Mesa Walkabout Megathread!

[Notfondofrotos]

Hi Guys - Sorry to jump in on this thread but what's the arithmetic which gives 4 ohm (scout cab) + 8 ohm (extension cab) = 2,67 ohms? More like 6 and a bit ohms - You'll lose power.

I've got one of these Walkabout 12 combos I love it - when it works. I have just bought a Markbass R500 as a back up.

 

[mike_v_s]

Hi Guys - Sorry to jump in on this thread but what's the arithmetic which gives 4 ohm (scout cab) + 8 ohm (extension cab) = 2,67 ohms? More like 6 and a bit ohms - You'll lose power.

I've got one of these Walkabout 12 combos I love it - when it works. I have just bought a Markbass R500 as a back up.

Taken from the Amp FAQ:

"Total impedance = 1/(1/a + 1/b + 1/c ... + 1/n).

When all the cabinets or speakers are the same impedance, all you have to do is add up the # of speakers and divide the resultant number into the # of ohms of each speaker. For example, three 16 ohm speakers wired in parallel in a cabinet = 3/16, or 5.333333.… ohms. That’s how they get those 5.3 ohm 3x10s btw! (The 2x10 cabinet with 4 ohm speakers mentioned above wired in parallel would have a net impedance of 2 ohms). When the impedance of the different cabinets or speakers is different, you have to use the full formula. With a 4 ohm cabinet and an 8 ohm cabinet run in parallel the formula is 1/(¼+1/8). You can’t add ¼ to 1/8 without having the same denominator (I told you this was gonna sound like school), so you have to reduce ¼ to 2/8 so they match. Then adding 2/8 to 1/8 gives you 3/8, dividing 8 by 3 gives you 2.67. So, hooking up an 8 ohm cabinet and a 4 ohm cabinet in parallel to your amp gives the amp a load of 2.67 ohms to power."

Mike

 

[Notfondofrotos]

Hey Mike - Thanks for putting me straight.

I think my first post was a reflection on my inability to operate the calculator which comes in the Accessories file on my pc rather than anything to do with anything.

1/4 + 1/8 = 0,25 + 0,125 = 0.375 then 1/0.375 = 2.67 of course it does.

 

[BillyB_from_LZ]

For calculating the resistance/impedance of two (and only two) resistances/impedances in parallel, you can use the product of the two quantities divided by the sum of the two quantities.

4 ohms and 8 ohms in parallel = (4 * 8)/(4 + 8) = 32/12 = 2.67

 

[mike_v_s]

Hey Mike - Thanks for putting me straight.

I think my first post was a reflection on my inability to operate the calculator which comes in the Accessories file on my pc rather than anything to do with anything.

1/4 + 1/8 = 0,25 + 0,125 = 0.375 then 1/0.375 = 2.67 of course it does.

No problem. I started to try and type it out and then 'membered the FAQ.

Mike

 

[BillyB_from_LZ]

...
I've got one of these Walkabout 12 combos I love it - when it works. ...

What problems have you had with your Walkabout?

 

[Notfondofrotos]

Intermittent cutting in and out without any warning - happened at our last gig

Contact cleaner on the pots has seemingly fixed this - But the true answer is an amp tech - there don't seem to be too many in the UK with Boogie experience.

I'll try and post more detailed symptoms later..

 

[BillyB_from_LZ]

Intermittent cutting in and out without any warning - happened at our last gig

...

Does your Walkabout have a little switch to bypass the effects loop? If not, you might try using a short instrument cable to jumper it (effects send to effects return (assuming of course that you're not using your effects loop)).

 

[Bassman62]

Intermittent cutting in and out without any warning - happened at our last gig

Contact cleaner on the pots has seemingly fixed this - But the true answer is an amp tech - there don't seem to be too many in the UK with Boogie experience.

I'll try and post more detailed symptoms later..

Any worthwhile electronics engineer should have no problem working on any amp.

 

[Chef]

'zactly

Does your Walkabout have a little switch to bypass the effects loop? If not, you might try using a short instrument cable to jumper it (effects send to effects return (assuming of course that you're not using your effects loop)).

 

[BillyB_from_LZ]

Any worthwhile electronics engineer should have no problem working on any amp.

I'm not sure that I agree with that...and I'm a EE (and have repaired a number of different amps over the years). It takes a particular skill set to troubleshoot and repair equipment. I work with a number of otherwise intelligent book-smart engineers who wouldn't know which end of the soldering iron to grab.

 

[Notfondofrotos]

Any worthwhile electronics engineer should have no problem working on any amp.

and

'zactly

This is true - but as you know there are 'test points' in an electronic circuit without knowledge of the values at these test points, the 'worthwhile electronics engineer' is at a disadvantage to one who has direct experience of Boogie amps and by that I mean the one who has the circuit drawings and test values. The 'worthwhile electronics engineer' will have his 'meter running' when investigating an intermittent fault what's wrong with looking for someone with direct experience?

I don't remember posting that the amp was impossible to fix - period. I am posting about my experience with this Amp. This will be the seven hundreth and something post in this thread and the vast majoritory of posts will quite rightly be positive experiences of a fine Amp, mine went wrong in a gig that's it.

 

[Bassman62]

I'm not sure that I agree with that...and I'm a EE (and have repaired a number of different amps over the years). It takes a particular skill set to troubleshoot and repair equipment. I work with a number of otherwise intelligent book-smart engineers who wouldn't know which end of the soldering iron to grab.

If you'r a repair engineer and you can't diagnose problems then you'r obviously in the wrong trade.

 

[Notfondofrotos]

Thank you Billy B.

 

[Bassman62]

and



This is true - but as you know there are 'test points' in an electronic circuit without knowledge of the values at these test points, the 'worthwhile electronics engineer' is at a disadvantage to one who has direct experience of Boogie amps and by that I mean the one who has the circuit drawings and test values. The 'worthwhile electronics engineer' will have his 'meter running' when investigating an intermittent fault what's wrong with looking for someone with direct experience?

I don't remember posting that the amp was impossible to fix - period. I am posting about my experience with this Amp. This will be the seven hundreth and something post in this thread and the vast majoritory of posts will quite rightly be positive experiences of a fine Amp, mine went wrong in a gig that's it.

I took a Mess combo to a friend of mine, he downloaded the diagrams and carried out several repairs by late afternoon;
having been in the game for many years that is what I expect; nothing less

 

[wateroftyne]

This is a bit naughty, but can I just direct the readers of this fine thread to a Walkabout Scout question I've just posted here... Thanks!

As you were...

 

[Notfondofrotos]

I took a Mess combo to a friend of mine, he downloaded the diagrams and carried out several repairs by late afternoon;
having been in the game for many years that is what I expect; nothing less

Excellent.

 

[lowmid]

Finally recieved mine!

LOVE it, lots of volume, growl and tone!

portability is really nice

Hovewer, I've bought it new and didn't get a recent model... mine has two instrument inputs and no player control network.. What should I do?

Cheers

 

[Chef]

Not worry about it until/if it ever acts up.

 

[62bass]

Finally recieved mine!

LOVE it, lots of volume, growl and tone!

portability is really nice

Hovewer, I've bought it new and didn't get a recent model... mine has two instrument inputs and no player control network.. What should I do?

Cheers

Contact Mesa, explain the situation and they'll do any upgrades needed.