#1
ok so my friend has this krankenstein dime edition head, thats had a bunch of problems. my other friend and i played the same head at GC like 3 weeks before he bought it and no problems, sounded great. he took it to this kinda funky amp tech, which we think messed it up, and of course our friend who bought the head isnt as knowledgeable about amps so he doesnt know what hes paying for. it just seems kind of fishy.

so let me break it down.
he got the head and said there were some noise issues and some other stuff. he took it the fishy amp tech who said there were a bunch of blown capacitors and things and put new tubes in it and rebiased and everything. one thing that tipped us off is that our friend who owns the amp said that the tech mentioned that the krank was "picky" about what tubes you put in. wtf? another thing, is that the guy charged him 80$ for the whole job. a new set of tubes for this amp without bench/labor fee should be more than that. (what, did this guy put garbage tubes in it or something?) either way, our friend got it back and then called us about it saying it sounded weird and lost its low end. a krank. with no low end? oxymoron is you ask me. he said he tweaked it alot and got it to sound better, but it was way different from before it went to the tech.

on top of this, he ordered new speakers from eminence, four 16 ohm speakers. he had our other friend wire them up, whos basically never had any experience with this stuff, and of course did it wrong. all he did was wire it up and put the speakers in, didnt check it with a multimeter or anything. so our krank owner friend calls us up and wants us to take a look at the cab. we took a multimeter over and it turns out the way the guy blindly wired the speakers was a whopping 64 ohms mono 32 ohms stereo. WTF. so my friend and i got that problem sorted out now hes at the proper 16 ohm mono 8 ohm stereo.

after we fixed the cab, we tested his head through it and one of the first things ive noticed was everything looked normal, until i flip the standby switch to on, and all the power tubes turn blue. ive never seen that before, but from my research it seems thats not necessarily bad. my friend probably has the gain way up, he plays like tech death ish stuff i guess, and from what ive read the blue glow just means the tubes are REALLY being driven. also, the gain channel sounded immensely fizzy. these symptoms lead me to believe that the tubes are bad, and im thinking it had alot to do with our resistance problem i mentioned before.

now i get a text a little bit ago from him saying that one of the pre amp tubes is glowing brighter than the rest and he cant even tell if the others are glowing or not, and right now im waiting on his reply, i told him to turn the lights off and make sure if they are glowing, and while hes at it to turn the gain and volume down to see if his power tubes still glow blue. thats where we currently stand


so theres the description, now the questions.
is this blue glow bad? too much gain? too high of a bias? bad tubes?
could the resistance have done this or had a hand in it?
fizz/grain also a sign of bad tubes?
what about the pre amp tubes, if they are all in fact glowing, is it normal for one to glow alot brighter than the others?

ive done some tube work in my day but ive never really seen anything like this stuff thats happening with my friends amp. he keeps taking it to all these damn techs and people who dont know what theyre doing or just trying to get more money out of him before consulting my friend and i who are pretty much the most well versed in this stuff around here and he doesnt listen to us anyway until someone else tells him the same thing we did then hes like "oh.. woops" so now hes in this situation. id like to just tell him to give me the amp for a day or two to look through it and whatnot but he doesnt seem to like the idea i guess. maybe if i steer him right with this like his cab yesterday id could be of more help but for now this is all ive got and you guys are my support ha so what do you guys think? sorry for the wall of text btw.
Gibson SG Special Faded(Super Distortion/PAF Pro)
Carvin V3M
Jet City JCA2112RC
Taylor 114e
Ibanez SR300e

Quote by Delanoir
In 60 years, there will still be Opeth.
You know why?
Death ain't got **** on Mikael.
#3
Quote by darkwolf291
Can we get a tl;dr up in this bitch?


I miss DGM

haha sorry it was so long but it needs explaining. there is kind of a tl;dr its the second paragraph from the bottom.

an whats DGM?
Gibson SG Special Faded(Super Distortion/PAF Pro)
Carvin V3M
Jet City JCA2112RC
Taylor 114e
Ibanez SR300e

Quote by Delanoir
In 60 years, there will still be Opeth.
You know why?
Death ain't got **** on Mikael.
#4
Okay,

- Blue glow is NOT bad. It's simply an indication of more plate current in the tubes than you are used to seeing.

- The impedance mismatch that severe, depending on how long the amp was played, likely resulted in some transformer damage which I strongly suggest you have an amp tech confirm or rule out. A damaged output transformer can absolutely cause tonal issues, or worse.

Also, the tubes might have been fine when they were installed, but they could also have suffered due to the mismatch.

I would take it back to the tech and explain what happened. The tech sounds more on his game than you might believe. But if you distrust him, find another and have them evaluate the amp.
Tastes like chicken, if chicken was a candy.
#5
Quote by ConfederateAxe
Okay,

- Blue glow is NOT bad. It's simply an indication of more plate current in the tubes than you are used to seeing.

- The impedance mismatch that severe, depending on how long the amp was played, likely resulted in some transformer damage which I strongly suggest you have an amp tech confirm or rule out. A damaged output transformer can absolutely cause tonal issues, or worse.

Also, the tubes might have been fine when they were installed, but they could also have suffered due to the mismatch.

I would take it back to the tech and explain what happened. The tech sounds more on his game than you might believe. But if you distrust him, find another and have them evaluate the amp.

ok, i didnt like the blue glow, but from what ive read and your confirmation, its ok.

but the impedance, he said the amp was played a couple of times a week for a couple of hours of band practice for two weeks. is there any way for us to diagnose the transformer ourselves? i figured the mismatch would either screw up the tubes or transformer, i hope its just the tubes.

most of the amp techs in the area(there are seriously like two) arent that trustworthy. my friends and i have had bad experiences with them. which is why id like to diagnose ourselves if we can but if we need to well take it to a tech again
Gibson SG Special Faded(Super Distortion/PAF Pro)
Carvin V3M
Jet City JCA2112RC
Taylor 114e
Ibanez SR300e

Quote by Delanoir
In 60 years, there will still be Opeth.
You know why?
Death ain't got **** on Mikael.
#7
Quote by Linqua5150
ok, i didnt like the blue glow, but from what ive read and your confirmation, its ok.

but the impedance, he said the amp was played a couple of times a week for a couple of hours of band practice for two weeks. is there any way for us to diagnose the transformer ourselves? i figured the mismatch would either screw up the tubes or transformer, i hope its just the tubes.

most of the amp techs in the area(there are seriously like two) arent that trustworthy. my friends and i have had bad experiences with them. which is why id like to diagnose ourselves if we can but if we need to well take it to a tech again



There are simple DMM tests that can be done to determine damaged windings or a dead transformer, but unless you can determine which leads are connected to your B+ side (this requires circuit knowledge), it'll do you no good.

Transformers can be very tough, but like I said, the severe impedance mismatching that the amp was enduring, repeatedly as you said, is enough to burn up a winding. Contrary to popular DIY belief, too much impedance kills transformers more often than too little due to inductive kickbacks or "spikes" that harm windings.

You may have to take it out of town to get it reliably evaluated. Good luck.
Tastes like chicken, if chicken was a candy.
#8
i dont know what the B+ side would mean but ill do some research. if all else fails itll probably be a tech. thanks
Gibson SG Special Faded(Super Distortion/PAF Pro)
Carvin V3M
Jet City JCA2112RC
Taylor 114e
Ibanez SR300e

Quote by Delanoir
In 60 years, there will still be Opeth.
You know why?
Death ain't got **** on Mikael.