clear. But today I fiddled around with a g-major in the loop and there was a lot of ugly fizzy bleed Noise. It is i serial loop right? Even when I unplugged the g-major and set the loop to bypass and turned the volume all the way down I could clearly hear the fizzy bleed tone. What's up with that? Is my amp broken? Or is this normal? The loop is useless if I can't get 100% wet sound using effects. I am using a Torpedo live unit as a load box and with impulses so I can hear all the little bleeds and stuff through my headphones. Any thoughts on this matter?
Cheers.
 
Each 12AX7 is actually two separate circuits. What you hear at very low volumes is signal being produced in one half of the tube bleeding over into the other half of the tube. It's not an issue at normal operating volumes because the normal signal is much more powerful than the bleed signal, it only really becomes an issue at very low volumes where the bleed signal overpowers the normal signal.

Long story short, Dual Rectifiers weren't designed to operate at very low volumes.
 
But that doesn't explain the leakage when trying to do a wet delay or ambient sound with effects in the loop. There shouldn't be any dry sound in the path. That has got to be a flaw.
 
Is I use the loop I set it to taste. Usually at noon. But If I bypass the loop I set my master all the way down. Then it is bypassed and I only use the channel volume. But the bleed happens when I turn down att the volume or use the loop with effects.
 
No I havn't. I bypass the loop and the bleed/leak is there when I turn down the volume to silent.
 
Bigshredder said:
I bypass the loop and the bleed/leak is there when I turn down the volume to silent.

That's normal. It's bleed across the triodes in the preamp tubes.

The amp wasn't designed to run silently, it was designed to drive a cabinet at normal (for guitar) volumes.
 
screamingdaisy said:
Bigshredder said:
I bypass the loop and the bleed/leak is there when I turn down the volume to silent.

That's normal. It's bleed across the triodes in the preamp tubes.

The amp wasn't designed to run silently, it was designed to drive a cabinet at normal (for guitar) volumes.

Modern modes in Roadster Ch3/4 has this bzzzzzzz sound when playing at home compliant levels. A bit too loud for home and the buzz is gone ;)...

If somebody wants silent operation from 100W tube head and cab with speaker sensitivity ~100db/W the tooling is wrong for the situation. :p Even mini recto is too much an amp for home use with normal speaker cab...
 
Seriously guys!!! I am not running it silently!!! I am addressing an issue of a bleed noise that is there when using the loop and the same when turning the volume all the way down. All the way down means no noise att all!? Right? And to be unable to set the loop to 100 wet but still getting dry signal through must be a flaw in the design right? There must be something wrong when the amp is making buzzing bleed noises when setting the loop to 100 serial/wet. So you are saying that all amps with serial loops have a fair amount of dry bleed in the signal?
 
Bigshredder said:
There must be something wrong when the amp is making buzzing bleed noises when setting the loop to 100 serial/wet.

What effects are you running in your loop?

Are you running the Two Notes in the loop or are you using it off the speaker output?
 
The torpedo live works as a loadbox so the amp is connected to the speaker out. I tried a gmajor in the loop. Set it so serial so it would be 100% so I could try som ambient tones and som modulation/delay tones but the dry bleed (same buzz bleed as when turning the volume all the way down) is very present and it makes it impossible to use the serial loop function on the g-major due to an ugly fizzy sound.
 
As you have the torpedo live you could record clip with the buzz sound so it would be easier to hear what is it you mean? And how are all levels (ins/outs/mix) set in your signal chain (also in g-major)?

I do not have the torpedo so that's unfamiliar thingmabomb to me (I had Palmer loadbox... which somebody has recommended but I did not enjoy...)
 
If I turn down all the vol on the dual rec and switch channels and imoulses on the live unit the sound changes so it definitely goes through the live and through the speaker out. But when I lower the torpedo live volume all the way down the sound disappears so it isn't the live unit that is making the noise from its load. And when I have the G-major connected the dry sound is constant even when I fiddle with the wet sound with delays and mods. So its leaking dry sound through the speaker out from the dual rec to the load/speaker from the preamp.
 
Bigshredder said:
The torpedo live works as a loadbox so the amp is connected to the speaker out. I tried a gmajor in the loop. Set it so serial so it would be 100% so I could try som ambient tones and som modulation/delay tones

"Serial" on the G-Major is a routing option for the effects and has nothing to do with your whether your amp's loop is series or parallel.

The setting in a G-Major for parallel loops is Kill-Dry. You want Kill-Dry on if you're using a parallel loop and Kill-Dry off if you're using a serial loop. In your case, you want Kill-Dry off.

Serial runs Pitch-Chorus-Delay-Reverb in series;

Screen%20Shot%202017-06-25%20at%202.44.42%20PM.png


Parallel runs Pitch, Chorus, Delay and Reverb in parallel.

Screen%20Shot%202017-06-25%20at%202.40.48%20PM.png



but the dry bleed (same buzz bleed as when turning the volume all the way down) is very present and it makes it impossible to use the serial loop function on the g-major due to an ugly fizzy sound.

Is your effects loop send (on the back) set to "Normal" (12:00 position)?

How high are your channel masters set?
 
As far as bleed goes:

On Channel 2, the bleed goes away by turning the presence all the way up. It works the same on Channel 3, except mine gets quieter, but doesn't completely mute.

The presence is connected mechanically to the PI, with relays making or breaking the connection. Whether it's proximity or just the sheer amount of voltage, it leaks a bit from there. Well, it's the only path from before all the volume controls to the power amp that makes sense to me and accounts for an interaction with the presence in both modes on both of those channels.
 
As far as I've learned, screamingdaisy is correct. It is not a "fault" with your amp itself, but a problem with using one tube for the FX loop and another function.

I called Mesa once and complained about it. Told them it must still be a parallel loop. Whoever I talked to insisted it was a serial design, but didn't comment further or inform me about the tube bleed. I found out about that later on my own.

Most all amps I've seen use the same design, but don't exhibit quite the same bleed due to differences in gain structure and how the circuit itself works. I remember reading something about an amp that was made with a dedicated 12ax7 for the FX loop circuit (a Soldano perhaps?) and in theory I'm guessing that would solve the problem. Or at least prevent the issue in the first place.

Anyway, I use a G Major 2 with a Dual Rec Multiwatt myself. By running the head at normal to hotter levels, I can get the overall sound pretty far louder than the bleed and thus don't notice it as much. I also use a Rivera Rockcrusher (which is the bees knees, BTW) and it allows me to keep the volume reasonable while cranking the head.

Sorry I couldn't be much more help than that. Other than to tell you I don't think there is anything "wrong" with your amp.
 
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