Pros: Featherweight, sounds good, sufficient for any situation.
Cons: Will not sound like Ampeg SVT. Tube voice is a bit hairy.
I admit - I grew old. Old, weak, bold... and that's pretty sad. Today I have less energy than 20 years ago. Despite all this I'm still playing my bass and gigging, and enjoying it. Since 1996 my gigging amp was Fender BXR300. It sounded awesome, it was loud and it could cover any venue. When I was buying it, I remember the salesman saying: "it's a good amp, but it comes without roadies".
BXR300 was a combo with a 15" speaker. It was insanely heavy, and at some point I've taken the amplifier out and built it an additional enclosure, dividing the weight of the speaker and the amplifier. Still it was very heavy. The cabinet design with casters and two handles on each side supposed it should be carried by two humans.
Fender served me right, but several years ago I was packing for a gig and I needed to take it up the stairs from my rehearsal point to my car. And I was alone. For some reason the parking gate was closed (our rehearsal room is at the bottom of an underground parking) and I couldn't get my car close to the door. So I needed to carry the cabinet on my back, up the stairs, just a couple of floors.
When I finished the last step I felt I'm going to die, and that was a bad feeling. My heart was pumping and my head was floating and I was about to throw up. I sat on the ground by my amp, unable to stand, and said to myself: enough! I'm getting myself a lightweight amplifier.
The next day I started searching the internet looking what the market had to offer. Actually, I needed two things: the amp and the cabinet. In this review I will relate only to the amp (head). I was less lucky with the cabinet, and after trying several lightweight models I simply bought a neodymium magnet bass speaker and built an enclosure myself.
I've seen all the videos and read all the reviews I could find and finally decided on Genz Benz Shuttle 6.0. The thing that convinced me was Ed Friedland's video review. He's a great reviewer and a great bassist, and the fact he got Genz Benz for himself after reviewing it meant a lot. You can see that video on youtube.
I've bought Shuttle 6.0 on ebay, without playing it. It may sound stupid, but I live in Jerusalem, Israel, and we don't have everything for sale in our shops.
Since then, I was using Shuttle for all gigs and my Fender rests at the rehearsal point.
Now let's get a little technical for a while.
0. Weight and size:
This is the first thing I've got this amp for, and it is really small and light. 3.75lb is something you can hold in one hand. The footprint is slightly larger than A4. It fits in my handbag; it fits in my bass' gigbag pocket. Unbelievable indeed. The reason for this is Switchmode power supply which eliminates need for a heavy transformer and class D power amp, which is also light and small.
While this is awesome, there's one side effect I was not prepared for. The amplifier is so light it may get knocked down if you pull the cord. Genz Benz have a simple solution for that in their combos, where the head is attached to a speaker cab. However, if you use the head alone or with non-GB speakers, you need to take care of this. Put something heavy on it or use duct tape to keep the head grounded.
The power amp is specified 600W into 4 Ohm load, or 375W into 8 Ohm, which is a lot. Theoretically, with a proper cabinet it will cover any club without any additional amplification. And if you play stadiums they usually have PA, so I'd say it covers every possible situation.
The preamp has all the features and, although it looks coompact and modest, there are plenty of tonal possibilities. First, there's a 12AX7 tube, which gives it a vintage character if desired. We have gain control (tube overdrive), preamp volume and master volume (power amp) knob. These three controls help you dial any volume and fatness combination, from dry and clean to almost muddy tube character, and at any volume, starting at the very low bedroom-friendly level and to, well, to maximum.
The EQ features high, low and parametric mid. It is sufficient to dial anything you want, but there are also three knobs (called "signal shape") which are sort of preset EQ shapes. This allows low boost, hi boost and mid scoop. All three may be used together and they do not neutralize the main EQ. Very flexible.
Now I want to criticize those three little knobs. Although it may look like a good idea, and they actually do what they're supposed to do (boosting, scooping etc.), they affect the voice of the amplifier to the point I avoid using those knobs. In hifi audio there's a statement that says shorter signal path results in a better, pure tone. I totally agree, and while four EQ potentiometers are non bypassable and I don't know if the amp sounds better without the EQ, those three EQ preset knobs are bypassed when not pressed and the amp sounds much better without them. Actually, I may boost lows and highs or scoop mids with the EQ, without touching the knobs. I'd suggest Genz-Benz drop these three knobs, saving costs and keeping it simple.
3. Additional helpful features:
The amp is loaded with all possible features you may need.
Mute knob is something every amplifier must have.
It has balanced out which is awesome because at gigs you're not running into DI and then into your amp, but you simply send that balanced line to the house and do whatever you want with your EQ, muting without asking soundman to turn you down etc.
Tuner out! Aux in! Effect loop! Headphones jack! Everything you may need, even if you don't use them.
I haven't played the amplifier before I've bought it, and the first time I plugged it in I was surprised. Unpleasantly surprised. With all controls set flat the amp sounded very plain, dry and lacking any character. Before too late, I started twisting knobs and pretty soon dialed in a tone I like. I needed to boost gain (tube overdrive) almost to the maximum and I also boosted lows. Lots of meat, you know, is what I like. By the way, my only bass is Fender '62 Jazz reissue from 1995. Passive and very simple.
So, basically I can dial in everything I want. There's always some transparency, unlike many other amps. I'd say it somewhere in Gallien-Krueger ballpark. Nowhere near Ampeg or my beloved Fender. Markbass, for example, sounds fat and ballsy straight with all controls set flat, but on the other hand you cannot get really clean like Shuttle 6.0 can.
I am a little unhappy with the tube sound. I've heard many tube preamps and built several myself, and there are many designs that sound better. It is dead quiet, no unwanted noises or hum, but the character is somewhat hairy. I'd love to hear less fuzz and more fatness, and although it's almost there, I'd play with cathode and anode resistors to see if I can make is sound a little different. Unfortunately, inside there's a SMT (surface mount) circuit board with tiny parts and its not possible for a human with a soldering iron to mod it.
As I've started bringing the amp to all sorts of gigs I started to realize the greatness of this small head. While most of the time I kept pushing bass and gain to the maximum, sometimes I was playing venues that were terrible - wet and insanely boomy. So I was turning my amp flat and is was the most proper tone for those places. If I've had any other amp I would probably sound muddy, but with Shuttle 6.0 I could fight those conditions and still cut through the mix.
When playing a retro-style band with female singer I was turning preamp gain to the absolute maximum and master volume close to zero and running straight to the amp with no efforts. This produced fat and compressed tone, a lot like some Gibson EB-0 bass, but with Fender Jazz.
With ethnic project where I play with drums and duduk I kept bass around 11 o'clock and tube gain close to the minimum. This gave me clean and articulated tone, with almost piezo-like clarity. For beefing up my sound I played with BASS CS-2 compressor.
Etc, etc. I mean, it is flexible, extremely flexible. Metal to jazz, world to dubstep. You need to make adjustments, and I haven't been looking for a sweet spot - there are many possibilities and they all sound good and different.
There are several weak points I'd like to emphasize.
1. I've already mentioned the weight problem: it's too light so it may fall if you move around and pull your cord.
2. It's durable, it's metal, but still you can break it. I've arranged some sort of padded bag for it, but still the knobs of the front panel are sticking out and they get knocked sometimes. Master volume knob already makes annoying noises when I turn it, and damn, these noises are 600W loud!
3. Once upon a time I arrived to audition for a backup band for some singer. Gig bag with bass on my back, lightweight 15" speaker in one hand and a handbag with the other stuff, including the Shuttle head. No sweat. When I unpacked and started plugging my stuff together I haven't paid attention the volume selector jumped from 230V to 110V (I'm from Israel, remember?). Not only the volume selector jumped, the on/off switch was on. So, when I plugged in the electricity cord, the amp flashed inside and died on my hands at that very moment. Disaster!!! Not only I ruined the audition, I've burned a very nice amplifier. After several attempts to fire it up (no pulse, no breath) I started to look for a fuse, but there was no fuse compartment and the case had a small sticker saying "no serviceable parts inside". I've got home almost in tears, thinking the amplifier is dead.
I usually repair all my stuff myself, so this time I wanted to attempt a repair, although indeed, modern SMT boards are not serviceable. I've opened the amp and - voila! I've found a burned fuse. I've replaced the fuse and it was working like nothing happened. So, there are serviceable parts inside. One is the fuse (5A) and the other is the 12AX7 tube.
So if you take it for a gig you may need a philips screwdriver and a spare fuse.
By the way, the audition ended fine and I've got the job - I've plugged into some portable PA that was there. But it turned out there was a very little money paid and there were way too many rehearsals, so at some point I quit. Which brings another useful feature of Shuttle 6.0 - it predicts the future. It was trying to tell me "don't waste your time, look, I don't want to play this gig" and I wasn't listening.