Mesa Boogie Walkabout Mega-thread Part 10

[sratas]

Ummmm....I may add some details about the fan mod I made on my WA.

The airflow, with the stock fan, is inside the amp from the outside back, then the air goes out via the front and side holes. The side holes carry at least as much air as the front ones, I think a greater amount.

When I swapped the loud AND efficient Sunon fan installing the Noctua NF 8, I used the plastic spacers that kept the Sunon distant from the inside back of the amp. They were quite long. I think this way part of the air moved by the fan was actually a recycled warm air because there was enough room for the air to be sucked from the inside of the amp instead than from the vent holes in the back. Anyway, the output airflow was massive and it obviously worked fine.

When I put the Noctua in, using those spacers, and switched the amp on, I immediately noticed two things, the absolute silent operation and the diminished airflow from the output holes, roughly halved....not so good.

So I opened the amp again, removed the plastic spacers and placed the fan directly on the chassis, with the idea of minimizing lateral air intake and favouring air intake from the outside, fresh air only. In my thought, this move should produce two consequencies, collecting fresh air from outside mainly and straightening the airflow trough the amp, air in from the outside back, cooling, air out from the front and side holes.

There was an unexpected but desirable effect, the airflow coming out of the amp increased sensibly, and the noise too, and I attribute this behaviour to the absence of that spacers and the straightforward airflow from the back holes...the added noise was attributed to increased vibration transmission to the amp chasis.

I think this way it may even work. Let's see....

Agedhorse, what do you think about these empirical observations?

 

[Fekwood]

Thanks for the replies Earl and sratas, it's appreciated!

I too suspect that the replacement fan was installed backwards. Just to be clear, here's a pic of the current installation. The arrow indicates air flow.

Also, while we're discussing the fan, should the red + positive lead, from the the Silenx EFX-08-15 fan, be soldered to the resistor or directly to the board? @agedhorse

Thanks in advance for any replies!

 

[sratas]

Thanks for the replies Earl and sratas, it's appreciated!

I too suspect that the replacement fan was installed backwards. Just to be clear, here's a pic of the current installation. The arrow indicates air flow.
View attachment 1001616

Also, while we're discussing the fan, should the red + positive lead, from the the Silenx EFX-08-15 fan, be soldered to the resistor or directly to the board? @agedhorse
View attachment 1001632

Thanks in advance for any replies!

at least the new fan is mounted without extra spacing, just like mine!

maybe you could rotate the fan, to allow for correct airflow...

in all honesty, I didn't test my WA under challenging conditions, I expect to do it in a few months.

I suspect my Wa will act just fine.

 

[agedhorse]

Ummmm....I may add some details about the fan mod I made on my WA.

The airflow, with the stock fan, is inside the amp from the outside back, then the air goes out via the front and side holes. The side holes carry at least as much air as the front ones, I think a greater amount.

When I swapped the loud AND efficient Sunon fan installing the Noctua NF 8, I used the plastic spacers that kept the Sunon distant from the inside back of the amp. They were quite long. I think this way part of the air moved by the fan was actually a recycled warm air because there was enough room for the air to be sucked from the inside of the amp instead than from the vent holes in the back. Anyway, the output airflow was massive and it obviously worked fine.

When I put the Noctua in, using those spacers, and switched the amp on, I immediately noticed two things, the absolute silent operation and the diminished airflow from the output holes, roughly halved....not so good.

So I opened the amp again, removed the plastic spacers and placed the fan directly on the chassis, with the idea of minimizing lateral air intake and favouring air intake from the outside, fresh air only. In my thought, this move should produce two consequencies, collecting fresh air from outside mainly and straightening the airflow trough the amp, air in from the outside back, cooling, air out from the front and side holes.

There was an unexpected but desirable effect, the airflow coming out of the amp increased sensibly, and the noise too, and I attribute this behaviour to the absence of that spacers and the straightforward airflow from the back holes...the added noise was attributed to increased vibration transmission to the amp chasis.

I think this way it may even work. Let's see....

Agedhorse, what do you think about these empirical observations?

Yes these are typical. If going to the quiet fan, I strongly recommend against any 2ohm operation.

 

[agedhorse]

I can't offer advice on a modification that I have not investigated. Way too many variables that can bite you in the butt.

Airflow is in from the back and out the top/side vents. This is important.

The spacers are for anti-shear purposes andcreduce noise significantly.

Why would somebody who does not understand how the amp is cooled change the air flow and direction? Kind of mind blowing IMO

 

[Bugeyed Earl]

Thanks for the replies Earl and sratas, it's appreciated!

I too suspect that the replacement fan was installed backwards. Just to be clear, here's a pic of the current installation. The arrow indicates air flow.
View attachment 1001616

Also, while we're discussing the fan, should the red + positive lead, from the the Silenx EFX-08-15 fan, be soldered to the resistor or directly to the board? @agedhorse
View attachment 1001632

Thanks in advance for any replies!

Hmm, the resistor doesn't look right to me, though mine is an older, silver-faced version, so what do I know?

Judging by that big wad of lavender electrical tape, your amp has had some sketchy work done, might be a good idea to get it to Mesa for a checkup.

 

[HeyyyyyJoe]

Anyone recommend a warm growls preamp tube to put in V1? Previous owner put TAD 12AX7s in there.

 

[agedhorse]

Anyone recommend a warm growls preamp tube to put in V1? Previous owner put TAD 12AX7s in there.

You might try a 12AT7 or 12AU7 and see what you think. It changes the articulation a bit, some folks really like the change, others not so much. The difference is pretty noticeable.

 

[HeyyyyyJoe]

You might try a 12AT7 or 12AU7 and see what you think. It changes the articulation a bit, some folks really like the change, others not so much. The difference is pretty noticeable.

Thanks! Any brand you recommend?

 

[agedhorse]

None specifically, the main difference is the whole spec. family curves are different more than a particular brand or "style"

 

[gillento]

I tried different ones, even the AT7, but the TungSol Gold AX7 works best for me. It is a bit fuller sounding than other tubes I tried (JJ, Gold Lion, TAD both AT7 and AX7)

 

[sratas]

I went for a big tube rolling session when I aquired the WA, and, being a studio guy, I recorded every tube playing the same riff with same eq and using variations of gain, from clean to growl to OD. Used contemporary tubes as well as vintage used ones. Some brands were sylvania, national, philips, GT, JJ, Tungsol, mesa stock, various Sovteks. All 12ax7, some of them maybe 30-40 years old. Tried swapping them in V1 and V2.

What I have understood is:

- there were audible differencies, slight ones, probably missed in many real life situation, except for a single brand...

- speaking of minimal differences, the best for a warm, thick, saturated tone maxing the gain were the Sylvanias. Lowering the gain yelded the biggest warmest tone of the bunch, maybe a tad dark and bassy for my tastes

- for a gainy open tone Sovtek LPS, aggressive, on par with old National

- as for other applications, for example guitar amps, the most balanced neutral
and anonimous sounding was the JJ. I can see why it is widely preferred for bass amps and for reverb or positions other than V1

- mesa stock, named Russian II, were really good sounding, albeit with a somewhat cloudy midrange, but this is quite common in other contemporary tubes as well

- for my tastes, the best proved to be the Tungsol contemporary 12AX7. This tube has all, fantastic clean tone, very open, with a tighter sub bass, detailed precise midrange reproduction, and a sweet high end that projects beyond others, but it doesn't sound plain or polite, it imparts a clear distinctive character to the circuit. You may like it or not. I love it. Bring up the gain and it pushes hard keeping great articulation. Best tone with flats, the amp looses some wooly and gains evething else. Using a barefaced big baby 2 I found myself free of increasing the bass knob in some situations, with other tubes this would likely result in a mushy fest and maybe speaker fatigue at best.

As always, IMO

P.S. Planning to try a quality 12AT7 in V1 as Agedhorse suggested, when I happen to buy one

 

[UpwardGroove]

I went for a big tube rolling session when I aquired the WA, and, being a studio guy, I recorded every tube playing the same riff with same eq and using variations of gain, from clean to growl to OD. Used contemporary tubes as well as vintage used ones. Some brands were sylvania, national, philips, GT, JJ, Tungsol, mesa stock, various Sovteks. All 12ax7, some of them maybe 30-40 years old. Tried swapping them in V1 and V2.

What I have understood is:

- there were audible differencies, slight ones, probably missed in many real life situation, except for a single brand...

- speaking of minimal differences, the best for a warm, thick, saturated tone maxing the gain were the Sylvanias. Lowering the gain yelded the biggest warmest tone of the bunch, maybe a tad dark and bassy for my tastes

- for a gainy open tone Sovtek LPS, aggressive, on par with old National

- as for other applications, for example guitar amps, the most balanced neutral
and anonimous sounding was the JJ. I can see why it is widely preferred for bass amps and for reverb or positions other than V1

- mesa stock, named Russian II, were really good sounding, albeit with a somewhat cloudy midrange, but this is quite common in other contemporary tubes as well

- for my tastes, the best proved to be the Tungsol contemporary 12AX7. This tube has all, fantastic clean tone, very open, with a tighter sub bass, detailed precise midrange reproduction, and a sweet high end that projects beyond others, but it doesn't sound plain or polite, it imparts a clear distinctive character to the circuit. You may like it or not. I love it. Bring up the gain and it pushes hard keeping great articulation. Best tone with flats, the amp looses some wooly and gains evething else. Using a barefaced big baby 2 I found myself free of increasing the bass knob in some situations, with other tubes this would likely result in a mushy fest and maybe speaker fatigue at best.

As always, IMO

P.S. Planning to try a quality 12AT7 in V1 as Agedhorse suggested, when I happen to buy one

Are your observations on the Tung-Sol 12AX7 based on V1, V2, or both? I'm sure it's in one of the megathreads, but which position has the greatest effect on tone?

 

[sratas]

Sorry, the only thing I didn't specify.

Ended up with the Tungsols in both positions, V1 and V2.

I tried and recorded many variations in tube position and every combinations between them, for example Tungsol in V1, JJ in V2 etc etc.

Sincerely, the differencies in tone with the various tubes in V2 seemed to be even less evident than those of the V1 position.

So I simply went for a duet of the same brand, but in my opinion the tube in V1 was more important tone-wise. I could be wrong.

 

[lomo]

I agree tube rolling in the WA does make a difference, but a very small one I'd only obsess over if I was making a meticulous recording (which I never do).
I currently have stock Mesa's in my combo and a JJ and old Raytheon in the separate head . It's all good, all the time

 

[HeyyyyyJoe]

Anyone recommend travel bag for the head? Seems the Mesa one is a very tight fit and there was another recommended brand that appears to no longer be sold. Any recommendations?

 

[gillento]

I put mine into a Peli Storm iM2400 case.

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[tombowlus]

Anyone recommend a warm growls preamp tube to put in V1? Previous owner put TAD 12AX7s in there.

Back when I did some tube rolling in my WalkAbout, the warmest, growliest tube I tried was as NOS Mullard 12AT7/CV4024.

 

[EastCoastThump]

Anyone recommend travel bag for the head? Seems the Mesa one is a very tight fit and there was another recommended brand that appears to no longer be sold. Any recommendations?

As insurance against distant parking and lousy weather, I strongly prefer a one-trip load-in for casuals. With that goal, used outside of its marsupial WA cab, the head's handiest in a 2-space rackbag with a zippered top pocket. (I bought the Walkabout rack ears on TB, but you could make your own or have a local machine shop whip up a pair.)

• Ample protection when I'm loading my own gear
  
• No empty bag to stow after my stage rig is set up
  
• The bag has a strap (use as a shoulder strap when one-tripping w/ smaller cab and instrument gigbag, or wrap around the handle of a folding hand cart to keep bag secure when carted atop larger speaker cab)
• Zippered pocket on rackbag stows cables, DI, compact bass stand, extension cord, etc

 

[lomo]

Anyone recommend travel bag for the head? Seems the Mesa one is a very tight fit and there was another recommended brand that appears to no longer be sold. Any recommendations?

I use a Mu-Friend Gig Skins mixer bag-medium. Great size, fit, finish and functionality.