Sparky Mark

I've lost track of where this thread has wandered but returning to the original question if I was trying to emulate Ampeg-like tones with another amp I would consider the Tech 21 VT bass or one of Ampeg's own DI/pre amp pedals as the best way to go. If you are trying to add a valvey character (not necessarily Ampeg like) to your EA head then the Markbass compressore is one of the best pedal valve compressors that does add a nice sheen to the tone. The VT bass is a different animal to either the Paradriver or BDDI because it is designed specifically to emulate Ampeg tones.

Google is your friend. Just search for MOSFET, class D, class AB, amplifier topology. Basschat and Talkbass has loads of great info on all.

I think you are confusing MOSFET with class AB. MOSFET is a type of transistor that can be used in the class D or AB output stage of amplifiers. The important thing is whether it's a class D or AB; class D being much more efficient than AB reducing the physical size of heatsinks, fans and other output components. Even then a class AB doesn't have to be heavy if it uses a switch mode power supply in the output stage like the Markbass LM2.

The Markbass compressore adds a nice amount of warmth and can be as subtle as you like. I like the VT bass pedal but it changes the overall tone much more than the Compressore. The downside of the Compressore is the 12ax7 valve needs a 12v supply whereas the VT is fine running from a PP3.

I couldn't remember quite how it'd tested but 800 watts wouldn't surprise me.

For £220 new or thereabouts I doubt that there's better value out there. I believe it's a genuine 500 watt RMS head (maybe a smidge more) rather than the advertised 2000 watts which is plenty for almost any reasonable gig. If i didn't already have a dozen or so amps I'd be tempted.

I cannot believe that a single 10 cab requires a 300 watt amp? I bet the GK MB200 would be a good partner or a Nano 300 if you fancy Markbass.

The pre amp controls are very different; the mosfet offering the Ampeg style ultra hi and lo as well as five frequency bands for the mid range EQ. Personally I would favour the mosfet feature set.

The tube and mosfet versions are based (copies of) on very different amps. I believe the tube is based on the GB Streamliner and the mosfet has very similar features to Ampeg heads. Therefore I wouldn't expect a review of the tube version to give much indication of the mosfet other than they probably share the same class D power section.

That was a great comparison video with great playing (I particularly like watching those who can use a pick well; I'm still learning after 40 years of finger style!) but I suspect the brightness of the 77 is more to do with the pickup and electronics with perhaps some ash body (probably the heaviest) influence than just the maple board. Just imagine the uproar if the video was trying to suggest heavy basses sounded brighter!

I usually only gig with a single bass so once the amp is set I don't need to adjust other than for volume or room effects. It's interesting that you comment earlier that this is the only head where you have to make major (other than input level?) adjustments between your pb and sr basses. I would see this as an indication that the ABM is giving a more accurate representation of both basses rather than imposing the amps sound. The one control that really needs to be set correctly is the pre shape button which I have off (pushed in).

Have you been able to use it with a band yet? I think this head really shows its strengths in the mix and can sound just average in isolation.

That's interesting and begs the question of what you don't like about it?

£479 for a genuine 600 watt RMS class AB power amp with footswitchable 12ax7 and solid state blendable pre amp, 9 band EQ with mid pre shape, variable compressor and octave down, mute switch plus more is a fantastic deal for the best to date ABM. The only issue with all the above is that to get your tone (which almost certainly is in there) with ABM heads requires spending time learning how all the features work and interact with each other. Because I own lightweight amps that I play basically flat ( and I'm lazy) my ABM600 hasn't made it to a gig yet but at rehearsals it has demonstrated to me its immense power and flexibility. If I could only afford one amp I would be happy if it was an ABM600 evo iv; I'd just have to pull my socks up and learn how to use it properly.

If you haven't got one, download the ABM user instructions which gives full details of what the compressor is doing and how it is dependent on setting the input levels optimally.

It's most likely got the mini tube pre (not a 12ax7) as per the Momark and LM tube. The graphic looks to be from the Momark range too. The power section is per the Ninja head. It'll be in Markbass yellow too I reckon although the colour in the photo looks darker. Looks good to me but £800ish for far east product could be too high.