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What is flat EQ?

Discussion in 'Amps and Cabs [BG]' started by the low one, Oct 10, 2009.

  1. JayfromDeeKay


    Jun 23, 2009
    That's funny; my Trace Elliott Commando 15" amp has 3 tone controls (bass, middle, treble) and 3 knobs next to each tone control (Deep, Mid-shift, Bright). Maybe it's another revision of the same amp.
  2. Munjibunga

    Munjibunga Retired Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    There is no mid sweep knob. It's a button. The only thing I can think is that the EQ controls are boost only, so 12 o'clock is half way up, and the mid shift button is changing the frequency of the boosted mid.

    Try turning the mid all the way down, then see if the button changes the tone. Also try it with all the EQ knobs all the way down to see if they're boost-only. "Flat" may be bass, mid, and treble all the way down.
  3. R Baer

    R Baer Commercial User

    Jun 5, 2008
    President, Baer Amplification
    But keep in mind that some amps already have a "overhyped" Eq curve built in with all the knobs at noon and some don't. Look at it this way. If Amp #1 has a bult in +6dB top end boost (and many do), then a quarter turn of the treble knob on that amp is going to result in a very large variance away from flat, even though you barely moved the knob. But let's say that Amp #2 doesn't have a built in top end boost, then you may find that you have turn the treble knob of that amp up to the 3:00 position just to arrive at the amount of treble boost that is present in amp #1 with the treble knob at noon.

    That's why I always stick by my notion that knob postition is irrelevant. If you can get an amp to sound great for you, don't stress over where the knobs end up. It's quite possible that your amp can have a flatter response curve with the knobs all over the place, than it had with all the controls at noon.
  4. ehque


    Jan 8, 2006
    If it's a passive tone stack...

    Well, some passive EQs on amps (guitar, mainly) were designed to be "flat" at max-mids, minimum bass and treble.

    But really, just switch the switch back and forth until you hear no difference between the two positions.
  5. Bassamatic

    Bassamatic keepin' the beat since the 60's

    All instrument amps have some "flavor" already engineered into them, and so do the cabs, as mentioned above. That's a main reason they don't all sound the same. It is really little problem to make amps and speakers have fairly flat response, but we probably would not like them, if they did!

    So - the truth of the term "flat" when referring to instrument amps is very different from "flat" as used in PA or the studio, meaning no EQ - frequency response as even as possible. Perhaps a more accurate term for instrument amps might be "Centered" or "Zeroed" instead of "Flat", but I think that most people understand the implications when the term is used for an instrument amp.
  6. mongo2


    Feb 17, 2008
    Da Shaw
    I was taught that flat EQ is when the tone of the output is identical to that of the input.

    It can take some knob twiddling to get if it can be got, and then you have to decide if you really want that, just like any other tone.

    I just make it sound good in my situation and I'm done.
  7. I thought the mid shift controls on Trace amps were a preset EQ voicing not an adjustment of how the mid control worked, it's usually called "shape" on most of them. Played on the combo I think your talking about a while back and it acted like that anyway.
  8. greenboy


    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    Hahahahah! That's taking an optimist's point of view. Arguably though, some of that is not engineered in by design choice or mad skilz - it's there because of cheepniz and sometimes even bad skilz. But on the other hand a lot of bass players probably can't EQ very well either so I suppose some sort of hidden default voicing will save them from figuring out how they want to voice their amp and a lot of the buying of gear is really just paying someone to EQ for you ; } ...I do like being able to buy different gain structures and non-linearities though, because that very much translates into feel, and not just sound.

    Again I laugh ; } - how little you seem to know! People torture themselves to get closer to this with drivers and enclosures. Audio forums are rife with projects trying to get closer. Companies strive. And it's always just out of grasp no matter how much money and expertise you throw at it. Even getting 90% of the way toward the seeming horizon is not easy.

    Three for three in my book now, Gio S ; } - Plenty of bassists have heard good DI through good studio monitors and did not find it in the least objectionable. Some just wish they could get that more often. So now you seem pessimistic, as if you didn't believe electric basses could sound good without "cabinet massage" er, cabinet mess-age. That's just crazy. Good basses sound great! Anything from vintage P basses to standups to modern active composites can sound great, exposed and wide open. They usually do, in fact.
  9. If you had a 24 band eq and a parametric eq, you could get close to a "flat" eq, using the right equipment to measure the curve...but, the eq's would look very strange with frequencies boosted or cut based on the room you were in, the volume level you were playing at,the surface your amp was sitting on, the temperature in the room, the amount of people in there, etc...in my experience, it sounds kinda weird next to your amp, and you might not hear yourself well over certain instruments, and may or may not sound good out in the house, based on whether or not other instruments are eq'd...example, everyone carefully eq's totally flat, and when the band plays, they double or triple up on 100hz-250hz just because everyone is playing even responses across the spectrum, and the room itself wants to resonate at a frequency in that narrow range, so a "flat" eq will attenuate some sounds and supress others...kinda like chasing your tail!
  10. the low one

    the low one

    Feb 21, 2002
    Mine is the same. Do you get the same change in mid frequencies when engaging the mid shift button?

    According to the manual..... "The mid shift contril changes the frequency at which the mid control opperates"

    Munjibunga, you made a good point about the controls may be boost only. I'll look into that further thanks.
  11. JimmyM


    Apr 11, 2005
    Apopka, FL
    Endorsing: Yamaha, Ampeg, Line 6, EMG
    Good points that I never thought of. OK, I shall not fear a tone knob on 10 anymore!!! Thanks, R!
  12. bobcruz


    Mar 10, 2004
    If the tone controls on the OP's amp are passive, doesn't that mean that they are "cut only" and that "flat" would mean "no cut anywhere" so all the knobs would have to be maxed? So with his mid knob at 12 o'clock, he's cutting mids at some frequency and he can hear the change when he shifts that frequency.
  13. JimmyM


    Apr 11, 2005
    Apopka, FL
    Endorsing: Yamaha, Ampeg, Line 6, EMG
    Not necessarily. A Fender tone stack is passive, yet the treble and bass are boost only and the mid is cut only. Someone once explained to me how that works, but I didn't retain any of it.
  14. B-string

    B-string Supporting Member

    The trouble with any type of EQ? At every center frequency you create a notch if you boost or cut, further coloring the sound. :ninja:
  15. greenboy


    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    Actually cutting creates a valley and boosting creates a peak. Notching infers a deep high Q cut... Anyway, if it's actually flatness one is after a sufficiently accurate EQ move counters a peak or valley in speaker response and it's no big deal. Nor is it any big deal if it effectively counters a local acoustic dip or bump. This again, is just addressing EQ for FR adjustment - not tonal preferences.

    But you can't EQ for room reverb characteristics or LF wavelength cancellations and reinforcements at various frequencies for every listening position.
  16. plug into the effects return to hear your amp's least effected sound. Of course that does nothing for the cab effect.
  17. R Baer

    R Baer Commercial User

    Jun 5, 2008
    President, Baer Amplification
    Anytime Jimmy. We've been dealing with this concept a lot. Our amp designers come from a background designing high end studio gear while I add the live bassist perspective. Many heated debates have been had over what the "flat" response of the amp should be and things like "acceptable" distortion levels in the tube circuit.
  18. R Baer

    R Baer Commercial User

    Jun 5, 2008
    President, Baer Amplification
    A big part part of the picture lies in what an amp company decides they want their "sonic signature" signature to sound like. If every company out there decided to go for ruler flat response curves and pristine reproduction of your instrument, then you wouldn't have the Ampeg sound, SWR sound, GK sound, etc..., to choose from! I do think more and more bassist today are coming around to the idea of a less is more approach when it comes to amplification.
  19. greenboy


    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    I sure have. I want a lot less hidden default voicing/EQ that just gets in the way or counters my preferences and makes mix-and-match such a time-consumer and wallet eater. There will always be differences in amp design by circuits and components anyway. The stuff I've tended to like the best has the least of this pre-supposing built into it.

    But I do like what MI amps can offer in terms of response non-linearity, and how that can be applied to output curves and musical distortion.
  20. R Baer

    R Baer Commercial User

    Jun 5, 2008
    President, Baer Amplification
    A lot of it too is getting players ears used the sound of their instruments without all the hype. Our system has a very flat response compared to most amps and a lot of players that have tried out our prototype tend to automatically boost a little treble and bass and cut some mids as soon as they start playing, to get back to what their ears are used to hearing. I usually recommend that they try it with everything flat for at least 3 or 4 tunes before tweaking the EQ. In most cases their ears start to adjust to hearing more of their instrument and their technique and less of their amp pretty quickly.
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    Primary TB Assistant

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