JVM owners.....suggestions???

[jdr94]

i just started getting this wierd lowend electric fart sound. sorry thats the best way i could think to explain it. its mainly on the od channels when i do some heavy palm muting. bad preamp tube? also i havnt retubed this since i got it, but then i'm kinda low on funds atm so i'm kinda hopin someone has crossed this exact problem and can save me some time n money to keep it up and running for another month til i can completly retube it

[Chief_CrazyTalk]

I couldn't tell you, as I'm not familiar with those...but perhaps you could borrow a known good preamp tube from someone and test your preamp tubes one by one to see if the good one fixes the problem?

Tubes can be hit or miss but usually should last a while. Preamp tubes are cheap, if you have to buy one, and seem to last a long time.

Is there a warranty?

[chrisolson]

Mine was making a burping sound - very quiet but noticeable, and then the power tubes started going. One thing you might want to try if you can - see if you can run a different impedance (safely), and see if it goes away. That;s what I did, and it helped until they just gave up the ghost.

[lhrocker]

Sound like it could be a tube issue. If you don't have spares at the moment, maybe you can move them around to see if the problem follows? Also, check out the JVM forum as they have tons of people who can help, even the guy who developed the JVM.

[jdr94]

thanks guys. yeah Pete, i gotta do more searching on the jvmforums. i'm pretty sure its tubes, well, hope its only tubes. i swear i have bad luck or my amp's are always trying to tell me to stop playing ha ha

[DonP]

Everyone is saying tubes, but with old amps (or newer amps with cheap components), farting out is caused by filter caps that are failing. The filter caps are what keep the low end tight. People like older Marshall 100's from the 70s and early 80s because they had 5 filter caps instead of 4. People at first didn't notice by looking inside the amp, but they noticed the tone had changed. This happened at a similar time as the vertical vs. horizontal input change.

You might say no way could these be failing already, but I've seen many, many computer motherboards and power supplies fails because of cheap caps that exploded (ozzing out stuff) or just swollen up.

I had a brand new power supply do it. It was too late to take back (past 30 days) so I bought a bunch of caps and fixed it myself.

Save that, check your speakers.

[Spivonious]

+1 on the filter caps. Take it to a tech. I waited with my Genz Benz and it ended up taking out more components when it finally went dead.

[jdr94]

ok, i'll be callin the tech this weekend. i can find the money somehow. i'll let you guys know what the problem was once its fixed.

[DonP]

First try swapping tubes if you have a good set to try.

[jdr94]

unfortunatly i dont have a any good ones sittin around. also i only have 6l6's as far as power tubes sittin around. i did swap around a few pre's with one i know is good, but it was still the same. maybe a lil less farty, but only ever so slightly

[mrhiwatt]

Are you sure it wasn't a speaker flubbing out? What are you resonance and bass settings? I can make my speakers flub if the bass and resonance is to high. MrHiwat

[jdr94]

i'm pretty sure it isnt the speaker. i pulled and reset each power tube in sequence and now the sound is gone. are power tubes supposed to be totally silent? i can tap one with a finger nail and hear a *ding* ring thru the speaker. microphonic or normal? it doesnt make any crazy noise other than the ding.

[fordsho90]

I was having similar issues w/my Line 6 hd100 about six mo. after I got it. I know the sound your taking about and at first I thought something else was wrong with it not thinking that a tube/tubes would give out after only six mo. of use. Well I pulled all the tubes and checked and reset them all and while I was pulling them it looked like one had started coming out of its socket. Well just like you the sounds went away and it sounded just fine, well a few weeks later it started coming back again only worse and then once the tubes got hot and I started to really push them it started to cut out and when I looked in the back of the head (while still playing) the tube was looking like a roman candle. I ended up ordering all new tubes and retubed it myself and the problem went away; hope this helps....

[Spivonious]

i'm pretty sure it isnt the speaker. i pulled and reset each power tube in sequence and now the sound is gone. are power tubes supposed to be totally silent? i can tap one with a finger nail and hear a *ding* ring thru the speaker. microphonic or normal? it doesnt make any crazy noise other than the ding.

If they're microphonic you'd hear a loud, long ringing. If you just hear the thud of your fingernail, that's fine. It's possible that the tube contacts aren't making good contact and reseating them made a better connection.

[jdr94]

ok. took me awhile to get it to a tech, but he said all was fine. i havnt heard the sound come back. is it really possible that its like what ^^^ said? seems fine. sounds fine. no sqealing. not even using a noise suppressor anymore.:dunno: