Can one use 2x 1x12 Thiele with a MKIII Combo

[al3d]

I found a deal and bought 2, 2x12 thiele this week, guy wanted to sell them togheter. i see the MKIII as 2x4ohm and 1x8ohm output jacks. Can i use both Thiele and still keep the combo's speaker pluged-in?..or do i risk a tranfromer meltdown?

Any suggestions welcome. i'de love to be able to keep both..looks so damn good..hehehe

Thanks.

[/list]

 

[DougM_TX]

Sheesh, I am very seriously over come with ENVY.

Very nice.

 

[AustinK]

With the amp as is you can't run all of the speakers. That would make a 8/3 ohm load assuming each speaker cab is rated at 8 ohms. With that low of a load it would draw too much current and probably fry your ot.

 

[al3d]

is there any sort of mods i can do to the cabs?...a parallelle port maybe?

 

[ketiov]

Dunno about the Mark III, but the Mark IV's 4 OHM jacks are parallel, meaning if you plug in two 8 OHM cabinets into those the resistance is actually 4 OHMs. Then one speaker can be plugged into the 8 OHM jack as the third speaker.

I am not sure about the Mark III being the same though.

 

[phyrexia]

Now, I have never done this myself, but Boogiebabies claims you can run the combo speaker out of the 8 Ohm Jack, and two 8 ohm Extension cabs out of the two 4 ohm Jacks. It is the same as running an 8 ohm cab into the four ohm output, as far as the amp is concerned.

 

[sfarnell]

I'd use only one extension cab if I were you. Not because using three will fry your transformer, but because the sound is too diffuse using the three jacks. Using one or two, at the most, is much more focused. I found that a 4ohm cab with a Boogie is the ticket. So, I'd get a junction box from Mesa and run two cabs in parallel and then into the 4ohm jack. Don't bother using the speaker in the combo. It won't sound as good as the others anyway. Just my opinion of course.

 

[al3d]

i wanted to ask Mesa directly..but no emails on their site..weird

 

[MrMarkIII]

All three jacks are parallel. Connecting an 8 ohm load to each jack results in a total load of 2.67 ohms.
Many Mesa owner's manuals (i.e., Lonestar) have schematics for speaker connections in the back pages. Downloadable from Mesa's website.

Here's a calculator for speaker impedance matching:

http://colomar.com/Shavano/impedance_proc.php

Values entered horizontally are for series connections.
Parallel connections are entered vertically.
Be sure to show all your work. This will be on the final.

 

[al3d]

All three jacks are parallel. Connecting an 8 ohm load to each jack results in a total load of 2.67 ohms.
Many Mesa owner's manuals (i.e., Lonestar) have schematics for speaker connections in the back pages. Downloadable from Mesa's website.

Here's a calculator for speaker impedance matching:

http://colomar.com/Shavano/impedance_proc.php

Values entered horizontally are for series connections.
Parallel connections are entered vertically.
Be sure to show all your work. This will be on the final.

so...basicaly i can't use all 3 speakers?

 

[sbalderrama]

All three jacks are parallel. Connecting an 8 ohm load to each jack results in a total load of 2.67 ohms.

I don't think thats actually true. I think the 4 ohms are in parallel and taken off a 4 ohm tab on the OT, while the 8 ohm jack is taken off it's own 8 ohm tab on the OT.

 

[AustinK]

i wanted to ask Mesa directly..but no emails on their site..weird

GO TO THE CONTACT PAGE AND THE BOLD PRINT THAT SAYS MESA USA IS CLICKABLE AND IT IS A EMAIL. Oops hap caps lock on.

 

[sbalderrama]

If you look at the Lonestar manual ( get from the Mesa website) in the section dealing with impedences and mismatches for speakers, it shows that to use 3 8 ohm speakers you need to put two of the cabs in series with a series box to make them a 16 ohm load. You then plug the 16 ohm load into the 8 ohm jack, and plug the remaining 8 ohm cab in one of the 4 ohm jacks. Its diagram #10 in the speaker section. You will probably have to build the series box yourself or have someone do it for you, as I've never seen one for sale anywhere. I'm presuming the same technique would work with the Mark, but asking Mesa is the safe bet.

 

[MrMarkIII]

All three jacks are parallel. Connecting an 8 ohm load to each jack results in a total load of 2.67 ohms.

I don't think thats actually true. I think the 4 ohms are in parallel and taken off a 4 ohm tab on the OT, while the 8 ohm jack is taken off it's own 8 ohm tab on the OT.

As Ed McMahon used to say: "You are correct, sir!"
There's two taps off the transformer: one 8 ohm, and a parallel 2 x 4 ohm tap.
I'd guess the bottom line would be, don't go below 2 ohms.

 

[AustinK]

ok if this is true can i run 3 half back 4x12 simultaniously?

 

[MrMarkIII]

If they're all eight ohm cabs, yes.
Power tubes will wear out faster, and the sound will be thinner. But that should be compensated for by twelve 12' speakers!
Where is the drummer gonna set up?

 

[AustinK]

Where is the drummer gonna set up?

Who cares? :lol:

 

[Zorshelter]

sorry to hijack a bit but I have a Mark IV and 2 thieles, I was wondering how do I have to hook them up, I'd like to know in which jack (8 ohms or 4 ohms) do I have to plug the thieles when using the paralled out on the thiele


http://www.mesaboogie.com/Product_Info/Guitar%20Cabinets/1x12+2x12-JackplateLG.htm


Thank you

 

[devilrob1979]

Dude, your question was already answered in the post about the series box. If you're talking about 2 thieles with a head or without the third speaker then use either of the 2 4 ohm jacks with the thieles daisy-chained or you could use a single cord to each cab if they don't have a parallel out. They're both coming off of the same 4 ohm tap on the OT so it really doesn't matter. 2 8 ohm Thieles equals a 4 ohm load on the OT.

 

[Zorshelter]

Thank you, I'm gonna try to find the post you mentioned