Mark III Impressions and tube swaps (long) :)

[edward]

OK, so I'm finally getting a handle on this beast. The R1 was easy to get good tone ...it responded very much like my DC5 clean channel.

The Lead channel is where it took me some time to get accustomed to what's going on. Once I arrived at a pretty good lead tone, I started with some tube swaps.

For anyone interested, I tried a 12AT7 in the V3 and PI slots to lower the gain and smooth out the OD. Very nice creamy quality to the OD overall!! BUT, I lost some of the punch of the ax7s. So I found that putting the ax7 in the V3 but the at7 in the PI was a good compromise resulting in smoother, creamier overdrive than with both ax7s, but still retaining some punchiness of the ax7's character.

I also tried it with the at7 in the V3 and the ax7 in the PI, but liked it better the other way around since the at7 in the PI had the additional benefit of gaining down the R2 channel.

On that last note, the at7 in the V2 seemed to really improve the R2 channel. With the at7 in both the V2 and PI slot, the R2 had a markedly less grainy quality and more bluesy tone, as well as reducing the OD's saturation. This is a must, IMHO. The R2 sounded so much more usable than with the ax7!

Now for power tubes: a pair of Mesa 6L6 420s and EL34s (marked "Bogner") is what came in this beast. I replaced the 420s with a known good pair of 430s and for the heck of it tried the 420s in the outer slots (so 4 6L6s as I've read some do here). It didn't sound "bad," but definitely lost the upper-mid punch of the ELs. So I put the ELs back in to confirm and, indeed, the tone definitely cut through better. At the sacrifice of a bit of 6L6 bottom end, the ELs added an upper-mid voice that definitely was more "in your face" ...in a good way.

So there you have it. I will experiement further, but I think I really like where I am now: 12AX7 in the V1 and V3, 12AT7 in the V2 and PI, and EL34s where they belong. I still have to replace these old/questionable ELs, but I like the overall character. What I have is a MkIII that sings clean and chimey in R1, quasi crunchy and dark-bluesy in R2, and Lead is smooth OD but with a definite raunchy bite to it. I still want to do the R2 volume mod just to notch down the volume a tad to even it out with R1, but overall I am liking it ...I think I'm keeping her.

Anyone else care to share their impressions?

Edward

 

[Schmoog]

Personally, I am running Winged C 6l6's in the middle, yellow mesa EL34's outside. in the preamp, its an SPAX7 in V1, mesa 12AX7's in v2, and v5, and NOS Mullard shield logo made in england 12ax7's in V3 and V4. I think that the problem I had with the gain not being smooth was related to the crappy modern tubes in v3 and v4. the mullards really smoothed everything out, and took any fuzzyness/buzzyness out of the lead channel. you get the same effect with the 12at7's, but because they lower gain, not because they're just phenominal tubes

 

[edward]

Yeah, it definintely had crappy tubes all around, as that's what she arrived with. My DC5 is loaded with some NOS Mullard AX7s as well as a couple of TungSol reissues ...I'll try them out in the V2 and V3, and compare them to the AT7s (which are NOS RCA AT7s in my reverb and PI slots on the DC).

And like you, I have had the winged C 6L6 in my DC (for some time now) and like them ...I should have compared those to the STR430s but didn't think of it at the time as I was focusing on comparing 6L6 vs ELs in the outer pair. I'll swap out the 430s and see what I get. But I see you're using Mesa's EL34s ...have you tried the Svet or SED ELs??

Edward

 

[Schmoog]

I used the mesa EL's because before I got my III, I had a stiletto. I retubed the stiletto, and one of the new powertubes had some really beautiful lightning inside, so I had the amp serviced, and put the old powertubes in to be safe when I sold it. the day I got the III it had 4 6l6's throughout, I went to pull one of the outer 6l6's, and it was really resistant. then it suddenly released, and the tube hit the cabinet and shattered in my hand. and since I had 3 el34's lying around, I just threw em in there and called it a day.

 

[Drew816]

So, any further exploration on this subject? My Mark III Black Cross/Dot will be arriving in a few days and I suspect I'll be looking to 'tame' my #2 and #3 Channels just a touch, so I thought I'd check in and see you all have done any further experimentation?

Thanks,
Andrew
Drew816
Mark III - Rookie

 

[Tuna141]

To tame the "fizz" from the crunch channels turn the Presence way down. . I keep mine around 1-2 and never change it. With it any higher I find the amp too harsh and mushy.

 

[edward]

So, any further exploration on this subject? My Mark III Black Cross/Dot will be arriving in a few days and I suspect I'll be looking to 'tame' my #2 and #3 Channels just a touch, so I thought I'd check in and see you all have done any further experimentation?

Thanks,
Andrew
Drew816
Mark III - Rookie

Hey Drew,

Since you asked...

My final recipe is:

V1: 12AX7 (the special Mesa one for the v1 spot ...but honestly can't tell the diff with a NOS AX7 so decided to keep the Mesa one in there)

V2: NOS Mullard CV4024 (that's an AT7). Wow, another incremental improvement over the NOS RCA AT7s I had in there. Get these, honestly.

V3: NOS Mullard CV4024 also

V4: NOS RCA 12AT7 (I only had two of the mullards, so put the RCA here ...get the mullard if you can, but this RCA is still better than the mesa that was in there).

EL34s: the Mesa 450s ...NOS Siemens. A world better than the dead, old crappy 34s I had in there! But I have no idea if better than Mesa's OE 447s as I couldn't A/B them.

STR 430 6L6s.

Keep in mind I am very skeptical about tubes supposedly "fixing" tone ...they *alter* tone; whether that's to one's liking is another question entirely. But I will say that these changes (through much trial/error) I made resulted in gorgeous tone, from R1 to Lead, and a truly usable R2 that I actually like. If it helps you any, most of the "tonal benefits" I reaped are in the Lead and R2 channels: creamy, smooth, and rich while cutting the high-end bite and OD's "graininess" ...niiice!! YMMV of course, but I am one very happy MKIII owner.

Edward

 

[Drew816]

Thanks Edward, I'll be ordering tubes here shortly and I'll post my thoughts after a bit!

Rock on...