Loud, clean & dirt cheap

[garyfanclub]

Another recommendation (not sure if you're going for combos only) would be any 70s Acoustic Bass head or guitar combo.

I used an Acoustic 140 as a keyboard/guitar amp for a couple years, and while fairly sterile and lacking a mid control, was definitely LOUD and CLEAN through a 4ohm 2x12. The guitar version (the 150) has reverb and tremolo if that's a must for you. There are a couple of each on reverb in the $250-350 range.

Wouldn't recommend either of these for bass, not enough oomph by a long shot.

Looks like there are also the Acoustic 134 and 135, which are combo versions of the 150 with 2x12 and 4x10 configurations. Looks like there are few in the $400 range, good luck with shipping though.

[cestlamort]

I had an acoustic combo (2x10, a 114 model, I think) from around that era and it was pretty great. Or at least a pretty great use of $100 to buy it.

[Sauerkraut]

Another recommendation (not sure if you're going for combos only) would be any 70s Acoustic Bass head or guitar combo.

The OP found what he’s looking for, but keep those recommendations coming. Might help some others. It seems there are quite a few 70s solid state amps that are great if just need a loud, clean, good-sounding amp and don’t want to spend much.

[dinosaurkale->]

pretty much any Polytone amp

[Racing]

You´re in Berlin right?
As in Germany?

In that case if tube amps is your game, pick up one of the higher wattage old butt ugly Hohner MH-series amps. They will give a Fender twin a run for the money any day of the week and this at an absolute fraction of the cost.
Fact is, personal opinion, i cherish the Hohner clean sound more than the Fender. The MH-60 combo can be a bit on the hefty side weight wise but.. for the money (150-250€ maybe) they´d be very very hard to beat.
Built in the -60´s, made in "West Germany".