Toob Noob needs some help

[jpotts05]

Hi Folks,

I recently purchased my first tube amp, a 5:25 express, and I love it (all 10 hours of playing time!). I have encountered an issue, though. The last two times I have played it, after some warming up, there seems to be a slight throaty hiss (crackle would be way too strong a term) when I play certain notes (frequencies?) on the fret board (whether single notes or chords fretted with those notes). It seems to go away when I put the amp on stand by for a bit and turn it back on, but then returns shortly thereafter. I followed MB's instructions, and removed each EL84 one at a time (while the amp was on stand by) and played it, but had a hard time replicating the issue. Once both tubes were back in, it returned. Neither tube seems brighter that the other. The hiss decays shortly after playing certain notes, but I don't believe it is a noise that should be there.

Since it's brand new, I can always bring it back to the dealer for investigation, but it's a far drive and I'm trying to be a little self-sufficient here. Plus, with my luck, I won't be able to replicate the issue there, and they will look at me all cross-eyed.

If anyone has any tips for me, please respond to this post. Any and all help will be greatly appreciated.

Joel

 

[tonejam]

Hi there!
Check ALL the tubes, all 7 of them, just in case one has worked its way loose in its socket, that's where I'd start.
If you have a spare 12ax7 handy (a good one) I'd also try replacing each preamp tube one at a time, in case one is faulty.
Good luck!

 

[jpotts05]

Thanks tonejam. I'll check out the preamp tube seatings tonight. If there are no seating issues, I think I will bring it back to the dealer to have them check it out, and since I have no spares - snag at least one 12ax7 and EL84 to have on hand. I've read in this forum that it might be a good idea to swap out all the MB tubes. Is this really necessary, and what might it add? Also, would I have to worry about bias issues then? I know these answers may be subjective, but I still like the feedback.

Very much appreciate this forum. I've been playing guitar for about 15 years, but never have had a tube amp, so this is all very new/strange/cool to me.

Joel

 

[THE TUBENATOR]

Joel, welcome to the board! I’m sure that issue will get resolved quickly and you’ll have years of pleasure with that Express amp.
Vacuum tubes can be a little fickle at times. Some tubes may last years while other tubes, same make and model, may only last a short time. With your Mesa amp you have the freedom to change out individual pre-amp tubes (12AX7’s) at will and you can mix them up; however, the output tubes (EL84’s) must be changed out in matched sets for bias reasons. But getting back to the noise you hear, does your amp produce that same sound in both wattage modes? Have you checked for loose speaker of cabinet screws? Certain frequencies can produce resonate sounds with loose items and even items in your house!

Albert~

 

[jpotts05]

Albert,

Thanks so much for the welcome, reply, and advice - I'll take all that I can get! Whenever I make an expensive purchase like this, I get obsessive over getting it going perfect, and learning everything there is to about the purchase - and WOW... I don't think I was quite prepared for all the knowledge transfer that was going to take place with my first tube amp. Last night I slowed myself way down, placed the amp in a good maintenance position and started from scratch. After checking all the seating of the pre-amp tubes, I went back to the EL84-s, and I'm almost positive that it is one of them that is making the noise. The only reason I say 'almost' is that there are times when the noise goes away - especially after reseating the tube, but I cleary heard the noise when it was the single power tube in the amp, and not when the other EL84 was the only one. It's amazing how difficult it was for my son and I to try and isolate where the sound was coming from. Maybe that will come with time. I did not check if it occured in both wattage modes, and that was a test I should have run. I know it did occur in both channels, though.

My thoughts last night were to buy a complete set of new tubes, and use the ones that were stock as spares. After much reading on this board (see obsessive above), several folks have suggested Doug's tubes. I noticed that my clean channel is a good deal noisier than the others, so I was going to ask those folks what set they would recommend. Now I've read everything from "tubes don't make a difference" to "replace those mesa tubes asap", so a great deal of this is subjective, but my concern would be if I was voiding any warranties by using "non-mesa" tubes. Would you be able to provide some feedback in that regard? Along those lines, if I replaced both EL-84-s and one happened to go at a gig, would I have to put both of the originals back in because of those bias reasons?

Thanks again - I'm feeling slightly more knowledgeable each day.

Joel

 

[Furvel]

I recently purchased a matched set of power tubes for my Express, and I kept the old ones (still in fine working condition) as a backup set. In the event of a at-the-show problem, I would swap out power tubes in sets, to be safe.

I recently had a preamp tube crap out, but I just replaced it with a stock Mesa tube. I have seen so many options bandied about in this forum, that my head is swimming a bit. At this time I don't have the financial resources to buy endless amounts of 12AX7's to experiment with, especially considering that I may not like the resulting tone. The folks I talk to locally aren't impressed with the reliability of Mesa tubes. I'd just be happy with a set of preamp tubes that have similar tonal characteristics to the stock Mesa, just more reliable. Then I could keep the stock Mesas as backups.

 

[thunda1216]

If it's new, the tubes should be under warranty. You must also consider that the tubes/amp are checked at the factory. Then the amp is loaded on a truck and bounced all over the country to another shipping point, then man handled into another truck and bounced to the dealer...then who knows how it was handled before *you* got it...then if you didn't hit any potholes going home with it...the tubes are fragile to start with, and some just can't handle all the jostling (UPS does NOT care how they handle packages) I'd take it back and ask for replacement tube(s) under warranty before it expires!

ty

 

[THE TUBENATOR]

I have to agree with thunda1216, there is no telling what your amp had to endure during transit. I have visions of the old television commercials with the Samsonite Luggage Gorilla testing the new luggage by throwing it into a cage with an 800 pound Gorilla and having it banging on the ground and tossed up in the air! Just because the outside of the box has no visible damage that does not mean the contents were not shaken up.

As far as the tube selection goes….it’s purely subjective. There are guys on this board who swear by one brand or combination of brands and those who feel differently. I like my Mesa 6L6GC matched tubes and I also like my Mesa SPAX7’s in all pre-amp tube positions. It keeps it simple. V1 – V5 have the same exact low noise (tested by Mesa for low noise) tubes. I always keep a pack of Mesa 6L6’s (one matched set) and at least two of my old SPAX7’s. I have never had a SPAX7 fail. I really don’t know if I would like the tone that is created by the Doug’s tube configuration because I have never tried it and I’m happy so I have no interest and trying it. When I had my old Vox I would simply buy whatever tubes they were selling at either Guitar center or Sam Ash and I did notice some lasted longer than others. I like extreme amp settings so I tend to kill tubes anyway hence the name Tubenator.

 

[floaty83]

Shipping is a *****. I'm surprised that every single package that goes through UPS isn't damaged in some way. I work closely with the warehouse at my company and I can say that I've never met a UPS driver who gave 2 sh!t5 about the packages he or she was delivering. In their defense, I think every single one of us would be the same way after doing that job for a couple of weeks.

 

[jpotts05]

Love all the comments folks. Thanks for taking the time to read and reply. Just got my complete replacement set of tubes from Doug's, including 2 Mullard EL84s which were suggested by Doug based on questions he asked me. As my topic implies, I'm not so sure I'll be able to hear the differences these tubes make, but I now have backups for all my tubes - and yes, if the EL84 was indeed the issue (my gut and ears say yes), I'll be contacting my dealer for a replacement. If they make me bring the amp back up to appease them, I'll just swap the tubes back and make the trek. Wish me luck and I'll post again on Monday to let you know how it went.

 

[jpotts05]

***update***

Did the tube swap this weekend, and as expected, that did the trick. Thanks all.

Joel