Alembic SF-2 and F-2B?

Discussion in 'Amps and Cabs [BG]' started by Brendan, Apr 10, 2003.

  1. Brendan


    Jun 18, 2000
    Austin, TX
    Hi kids, I'm out for a new rack toy, I think... (the GK700RB was voted off by a panel of judge).

    I know the F-2B is a dual channel Preamp that's based on the Fender Bassman sound, ergo big and tubey, but what interests me is that I hear you can loop Channel A into Channel B, which is a high enough output to overdrive B, and get a nice OD sound. Anyone have any experience with this?

    But I'v heard not much about what the SF-2 really is, aside from a filter that "acts as a mega-EQ, essentially." Just what the HECK is this thing, and how does it function? Alembic's website isn't very helpful. This was suggested to me by Peter McFerrin, and I almost sort of trust his reccomendation. Ish.

    Beings that I already have a preamp, I could go either way without losing out. Just what the heck is up with the Superfiler, and the F-2B? And will they drive my Carvin DCM100 fully?

  2. geshel


    Oct 2, 2001
    F2B: I've tried running one channel through the other. It might sound good for guitar, but for bass it seemed like fart city to me. With any volume on the first channel, the second channel is overdriven, and not in a good way IMO (it's not harsh or fuzzy, but it's pretty farty like I said). I've had much better luck putting a little gain between the bass and a single channel of the unit, to get a softer overdrive.

    SF2: Well. . .it's not easy to describe in terms that you're used to, I think. Here are the things you can do with one channel, that I can figure:

    - boost lows, or highs, by up to 10dB
    - roll off lows or highs at 12dB/oct
    - boost a band of frequencies up to 10dB

    For any of these things, the corner / center frequency is continuously adjustable from 40Hz to 6.3kHz. Also, the "reciprocal damping ratio" (Q) knob can add a "peak" to the corner of the filter, so for instance you can have a low pass at 2kHz, but with a high Q it'll go up to about a 7dB peak at 2kHz before starting to roll off above that. Low Q, it just is flat up to 2kHz then rolls off from there.

    On my "clean" channel, I have direct at 100%, and use the filter gain to mix in everything over (high pass) about 300Hz - sort of a 0-10dB special midrange boost. I have the Q knob at the lowest.

    On my "dirty" channel, I just use it as low pass (direct 0%) at 6.3kHz to cut out some fuzz and high squeakyness from the SansAmp. Q in the middle for a bit of a low-treble peak.

    Here's a sample of the whole thing (with the SansAmp on the "dirty" channel), not that you can tell much from this without hearing how the bass sounds dry etc, but just cuz I have it online already :)
  3. I recently switched over to using an SF-2 and F-1X set-up. the preamp is basically a single channel version of the F-2B. Surprisingly, I haven't felt the need to blend in the filter at all (yet.) My preamp is so deep and rich that it sounds pretty good as is; big and tubey for sure. Daisy-chaining the two channels on the F-2B popular is with guitar players like David Gilmour. I don't think I'd bother for bass tho'... I don't have any problem driving my PLX3002 to full power with my Alembic, you could always use the SF-2 to boost your signal if need be.
    Do you need another preamp? the Alembic is a real keeper with it's buttery tube tone. I am going to get myself an SVP-Pro as a counter point to the F-1X's wide clear tone. You maybe wouldn't want to end up with two preamps that were the same or similar in tone? Something to consider..
    the SF-2 is an amazing tool but most folks don't really need this degree of's a deep box. You can run it in series or parallel, mono or stereo. I am going to set-up mine to drive a sub with just the LP signal; kind of like a Bag End ELF system.

  4. geshel


    Oct 2, 2001
    This would be the same thing effectively as using the crossover in the F-1X. The ELF is something different altogether.
  5. Fuzzbass

    Fuzzbass P5 with overdrive Supporting Member

    Been using my F2B since ~1985. I've tried stacking the channels, and liked the result. Using caution with the levels, it's possible to get mild overdrive as opposed to farty distortion. The reason I don't do so is because I don't often use overdrive of any sort, and when I do it's much easier to switch my SansAmp BDDI in and out rather than do on-the-fly precision tweaking of F2B levels.

    The SF2 does intrigue me because I would like more tweakability than the F2B provides. Sometimes I like to dial in a bit of mid honk, which isn't practical with the cut-only mid control on the F2B. My ideal solution would be to find a warm/phat tube pre which has active mid, rather than adding another pre as I'm doing now (tc electronics PQ). That said, F2B + SF2 should provide all the tweakability one could hope for IMO.
  6. geshel


    Oct 2, 2001
    That's one thing to keep in mind: with a two-channel pre and a two-channel "EQ", the number of setups is pretty large, and it can induce sever tweak-itis! Sometimes simple is good. ;)
  7. geshel


    Oct 2, 2001
    Oh yeah - one thing that bugs me about the F2B is no effects loop, and inputs only on the front. So you've always got to have the space somewhere to run a cable around to the front if you use any other stuff in your rack.
  8. Hmm. You are essentially correct. The SF-2 will give me slightly more "flexibilty" than just a regular X-over but not much. My take on the ELF is that it is just a fancy filter interacting with your signal that not only provides an extended low end but also a flat response. The SF-2 is of course, nothing like that because it just boosts everything regardless. Ah well. My system will be a poor man's version.
    One thing i am looking forward to doing once I score a proper sub (good to 30hz, 4 ohms) is driving it with the sub out of my DBX 120XP. Oh yeah. Bin shaker.
  9. Fuzzbass

    Fuzzbass P5 with overdrive Supporting Member

    Re geshel's comments:

    The F2B front-panel inputs work perfectly for my current KISS rack: bass plugs into F2B (the latter in set-it-and-forget-it mode), I then go to compressor, parametric, amp. When I ganged channels the front panel inputs DID become a PITA, having to wrap around from rear output A to front input B. Geshel, sounds like you use the F2B in the middle of your rack's signal path... inconvenient, that... :)
  10. Bootsy uses an Alembic F2-B? Must be good! (You can see it in his rack...)

  11. Mario Lewis

    Mario Lewis

    Jul 6, 2001
    Clinton, MD
  12. Fuzzbass

    Fuzzbass P5 with overdrive Supporting Member

    I think I'm seeing double!

    Excellent photo, MadSub. :)
  13. geshel


    Oct 2, 2001
    Interesting. The F2B seems most like an "end of the chain" thing to me. It can put out a good amount of voltage, so I picture it driving a power amp directly. (I guess that means it's not at the actual end of the chain).
  14. tripwamsley


    Jan 31, 2002
    Sulphur La,
    The Superfilter is a great device. I have used one since 1999 and with tasteful settings you can get everything from the most obscene low end to wonderful clear highs. It it quite handy for troublesome rooms, which, we all have to suffer through. I find it almost indispensable. I say go for it!:D
  15. jokerjkny


    Jan 19, 2002
    NY / NJ / PA

    and thusly, my interest has been piqued!

    anyone else wanna chime in?
  16. Eric Cioe

    Eric Cioe

    Jun 4, 2001
    Missoula, MT
    You like to resurrect old threads, don't you? ;)

    I just wanted to add that stacking the channels on a F-2B, if it sounds like stacking the channels on an old Fender Bassman, is awesome. You have to be careful with the gains on each channel - I keep mine at 6 with low gain tubes (GE 5751s). It is very useful, powerful, and fun.
  17. I've considered the SF-2 a couple of times but I figured I'd fiddle with it so much that I would never get around to playing any music.:meh: