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Potentially Harmful Tuning

Discussion in 'Amps and Cabs [BG]' started by kleinenenten, Aug 22, 2012.


  1. So my band was talking about possibly tuning to A for a few songs, but I was wondering about the possible issues it may cause for my gear. I have recently heard that if you push your cabs too low, they'll blow, especially if they're ported. I'm currently running a GK 410 Neo which is front ported and rated for about 30Hz, which as far as my research tells me is right about a low B's frequency. A low A is about 27Hz from what I've read, clearly below my amp's design specs. This morning I briefly tried a low A at low volume, and the amp just didn't sound right. I don't know if it was me just not being used to the A, or if the amp was legitimately having problems.

    So I guess what it comes down to is this: Will tuning to low A hurt my cab in any way? Just got this rig and I love it, don't want to kill it already.

    Thanks in advance for the input!
     
  2. My Trace amp has a 30hz slider with a red cover to emphasise the instructions in the manual. Cutting the low bass EQ gets you much more usable volume before the speaker farts out.

    Your cab rating of 30Hz is probably a -10dB response, meaning you would have to give it 10x the power to make a low B sound as loud on its fundamental as say your open G. It is probably making just enough 60Hz to satisfy the bottom B and draws the line at 54hz.

    Most cabs struggle with the fundamentals all the way to F. The speaker just can't move enough air. The F-deck HPF is the goto solution for this problem.
     
  3. Exploiter8

    Exploiter8 Demons run when a good man goes to war

    Jan 18, 2010
    Midwest
    Commercial FREE!
    Won't that totally mess with your bass's setup, too?

    X8
     
  4. will33

    will33

    May 22, 2006
    austin,tx
    Potentially harmful to your bass. Girls don't much like it either after a bit.
     
  5. WingKL

    WingKL

    May 12, 2007
    You have a GK 700RB II don't you? Set the string selector to 4 string and you won't have to worry anymore about going below your cab tuning as it mimics the high pass filter of the older RB series amps. It'll make your bass sound clearer too.
     
  6. Mr. Foxen

    Mr. Foxen Commercial User

    Jul 24, 2009
    Bristol, UK
    Amp tinkerer at Ampstack
    Fundamentals of notes barely come out of your bass, so can pretty much ignore the 27hz thing. Problem it if you don't sort your strings and bass for that tuning, the tone from your bass will be pretty duff, and there is a tendency to turn up to try and improve matters, and there is problems there. The richer sound of heavy strings will improve audibility, and cut some lows on EQ and you are good to go.
     
  7. I guess there are things I'm missing here. What is a "fundamental"? Also, doesn't the 4 string setting on my head limit the range of bass somewhat? I know I don't want to blow speakers, but if I'm going to tune that low, I'd also like to hear it. Maybe I'm misunderstanding something. Thanks for the help so far!
     
  8. 1958Bassman

    1958Bassman

    Oct 20, 2007
    The low B, at about 32 Hz, is hard enough for the bass to produce at the same amplitude as the other strings but the speakers need to produce a lot of energy in that range. In a small space, it's not so hard but in a large room, even response it harder to achieve. As you mentioned, frequencies below the port tuning causes problems and if you don't know exactly how a port works, here's a simple explanation- blow across the top of a bottle and listen to the note, then add water and listen to the change in pitch. You have just re-tuned the bottle by shortening the length of the cylinder. A port operates best at one frequency- its tuning frequency. The volume of any notes it may produce is greatly reduced above and below that frequency and all a port is designed to do is help to extend the low frequency response. It's tuned below the sealed box's effective range and is supposed to be tuned so it blends well, i.e., the speaker/box's -3dB point and the port's -3dB point just about coincide and don't cause a noticeable bump unless it's A) needed, B) wanted or C) won't cause a problem. Below the port tuning frequency, it acts like an uncontrolled leak in a sealed box. Because a port works well at only frequency, the rest provide some resistance to the cone's movement but below, it can shake itself apart through over-excursion. It's pretty ugly when this happens.

    If you want to use this tuning, find drivers that work well at low frequencies in a sealed box and make the box as rigid as possible. No leaks can be tolerated, at all. A minor leak in a sealed cabinet is a really bad thing for the tuning- if you have a small leak, you might as well just drill holes and make it a large leak. some amps, like the Peavey IPR series, have sub-harmonic enhancement but I wouldn't recommend using that with a ported box that is tuned higher.

    BTW- the amp should be able to handle 27Hx- it's stated frequency response and distortion specs should go down to at least 20Hz but if you play double-stops, the difference between the notes can produce notes that are below 20Hz. If you use harmonics to tune at the 5th fret, the slow pulsation just above and below correct tuning is called the "beat frequency" and it's the main reason amps sometimes have a subsonic filter.
     
  9. 1958Bassman

    1958Bassman

    Oct 20, 2007
    The fundamental is the lowest frequency at which something will resonate freely, without overtones (harmonics). If you pluck the open strings half way between the bridge saddle and the nut be the fret, you notice that it sounds kind of mellow, without as much "tone". Then, if you pluck it and use the harmonic at the 4th, 5th, 7th, etc frets, you can hear it clearly. This is because the string is vibrating at some multiple of the fundamental frequency, based on the distance between the two points.

    Here's a link- don't worry about the math unless you want to.
    http://en.wikipedia.org/wiki/Fundamental_frequency

    If you read comments about acoustics that refer to "standing waves", this is the same thing.
     
  10. Mr. Foxen

    Mr. Foxen Commercial User

    Jul 24, 2009
    Bristol, UK
    Amp tinkerer at Ampstack
    The hertz numbers being quoted are the fundamentals, for them to come out of a bass as a significant portion of its output, the pickup would have to be at the 12th fret. They are basically irrelevant to tone, you can high pass at about 50hz and not really notice even a lack of bottom end. A sealed box will roll off lows a lot, I had an 8x10 and the high pass was at about 100hz before noticed much, even then the tone was still complete, lows don't do much for pitch.
     
  11. PaulKos

    PaulKos

    Sep 3, 2012
    I am having a big problem or question but I don't find the right thread!!! I am tuning my double bass pizzicato and piano playing and it tunes perfect but when I am bowing it the notes goes a lot(twelfths) of sharp. When I am tune it playing acro it tunes perfect but when I am playing it with fingers pizzicato the note goes down(flat)... Can anyone help me???
     
  12. PaulKos

    PaulKos

    Sep 3, 2012
    Sorry for my bad English,can anyone help me???
     
  13. Mr. Foxen

    Mr. Foxen Commercial User

    Jul 24, 2009
    Bristol, UK
    Amp tinkerer at Ampstack
    Without frets, don't you just need to put your fingers somewhere where it isn't out of tune? Also, not really an amps issue.
     
  14. rpsands

    rpsands

    Jul 6, 2007
    Phoenix, AZ
    They can tune to A and you can just play in the same octave with the bass knob up, neck pickup dimed, and play toward the neck. It'll still sound heavy and beefy. This is safer than using a conventional cab tuned to low A.
     
  15. PaulKos

    PaulKos

    Sep 3, 2012
    Sorry sir I usually tune open strings... and yes its not an amp issue
     
  16. DerTeufel

    DerTeufel Supporting Member

    Nov 11, 2011
    Wildomar, CA
    Sounds like a technique issue if your intonation is off on a fretless.

    You should have posted this in the double-bass technique section, not bass guitar amp section.
     
  17. Primakurtz

    Primakurtz Registered Nihilist Supporting Member

    Nov 23, 2011
    Denver, Colorado
    I tune my 5-string'ers to low A. Other than minor increases in local seismic activity and bowel momentum, it works just fine. The above advice about amp settings is good.
     
  18. PaulKos

    PaulKos

    Sep 3, 2012
    the funny thing is that you don't even understand what I am saying....
     
  19. PaulKos

    PaulKos

    Sep 3, 2012
    Tunning my bass...(back then) piccicato and tuning it with the bow, notes had a big deflection... of course I am talking for open strings and of course I was asking if this has to do something with my crappy company made edb and its amp that I had back then... Simple question for those who know and understand. And for the up coming comments yes... I don't even have a bass right now. That kind of art its still a comfort from the money perspective... not just for me for millions around the earth...
     
  20. It will be fine... people tune much lower than that over at sevenstring.org and they're doing it at full volume. You'll get a lot of responses about it over there if you want to get more input from people using low tunings.
     

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