Lighter weight amp

You probably have LittleMark? There are other models Markbass makes that have tube in preamp stage, so sound coloration is (arguably) similar to oldschool tube amps.
Also, you could try something before getting new amp, to "warm-up" sound before it gets to your current amp. Sansamp comes to mind, also, if you dig compression, EBS Multicomp has "tube" setting that adds a touch of that tubey sound.

 

Tech 21 VT Bass pedal

 

Good suggestions above. Something else to consider might be the Acme 'Flatwound' 1 x 12 cabinet:
http://www.acmebass.com/#/products
It's 37 pounds, rated for 350 watts, and is designed to have more of a 'vintage' sound than the Acme 3-way cabs.

Oh, and there's also the Mesa Walkabout combo. It's a bit heavier, 50 pounds I think, but has a delicious tubey tone.

 

My PF350 has been great for over two years now.

 

Checkout GKs line of compact lightweight amps, cabs, and combos.

EDIT:

Oops never mind, yeah if you want the Ampeg sound, you really need to get an Ampeg.

 

+1

My 500$ amp sound like a 1500$ amp with the VT, and it gives a lot of the Ampeg sound.

 

Aguilar TH500

 

VT bass pedal !

 

As mentioned on other threads, lightweight is a micro head.
Lightweight cab that can keep up is a Greenboy design

Don't fall for the shoving many speaker drivers in a small cab is more louder. Greenboy designs get the maximun out of the drivers they use.

Many micro's have their own pushing-it tone, but there's nothing wrong with getting your tone from a pedal or modeler. Works on stage and in the studio.

 

Bergantino CN112 cabinet (28 lbs.) and Aguilar TH 500 head (4 lbs.). I don't think you can get any lighter and better sounding than this combination! It won't be cheap, though, but your back will thank u!

 

Genz Benz Sl900 ...

 

'nuther +1

 

Per the above, a VT pedal will take care of your issue. The LMII (which is the model I assume you have) is a fantastic, warm, clean, relatively neutral tone platform. With the VT pedal, which emulates the Ampeg tone, you have everything you need. If you wait another few weeks, the new VT DI will be out, which seems to be an improvement over the original VT model. With any of the VT models, you can bypass the VT pedal for the nice, clean, neutral tone of the LMII, and then kick in some grit and grind when you want it.

The other option (also mentioned above) is the Aguilar TH500, which has a much 'rougher' voice than the LMII/III, and will grunt and growl a bit more on its own. You will give up that warm, pure extended top end and 'flatter' response of the LMII/III, but will gain a baked in tone that might fit your tone goals better (based on your post). It will also hammer a bit harder than the LMII/III.

+1 in that I would personally avoid the small Ampeg class D models.

 

+1 for the Genz Benz Streamliner. The Streamliner paired with a GB NeoX 212t is a perfect match and can get the tone you're after. JMO.