Mesa MarkV / Saturation 'mod'

[bandit2013]

The Doug's tube order arrived while I was swapping speakers in the Mark V combo. Why not go back to EV speaker at least it is more satisfying than the MC90. Yes, I have a closet full of speakers. Mostly what is in the boxes are the speakers I had replaced. A note about the tubes, Doug has marked each tube with the gain of each triode. Most of them had 105/105 written on them. One was marked with 110/110.

For those in immediate need of the tubes in question NOS Beijing Square foil getter tubes.... they sound identical and a bit better then the old Mesa tubes I had acquired from the Mark III days in the 90's. I also took the liberty to tube roll to see what works and what does not. First started out with all of the new tubes in the Mark V. Very nice on all channels, clean never sounded better, CH2 needed something a bit different and CH3 had no ice. Note that the amp chassis is still out of the cab and sitting on the extension cab inverted along with the reverb tank. I used an extension speaker cable that I made with a female adapter on one end so I can use the attenuator with the combos I currently have. I tried the Sovtek LPS in V7, ok but the Beijing sounded better. I had realized that the 110/110 Beijing tube sounded the best in the PI (V7) position. So I do not bore you with details this is what I found using the Beijing tubes and others to meet my liking..... V1, V3, V5, V6,and V7 Beijing, V2 Mullard CV4004 (worked the best on all modes on CH2, primarily Mark I and Crunch). And the Jan/Phillips 12AT7 in V4. That actually set the bar much higher than expected. The Mark V now roars like it should. I did try the JAN/Phillips in V6 as well but found the clean channel seemed a bit muddy (I did not take the time to adjust the tone controls as they were basically set just below noon.) Clean channel with the Beijing tubes sounded more acoustically natural. I still have not tried them with the Piezo bridged guitar yet. CH2 did benefit from the CV4004 as it seemed to scoop some of the midrange but not by much and it also took off the ice on the top end. CH3 is beastly and sounds much better with the JAN/Phillips 12AT7 in V4. Nice tight, thick and juicy tone that just makes you thing "Oh Yeah" in a deep sultry voice. So much for being the guinea pig on the Beijing tubes. I am glad I decided to get them as the old Mesa tubes have seen better days (most of them have dark areas on the glass between the two top mica spacers that has a slight metallic hue to it, I also have one that was in the spare tube holder that never got used odd that it did not have any printing on it. Its All good now. At least I have 5 more to use when these burn out or find use in another amp....say where is the JP-2C....well someday I might. The NOS Beijing tubes, yes they are as good as the old Mesa tubes

 

[Dreamtheaterrules]

Remember that this mod gives you a lot more potential, but its in the dialling. Was the FX loop active? If so what was it set at? There are a more variables and perhaps setting requirements on the big head. Rest assured, the brutality is there to be had.

Loop on, at noon like it's been for a while.

Session 2 tonight. I think there is a very minor improvement in C3. Not the glorious transformation that happened in the V25! Either the great old tube made all the difference, or it's time for other new tubes. After Bandits post below, I'm probably going to really surprise Doug with my order. LOL

 

[bandit2013]

Remember that this mod gives you a lot more potential, but its in the dialling. Was the FX loop active? If so what was it set at? There are a more variables and perhaps setting requirements on the big head. Rest assured, the brutality is there to be had.

Loop on, at noon like it's been for a while.

Session 2 tonight. I think there is a very minor improvement in C3. Not the glorious transformation that happened in the V25! Either the great old tube made all the difference, or it's time for other new tubes. After Bandits post below, I'm probably going to really surprise Doug with my order. LOL

Leave a few left for me as I am thinking on getting some more.... Once I try them in the JP-2C and if it is a hit I have a few amps to get tubes for.... :roll:

 

[bandit2013]

Yeah, about the Beijing tubes in the JP-2C... the amp sounds fizzy with those. I have heard that comment before but never experienced the fizz until I tried them in the JP-2C. The Mesa branded JJ tubes seem to be the best in that amp. Seems that the converse is true as I found similar fizz with the Mesa branded JJ tube in the Mark V. The Beijing tubes do make a difference the Mark V (90W version). I also heard they work well in the Rectifier amps so that will be next. At least I have a few years supply for the Mark V in terms of preamp tubes. I also like them in the RA100 too.

Since I got the amp put back together I was enjoying all of the channels on the amp The Tweed voice on CH1 sounds great and usable. I did not like it before. Same with Edge voice on CH2 as that sounded like poo but now has a usable tone to it which is just a bit shy of Crunch. CH3 now sounds JP-2C. I will have to run a side by side comparison again. The 12AT7 is a keeper in V4 and is a must for the JP-2C tone, heck it just sounds better, period. Fresh new tubes always makes a difference.

 

[Bankim]

Thought I'd do a video with the 12AT7 in V6. Don't have a recording set-up at home so its recorded using my Note 5.

https://www.youtube.com/watch?v=mDLozNfO13U&feature=youtu.be

I haven't played for a couple of weeks so ignore the clams. It sounds much better in person but hopefully this vdo gives an idea ...

 

[bandit2013]

I found this while looking for other 12AT7 tubes.... The Mesa 12AT7 would be comparable to the Sino 12AT7 (was the only Chinese version on the chart and also has the plate clips). It is indicated as being bright where as the JAN/Phillips is more neutral. If the chart does not pop up, select the 12AT7 near the top.

https://www.tubedepot.com/tube-comparison-tool

Based on what my ears tell me (just using it in V4) the Mesa 12AT7 is much brighter than the Jan Phillips for some reason that was closer to the stock 12AX7 but was better. This may all be subjective at best. I prefer the warmer tone of the JP-2C and my reasoning for the JAN/Phillips has me stocked. Couple that with the Beijing tubes in the Mark V and now it is spot on. No more hum on the clean channel, CH2 sounds better (tuned with V2 of tube choice). I only wish I could find a current production 12AT7 tube that is similar to the Beijing tube (old stock Mesa tubes from 1980-1990). I have tried others and they just did not compare that includes the 9th gen and other versions. Also they work well in both the Mark V and RA100 but do not seem to be favorable in the JP-2C (fizzy), also including the Roadster (not much of a difference). Still a subjective opinion... The JAN Phillips in V4 just makes it better. The best thing is, I am getting more mileage out of the Mark V (now it is ideal for me.). Awesome with the Stock Mesa 6L6GC tubes. Pushing an EV speaker in the combo and life is good.

 

[Dreamtheaterrules]

That might explain why I didn't like the new Mesa AT7 in the big Mark V nearly as well as the old Mullard AT7 in the V25! Nowhere near the change in tone that I heard when I dropped the Mullard in the V25. Guess I got to track down some more NOS AT7s. 8)

 

[Markageddon]

Maybe the difference in the v25 naturally on channel 3 enabled the awesome sounds that can still be dialled with the Mesa variant. I favour M shapes on the graphic and loads of mids and low. Sounds and feels brilliant.

I really should spend more time with the 90w.

 

[Dreamtheaterrules]

That's really interesting because I haven't tried it yet since the AT7, but I found some great tones in the past with the W curve on C3. Your going the opposite way. I've never even tried that.

 

[Markageddon]

Sounds huge and smooth and sits well in the mix that way.
On your own play sounds demonic with the middle slider off, but just above the line, and anywhere up to half way between the bottom and middle line adds the crunch in a mix.. more or less full on 80hz, with all those huge smooth mids and its killer.

 

[BoogieHog]

Did anyone else lose their EFX Loop when they changed the V6 to an AT7?

 

[Wayno]

Did anyone else lose their EFX Loop when they changed the V6 to an AT7?

I didn't, i didn't get the hum that some have spoken of either. Which AT7 did you use? Jan/Philips? Jan/GE? any other NOS or a new production tube?

 

[Markageddon]

No FX loop loss here.
And from consensus that definitely doesn't sound normal.

 

[BoogieHog]

It's the Jan GE and it came back for a few minutes and now, it's gone again.
I put the Mesa 12AX7 back in and it's still not working :x

 

[bandit2013]

That may be a footswitch cable issue. Try using the rotary knob on the rear panel.

 

[BoogieHog]

That may be a footswitch cable issue. Try using the rotary knob on the rear panel.

I thought that too, Still nothing.

When it was working everything sounded really good and then, the volume increased (not "FX Bypass" loud but, louder) and no more EFX. I don't get it and I don't know what else to do. I plugged in my JP-2C and the FX worked so I know the cables and pedals are good.

 

[jaitrum]

Hi, I bought this 12AT7:
https://www.thomann.de/es/mesa_boogie_12at7.htm

Could I I change it in my Mark V:25 to get the staruation mod, or I have to buy a JAN, like this?

http://www.granada-audio.com/index.php?route=product/product&path=151_128&product_id=343


Thank you, is my first mod to my lovely amp, and I have some fear to open my precious mark5:25 and ruin my tone!

 

[Markageddon]

Yep. It works really well on the V:25. You need to put it in V2 position for that.
Never looked back after I did mine. Huge tone, dialled with higher than usual preamp dial settings that are allowable after the swap..

 

[bandit2013]

That may be a footswitch cable issue. Try using the rotary knob on the rear panel.

I thought that too, Still nothing.

When it was working everything sounded really good and then, the volume increased (not "FX Bypass" loud but, louder) and no more EFX. I don't get it and I don't know what else to do. I plugged in my JP-2C and the FX worked so I know the cables and pedals are good.

Check two things, the setting on the send level and verify the cable is fully inserted into the return jack. The return jack is a switch type jack. Try just plugging a cable into the return and then turn on the effects loop by footswitch or rear panel control. If you get no sound the FX loop is working. Follow that with just a single pedal and see if you get something.

If the 12AT7 caused an issue you would not have any signal when the FX loop is in the active state. It could be the logic controller. Try disconnecting the footswitch control, rotate both FX and channel select knobs a few times but slowly and return it to a desired position (do it with the amp on). I had an issue with the amp a few years ago and could not switch channels (it was stuck in default but cycling the channel select knob helped to free whatever was causing the issue). Just an idea.... Hope you get resolve on it. I doubt it is tube related if the only issue is not having the fX loop engaging. It could be the switched jack on the return or logic controller hanging up.

 

[BoogieHog]

That may be a footswitch cable issue. Try using the rotary knob on the rear panel.

I thought that too, Still nothing.

When it was working everything sounded really good and then, the volume increased (not "FX Bypass" loud but, louder) and no more EFX. I don't get it and I don't know what else to do. I plugged in my JP-2C and the FX worked so I know the cables and pedals are good.

Check two things, the setting on the send level and verify the cable is fully inserted into the return jack. The return jack is a switch type jack. Try just plugging a cable into the return and then turn on the effects loop by footswitch or rear panel control. If you get no sound the FX loop is working. Follow that with just a single pedal and see if you get something.

If the 12AT7 caused an issue you would not have any signal when the FX loop is in the active state. It could be the logic controller. Try disconnecting the footswitch control, rotate both FX and channel select knobs a few times but slowly and return it to a desired position (do it with the amp on). I had an issue with the amp a few years ago and could not switch channels (it was stuck in default but cycling the channel select knob helped to free whatever was causing the issue). Just an idea.... Hope you get resolve on it. I doubt it is tube related if the only issue is not having the fX loop engaging. It could be the switched jack on the return or logic controller hanging up.

Thank you Bandit! I changed the control to FX on all the time and it worked just fine. So, I need my FX button on my pedal fixed.

I appreciate everyone's input it really helped. I was freaking out.