Dual Rectifier 2010 - Serial Loop not 100% Wet ?

[UnderJollyRoger]

Hi folks,

I just discovered, while playing around with a Line 6 M13 that the loop is apparently not 100% serial ...

I realized while playing with a heavy stuttering Tremolo that there's a faint amount of the original signal still audible ... furthermore, when I plug cables in the send and return but don't connect them to any effect and just leave them on the ground, the same happens: the original signal (especially noticeable with more gain) is still slightly audible ... seems the audio signal has a second path besides the serial loop ...

I can live with that, but I wonder if anyone else has noticed this or is my amp probably a lemon ? It's working absolutely fine beside this ...

Thanx in advance.

 

[domct203]

That is normal, and has been discussed many times.

The loop is indeed 100% series. What you are hearing is the interaction between the two triodes in the FX Loop Driver tube (a 12AX7 is really two tubes in one glass envelope).

Dom

 

[elvis]

+1. Usually only an issue at low volume. At high volume the feedthrough is usually masked.

 

[UnderJollyRoger]

Thanks for the clarification. Apparently I didn't catch the last discussion about this ...

Well, like I said, it's probably not a big deal. If I really need an on/off tremolo or a complete volume swell, I can always put it before the amp (to be true, I like my effects more in the loop, but, no problem).

 

[domct203]

Wow, if you can't do a volume swell then I guess the bleed must be pretty bad for you? I have a G-Major in the Loop of my Roadster (OEM serial loop) and I tune on stage with the G-Major muted (via expression pedal) and the bleed is well below the noise floor on stage (I can't hear it, even in the monitors).

Maybe try swapping your FX Loop driver tube? If you don't have any extras try swapping V4 with V5 to see if the bleed level changes at all.

Also, what are your channel masters and FX Loop Send level? Real hot signals into the loop will just make it worse.

Dom

 

[UnderJollyRoger]

My channel master is about 10:00 for channel 3 modern (output is at 12:00) and the fx-loop is at 12:00.

I think it might be the best to record a short clip to demonstrate ... I will do that in a few days. I have a few spare tubes that I can swap for experimenting in the meantime.

I really can't tell how bad the bleed is. It's only really noticeable when I expect no signal at all (like the heavy tremolo), but then it's clearly there. I mostly tune through the tuner out, not the loop, so that's no problem.

 

[joeydego]

I too hear bleed when tuning the the loop with the tc electronic g system. I have audible phase but only at low volumes. Non issue at stage volume.

 

[NOWAYBACK]

Hi,

I have a TC Electronics G Sharp in my loop, the tone changes considerably when the loop in my DR multiwatt is engaged at low to moderate output volume. The effect is like a loss in low end with a nasal character to it and midrange emphasis that is not pretty at all, to the point that is almost unacceptable, even with all effects bypassed (but the unit still in the signal path). When the output is increased, the effect becomes masked, eventually dissapearing at typical concert levels. Phasing issues are the cause, this is a serious design glitch for an amp in this category. By the way, the Mark V suffers the same low volume, poor loop performance.

Best,
Marcelo

 

[elvis]

You may also have an impedance mismatch. Like most TC gear, the input impedance of the G Sharp is 13k. You can probably get the low end back with a decent line-level buffer.

 

[NOWAYBACK]

You may also have an impedance mismatch. Like most TC gear, the input impedance of the G Sharp is 13k. You can probably get the low end back with a decent line-level buffer.

Thanks for your suggestion; I though it was an impedance issue initially, so added both sides of a stereo rack EQ unit by DBX (20 KOhm imput, 50 Ohm output) as an input and output buffer with exactly the same sonic results. The ideal input impedance would be more on the 100KOhm range, but still I should have percieved some improvement which I didn´t. Besides, I believe an impedance mismatch would more likely traduce in less dynamic headroom instead of a dramatic change in the midrange character, introducing the same effect regardless of the output volume. I see your point in relating bass with headroom, and the mids emphasis percieved could be the result of less bass.

Best,
Marcelo