Used 18w TMB, too middy, where to start...

[Jalfrezi]

So, I picked up a used TMB this week, all seems to work quite well, with a few caveats:

1. Overall too strong mids/low mids, lacks clarity (tried with Strat and LPjr P90). I do like brighter sounds, so this may be subjective, but would like to fix this. Not sure if the mids are too strong, or the treble too weak.
2. MV works on both channels, which I would like to undo, as this seems unnecessary for how I'd like to use the amp. I was planning on an ABY pedal, with clean on channel 1
3. All the tone controls have little impact upon the tone, they do work, but seem limited in their "power" to sculpt the tone. I would like to make them more effective.

The amp seems in good condition, and quite well made (by Eli Abbott in the UK). I have tried swapping out the preamp and power tubes, but this made little difference. I'm running it through a 1x12 with a G12H-30 70th Anniversary speaker

So, where to start? Initially, I thought I would choose a schematic/layout, and check component values, and look for failed resistors/caps. But then I realised there are many variations, so not sure which schematic to use as a base. Overall, I'm a lower/mid gain player, if that helps choosing a design.

Any recommendations? TIA

[JMPGuitars]

Hi, welcome to the site.

One of the largest impacts on tone you'll see in this regard is your speaker choice. I suggest trying other speakers if you have any available. The G12M Greenback is much preferred compared to the G12H. Personally, my favorite is the WGS Blackhawk.

For document reference, I suggest comparing whatever the builder used to the TMB Modern Classic: viewtopic.php?t=25606

18W amps in general are considered bright. It's possible something is wrong if you think it's not articulate enough.

Thanks,
Josh

[Bieworm]

The G12H anniversary is about the worst speaker I ever encountered. In no way anything like the original G12H30 from the olden days. Best new choice is the G12H30 heritage series (UK made)
There is a night and day difference.