Fender Champion 30 question

[ThomasJ2352]

Firstly...thanks for the forum...greatly appreciated....have an operating question about the Champion 30....for a number of years I have used a Roland Micro Cube and for bedroom practice it seems fine....meaning for me its quite when I want it quite....ie...no hum....well I was given a Champion 30 some time back and have blown the dust off it and, for very clean warm jazz kinda stuff it seems to sound quite nice....except for a slight but noticeable (at least in a very quite bedroom) hum (not quite as loud as Marty McFly standing pic in hand in front of Doc's 6' speaker)....knobs have no impact and the amp does sound very nice otherwise.  My question is.....is this normal for this vintage/era amp? Are hum-less amps the exception and not the rule? Maybe time to throw a blanket over the unit as a hum notch filter?
Thanks again for the forum....would appreciate any comments.
Tom

[J M Fahey]

Does it still hum if plugged into other outlets around the house?
Or does hum change if you move it around?
It *might* be a poorly filtered supply *or* picked from some nearby appliance *or* poor grounding at your home.
It's a straight from the wall powered amp, while I guess the Roland Micro Cube is powered either from batteries (which are floating and humless) or some *external* regulated power pack, which both provides extra filtration and places hum inducing transformer at least a couple feet away.

[joecool85]

I worked on a Champion 30 for a customer a year ago.  I noticed it had a fair bit of hum while just sitting "idling".  I believe it is just poor design (audio grounding as well as not enough power supply filtering), but I never dug into it because the customer just wanted a cheap fix (broken input jack).

[ThomasJ2352]

Thanks for the input....
  It hums no matter where in the house I plug it in...and the comment about battery powered cube (and/or remote transformer/dc supply) I think
explains a lot....
  I'm not sure what i can do about the audio grounding but I can add more ps filtering....think I'll give that a go....shouldn't be too difficult (famous last words!)
Thanks again

[phatt]

I'd be wary about messing with it. (winky warning)

without an intricate understanding of electronic circuitry and the pletora of pit falls in design and layout you maybe walking into something you will regret.

Consider that a lot of Amps hum (big name brands as well).
So if they have not solved the issue in years of R&D,,, what are your chances of success?

Also,
What might seem like a problem in a bedroom is drowned out in a live venue. Hum and buzz is always an issue at low levels while using hi gain circuits.

If you think your Champion 30 has a bad design flaw then go find a Fender Pro Junior,, the green PCB model has the worst hum of any fender Amp I've experienced.
Except for a Laney LC 30 where the hum on OD channel was louder than the guitar signal,, and that was from Factory.
(took me quite a while to solve those problems) :grr

Joe Cool's observation is enough to tell me that it's unlikely to be worth fixing.

But if you just can't bear the issue,, then post pictures of front and back of the PCB and with the mountain of collective knowledge here there is a chance it can be *improved*,,,, notice I did not say FIXED. 8|
Phil.
 

[ThomasJ2352]

Thanks for the input...just what I was hoping to hear....regarding years of R&D....it has been sometime since
I biased a transistor amp (an old 2N2222 I think it was back in the day). I did a few minor tests...
  1)  tripled the capacitance on the +/- of the ps.....no difference
  2)  disconnected the final amp stage and the hum quieted slightly...not enough to get excited about...
  3)  reconnected it and disconnected a previous stage...still not much difference
  4)  concluded that its inherent in the design (easy way out I suppose)
  5)  took all the knobs off and cleaned the entire unit...doesn't look too bad at this point

Think I'll use it for areas with higher noise floors (not the bedroom!)
Thanks again for the input...greatly appreciated...

[joecool85]

...Think I'll use it for areas with higher noise floors (not the bedroom!)
Thanks again for the input...greatly appreciated...

I think this is the best idea.  I will say that for such a basic old amp, the one I had worked on really did sound pretty good.  It was loud for a 30 watter too.

[bobhill]

I have a pair of the dsp versions of the Champion 30, one from 03 and the other 04, and I have found them do be very dependent on the room they are in as far as their noise output. Their power line filtering is not very strong, any room with dimmers on the lights will cause them to complain, not much better with florescents. The dirt channel amplifies whatever noise is in the environment, so I guess it's a good thing all I use are the clean channels. That is the main negative I've found about these amps.

On the other side, at home in my computer room where I use them to test pedals and other "quiet" playing, these things are great. I have plugged everything I have into them, run them in stereo, experimented with cheaper guitar and pickup combinations, and found them very pleasing to these old ears. And very noise free in a room with computers, tv, wireless router, you name it. Quiet with cs69's in my strat, with the 492/498's in the LP studio, the whatever they spec'd for the PRS SE hollowbody, the Ibanez acoustic piezo's, just quiet amps with all my guitars. Although I do not recommend plugging a bass into them. The 10" can get a bit flubby when you get serious on the bass. The other occasion when the stock speaker can get a bit flubby is with some external modulation pedals. Extreme settings on the pedals will cause the bass response to complain. Not enough speaker to move the required amount of air. External distortion/od they like just fine.  They can get bright, but the onboard eq can and does keep the icepick under control.

I have played with mine for several years now, they are great for their capabilities, loud enough with 30 watts (actually spec'd for 27.5, but marketing...) for some jamming/gigging, and one hell of a lot easier for these 66 year old bones to haul around then the full stack superlead I was hauling in the 70's. Or the pair of blackface Bandmasters I currently try not to move very often.

I like them, but as always, your needs, ears etc. etc. YMMV LSMFT I can be held to no opinions expressed or implied. Very decent good sounding lightweight small combo's that can be found very cheaply.