hi,Teemuk and everyone ...i have some questions:
i've just repaired my amp (the repairman said it was because of a loose solder-so he re-soldered it)..but now, i think my amp tone has changed..i'm just wondering :
1. can that kind of repairing - re-soldering a loose solder - change the tone of my amp? (or is it only because of my poor hearing n feeling about my amp tone?(cause i rarely use that amp  )
2. and i also, would like to know,what kind of repairing stuffs that can altered the tone of my amp?
thx u

hello, i'm new here and really glad to find this forum... i really need help for my amp here..i have a solid state amp Hughes& Kettner blue edition 30 r , i already had it for 3 years now and i really like this amp, an amazing practise amp <3)...but a few days ago, this amp having trouble ..the volume is decreasing suddenly in both channel: clean and lead channel and it always synchronized...(if my clean channel volume is decreasing, the lead channel is also decreasing,..visa versa..) it sounds like that there is a sound that want to goes out but it can't ... this problem came in no precise time and paroxysm...sometimes in the middle of my playing and sometimes it already came just as i start turning on the amp volume...

i have tried to isolate the problem by using my amp's "return" to know if the damage is on the preamp or power amp, but i think the power amp is still ok..(the "master" volume is still in perfect condition and no volume decreasing there)....
i also use another guitar and cable or even using another amp to find if the problem is on my guitar or cable but i found that my guitar and the cable are just fine...i also always keep my amp away from the wall to keep a proper ventilation for my amp..

and then, yesterday, i found that i can have the volume back to normal if i turn the volume knob to the maximum position or strum really hard to the strings of my guitar...so as an example: if i have my volume decreasing in some position(x position), then i can fix it if i turn the volume knob to maximum position and the amp volume is back to normal...(if i turn the knob to x position again, the volume produced by my amp is normal for the x position again) ......but then i found also that it won't stay long, the problem will come again and again...

what's wrong with my amp? i have never use my amp too loud or too harsh..i even rarely use this amp, it spends more time in the box then out in my room ( it because of my busy schedules i have for the last 2 years)

btw, is the problem is on the preamp?  is this a problem that i can handle by myself? cause i'm thinking that it is because of a dirty pot or dirty input..is it possible? i'm thinking this because few a days ago, i didn't put my amp to the box and i also put this amp uncovered in my room and i let my cable stay plugged in the input socket..can it be the cause of this problem? if it is, how can i clean the input socket and the pot? could you give me the steps on how to do it? and is there any cautions or danger for my amp that i need to know for doing this?

another question : a few days ago, i also use this amp for playing my acoustic electric nylon guitar ...could it also be the cause?

sorry, i am asking a lot of question and emotional words, i am a newbie on a world of amp and i really love this amp....this amp is so important for me...
please help....thx u