Sparky Mark

Can you remember what the issue was and/or link to the forum you are referencing please? Thanks

I've never heard of this; are you sure your memory is correct? Markbass changed from class AB to class D power amps sections in 2012 but that was an evolution not because of any known issues.

I usually take two

There's definitely a class AB theme to your amp collection.

At 11kg this is likely to have a class AB power amp.

Post a thread in the stuff wanted forum describing what you want, where you can collect it and your budget.

Do you like the HB 115 cab but just want more volume?

This thread is becoming a text book example of design by committee.

I think sliders are good for saving space on control busy front panels. Otherwise, if you're only looking at three, four or perhaps five EQ knobs on a large (I've never seen a micro 100 watt valve head) front panel traditional pots with knobs are more attractive.

From a separate thread where the OP stated that he bought this amplifier second-hand I get the impression it may be as much as 10 years old. I'm not saying that the previous owner knew of a problem but failure after only two gigs is quite "unlucky". Any Markbass LM sized head (LM2,3, 250, Tube, etc) will slot into this combo. The OP might find a newish second-hand one for less than a repair. I'm also not so sure the authorised repair shop will supply this assembly without performing the repair itself.

Totally agree with the 100 watts is 100 watts, whatever the amplifier type. I've read so many threads about 100 watts V4B initially being enough then not quite cutting it live. There's not a single 100 watt amp that would handle my gigs in a not too loud pop/rock covers band. If the relatively clean settings on a V4B don't work for you I doubt any 100 watt valve head would (not sure how Handbox manage to get more clean headroom?) I have tried the 200 watt AD200B which is probably the minimum I'd be comfortable with. Valve watts tend to sound sweeter at the limit but are still only watts. Over the past few decades 500 and 800 watt bass heads seem to have become the norm and if you really are using all that power on your gigs a 100 watt amp (valve or otherwise) isn't going to be enough IMO.

As a total Markbass fan of the past 15 years my main worry with the brand is product support. Markbass has released many more innovative products during this period than any other marque and my concern is that its authorised repair centers are unable to support many/most of them. My solution was to buy backups cheaply second-hand, but there is a limit to that strategy.

Me too. Here's my 410. No comb filtering issues that I'm aware of and is in two cabs for improved portability.

I'm using the compressor relatively lightly to just smooth and fatten the clean setting on the VT Bass. The HPF is set at 35Hz. I had read some threads on the placement of HPF and compressor but there didn't seem to be a consensus; much like this thread. I think for my moderate settings there may not be an appreciable difference however I order them but I really appreciate all the advice given above.

And significant low cut too.

Is there the possibility that effects can add back in the sub frequencies the HPF is designed to eliminate?