#1
Hi guys, I am new so forgive me if i sound a little uneducated as i play guitar, i cant fix them.

I have a Mesa Boogie Dual Rectifier Head and a Marshall Mode 4 Quad, yesterday it started to make a crackling noise on channel 2. Could it just be a tube that needs replacing? I ask, cause all tubes are lighting up. Which seems strange?

Thank you.
#2
Pre tubes may still be the problem.
Or the cable.

How old are the tubes?
May the amp have taken some hits recently?
Have you tried going from the guitar to the amp with a different cable?
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#3
Quote by Spambot_2
Pre tubes may still be the problem.
Or the cable.

How old are the tubes?
May the amp have taken some hits recently?
Have you tried going from the guitar to the amp with a different cable?


Thank you for reply,

Yes, have tried different cable and different guitar,
Amp has not taken any bumps or hits,

I have not changed the tubes since i brought it April 12th 2012.
#4
This might help you.

http://vid545.photobucket.com/albums/hh384/buckethead_311/Amp%20stuff/Microphonicpreamptube.mp4

Try swapping some tubes around and see what happens. Also, maybe get some Dioxit contact cleaner to clean the tube pins before you put them back in.
#5
It sounds like a failing preamp tube.

To trouble shoot the preamp tubes, take a new/known good 12AX7 and swap it into each preamp position, one position at a time. Test the amp in-between each swap to pin-point the tube that is potentially causing the issue.

Thanks!
#6
if replacing the tube doesnt help, take some contact cleaner which you can find at any radioshack or electronics store and spray it into all the tube sockets. I suspect its just dirty tube sockets.
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#7
Quote by bustapr
if replacing the tube doesnt help, take some contact cleaner which you can find at any radioshack or electronics store and spray it into all the tube sockets. I suspect its just dirty tube sockets.


I would NOT spray it into the sockets!!! Instead, use an old 12AX7 and spray it on the pins, inserting and removing the tube in each socket a few times. Thanks!
#8
Or use contact cleaner on pipe cleaners to clean the individual pin holes.

The only thing not already mentioned is resistors. Yes, a weak tube or dirty tube sockets can cause what you're describing, if it sounds like bacon frying it can also be resistors going bad. After a few years of getting hot and cooling down they can develop fine hairline cracks in the resistors, especially the larger carbon comp ones. i had to replace several in my Fender Super Reverb, sounded like bacon frying all the time when idling.

If that's the case, take it to a good tech, don't try it yourself. The voltage inside a tube amp is literally deadly. If you touch the wrong thing, it's not good...if it doesn't kill you on the spot, you're going to the hospital when you hit the other wall of the room...

Yes I'm serious. Tube amps carry 400V DC and sometimes more, and a lot of high voltage is stored in the large capacitors, called filter capacitors, for several months after being powered down. Very dangerous in there, just like a TV. Don't touch it if you don't KNOW what you're doing.

Oh yeah, spraying contact cleaner into the sockets won't hurt them. But the best way is to use pipe cleaners. In some cases they also need to be retensioned, which means opening it up, see the warning above.
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#9
Quote by MESA/Boogie
I would NOT spray it into the sockets!!! Instead, use an old 12AX7 and spray it on the pins, inserting and removing the tube in each socket a few times. Thanks!

+311

Don't ever spray that stuff in a tube socket no matter what company makes the amp
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#10
Quote by Paleo Pete
Or use contact cleaner on pipe cleaners to clean the individual pin holes.

The only thing not already mentioned is resistors. Yes, a weak tube or dirty tube sockets can cause what you're describing, if it sounds like bacon frying it can also be resistors going bad. After a few years of getting hot and cooling down they can develop fine hairline cracks in the resistors, especially the larger carbon comp ones. i had to replace several in my Fender Super Reverb, sounded like bacon frying all the time when idling.

If that's the case, take it to a good tech, don't try it yourself. The voltage inside a tube amp is literally deadly. If you touch the wrong thing, it's not good...if it doesn't kill you on the spot, you're going to the hospital when you hit the other wall of the room...

Yes I'm serious. Tube amps carry 400V DC and sometimes more, and a lot of high voltage is stored in the large capacitors, called filter capacitors, for several months after being powered down. Very dangerous in there, just like a TV. Don't touch it if you don't KNOW what you're doing.

Oh yeah, spraying contact cleaner into the sockets won't hurt them. But the best way is to use pipe cleaners. In some cases they also need to be retensioned, which means opening it up, see the warning above.


Absolutely. Once preamp tubes have been ruled out, cracking can be caused by a resistor, typically a plate resistor. Thanks!
#11
Thank yous all very much, some great feedback, I will go buy a new set of tubes and try testing, Great help.

Thanks again.
#12
You may not NEED a SET of tubes. Preamp tubes don't wear with use the way power tubes do...so the best way to troubleshoot is by taking ONE new tube and swapping into each position, one position at a time. Test the amp in between each swap - if there is no difference, put the tube that was there back and move to the next position. When you DO hear a difference, you have pin-pointed the tube that needs to be changed. Thanks!
#13
It is nice to have an amp maker chime in on issues that arise. obviously Mesa takes pride in there work, like all USA company's should
#14
Thanks! We take as much pride in our customer service as we do in our amplifiers!!
#15
Quote by MESA/Boogie
Thanks! We take as much pride in our customer service as we do in our amplifiers!!

well it is showing. I have found that companies that are genuinely concerned about consumers are few and far between these days, but it is good to see from a company like yours

PS please make a 50 watt Mark V
Last edited by Robbgnarly at Oct 29, 2014,
#17
Not quite loud enough for me. I know many are like 15 watts will be good for gigging, but I need at least 50watts. my 20 watt 1980 barely works for band practice, and that is lower than the level we play live
#18
Mesa - I didn't know it could be narrowed down to the plate resistors, I don't know all that much, but with my Super Reverb it was all of the very old carbon comp 1/2 and 1 watt resistors causing it to sound like frying bacon. Since the thing was made in 1973, I had to replace every capacitor in it, and quite a few of the resistors, now I have a slight frying bacon sound back, and definitely in the reverb section, but I haven't opened it up and tinkered with it yet. I suspect a weak tube this time...Still hsave one other minor issue, vibrato section but it sounds fantastic now. I don't use the vibrato so I haven't worried about it but I'm looking up info for that too, might go ahead and try to fix it before long.

Anubis - Mesa is right, you might not need a full set of preamp tubes, just one or two and swap out one at a time to find the weak one. Preamp tubes don't need to be biased, so you won't have that to worry about. I say one or two because it's always a good idea to have at least one spare around.

Robb - I once played through a friend's 22 watt Caliber series Mesa, mid 80's amp, that thing would keep up with any 50 watt amp I've ever played. Don't know what the modern Mesas will do, but if they are anything like those, the 22 would keep up with any 50 watt going, the 50 watt Caliber series would match any 100 watt amp on the market. If you can't get enough out of a 50 watt amp. maybe you need more efficient speakers.
Last edited by Paleo Pete at Oct 29, 2014,
#19
Quote by Robbgnarly
It is nice to have an amp maker chime in on issues that arise. obviously Mesa takes pride in there work, like all USA company's should

Why "USA companies"? Did you really need that qualifier?
#20
Quote by Cathbard
Why "USA companies"? Did you really need that qualifier?

It's just nice to know that they are out there and taking an interest in what is going on with their products

Had a 22 caliber and it was great for alone practice, but would never get over a drummer for me
Last edited by Robbgnarly at Oct 29, 2014,