Mk V Combo - New Amp Problems. Fixed. Then broken again.

[Tofty]

Howdy folks,

Bought myself a brand new Mk V combo yesterday. Spent a few hours dialling in my sounds and got a great tone out of it. Everything was way too toppy by default and I ended up with the treble/mid pretty much totally off on the crunch channel, which felt like a strange place for the knobs to be, but it sounded good so didn't think any more of it. I play a fairly standard rock tone with a reasonable, but not extreme mid scoop.

Switched it on again this morning and the fuse popped. Went back to the dealer and got another fuse, same again.

Dealer is going to get a full set of valves in ASAP to change them out in case it's a dodgy valve. Does this sound like the probable cause? Could it also be in any way connected to the massive overdose of top end in the EQ?

Having just traded up from a very happy 3 year relationship with a Blackstar Series 1 I'm a bit disappointed at the moment :-(

Here's a pic of the settings as they were when it popped. Could anyone comment as to whether this looks remotely like an amp should with a great sound dialed in? It doesn't to me.

 

[farren]

I could be wrong but I believe extreme EQ settings should only offer a threat to speakers that can't handle insane boosts at either side of the spectrum. I don't think that's you based on your settings.

Your settings look nothing like my settings (most people keep channel Masters between 9 and 12:00 to avoid too much pre-amp side distortion which can over-compress, and they'd use more Treble, less Presence, and few people dime channel 3's Gain, but what you're doing is still kosher) and to answer your question, no, I don't think those settings would sound good at all, but you can do whatever you want with your preamp settings. Also, most people do use the channel 3 bright switch, but that's entirely personal.

Most people keep treble 10:00 to 2:00, mids at least at 9:00, and bass at least at 9:00 (Mark I aside). Presence is rarely past 12:00. Gain to taste.

I can't tell what wattage they're all set to, but if channel 2 is on 45w, were you using tube rectification or solid state diode? It's on the back under channel 2's reverb knob. I was thinking it could be a rectifier tube problem, but if you weren't using channel 2 45w with tube rectification when it happened, I doubt it is. What channel were you on when you turned it on and the fuse blew? It's easy to rule that possibility out.

Next thing I'd think was power tube problem.

After that, warranty service.

By the way, that's not too much top-end. I have 6600 hz set about the same as you and a little more 2200 than you're using. Similar settings are fairly common. When you get it fixed, experiment with variac power as it takes care of some of the scooping for you at quiet volumes so you don't have to overcompensate with the pre or EQ settings. IMO full power doesn't sound great till you crank the output a bit.

 

[Tofty]

Thanks for the comments. I sat there A/B-ing with my old Blackstar and playing around until I got a similar-ish tone. Then obviously because they're totally different amps spent another few hours playing with the Mk V as it has, well, lots of options! The clean channel is on 90w (for the headroom so it stays 100% clean at gig volume), the others on 45w which is more than enough for the size of gigs I play.

I've only had it for a day so am a long way off mastering my sounds, but it did sound great until it went. I can't remember which channel it was on, I flipped the master on this morning and it just died. I use a Mini Amp Gizmo to MIDI switch from my One Control OC10 looper.

Just felt a bit strange having Ch2 treble/mid completely off to be honest, but if that's the way it works then that's the way it works.

 

[farren]

Since you were playing 45w mode, see how the channel 2 rectifier switch is set so we can eliminate rectifier tube as the culprit. If it's on diode rather than tube, it's not the issue. It's possible it isn't regardless.

Regarding treble/mids, if that's the way it works for you, little else matters

 

[screamingdaisy]

Presence typically controls an area in the high midrange. Having the presence that high is likely why you're getting such a bright sound.

Additionally, confirm that the FX loop send knob in the rear is set around 12:00. If it's turned up too high it'll sound really bright and distorted.

Lastly, the channel master affects how hot the signal that's being sent to the effects loop is. As you increase it you start to overdrive the FX loop (and any devices plugged into the effects loop). Try bringing them down so that channel 3 is around 9:00 to 10:00, then adjust the other two channels so that the volume matches.

 

[Tofty]

All the switches are set to tube, although not having any more spare fuses I couldn't test it anyway. I've ordered a 10 pack of fuses, so it they arrive before the tubes get the dealer I'll try the recto switch on diode just to rule that out.

The FX loop is set to full negative as I was getting breakup on the clean channel with it at 12 o'clock. Nothing too unusual in the loop at present; Wampler Chorus/Delay/Verb, in that order.

Again, thanks for the comments. If the new tubes from the dealer sort it I'll definitely be trying your suggestions.

Alex

 

[screamingdaisy]

The FX loop is set to full negative as I was getting breakup on the clean channel with it at 12 o'clock. Nothing too unusual in the loop at present; Wampler Chorus/Delay/Verb, in that order.

That might be from the high channel master setting. If you bring them all down you should be able to get a better balance.

 

[farren]

The FX loop is set to full negative as I was getting breakup on the clean channel with it at 12 o'clock. Nothing too unusual in the loop at present; Wampler Chorus/Delay/Verb, in that order.

That might be from the high channel master setting. If you bring them all down you should be able to get a better balance.

Definitely... I start getting break-up on Fat around 11:30 Gain and Master.

Edit: Assuming you can dial in proper input and output levels on the gear itself in your fx loop, it's really a good idea to keep the fx loop level at noon, or very close to it. I only have a G-Major 2 in my loop, but with the input and output knobs on the device itself carefully calibrated and the amp's fx loop set to noon, my dry sound sounds the same if I have the unit in the loop or not. The Mark's loop is a good one and if you have decent gear to put in it, you'll get no noticeable tone suck.

When you get your amp working again, I recommend trying some known-good pre-amp and EQ settings to see what this amp can really do, then tweak from there to find your own tone. I can't vouch for recommended settings in the manual, but you'll find plenty on this forum or on the sites of endorsers like John Petrucci.

 

[Tofty]

Good news is the dealer just swapped it out for a boxed replacement. Gigged it last night and it sounded great. Being able to EQ each channel individually made a big difference compared to my previous amp as I used to have issues with too much bass on clean and not enough on dirty. Anyway, it's all good.

Obviously it sounded considerably different at high volume than it did setting up at home, so I think an evening at the rehearsal studio might be time well spent to get it sounding perfect at volume.

 

[Tofty]

The new amp lasted a couple of weeks and 1.5 gigs exactly. Then it decided to blow a fuse half way through the set tonight. Changed the fuse, blew instantly. Exact same symptoms as last time. Thankfully the owner of the venue had an old Fender so I wired in a Wampler Pinnacle for the night and all was not lost.

Feels like there's a major quality control issue with the current batch of Mk V combos in the UK. It'll be going back to the dealer yet again for a replacement, but I'm really pretty angry right now so this is the last chance before I give up on Mesa.

 

[bandit2013]

If you are blowing fuses, trick to determine cause if tube related; Process of elimination method: You can also find this method in your owner's manual.

Leave the switch in standby, and power off, you can remove the power tubes on at a time and turn on the power switch. If there is a short in the heater element of the tube, it will blow the fuse. I would start with the 5U4G. remove it and turn on the power switch (STANDBY switch must remain in STANDBY). If the amp lights up and remains active, you have a short in the diode tube. It does not matter if you use this tube or not. If you blow a fuse with the diode tube out, put it back in and repeat for the other power tubes (removing one at a time). You will need 5 fuses rated for 4A slow blow type. If you get through all the large tubes and blow fuses every time you turn it on with one of the tubes out, problem would be related to preamp tubes. It is more than likely related to power tube than preamp.

I retubed my MKV. I even ordered a new 5U4G. I had issues with the power tubes and not the diode but wanted a spare. I wanted to check all of the tubes, they worked fine. Then I replaced the original diode tube with a new one, blew the fuse. I had plenty of fuses in my inventory of parts, returned the original 5U4G into its socket, no problem.

 

[Tofty]

Thanks for the suggestion. I've got a big box of fuses I ordered after the first amp died so I'll try that in the morning.

 

[Tofty]

So you were right first time. Take the recto tube out, change the fuse, it comes on clean and stays on. Put recto tube back in, switch on, big flash in the tube and all goes dead.

Incidentally all the channels were set to diode rec when it blew with 90/45/45 power settings, so whilst the presence of the bad recto tube would always cause a fuse blow regardless of rectification settings, does that mean if it happens again and I don't have a spare that I could literally just take the tube out, change the fuse and carry on playing?

 

[ricorocks]

So it seems like you're also having a PITA with these amps eh??? WTF i am going through hell with my new V head. I hope to get everything resolved otherwise i'm giving up on Mesa and heading for other Routes. i really wanted to love this amp and really believed i would be satisfied and that my gas for high end Quality Amps was over But.........Guess what!!! :evil: :evil: i think you have your master and éPresence volumes way high and NO MIDS?!? also to much bass rolled in on ch 1 fat, try rolling it back a bit, your EQ setting is NOT extreme at all. Good luck man :|

 

[Tofty]

I wouldn't pay too much attention to the settings up top, that was after I'd had the first amp for a day so it was only an initial setup at bedroom levels. Interesting to see the build date of the amp was August 2011... makes me wonder where the hell it's been for the last 20 months. Given that amp 1 and amp 2 were almost sequencial on the serial number it makes me wonder if there was a bad batch of recto tubes or something.

 

[MrMarkIII]

It's a very bad idea to just keep replacing fuses without fixing the problem. A blown fuse is telling you there is something wrong with the amp, and the fuse blows so that more expensive parts don't blow.
If you don't fix the problem, and just keep sticking in more fuses, eventually those more expensive parts will fail, too. The blown fuse is telling you something. Listen to it.

 

[Tofty]

You've lost me. This is 2 new Mk V amps we're talking about. First one went straight back as the dealer didn't want to start trying to diagnose it. Second one has been diagnosed as a faulty recto valve by using the approach mentioned earlier, and also by reference to Mesa's troubleshooting page on their website. They specifically recommend systematically removing valves and blowing fuses to find the faulty tube.

New recto tube in the mail, where's the "not fixing"?

 

[bandit2013]

When I retubed my Mark V, and opted for a new rectifier tube, all was in good order except for the rectifier tube. I bought a dud. One of the rectifiers had a short circuit. Fuse would blow immediately. At least the original Rec tube was fine. Tubes are durable but are sensitive to shock/vibration.

Hopefully you get your Amp up and Rocking. It is no fun when it lets you down. My amp is not very old either, I could have had the tubes replaced under warranty. I believe the original tubes carry a 6 month replacement period.

 

[Tofty]

Hi, yes it's all back up and running and been sounding great ever since. The UK distributer were very good about it so can't fault the customer service.

Having never had a valve go on me at a gig, ever, I did unsettle me a bit. That said, I've had it from the horses mouth that if I'm ever stuck like that again I can just change the fuse and run on diode with the recto valve completely removed. Now looking forward to a long and uneventful relationship with my very expensive amp

 

[tonedragon]

Your running channel 2&3 with the gain dimed all the time? the louder you play the longer you play the harder it will be on that amplifier and you will eat up tubes and blow fuses.


If you back off the gain a little and not use the rectifier all the time you should be good .