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A/B REVIEW: GK 2001RB vs. GK Fusion 550

Discussion in 'Amps and Cabs [BG]' started by JanusZarate, Sep 20, 2008.

  1. JanusZarate

    JanusZarate Low End Avenger Gold Supporting Member

    Feb 21, 2006
    Petaluma, CA, USA
    As promised, 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!


    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.).

    [B]2001RB SPECS:                       FUSION 550 SPECS:[/B]
    SS Preamp w/ Boost Circuit          Tube Preamp
    Dual SS Poweramps                   Single SS Poweramp
    540W RMS @ 2Ω Min. (Each)           500W RMS @ 4Ω Min.
    Bridged: 1080W RMS @ 4Ω Min.
    Tweeter Amp: 50W RMS                Tweeter Amp: 50W RMS
    42.5 Lbs.                           27.5 Lbs.
    19” x 5.25” (3 Rack Spaces)         19” x 5.25” (3 Rack Spaces)
    12” Deep                            10” Deep
    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.

    [B]2001RB SPECS:                       FUSION 550 SPECS:[/B]
    Pad Button (-10dB)                  Active/Passive Switch (-10dB)
    Pre-Input Clip LED
    Input Level Knob                    Gain Knob
    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.

    [B]2001RB SPECS:                       FUSION 550 SPECS:[/B]
    5-String Button (+10dB @ 20Hz)      Deep Switch (+4dB @ 30Hz)
    Contour (Flat to +2dB @ 50Hz,       Contour (Flat to -16dB @ 500Hz OR
          -10dB @ 500Hz, +3dB @ 7KHz)         -15dB @ 800Hz)
                                        Frequency Switch (500Hz or 800Hz)
    Presence (Flat to +9dB @ 10KHz)     Bright Switch (+4dB @ 10KHz)
    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.

    [B]2001RB SPECS:                       FUSION 550 SPECS:[/B]
    Bass   ([U]+[/U]10dB @ 60Hz)               Bass   ([U]+[/U]14dB @ 40Hz)
    Lo-Mid (+6dB/-10dB @ 250Hz)         Lo-Mid (+6dB/-9dB @ 250Hz)
    Hi-Mid (+6dB/-10dB @ 1KHz)          Hi-Mid (+5dB/-8dB @ 1KHz)
    Treble ([U]+[/U]14dB @ 7KHz)               Treble (+10dB/-19dB @ 7KHz)
    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).

    [B]2001RB SPECS:                       FUSION 550 SPECS:[/B]
    Boost Knob                          (See Gain Knob Above)
    Tweeter Volume                      Horn Bi-Amp (Bi-Amp Ratio Adjustment)
    Woofer/MASTER Volume                MASTER Volume
    Tweeter Hi-Cut Button (Above 10KHz)
    Woofer X-Over Button (Above 5KHz)
    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.

    [B]2001RB SPECS:                       FUSION 550 SPECS:[/B]
    Gain Knob                           Same Controls as Channel 1
    Edge (Overlapping Treble)
    Bottom (Overlapping Bass)
    Input Level Knob
    Shared EQ Settings
    Shared Voicing Settings
    Shared Boost / Output Settings
    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.

    [B]2001RB SPECS:                       FUSION 550 SPECS:[/B]
    Four 4-Pin Speakon Outputs          Two 4-Pin Speakon Outputs
    Four ¼” Outputs                     Two ¼” Outputs
    Right Level Knob (Dual Mono only)
    DI Output                           DI Output
    Pre/Post EQ Button                  Pre/Post EQ Button
    DI Level Knob                       DI Level Knob
    Dual Mono/Bridged Switch
    MIDI Footswitch Jack                TRS ¼” Footswitch Jack
    Tuner Out                           Tuner Out
    Effects Loop Send/Return Jacks      Effects Loop Send/Return Jacks
    Remote Trigger In/Out Jacks
    Chain In/Out Jacks
    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.


    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.


    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.


    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. :D


    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.


    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…
    son_of_mogh and Losbass like this.
  2. skiscem

    skiscem Supporting Member

    thanks for the review, very deep and helpful, if you are going to say good bye to the 2001 rb, she is very welcome in my house ;)
  3. Buzz


    Feb 3, 2004
    Metro Detroit
    My favorite line.

    Wonderful comparision. Detailed and thorough.
  4. NorCal Dog

    NorCal Dog

    Nov 28, 2005
    ATTA-BOY BOO :hyper:

    great format for your review, a very good read
  5. JGR

    JGR The "G" is for Gustav Supporting Member Commercial User

    Jun 29, 2006
    President, CEO, CFO, CIO, Chief Engineer, Technician, Janitor - Reiner Amplification
    Thanks Boo! - please comment on the power - I'm a little hesitant to give up that much going from the 2001 to the Fusion. Also, any idea why they used the old 500 watt section from the 1001 instead of the updated 750 watt section from the current model?

  6. JanusZarate

    JanusZarate Low End Avenger Gold Supporting Member

    Feb 21, 2006
    Petaluma, CA, USA
    No idea, really. Perhaps weight was a concern?

    However, I don't think they used the old 500 power section design - AFAIK, they redesigned the new 700W poweramp and reduced its overall power output. So it's Mark II style, but with an amount of power more like the 700RB-II.

    I wouldn't be too worried about the power difference - I just added a section above to address your concern. ;)
  7. JGR

    JGR The "G" is for Gustav Supporting Member Commercial User

    Jun 29, 2006
    President, CEO, CFO, CIO, Chief Engineer, Technician, Janitor - Reiner Amplification
    Thanks Boo!
  8. OldogNewTrick


    Dec 28, 2004
    Germany, EU
    excellent review - thank you for the effort ! :bassist:
  9. silky smoove

    silky smoove Supporting Member

    May 19, 2004
    Seattle, WA
    This is upsetting.... Between the Fusion 550 and the MB2-500 my 2001RB has been developing self-esteem issues lately :p

    Glad to hear you liked the Fusion so much. I need to track one down and give it a spin.
  10. rag


    Mar 24, 2003
    Robert A. Gallien, President Gallien-Krueger
    Very good and accurate review. My only comment is that I chose the 500W power amp (from the 700RB-II) because with the tube front end it would handle all but the most demanding concert stages. The weight, size and cost savings are the benifits.
    son_of_mogh likes this.
  11. Blessing Sword

    Blessing Sword

    Dec 5, 2007
    That was an amazing review, the format was perfect and the info you gave was very detailed. GK has been giving me so much GAS lately that I can't stand it lol. I hope more people take a cue from this review on how to do an A/B test. Great work man :bassist:. Oh, and I'll more than gladly take a donation of a 2001RB to help me get a real rig going :ninja:
  12. Mike Shevlin

    Mike Shevlin

    Feb 16, 2005
    Las Vegas
    Great review! I had the good fortune of plugging into the Fusion 550 at winter NAMM & your review is spot on perfect. A lot of people who may not have considered a GK are now going to want this head. GK attack with smooth tube tone & VERY loud.
    madjazzbass likes this.
  13. willsellout

    willsellout Supporting Member

    Aug 13, 2002
    Fort Wayne, IN
    Sweetwater Sales Engineer
    If there is a "best review" award, I'd give it to you. I'm glad you dig it. I can't ever see getting rid of mine, it's just too perfect for what I need.
    madjazzbass likes this.
  14. Vinny D

    Vinny D

    Jan 9, 2007
    Warwick, RI
    Probably the best review I have ever read on any forum, nicely done!
  15. Frankie Fender

    Frankie Fender Supporting Member

    Welcome to TalkBass RAG! Thanks for your reasoning. You'll find that many of us here are big fans of GK.
  16. rag


    Mar 24, 2003
    Robert A. Gallien, President Gallien-Krueger
    Thanks Frankie, I am a regular reader but have not posted.
  17. I can see my trading in my 1001 for a fusion when they hit australia. My poor wallet
  18. paganjack


    Dec 25, 2007
    Los Angeles, CA
    awesome review, boo!

    it's nice to know that the wait for this amp didn't turn into a 'Daikatana' sort of thing, and come out after so many delays and then be all lame. Sounds like it's a success!

    Can you post some sound clips maybe?
  19. Is it possible for some sound clips?

    I'm getting some serious GAS here!
  20. JanusZarate

    JanusZarate Low End Avenger Gold Supporting Member

    Feb 21, 2006
    Petaluma, CA, USA
    EDIT: If word spreads here about that, you might find your PM Inbox will be quickly filled. :D

    I can't at the moment. No recording gear other than a mic (Sennheiser MD421), an XLR cable, and nothing to plug either into. :meh:

    I'm working to rectify that, but for now, I have no clips to provide...

    It's also why I haven't been able to deliver soundclips of my pedals in the Effects forum. I don't have unlimited funds. :p

    My band is supposed to be recording our full demo sometime soon, once we get our new lead up to speed... perhaps that would be the best way to showcase the amp in action.

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