Mesa Boogie Bass 400+ Noise with no instrument plugged in.

[b7xx12]

My boogie has fairly new ALL mesa tubes. The unit makes a "white-noise" type sound when the stand-by switch is on and the unit is ready to play (even with no instrument). EVERY tube has been switched out with a brand new tube and still same problem. If you can imagine, it almost sounds like a fingernail being dragged across the speaker cone. It will sizzle for awhile then maybe "pop" a little, then stop., etc. This even happens with ALL volumes and tones in the minimum positions.

[CDweller]

Originally Posted by b7xx12

My boogie has fairly new ALL mesa tubes. The unit makes a "white-noise" type sound when the stand-by switch is on and the unit is ready to play (even with no instrument). EVERY tube has been switched out with a brand new tube and still same problem. If you can imagine, it almost sounds like a fingernail being dragged across the speaker cone. It will sizzle for awhile then maybe "pop" a little, then stop., etc. This even happens with ALL volumes and tones in the minimum positions.

Mine does the same exact thing. I turn it on on standby, and I get the roaring white noise, the random pops, etc. Mine was purchased brand new in February of '10. It started doing this a couple of months ago. I've never gigged the amp, and if it has ten hours on it I'd be surprised. Interested in finding out what you discover. I'm going to bring mine to an authorized repair shop soon.

[cheezewiz]

You've replaced the preamp tubes too, right?

[b7xx12]

Thanks.

[b7xx12]

Yes, I'm considering contacting boogie and getting some idea of bench fee's etc. Shipping from KY to CA and back will be what kills me.

[Nightlyraider]

Have you cleaned all "return" jacks and made sure the effects level pot in the back isn't on an oxidized connection?

I don't know if this will fix your particular problem, but those inputs and the effects channel in the back are all "always on" and a bad connection somewhere in there might crackle a bit.

[lem8r]

Usually bad resistor can make such noise especially when too hot

[anderbass]

Originally Posted by Nightlyraider

Have you cleaned all "return" jacks and made sure the effects level pot in the back isn't on an oxidized connection?

I don't know if this will fix your particular problem, but those inputs and the effects channel in the back are all "always on" and a bad connection somewhere in there might crackle a bit.

That's good advice ^^^

Just try turning your Effects blend knob back and forth a few times.

And then also try patching a cord across your effects send/return jacks.
(your amp has 2 f/x loops, so try this with both front and back loops)

Then just let us know If the problem was suddenly fixed trying any of these quick easy tests.

[levis76]

Ok, here you guys go. I owned a 400+ that did the exact same thing for months with two different sets of tubes. I figured out the problem was loose sockets. The power tube sockets have pinch sockets for each pin. Unplug the amp from the wall, remove the power tubes, and use a small flathead screwdriver to push them closed a bit. You don't want to crush or damage them, just push them shut a bit so they make good contact when you push the tubes back in. Yes, it's a lot of little pins to pinch, but a cheap price to pay to quiet the beast. When reinstalling the tubes, try to push straight down and don't wiggle too much and you should be good to go.

Also be sure to install the quietest preamp tube you have in the V1 postition, first socket on the right. Any noise from that tube will be amplified through the entire system.

[Calaverasgrande]

My amp is from the early 80's, its actually a 400 not a 400+. I have never had this issue.
I have played hundreds of smoke filled bars, outdoor shows in arid, pollen dense northern CA, beach shows etc. It hasnt gotten funked up in any of the fx loops or needed tube socket fidgeting. I would seriously suspect the first couple of preamp tubes.
You don need Mesa tubes in those amps, and they certainly sound better to me with non mesa preamp tubes. IME most mesa preamp tubes are the same noisy chinese tubes that everyone else is using.

A couple of JJ Tesla or Sovtek tubes shouldnt be more than $10-12 each. Try switching out the two tubes closest to the input jacks. If that makes no difference rotate them to the V3 and V4 position. Make sure that at some point every 12ax7 is taken out of the amp and has a substitute. If the noise persists take it to a tech. You can call Mesa and they will reccomend a local tech.

Also, look at the back of the amp while it is in standby. Check to see if any of the power tubes looks different than the others. If they do it will be obvious what I mean. Either redplating or very blue. Or possible other variations.

[CDweller]

Originally Posted by lem8r

Usually bad resistor can make such noise especially when too hot

It's present when the amp is first turned on, and on standby.

[anderbass]

Originally Posted by levis76

Ok, here you guys go. I owned a 400+ that did the exact same thing for months with two different sets of tubes. I figured out the problem was loose sockets. The power tube sockets have pinch sockets for each pin. Unplug the amp from the wall, remove the power tubes, and use a small flathead screwdriver to push them closed a bit. You don't want to crush or damage them, just push them shut a bit so they make good contact when you push the tubes back in. Yes, it's a lot of little pins to pinch, but a cheap price to pay to quiet the beast. When reinstalling the tubes, try to push straight down and don't wiggle too much and you should be good to go.

Also be sure to install the quietest preamp tube you have in the V1 postition, first socket on the right. Any noise from that tube will be amplified through the entire system.

Good advice, I agree BUT FIRST...

Turn your amp on, strike a note, and then while the note is decaying simply unplug the amps 110v power-cord to (hopefully) full discharge the the Capacitors inside the amp.

Then use a volt-meter to very carefully measure and confirm the Capacitors DONT have any residual voltage remaining at the power tube socket connectors before actually touching anything with tools or your hand !!!

Otherwise... you could be very likely be electrocuted and killed touching those tube pin sockets with a tool while trying to tighten them up.

The caps inside UN-PLUGGED amps can store enough voltage/amperage for several days to kill you DEAD. I chit you not.

For this reason alone, Its a very good Idea to only let qualified amp techs preform any of these types of repairs !!!

You've been warned, procede at your own risk.

[mntngrown]

I vote preamp tube. Because of the random pop. Have you ever turned the volume knob off and still hear your bass through the speakers when you play it?
That happened to me with a micro head, with only 1 12ax7.
Changed it and no more problems/pops. Lot of bad tubes out there so even though you changed em a clinker might be in there. I was playin in my garage last night and had a terrible buzz when i took my fingers off the strings.
Plugged into a new electrical socket a few feet away and it stopped. So many possibilities?

[Caca de Kick]

It doesn't sound like a tube issue to me, with this all-tube amp in standby mode there is no signal going through the tubes. Seems like more of a capacitor or even could just be a solder joint issue.

Yes, as mentioned above BE VERY CAREFUL when opening up the chassis and poking around inside. I always unplug the amp and with leaving the cab plugged in, I flip the power and standby switches up and leave it like that for 15-20 mins before I start working on anything to be sure I bled the residual off.

The only time I think I had any real 'crackly' noise issues with my Bass 400 was a wornout standby switch. I could also see it throwing little sparks as I flipped it back and forth. So I ordered 2 new switches from Mesa and simply replaced both the power and standby since they both had the same mileage on them.

I have gone into all the Mesa tube heads I've owned (D180, two 400s, and a 400+) and have had to resolder broken solder joints. A cracked solder joint at preamp heater wire was common on all mine, and several folks that PM's me. Nothing new there with me, I find solder joint repairs common with all-tube amps including the Ampeg I had, 63 Fender still have, and my guitarists Fender HR Deluxe.

[levis76]

Originally Posted by anderbass

Good advice, I agree BUT FIRST...

Turn your amp on, strike a note, and then while the note is decaying simply unplug the amps 110v power-cord to (hopefully) full discharge the the Capacitors inside the amp.

Then use a volt-meter to very carefully measure and confirm the Capacitors DONT have any residual voltage remaining at the power tube socket connectors before actually touching anything with tools or your hand !!!

Otherwise... you could be very likely be electrocuted and killed touching those tube pin sockets with a tool while trying to tighten them up.

The caps inside UN-PLUGGED amps can store enough voltage/amperage for several days to kill you DEAD. I chit you not.

For this reason alone, Its a very good Idea to only let qualified amp techs preform any of these types of repairs !!!

You've been warned, procede at your own risk.

Right, and 7 people in the US die each year testing a 9V battery on their toungues. Really? I don't think so.



Killed? Highly unlikely. It will scare the piss out of you, but unless your a newborn or 80 years old with a pacemaker, or maybe you have 10 ft of bare copper wire wrapped around your ankle and it's tied to earth ground, the likelyhood that you will even get shocked is very slim. I work around 3phase 480/208 all day long, with capacitors 100x the size of anything you will find in an amplifier and the smallest box we have has over 40 of these capacitors, and I have yet to hear of anyone ever being killed by them. Ever. Shocked maybe, but not killed. My electronics instructor in the service used a cap about the size of a D cell battery taped on the end of a pointing stick to wake up sleepy students. He had a little charging station he made for it, and since we all had nice short haircuts, when your chin hits your chest your neck is wide open, POW, your up. Better than any energy drink or caffiene tabs. Pretty sure none of us died, and that was about an inch away from the spinal cord.

A good point has been made here though, be smart and don't touch anything else on the chassis while you snug the sockets. While others may disagree and say its a cap, it fixed my 400+ lickety split, no sh!t. Oh, and did I mention before that this is something you could try and it won't cost you anything but a little time whereas an unecessary cap job will set you back a week at least and a few hundred dollars. Hmm, what should you try first?

[chadds]

Bad advice. This is where the net is hazardous. Is an expert telling you this or a 15yr old with his pants around his ankles?
To put it another way. Pay a tech. The price you pay for a trained person with the proper tools and grounding apparatus is worth it.
Don't be stupid to save a few bucks.
I repeat.
Bad advice.

[anderbass]

Originally Posted by levis76

Right, and 7 people in the US die each year testing a 9V battery on their toungues. Really? I don't think so.



Killed? Highly unlikely. It will scare the piss out of you, but unless your a newborn or 80 years old with a pacemaker, or maybe you have 10 ft of bare copper wire wrapped around your ankle and it's tied to earth ground, the likelyhood that you will even get shocked is very slim. I work around 3phase 480/208 all day long, with capacitors 100x the size of anything you will find in an amplifier and the smallest box we have has over 40 of these capacitors, and I have yet to hear of anyone ever being killed by them. Ever. Shocked maybe, but not killed. My electronics instructor in the service used a cap about the size of a D cell battery taped on the end of a pointing stick to wake up sleepy students. He had a little charging station he made for it, and since we all had nice short haircuts, when your chin hits your chest your neck is wide open, POW, your up. Better than any energy drink or caffiene tabs. Pretty sure none of us died, and that was about an inch away from the spinal cord.

A good point has been made here though, be smart and don't touch anything else on the chassis while you snug the sockets. While others may disagree and say its a cap, it fixed my 400+ lickety split, no sh!t. Oh, and did I mention before that this is something you could try and it won't cost you anything but a little time whereas an unecessary cap job will set you back a week at least and a few hundred dollars. Hmm, what should you try first?

I highly encourage you to go poking around in a charged amp amp and attempt to prove me wrong. T/B would be better off without you and there's way too many freakin people in the world anyway!

You'd be doing mankind a huge favor, go for it man!

[chadds]

Originally Posted by b7xx12

Yes, I'm considering contacting boogie and getting some idea of bench fee's etc. Shipping from KY to CA and back will be what kills me.

There has to be an authorized repair person near you.

[b7xx12]

Originally Posted by Nightlyraider

Have you cleaned all "return" jacks and made sure the effects level pot in the back isn't on an oxidized connection?

I don't know if this will fix your particular problem, but those inputs and the effects channel in the back are all "always on" and a bad connection somewhere in there might crackle a bit.

Thanks I will try this.

[BassmanPaul]

Originally Posted by levis76

Right, and 7 people in the US die each year testing a 9V battery on their toungues. Really? I don't think so.



Killed? Highly unlikely. It will scare the piss out of you, but unless your a newborn or 80 years old with a pacemaker, or maybe you have 10 ft of bare copper wire wrapped around your ankle and it's tied to earth ground, the likelyhood that you will even get shocked is very slim. I work around 3phase 480/208 all day long, with capacitors 100x the size of anything you will find in an amplifier and the smallest box we have has over 40 of these capacitors, and I have yet to hear of anyone ever being killed by them. Ever. Shocked maybe, but not killed. My electronics instructor in the service used a cap about the size of a D cell battery taped on the end of a pointing stick to wake up sleepy students. He had a little charging station he made for it, and since we all had nice short haircuts, when your chin hits your chest your neck is wide open, POW, your up. Better than any energy drink or caffiene tabs. Pretty sure none of us died, and that was about an inch away from the spinal cord.

A good point has been made here though, be smart and don't touch anything else on the chassis while you snug the sockets. While others may disagree and say its a cap, it fixed my 400+ lickety split, no sh!t. Oh, and did I mention before that this is something you could try and it won't cost you anything but a little time whereas an unecessary cap job will set you back a week at least and a few hundred dollars. Hmm, what should you try first?

Yes the voltages inside a tube amp and accessible at the power tube sockets are potentially lethal. The fact that your instructor was a fool with dangerous tendencies doesn't change that one whit! Suggesting that folk do their own repairs without any idea of what they are actually doing is foolhardy at best.

OP, take your amp to a tech and get it repaired. His bill will be much less than your life is worth.