Considering some alternate 12ax7 tubes...

[bandit2013]

I have almost tied all of the current production 12ax7's, except for a few.

Tung Sol: not bad at all, works the best in a Mark IV (complete).

EH12ax7: seem a little hotter than the TS in tone, not as deep or warm. tends to enhance heater noise if used in an AC heated circuit. Does not work well in V3-V6 positions in a Mark V due to the hum issue.

Penta Labs Chinese (look like Sino tubes): Had only three to mess with, did not get good results due to microphonic issues.

Mullard reissue: okay, but too much compression for gain channels. They work great as a PI tube but not really good for guitar amp gain stage.

Sovtek LPS: Similar to Mullard but again, best suited for PI as the long plates and overall design lead to mechanical noise transfer. Mullard also exhibits this trait. May consider other Sovtek flavors but not impressed.

Mesa or JJ : The Mesa branded JJ tube is not as noisy as the JJ braned tube. Both generate abundant amount of white noise (hiss). They seem to perform better in an RA100 than a Mark V. With the original Mesa tubes in my Mark V, tone is on the brittle side and not really enjoyable.

What next: I am trying to avoid the duds (with tubes that is hard to do). I am considering a Gold Lion B759, but if it is anything like Mullard or the Sovtek LPS it will not do well in a Mark V as the primary. I may just get one to try it. I am also considering the Preferred series 7025 from "the Tube Store". They look like the same tube from TAD, Northern Electric and are probably Ruby tubes since I have one of those and structure looks identical.

As it seems, if I tune the amp to get the best sound out of CH2 crunch mode, the other two channels suffer. If I go the other way, say tune to get the best tone and character out of CH3, CH2 crunch mode gets muddy (abundant bass).

Anyone have experience with the Gold Lion B759 (12ax7)?

 

[jnoel64]

Bandit, have you seen/read this?
http://www.thetubestore.com/12AX7-Tube-Review

Oddly enough, the Svetlana 12AX7 got good reviews. I've been hung up on Tung-Sols in my Dyne, but am considering trying some Svetlanas next time around.

 

[dodger916]

Have you guys tried any vintage tubes? In my experience, much of what's being produced today falls short of the old stuff.

 

[Markedman]

I bought a closet queen 1960's danelectro dm 25 for $200 with 3 amperex bugle boy 12ax7 tubes in it. Trying them out tonight in my Mark lll. Sold the amp for $300.

 

[dodger916]

I bought a closet queen 1960's danelectro dm 25 for $200 with 3 amperex bugle boy 12ax7 tubes in it. Trying them out tonight in my Mark lll. Sold the amp for $300.

Amperex Herleen, Holland-made tubes are among my favorites. Here's a somewhat encyclopedic thread from the "good ol' days" detailing the characterisitics of vintage tubes:

http://forum.grailtone.com/viewtopic.php?t=749&highlight=timbre+wolf

 

[bandit2013]

Bandit, have you seen/read this?
http://www.thetubestore.com/12AX7-Tube-Review

Oddly enough, the Svetlana 12AX7 got good reviews. I've been hung up on Tung-Sols in my Dyne, but am considering trying some Svetlanas next time around.

Yes, I have read that, also others on the Svetlana. Some like them some do not.

It all depends on what amp they go in. Mark IV is not very picky and seems to work well with almost any tube I put into it.
RA100 also follows similar traits as the Mark IV. My primary focus is the Mark V. Seems to be a very sensitive to some tubes and great with others. So far the only tube I have liked in the Mark V are the tubes I bought in the 90's which were Mesa Chinese tubes. If I can find a similar in tone and character I will be happy, so far that has not happened.

 

[swbo101]

This is what I've been using (Mark IV(a)) and have been happy with:

V1 - Tung-Sol (RI)
V2 - JJ
V3 - JJ
V4 - Stock Mesa
V5 - Mullard (RI)

 

[bandit2013]

I have decided to get the Gold Lion 12ax7/b759 tube just for kicks. Hopefully it will not be a disappointment. Along with that, I bought 5 of the new Mullard short plate 12ax7/cv4004. They look similar to the TS/EH but why not give them a shot too. I did consider the Svetlana version. The long plate Mullard re-issue is okay but noisy. I still prefer the Sovtek LPS in the PI spot. The Mullard long plate 12ax7 sounds close. Compared the Sovtek LPS to the Mullard re-issue in V1 on a few different amps, not much of a difference. Both seem to transfer mechanical vibration into the signal. I can live with a little tube rattle noise from the power tubes, but when it makes it into the signal path and finally heard from the speaker is not desirable. I expect the new Mullard CV4004 will sound similar to the Tung Sol 12ax7 or EH12ax7. I guess I will find out when they arrive. I am planning on using them in place of the Mesa 12ax7-a Chinese square getter tubes. Those actually sound the best in any amp I have put them into. Most of what I have in that tube is near the end of its useful life.

 

[Markedman]

I must say the Amperex bugle boy 12ax7's really opened up the tone of my Mark lll. I put them in V1 and V3 and the difference was immediately noticeable, especially the high end. I liked the Mesa SPAX best out of the dozen or so different tubes I tried, I could control feedback well with the SPAX and there was no harmonic feedback at loud volumes, but they were very dark sounding. These bugle boys not only give me more clarity and volume, but the attack is much crispier and open without compression, kinda like taking a pillow off the speakers. I definitely have the "most bestest" tone ever in my life, but I'd trade it all for just a little bit more!

 

[dodger916]

I must say the Amperex bugle boy 12ax7's really opened up the tone of my Mark lll. I put them in V1 and V3 and the difference was immediately noticeable, especially the high end. I liked the Mesa SPAX best out of the dozen or so different tubes I tried, I could control feedback well with the SPAX and there was no harmonic feedback at loud volumes, but they were very dark sounding. These bugle boys not only give me more clarity and volume, but the attack is much crispier and open without compression, kinda like taking a pillow off the speakers. I definitely have the "most bestest" tone ever in my life, but I'd trade it all for just a little bit more!

In my experience, new tubes just can't beat good vintage ones, especially in the older amps.

 

[Chadd]

My Roadster is really picky about what goes into V3 and V5, it did not like my old Sovteks or the EH.

 

[bandit2013]

If I had the cash flow to re-tube with all NOS I would do so. I may just do that and re-tube the Mark V with Vintage tubes but trying to figure out what tubes to use is the hard part and can be expensive if they turn out to be duds or sound terrible.

I now have 5 tube amps. What am I thinking?

Actually, trying to find a current production tube that will last as long as they used too may be too much to ask. However, it is all about tonal quality. Mark IV does not seem to matter all that much. TS all the way sounds great. Of course I am no longer using the MC90 in the combo since it gave up the voice coil.

The Mark V is the sensitive amp that I have. I am hoping the short box plate Mullards sound better than its cousins (TS, EH, and now Svetlana). I guess I will see when the tubes arrive. The Second amp that requires 7 preamp tubes is the RA but that does not seem to be as sensitive. Actually that one sounds sic with what is in there now, the only NOS tube I have in there is an RFT 12AT7 since it was reasonable in cost. I was almost considering getting a Marshall but I am getting some great tones from the RA100 straight up with no effects. No need for another tube amp, but I will not make any promises.

 

[bandit2013]

As I have tried to tube roll the Mark IV (B version). The best sound preamp tubes for that amp is all Tung Sol with the exception of the PI tube which is a match triode Sovtek LPS.

I did get the Gold Lion B759 12ax7 and 5 of the new Mullard CV4004. I do like the Mullard short plate CV4004 in the Mark V. I am using them in the V3, V5, V6 positions. I tried one in the V4 (reverb driver) but prior to this, the reverb circuit died. It was not tube related either. M2 (J175) which is a JFET was not turning off and it pulled the grid to near ground (89 ohms). I suspect the relay that switches CH1+2 (150K) and CH3 (220k) were not being taken to ground to form a voltage divider to the grid. I removed M2 and the reverb now works again, but over the top. I soldered a 220K resistor on the Drain and Source pads on the circuit board. Still a bit too much reverb. However, I was able to correct the abundance of reverb with a 12AT7 that I replaced in my RA100. The lower gain increased the CH3 definition and eliminates the muddiness. The resistor fix is temporary. I will have to get a J175 (probably will buy a few, I may even have some at work).

The Mullard Long plates (termed the reissue tube) I was not fond of. However, the two that worked well in a non driver circuit (phase inverter, reverb driver, latter gain stages of CH3) actually sound amazing in V1 and V2. With the fix to the reverb circuit (not intentional) with the lower gain 12AT7, the amp never sounded better. I was concerned that I would not be able to switch off the reverb, yep that still works. A change in the 10k resistor that is on the power tube board that feeds the reverb transformer would be best if it was 22k ohms. At leas the 12AT7 is a 30% drop in gain so that helps. Also this tube position was the culprit of the power supply hum. Drop in gain eliminated it.

The Mullard CV4004, it falls between the Tung Sol 12ax7 and EH12ax7. It is not harsh or too deep. Probably the same tube as the Svetlana 12ax7. Mica spacers are identical to the EH tube, the box plate is also the same as used in the EH and TS tubes. The ruby tube I have is quite similar in some respects. I admit to not liking the long plate Mullard but after installing the CV4004, the Long plate mallard in V1 and V2 sound great.

As for the expensive tube: complete dud in the Mark V. I tried it in V1, sounded excellent for a short time. While I was still tube rolling, it started to make static noise. If it was not for the static issue, it would still be in my amp. What a disappointment. However, I decided to give it another chance and tried it in V4 in the RA100. Sounded really good in the clean channel primary. No static. Must be related to the operating voltages of the Mark V. The tube sounded great when only using Ch1 but in CH2 or CH3 it was noisy like a poor AM radio in a lightning storm. As for use in the RA100, it brings out too much bass. The Hi/Lo channel is way to bright so I tried it there for kicks, it got even brighter. The Mullard long plate sounded better in a high gain channel as the primary. I tried the CV4004 with the same results as the B759 GL. They will enhance the full spectrum and bring out deep and bright tones. They saturate very nice. V1 =CV4004 and V2 = Tung Sol sounded awesome in the RA100 with -3dB power soak. My goal is to darken the Lo channel and enhance the Hi channel. The Mullard LP did the best overall job. At least I can reach all of the preamp tubes in the RA100 without having to put my hands in awkward positions to reach V1 as is the case with the Mark V. I know, cut out the front panel, considering it. but have not done so. I will have to give the Gold Lion B759 a try in the Mark IV. In short, not worth the money. It is a nice tube and sound great if the tube is not biased with a high gain factor like it is with the Mark V. CH3 raises the bar on the supply voltage and begins to boil off the cathode. Perhaps it need a burn in time. I did not like the Long Plate Mullards one bit, but since I have used them as PI tubes for a little bit, they sound much better. I have one that pings every time I change channels so that one remains as a PI tube.

Today, I decided to get some more Long Plate Mullards. Figured I would also take a chance on one of the Northern Electric tubes. (Yes it probably is Chinese, same MFG as the tube doctor, probably a ruby tube, also the Preferred Series 7025 from the tube store looks to be the same. I ordered a few of those too. Also had to get some more 12AT7. I am not done with those. This time I ordered JAN/Phillips, although the RFT is working great in the RA100. I will have to experiment by pulling the tube and see if the amp still makes a sound. Not sure the tube is disabled when the effects loop is not used.

Bummer about breaking the Mark V... Not sure what really happened there. If you thing your reverb has too much presence in the sound, drop the gain with a 12at7 (if original used 12ax7). There will be a side effect on CH3, but it is not a bad side effect at all. It is similar to using a 5751 in V1 but only better.

 

[bandit2013]

The following will be a long winded review of the various tubes I have experimented with.

Here is the list of tubes:
Tung Sol 12AX7 (includes the gold series as well, not much difference)
Electro Harmonix (EH) 12AX7
Mullard re-issue (Long Plate)
Mullard CV4004/12AX7
Gold Lion B759/12AX7
Preferred Seires 7025 (the tube store)
Northern Electric 12AX7

I will have to make several posts as it is long and to break things up.

 

[bandit2013]

I have spent nearly a week tube rolling various mixes of most of the available 12ax7 tubes. There are those I did not try simply because I have versions with other brand names on them. Sovtek for instance has many different models of the 12ax7 tube that I did not bother with, not because of familiarity but due to too many to try. Just to boil down the attempt to find the holy grail or really awesome tube combination, it did not take long to find out that what works extremely well for the Mark V does not in the RA100. Similar results were discovered with the Mark IV. Key point about preamp tubes, some will have different gain levels but what is most important is the frequency response curves which are never published or shared. There is little hope since there is a simple chart (needs to be updated) on tube characteristics in terms of L,M,H. What is miss leading, the weighed numbers 1-10 are based on overall peaks within a specific band-width. The tube may have higher or lower gain than the typical 100. The chart does not indicate gain of the tubes. So if a tube rates all 10’s it may have a relatively low gain in relation to one that has lower weighted numbers. Also pay attention to noise (mostly rated as mechanical noise and not electrical noise).
For starters (and probably stated before): I have a Mark V head, SED =C= 6L6GC, EH 5U4G and driving a Mesa Recto cabinet which was overhauled with EVM12L Black Label speakers. The RA100 head, SED =C= EL34 and driving the old V30’s that were removed from the Recto cab and are installed in a traditional sized slanted 412. The Mark IV combo, Svetlana 6L6GC (New Sensor version and not SED), modified to fit a Fane Studio 12L (similar in tone to an EVM12L Classic) also driving in parallel an Eminence Tonker Light mounted in a 2/3 open back deep 1x12 cabinet. On occasion I will run the Mark IV through the EV speakers in the cabinet used by the Mark V. All of my amps us a Sovtek LPS match triode for the PI. On rare occasion I may use a JAN/GE 5751 as a PI for more headroom. Type of music I play crosses many boundaries from blues, jazz, heavy metal, classic rock (60-80), and it is always fun to crank it up into grunge territory to what ever they call it these days. I am by no means an expert (one who has a mental library of songs) but rather one who enjoys doing my own thing. Of course there are the influences from Pink Floyd, Scorpions, Judas Priest, Led Zepplin just to name a few.
Tung Sol: 12AX7: (manufactured by Reflektor / New Sensor) Most of you are familiar with this tube. Not much else to say but they are really great tubes. If you are not that familiar, or have not yet experimented with this tube, it is one of the better offerings as a current production 12AX7. Depending on what amp it is used in, it can be amazing or too deep. I have normally used a TS12AX7 in the front end of the Mark V. I had tried stuffing this tube in all positions (except for the PI). The Mark V tends to be on the bright side especially in CH3. The TS did seem to roll off a little of the top end and enhance some girth on the bottom. This is my favorite tube for the Mark IV (in all 5 positions). Clean is crisp and dry (more of an acoustic sound than a vintage fender with a slight bit of edge). As for the Lead (never really use rhythm channel 2 unless I am running though a 412 cabinet) nice sinister tones and grit to satisfy the darkest grinder out there. I have tried this tube in the RA100, it worked best in V1 and V2 but for the clean channel (V4 and V5) it dropped bottom and this channel needs to be picked up in the high end which is quite the opposite to the Vintage Hi/Lo channel.

EH 12AX7: (manufactured by Reflektor / New Sensor ), Like the TS above, I am sure many of you are familiar with this tube as well. I originally bought these for the Mark IV as replacements for the 14year old Mesa (JJ) tubes that I never got around to replacing until 2012, Along with the Original STR420 which are great tubes if you can find them. EH appears to have more gain than the TS. All of the boxes and tubes were marked with gain per triode. Most of them were 115-125. What it boils down to is how it sounds. Not as deep as the Tung Sol. A bit more brighter and not as bold. The Mark V performs well with the EH tube in selected positions. I did favor this tube in V1, V5-V6. It is not bad for V2 and V3 but based on my likes and dislikes, I preferred something else. As of now, I am not using the EH tubes as they are on reserve in case I am in a pinch. I have rolled them into the RA100 and they did well in the clean channel (V4 and V5). Vintage channel was still too bright. I have no complaints about these tubes. Over time I have simply rolled them out for something different. If I needed to brighten up an amp this would be my choice but there are better out there.

 

[bandit2013]

page 2 - continued

Mullard Reissue (LP) 12AX7: (manufactured by Reflektor/New Sensor). At first I did not like these tubes. They seemed a bit mechanically noisy. One out of three would ping when I changed channels in the Mark V. I put them on PI duty for a while and after getting some burn in time as a current driver they really improved (not that it was required). I gave them another chance. Actually love these tubes in V2 and V3 of the Mark V. Cruch mode is incredible on CH2. I have also used one as the primary (V1) with great results. I almost believed I was done rolling the Mark V but there are more to discover. Currently I still have the Mullard re-issue LP in V2 and V3. This tube will thicken up the distortion without too much compression as long as it is not in V1. I have used it in V1, sounded great. This tube in V1-V3 and leave the rest as Mesa 12AX7 has a great sound. As for the RA100, tried many different combinations of this tube with some mixed results. All you need is one of these in V2 of the RA100 to give it more of a grinding bite that is comparable to Mark IV mode of the Mark V when using the Vintage Hi (technically the Hi/Lo channel is just named Hi/Lo and not vintage anything, but many have referenced it as vintage who also must have or did have a Rectifier amp). In Lo setting, the tone is still there but with slight roll off on the top end. I did not try this in the Mark IV except for the PI position. In close inspection, this tube is similar to the Sovetek LPS. There are differences in tone when used at or near the front end. The Sovtek was a bit thin sounding in comparison.
Mullard CV4004/12AX7: (manufactured by Reflektor/New Sensor). This is the new release with the Mullard brand. Actually looks similar to the Sevetlana 12ax7. Construction has similarities to both TS and EH. Mica spacer is the same as it is on the EH tube. Same box plate. They look like identical tubes with a different brand name. They are not the same tube when it comes to how they sound. Definitely dynamos. I started rolling in these as soon as I got them. I only have 5 so doing a complete setup on the Mark V was not possible. However that being said, the winner of the V2 on all counts was the Mullard re-issue (LP). This little jem sounded great in V1, V3, V4-V6. They are definitely hot tubes. I think a bit too hot but not in a bad way. The gain is much higher than it is with the long plate version of the Mullard. When installed in V3, CH3 lost some definition with slight compression. Final resolve was keeping the CV4004 in V4-V6. Also helped the reverb I was having some issue with. Before I settled on this tube, I gave them a try in the RA100. As the story goes, they did not perform well with the clean channel at all (V4 and V5). It enhanced the darkness of the circuit which was contrary to my goal. In the Hi/Lo channel it sounded great with CV4004 in V1 and a TS in V2. That worked out great for a few days. Then I decided to play my strat type (Carvin Bolt C HSS, also have another on order but SSS). I love the RA100 for the expressive blues and classic rock and the strat type guitar sounds the best. Of course there is the CS6 (Carvin’s version of a Les Paul) which also is amazing through the RA100. So my primary guitar did not sound as good as I hoped it would with the CV4004. What works the best in the RA100: Mesa vintage 12ax7a (Chinese) in V1, Mullard LP in V2, NOS RFT 12AT7 in V3, Preferred Series 7025 (the tube store, more on this latter) in V6, and the best for the clean are the tubes I dislike the most in the Mark V, Mesa branded JJ tubes. However, there is yet one more tube that takes the cake in V4 but I only bought one to try it out and it has a home until it dies or fades out (Last tube on this long and tiresome novel).
Preferred Series 7025 (manufactured by Ruby, tested and selected by “the Tube Store”). This is a really good tube. I compared it to one of the Ruby HG tubes and it is nearly identical. I have tried it in all of the amps and found it to work the best in the reverb send circuit. Hum is virtually non-existent. Just one of these in V4 tamed the hum in the Mark V to nothing. (CV4004 also had similar effects). I rolled this tube into the Mark V but from V4-V6 so there is not much to comment about in the Mark V on the front end. Does not provide as much depth and top end grit as the CV4004 in the Mark V. It did improve definition when used in V4 on CH3 but I preferred the CV4004 instead. This was the winner in the reverb circuit of the RA100. That really made a difference as it also alters tone of the overall sound of both channels. As for the Mark IV, I was running out of options. Too much gain and the lead looses definition (fizzy), not enough well you, just weak. This tube is middle of the road and actually sounds great in the Mark V. In all positions it did bring down the Lead channel grunt a few degrees. However, change in V1 to a CV4004 and leaving the rest PS 7025 sounded better than the Tung Sols.

 

[bandit2013]

page 3 - continued (and the last of it)

The Dud:
Gold Lion B759/12AX7 (manufactured by Reflektor /New Sensor). This tube had promise, well on paper that is and in reviews. Perhaps it would be best suited in Phono players or high Fi audio. That is my comment, sounds more like a review on the Mullard re-issue. The primary (V1) of the Mark V was the original intent for buying this tube. It almost had the best response as well as the worse. I would have stopped my tube quest if it was not for one issue. The Mark V (as well as some ladder gain amps that only have one primary and cascaded gain stages) does bias voltage shifting depending on what channel you select. In clean channel, this tube sounded incredible. Not too shabby in CH2 either, but in CH3 and any instance of vibration (which will always be present) and the combination of the higher voltage bias on V1 to increase gain caused a chain of events reminiscent of last year’s 4th of July. No it did not catch fire or explode but sounded like it did, actually more like a noisy sparkler that just got louder and louder. Call it the crackle tube, not something I desire in an amplifier or in my tone. I only bought one considering the much higher than typical cost. The Gold Lion KT77s are tops but the B759 not. It sounded great, almost perfect until it went into saturation run away. I did attempt to use it in the RA100 after this event and it never happened again (unless I put it in the Mark V). In the RA100 it behaved quite well but against the grain of sanity. It made the clean channel much darker than any other tube I tried. The Mullard re-issue is a much better tube and far than half the cost. I even tried it in my Carvin V3MC (I was tube rolling that as well), sounded bland and the same for the Mark IV. This tube would be better served in Hi-Fi than a tube amp.

The Holy Grail:
Northern Electric 12AX7 (manufactured by ????, may be Chinese but it sure does not look like anything I have except for the RFT 12AT7 which shares similar plate style but yet different. If this turned out to be a dud, at least the box it came it was very impressive. Carton was made out of tin or steel with molded foam insert. This tube was fully protected or any miss-hap in handling or mail delivery. At this time, I was settled on the arrangement for the Mark V. I wanted to focus on the RA100 clean channel. Damn does this tube sound awesome. It sounded so good I was willing to pull the Mark V apart and give it a try. Swapped the Mullard Long Plate in V1, actually moved it to V3 and put the Mullard CV4004 in the Mark IV primary. This tube cost a little more than the Gold Lion B759. And guess what, it was worth every penny. The Mark V never sounded better. Clean channel in all modes was just what I wanted. All of my favorite guitars sounded great including my strat like guitar. It does not end there either, CH2 all modes are awesome (I was considering getting a DR or DR Roadster, now I feel that is uncessesary). The rest of the amp only gets better. CH3 is just where I want it. When I was all done, I removed all the preamp tubes (why?) to retest the bench mark Mesa tubes. Figured I have not used them in such a long time I forgot what the amp sounded like. Not bad. After that, in the same order they came out I installed each tube one at a time and gave it a try. Just the NE tube in V1 and the rest as Mesa (JJ tubes) sounded great. Change in V2 to the Mullard things were getting better. Mullard in V3 I could have stopped right there. The NE 12AX7 is the best 12AX7 (current production) tube I have ever had the pleasure of experiencing. I did not want to pull it from the Mark V. (no trial in the Mark IV, sorry). Now I need two more of these to complete the RA100. What I have in there is great for now but one of the NE tubes in V1 and V4 would be optimum. This tube is on my KEEP LIST.
Final result: Very Happy
Mark IV:
V1 = Mullard CV4004
V2,V3,V4 = Preferred Series 7025
V5 = Sovtek LPS
V6-V9 = Svetlana 6L6GC

RA100:
V1 = Mesa Vintage 12AX7A (until I get more NE tubes)
V2 = Mullard 12AX7 (LP)
V3 = NOS RFT 12AT7
V4,V5: Mesa 12AX7 (JJ tubes) this will also change.
V6: Preferred Series 7025
V7: Sovtek LPS
V8, V9, V10, V11 = SED =C= EL34

Mark V:
V1 = Northern Electric 12AX7
V2,V3 = Mullard 12AX7 (LP)
V4, V5, V6 = Mullard CV4004
V7 = Sovtek LPS
V8,V9, V10, V11 = SED =C= 6L6GC

 

[bandit2013]

Another lesson learned. Always helps to use the actual speakers you will be using when you tube roll. While I was working on the Mark IV, I had the chassis out sitting on top of the 412 cabinet. At about this time I was suffering hearing fatigue.

Once I got the chassis back into the combo and all hooked up. The Mullard CV4004 was a bit too much for the V1. Sounded good but the extension cabinet was practically jumping off the floor. Attack was way too prominent as well. (May need to change speakers in the extension cab). I decided to give the Gold Lion B759 another shot before going into the dust pile. No issues with static like I encountered with the Mark V. Actually the tone I am getting on the lead channel with the GL B759 and the PS7025 is quite similar to a traditional or iconic DR tone. So I will take back the Dud statement and make it only half a dud since it sounded quite good in the Mark IV considering the speakers in use, did not work well at all with the RA100 and just static in the Mark V. Actually did not sound that bad thought the 412 either but much better with the Combo speaker and the extension cab.

 

[bandit2013]

It did not take long. The Gold Lion B759 crapped out into a static generator. If it was not for the static issue it would be a nice tube. I should have bought more Northern Electric. I am not trying to promote tubes of any kind. If I was, it would be buy more SED =C=, but since I am selfish, don't buy any SED =C= so I can have them all to myself.

Final roll in the Mark IV Combo.
V1 = Mullard CV4004
V2,V3, V4 = Prefered 7025
V5 = Sovtek LPS
V6,V7, V8, V9 = TAD 6L6GC-STR ( I did not retire the Svetlanas just yet as they are still sounding really good).

It is hard to distinguish which tube CV4004 or the 7025 has higher gain, but I believe it would go the CV4004. With this tube on the front end and the 7025 everywhere else I was rolling brings out crystalline chime on the clean channel. The Tung Sol tubes I had used I put back in for comparison. The Tung Sol Gold pin was what I used in V1. Just a reminder if the Tung Sols were new, it would be a different story so they are very much used up and getting a bit on the flat side. Still the clean channel (Rhythm 1) was in peak performance, what suffered was the Rhythm 2, seemed a bit useless, Lead was deep and not bad. However, with latest roll, this amp sounds incredible. Clean (RH1) is much better and the bass is tight. The 7025 add to the tightness of the low end but yet not brittle on the high end. Similar to the Tung Sol but thinner in the midrange but not as thin or shallow as an EH12AX7. With the CV4004 at the front end, enhances the boldness of the Lead channel considerably and gives it more bite. Definition is comparable to the Mark V CH3 Extreme, also tone is similar to a DR Modern high gain. There was quite a different reaction with 7025 in V1 and CV4004 in V2. The Lead channel lost its definition and clarity. RH1 picked up more edge. RH2 sounded great but with the final roll, RH2 sounds more like the Lead channel did with the Tung Sols, and the Lead channel sounds more intense, bold and juicy and not too thick in the mud. The Mark IV sounds better now than it did when I fist bought it. The Mark IV has taken a step up in which amp to I pick first. Your own side effects of tube rolling may be different than what I have experimented with simply due to differences in speakers, guitars, how you set up the amp, and of course power tubes.

 

[bandit2013]

At this point I would not recommend jumping on my opinions and stocking up on any various tubes for your amp. I decided to revisit some combinations that I found effective with the Mark IV that I wanted to explore with the Mark V. (trick to long post, do it in word first).

Tube roll with the Mark V: In more detail.
I was satisfied with the final roll with the following, but was I really?
V1=Northern Electric 12ax7
V2, V3 = Mullard reissue
V4 = Preferred Series 7025
V5, V6 = CV4004
V7 = Sovtek LPS

Once I got the amp chassis back into the shell and back in place on top of the 412 the following day, I was not completely satisfied. Since I only had a limited number of tubes to share between 3 Mesa Boogies, I discovered the Preferred Series 7025 had some interesting characteristics in the Mark IV that I wanted to take advantage of with the Mark V. I had to consider the purpose I use each amplifier. Mark IV I have set up for Heavy metal duty. Tightness of the low end is important as well as clarity on the RH1 channel. The PS 7025 definitely improved tight response on the low end frequencies and did not seem to compress the signal under extreme gain. I decided to revisit rolling the Mark V to determine if there is yet a better tube combination. Reasoning why the revisit, one voice in the clean channel got overlooked since I do not use it that often. TWEED. I never cared much for it since it adds to the brittleness of the amp. Perhaps I just have not figured out how to dial it in. I found the NE 12AX7 to be too much tube for the TWEED setting. Also I really loved the character of the NE12AX7 in the RA100 the most. I will get back to that later.

Starting over again with the Mesa originals that came with the Mark V (I would be considered a tube hoarder, if it still sounds good I hold on to it). So back to the bench mark to verify tube changes once again. First I only focused on V1 which is typical since this sets the stage for the tone and character of the amp. There are other tube positions that will greatly affect overall tone and gain structure of the amp as well as its character that will be more noticeable (V2, V4), and the remaining will just affect gain structure and not be as much of an effect on tone. This time I cycled many different guitars though the channels, and this time I adjusted all the controls associated with the channel. I try to avoid ear fatigue so I only do it in short to medium length sessions at various power levels. The NE tube is great, it is precise and well balanced in frequency response based on hearing alone. I would love to se BODE plots for each tube (basically a full sweep of frequencies of a simple sign wave signal showing the peaks of amplitude for the range of frequency, if you ever saw a response curve on a speaker, that is a BODE plot.) However, the Mark V is design to enhance the gain structure by shifting the operating point of the triodes for different channel selection.
The NE tube is perfect for Jazz, Blues, Country, etc… that will create a slight bit of compression but not excessive. Probably why I liked it so much as the primary of the clean channel in the RA100. It sounds great for CH2 and CH3 but the compression increases due to the voltage shift. CH2 runs the coldest on V1 for the low frequency enhancement, and highest for the bright attack and increased gain for CH3. That being said, CH2 was losing the tight low end that I liked in Crunch Mode. It was not that dramatic but noticeable. Definitely much weaker with the Mesa JJ type tube. My favorite tube for V2 is definitely the Mullard reissue. Using this tube in V2 really brings out the complex harmonics of the power tubes. Since the signal passes through V1A followed by V2A and then through V1B, V1 in general will have the greatest impact on attack for CH2. Side effect is the character in gain and low frequency roll off and mid frequency punch. Experimenting with the other tubes in my inventory I found the Preferred Series 7025 (or if you like Ruby HG) to keep the signal tight and defined. Effect on CH1 is dry piano like tones, the boldness and chime is preserved without compression. CH3 also benefits from the lower gain structure of the 7025 such that Mark IV mode has more definition but yet still has great high gain structure. I found an improved overall enhancement with the PS 7025 in V3 and V4. No matter how much I like the NE 12AX7, I think the PS 7025 delivers great tone to all 3 channels without losing the edge or rolling off the high end too much. Definitely an improvement and will stand out in the mix without being ear piercing as is the case the Mesa 12AX7A. Also the V4 reverb driver tube really alters the tone of the amp considerably as well. I have tried many tubes with different results. CV4004 will brighten up the reverb as well as add more compression to the CH3 gain. The PS 7025 I believe worked the best for reduction in noise from the reverb driver and kept the CH3 gain more on the tight side. On the flip side, the CV4004 sounded the best in V5 and V6 compared to the other tubes. The compression is just enough to keep the traditional gain structure of CH3 where as the PS 7025 in V4 keeps it out of the mud.

I did try other tubes in V7 just to hear the difference. Not much to be said here. JAN/GE 5751 improved overall performance when driving KT77, the Sovtek 12AX7 LPS seemed to be the best for its intended duty. I primarily use the Mark V for classic rock, heavy metal, all of that in between and on the light side Blues and Jazz (try to anyway). Since the RA100 does not have a pristine clean, it is more of a dirty clean, so I do not mind a tad of edge. The NE tube worked well but I got a greater degree of clarity with the PS 7025. In addition to that, I found the PS 7025 to have the lowest noise floor. With no signal input, each channel had minimal power supply noise or hiss. This was comparable to that of the old Mesa Chinese tubes I still have from the early 90’s. What I finally wound up with in the Mark V:

V1, V3, V4= Preferred Series 7025
V2 = Mullard reissue
V5, V6 = CV4004
V7 = Sovtek LPS

You can get similar response with just changing V2 to a Mullard reissue and keeping the rest as Mesa 12AX7A (JJ). Another trick is to use a Mesa 12AT7 in V4, this will drop the influence on the reverb and improve the noise level or hum if that seems to be an issue, and increase the headroom of the CH3 gain structure. CH3 Mark IV mode will sound closer to the CH2 Crunch mode. I have also tried the Mesa 12AT7 in V2 and the effect is similar to the PS7025 for CH3 and CH2 but you lose the crispness of CH1. If I did not care about using CH1, the Mesa 12AT7 can really enhance the tone and character of CH2 and CH3. I may go back to this later. For now I am set with my final roll in the Mark V.