Mesa Express 5:25 Loss of Power and Definition

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Always gotta take the internet with a grain of salt though. Keep in mind that there are plenty of people out there not having problems so they don't really need to write anything about it. As soon as there's a problem though, you come running for help. And maybe a treble bleed is what I remember being mentioned. Dunno.
 
Yes, the odds don't support the theory.

It's still working since I put in the second PI tube and it went though a gig since too. In fact, what the hell am I doing here anyway? I've got no projects to work on, I'm gonna go play. :mrgreen:
 
Well, since stumbling on the bad PI and learning how to break them, or I mean avoid breaking them, the amp has been fine for the most part. I pretty much run the fan all the time now.

So anyway, there's a lot of good sounds in this amp even with the volume down really low and up really high.

The red labeled EL84 output tubes Mesa spec'd are working well. I'm back to the original red set. Seems the bad PI is what I heard or they were overheated, but not ruined.

The preamp tubes are:

V1: EH 12AX7EH
V2: Tung-Sol 12AX7
V3: JJ ECC83 S (12AX7)
V4: Sovtek 12AX7LPS
V5: Mesa 12AX7 (Looks like a JJ)

The difference the Tung-Sol made was remarkable. I saw a lot of folks say that and wondered. Well, it's the real deal.
 
Those Tungsols are very good. I have not found a a nicer new production tube yet. I had one in the PI slot for a few months, but took it out as the reliability is said to be problem if used a PI tube and I wanted to a slightly warmer sound. A JJ long plate has been in there since, which I think is also not recomended for combo amps. The JJ long plate does not sound like the regular JJ tube, it is more light the Tungsol, but warmer.
 
I went for the Sovtek based in the PI article many of us read. The PI seems to get really hot in my express, so I want a tough tube and I'm running the cooling fan too.

The Tung-Sol in the V2 position of the Express seems a natural for what I expect to hear. I'm thinking two or three of them might be a bit too nice.

I wanted to stay close to what I had working while upgrading what I knew was old and or bad. So the JJs were in there and working and I had an EH that was good too. First I had Tung-Sol in 2, JJ in 1 and 3. Then I tried the EH in 1.

The EH in V1 gives more of an 80's rock sound. The JJ in V1 gives the amp a warmer thicker blues sound. But I can roll the guitar tone back and get that warm blues sound with the EH, so the EH is in V1.

I'm enjoying my Express again. A couple more successful gigs and I'll be way relaxed. This past week we played Gary Moore - Oh Pretty Women and I got a tone compliment for my solo. That was cool to hear. I did try to dial into that lead sound and it's cool to know others heard it too.

Yeah I know, useless without clips. :p

Fan Pic:
gallery-image-506-1292536515.html
 
The jam Sunday went well. I has no problem hearing myself and there was a Marshal 100 Mosfet with a 4x10 next to me. Can you say ear plugs?
 
Low gain or high gain, which way did he go?

Despite the last posts, the last 6 months or so I have had a set of EH tubes in my Express v1 v2 and v3. They were put in there to be left and forgotten about. I needed to stop fucking with gear and play. I did. I played and listened and learned and compared. I was playing clean mostly and honing my chops and ears.

Long story short, the EH tubes turned out to be way to low gain ( or bad ) and I needed a boost pedal to get some distortion and sustain. It didn't click for a long time that there might be something missing cause I was playing clean mostly. But none of the high gain players at the jam wanted to jam the little mesa anymore. The burn channel was just compressed mush. No sustain.

It became obvious there might be a problem when I got to where I could solo and needed the gain and sustain, but didn't have it. I knew it was there and blamed the guitar as too low output and used a boost. But there was still something missing.

So since I had been good and took the time to learn the amp with one setup, I thought, OK, let's see if you have learned to hear anything and swapped out v1, v2 and v3.

Like disco lemonade there she was! Gain, volume, swirl, sustain.

I have a mesa JJ in the Reverb v5 and a Sovtek LPS in the PI v4. I put a Tung-Sol in v2, a Sovtek in v1 and a JJ in v3. It sounded amazing.

But low and behold, with that much gain, I had the volume drop out like I had that started this thread eventually after playing a while. Switching the face plate channel switch from Ch1 to CH2 and back fixed it this time. It was dramatic and obvious that there was a drop out and then a return of full volume.

The only thing in common with then and now was the amp and that one JJ tube. So out it came and in went a penta labs Chinese. The amp still sounds awesome, but let's see if this volume drop issue was a tube or the amp. If it's a tube, the problem is gone. I hope it was that JJ tube. The whole batch was crap it seems. I hope it's not a heat issue because of using the front end completely because mesa couldn't duplicate it when they had the amp. The tube being the issue makes more sense in light of that.

Thanks for reading.
 
I have had the volume drop out a few time practicing and thought, yeah, maybe it's me. I can't believe I allowed my self to be talked out of hearing a problem.

Yesterday at a show the ugly drop out showed itself. I was playing on the green channel, switched to the red channel for a solo and when I came back to green, she lost volume. I cranked the guitar and the amp main, but it would not get louder on the green channel. It was no where near where it should have been in volume.

I stomped the switch to red, bam, she was red channel loud. Switched back to green and she had full volume again.

So yeah, there is an issue and I can't replicate it on demand. So how do we fix it? It's been an ongoing thing now since I got her. (Thinking out loud.)
 
How did it end?

This is an old thread that has been left suspended over our heads. I just bought a 5:25 so I'm obviously interested in knowing what happened, man!
 
The amp is working well. I can't duplicate that issue on demand. So I changed out a tube or two for lack of ability to do much else. All is well. I'm really happy with the amp for how I use it.
 
Well, she fell on her face during a show again yesterday.
All was good, switch to do a solo and nothing.
Reached back for some master volume and nothing.
I turned it all the way up and got low volume.
Usually it will start squealing before 3 oclock.
There was no sustain.

It's been several months, so I will look at the OTs.
But it seems to have to do with the channel switch and front end IMO and not tubes in the front end.

Anyone else gigging a Mesa Express 5:25?
 
Put in my last set of Mesa EL84 Red and she is jangling and loud.

I think it's time for the cooling fan again. I had stopped using it in the winter and at venues where it is a comfortable temperature even on stage. But Sunday is the real workout day for the amp and it was hot. Looking back we have been here before and the fan should solve the problem. The OTs were well used.
 
I wonder if you are shorting tubes?

I had my OTs replaced under warrantee when , in the lead channel the amp would loose power and fizzle. Looking in the back, one tube was glowing more than the other (this was in 25 watt mode). It only happened when it was in 25 watts.

Switching it to stand by then back again fixed it.

It was traced to a shorted tube.

I am now careful to at least switch to stand by when switching between modes. Seems to help the tubes deal with the configuration switch.
 
One OT glows more then the other in 5 watt mode. And I have been trying 5 watt mode and even going with the the 8 ohm speaker in the 4 ohm slot. Playing a lot too. So maybe it was time since it came back solid.
 
FXR said:
One OT glows more then the other in 5 watt mode. And I have been trying 5 watt mode and even going with the the 8 ohm speaker in the 4 ohm slot. Playing a lot too. So maybe it was time since it came back solid.

That's normal. But I swear that the EL84's are sensitive. Taking care to be in stand by when switching wattage and periodically switching tube sockets if you play in 5 watt a lot helps the tube life. I Love them, but think the EL84s are prone to a short-type failure mode.
 
My amp is working well. Tube quality is questionable. I do really use this amp a lot for a jammer and can almost always play it with the master volume up pretty good. So I guess I will go through tubes as I have. I just don't use 5 watt mode anymore as it just uses up the tubes too fast IMO.

The power lamp burnt out, easy replacement. But the fish eye lens fell off the burn channel red LED and I can't do anything with that.

I have a Mesa 2x12 vertical I am trying and it makes this amp sound amazing. The 1x12 is cool, but the cabinet is rich with bass with the closed bottom I assume.
 
A single pair of El84 tubes as in the 5:25 do get pushed quite hard electrically. the other issue though is that the vibration from the combo chassis is not kind to them either. It a had life for an EL84 in an Express 5:25 :cry:
 

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