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Speaker cone bouncing question...please help

Discussion in 'Amps and Cabs [BG]' started by Larry Kaye, Feb 9, 2004.

  1. Larry Kaye

    Larry Kaye Retailer: Schroeder Cabinets

    Mar 23, 2000
    Cleveland, OH
    Last night I played in a blues jam at a local bar. I brought my GK 400 RB III head knowing just how much I hate the tone of this old Traynor head that the house bassist brings to the gig which with his older P bass fretless really sounds pretty decent for some reason....just not with me playing through it!

    He has one of the heavy duty Ampeg 1 15 cabs about the size of a small refrigerator. Both I and the next bass player used my GK. As you guys may or may not know, the bass tone knob on the GK is like an 80HZ boost. I was using my new G&L Tribute bass which, again, you guys might not know that the active bass boost is more of a low punch than a phattness adding tone..I believe it's at 60 HZ, maybe higher unlike the Sadowsky or Aguilar bass boost which I think is at 40 hz.

    The second bassist was using a 63 P bass. Both of us were making that speaker cone bounce a couple of inches. Neither of us could get a really clean tone out of the cabinet, however, it was still much cleaner than what the house bassist's tone has been. I got a little better results putting a DoD 31 band EQ in between my bass and the head. That seemed to help slightly.

    My question is when I use my sunn 1200 S with my bass and Epifani 212 cab, the speakers bearly move, yet it seems like it's triple the volume, punchier, cleaner with just as much bottom end. Yeah, the head has significantly higher wattage than either the GK or the Traynor.

    Also, when I owned an Aguilar 359, 200 watt all tube amp, I had the same issue. The speaker cones on my cabinets went bizerk, I think I was using SWR Goliath Jr cabs at the time...that's 200 tube watts into 2 2 10's, 700 watt total capacity cabinets. I farted them out regularly. My sunn head, as long as I don't overdrive the tube preamp, got those cabinets at least 1.5 times louder than the Aguilar without anywhere near the speaker cone excersion of the tube head.

    What causes higher cone excersion at lower volume levels with lower wattage amps? It's not as though the GK at 280 watts and the Aguilar 359 are power shy and aren't loud enough.

    Can anyone explain why?

  2. Mark Reccord

    Mark Reccord Supporting Member

    If it's a vented cab, boosting frequencies below the port tuning frequency will cause excessive cone movement even at very low power levels. I don't know what the Ampeg's tuned at but the Goliath II is tuned to 55 Hz, which is pretty high for a bass cab...
  3. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    The problem isn't really the speakers, its the amp......in a way.

    Its sub-audible stuff getting through that adds nothing to the sound, but does soak up amp power. It also uses up speaker excursion big time. Comes from slower string movements during picking, slapping etc, even just moving around while you play.

    What fixes it is a low cut filter. Not necessarily something that sucks out low notes you want, but one that starts taking out response say at 30 and below, and cuts off fast. Should be on every high power bass amp, but usually isn't, not even ours. The Sunn might just have had crummy low end response to start with, mine did.

    The other problem is the low EQ, if it is shelving, it just keeps going until the amp's low end limit. Speakers can't do anything with it, so it doesn't help.

    If you get rid of the garbage, your sound will clean up.

    Actually, you may not lose anything if you either don't boost the lows that far, or if you take out other ranges instead of boosting lows. If you have a graphic and pull down the lowest slider that can help too (if its at 30 or so).

    The old record turntables used to make the speakers flap if the floor bounced as someone walked on it, etc. When I was in the hifi biz we used to fight with "audiophiles" who wanted extended low end response. They had the same problem. Unbelievable the difference it made if the garbage was filtered.

    Oh, yeah, the problem isn't as visible with a sealed cab, but the amp is still wasting the power on inaudible stuff.
  4. Larry Kaye

    Larry Kaye Retailer: Schroeder Cabinets

    Mar 23, 2000
    Cleveland, OH
    I looked at my eq on the Sunn and the Dod and do set the very low end eq sliders (everything under 40 hz) at minus the limit it can be cut. Also, I have the compression set very high on both bass (set at about 7) and highs (set about 8). I use the compression balance to help enhance or negate bottom based on the venue. I'll start it at 10 and move it down to a minumum of 8. That tends to cut the low end overtones.

    Perhaps the compression on the Sunn helps to cut down much of the excess "noise" and other undesired frequencies going to the speakers that cause excess excursion. I would think that a head as high end as the Aguilar would have something in there. I do know that the Aguilar's bass control works the 40HZ area which is below the lowest useable frequency of many of today's top cabinets including a 210 XLT Eden and others.

    Also, I don't boost the low end on either my amp eq or the DOD 31 band. I will slightly boost the bottom on the bass itself if the room absorbs it. I slightly boost around 125. I don't know if the bass tone control on the Sunn is a shelving type or a single frequency. I have it slightly cut actually.

    Again, the SWR speakers did not bounce very much at all with the Sunn head in them. As long as I don't post boost the snot out of the bottom end of the eq or turn up the preamp past the slight clipping stage, I haven't been able to get either my Epifani 212 4 ohmer, or my Low Down Sound 2x8's which are both 4 ohm 350 watt cabinets, to break up playing at my band's full volume. I guarantee you I'm not a quiet bassist and demand that I be heard and felt, but feel that getting a tone that is penetrating without sounding midrange honkey or overpowering lowend grunty is the key to not being "judged" as playing too loud. What's interesting is that even the SWR's at a 55hz tuning according to a previously replier were putting out at least 1.5 times the volume of the Ampeg 1 15 with much more desirable tone to boot.

    Frankly, I think it's a matter of taste too.....I'm not much of sounding like Jack Bruce on Crossroads. I'll take his style, playing, and singing ability any day....I just don't like that grunty heavily grinding/distorting sound. I love it clean and punchy, with enough bottom to make you get up and dance, not to shake a 24 ounce porterhouse on a one pound plate off of your table onto the floor. You can save that for DJ's and crummy live concert mixes.

    This bassist has used my GK, his Traynor, and his Ampeg B5. They all sounded crappy. The GK was the cleanest and if that was my gig, I would have been embarrased to provide equipment sounding like that for others to play, even if they couldn't play that well....at least sound good.

    I've heard many an Ampeg cabinet sound great. As a matter of fact I recently bought the portabass 112 when I got my GK head. With an Ernie Ball Bongo Bass 5 string with 2 dual coil pickups, it sounded unbelievable for it's size. I bring it home and it doesn't sound that good with my G&L, F bass, or Rob Allen. On the other hand, they all sound unbelievable with the Sunn head including in the Ampeg cab.

    I think it's the head first. I'm gonna bring the sunn to the next jam session and see if it's me, the head, or the 1 15 cab that just don't work well together.

  5. If you ask me, the amp must have been clipping severely to the point where it completely lost stability. Adding low boost contributes a lot to the problem. If you had turned down the low bass frequencies completely, you would have been able to play without the cones jumping around. Also, maybe the cab was 4 ohms and the amp could only handle 8 ohms. This will surely lead to instability at even moderate clipping.

    My Eur 0,02
  6. BillyB_from_LZ


    Sep 7, 2000
    Mark Reccord...a G II tuned to 55 Hz? When I measured mine, I came up with a tuning in the low 30s. Same with my former Acme B2.
  7. Petebass


    Dec 22, 2002
    QLD Australia
    Speakers are supposed to move and every speaker has different excursion characteristics. The sub in my car looks like it's about to jump out of the basket, but it has a much higher rated X-max than any of my bass cabs. In other words, it's designed to move like that, so maybe his speaker is the same?

    As mentioned earlier, speaker excursion is affected by cabinet design and tuning frequencies. But I don't think that's the problem here. I too think there's something sub-sonic comming out of the amp, probably in a frequency range which is inaudible to human ears.

    All the cabs I have built have a crude sub-sonic filter. All I do is put a capacitor of appropriate value in series with the positive terminal of the speaker. That's only a 6dB per octave filter and I didn't think it would work, especially since most cabs roll off quicker than that. But I tried it anyway, and was surprised. The speakers visibly move less and I can drive them that little bit harder before hitting distortion. The trick is to get it so the cap doesn't rob any audible bottom end and that requires a bit of trial and error, but it's worth it. I thought about 2nd and 3rd order filters but discarded the idea when I realised how big the inductors would have to be.
  8. Trevorus


    Oct 18, 2002
    Urbana, IL
    what might be even better is using a line level attenuator in your signal chain. That way the sub sonic stuff doesn't even go through the amp. Pete's idea is good, and it does work, but the amp still does produce those subsonic signals. Though the speaker doesn't see it, the capacitor is the one who handles all the wasted wattage. That will protect your speakers, but for efficiency's sake, stopping it before it gets to the amp would make better use of the wattage. Just my $.02
  9. Trevorus


    Oct 18, 2002
    Urbana, IL
    20Hz Line Crossover


    30Hz Crossover

    Get one o' those, and some 1/4" converters, and drop it in your signal chain. Just before your amp would work best. It'll keep ANY amp from having excessive excursion from subsonic noise. Makes your amp more efficient as well.
  10. Petebass


    Dec 22, 2002
    QLD Australia
    Hey I like that idea.

    What I want it to operate at 50Hz instead, or 40 Hz? It says you can combine them to get different crossover points but I can't picture how? Anyone?
  11. Trevorus


    Oct 18, 2002
    Urbana, IL
    I think they mean a high pass and low pass to give you a midrange. It wouldn't work any other way. I'm sure you could find a 50Hz. I'll look around Pete. I think I might do that myself. My little eden 210 has a problem when I crank it. I played a bigger club one time and used it for a monitor. We used a line out for the main, but I had to kick up the level just to hear myself.
  12. Petebass


    Dec 22, 2002
    QLD Australia
    That link didn't work.

    I had a look around the parts express site and those filters come in more than just 20Hz. I noticed a 30, 50, 60, plus more but I better get back to work now........

    I wonder if something like this is available in Australia - probably not :(
  13. Again, I think the amp is clipping! This is typical behaviour. Only a badly setup phaser or flanger could produce this amount of subsonic rumble. My first head also had this flapping speaker characteristic. I added a 25 Hz subsonic filter (4th order Bessel IIRC) and it didn't do anything, only blurred up the low bass range due to phase issues because of the filter. I left it in the signal chains, just in case, though.

    You'd be surprised at how inaudible clipping can be. Even 25% THD is hard to make out when other musicians are also blasting away.
  14. Larry Kaye

    Larry Kaye Retailer: Schroeder Cabinets

    Mar 23, 2000
    Cleveland, OH
    I'm not anxious to solve another bass player's sound issues...he obviously doesn't give a rat's butt about it or thinks his stuff sounds "good enough" or even "great". I don't. My stuff sounds great as is.

    I'm just wondering whether you guys may have noticed extra speaker excursion, causing distortion or farting out the cab when you use a lower powered solid state or tube head that you had to turn up significantly to get the stage volume needed and then compared it to using a much higher powered head and had very little to no excursion yet much more volume without farting out.

    I'm sure all these filters may or may not make someone else's rig sound better or not in their ears. In my case, my Sunn 1200S, with Dod 31 band eq, monster cable bass and speaker cables, with either my G&L cheapo Tribute 5 or my F bass studio model, with either or an Epifani 212 old style 4 ohm cab alone, combined with a 4 ohm 2x8 from Low Down sound, or running 2 4 ohm low down sound cabinets, one with a tweeter, do not break up at any volume other than being way too loud in a fairly loud overall band stage volume, unless I am overdriving the preamp on the sunn which I don't have to do.

    Whereas if I used the GK 280 watt head or the traynor I mentioned into this Ampeg cabinet, it broke up, farted out and didn't have anywhere near the volume. I had the same issue with an extremely high quality Aguilar 359 head with two SWR goliath jr cabs that when the sunn was driving them again, had way too much volume before they even began to break up.

    I don't think this is a question of which of these four head has low pass filters to eliminate the sub sonic, non-audible, yet speaker bounce inducing low frequencies. I think it's because the head is underpowering the cabinet, GK...175 watts? into 8 ohm cabinet? Traynor probably about the same, Aguilar 359, 200 watts into cabinets that take 700? My sunn head with just the Epifani is running 800+ watts, the cab is a 700 watt cab, the Sunn is running 1200 watts with two four ohm cabs that combined are 1000 or 750 watt capacity speakers.

    It's reminescent of how much power an Acme takes...if you push them with lower powered heads, just like my Low Down Sound Cabs, they don't put out and a lotta unwanted crapola comes through the amp because it's turned up so high...MAYBE?

    My uneducated thoughts on the matter. I'm going to try to bring my sunn head to this gig. It puts out 500 watts at 8 ohms and if that's not enough to push this single 15 ampeg, maybe he needs to let me lend him my rig (for a price of course, like letting me play more at this jam session :rolleyes: )

    Thank you guys for putting up with my curiousity.

  15. K-Frog


    Feb 6, 2002
    Camden, AR, USA

    I sometimes use my Genz Benz GB12T alone with my AMP BH260.
    While it's a great little cab and head, I do get a bit too much speaker excursion when really pushing it.

    I used it once with my friends Kern IP-777 & QSC PLX 1602(bridged) and I couldn't believe how much the little cab seemed open up and speak with such clarity. Everything seemed much tighter, with less excursion.

    I don't know the science of it, but I think you gain more speaker control with more power. It may be the thing mentioned about less distortion.

    The guys that ask why headroom is important should be following this thread. I think my experience was a perfect example of why it's important.
  16. Larry Kaye

    Larry Kaye Retailer: Schroeder Cabinets

    Mar 23, 2000
    Cleveland, OH
    I'm glad to hear there's at least one other Talkbasser so far that has experienced what I'm talking about. Does anyone really think that the PLX power amp or the Kern preamp has these subsonic filters which miraculously transformed KFrog's Genz Benz?

    It's not like his AMP head doesn't sound good or is not loud enough in certain circumstances. It's just that a more powerful head that doesn't have to be turned up to get your best operating volume (headroom) for whatever reason gives you less cone excursion, allowing you to have more, un-farting volume out of the exact same speaker cabinet.

    Oh well, ranting over....I'd certainly like to hear from those interested in the "headroom" argument. What happens in a lower powered amp when you turn it that doesn't happen in a more powerful head that you don't have to push? I understand there's a % distortion in every head. I understand that some heads have a "cleaner" sound than others. I understand that if you clip your preamp or output stage, some bad stuff can happen. I understand that if you floor the low end tone controls on your amp or bass that the speaker's gonna bounce like all get out and break up much sooner, either due to overload on the speaker structure itself or by overloading your preamp or output stage.

    What I don't understand is why, like in my two hands-on, experiential examples, and now Kfrog's there's so much more stress on the speaker from excessive cone movement and signficantly less clean volume when you have to turn up a
    250 watt, for example, solid state or hybrid head but, at least in my case, there's no breakup and barely visible speaker cone movement. By the way, I also had the same experience with my EA 208's a while back. The cones on these puppies were poppin' and fartin' at a lesser volume with a Trace head I borrowed with 250 or 300 watts but I plug in my Sunn head with 900 or so watts, in the same room..ok?, it's clear as a bell, undistorted, unfartable, at a good 1.25 X the volume. As a matter of fact, I remember the sales clerk actually warning me to turn down (that was the only time that ever happened to me!!! at least in a store!! :smug: ).

    Thanks for listenin'

  17. alexclaber

    alexclaber Commercial User

    Jun 19, 2001
    Brighton, UK
    Director - Barefaced Ltd
    I don't think - I know. The PLX has switchable high pass filters, with either off, 30Hz or 50Hz settings.

    I think you've got a very good point though. I've done a few searches through google and noticed a number of references to "the high current requires to control the cone at high volumes" or words to that effect. If you think about the shape of the soundwave and thus the ideal movement of the cone, the highest rate of change of momentum is at the point of maximum excursion. As force=mass x acceleration = rate of change of momentum that means that the amp has to exert the greatest force on the speaker at that point.

    This is just conjecture, I'm at work and haven't the time to do the sums but I think:

    As the speaker moves outwards the voltage and current increase fairly linearly, until the wave reaches the peak at which point a substantial increase in current is required as the voltage starts to decrease and the cone is brought to a halt and then moved in the opoosite direction. If an amp is already working near its limits this extra current demand may be beyond its capabilities, hence the cone overruns its intended 'turnaround point' and may exceed Xmax.

    Does that make sense?

  18. Guys, read my friggin' comments!
  19. Larry Kaye

    Larry Kaye Retailer: Schroeder Cabinets

    Mar 23, 2000
    Cleveland, OH
    the amp clip light both on the preamp and output were not even close to on. I turned down the preamp per trying out the rig before we got started because it was distorting. When the tone was distorted because of overdriving the preamp, it was a totally different "looking" cone movement. Joris I'm not talking about pushing this cabinets volume capacity to it's limits at all. His Traynor with more power allows slightly more "useable" volume to come through, not necessarily sounding good you understand, than my GK, but I'll better dollars to donuts, that my Sunn head would push even more volume, clearer, without farting out the speaker than the other two...in this case...underpowered heads with less cone movement. It's not because there's some sorta filter on my head that I'm aware of...I mean, there's no switches...maybe built in? I don't think so...it's too cheap a head.

    Now the filter issue....the Traynor and Aguilar don't "have" separate filters that can be switched on and off like the PLX. Did Frog man have the 30 or 50 hz filter on and have that problem....we don't know because his Plx didn't HAVE THE PROBLEM with excessive speaker movement with the same smaller cabinet!!! Remember, the cabinet sounded more open and better than it did with his other head.

    Yes I read your post...but I don't think the heads are clipping on either pre amp or post side of the fence. I like the explanation that Alex gave but, being a total techically inept person, have only some idea of what he meant...BUT...maybe that's the reason that more powerful heads, filters or not, produce less speaker movement at the same or higher volume and I'll also say, TONE, levels than lesser powered amplifiers....generally speaking?

    What do you think?


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