Roadster Combo question - Hum and effect loop question

[antiwheel]

I bought a 2008 Mesa/Boogie Roadster 2x12 combo. The condition was great and I loved it.
ust 2-3 days ago, a strange problem showed up.
The amp will have a static noise, it's not really the hum. and it is louder when I use channel 3 and 4 or Channel 2 in Brit mode. I tried to diagnoze it myself.
1.This noise is still there when I just plug the guitar cable in (no guitar). So it’s not from my guitar pickup.
2, I then tried different good cables and the noise is still there. So it’s not because of bad cable.
3, However if I touch the end metal part of guitar cable. The noise is weaker. Almost 50% gone. So I though it might be a grounding problem.
4, Try good power feed. Noise is still there.
5, Because it happens mostly in Channel3 and channel 4. I thought about bad tubes. Then based on the instruction in Manual, I changed the two END 12Ax7 and all 6L6s. The noise did not go away. Same.
6, Then I was confused and play around the back pannel by switching nobs and switches.
Suddenly, I found that if I turn the volumn nob of “LOOP” down, the noise decreased. But I did not have the FX LOOP in and the LOOP switch is set up as “Loop System Active”. And if I switch the FX LOOP to “Hard Bypass”, the noise is back the same volumn as before.
7, I also found changing the FX LOOP volumn will change the whole amp output. Say if I turn FX LOOP to minimum, the amp output need to be over 12 O’ clock compare to 9 o’clock when I set FX LOOP volumn to middle, considering same Master volumns.

So is it normal that FX LOOP volumn affects the amp output even there is no FX loop there?
And why FX LOOP volumn will change the amp output?
If you guys have already talked about this, please share me the thread link.

 

[ibanez4life SZ!]

The output change from the effects loop is normal.

That knob controls the signal strength of the preamp to your effects loop. So, if you turn it down, it tames the signal...if you turn it up, it pushes it hotter.

As for the static noise, my Roadster actually does the same. I called Mesa, and they couldn't really help...told me to take it to a tech. It really doesn't bother me enough to pull the amp out of my road case, and undo all the wiring, and not have it for 2 months while it's with Mesa, so I haven't sent it in.

Let me know if you find anything.

Eric

 

[antiwheel]

Thanks!
I think I found the reason of this hum/static noise. It's the power source!
The roadster is currently in my basement studio. I took it to the first floor of my house and connect to the power there and the noise is 80% gone.
I will buy some good extension cord and maybe a power conditioner so I can record stuff in my basement.

 

[antiwheel]

It did not work. The noise is still there especially for channel 3 and channel 4. For channel 1 and 2, when I move the amp upstairs, it's quiet. Channel 3 and channel 4, no matter what it's noisy.
Also the noise is huge if I turn the Loop to "Hard bypass". It unbearable.
Could it be a preamp tube problem? will a power regulator help?
I am running out of ideas. can someone help me on this?

 

[b0nkersx]

If changing the outlet helped significantly, then the problem might be with the wiring in your house.