My Classic is gettin' noisy

[Dante]

Is there a noise mod for the Classic? Lately, my Classic has an obnoxious hum behind the distortion and brown voicings.

[Harley Hexxe]

Uh oh, sounds like a cap going south. :facepalm:

[Dante]

Well, I put my MP-2 into my rack and opened up the Classic. Admittedly, I don't know what the hell I'm looking at, but I don't see anything swollen or leaking...it all looks pretty dang clean and new. Tubes look pretty old, like they're Sovteks or Chinese from way back (plain red lettering 12AX7, no branding)

Here's a big ass picture of the innards of my Classic, lemme know if you see anything obvious

[Kim]

Probably a long shot, but the easiest shot....

Maybe try another pair of tubes in there since you already have it out and opened?  That's if you have another pair lying about...

[Dante]

I got toobs....lots of them, I love toobies

I'll try that, what the hell

[MarshallJMP]

Ok let us know how that goes.

[Dante]

I swapped out the tubes and initially, I thought it sounded better. Now, it does not. I have a little bit of hum in channel A on high gain, nothing terrible. Channel B is much worse, and it's in the preamp, not the power amp. I tried swapping the cables to be sure, yup, it's channel B of the preamp making the noise.

Grrrrrr.....I may put my MP-2 back in the rack, or rewire my cabinet for mono and only use ChA.

The new tubes are GrooveTubes GT 12ax7R2 and they don't seem as hot as the ones I had in there. I had to turn up the gain on my Brown voicing, but the Distortion sounded fine  :dunno:  It seems like these tubes behave like a lower gain tube, in that I have a bit more room to adjust the finer details of the gain, which is nice.

[Harley Hexxe]

Hey Dante,

    When I initially tried the 12AX7R2's in my Classic, they seemed to be the answer to the perfect match for the Classic. As I bought a few more pairs to try out, I found there was quite a difference in them. It seems GT doesn't match these tubes as tightly as they want you to believe. Of course, now that Fender owns GT, it isn't surprising that the quality has gotten more relaxed.

     Harley 8)

[Dante]

Thanks Harley, I appreciate that insight.

I suspect these are NOS (new old stock) and probably from the days that you remember...they are very nice sounding tubes, just a bit less gain than I had. The cleans are cleaner, which I LOVE, and the gains are more detailed. The Brown voicing now slowly ramps up to the realm of the Distortion voicing. It's actually quite nice.

I'm pretty upset about the noise though...I took the Classic to practice tonight and found myself hitting the clean patch to quell the noise at the end of songs. The bass player said it was like being back in the 70s when things hummed all the time....grrrrr..... Channel A is not nearly as bad, I may use the Classic with the combo amp, which is mono anyway.

[MarshallJMP]

So out B is a lot more noisy then out A?

[Harley Hexxe]

Dante,

   One way to tell if they are the NOS tubes from back in the day, is that the low mids and bass will be boosted slightly. The cleans will sound richer, and the overdrives will be warmer with more clarity.
   The Mullards will give you a little bit of this, but will also give more crispness to the high end. IMHO, the Classic doesn't need that as the highs are already shimmering. So the hunt goes on for long plate tubes that will suit the Classic to my ears...

            Harley 8)

[Dante]

So out B is a lot more noisy then out A?

Yup, it is

[MarshallJMP]

Try this,set the loop to on,and plug something into the return (a plug or a cable with nothing attached to) and see if that changes anything.This way you disconnect anything before the loop, so we can see if the noise is comming from before the loop or after.

[Dante]

MJMP, how do you fit such a large brain into that ordinary sized head?

Your troubleshooting suggestion made me try something. In order to isolate the problem, as you were trying to do, I simply plugged a cable directly into the rack without the pedal board. NO NOISE!! So, realizing the problem lies in the pedal board, I begin eliminating pedals (and cables) down the chain until.....VOILA! It's the cable from my pedal board to the rack. I just had to resolder the tip wire, and it was fine....but wait, there's still some noise...not as much...I go hunting again

It is my tuner pedal.

Unfortunately, the tuner powers all the other pedals....but I have a tuner in my rack, so I'm covered. I'll use the tuner pedal as a power supply only. Just the same, I take the pedal apart to see if anything is loose inside. Nope, all solder connections look good, all wires are firm. I open the pedal battery compartment and there's a (many years old) battery still connected. I took that out and the rest of the noise is gone!!

It was a combination of a bad cable and an old dead battery in my tuner pedal. All is well with my preamp!!!!

[GuitarBuilder]

Great troubleshooting, Sherlock Dante!