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Post by gtrjunior on Jul 5, 2016 19:32:51 GMT -5
Ok I have 2 question...one of which I should know the answer to but I don't: 1) stomp box pedals in the fx loop...what do I want to set it to +4 or-10? I should know this but I don't. I have it on +4 right now only because it seems to sound better but it's only a slight difference.
AND....#2 question. This one has me a bit worried
A couple of weeks ago I was playing and the amp made a crackling noise followed by a slight drop in volume. So I shut the amp down and waited a few minutes and turned it back on. Whatever the problem was seemed to be gone. A few days later it did the same thing, this time I noticed that one of the pedals I had in the loop ( and sitting on top of the amp) had wiggled a patch cable slightly loose....problem solved, or so I thought. Just now I'm playing the amp and it does the volume drop thing again (without the crackling this time), kind of fluctuating up and down. So of course I checked the patch cable again and my guitar cable. All is good. All of my tubes are glowing in what seems to be a correct glow. The speaker cable is inserted properly. I also noticed that when it was "warbling" in volume some of the "sparkle" was missing and when it (the volume) evened out the sparkle was present again...
I emailed Scott 2 weeks ago when it first happened, before I found the loose patch cable. He seemed to thing it could be a tube, either power or preamp.... Have any of you had an issue like this at all? Any ideas as to what it could be? If you believe it to be a tube, how would I narrow it down to power or pre?
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Post by briman on Jul 5, 2016 21:44:47 GMT -5
Yeah I had the exact same symptoms happen to me years ago with my Competition. Crackling and popping sounds and then a drop in volume. It would return to normal after. Couple nights later, I was playing and heard a loud pop and looked into my amp and to my horror, one of the power tubes was crazy orange red burning color like it was on fire!! I immediately shut off the amp and took the power tubes back to store because I bought them only a few days before, put the new ones in and re-biased. Everything was ok. It turns out, i had a faulty tube. They were brand new Ruby's and the guy at the store said it happens once in a while.
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Post by briman on Jul 5, 2016 21:48:31 GMT -5
I think you definitely have a power tube problem lurking!
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Post by splawndude on Jul 5, 2016 23:31:16 GMT -5
1.) Not a hard and fast rule but for amps with a series effects loop (like a Splawn) it is usually best to run rack gear at 4+ dbu and pedals at -10 dbu. YMMV.
2.) Def sounds like a tube problem. The first thing I would do is pull each tube one by one and spray the tube pins with contact cleaner. Don't spray into the sockets. Work the tube in and out a bit to 'clean' the sockets. Then make sure they are seated down all the way. If you get crackling or a volume drop again then consider replacing some tubes. Remember that tube testing vid I posted awhile back? Try that too.
Good luck mang!
Edit: I recommend Dioxit contact cleaner.
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Post by gtrjunior on Jul 6, 2016 4:25:01 GMT -5
Thanks guys....ill pick up some Deoxit and clean the contacts and see what happens. I'll clean both power and preamp tubes. I'll re watch that vid too...
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Post by gtrjunior on Jul 6, 2016 4:45:22 GMT -5
I'm assuming that the QR gets biased no differently than any other amp, right? I bring my amps to a tech for biasing....Is there anything he needs to know that would be different from biasing my JCM 800?
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Post by splawndude on Jul 6, 2016 9:51:40 GMT -5
Naw - same basic procedure.
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Post by TheFight on Jul 6, 2016 10:34:45 GMT -5
Definitely a tube problem. I had the same problem with my first quickrod, piping followed by volume drop.
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Post by gtrjunior on Jul 6, 2016 11:11:02 GMT -5
Naw - same basic procedure. Thank you sir!
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Post by gtrjunior on Jul 6, 2016 11:11:54 GMT -5
Definitely a tube problem. I had the same problem with my first quickrod, piping followed by volume drop. I'm guessing the stock Chinese el34's are probably just junk....
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Post by gtrjunior on Jul 6, 2016 11:13:33 GMT -5
1.) Not a hard and fast rule but for amps with a series effects loop (like a Splawn) it is usually best to run rack gear at 4+ dbu and pedals at -10 dbu. YMMV. 2.) Def sounds like a tube problem. The first thing I would do is pull each tube one by one and spray the tube pins with contact cleaner. Don't spray into the sockets. Work the tube in and out a bit to 'clean' the sockets. Then make sure they are seated down all the way. If you get crackling or a volume drop again then consider replacing some tubes. Remember that tube testing vid I posted awhile back? Try that too. Good luck mang! Edit: I recommend Dioxit contact cleaner. I did the tap test on the preamp tubes...seem normal. Obviously the gain stages have a slight audible noise but no "ringing". PI was silent. I have some of this....good enough?? www.google.com/shopping/product/676335587616357776?lsf=seller:8740,store:9066114129753103117&prds=oid:5713365836495142536&q=wd-40+contact+cleaner&hl=en-us&ei=Uy59V6GfDoj5-AHHmbTQDg&mid=syrjdvt4k%7Cdm_mtid_8903tb925190_pcrid_50645156379_pkw__pmt__product_206356189_slid_&lsft=gclid:CO__2ead380CFRNZhgodTsYMig
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Post by splawndude on Jul 6, 2016 11:40:42 GMT -5
Yeah - that should be fine.
When I first saw WD-40 I screamed NOOOOOOOOoooooo!
But then I saw the 'specialist' and 'fine electrical equipment' and 'leaves no residue' part so it should be OK. Just don't ever use regular WD40 because it will leave behind an oily residue that will then actually attract more dirt.
On the tap test make sure you are listening for the tapping coming through the speakers. That is the key. You may have to separate the cab from the amp a fair bit. I bought a 20ft speaker cable just for that reason - but I only use it for doing that. Otherwise, I use the shortest cable possible.
I personally do not trust chinese tubes so I wouldn't doubt that is the problem but honestly - it could be any number of things. Power tubes do not go microphonic very often but they do exhibit other problems. Volume drop being a big one.
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Post by briman on Jul 6, 2016 18:20:54 GMT -5
Yeah mine were Ruby's which i was told are re-labled chinese tubes!
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Post by gtrjunior on Jul 6, 2016 22:16:16 GMT -5
I had Rubys in my JVM... They sounded and worked fine. I never had a problem with them per se... This is the first time I've ever used these tubes which I am guessing are Shuguang...last time I use them too...lol
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Post by gtrjunior on Jul 6, 2016 22:18:41 GMT -5
Yeah - that should be fine. When I first saw WD-40 I screamed NOOOOOOOOoooooo! But then I saw the 'specialist' and 'fine electrical equipment' and 'leaves no residue' part so it should be OK. Just don't ever use regular WD40 because it will leave behind an oily residue that will then actually attract more dirt. On the tap test make sure you are listening for the tapping coming through the speakers. That is the key. You may have to separate the cab from the amp a fair bit. I bought a 20ft speaker cable just for that reason - but I only use it for doing that. Otherwise, I use the shortest cable possible. I personally do not trust chinese tubes so I wouldn't doubt that is the problem but honestly - it could be any number of things. Honestly, power tubes do not go microphonic very often but they do exhibit other problems. Volume drop being a big one. I had originally bought this wd-40 to clean guitar vol pots and pedals etc. I was gonna buy some Deoxit after work tonite but I remembered I had the WD...
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