Replacing head in Markbass CMD 121P

[Nebadon2000]

I have a CMD 121P [+NY121] and would like to put LM Vintage D2 in it.
This way don't have to sell CMD 121P and buy both head and another NY 121 [Also get benefit of backup amp]

The LMV D2 is same size as combo head[aka LM III]

Also does anyone know if you can remove small side tops on combo head with holes for screws [to hold head in and place] and put them on LMV D2; then use LMV D2 top on combo head or are modifications needed to hold LMV in combo and make new top for combo head.

 

 

[Dan Dare]

As I understand it, the amp in MB12 combos is pretty much identical to the Little Mark head. The spec's are the same. Given that the combo will drive an additional cab', why bother replacing it? 

[Nebadon2000]

4 hours ago, Dan Dare said:

As I understand it, the amp in MB12 combos is pretty much identical to the Little Mark head. The spec's are the same. Given that the combo will drive an additional cab', why bother replacing it? 

I am replacing with Little Mark Vintage D2 has tube preamp, footswitchable mute, EQ and boost, parametric mid controls; also is Gold line series build 

Edited July 17, 2021 by Nebadon2000
added info

[dirtyharry]

I don't know the LMV but the Little Mark  III fits perfectly in my CMD102. 

To secure the head I glued 4 small rubber squares just to apply pressure (I did it after a few gigs, it's not a problem at all). If you looking for perfection then you need to drill 4 holes for the combo's top screws, it's a simple job as you have the old head to use as a template. 

[Downunderwonder]

Be very careful about the replacement amp getting the exact airflow as designed. There's going to be special measures to take away heat from tubes as well as the power amp. It won't be the same inside by a long shot.

[yorks5stringer]

When I had a Ninja 250 210 combo I swapped out the head from my CMD121P. The fit was identical although I had to reconfigure the mountings slightly rather than drill new holes. I seem to remember I swapped over the top plate of the amps too. However as Downunder says, it may be different if there is a tube in there, mine were both solid state and the fan location was identical.

[Phil Starr]

I have the MB Tube 500, the 'tube' inside is a miniature tube soldered directly into the circuit board, there doesn't seem to be any special heatsinking or dispersal measures employed other than the normal fan so I suspect there isn't a lot of heat produced by the tube.. I haven't had the chance to compare it directly with the LMIII though so there may be differences I'm unaware of.  You'll have the chance to see if there are any practical modifications when you take the old amp out.

Obviously if there are any vents in the casings they need to be unobstructed when fitted in your combo, so if you find any extra venting in the case you will need to ensure airflow through them. I suspect you won't. Why not contact Mark Bass and ask them?

 

Edited July 19, 2021 by Phil Starr

[Nebadon2000]

48 minutes ago, Phil Starr said:

I have the MB Tube 500, the 'tube' inside is a miniature tube soldered directly into the circuit board, there doesn't seem to be any special heatsinking or dispersal measures employed other than the normal fan so I suspect there isn't a lot of heat produced by the tube.. I haven't had the chance to compare it directly with the LMIII though so there may be differences I'm unaware of.  You'll have the chance to see if there are any practical modifications when you take the old amp out.

Obviously if there are any vents in the casings they need to be unobstructed when fitted in your combo, so if you find any extra venting in the case you will need to ensure airflow through them. I suspect you won't. Why not contact Mark Bass and ask them?

 

The vents and fan locations are the same for LMV D2 and Combo Head in amp. Markbass public policy on replacing combo head with different model is 'Don't Recommend" Most likely knowing things may go sideways with DIY'ers

[Phil Starr]

3 hours ago, Nebadon2000 said:

The vents and fan locations are the same for LMV D2 and Combo Head in amp. Markbass public policy on replacing combo head with different model is 'Don't Recommend" Most likely knowing things may go sideways with DIY'ers

Yeah Markbass aren't very supportive for users in contrast with Ashdown for example. My Tube needs a repair (I dropped it so not their fault) and they aren't forthcoming with a schematic, extracting any information from them is like pulling teeth.