Tube replacement with other than Mesa or Groove Tubes.

[bandit2013]

When it comes to preamp tubes, it has been a hit or miss. The current Mesa 12ax7 are JJ tubes (or at least they both use the same source). For power tubes, Mesa STR440 are Ruby tubes. There EL34 is the same as EH EL34 or perhaps the Sovtek version of the same tube. The best tubes I had that were Mesa branded tubes that were made in the past 14 years were the coke bottle STR420. However, I have found nothing to sound better than SED =C= 6L6GC in the Mark V. The TAD 6L6GC-STR are really good tubes too. KT77 gold lions are extreme in the Mark V. I have tried them in the RA100 and they are okay but do not surpass the SED =C= EL34.

I have done the TS, EH, JJ, Sovtek, and Mullards (all current production) in various positions. What I favor the most is the following:

Mark V head:
Power Section:
SED =C= 6L6GC best performance for all types of styles (favorite but also like TAD6L6, 6CA7, EH EL34, and GL KT77) Note on TAD and KT77, they are the best for Heavy Metal styles.
EH 5U4G rectifier
Preamp: V1, V3 (current production Mesa branded JJ tubes)
V2, V4, V5, V6 (old production Mesa Chinese tubes with the square getter)
V7 Sovtek LPS

RA100 head:
Power Section:
SED =C= EL34
Preamp: V1, V4 (old production Mesa Chinese tubes with square getter)
V2, V5, V6 (current production Mesa branded JJ tubes)
V3 NOS RFT 12AT7
V7 Sovtek LPS

Mark IV Combo:
Power Section:
Svetlana 6L6GC (made by Reflector company who produces TS, Mullard, Sovtek, etc....) these are not SED tubes.
Preamp: V1-V4 Tung Sol 12AX7 (these sound the best on all channels, Also have had great success with EH and Mesa but the TS have the best tone for this amp).
V5 Mullard reissue (very much the same tube as the Sovtek LPS)

Not related but here it is anyway: Carvin V3MC
Power Section: Mullard reissue EL84 ( I would definitely recommend these for the TA series amps, originals were Sovetek but the Mullard has a bit more bite even though it may be the same tube), Bias set to 80mA total (20mA per tube)
V1 Mesa/JJ tubes, V2 Jan/GE 5751 (needed to cut the abundance of high gain)
V3 Mesa old Chinese tube with square getter (best overall tube for clean channel performance)
V4 (PI) Mullard 12ax7 reissue.

 

[shimmilou]

...Mullard reissue EL84 ( I would definitely recommend these for the TA series amps, originals were Sovetek but the Mullard has a bit more bite even though it may be the same tube)...

That shows the difference in tastes, I tried the Mullard RI in my TA-15 and preferred the stock tubes (which I believe are EH, at least in my amp). The Sovtek, EH and Mullard reissue are definitely not the same tubes, you have to look closely but the differences are apparent. The getters can be one of the easier things to spot, and they are different on the EH and Sovtek. Other things like the heaters, supports and grids can be more difficult to see, but do show that all three are very different tubes. Probably the best test is the sound difference as you pointed out.

The Mullard reissue has a spiral heater and uncoated screen grid posts:


The EH has a straight heater and coated screen grid posts:

 

[bandit2013]

As with any amp, the difference between brands, and models is the final output and how it sounds.

I did not look extremely close enough to accurately indicate same or different. The tone between the two was night and day. At a quick glance they appear to be the same. I think what made the difference in the Carvin amp was the bias adjustment. It was way off for the Sovtek tubes from the start.

Even if the tube looks similar, the only way to find out for sure is to take it apart, then do a forensic on the plating, core materials, etc.... Case is the Sovtek 12ax7LPS looks identical to the Mullard reissue 12ax7. They even sound the same as a primary V1 tube (not recommended since they both can be mechanically noisy) but they perform well as a current driver tube like the PI.

Since I do not have a TA-30, perhaps the statement was poorly stated. Not the same amp as a Carvin V3MC, but since they both use EL84, perhaps they would sound good in the TA or other amps. My findings between the two tubes Sovtek and Mullard (sure made by same company) sound completely different. If I had something that compares to the tone of the V3MC, it would have to be the Mark IV, they nearly sound the same but yet different amps in all respects. I will leave the unrelated out.....

 

[shimmilou]

Good point, it probably has a lot to do with the amp settings as well as the particular amp model. I use the "Normal" on channel 1 and the "H1" on channel 2 for my TA. For other owners of the same amp that use "Top Boost" for channel 1 and "Tweed" for channel 2, some said that they preferred the Mullard RI output tubes, and/or Tung Sol preamp tubes.