4x12 AND 2x12

[justplay]

I've seen this question posted here, but want to know the specifics, regarding the Marshall cab that I can borrow.

I have a Mark V head and also a recto 2x12 horizontal cab.
I'm gonna borrow a Marshall 4x12 to augment my setup for a particular performance outside.

Here's the specs of the JCM 900 lead cab. How do you recommend the hook up? Obviously the Marshall cab will be ran in mono....

So, if I had to try and answer my own question, if I daisy chain ( since the speaker inputs on the mesa head are parallel, I should daisy chain the cabs and run em into the 4 ohm output?

Specs:
Speaker Type: Celestion G12T-75W
Speaker Configuration: 4 x12
Power (RMS): 280W
Selectable Mono/Stereo: Yes
Impedance Stereo/Mono: 8 ohm, 16/4 ohm
30"W x 32-3/4"H x 14-1/4"D
82 lbs.

 

[BrownieD2W]

I asked a very similar question recently and Bandit's info was plenty enough to answer my concerns. I hope this helps.

"If you had two 16 ohm cabs, you can run both using the two 8 ohm output jacks. Not sure if there were changes over the years but my amp has two 8 ohm jacks and two 4 ohm jacks. Since each pair of jacks (one pair of 8, and one pair of 4) are live and always wired to the OT as it has two taps, one for 8 and the other for the 4. Using both 16 ohm loads plugged into both 8 ohm jacks will run the cabs in parallel resulting in a load impedance of 8 ohms.

Same would apply with two 8 ohm cabs, but you would use the two 4 ohm jacks.

Safe miss match would be one 16 ohm cab in one of the 8 ohm jacks, and one 8 ohm cab in one of the 4 ohm jacks.

I would not run two 8 ohm loads using both 8 ohm jacks as they are connected in parallel (internal) as the resulting load would be 4 ohms.

The manual pictograms for the speaker connections is too generic. Most Mesa Boogies will have one 8 ohm, one 16ohm (not on all models) and two 4 ohm jacks. Since the diagrams are generic (one serves all but not models specific) they do not address amplifiers that offer two 8 ohm jacks and two 4 ohm jacks as is the case with the full size Mark V. The diagram showing two 16 ohm loads connected to a parallel box then plugged into the 8 ohm jack would be the excact same thing connecting both 16 ohm cabs into each 8 ohm jack. Load box not required." -Bandit2013

 

[bandit2013]

If the Marshall cab is 16ohms (assuming 1960A or something similar) and since your Mesa 2x12 cab is 8 (assuming it is a mesa cab)

Safe mismatch is 16ohm 4x12cab in the 8 ohm output jack, 8 ohm 2x12cab in the 4 ohm jack.
Note that this is covered in the user manual. If you do not have one, download from Mesa as it is a useful tool to have in case you need to reference something... On page 56 figure 7 shows how to connect 8 ohm with a 16ohm in the general pictograms. Note that this would also apply if your amp had a 16 ohm output jack.... I just looked up the manual, it appears to be amended again. I never noticed the section how to compare to a Mark IIC+ or Mark IV to the Mark V before.

http://mesaboogie.com/media/User%20Manuals/070425-MkV_160928.pdf

I have done this with an Egnator 412 cab that is 16ohm total load with all 4 speakers in use (speakers look similar to the Seventy 80 but are custom for Egnator, Celestion Elite 75W 16ohm speakers, also have a huge dust cap on the cone which makes it look like it has a 2 inch voice coil, most likely has standard voice coil. Smallest magnets I have seen on a speaker but they do work and do not sound all that bad. For the 8ohm load I had a 1x12 cab with an EV speaker. Take a guess which speaker was dominant..... the single EV. I have also tried it with my Mark V combo, not bad. I actually have better performance with two 8 ohm cabs connected in both 4 ohm jacks.

If you could borrow a Mesa OS Recto 412, you probably would not want to give it back..... And if you could borrow two OS Recto 412, you would definitely pretend that you do not have them and keep them as long as you can..... Mark V though two 412 cabs is Nirvana. :twisted: Note that an 8 ohm load thought he 4ohm output jack will have a different sound to it (some top end frequencies will be reduced). 8 ohm load on the 8 ohm jack will be much brighter.
16 ohms on the 8 ohm jack seemed to loose something, less bass? it has been a while since I hooked up the 16 ohm cab to anything as I did not care much for it. It actually sounded okay thought JP-2C but weak with the Roadster as both of those amps have a single 16ohm tap on the back panel.
It all becomes subjective on how you perceive it sounds. Also the performance of you amp does make a difference too as well as type of speakers in the cab. The Mark V does tend to be a bit on the bright side (at least mine is)