silverfoxnik Posted September 9, 2007 Share Posted September 9, 2007 Hi Folks Looks like I'm posting a weekly gear problem thread, which is not a good sign for me...Anyway, this weekend's instalment of bad news at Silverfox Towers is that I have just bought a Gallien Kreuger 700RB head, which sounds great, is easy to use, compact and gives out a lovely tone.. But in a scenario typical of buying untested s/h gear (why have I not learnt this lesson yet ), it has problem which is that it makes this hissy sound which I can only describe as 'snap, crackle and pop' . Though the three different sounds do not always occur at the same time. It happens more when playing through it but not exclusively as it also happens if the amp is on and there's no lead in the input socket.. I've checked my speaker cable, mains cable, instrument cable. Also, ran another amp on same mains circuit as a comparison, but other amp is clean of this unwanted noise??? So, before I go back to the seller and ask for a refund or whatever, I thought I'd ask here to see if anyone has a clue as to what could be causing this noise and how easy/difficult, cheap/expensive it might be to fix.. Because I love the tone of the amp it'd be good to keep if it can simply be fixed. Thanks as ever! Cheers Nik Quote Link to comment Share on other sites More sharing options...
dirtystatic Posted September 9, 2007 Share Posted September 9, 2007 (edited) Dont know if this is any help but I used to have an old 300w peavey mixer head which I ran into a custom 15" cab (my first rig). I was getting the same sort of sounds.. a constant hiss that would then crack violently and end with a loud pop. After that it would return to normal and then the hiss would start building up again. If I increased the volume on the amp the noises didn't get any louder, they stayed at a constant level So I took it apart, i cleaned the pots and then the jack sockets an repaired what looked like a few dry joints and put it back together, there was a slight improvement but not much. My dad had a listen and because of the natures of the sound he suggested it might be the capacitors. He chopped the old ones out and took them to maplin to look for some matching ones... soldered them in and hey presto, good as new... I dont know if theres away of testing the capacitors with a multimeter maybe.. but it's definitely worth some concideration seeing as your problem sounds alot like mine! Hope this helps Edited September 9, 2007 by dirtystatic Quote Link to comment Share on other sites More sharing options...
bass_ferret Posted September 9, 2007 Share Posted September 9, 2007 You are not having much luck are you. Quote Link to comment Share on other sites More sharing options...
NickThomas Posted September 9, 2007 Share Posted September 9, 2007 I used to have this problem with a trace elliot combo ..... I used to regularly use what's commonly known as percussive maintenance ... failing that I'd probably stick your amp in for a service with an amp tech ... probably cost you about £60 Quote Link to comment Share on other sites More sharing options...
silverfoxnik Posted September 9, 2007 Author Share Posted September 9, 2007 [quote name='bass_ferret' post='57683' date='Sep 9 2007, 11:42 AM']You are not having much luck are you.[/quote] Correct analysis of the situation John! Combination of foolishness and being impetuous plus huge blind spot in the common sense department.. Nick - your solution is probably the best route to take i think, should I keep the amp! Cheers Nik Quote Link to comment Share on other sites More sharing options...
BOD2 Posted September 9, 2007 Share Posted September 9, 2007 I agree with what dirtystatic said above .... Assuming you've removed all trace of "Rice Crispies" from the amplifier... In order of ease of operation the possible solutions are 1. Clean the pots and jack sockets using a contact cleaner fluid (e.g. Superservisol) 2. Check the circuit board for dry solder joints 3. Check/replace capacitors The second option requires you to be handy with a soldering iron. Solder joints should be shiny and silver, not dull and grey. With a little care you can resolder "dry" joints fairly quickly. Option three is much more serious, especially as it requires you to source new capacitors of exactly the same ratings. This is not something to undertake lightly - it's time consuming and there's no guarantee it will fix the problem. Quote Link to comment Share on other sites More sharing options...
silverfoxnik Posted September 9, 2007 Author Share Posted September 9, 2007 [quote name='BOD2' post='57745' date='Sep 9 2007, 02:54 PM']I agree with what dirtystatic said above .... Assuming you've removed all trace of "Rice Crispies" from the amplifier... In order of ease of operation the possible solutions are 1. Clean the pots and jack sockets using a contact cleaner fluid (e.g. Superservisol) 2. Check the circuit board for dry solder joints 3. Check/replace capacitors The second option requires you to be handy with a soldering iron. Solder joints should be shiny and silver, not dull and grey. With a little care you can resolder "dry" joints fairly quickly. Option three is much more serious, especially as it requires you to source new capacitors of exactly the same ratings. This is not something to undertake lightly - it's time consuming and there's no guarantee it will fix the problem.[/quote] Thanks BOD2 and dirtystatic..the consensus is pretty telling in itself. What I'm going to do first is go back to the seller and see what happens next. I know there's one or two good amp repair wizards locally so I might go and see them as well. Appreciate all the help folks - while you're at it, got any suggestions as to how to get my head repaired too! Cheers Nik Quote Link to comment Share on other sites More sharing options...
Bass_Junkie Posted September 9, 2007 Share Posted September 9, 2007 well its usually caused by the application of milk to rice krispies, it will then 'snap, carckle and pop' for a short while. try using a spoon and things should clear up in about 5-10 mins. sorry, someone had to say it. Quote Link to comment Share on other sites More sharing options...
Subthumper Posted September 9, 2007 Share Posted September 9, 2007 If you should change the PSU caps be sure that they're properly discharged first or you may be in for a surprise.I've know big electrolytic caps hold big charges for weeks.Though generally I'd never trust any cap. Cheers Just Quote Link to comment Share on other sites More sharing options...
silverfoxnik Posted September 9, 2007 Author Share Posted September 9, 2007 [quote name='Bass_Junkie' post='57922' date='Sep 9 2007, 09:25 PM']well its usually caused by the application of milk to rice krispies, it will then 'snap, carckle and pop' for a short while. try using a spoon and things should clear up in about 5-10 mins. sorry, someone had to say it.[/quote] LOL Thanks for stepping in with that one as it needed to be said... And thanks for the safety advice Subthumper - I've heard that said before so will be appropriately cautious should it come to that, Nik Quote Link to comment Share on other sites More sharing options...
Gazm Posted September 10, 2007 Share Posted September 10, 2007 [quote name='BOD2' post='57745' date='Sep 9 2007, 01:54 PM']Option three is much more serious, especially as it requires you to source new capacitors of exactly the same ratings. This is not something to undertake lightly[/quote] The ratings need not be exactly the same. Similar ratings (+/- 10% maybe more in my opinion) would suffice. Different replacement types will even work without a major change of tone (ie. polycarbonate/polyester instead of ceramic). However, make sure the voltage rating of the replacement is at least as high as the existing cap especially for electrolyic/tantalum bead and ensure polarity sensitive components are correctly polarised. Pete. PS. I would change the capacitors first not last, especially if the amp is aging a bit. PPS. [quote]It's time consuming and there's no guarantee it will fix the problem[/quote]+1 on that but won't hurt to do so! Quote Link to comment Share on other sites More sharing options...
silverfoxnik Posted September 10, 2007 Author Share Posted September 10, 2007 [quote name='Gazm' post='57988' date='Sep 10 2007, 01:09 AM']The ratings need not be exactly the same. Similar ratings (+/- 10% maybe more in my opinion) would suffice. Different replacement types will even work without a major change of tone (ie. polycarbonate/polyester instead of ceramic). However, make sure the voltage rating of the replacement is at least as high as the existing cap especially for electrolyic/tantalum bead and ensure polarity sensitive components are correctly polarised. Pete. PS. I would change the capacitors first not last, especially if the amp is aging a bit. PPS. +1 on that but won't hurt to do so![/quote] Cheers Gazm! Am getting a local tech person to do it...It would never work again if I tried to do it.... Nik Quote Link to comment Share on other sites More sharing options...
johnm Posted September 10, 2007 Share Posted September 10, 2007 [quote name='silverfoxnik' post='58178' date='Sep 10 2007, 01:14 PM']Cheers Gazm! Am getting a local tech person to do it...It would never work again if I tried to do it.... Nik[/quote] send it to Beyer Dynamic, they are the importer for GK. They'll give you a quote on the repair cost................... Quote Link to comment Share on other sites More sharing options...
fusionbassist1 Posted September 10, 2007 Share Posted September 10, 2007 for future reference and for anyone reading the thread with similar problems i'll chuck this thread in here aswell about excess humming etc from amps and likely causes. very well writen and detailed. [url="http://basschat.co.uk/index.php?showtopic=194"]http://basschat.co.uk/index.php?showtopic=194[/url] I had the same problem from an all valve amp and didn't want to venture forth so i ended up shopping it back instead hah Quote Link to comment Share on other sites More sharing options...
silverfoxnik Posted September 10, 2007 Author Share Posted September 10, 2007 [quote name='fusionbassist1' post='58399' date='Sep 10 2007, 07:34 PM']for future reference and for anyone reading the thread with similar problems i'll chuck this thread in here aswell about excess humming etc from amps and likely causes. very well writen and detailed. [url="http://basschat.co.uk/index.php?showtopic=194"]http://basschat.co.uk/index.php?showtopic=194[/url] I had the same problem from an all valve amp and didn't want to venture forth so i ended up shopping it back instead hah[/quote] Thanks for that link - lots of common sense stuff there and some good technical info too, especially the article by Rane. Johnm - will have a check to see what Beyer would charge though I suspect it'll be expensive as compared to a local option. Latest update on this whole issue is that the person I bought it from has offered to have the amp repaired which is good news. I'm just negotiating now as to how and where to get it done... Will let you know the outcome as and when. Thanks again for the help! Nik Quote Link to comment Share on other sites More sharing options...
Bass_Junkie Posted September 10, 2007 Share Posted September 10, 2007 [quote name='silverfoxnik' post='57978' date='Sep 10 2007, 12:39 AM']LOL Thanks for stepping in with that one as it needed to be said... Nik[/quote] always happy to help. Quote Link to comment Share on other sites More sharing options...
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