Convert Mark V head to combo question,

[bandit2013]

I will be getting a Roadster Head in a few days. What to do with the Mark V head. Recently I shoehorned in an EVM12L speaker in my Mark IV combo. I was curious as to how the Mark V would sound as a combo with an EV. I was overly impressed in all channels and modes. I must have played for a few hours. It is quite a different experience with an EV in an open back cabinet. Reminds me of the Mark III I once had. I did find a Mark V shell but has MC90 in it, no big deal. My question to those who know for certain: The cabinet looked like a Mark V, included shelf with mushroom bolt, internal plack and such. The only thing I noticed missing were the caster plates on the bottom. Every Mark V combo I have seen had the removable casters. Could this be an copy or did Mesa ever offer the combo without the casters. :?:

 

[bandit2013]

It is no longer a question. I won the bid on ebay for the cabinet. The only thing that was missing was the amp chassis. It is like new as described. I was almost tempted to just install the amp chassis from my head directly into the combo cabinet. However, I had plans to use one of the EVM12L Black Label speakers instead of the MC90.

I had to open the baffle hole up slightly. I used a air powered drum sander as this is more forgiving than an electric drill with the same drum. Not much material removal is required to convert to a front mount cabinet. The EVM fit great, and was inserted into the baffle and secured temporarily with the #8 screws originally used for the MC90. All that was required was to drill the other 4 hole and then drill out the existing holes for a tight fit for #10 screws. Next was a simple modification to the grill frame (relief for the speaker basket on top and bottom). I should have taken pictures of the conversion process but I did not. It took a total time of about 2 hours since my air compressor has a small tank and could not support continuous sanding operation. Modification to the grill frame required a micro router which cut the time down considerably. Since this is the second front mount conversion I have done to a wide body combo, it was easy since I had the tools to complete the task.

My concern was the clearance for the preamp tube retainers as they stick out considerably. Once I mounted the amp chassis, my concern was eliminated. Appears that the preamp tubes sit much closer to the power tubes and preamp tube change will be easy. The Mark IV on the other hand (reason for the original concern) has the preamp tubes much closer to the baffle and the larger basket of the EV was an issue (when it was rear mounted). I may opt for an EV classic over the Black Label. I will have to think it over. I may even consider the Jensen Jet Black Bird (at least I have the WGS Black Hawk which is a copy to experiment with). I also have a Carvin 100W version of a V30 that I pulled from the V3MC in favor of the WGS Black Hawk. I did try the old Mesa MC90 from the Mark IV in there but the voice coil was shot so that never stayed in there. Now that I have a new one, it may work out. Now that I have a few speakers to try out with the Mark V combo, I can hear what works best with it. I believe the WGS will be the winner in the test so I may opt for the Jensen due to its higher power capacity. If and when I decide to change speakers, I can take pictures of the mods necessary for front mounting.

So far it sounds great, will have to try it with the oversized 1x12 extension cab (also has EV black label) Running two 8 ohm speakers in the 4 ohm jacks does seem to alter the tone some what, seems to boost the mids and cut down on brightness. I am not loosing out here as I have two 412 cabinets that I can use with the Mark V combo if I wish. The Roadster essentially took the Mark V's place on top of the oversized Recto slanted Cab (modified with 4 EVM12L Black Label speakers).

The cabinet did not come with caster plates or casters. I was considering ordering them from Mesa, but have changed my mind.

 

[bandit2013]

Placed the converted combo on top of the oversized 1x12 and all was transformed into a 412 sounding arrangement. I would say the EVM12L Black Label stays.

Trick to doing the front mount conversion on the combo, do not use t-nuts. Since I used #10-24 cap screws to secure the speaker to the baffle, the T-nut would require a relatively larger hole which may cause the baffle to split at the speaker opening. Instead I used two washers and a locking nut. One oversized washer to spread the compression load and a smaller one to prevent the curl of the large washer from encroaching the lock nut. I used T-nuts the first time when I converted the Mark IV to front mount and I which I had not done so.

 

[bandit2013]

Here are a few pictures after the head to combo conversion. Note the Roadster that prompted the Mark V head to combo conversion. I could not be happier how it all turned out. I can still use either 412 cabinet with the combo since I repositioned the Mark V between the Roadster and the RA100 rigs.

Before:

After:

Note: I had to modify the 1x12 extension cabinet. When I ordered it, I thought it was ported, it was not. The odd cut in the back panel was to eliminate air vibrations. I had to keep removing material to reduce the buzz. I started out with an oval cut and that just did not work too well. One of the T-nuts is missing due to stripped out threads. The extension cab was a test base for a multitude of different speakers as was the Mark IV. I still have the Mark IV combo, not pictured as it was not in the room the time I took the photos. I did have the EV in the Mark IV but prefer the Fane Studio 12L with that amp.

 

[wgwmesa]

Hey Bandit, do you still have the Mark V head cabinet? Interested in selling it? Assuming it's in decent shape and the price is right, I'd like to buy one. I'm going to go the other direction (I currently have a combo and want to convert it to a head version).


Thanks,

WGW

 

[bandit2013]

I still have it, In good shape too. Still has original reverb tank and cover. Only items missing are the mounting straps and bolts (just reuse the existing from your combo). I will try to take some pictures of it. The only thing missing are the mounting bolts and metal straps but you can use the existing mounting hardware from your combo.

 

[wgwmesa]

Sweet. I'll send you a PM.


Thanks,

WGW