I have a Walkabout, and I just picked up an M-Pulse 600. I'm trying to decide which to keep. On my Walkabout, the pre starts saturating and breaking up at around 12:00, and there's plenty of grit past there. On the M-Pulse, I can't get it to distort until the knob is maxed out, and even then it's pretty slight. Are the preamps on these two amps different? I thought they would be the same. Could the difference just be in the tubes?
No, they are VERY different. The MPulse's gain structure is voiced to stay quite clean at even high volume levels, and the tone of the pre when it is really pushed is much less aggressive than the Walkabout. The MPulse is NOT a higher powered Walkabout... very different sounding. I greatly prefer the MPulse, but I like it clean. The Walkabout is about 'old school warmth' to me, the MPulse600 is about 'studio clean tube tone', and the BB750 is about SVT type grind and distortion to my ear. IME.
Hmmm. I'm kind of facing this same situation, although in my case, I've been using an M-pulse 600 for over a year, and just acquired a Walkabout (12" Scout combo). Unfortunately, my M-pulse rig is at my rehearsal facility, so I haven't yet had a chance to A/B them, but I will at rehearsal this weekend. I guess the best way to do it will be through the same 410 cab I use for the M-pulse. I always go through the PA at gigs, so I'm seriously considering making the Scout my gig rig. I think it will be a more than adequate stage monitor, and will certainly be easier to haul than the bigger rig. I see great difficulty looming on the horizon (in deciding which one to keep), I'm thinking I will probably end up keeping both.
The Mpulse 600 was my first ever amp with a tube in it, and I was shocked when I found out you COULD overdrive it. Naturally I spent even more time giddily tweaking new tones. I honestly don't know the differences between the two, but this just gave me another chance to pat myself on the back for getting a Mesa.
It does take a bit of tweaking to get the Walkabout to just the right level of tube overdrive. It's very easy to go over the line and get mush. But once you find it it's great. You can just leave it alone after that. Like playing on a very good tube amp with lots of power. I've used the head alone to drive various 8 ohm cabinets and even at the lower output capability at that impedance had plenty of stage volume. Of course some very inefficient cabinets might not work as well. But I certainly have no need for a more powerful version. I've tried the 600 in the store. It's wonderful too but is not the same as the Walkabout. If you need all that power though, it's a great choice. Mesa quality is superb. A step above all the other good amps out there except for a few of the equally expensive limited production bass heads.