Mesa Walkabout Megathread!

[KJung]

Ok, let me put it this way...

You're facing your "port" down. Mesa's idea is, like Bose's, to use reflection of the low frequency waves to help give it a huge sound. Now, imagine taking that reflective surface and putting sound absorbing material on it, AND, reducing it's output space.

Put yet another way... why do they put soft stuff inside bass cabs? To reduce reflection (which causes standing waves inside the relatively small enclosure), to help keep the sound more coherent... especially when a port is being used.

Again, we're talking about low end here, and generally speaking, stuff that's more noticeable at higher volume settings, so it also depends on how you play and how you set your EQ as to how noticeable it is, but I absolutely guarantee you that you will lose something putting it on carpet that you won't when putting it on a hard surface... also depending on how thick the carpet is and how thick and/or soft the pad is, as well.

So the bottom line is, in short, you've got stuff coming out of the bottom of the cabinet. If you muffle it, you will lose something.

IMHO as always...

Hey Vic! Well, just so you don't think I'm an idiot , of course if the passive radiator acts like a speaker there would be some effect of the material under it. My big question is (and again, I'm just curious about it... not that this is a big issue or anything ), is this... does a passive radiator act more like a port or more like a speaker? My limited understanding of this stuff is that if it acts like a port (primarily to expand the low end capability of the cabinet by tuning the roll-off frequency of the cab lower), then what's under it shouldn't matter so much. However, if the passive radiator behaves like a speaker (i.e., as another directional soundsource) then I would agree that carpet would have more of an effect (although even then you would think that the carpet would affect primarily higher frequencies versus the extremely low ones that I would expect to come out of the radiator.

No big deal... I'm hoping someone who knows about the technical aspects of this chimes in, versus all of us just opinionating on it

As a reminder.....The main point of the thread is that the Walkabout and both versions of the Walkabout Scout sound great, very 'tubey' and very loud and low for their size

 

[vapochilled]

I could be wrong here though... so I'm curious to hear from someone who knows how these passive radiators really function. All I know is, that little 112 cab really put out some serious low end!

A passive radiator is a speaker w/o a magnet & voice-coil. Thus no power. It functions of the excursion of the powered speaker. Doing just the opposite. When the powered speaker excursion is out bound. The passive is pulled in by the movement of air creating vaccum in the enclosure. When the powered speaker retracts. It pressurizes the enclousure. Therin pushing the radiator out bound. Basically moving close to twice as much air. With half the weight.

And on the fans. It's just an 80mm computer fan. In my walkabout it can fit a wide one. Which would have larger blade. And with a pot you can controll the speed. They sell them on the pc modding sites. So you could put in a wider fan. That moves more air. But run it at a lower speed and get the same cooling effect. One thing to note. Mine came with a Sunon fan. They are notorously noisy. So open yours up look up the sunon model number. And google it to find out how much air it moves & the decible level. That will be rated in cfm & db, so plain english. Then google pc cooling fans, ect. Basically any other fan with similar movement. Will be 5-10 db less than those Sunons. But I will warn you Panasonics are loud. Also if its called a tornado it sounds like one, too. lol

 

[KJung]

A passive radiator is a speaker w/o a magnet & voice-coil. Thus no power. It functions of the excursion of the powered speaker. Doing just the opposite. When the powered speaker excursion is out bound. The passive is pulled in by the movement of air creating vaccum in the enclosure. When the powered speaker retracts. It pressurizes the enclousure. Therin pushing the radiator out bound. Basically moving close to twice as much air. With half the weight.

+1 on actually what it is. I think we all get that. The question is what does it literally do. It's interesting how much different information is out there on this. Here's something I pulled from a high end Audio web site that says this is not necessarily the case regarding the direction of the speaker excursion:

3. It may seem logical that the passive would operate somewhat like a lever, with its cone moving out at the same time as the woofer cone moves inward, and vice versa. This is not the case, however. In fact, both cones could move in or out together (this is called "in phase"), or any combination of opposite motions ("out of phase" - the most extreme being "180 degrees" out of phase - like the lever effect described above). Ideally, in order to reinforce each others sound, they would be exactly in phase, but in reality, due to the physics of this sort of resonant system, they are out of phase to some degree most of the time.

It is also interesting to note that at the resonant frequency of the PR, its motion is at a maximum (this makes sense of course), and the woofers motion is at a miminum!

 

[billfitzmaurice]

A passive radiator functions in almost exactly the same fashion as a port. This begs the question as to how a port functions. The mass of air contained within a port (and its associated duct, if there is one) tunes the air mass within the enclosure to resonate at a desired frequency, known as the fb (box frequency). The vibrating air mass within the port also acts as a radiating area, contributing to the system output at and above the fb, although below fb the port output is out of phase with the driver and the system response rolls off at 24dB/octave.

A passive radiator (PR) substitutes a driver cone (with no motor assembly) for the port. The mass of the PR cone instead of the mass of the air within a port tunes the resonant frequency of the enclosure and provides additional radiating area. At and above fb the output of the PR is in phase with the driver output, below fb the PR wave is out of phase. There are a couple of minor differences between PR and PB (ported box) operation but nothing significant.

PRs aren't used much because they are more expensive than ports and aren't as easily tuned.

Put yet another way... why do they put soft stuff inside bass cabs? To reduce reflection (which causes standing waves inside the relatively small enclosure), to help keep the sound more coherent... especially when a port is being used

Close. What stuffing/lining/damping does is absorb midrange reflections within the cabinet. If those midrange reflections aren't damped out they will go back to the cone, arriving there at various phase angles depending on how far they travel, and cause extremely ragged response. In a PB or PR they also would either exit the port or vibrate the PR. In either case the midrange radiations from either the port or PR would mix with those from the driver front wave and again cause ragged response.

Standing waves once were a problem when cabinets routinely had interior distances in excess of three feet. The problem disappeared with smaller cabinets post Theile/Small. In any event damping materials have virtually no effect below 200 Hz, where standing waves could occur within a large enough box.

You're facing your "port" down. Mesa's idea is, like Bose's, to use reflection of the low frequency waves to help give it a huge sound. Now, imagine taking that reflective surface and putting sound absorbing material on it, AND, reducing it's output space.

The Bose 'direct/reflecting' sound is a midrange and high frequency radiation technique, one almost universally reviled by audiophiles, by the way. Using a downfiring port or PR over a carpeted surface has no effect on the low frequencies radiating from same. Restricting the size of the space that a port or PR fires into can couple the air mass in that space to the port or PR mass, lowering of the fb and consequently extending bass response lower. The distance to the floor would have to be quite small to interfere with the cabinet's operation.

 

[KJung]

Thanks Bill! That makes sense to me. I thought that was the case, and my ears told me it was, but I wasn't sure.

 

[Vic]

The Bose 'direct/reflecting' sound is a midrange and high frequency radiation technique

Bill, before I ask, I want to make it clear I'm not challenging your expertise, but I seem to remember info on the 901 series where it was the bass ports that faced the walls/corners of a room, to be reflected, and the mid/highs would come direct from the front facing small (4 or 5"?) speakers. No?

 

[Vic]

Got another...

hey vic, congrats on your mesa you will love it!! I don't have the scout cab, just the head. I have tried sovtek tubes and wasn't really pleased or displeased. I have the stock tubes in there now and it seems to work out just fine for me. I play mostly hard rock music ( think tool, staind etc.) through a ashdown mag410, with a sx j bass and a squire p/j. I really like the mid range growl of this setup. Running @ 8 ohms this rig is plenty loud. I am competing against two guitarists w/ a 100 watts each and a heavy handed drummer and I cut thru just fine. hope this helps. take care. ryan

 

[Vic]

Some interesting info on tubes... fyi...

Do you have the history behind these companies and whether Sovtek is making tubes for EH or vice versa?

They're all the same company. Mike Matthews (who worked for the original Electro Harmonix in the 70's) owns New Sensor, a wholesale importer for Russian electronics. He created the name "Sovtek" for the tubes he was importing in the early 90's and later bought the rights to EH, just as he has recently done with Mullard and Tungsol. All three brands are tubes made in the same factory, which used to just be called "Sovtek."

 

[Vic]

Ok, so I plugged the Telefunkens (NOS smooth plate*) in and let it warm up for about 10-15min. My initial opinion, without yet having gone back to plug the stock tubes in again, is the T's are quieter (the orig's were a little microphonic, but not bad), and the tone seems wider/deeper and clearer/crisper. Still plenty of that tube warmth and growl, just cleaner. Seein' as how I'm generally a hi-fi kinda' guy, this is really workin' for me. I'm going to break the tubes in for a couple days and then try overdriving the thing and see about this warm overdrive these are also supposed to be known for.

Still on my list are some of the "good" Electro-Harmonix's (I assume the same as the EH's Demeter uses), JJ's (Tesla), maybe Mullard, Possibly Jans, and likely some Mesa SP's.

fyi...

* As a side note I got these tubes from a very reputable source with a full money back policy and a good reputation, so I'm comfortable with the purchase. You have to watch out with these "NOS" tubes and the high prices they command. Tempting landscape for scammers. With all the testers out there and their different scales, sometimes it's hard to be assured you're truly getting a tube with very little or no use on it. Some go from the "30's to 40's" some go from 800 or so on up to over 1600, etc. A great playground for number fudging. As with anything else, regardless of "new/NOS" or used, make sure you get a reputable source if you take a plunge on something like this.

 

[billfitzmaurice]

I seem to remember info on the 901 series where it was the bass ports that faced the walls/corners of a room

The 901 uses (it's still around) nine 4.5 inch drivers. Eight are pointed at the wall, or into a corner, and one faces forward. The ducted ports also face backwards. The 'pro' 802 has eight forward facing drivers and two forward facing ducted ports.

 

[Vic]

Thanks, Bill.

 

[tallboybass]

Vic, I think you're on track for mega-thread status!

 

[BillisCool]

I'm thinking about selling my 15" and getting the 2 12" setup...

 

[KJung]

I'm thinking about selling my 15" and getting the 2 12" setup...

Assuming you are talking about the 4ohms Scout 112 cabs, be careful of that 2ohm load. The Mesa Walkabout documentation is wonderfully obtuse on the 2ohm issue... basically saying it's safe but don't do it! I've read a number of posts where TBers are running their Walkabouts at 2ohms, but it just doesn't seem like a very good idea to me.

 

[Vic]

Assuming you are talking about the 4ohms Scout 112 cabs, be careful of that 2ohm load. The Mesa Walkabout documentation is wonderfully obtuse on the 2ohm issue... basically saying it's safe but don't do it! I've read a number of posts where TBers are running their Walkabouts at 2ohms, but it just doesn't seem like a very good idea to me.

+1
I'd say based on the language of the manual that it puts you at risk of thermal shutdown, which, going by murphy's law, will take place right in the middle of the best solo of your life. Plenty of 4 ohm options out there.

However, I wondered about a 3ohm load. Let's say you had the 4 ohm Scout, which is what you used the most, but then for some larger stuff, attached a 8ohm extension to it. The internal speaker is still getting most of the power, but a little extra fortification from an external cab might still make a big diff, and the load level might still be within the truly safe zone. Hmmm...

 

[KJung]

+1
I'd say based on the language of the manual that it puts you at risk of thermal shutdown, which, going by murphy's law, will take place right in the middle of the best solo of your life. Plenty of 4 ohm options out there.

However, I wondered about a 3ohm load. Let's say you had the 4 ohm Scout, which is what you used the most, but then for some larger stuff, attached a 8ohm extension to it. The internal speaker is still getting most of the power, but a little extra fortification from an external cab might still make a big diff, and the load level might still be within the truly safe zone. Hmmm...

That might work fine, although 2.67 is still closer to 2 ohm than 4ohm... so you still might end up with heat problems. The only trouble with that option is that the 8ohm extension will be drawing less watts from the cab than the internal speaker. Might sound OK, might be a little strange depending on the sensitivity of the 8ohm cab.

 

[Hawkeye]

I'll play the role of dissenter in this Scout / Walkabout love fest.

I tried a couple of the Scout Combos a month or so ago (the regular black tolex and a funkadelic purple metallic vinyl covered combo). I used a Precision MIA which I am very familar with and....

I thought that (given the price of that thing $$$$!) it should have sounded a lot better. It struck me as having a sort of BRAHHHH... sound to it, kind of indistinct and lacking punch. Lots of midrange going on but the lows were muddy and had no definition. Sorry, I have read the posts here and evidently others have not had this experience. As for me, I was underwhelmed. YMMV

The Scout combo is good "for its' size" but until the laws of physics are repealed, there is only so much bottom that can come from that combo given its dimensions despite passive radiators and ports or whatever. I thought it was very over-priced for the level of performance you got from it.

My Ampeg SVTIII Pro and Peavey 115 BVX BW could kick its @$$ all over the street for less money with more power, more punch, better definition, you name it.

On the other hand, I played a Big Block 750 thru the Mesa 2x12 cab and..... wow, that's a nice combination. I loved that sound.

 

[BillisCool]

My Ampeg SVTIII Pro and Peavey 115 BVX BW could kick its @$$ all over the street for less money with more power, more punch, better definition, you name it.

See now, you tried the 12" scout?

Maybe I shouldn't get one.

I have the 15" scout and I liked it way better than my IIIpro/410SVT's ass. (more reasonable to gig with/way better tone)

 

[Vic]

That might work fine, although 2.67 is still closer to 2 ohm than 4ohm... so you still might end up with heat problems. The only trouble with that option is that the 8ohm extension will be drawing less watts from the cab than the internal speaker. Might sound OK, might be a little strange depending on the sensitivity of the 8ohm cab.

Yeah, like I said, I know the 12 would still be getting most of the power (2/3) of the power, or looking at it another way, twice the wattage (if it were simply linear, which I bet it's not in reality), but the extra bit of air might still be significant enough to be worth it (depending on the cabs efficiency, of course).

My main thought is, they "mealy mouth" their way around 2ohms, so I was just wondering if 2ohms is really the border, then maybe that extra almost-an-ohm might be safe.

I wouldn't bet a gig on it, but it's an interesting thought...

 

[KJung]

Yeah, like I said, I know the 12 would still be getting most of the power (2/3) of the power, or looking at it another way, twice the wattage (if it were simply linear, which I bet it's not in reality), but the extra bit of air might still be significant enough to be worth it (depending on the cabs efficiency, of course).

My main thought is, they "mealy mouth" their way around 2ohms, so I was just wondering if 2ohms is really the border, then maybe that extra almost-an-ohm might be safe.

I wouldn't bet a gig on it, but it's an interesting thought...

+1