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Amp for Low F#

Discussion in 'Amps and Cabs [BG]' started by Kraig99, Jun 11, 2002.

  1. How much power will I need to get a good sound out of a low F# string? What are the possible disadvantages of using a low F# string on a smaller combo? Will it just sound bad at any volume, or will it just be difficult to hear it at a high volume? Thanks!
  2. BUMP!! I know some people here use a Low F#!
  3. Nick man

    Nick man

    Apr 7, 2002
    Tampa Bay
    Im sure one of JT's 7 or 8 string Conklins have a low F#; try asking him.

    I think Ive heard that most people use PA sub woofers, but Im sure a good 2-15" cab should work nice, as long as its tuned to a low freq.

  4. VicDamone


    Jun 25, 2000
    I can't give you a very substantial technical explanation but...your preamp/amplifier section of your combo more than likely has the capability of amplifing the low f#. It's the speaker system that may have a problem reproducing such a low frequency with a volume equal to the notes on the E string on up.

    Even if you had 2000 watts on tap, the speaker and/or the enclosure will roll off at a certain frequency and choke the lower fundamentals of the lower notes. There are frequencies within that low f# (overtones) that your combo may reproduce very well.
  5. IMO, you won't find solid low F# (23 Hz) in a commercial mainstream cabinet. You will have to roll your own. There might be some specialized (read: expensive) cabs that will do the trick (Meyer or ??).

    Download my spreadsheet from my signature and sort the DRIVERS tab first by column R, ascending and second by column F, descending. This will show you the various drivers that can reach an F3 of 23 Hz, sorted by the loudest first.

    You will find that drivers capable of 23 Hz are not very loud, or they require tremendously large cabinets. Look at the JL Audio and Rockford RFR-xxxx drivers.

    I have no need of 23 Hz, so I reduced the cab size of my Rockford RFR-2215 drivers for optimum performance to 31 Hz (low B). Right now, I run two 1x15 and two JBL E110, bi-amped. This gives me very deep, clear bass all the way to low B.

    If you are intent on going down to low F#, you will need a bare minimum of two 15" drivers, and preferably four. Count on needing a few thousand watts to drive them. I use a QSC PLX 3002.
  6. Suburban


    Jan 15, 2001
    lower mid Sweden
    Or have a look at Joris' homepage.

    Not loud, but... And perhaps you'll need another box to go down the last 5Hz, but that's an "easy" trick.

    JAUQO III-X Banned

    Jan 4, 2002
    Endorsing artist:see profile.
    I use a Low F# and I use a Low C#.to clearly get your Low F# there are a few factors that need to be addressed 1.is your Low F# string tight enough,if its loose and slopy like a bad Low B that will have to be dealt with first.for the proper tightness will be your guide to better clarity for your Amp and Speaker(s) and the best string for that would be a taper core style.2.you will need proper headroom from your amp the more wattage the better for volume and clarity.3.cabs I prefer at least 4 10's but you can pretty much use any cab setup you like even 2 12's if you choose.there's more to it but once you get these basics down the rest will come a little bit easier.
  8. gorgasm


    Mar 10, 2010
    Ok... so I've done all that, now what? im using an Ampeg SVT-3 pro and a classic Ampeg 4x10 cab. How do I make this F# purr?
  9. read the other replies in the thread
  10. Hi.

    I asked the same question a while ago, when stringing my 6er for F#BEADG idea came up.

    Being a DIY "tech" and somewhat well versed with the physics behind the amplification of low end and the demands the low frequencies place on that, I worried a lot.

    My understanding was that on order to get any definition below B, You have to have at least a few hundred watts, and a rig that goes down to about 25 Hz f3.

    One of the people on the know (the "knuckle-works guy"), said that a solid 40Hz IIRC, was enough. That really wasn't the answer I thought I'd get, and quite frankly, didn't really believe it even though I do recognize his experties on the field.

    Little did I know.

    When I strung the bass with a Warwick DL set + BL D&G, an old SWR WM10 was all that I got at home. To my total surprise, the low notes were distinguishable, right up to the point when the replacement Hartke XL speaker on that 80W combo started to complain, which was surprisingly loud.
    Not anything ground shattering, or giggable, and the unbalance of the different strings required quite a bit of tweaking, but the definition was there.

    I haven't benched the WM10, but an educated guess would be a f3 somewhere around 50 hz.

    On to the big rig then.

    A production MI tube amp is never going to reproduce even low B fundamental with any balls. Anyone who's ever run a signal generator through a tube rig knows that.
    On my cheapo Fame BVH300, a "perfect" sine of 45Hz/200W looks like a saw-tooth that's hit a nail when the frequency gets nearer to the 30 Hz mark. Then again, 200W/40Hz through a TL606, won't shake any walls either.

    Even though the Fame+Laney 410+HK15 will have the f3 of about 45Hz, I have gigged with it in smaller places. The F# (or the B for that matter) won't make Your pants flap, but the definition should be there, and nothing beats the "coolness factor of a .175 string :).

    So go ahead and tweak, unless Your expectations of the SPL in the sub bass aren't unreasonable, Your current setup should be able to handle it.

  11. So a tube amp can't reproduce fundamental low frequencies without distortion?
  12. Hi.

    No, it can't.

    The size (FeA) of the transformer is directly proportional to its ability to reproduce low frequencies. Since the price of the transformer is closely linked with its size, the manufacturers seek out a passable middle road.

    A good rule of thumb I often use is: an octave down=twice the cross sectional area of the core.

    It's no that important though, the fundamental is usually quite low in a bass instrument anyway.

  13. indeed, I'm sure that same distortion is part of the reason why some folks like the tube amp sound so much ;-)

    Interesting bit of information indeed though, thank you
  14. top028


    Dec 14, 1999
    Lancaster, PA
    Not disagreeing with T-bird, just pondering that Hammond transformers are rated at 20hz-20 Khz (price reflected!). They may be able to handle the sub-lows at lower power, if the amp doesn't have low freq. roll-offs built in to prevent oscillation (ie, my Traynor w/hammonds.) Also using the lowest cabinet impedance that a transformer can handle shifts freq. emphasis, so I have read. I notice a big difference in using my Fender bassman 100 with an 8 ohm cab by itself. Sometimes for fun, I hang three 15's and two 10's off it (2 ohms), It gets my pant legs flapping! Then again it could be the giant surface area of all those cones.

    I am planning to build this cabinet in the near future.
    Looks good on paper anyway. I like the concept of efficiency with horns...other guys have built this with good reviews.

    check out these Great articles from ESP: (amazing resource for DIY)

    secrets behind ELF systems from bag end

    really awesome article about Bi-amping and the power it takes to drive different frequencies. 350hz is the even point watt-for-watt!!
  15. Bassmec


    May 9, 2008
    Ipswich UK
    Proprietor Springvale Studios
    ?! You need to test a good Bass MI tube amp instead then.
    A Simms Watts AP 200 with the stock ultra linear partridge transformer is very clean at 200watts rms at 20 hz.
    You must be testing cheap guitar amps mate.:D
  16. Hi.

    ^OK, there's a select few that can :).

    A vintage Partridge OT aren't a typical run-of-the-mill transformer though.

    Entirely different matter is that mere 200W/20Hz with any amp, to any dynamic speaker, will sound rather anemic. (Unless You're sitting inside the cab that is)

  17. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    If that was the case tube amps wouldn't rule the roost in audiophile circles. Whether or not a typical musical instrument tube amp can do so is a different matter.
  18. Ben Coffin

    Ben Coffin

    Dec 8, 2009
    Auburn, AL
    Take a look at Bag End Amplifiers. I played their cabs at NAMM this year and was happily surprised to find incredible response and clarity with low strung basses. They make 18" cabs and I believe 21". Of course this only helps if you are considering new cabs.
  19. you'd think that a bass amp would be made to reproduce the full bass spectrum as a standard design objective :smug:
  20. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Consider the SVT. With the original speaker bandwidth of roughly 40 to 4kHz anything in the amp to realize a wider bandwidth than that is moot, though of course it did. If anything with the limited capability of the original drivers you'd want that head brickwall high-passed at 40Hz to keep from toasting them. That caveat should have been applied to virtually all electric bass amps produced prior to roughly 1980, but of course it wasn't.

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