Mesa 400 tube recommendations

[clankenstein]

No love for a 12bh7 driver then?

[rockbobmel]

I still have some 12HB7 tubes.  Some vintage and a new EH.

[rockbobmel]

I just picked up a EH 12AU7 and the controls have more usable range. I don't know if it sounds much different. Maybe lost some honk.   Input 2 is still quite touchy.

[Psycho Bass Guy]

12BH7's would be more of the same  effects as the 12AU7 except that the 12BH7 is not a direct drop-in replacement for the 12AX/AT/AU7 because it requires double the heater current, but it should work OK with no issues. There's not enough clean consistent power in the supply rails to make the 12BH7 any better than the 12AU7 in practice anyway. The 12BH7 does have more output power to drive the power section, but no matter how much harder the output stage is driven cleanly, the Mesa is 225 watt amp. 

[gearHed289]

Fascinating thread. I always wondered about the 12AU7 driver in my SVT III Pro.

[rockbobmel]

Thanks PBG.  Will the 12AU7 make the tranny run hotter than a 12AX7 ?
 
225 Is way plenty for me these days. We have a laid back blusey band now (Allmans, Steely). The Alice In Chains tribute is over (Ear Plugs!).

[slinkp]

Isn't 225 watts from a tube amp kind of a lot of power anyway? :-0
I mean, that's less than an SVT but a lot more than a V4... How many other amp choices were there in that power range back when the Mesa came out?

[rockbobmel]

There were always big tube amps around. I think My Mesa dates around (2000).  I also have a V-4 (Magnavox 1972) and a Sunn 2000S (1969) that I could use and have more than enough power for me, but the size of the heads and antiquity make them stay home.

[Psycho Bass Guy]

Thanks PBG.  Will the 12AU7 make the tranny run hotter than a 12AX7 ?

No. It's a direct replacement.

[rockbobmel]

Nice.  Thanks.

[rockbobmel]

One more question. I have 3 - JAN GE 5751 tubes just sitting.  What could I expect with the 5751 in v3 AND 12AU7 in v4?

Found this in the SD forum.....

Default Re: The Phase Inverter tube. How to choose?
A decent P.I. tube makes a big difference to my ears. Amazingly, those cheap, crappy Sovtek 12AX7As and 12AX7Bs make pretty good ones. As Myles Rose noted, JJ ECC83S tubes do something in the P.I. slot that is not pleasing. I dont' think they do good service there. I think of the GE 5751 as the gold standard P.I. tube. In an amp calling for a 12AX7 P.I., the GE 5751 will bring out the best presence and detail in your amp. That's just my experience.

Lots of folks push the 12AT7 as an ideal P.I. tube. It depends. In some amps, it sounds great in that role. In amps that want a 12AX7 there, the 12AT7 just sounds like it is lacking punch. Let your ears be the judge.

[Psycho Bass Guy]

You'll have a bit less gain and not much else difference aside from whatever tonal curve that make has (brands tend to have their own tonal characteristics). Keep in mind the SD forum is geared to guitar players who equate gain with "fullness" when the two are not necessarily the same or even related in many cases. The Mesa preamp is already so over-gained that taming it too much just makes the amp less powerful, but I don't think a 5751 would sound bad. IIRC, I tried them in mine and the difference wasn't worth keeping them in there. The first stage and tonal gain stages of the Mesa actually NEED the gain of a 12AX7. Also keep in mind that there are different types of phase inverter circuits and it sounds like the link you provided is describing a Fender-style guitar amp with an overloaded preamp driving a slightly lowered gain inverter section for an SRV-type tone. That kind of tone sounds great for guitar, but is not good for bass.

[rockbobmel]

I got a Sylvania 12AX7 in V1, a JJ ECC83 in V2,  a JAN 5751 in V3,  a Sylvania 12AU7 in V4.

I got a chance to dig in a little today running Ch1 at 5, Ch2 at 2.5 and master around 4 all knobs pulled and a smiley EQ, B at 7, T at 6, and M at 5.

I tried it with D410-XLT and a Berg NV215. Oddly the Eden seemed more controlled.

Kinda liking what I am hearing. Of course the real acid test will be live with the Bag End stack. I'll decide eventually between the BagEnd and Berg and dump one.

[Psycho Bass Guy]

The Eden sounding better than the Bergantino makes sense because the Mesa's innate tone and output transformer pretty much roll off the bottom octave pretty steeply and the XLT cabs shine in the low mids.