MARK III PREAMP TUBE ARRAYS??

[Mark III Man]

Hey you Mark III heads, a question/querry on preamp tubes:

I first did a search (as not to ask redundant questions) and found some info on this to take note of.. It seems there are some mixed results with preamp tube swaps in the Mark III amps.

I have had other amps that 'voiced-up' radically different and those amps that didn't while swapping pre-tubes to dial-in my sounds. I don't know how the Mark III amps behave in this area.

I have a 'green stripe' '89 Simul combo that has a full set of ratty-looking, but still functioning, Chinese 12AX7 no-names... There's no marks or lettering on these at all, so I don't know if they are Mesa OEM or if some schlub stuck 'em in there in the past 20 years...

The amp sounds pretty good despite the Chi-Com AX7s and usually my motto is, if it ain't broke, don't fix it. My experience with these type tubes is that they are "servicable" and work OK, but can be a little bright, have a 'hard' voice and are usually thought to be generic-sounding.

If anyone has had good results with changing out the V1 slot and maybe the PI tube, I'd like to hear what you have done. I read a few posts where the V1, 2 and PI slots were changed to 12AT7, but I don't really want to reduce the R1 gain and would really like to chunk it up a bit with a more fat-sounding pre tube as long as I don't get a microphonic symptom when I switch to R2 or Lead modes..

To me, the R2 and Lead are pretty much there-sounding, but I'd like to fatten-up that R1 with more low end and mids if I can do so. I don't think the Chinese AX7s are helping R1 in this regard. I have always found them to be a so-so 'clean' channel preamp tube...

Any ideas from the Mark III heads out there??

Thanks,

Brian

 

[MrMarkIII]

Those no-label Chinese are most definitely maybe probably OEM. That's what my '89 combo came with new.
I personally like NOS Mullards, particularly in V1 (affects all modes), and V3 (lead mode). To my ear they are a bit less harsh on the top end and have a sweeter midrange. I don't really think they gave more/better bottom end but less treble sometimes can be perceived as more bass, especially when playing loud.
I've tried the 5751 (30% less gain) and 12AT7 (40% less), and went back to 12AX7s because I just like that bit of extra zing. The 5751 gave me a nice "woody" sound that's worth experimenting with, though. Different strokes.
If you can get your hands on the no-longer-available STR-454 power tubes (6L6), they are substantially better than the current 440s, and get the STR-450 EL-34s if you can afford 'em. Sometimes they show up used on eBay and elsewhere.
Mark IIIs rool.

 

[rvschulz]

i have found a couple of different options for altering the voice of my Mark IIIs ... First, you could contact Doug @ Doug's tubes - they have a "Mesa" setup that is very nice with a range of 12AX7s ... I use this for V3, V4, and the PI. It sounds nice with V1 & V2 - but ... the second option is ..

I have found a couple of OLD RCA and Mullards ... these are 50s or early 60s ... I put these in V1 & V2. Some love the Telefunken ... I know guys who GAS over tubes as bad as guitars or amps - it can REALLY become obsessive.

Once I found what i liked, which was replacing the old Chinese 12AX7 you currently have, I stayed there. I have a backup for a couple of them. I never put 12AT7 or anything else in a 12AX7 spot - I want all the gain of the design and let the tube function dictate the voicing - some tubes are a lot more "musical" than others. Unfortunately, you may need to tube trade to fine tune it.

Another voicing issue is your power tubes - we all know 6L6 sound a little different than the EL34. Most Mark III say EL34 in the outside sockets, 6L6 in the inners. I run all 6L6 - I called and spoke to Mike D about it. He said OK. He answered the **** phone too ... like, calling the Fender plant and having Leo answer it (if he could ... ).

Good luck.

 

[Mark III Man]

Those no-label Chinese are most definitely maybe probably OEM. That's what my '89 combo came with new.
I personally like NOS Mullards, particularly in V1 (affects all modes), and V3 (lead mode). To my ear they are a bit less harsh on the top end and have a sweeter midrange. I don't really think they gave more/better bottom end but less treble sometimes can be perceived as more bass, especially when playing loud.
I've tried the 5751 (30% less gain) and 12AT7 (40% less), and went back to 12AX7s because I just like that bit of extra zing. The 5751 gave me a nice "woody" sound that's worth experimenting with, though. Different strokes.
If you can get your hands on the no-longer-available STR-454 power tubes (6L6), they are substantially better than the current 440s, and get the STR-450 EL-34s if you can afford 'em. Sometimes they show up used on eBay and elsewhere.
Mark IIIs rool.

Hi and thanks, Mr MK III, for the info on the pre AND pwr tubes! I will try a Mullard/Valvo or = when I can get a few, as they are pricey and sometimes have a lot of hours on them even when sold as "new". The pwr tubes were a ratty set of STR-440 EL34 and some awful-looking Chinese generic 6L6GCs with bottom-getters..... I pulled them all and installed a pair of JJ KT77s in the outer sockets and a pair of Sovtek 5881s in the inners... It sounds better, but I think better 6L6s would improve it overall.

I think the Mullard (or =) would help the R1 channel to sound a little fatter as well - they do that in nearly all the amps I have tried them in. And yes, the little MK III combo rules lately, even when I have been gigging. I find using my EQ pedal thru the FX loop as a power-section/solo boost and my guitar's vol pot works extremely well. My MI Audio Tube Zone really zings in the R1 channel and makes it sound like a cranked Twin - think "Fortunate Son" crunch tone.

I have been using my 50 watt Marshall (Mark C. Low Gain "Jose" modded) with a wet/dry/processor to pwr amp set up for a while and now really love the MK III tones. I really have always been a "Marshall-Guy" and am so stoked I tried the Mark III again. Last night, even in the Class A power mode, 1 1/2 on the Master was blasting loud! My band mates freaked when I showed up with the little short combo after seeing the big rig at all the shows.... Ha ha ha!

 

[Mark III Man]

i have found a couple of different options for altering the voice of my Mark IIIs ... First, you could contact Doug @ Doug's tubes - they have a "Mesa" setup that is very nice with a range of 12AX7s ... I use this for V3, V4, and the PI. It sounds nice with V1 & V2 - but ... the second option is ..

I have found a couple of OLD RCA and Mullards ... these are 50s or early 60s ... I put these in V1 & V2. Some love the Telefunken ... I know guys who GAS over tubes as bad as guitars or amps - it can REALLY become obsessive.

Once I found what i liked, which was replacing the old Chinese 12AX7 you currently have, I stayed there. I have a backup for a couple of them. I never put 12AT7 or anything else in a 12AX7 spot - I want all the gain of the design and let the tube function dictate the voicing - some tubes are a lot more "musical" than others. Unfortunately, you may need to tube trade to fine tune it.

Another voicing issue is your power tubes - we all know 6L6 sound a little different than the EL34. Most Mark III say EL34 in the outside sockets, 6L6 in the inners. I run all 6L6 - I called and spoke to Mike D about it. He said OK. He answered the **** phone too ... like, calling the Fender plant and having Leo answer it (if he could ... ).

Good luck.

Hi and thanks, MK III, I'll contact Doug for more info. I have an old Telefunken, some old black plate Raytheon, Sylvania, etc., that I'll try as well. I have been known to GAS wayyyy too much over tubes as well and sometimes with little real result! You know some guys swear by the Chinese 12AX7s for the high gain stuff, but to me, they can be harsh and fuzzy/buzzy... Same with Sovtek 12AX7WA and WBs.... I think if you like a more "modern" voicing, the 12AX7s are great.... I like a fatter, less fuzzy tone with not all the mids scooped out!

I agree with you on not swapping to a lower gain preamp tube like a 5751, 12AT7, etc.... I find it governs the preamp circuit too much. They are designed for the 12AX7 gain structure.... And, I don't dime my gain (7 or so) and my lead gain is at 6, so lower gain tubes are not the issue. I'd rather have a great amp tone that's a tad clean, but barky, and then hit it with a boost pedal or dig in while playing.

I do like the EL34s in the outer sockets, so I'll stick with those. I like the way EL34s break up and mixed with the 6L6s, it's really a sweet combo. And I have also had the pleasure of speaking to Mike B. right away while calling Mesa/Boogie. He actually LIKES to chit chat and if he senses you're really interested in his craft (I think especially the older stuff), he's so damned helpful and patient!

Brian

 

[daveg62]

Yeah Doug recommended a set for my Mark III and I've been a happy camper ever since. Been awhile so I can't even remember what they were. I remember it was a mixed bag though. Contact him, he's the expert.

 

[Mark III Man]

Yeah Doug recommended a set for my Mark III and I've been a happy camper ever since. Been awhile so I can't even remember what they were. I remember it was a mixed bag though. Contact him, he's the expert.

Hi Dave, any chance you could check to see what the MK III array he sent you was? If it's a hassle, no sweat, I just wanted to get an idea of what worked for you, etc.... It's a hassle to get to that friggin' V-1 tube! LOL!

Do you think the quality of the rev driver tube is a big issue?

What power tubes do you have for your rig? Do you run EL34/6L6GC? ****, I sound like a detective with all the questions!

Thanks,

Brian

 

[boogiemon]

i bought a MIII off ebay & thought it was ok until i put tung-sol's in v1-v3, now it sounds fantastic to my ears. i think v4 & v5 are the reverb driver & phase inverter tubes so v1-3 will be your primary preamp tone shapers. The tung-sols are about $12-$15 each but well worth it for the MIII: almost as much gain as the chinese tubes but way more musical.

g'luck.

Hey you Mark III heads, a question/querry on preamp tubes:

I first did a search (as not to ask redundant questions) and found some info on this to take note of.. It seems there are some mixed results with preamp tube swaps in the Mark III amps.

I have had other amps that 'voiced-up' radically different and those amps that didn't while swapping pre-tubes to dial-in my sounds. I don't know how the Mark III amps behave in this area.

I have a 'green stripe' '89 Simul combo that has a full set of ratty-looking, but still functioning, Chinese 12AX7 no-names... There's no marks or lettering on these at all, so I don't know if they are Mesa OEM or if some schlub stuck 'em in there in the past 20 years...

The amp sounds pretty good despite the Chi-Com AX7s and usually my motto is, if it ain't broke, don't fix it. My experience with these type tubes is that they are "servicable" and work OK, but can be a little bright, have a 'hard' voice and are usually thought to be generic-sounding.

If anyone has had good results with changing out the V1 slot and maybe the PI tube, I'd like to hear what you have done. I read a few posts where the V1, 2 and PI slots were changed to 12AT7, but I don't really want to reduce the R1 gain and would really like to chunk it up a bit with a more fat-sounding pre tube as long as I don't get a microphonic symptom when I switch to R2 or Lead modes..

To me, the R2 and Lead are pretty much there-sounding, but I'd like to fatten-up that R1 with more low end and mids if I can do so. I don't think the Chinese AX7s are helping R1 in this regard. I have always found them to be a so-so 'clean' channel preamp tube...

Any ideas from the Mark III heads out there??

Thanks,

Brian

 

[daveg62]

Hi Dave, any chance you could check to see what the MK III array he sent you was? If it's a hassle, no sweat, I just wanted to get an idea of what worked for you, etc.... It's a hassle to get to that friggin' V-1 tube! LOL!

Do you think the quality of the rev driver tube is a big issue?

What power tubes do you have for your rig? Do you run EL34/6L6GC? sh!t, I sound like a detective with all the questions!

Thanks,

Brian

Yeah I will check it out later today when i get home from work, I'm curious myself. I run EL34's in the outer sockets, and always run in Class A. I prefer the sound of the EL34's in this amp. I know they are EL34 Ruby's from Doug.
I personally don't use the reverb on this amp, I run a G major in the loop and it has nice reverbs and delays.

 

[CoG]

Dunno if anyone's still interested but two things:

1. PHASE INVERTER. ****, the PI tube makes a big difference in the Mark III. I personally really like NOS Mullard 4024s in there, they ae NOT expensive and really improve the clean tones.

2. If you have had the reverb mod done, you kind of need to be careful about picking your reverb tube because it's pretty "audible." when you kick in the reverb. I have a 4024 in there in my green stripe and when the reverb kicks in it's a warmer, rounder tone-- note that if you're trying to do modern metal riffing, you may not want this.

 

[Mark III Man]

Dunno if anyone's still interested but two things:

1. PHASE INVERTER. ****, the PI tube makes a big difference in the Mark III. I personally really like NOS Mullard 4024s in there, they ae NOT expensive and really improve the clean tones.

2. If you have had the reverb mod done, you kind of need to be careful about picking your reverb tube because it's pretty "audible." when you kick in the reverb. I have a 4024 in there in my green stripe and when the reverb kicks in it's a warmer, rounder tone-- note that if you're trying to do modern metal riffing, you may not want this.

Hi, is it cool to install a 4024 PI tube in there where the 12AX7 is speced? And what reverb mod are you referring to? A Mesa/Mike B. mod? Sounds cool!

Brian

 

[Mark III Man]

Hi Dave, any chance you could check to see what the MK III array he sent you was? If it's a hassle, no sweat, I just wanted to get an idea of what worked for you, etc.... It's a hassle to get to that friggin' V-1 tube! LOL!

Do you think the quality of the rev driver tube is a big issue?

What power tubes do you have for your rig? Do you run EL34/6L6GC? sh!t, I sound like a detective with all the questions!

Thanks,

Brian

Yeah I will check it out later today when i get home from work, I'm curious myself. I run EL34's in the outer sockets, and always run in Class A. I prefer the sound of the EL34's in this amp. I know they are EL34 Ruby's from Doug.
I personally don't use the reverb on this amp, I run a G major in the loop and it has nice reverbs and delays.

Thanks, I'm curious too! I also do like the Class A/EL34 setting a lot. What's the make on the Ruby-branded EL-34's you got from Doug's Tubes??

Brian

 

[CoG]

Dunno if anyone's still interested but two things:

1. PHASE INVERTER. ****, the PI tube makes a big difference in the Mark III. I personally really like NOS Mullard 4024s in there, they ae NOT expensive and really improve the clean tones.

2. If you have had the reverb mod done, you kind of need to be careful about picking your reverb tube because it's pretty "audible." when you kick in the reverb. I have a 4024 in there in my green stripe and when the reverb kicks in it's a warmer, rounder tone-- note that if you're trying to do modern metal riffing, you may not want this.

Hi, is it cool to install a 4024 PI tube in there where the 12AX7 is speced? And what reverb mod are you referring to? A Mesa/Mike B. mod? Sounds cool!

Brian

Yeah, 12AT7/4024s will sub in for 12AX7s just fine.

The reverb mod is just replacing one resistor, anybody with some experience can do it. It makes the reverb louder both when its on and off. It doesn't make the reverb any *better*, just more, and it's still not a whole lot of 'verb. I only have it on one of my MkIIIs and I'm not gonna bother doing it on the other.