Mesa Boogie Walkabout Mega-thread Part 10

[Al Kraft]

An efficient 212 cab for a truly wonderful amp. Yessir!!!
Be prepared for great tone:
The Eagle Scout.
Boogie Sounds Amazing.
View attachment 2991076

You know that Eagle Scout thing really works Phyzzbin! Red, white and blue for made in America, you'll always "Be Prepared" to impress on a gig with Mesa gear, and BSA could even stand for "Boogie Sounds Awesome", although amazing works too.

This whole Eagle Scout deal is finally starting to come together for me...hopefully the Boy Scouts will be cool about having their premier rank pirated...well, there's always a wall or two you'll run into when you're pioneering new concepts.

 

[bumble yeti]

You know that Eagle Scout thing really works Phyzzbin! Red, white and blue for made in America, you'll always "Be Prepared" to impress on a gig with Mesa gear, and BSA could even stand for "Boogie Sounds Awesome", although amazing works too.

This whole Eagle Scout deal is finally starting to come together for me...hopefully the Boy Scouts will be cool about having their premier rank pirated...well, there's always a wall or two you'll run into when you're pioneering new concepts.

Glad you chimed in Al.
Re: the logo. I really didn't see my concept as a BSA rip off. I just needed a photo quickly to take a shot at the 2 ohm thing. C'mon folks, just because it can doesn't mean it should. It's been written here a hundred times. Better to have a more efficient cabinet(s) with more drivers.
FWIW, the cab could have been marketed as the "Eagle" in the Scout cabinet lineup, avoiding trademark issues. I dunno.
I saw the Eagle Scout as the culmination of everything the Scout cab line could have been. A highly efficient, loud, transportable 212 that's made for the WA… and those of us who don't have roadies… and is all Boogie!!!
I highly doubt that they'll make a cab for an amp that's been discontinued.
But, if they do, you read it here first!
Hmm. Wonder if any progress has been made on my WA tube OD pedal? drool
Edit: I think your Bergantino CN212 may be a great solution!

 

[MarkA]

Interesting. The question comes up regularly on the Walkabout driving 2 ohms, but it really doesn't do it well (and there is certainly some variance between each amp as the MOS-FET's are never going to be perfectly matched in both current sharing and symmetry to the driver circuit. Each one is a little different and has different thermal margins, not unlike tubes in an output stage.

IIRC it was described as safe (but not recommended) to use the amp at 2 ohms when not cranking it in the early manuals and emails with Mesa CS, which is what started the confusion. I'm guessing that there were enough overheating issues that came through CS that they stopped calling it safe at all at some point (a wise decision!).

Every player had a different interpretation of what "cranking it" means. It goes back to my qualifications in many of my recommendations that good common sense, good judgement is needed when driving gear hard, and accidents do sometimes happen.

I recall speaking with someone (I don't recall whom) at Mesa, years ago, and being told that the Walkabout would be fine at 2 Ohms. I never did run mine at 2 Ohms -- and never ran it below 4 Ohms on a gig -- but I did contemplate a 2.67 Ohms setup. The conversation of late has trended against running the Walkabout at 2 Ohms, but I got the impression that 2.67 was both considerably safer and a "sweet spot" for making the most of the Walkabout (i.e. running three 12s or something similar).

I realize that "making the most of the Walkabout" will depend on your goals (which included clean volume on louder outings, in my case -- for others it might mean pushing the amp into compression and overdrive), but is 2.67 Ohms frowned upon now, too? Or is it just a case of "use your judgment"? There has been less of a hard line drawn with the Walkabout, historically, with regard to minimum load than with many other SS amps -- but I suppose that any amp can shut-down or incur damage (even with a nominally "safe" load) if flogged hard enough.

 

[Coolhandjjl]

I suppose one could get another Walkabout and slave it. A pair of 212s or 215s with one head driving each cab.

 

[Al Kraft]

I recall speaking with someone (I don't recall whom) at Mesa, years ago, and being told that the Walkabout would be fine at 2 Ohms. I never did run mine at 2 Ohms -- and never ran it below 4 Ohms on a gig -- but I did contemplate a 2.67 Ohms setup. The conversation of late has trended against running the Walkabout at 2 Ohms, but I got the impression that 2.67 was both considerably safer and a "sweet spot" for making the most of the Walkabout (i.e. running three 12s or something similar).

I realize that "making the most of the Walkabout" will depend on your goals (which included clean volume on louder outings, in my case -- for others it might mean pushing the amp into compression and overdrive), but is 2.67 Ohms frowned upon now, too? Or is it just a case of "use your judgment"? There has been less of a hard line drawn with the Walkabout, historically, with regard to minimum load than with many other SS amps -- but I suppose that any amp can shut-down or incur damage (even with a nominally "safe" load) if flogged hard enough.

If I've understood agedhorse's posts in the past correctly, below 4 Ohm operation is moving you dangerously close to an operational regime that is not consistent or exactly predictable amp to amp. I'm paraphrasing here, but as I understand it there is a unique relationship between the pre-amp and power section that creates the tone we all love, however, it is almost an anomalous sweet spot that can't be pushed further without sometimes (depending on tolerance stack-up in components and EQ settings) generating way too much heat. I would sort of describe it as a "magic tone" that works within a very narrow band and isn't something that can be simply scaled up (power-wise) - or they would have done it years ago.

I'm sure agedhorse would have said it better, but my take-away from his posts is that the WA is a solid 4 Ohm head if you value dependability (no thermal shut-downs on gigs) and long term reliability (heat is not the best friend of electronic components). If you're willing to gamble a bit and the risk is worth it, the WA can be run at 2 Ohms, but it's not recommended.

 

[bumble yeti]

If I've understood agedhorse's posts in the past correctly, below 4 Ohm operation is moving you dangerously close to an operational regime that is not consistent or exactly predictable amp to amp. I'm paraphrasing here, but as I understand it there is a unique relationship between the pre-amp and power section that creates the tone we all love, however, it is almost an anomalous sweet spot that can't be pushed further without sometimes (depending on tolerance stack-up in components and EQ settings) generating way too much heat. I would sort of describe it as a "magic tone" that works within a very narrow band and isn't something that can be simply scaled up (power-wise) - or they would have done it years ago.

I'm sure agedhorse would have said it better, but my take-away from his posts is that the WA is a solid 4 Ohm head if you value dependability (no thermal shut-downs on gigs) and long term reliability (heat is not the best friend of electronic components). If you're willing to gamble a bit and the risk is worth it, the WA can be run at 2 Ohms, but it's not recommended.

The man just said it on Thursday:

The question comes up regularly on the Walkabout driving 2 ohms, but it really doesn't do it well (and there is certainly some variance between each amp as the MOS-FET's are never going to be perfectly matched in both current sharing and symmetry to the driver circuit. Each one is a little different and has different thermal margins, not unlike tubes in an output stage.

 

[Al Kraft]

The man just said it on Thursday:

I knew I'd read that somewhere...thank goodness the subject wasn't what I had for breakfast this morning!

 

[agedhorse]

There are also considerable variations in how some speaker designers define nominal impedance, and how much sub-nominal impedance is considered acceptable.

Those who also design amps tend to be more respectful of this region.

 

[Al Kraft]

There are also considerable variations in how some speaker designers define nominal impedance, and how much sub-nominal impedance is considered acceptable.

Those who also design amps tend to be more respectful of this region.

Duke actually addressed this in a couple posts a while back regarding his cab designs and I had never really thought much about it until then. I think we all know that impedance varies with frequency, but I for one didn't realize how much variance there could be in loudspeaker.

After doing some reading on this topic I now wonder if it helps explain why many people often feel they get the best sound/tone/performance from their rig when everything is from the same manufacturer. Not to say you can't mix and match cabs and heads (and I do), but if you tend to be a frequent 2 and/or even 4 Ohm high power level operator, it might make sense to pay greater attention to technical product specs if they're available.

IMO this is an area where manufacturers openly sharing their knowledge and product design approaches with us on TB can be especially helpful.

 

[bumble yeti]

There are also considerable variations in how some speaker designers define nominal impedance, and how much sub-nominal impedance is considered acceptable.

After doing some reading on this topic I now wonder if it helps explain why many people often feel they get the best sound/tone/performance from their rig when everything is from the same manufacturer.

Hence the reason I want to keep my Boogie, all Boogie.

 

[bumble yeti]

Hey Al or anyone,
Got any experience with the Bergantino HDN212? Please correct me if I'm wrong but it looks like the CN212 may be out of production.

 

[Al Kraft]

Hey Al or anyone,
Got any experience with the Bergantino HDN212? Please correct me if I'm wrong but it looks like the CN212 may be out of production.

The CN212 is out of production AFAIK. I suspect the HDN212 is close and may be a little fuller in the deep lows from what I've read in user reviews, but I have not yet played an HDN cab.

 

[bumble yeti]

The CN212 is out of production AFAIK. I suspect the HDN212 is close and may be a little fuller in the deep lows from what I've read in user reviews, but I have not yet played an HDN cab.

Yessir. I watched a comparison on YouTube and came away with the same impression. Looks like that's going to be as close to our Eagle Scout as we're gonna get, my friend.
Unless Andy's got something in the works he'd like to share.
My b-day's just around the corner and, tho I ain't happy about being another year older, it does have a tendency to bring a bright, shiny object to my door.

 

[Al Kraft]

Yessir. I watched a comparison on YouTube and came away with the same impression. Looks like that's going to be as close to our Eagle Scout as we're gonna get, my friend.
Unless Andy's got something in the works he'd like to share.
My b-day's just around the corner and, tho I ain't happy about being another year older, it does have a tendency to bring a bright, shiny object to my door.

As much as I love my Mesa gear, I've never had a disappointing moment with a product that said Bergantino on it. The only thing I will say about my CN212 is that if Mesa had built it, I think the cab covering might have been a little more robust, but now we're talking about nits, not meaningful stuff if you're careful with your gear.

 

[BassPilot]

I just got a Bergantino AE410. I've tried my walkabout through it at home but it's just silly to think I'll get an idea of what the Walkabout sounds like through it in my home office/music room.
I have turned the master up to about 3 o'clock and gain no higher than 10 o'clock. I can tell you that there is quite a bit more clean headroom (quite loud) than with my 2 12" Scout cabs. I'm looking forward to gigs on 5/5 and 5/12 where I can put it through it's paces and see what this combination sounds like. Oh Boyoboyoboy!!!

 

[Al Kraft]

I just got a Bergantino AE410. I've tried my walkabout through it at home but it's just silly to think I'll get an idea of what the Walkabout sounds like through it in my home office/music room.
I have turned the master up to about 3 o'clock and gain no higher than 10 o'clock. I can tell you that there is quite a bit more clean headroom (quite loud) than with my 2 12" Scout cabs. I'm looking forward to gigs on 5/5 and 5/12 where I can put it through it's paces and see what this combination sounds like. Oh Boyoboyoboy!!!

IIRC that's a 4 Ohm cab and has pretty high sensitivity - all part of the perfect formula for getting the most from a WA.

 

[BassPilot]

IIRC that's a 4 Ohm cab and has pretty high sensitivity - all part of the perfect formula for getting the most from a WA.

Yessir

 

[MarkA]

Thanks to all who chimed in re. my impedance question.

At the risk of being tedious, though, I was asking specifically about 2.67 Ohm operation -- I apologize if the answer should be obvious or has already been clearly given, but the difference vs. 2 Ohms seems, to me, not academic. I've owned amps rated for 2 Ohms minimum and others rated specifically for 2.67 Ohms minimum (and, of course, 4 Ohms minimum).

I did have a look at the most recent manual. As of now, it reads...

...can be used to drive any two speaker cabinets via the two SPEAKER OUTPUT jacks, with a combined overall load of 4 Ohms being the preferred impedance...
​

and

SPEAKER OUTPUT: The WalkAbout provides two 1/4 inch speaker jacks for powering speaker enclosures.The recommended speaker load impedance for the WalkAbout is 4 Ohms, at which the mighty SIMUL STATE power section is capable of delivering a whopping 300 watts RMS before clip and peaks of over 400 watts!

A speaker load of 8 Ohms may also be used though the overall power will be reduced to roughly 150 watts using this rate of impedance.​

I guess that inclines things further toward 4 Ohms -- it's the "recommended speaker load" -- though the manual never explicitly states a minimum load.

Does Mesa have an "official" position re. running the Walkabout at 2.67 Ohms? (Would doing so, for instance, void the warranty on a head purchased in the last 5 years, or is that more of a gray/discretionary area?) Is a 2.67 Ohm load (one-third higher nominal impedance than a 2 Ohm load, one-third lower than a 4 Ohm load) considered significantly safer for the head than a 2 Ohm load, or does it just depend?

More generally, is a lower impedance load, in-and-of itself, more dangerous for a SS amp, or more dangerous simply because it allows the amp to push more power (potentially more than it can safely handle)? With the Walkabout, for instance, would pushing 200 Watts at 2 Ohms stress the amp more than pushing 200 Watts at 4 Ohms? Are there other risks (instability, etc.) that I don't see?

Duke's point (echoed by others) about some speakers and cabs with the same nominal impedance representing more varied and challenging loads to amplifiers than others is a good one (and I think that there are several builders who are cognizant of this), as is the point that discretion must be employed when pushing gear hard.

To be clear, I don't (as I've mentioned earlier in this thread) have a Walkabout anymore, but I retain some fondness for and interest in that little amp.

Thanks in advance for any light shed.
-Mark

 

[Al Kraft]

I did have a look at the most recent manual. As of now, it reads...

One paragraph you didn't include that kind of hints at the possibility of an answer other than 4 Ohms as the minimum. It's this one from the link you included (it's right up front in helpful hints) but the type I put in bold sort of says to me, "but don't do it as a usual and frequent practice":

2. The optimum speaker load for your WalkAbout is 4 Ohms. You may use a cabinet (s) of a higher rating safely (8 Ohm) with no degradation in tone, however the amplifier will not produce its full rated wattage. Minimum load rating is 2 Ohms and while the WalkAbout will handle this lower load condition - and in fact produce more than its rated power, it is not recommended. Prolonged use of a 2 Ohm load will cause the power mosfets to run hot causing the protection circuit to trigger and mute the output signal until such time as the mosfets can return to a safe operating temperature. Avoid using 2 Ohm loads whenever possible.

Please note that I have no special insights and am not representing there is a "legal loophole" here to run 2 Ohms. As an engineer this really screams to me: Run it at 4 Ohms and no lower if you want to be a happy customer in the reliability department (both on a gig and relative to service life).

In the commercial aviation world pilots often do not use the full power an aircraft's engines can produce on take-off, but calculate a needed upper power level for the specific conditions. This doesn't mean the engines can't run at maximum power in those conditions, but rather for reasons of conserving life and enhancing long term reliability a lesser power setting is used. Probably a bad analogy, but a case where the engineers recommend you not use everything you've got unless it's an emergency and you really need it, and then only long enough to get you out the situation requiring that maximum power setting.

 

[agedhorse]

One of the challenges of the output stage is the use of dual die parts necessary for the performance. These are great parts but have some inconsistencies and quirks at high temperature simultaneous with high current and high source-drain voltage. This can result in unpredictable behavior, which shows up below 4 ohms.

There is now only one manufacturer of these finished parts, the challenges are quite real for this application.