|
|
Post by briman on Dec 30, 2019 9:13:50 GMT -5
On Saturday I was playing at home and all of a sudden....my jcm800 started making swirly crackling noises like popcorn popping with windy swirly noise. I shut her down immediately. Plugged guitar in only and still there on both inputs. Noise volume increases and decreases when turning volume knob on amp.
So i bought brand new power tubes, installed and biased. Still there! 😡 I tapped on all pre amp tubes and no issues. The only thing i haven't tried yet is putting in new pre amp tubes. Gonna try that tonight.
If pre amp tube replacement doesn't solve it, i will take to my tech. My guess is a bad cap or resistor somewhere.
Anyone else ever have the same symptoms?
|
|
|
|
Post by splawndude on Dec 30, 2019 12:03:25 GMT -5
Hey Briman.
My first guess would be a bad or microphonic preamp tube. If you have time, take one known good preamp tube and cycle it through all the slots and take notes of what tube is where and what changes, if any, you detect. If you have good gloves you can do this while the amp is turned on to save time. If you have a loop mod, you could try plugging guitar directly into FX return. You can also hit your jacks with some contact cleaner (spray on cable, not socket) and work that cleaner in. I assume your guitar sounds fine in another amp? Power tubes would have been my last thought. If all if this leaves you with the same problem then a poor solder joint might hopefully be the last easy (easier) fix before swapping components. If you practice safe electricity habits you can tap on those solder joints with a chop stick or similar while amp is on and listen. At that point though, I'd probably be taking it to a tech anyway.
Good luck.
|
|
|
|
Post by briman on Dec 30, 2019 14:55:47 GMT -5
Hi Splawndude! Hope you are enjoying the Holidays! Yeah i am going to put in all new pre amp tubes tonight when i get home. I am hoping that will fix it. I haven't moved the amp an inch for over a year now so i don't understand how a solder joint can weaken but i guess it's a possibility...
Fingers crossed that the pre amp tube change fix it.
Thanks for your help!
|
|
|
|
Post by splawndude on Dec 30, 2019 16:23:47 GMT -5
Hope you are having good holiday times as well.
If it were to be a bad solder joint then it could fail at any time - doesn't have to have movement involved.
My advice is to avoid the common desire to put all new preamp tubes, test, walk away.
That won't help you narrow down the problem and could make trouble shooting more difficult. I would roll one good one through first and see what happens.
Good luck brother.
|
|
|
|
Post by briman on Dec 31, 2019 7:09:01 GMT -5
Yay!!! I put in my spare pre amp tubes and it solved the problem! It was the 1st one that was screwed. Amp sounds awesome with these new jj's! More bottom and articulation than the tung sols that were in there before.
|
|
|
|
Post by splawndude on Dec 31, 2019 11:42:49 GMT -5
Glad that solved it.
Yeah - I dig the JJs too.
I think in your amp (most Marshalls) V2 is a cathode following stage and Tung Sols are not recommended there. Not sure if you've ever heard that before. Not saying that has anything to do with your issue either. So did you toss the bad one that was in V1 and keep the rest as spares?
|
|
|
|
Post by briman on Dec 31, 2019 14:23:19 GMT -5
Yeah i tossed it and keeping 2 others as backups.
|
|
|
|
Post by cvogue on Jan 2, 2020 12:56:50 GMT -5
Late to the game but yeah that smacks of a dodgy preamp tube for sure, glad you got it sorted out. Interesting... I tried JJ's way back when in a Peavey Classic head and they sucked, a muddy mess. Tried them in my Blackstar years later and they were great! Put a couple in my Street Rod and I like them a lot. Depends on the amp. B)
|
|
|
|
Post by briman on Jan 2, 2020 14:44:24 GMT -5
Yeah i have always used tung sol and electro harmonix mostly for power amps tubes. This is the first time trying jj's and to be honest......i don't think i have ever been as impressed with my tone!
One of my buddies hates jj's but i really think it depends on what amp they are in. They do get alot of love on the net from jcm800 owners.
|
|
|
|
Post by cvogue on Jan 3, 2020 12:49:40 GMT -5
Yeah i have always used tung sol and electro harmonix mostly for power amps tubes. This is the first time trying jj's and to be honest......i don't think i have ever been as impressed with my tone! One of my buddies hates jj's but i really think it depends on what amp they are in. They do get alot of love on the net from jcm800 owners. Yeah I hear a lot of raving about Tung Sol preamp tubes... tried them and swapped them out. Just too "in your face" for me. Although what kind of amp you have them in probably plays into it. See my above post about JJ's!! |
|
|
|
Post by gtrjunior on Jan 20, 2020 10:42:28 GMT -5
This is exactly what my JCM 800 does when it needs power tubes...
|
|
