Tube Question Channel 2

[pivot]

Ok I know this was prob answered somewhere before but... Its been 1 year since I replaced the power tubes and I never replaced the preamp tubes. We play 4 days a week 2 hours or more a day. Channel 2 while playing will sputter and sound staticy randomly. Any ideas other then power tubes which ones to replace? The manual said slot 2 and 3. I have a SPAX7-A spare I can put in the amp too. I just want to keep the sound the same as it is now but with reliable tubes that keep me in warranty. Should I replace all preamp tubes or leave the others alone.

 

[pivot]

I was looking at the tube store at the combos for the mark V are the tubes better then the ones shipped with the head and will it still be covered under warranty?

 

[pivot]

I spoke to Mesa 800. The support they offer is incredible answered tons of my questions. No need to reply going to stick with the stock tubes and work from v1 to v3 to find the problem.

 

[4406cuda]

I highly recommend Tungsol 12ax7 preamp tubes.

 

[pivot]

4406cuba. I will give those a try. Do you need to replace all preamp tubes or can they big mixed? I broke a SPAX 12ax7 trying to put the tube cover on last night freaking sucked. The top little glass part came off.

 

[jmontgomery]

I have a Tungsol in V1. I did the same thing, broke the glass putting the cover back on. It's a pain but thankfully it shouldn't need changed for a while.

 

[pivot]

Glad to hear it wasnt just me I ordered another SPAX 12ax7 to put into 1a. In the future if I get a different type of tube like the tungsol can you mismatch preamp tubes. tungsol in v1 and mesa in the other slots. Sorry if this is a dumb question just want to make sure not to mess anything up I love the sound I get out of the tubes in the head now.

 

[jmontgomery]

You can mix preamp tubes. Power tubes need to be matched.

 

[SteveO]

Preamp tubes can last for a VERY long time (as in decades). I have a pair of RCA 7025s in one of my rack preamps that I installed in the early 90s, and they're still doing well.

 

[pivot]

I hope that once I replace v1 with the spax7 that will be all I have to do for a long time as long as I can get the metal cover on it right this time damnit. Its really hard to put that cover on V1. I had an old ruby 12ax7 laying around I tried in v1 and man it made my amp sound like it was farting compared to the mesa tubes. Im going to try a tungsol later down the road. Any suggestions on how to install the tube cover for v1 without breaking the glass at the top of the tube?

 

[bandit2013]

Funny you said it sounded like it was farting....
I have a Ruby (HG version) in V1, it sounds terrific. EH tubes in all other locations except for V7 which is a Sovtech LPS. Which works for me quite well. I rolled for quite a while until I was pleased with all channels.

I did like the Tung Sol in V1, but it provided more bass than I needed since the power tubes provide enough bass (GT6L6R-2 [SED wing C]).

Tung Sol is a great 12ax7 tube. It will warm up the clean channel and enhance the higher gain channels considerably. It all depends on you Power tubes, speakers, and guitar. My two main axes are walnut, so they are deep in the low end as well as bright. I also had to take into consideration all of my other guitars as well, each has its own distinct sound. Couple that to a final tone from an EVM12L 412 recto cab.

 

[pivot]

That makes since. Im really pleased with the stock tubes overall. My Guitar is a handmade one off from http://guitarlogistics.blogspot.com/2011/10/s9063-spazmatron.html Korina/Cocobolo and Flamed Myrtle Wood top. The cab is an older 4x12 Mesa cab with the back sealed and Black Shadow c90's in it. The tone to me is perfect When I play my Gibson LP through the head and cab it still sounds incredible. I tried some older Russian tubes they sounded incredible but I think mesa got it right with the tube combo they ship the heads with. Im getting ready to install the SPAX 12ax7 in V1 this weekend if I dont break it. Any ideas how to put the cover on the 12ax7 in v1 without breaking the tube and taking out the reverb tank?

 

[Vittrup]

That makes since. Im really pleased with the stock tubes overall. My Guitar is a handmade one off from http://guitarlogistics.blogspot.com/2011/10/s9063-spazmatron.html Korina/Cocobolo and Flamed Myrtle Wood top. The cab is an older 4x12 Mesa cab with the back sealed and Black Shadow c90's in it. The tone to me is perfect When I play my Gibson LP through the head and cab it still sounds incredible. I tried some older Russian tubes they sounded incredible but I think mesa got it right with the tube combo they ship the heads with. Im getting ready to install the SPAX 12ax7 in V1 this weekend if I dont break it. Any ideas how to put the cover on the 12ax7 in v1 without breaking the tube and taking out the reverb tank?

I've done the same thing, breaking the tip of V1.
Subsequently, I take the amplifier out of kabbinettet. It's not the big problem.

 

[bandit2013]

Subsequently, I take the amplifier out of kabbinettet. It's not the big problem.

I would also recommend removal of the chassis. Perform this on a table, not on top of the speaker enclosure since the last thing you want to happen is to drop the amp chassis.

You will need a 5/16" and 1/2" box wrench to loosen the transformer support.
If you have the metal cage: Leave all of the tubes in place and do not remove the cage.
If you have the metal bar: remove it, then pull out the first tube closest to the transformer (should be the rectifier tube). This way if the wrench slips on you, you will not hit the tube.

Loosen the top main support screws with one hand while providing support with the other hand. Remove the screws completely.

Use both hands to support the under side of the amp and carefully slide it towards you. Do not pull completely out, just a bit to access the reverb connections.

To remove the reverb connections, use a small flat blade screw driver to slide the white lead off the RCA jack. You can easily remove the dark gray over-molded plug by hand. Once disconnected you can remove the amp chassis completely.

I typically grab hold of both transformers. Once clear of the shell, I invert the amp and place it on the table or on top of the speaker enclosure (upside down). If you want to do a tube roll, now is the time to do it before returning the amp to the shell. You do not need to connect the reverb. However if you want the reverb sound in your tube roll, you will need to remove it from the shell. Getting it back in can be difficult, but if you use toothpicks with the decorative plastic curls on them, they work great to restack the spacer and bushing and it makes it easier to place the tank on top, remove one pick to install the screw, etc....

Working with the chassis out of the shell, makes it easier to remove the tube covers and install them. You also do not need to fish for the proper orientation of the preamp tube since you can see the socket.

Putting the chassis back it is a little tricky. If you remove the reverb tank, put that back in first. The process is the same but in reversal of removal (that is obvious). The trick is to get the chassis in the right position. You will have to angle it slightly so the front of the chassis gets over the grill, also make sure that the vinyl is not getting in the way. You could always remove the grill but I find it helpful in holding the amp up so I can free one hand to install the screws.

 

[4406cuda]

I was able to change all of my power tubes and preamp tubes in my head with out removing it from the shell or removing the reverb tank. It is much easier to do by standing the head on it's side.

BTW, I am loving the SED 6L6's and Tungsol 12AX7's

 

[cradlefish]

Don't get too locked in on stock tubes. Mesa will always want their customers to go with their tubes which they don't even make. They just test and grade them. They are the same as you would buy from an online tube store. Listen to the others here with tube experience. Your mark v may sound better than you think with other brand of tubes.

 

[bandit2013]

Don't get too locked in on stock tubes. Mesa will always want their customers to go with their tubes which they don't even make. They just test and grade them. They are the same as you would buy from an online tube store. Listen to the others here with tube experience. Your mark v may sound better than you think with other brand of tubes.

I would agree.

 

[mesa metal]

Don't get too locked in on stock tubes. Mesa will always want their customers to go with their tubes which they don't even make. They just test and grade them. They are the same as you would buy from an online tube store. Listen to the others here with tube experience. Your mark v may sound better than you think with other brand of tubes.

I would agree.

i totally second that motion :evil:

 

[pivot]

Ok you sold me next round ill try some different pre-amp tubes. One thing that has thrown me off when I call mesa or read online is the placement of 12ax7's in different positions and not to replace all of the 12ax7's with new ones. I would think if they are tested and meet the same numbers when tested it wouldnt matter which tubes are placed in what order in the preamp stage. Knock on wood the pre-amp tubes hold out for a long long time before having to be replaced.

I replaced v1 with a mesa 12ax7. I ordered a spax 12ax7 that came in later should I leave the 12ax7 in v1 alone or replace is with the SPAX. just wondering.

 

[bandit2013]

SPAX is not much different than standard 12ax7a. However, since tubes of the same type may have different characteristics, gain, noise, microphonics, harmonics, etc... They are selected for specific characteristics before getting final part number. The selection process, takes time and money so they will cost more. It would be best served in V1.

My Mark III had SPAX in V1 and standard 12ax7 in all other locations. I could not tell the difference between the SPAX and 12ax7. There may be some difference in the Mark V. However, it the SPAX is selected from the same stock as the 12ax7a it will sound the same.

There is more to gain from different preamp tubes. Of course the amp is design to deliver a specific tone based on the circuit design, filters, bypass capacitors, feedback, etc... The character is set, but changes can be made simply by using different brand of tube. The primary tone and character of the overall sound is mostly handled by the input tube. Tone controls ;bass, mid, treble are typically in the first to second stage of the amp. A change in V1 will alter tone depending on what tube is used: Tung Sol for instance, based on simple frequency chart, offers equal gain for frequency range. Low noise, moderate gain. EH is similar, but different in frequency response. JJ is not much different than the Mesa 12ax7. There are others too, NOS Mullards, bugleboy, too many to list. The difference is how they sound. If you have overall bright tones you need to reduce, Tung Sol will enhance the lower and mid frequencies to compensate. If you want more clarity, JAN/GE or JAN/Phillips 5751 (lower gain tube that is interchangeable with 12ax7) will provide more headroom, clean up the mud, etc..

It is easier to start with one tube. If you like its tone in V1, how does it sound in other positions, aka tube roll.

Right now, I have TS in V1, EH in all others except for V7 which is Sovtek LPS. I did have high gain tubes in V2 and V3 but they fizzed the distortion too much in CH2. I selected tubes that offered the best sound for the GT6L6R-2 power tubes combined with the speakers and guitar.