Problem with playing my MK V at really low levels

[Nermel]

I turned up my MK V to a very low, only audible to me, level while in 90 watt Channel 3 mode...about 15 minutes into playing the two power tubes started get really hot and and turn red...the amp started to hum really bad...I turned the amp to standby and allowed the tubes to cool...and then turned it off and allowed them to cool for a half an hour...they seem to be fine now...BUT...I think I did some damage to the Power tube closest to V1...it has blue flamage around the top and bottom of the tube...

should I replace my tubes??

 

[JAZZGEAR]

I would.

 

[MusicManJP6]

Why didn't you kick the power down to 10w for those volume levels?

 

[Anonymous]

I turned up my MK V to a very low, only audible to me, level while in 90 watt Channel 3 mode...about 15 minutes into playing the two power tubes started get really hot and and turn red...the amp started to hum really bad...I turned the amp to standby and allowed the tubes to cool...and then turned it off and allowed them to cool for a half an hour...they seem to be fine now...BUT...I think I did some damage to the Power tube closest to V1...it has blue flamage around the top and bottom of the tube...

should I replace my tubes??

this is a nice article about power tubes glowing blue http://www.thegearpage.net/board/showthread.php?t=462002&highlight=power+tubes+glowing+blue

if your amp is running normal, i wouldn'd worry about replacing anything. in the other hand. if you continue to see the power tubes turning red then i'll be calling my mesa rep.

also do you use the fan?

hope that helps :wink:

 

[screamingdaisy]

The red was redplating. It's usually indicative of a bad power tube or a poorly seated power tube. Give each tube a firm push down into the socket to make sure it's seated right. Power the amp up, and while powered up give each power tube a flick with your finger nail a couple of times (don't be afraid to flick it firmly, but don't hit it so hard it's pushing sideways). If one of the tubes makes a loud crashing sound when you flick it it's mechanically damaged and will need to be replaced.

Other than that, there's nothing wrong with playing a 90w amp with the volume barely cracked.

 

[Nermel]

Ah thanks for the replies...yes I do keep the fan on...so don't think that was the problem...ah and I played it at 90w that low because...well...I didn't think about it...so eh my bad...still don't think it should do that...but I think that's the reason

 

[phyrexia]

Redplating = Bad Tubes

Get thee to a service center and they should be able to replace your tubes under warranty.

 

[Nermel]

Redplating = Bad Tubes

Get thee to a service center and they should be able to replace your tubes under warranty.

I called my Dealer but they wanted to call Mesa and find out what the Power tube configuration was first...they hadn't spent enough time with the MK V to know themselves...despite the Head that they JUST received the only other other MK V they had was combo in May (which was mine which was on preorder)

 

[phyrexia]

I called my Dealer but they wanted to call Mesa and find out what the Power tube configuration was first

Nevermind, I saw a post on your other thread. That's silly of your dealer, considering that information is widely available. :?:

Which power tubes were redplating initially? You didn't say which two.

 

[Nermel]

Umm...the one closest to V1 was the worst...and the one next to that redplated but not as bad

 

[phyrexia]

Looking at the back of the amp,

Recto Tube | Tube A | Tube B | Tube C | Tube D

Which one was it?

oh, and what power setting were you using?

 

[Nermel]

Looking at the back of the amp,

Recto Tube | Tube A | Tube B | Tube C | Tube D

Which one was it?

oh, and what power setting were you using?

Ah...It was Tube D that was the worst...and tube C redplated a little....

I was using 90w...Full power... not variac

 

[MarkIVwidebody]

45W

 

[Octavarius]

I turned up my MK V to a very low, only audible to me, level while in 90 watt Channel 3 mode...about 15 minutes into playing the two power tubes started get really hot and and turn red...the amp started to hum really bad...I turned the amp to standby and allowed the tubes to cool...and then turned it off and allowed them to cool for a half an hour...they seem to be fine now...BUT...I think I did some damage to the Power tube closest to V1...it has blue flamage around the top and bottom of the tube...

should I replace my tubes??

The shouldn't be ANY issue with running the amp low in 90W. Most will probably use the 10W setting for those levels as it might sound better, but you shouldn't get any power tube failure on any power setting on any level.

Obviously tube "D" suffered from a severe short (with blue arching, etc.?), and that one (as Mesa also state in the manual) is what most likely caused it's neighbor to red plate as well. This is normal, and the other tube might be completely fine. I'd replace the one tube (with it's corresponding matched mate) and keep monitoring the amp. Unless you've got really bad electricity in your home, I'd say it simply was a bad power tube. Every Mesa tube has a 6 month warranty, so you should have no issue with getting the pair or the whole quartet replaced. If not through your dealer, call Mesa.


And for further info:

1. As a general rule, SOMETHING must have caused the power tube short. It could have been a faulty tube itself, or perhaps a spike from your mains power, etc. In any case, if you need the amp to be reliable (e.g. upcoming gig), always replace the faulty tube, and keep more spares at hand if you gig. Same goes for fuses.

2. The blue flamage you see is actually completely normal. It's simply cobalt impurities on the plate that light up. Every new tube will most likely have a noticeable blue glow at the top and bottom (and sometimes the center). This is also a good indicator to what tubes are currently active (e.g. power setting), as when they are "off", only the heaters glow (orange).


Does the amp still make those "scratching"-noises in Channel 1, btw?

 

[Nermel]

Ah thanks for the great info...ah and yes it still makes the scratchy noises...I've concluded it's not the footswitch or the cable...I'm replacing my P. tubes as soon as I recieve them from Mesa...and I have a new preamp tube from mesa I will probably swap through each preamp socket to make sure it's not them

It's not that big of a deal (the scratchy noise) just enough to get on my nerves

Any other ideas???

Thanks in advance

Ah and if my electricity is bad in my house...what should I do? A power surge protector or a power conditioner (lol)?

 

[Octavarius]

Ah thanks for the great info...ah and yes it still makes the scratchy noises...I've concluded it's not the footswitch or the cable...I'm replacing my P. tubes as soon as I recieve them from Mesa...and I have a new preamp tube from mesa I will probably swap through each preamp socket to make sure it's not them

It's not that big of a deal (the scratchy noise) just enough to get on my nerves

Any other ideas???

Thanks in advance

Ah and if my electricity is bad in my house...what should I do? A power surge protector or a power conditioner (lol)?

About the static noises, check out my thread in the Lonestar-section. I'm experiencing something similar.

To check if it's the preamp tubes, you can just turn down the main master output control. If the noises are still there, it's something after the preamp and effects loop stage that's the cause. Most likely power tubes or input power.

A power surge protector can do only so much. A good power conditioner from Furman would probably be a better investment. Check out their compact power conditioner (that little box). Should do the job perfectly if you just want to use it for your amp. Before you buy anything expensive, though, try running it at a different house (preferably with known good power) or at a venue and see if things change. Or get a multimeter/voltage meter and test the voltage coming from your wall socket. Note that this could be highly dangerous if you don't know what you're doing, so you might also leave it to a pro.

 

[MarkIVwidebody]

Ah thanks for the great info...ah and yes it still makes the scratchy noises...I've concluded it's not the footswitch or the cable...I'm replacing my P. tubes as soon as I recieve them from Mesa...and I have a new preamp tube from mesa I will probably swap through each preamp socket to make sure it's not them

It's not that big of a deal (the scratchy noise) just enough to get on my nerves

Any other ideas???

Thanks in advance

Ah and if my electricity is bad in my house...what should I do? A power surge protector or a power conditioner (lol)?

FYI, surge protectors, which most people don't know, only protect against slight every day surges in power that come into your house. If you get hit by lightning, for example, the surge protector is like an orange barrel trying to stop a speeding train-won't help at all. Always unplug your stuff during a lightning storm. Many t.v.'s get blown like this.

 

[Tuna141]

The "scratchy" noise is most likely tube related - I have had preamp and power amp tubes make strange sounds like this. I think you'll be able to get rid of it by performing some tube swapping. Good luck.

 

[rispsira]

The electricity in my country is very bad, so i have a voltage regulator and then a furman. Once the furman was really helpful when a BIG spike occured because it has a cutoff feature and so stops feeding all your gear with electricity

This is just info that is nice to know and i would advise you to get a power conditionner, even though i am not sure that is the problem (sometimes its hard to predict a tube that will fail and maybe you just got a bad tube)

 

[rabies]

If you don't use a spkr cable from cab to amp, or the wrong ohmage from cab to amp (there are "good" and "bad" mismatches, see the manual), you are asking for trouble and you may experience a power tube shorting and getting very hot like that (it happened to me with my ex-IV).

And don't listen to these guys about "just replace the one red-plated/shorted power tube". Yes you can do that but I recommend to replace (minimally) the pair. If you don't believe me, call Mesa. There could have been damage done to the other power tube in the push-pull pair.

You may want to use a weber bias rite to measure the plate voltage and idle current draw just to be safe.

And definitely call Mesa to request some new power tubes, they're usually pretty good about that.

btw, I've used a Monster Powercenter 2500 for a while now, it's pretty good (shows voltage + many 3 prong outlets) and kills some noises as well.