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Here is my A/B review of Gallien-Krueger’s 3-space giants. In the red corner, we have the reigning champion: the 2001RB. In the blue corner, we have the newcomer and challenger: the Fusion 550. Which works better for me? It wasn’t easy to figure that out!

LET’S GET TECHNICAL

To start, let’s discuss the technical differences between the two heads. I split the specs into two columns. Similar/identical items should be directly across from each other for ease of comparison (i.e., Deep Switch and the 5-String Button, Lo-Mid knob and Lo-Mid knob, etc.).



Right off the bat, we have some differences. The 2001RB’s dual poweramp system provides a massive amount of power, and allows for some unusual cab powering scenarios (up to 4 cabs) in addition to a traditional solo cab or 2-cab stack. But consequently, the 2001RB is also simply massive for a solid-state head - weighing 15 lbs. more and running 2” deeper than the Fusion 550.



GK did away with the clip LED and turned the Pad function into a switch. It also changed the role of the initial gain stage. With the 2001RB, your Input Level setting has an impact on your growl with the Boost stage. With the Fusion, there’s just one stage before the preamp and no Boost stage after. Your growl will depend on that single Gain knob before the preamp, instead of playing with two gain stages (one before and one after the preamp) to achieve your tone. I’ll get into the results of that momentarily.



The 2001RB adds a significant boost to low end with the 5-String button. The Contour and Presence controls offer flexible twists on classic 800RB functions. But with the Fusion, they opted for a simpler approach. The Deep and Bright switches may not have as potentially massive of an impact, but they’re fixed at ideal preset points and centered at similar frequencies. The biggest change, however, is with the Contour feature. The 2001RB is the classic Mark II variation: adjustable mid scooping and bass/treble boosting, with the scooping centered at 500Hz. The Contour on the Fusion is very different – it only scoops mids, and now offers the ability to do so at 800Hz as well. This allows for a different kind of tonal variety with the Contour knob than was available with the 2001RB.



The EQ has seen some minor tweaks. The significant change is with the center frequency and boost/cut range of the Bass knob. I’ve noticed that the Ampeg SVT-CL uses the same center frequency for its Bass knob (40Hz).



The Output stage has been largely simplified in the Fusion 550. With the 2001RB, you have more options for tweaking what frequency range the speakers and tweeters produce. You also have the Boost knob, which technically comes before the output stage, and is central to producing the GK growl. The Tweeter knob controls only the tweeter volume, and the Woofer knob controls only the volume of the speakers. The Fusion opts for a different approach. With the Gain knob taking care of growl and distortion via tubes, the Boost knob has been removed. The new Horn Bi-Amp knob controls the ratio of volume between the tweeters and speakers, so the Master volume now affects both. For non-tweeter action, turn the Horn Bi-Amp knob to zero.



The 2001RB’s second channel is a unique overdrive channel with a 2-band EQ that overlaps the settings shared by both channels. Meanwhile, the Fusion’s second channel is identical to the first one, and the settings are recalled via motorized knobs.



Again we see the complexity and flexibility of the 2001RB. The 2001RB has additional outputs and features to accommodate its twin poweramp arrangement, while the Fusion 550 keeps it simple. The 2001RB also has a remote trigger and master/slave chaining feature which allows multiple 2001RBs to be linked together and turned on/off simultaneously while receiving a signal from just one instrument. Most of us would never need something like that – it’s more of a pro-with-multiple-rigs sort of thing.

THE SOUND (CLEAN)

Now let’s talk about the most important feature of any head: how it sounds. I A/Bed these two heads using the same cabinet (a GK Neo 212), the same effects, and the same bass (an Ernie Ball Music Man Stingray strung with Hybrid Slinkys).

For those who fear that the Fusion may not be very GK-like, don’t worry – it still sounds like a GK head. Only with tubes in it. The simplified features, tube-based circuits, and EQ/voicing tweaks are certainly noticeable in the character of the Fusion’s sound. While it isn’t as punchy as the 2001RB, it makes up for it with a warmer, rounder bottom end and seemingly richer mids. Notes played (especially in the upper frets) have a more tube-like “bloom” to them without losing of the classic GK attack and punch. The simplicity of the head is a blessing in disguise; while I find it just as easy to dial in my usual tones, I’ve also found the shaping functions to be friendlier and more practical in the type of music I play (rock, metal, etc.) than with the controls available in the 2001RB. However, I do think the 2001RB may be more appropriate for the slapper or the clean headroom seeker than the Fusion 550. Additionally, the 2001RB does have a more dramatic potential for deep low end, as it has both the power and controls to pump out lots of it. My bandmates preferred the Fusion for its midrange content and overall tone. Plus, as any GK head does, it shined in the mix with its presence.

THE SOUND (OVERDRIVE)

Great clean tones aren’t usually enough to convince me that my 2001RB is worth replacing, although the Fusion has provided some incentive. The overdriven tones are one of my main concerns as well. The 2001RB has a cool overdriven sound, but it clashes with some active basses; I have to use the pad button with my Stingray or I’ll suffer a huge volume drop and distortion increase on the overdrive channel. With the pad on, the tones are thick, crunchy, and overall aggressive. There is a huge range of gain, too, and it could even pass off well as metal-class distortion. Unfortunately, I’ve felt that the shared controls are a bit restrictive, and the overdrive is on the darker side of tone. Arguably, this was not really a problem with my old Schecter Stiletto basses, but with the Stingray, I thought I could do better.

The Fusion 550 does not disappoint with the overdrive! I was ecstatic to have an entire channel’s worth of controls to play with for my custom overdriven tone. One thing I noticed immediately, however, was the range of gain. The Fusion 550 has a ton of headroom, and the Active/Passive switch simply didn’t let me get any overdrive when set to “Active”. With the switch on “Passive”, however, I can get a good amount of dirt. It can be as smooth or growly or aggressive as I want. Overall, there is nowhere near as much gain as what was possible with the 2001RB, but the flexibility and range of tones meet my needs perfectly. It passed both band muster and my own.

CHANNEL-CHANGING

The motorized knobs on the Fusion are certainly a concern, so I tested the channel switching during our band practice session. The transition does not noticeably impact our playing at all, and the transition itself is pretty smooth and quick. The 2001RB, meanwhile, is instant in terms of channel transition. Overall, I think the motorized knobs and channel changing will not be a burden on me, and it’s always cool to watch.

POWER AND VOLUME

I'm sure a lot of 2001RB owners (and 1001RB-II owners, for that matter) noticed the big difference in power between those heads and the Fusion 550. In our practice session, I never needed to turn up past 9:00. When I did have it at 9:00, my drummer was yelling at me to turn down. The Fusion 550 is LOUD, and I don't think volume is going to be an issue.

Overall, what the power difference may possibly mean is a reduction in headroom at higher volumes (which would impact clarity and low end), and an overall reduction in potential volume. As I mentioned earlier, the 2001RB has the potential for an incredible amount of low end, as long as you have the cabs to handle it. You may have to even cut bass (I know I did!).

However, I'm not worried about it. While I have yet to crank it to see what that will realistically amount to, consider this: In live gigging situations, I never cranked my 2001RB past 11:00, in Bridged Mode (delivering 650W RMS to my cab @ 8Ω), with the Pad button on. I'm currently running the Fusion 550 with the Active/Passive switch set to Passive, and it can deliver about 350W RMS @ 8Ω. So, I'm not worried. If I never had to crank my 2001RB, I won't have to crank my Fusion. And if I ever do... what I'll really need is a second cab.

SUMMARY

The 2001RB has served me well at many gigs, and is by no means a disappointment. It reminds me of why I am a GK fan. But the Fusion 550, despite its simplicity and somewhat different tone than the usual GK head, simply works better for the tone I’m seeking. I will be spending some more time with these two heads to be sure of my choice, but I think I’m going to have to say goodbye to my 2001RB…

Nice!