Mark IV combo + 2 Mesa 8 ohm cabs ohm load?

[Force]

Can I safely run the internal speaker plus use 2 ext. cabs if the ext. cabs are daisy chained using the parallel out of cab1 to cab2? It seems to me the amp would see a 4 or 6 ohm load overall using the 8 ohm EV internal speaker plugged into one 4 ohm speaker jack, and ext. cab # 1 plugged into the other 4 ohm speaker out jack, if I use the parallel out from cab #1 :arrow: cab #2. (they are both Mesa 8 ohm mono cabs). Is this ohm load safe & a correct mismatch?

 

[MrMarkIII]

You will have three 8 ohm loads in parallel, for a total load of 2.67 ohms. Still safe, but at the margins.
You really should try the two external cabs into each of the four ohm jacks for a total of four ohms, without the internal speaker, at least to see if it sounds better.

 

[Force]

ok. I thought perhaps running two 8 ohm cabs using a parallel out to connect them from one to the other would be the same as using a 4x12, so I could still use my internal EV spkr and end up around 4ohm. No huh? :?

 

[dodger916]

You could also run the two 8 ohm extension cabs in series (via a parallel to series box), resulting in a 16 ohm load. This combined with the 8 ohm combo speaker would result in total load of 5.33 ohms. Plug both loads into the 4 ohm taps and you have a very safe mismatch.

 

[Force]

You could also run the two 8 ohm extension cabs in series (via a parallel to series box), resulting in a 16 ohm load. This combined with the 8 ohm combo speaker would result in total load of 5.33 ohms. Plug both loads into the 4 ohm taps and you have a very safe mismatch.

Hey dodger916, sounds good to me! Say, who can I get a box like that from that you mentioned??

 

[dodger916]

I really don't know. Most of what I've read included people building their own. Maybe Google can help?

 

[zrkrlk]

You could also run the two 8 ohm extension cabs in series (via a parallel to series box), resulting in a 16 ohm load. This combined with the 8 ohm combo speaker would result in total load of 5.33 ohms. Plug both loads into the 4 ohm taps and you have a very safe mismatch.

Hello,

My English is not so well, but i will try...

I have the same problem with my mark IV and my 2x12 cabinet...and i would like to confirm your post. I was building my 2x12 cabinet (2 x celestion vintage 30 8 ohm). I was connect speakers in parallel connection and i was got 4ohm in total for cabinet. I was use one of two 4 ohm jacks for my external 2x12 cab and 8ohm jacks for internal black shadow. I thought that all three connectors are separated and independent in terms of resistance...Now, when i read your post i realize that i was wrong. Total resistance (impedance) in my case was 2,67ohm and this is at margin of my mark IV... I can change connection between my two 12" in ext cab to serial connection and i will get 16ohm for cabinet. In this case i Will plug ext cabinet in one of two 4ohm jacks, but what is happened with my internal black shadow?? Do I have to plug it in 4ohm jacks or can remain in 8ohm jacks? What is difference? All three output jacks on mark IV are in parallel connection?? In general, what the value of resistance is optimal and recommended for Mark IV??
Is there another solution for this situation? Thanks in advance and my apologies for bad English ... Cheers! :?:

 

[Force]

You can purchase a 16 ohm Series box like Dodger talks about from Mesa Boogie directly by calling them at the Mesa Factory in California.

 

[boogiemon]

i seem to remember the manual says you can connect a 16ohm load to the 8ohm jack along with a 8ohm load to one of the 4ohm jacks. If you have two 8 ohm speakers wired in series one could connect these two plus the internal (8ohm) speaker & have three speakers going at once. (safely)

i encourage you to verify this in the manual/docs on the mesa site.

If there are any tech/amp gurus out there, i'd be interested in knowing how many watts the amp is pushing configured like this & what the total ohm load is. Seems complicated to me since as i understand it, the 4 & 8 ohm jacks are run from two different xformer taps.

 

[zrkrlk]

http://www.mesaboogie.com/manuals/LS_Special.pdf

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