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Psyche scarring
Also, do you have the inbuilt noisegate disengaged?
I'm Switching To ENGL (Zim Blasphemy Content!)
- Thread starter zimbloth
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- engl fireball 100 zimbloth
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Sepultorture
Murder Machine
grounding issue or microphonic tube possibly
Umm, I know that certain (if not all) Engl amps have protection for it, but dude running a tube amp without having a load (being plugged into a speaker) risks blowing the output transformer. Like I said Engls are supposed to protect against this, but it's not something I would ever care to risk. I'm no amp doctor and can't diagnose amp problems via the internet, but I would certainly be hoping that doing what you listed above isn't the source of your problem.
leonardo7
Banned
I noticed the issue at practice when I had both heads ( ENGL and Mesa) connected via whirlwind ab switch each to their own cab with amps plugged into a furman power conditioner. I was getting the sound only from the ENGL head. I tried everything. Put the the amps in different places, switched speakers always with the stand by off etc. I decided when I was home later to try and plug in speaker cable at low volume with stand by on one time and went "wait, thats the sound" when I connected the speaker cable. It happened at practice before I did this load connection with standby on. I couldnt have damaged it that way cause it happened before I did that. Everything about it sounds great except for the screech.
Im hoping its a microphonic tube but how do I diagnose it and find out which one?
Im hoping its a microphonic tube but how do I diagnose it and find out which one?
leonardo7
Banned
Even with standby off?
You won't hurt the amp by switching ONLY the power on without a load as long as the standby is off. At least I'm am 90% sure of this, so don't take my word for it. I am overly careful, so I'm not powering it on at all without a load...
JJ Rodriguez
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Even with standby on. You should NEVER run an amp without a load. Quickest way to fry your transformers.
Some amps have protection, but that doesn't mean it's a good idea to do it.
Some amps have protection, but that doesn't mean it's a good idea to do it.
leonardo7
Banned
Well just to be safe I wont anymore and I dont think I fried anything. Strange thing is that the sound doesnt happen everytime I play the head. Once it does happen though, it tends to stay that way. I just turned on the amp and theres no screech. This happened last night, after 10 minutes of playing the sound appeared.
JJ Rodriguez
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No spare tubes around eh?
To be honest I wouldn't be surprised if it's the tubes (as mentioned before). While using stock Engl tubes in my invader I encounter something similar from time to time when playing a low B power chord then muting it. Yours sounds like it might be more drastic of an issue then what I'm experiencing though. When I hear it, it sounds to me more like I'm letting a high string ring out (sorta) and while it's happening, no matter how much I deaden the other strings, it persists. BUT it doesn't happen all the time. I'm about 98% certain my issue is a tube issue, but it just doesn't happen much for me so I haven't bothered laying down the money for new tubes.
I can't say with certainty that tubes will solve your issue but in general I haven't been overly impressed with the stock engl tubes, they tend to crackle and pop when warming up and cooling down for me, which is something I never experienced with my past tube amps. They are just generally noisy tubes, but the crackles and pops I experience are just the tubes themselves making noise, not audible sounds through the speakers.
I can't say with certainty that tubes will solve your issue but in general I haven't been overly impressed with the stock engl tubes, they tend to crackle and pop when warming up and cooling down for me, which is something I never experienced with my past tube amps. They are just generally noisy tubes, but the crackles and pops I experience are just the tubes themselves making noise, not audible sounds through the speakers.
leonardo7
Banned
So I can replace it with any tube that has the same rating? How do I find the bad tube? If thats what it is.
Hmm, that is weird, because my tech switched my amp on (only power, not standby) when he swapped the pre-amp tubes. I asked him and he told me it wouldn't hurt it as long as the standby was off.
Is that an ENGL thing? Or was what he did dangerous to my invader?
I'm 99% sure you've got a microphonic preamp tube.
About the age old standby thing. It IS 100% safe to power on an amp in standby, not connected to a load. People do it all the time and run their effects send to a recorder with cab modeling. A comparison, people run stereo power amps, my self included, with one side of the amp in standby (connected to nothing) as a common practice. Doesn't hurt a thing. ONLY the heater circuit is active when standby is on. The power transformer is not active at all.
About the age old standby thing. It IS 100% safe to power on an amp in standby, not connected to a load. People do it all the time and run their effects send to a recorder with cab modeling. A comparison, people run stereo power amps, my self included, with one side of the amp in standby (connected to nothing) as a common practice. Doesn't hurt a thing. ONLY the heater circuit is active when standby is on. The power transformer is not active at all.
leonardo7
Banned
I was kinda thinking that. In the box from ENGL came two extra ENGL ECC83 preamp tubes. Do most amp companies ship out a few extra tubes with an amp just in case? Now how do I find the one that needs replacing again?
Well the cheapest place to start would be to buy one 12ax7 and just try it in place of each 12ax7 until it either rectifies the problem or you figure out that it's not a preamp tube issue. If the problem is intermittent then wait till a time when it seems to be having the issue and then try the tube swapping as you'll accomplish nothing doing the test while the problem isn't occurring.
As far as tube selection goes, to my knowledge a 12ax7 is a 12ax7, but I really like how you can look at the reviews of different brands of tubes at "the tube store"
12AX7 Tube Type Review
I've never actually ordered anything from them though. Another option is if you bought it from a store then you can take it to them and perhaps they'll help you solve the problem.
If if ends up being a power tube problem (which I doubt it is) you run into the issue of needing to use matched pairs as well as needing to re-bias the amp. It's doubtful the power tubes are the issue, but if for some reason you need to replace them you might as well just buy all new power tubes and have the amp rebiased at the same time. There's no point in replacing half the power tubes in an amp, in my opinion, since you'll have to pay a tech to re-bias the amp each time you change them.
Edit: Since the amp came with the spare preamp tubes you can use my advice above just minus the needing to buy anything. If they sent 2 like they do with the invader, I believe one is labeled something like "first class" or something similar. That is the one that goes in the V1 position. The other tube goes in any other position. Check your manual for help with this.
Thanks for clearing that up, repped!
With the amp on, running through a cab, tap each preamp tube with a pencil or something. It will be very obvious which one is microphonic
Thanks for all the responses in the last couple days, I've been super busy and didn't see Leo's question. I agree its most likely a pre-amp tube issue
Congrats dude
I honestly can't believe it after all the Engl hate you spread about here but... HELL YEA! Good tone is good tone, brand names = nothing. leonardo7
Banned
Basically It turns out the V5 input stage preamp tube was microphonic so I switched it out with the tube that came with the amp labeled "use as input tube only" whereas the other spare tube that came with the amp says "for use at any position". Long story short and after a quick 5 minute changeout and my first time changing a tube, I can say that my amp is running great and sounds brutal. Im glad I asked in this thread. I didnt want to start a new one. Thanks guys! And as far as the thread, I cant blame you Zimbloth for making the switch. ENGL rules! 
Sepultorture
Murder Machine
Basically It turns out the V5 input stage preamp tube was microphonic so I switched it out with the tube that came with the amp labeled "use as input tube only" whereas the other spare tube that came with the amp says "for use at any position". Long story short and after a quick 5 minute changeout and my first time changing a tube, I can say that my amp is running great and sounds brutal. Im glad I asked in this thread. I didnt want to start a new one. Thanks guys! And as far as the thread, I cant blame you Zimbloth for making the switch. ENGL rules!
i knew it, mwahahahahaha
