Mesa Boogie Walkabout Mega-thread Part 10

[amper]

The Walkabout works ok at 2 ohms most of the time, but as the manufacturers of the MOSFETs changed their process the reliability varied all over the place. We went through 4 or 5 different vendors and series over the years, ultimately they were no longer available in production quantities as all manufacturers facing these issues phased them out.

Currently, I recommend a 4 ohm minimum load based on 19 years of hindsight along with not knowing which devices may be installed in any amp.

I kind of suspected it might be something like that.

 

[J_WELF]

This is my plan. I have one 12 and want another for outdoor/non FOH support.

I’d concur with this. I played a few gigs with my old band (very/too loud) after I got my Walkabout Scout 12, and it wasn’t enough. Almost, but not quite.

Now, my original plan was to actually get two of these, and use them both for rock gigs and one for quieter stuff, but I ended up leaving that band the next year and haven’t had a full-on rock gig since. At some point, I plan on starting a new band, but I plan to be on guitar for that. My bass work will probably be mostly quieter stuff, so the one Scout 12 is fine.

I kind of wish I had the Scout 15, now, but that ship sailed long ago, and if I ever go back to playing rock bass live, at that point, I will probably go for the Subway rig.

 

[Leo was right]

At 2 ohms at full throttle you are looking for trouble.

 

[amper]

At 2 ohms at full throttle you are looking for trouble.

I’m always looking for trouble. :giggle:

 

[pfschim]

At 2 ohms at full throttle you are looking for trouble.

yep!
I am one of those that ran my WA at 2 or 2.67 ohms fairly regularly in the past. It never seemed to hurt it until it did ... I was running it pretty full blast in a hot environment on a 2ohm load and it shut down (luckily, just the thermal protection circuit). I discovered a neat aspect to the WA in the process ... the DI must be outside the thermal protection loop and apparently does not shut down, and as I was fully in the FOH on that particular gig, I was able to finish the show without flinching.

I'll have to admit though, that when I had my WA back at home the next day, I crossed my fingers before powering it up, hoping that I had not caused any serious problems or burned it out. Happily, I had not and I no longer even consider running it at anything other than 4ohms min.

That experience made me a believer in following the manufacturers guidance.

 

[amper]

That experience made me a believer in following the manufacturers guidance.

While that’s always a good idea, in this case, it was the manufacturer stating awhile back that the Walkabout was perfectly stable at 2 Ohms. At some point, they pulled back from saying that, but it was not an imaginary occurrence.

 

[pfschim]

While that’s always a good idea, in this case, it was the manufacturer stating awhile back that the Walkabout was perfectly stable at 2 Ohms. At some point, they pulled back from saying that, but it was not an imaginary occurrence.

not quite sure what your on about with your post but yes, I have one of the early WA models (actually v2) where Mesa said it was (more or less) ok to use it at 2ohms. But after using it that way any number of times over several years of gigs, I had the experience of having it shut down that I wrote about just above. So, no more 2ohm operation for my WA. The other issue, that @agedhorse has mentioned, is that the MOSFETs used in the original WA design started to be less consistent and are no longer being made (?) .... so, I am not willing to ruin one of the best amps I have ever used in 50+ years of playing .. because I killed it doing something that the manufacturer said is not recommended.

you, of course, are welcome to do what you like with your gear.

good luck!

 

[amper]

not quite sure what your on about with your post

What you said in your comment implied that running the Walkabout at 2 ohms was against the manufacturer’s recommendations. I was pointing out that that was very much not actually the case. The manufacturer did indeed publicly endorse running the amp at 2 ohms, in the past.

 

[sunbeast]

What you said in your comment implied that running the Walkabout at 2 ohms was against the manufacturer’s recommendations. I was pointing out that that was very much not actually the case. The manufacturer did indeed publicly endorse running the amp at 2 ohms, in the past.

Mesa stopped OK’ing 2 ohm operation (at least without caveats) for the Walkabout a long time ago. Given info that agedhorse has access to, it seems the amp went through far more changes over its lifetime than most of us were ever privy to, yet TB has mostly kept that old flame alive about 2 ohms being safe long after various changes to the amp and components may have rendered that info false (and long after Mesa stopped suggesting it was safe in manuals or via telephone). It may be that older versions run consistently safer at 2 ohms, there should be no reason to assume that what was said about those ones should necessarily apply to newer models. And it is generally wise to trust when a manufacturer changes their tune even about older gear, because they have access to far more info about what is actually happening to their gear (both design changes over time and long-term reports and repairs from the field)

 

[amper]

Mesa stopped OK’ing 2 ohm operation (at least without caveats) for the Walkabout a long time ago. Given info that agedhorse has access to, it seems the amp went through far more changes over its lifetime than most of us were ever privy to, yet TB has mostly kept that old flame alive about 2 ohms being safe long after various changes to the amp and components may have rendered that info false (and long after Mesa stopped suggesting it was safe in manuals or via telephone). It may be that older versions run consistently safer at 2 ohms, there should be no reason to assume that what was said about those ones should necessarily apply to newer models. And it is generally wise to trust when a manufacturer changes their tune even about older gear, because they have access to far more info about what is actually happening to their gear (both design changes over time and long-term reports and repairs from the field)

Yes, that’s been covered to a great extent already. Why do people keep repeating the same thing over and over? *No one* is recommend that *anyone* run the Walkabout at 2 ohms, anymore. Not Mesa, not me. Sometimes I wonder if people even bother reading what’s actually on the page.

 

[pfschim]

Yes, that’s been covered to a great extent already. Why do people keep repeating the same thing over and over? *No one* is recommend that *anyone* run the Walkabout at 2 ohms, anymore. Not Mesa, not me. Sometimes I wonder if people even bother reading what’s actually on the page.

ok, fair enough, although you did make a comment about "looking for trouble" (however light hearted that might have been intended) .... and to be honest, I was not always clear about what you were getting at in some of your posts ..... and I did read, and in some cases, re-read what you posted.

Seems like were all on the same page about not running the WA at less than the 4ohms suggested by Mesa.

 

[sunbeast]

Yes, that’s been covered to a great extent already. Why do people keep repeating the same thing over and over? *No one* is recommend that *anyone* run the Walkabout at 2 ohms, anymore. Not Mesa, not me. Sometimes I wonder if people even bother reading what’s actually on the page.

Before agedhorse was posting in this thread feeling out the future of the Walkabout (that eventually led to the WD800) it was still fairly common for people to give their own empirical evidence that it was OK in moderation, probably egged on by old manuals and lots of other people doing the same. I’ve been on this thread many years at this point and only ever read a few contrary opinions to that thread of logic over all those years until the last few when ‘horse came along (incidentally starting just before the time the Walkabout was discontinued)- that is many years of searchable posts feeding a questionable idea. I’m glad we have a Mesa rep on the thread now to set the record straight based on knowledge of the circuit and parts, because that internal knowledge was strikingly absent from this thread for a decade+.
I certainly never accused you of anything!

 

[Al Kraft]

Yes, that’s been covered to a great extent already. Why do people keep repeating the same thing over and over?

I think it's just conscientious folks trying to be sure old folklore doesn't cause new WA owners a problem. Depending on where you start reading and when you stop it would be easy to get a very wrong answer even on TB and/or in this thread. I'm shocked almost every day when someone argues an opinion or internet myth against proven engineering/mathematical/physics realities.

IME most TB folks are just trying to be sure important facts and sound engineering context stay front and center.

 

[EdwardofHuncote]

...The other issue, that @agedhorse has mentioned, is that the MOSFETs used in the original WA design started to be less consistent and are no longer being made (?)

Say what?
Is there a suitable replacement, or are they not fixable anymore?

*sorry if this is well-known well-covered... I will go looking.

 

[agedhorse]

Say what?
Is there a suitable replacement, or are they not fixable anymore?

*sorry if this is well-known well-covered... I will go looking.

They are still repairable, we do have a stock of parts for in-house repairs, but we can no longer get production quantities reliably anymore.

Also, the exact parts used in the early Walkabouts (and some other models) must be substituted by later parts because that vendor/part is long gone.

 

[StayLow]

... I'm shocked almost every day when someone argues an opinion or internet myth against proven engineering/mathematical/physics realities.

I think this latest iteration of "2 Ohms stable" was in the spirit of saying the OP hadn't hallucinated it.

That's true; it was in the official manual. I have it. There was a story about running it overnight at 2 Ohms in testing at Mesa. The original combos were OEM 4 Ohm as were the extension cabs. 8 Ohm combos or cabs were a special order: I have the Mesa catalog that states so.

Then things changed, and here we are.

None of this is meant to recommend 2 Ohm operation and certainly isn't meant to contradict Agedhorse. It feels filthy to even have to type such a caveat, but there it is.

 

[Al Kraft]

I think this latest iteration of "2 Ohms stable" was in the spirit of saying the OP hadn't hallucinated it.

That's true; it was in the official manual. I have it. There was a story about running it overnight at 2 Ohms in testing at Mesa. The original combos were OEM 4 Ohm as were the extension cabs. 8 Ohm combos or cabs were a special order: I have the Mesa catalog that states so.

Agree 100%...I have that original manual and read those same comments. My very early WA Scout 112 is in fact a 4 Ohm version and all the inventory at that time was 4 Ohm unless special ordered.

 

[MuthaFunk]

I bought a twin 4 ohm setup in 2010 that was at the time the standard. The 8 ohm was indeed a custom order then.

But Mesa clearly didn’t have true alignment through the Walkabouts design, specs, and sales.

So you wanna run your Mesa Walkabout Scout at 2, 2.6 Ohms?

At least for me, I’ve ran my WA under 2 ohm loads many many times over the years with the mods outlined in the link above. I guess my particular mosfets were spec’d out ok!

 

[MuthaFunk]

I bought a twin 4 ohm setup in 2010 that was the standard scout cab impedance at the time. The 8 ohm was indeed a custom order then.

View attachment 4227693

But Mesa clearly didn’t have true alignment through the Walkabouts design, specs, and sales.

So you wanna run your Mesa Walkabout Scout at 2, 2.6 Ohms?

At least for me, I’ve ran my WA at 2 ohm loads many many times over the years with the mods outlined in the link above. I guess my particular mosfets were spec’d out ok!

Updated this post because of my poor grammar. I don't know why but I couldn't figure out how to edit the original.

 

[MuthaFunk]