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HELP 210+115 bass enclosure problem. Maybe over-excursion?

Discussion in 'Amps and Cabs [BG]' started by TijlT, Jan 20, 2018.


  1. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    The LF version will take care of this. I noted in my original recommendation that the A version will tune ok but has a limited power handling capability for bass guitar use (but works nicely at lower power, say below 100-150 watts or so). The voicing is what can make the A version desirable in some lower powered applications.
     
  2. BadExample

    BadExample

    Jan 21, 2016
    Injiana
    Your cab might sound better and the 15 last longer if you get an HPF to filter out the lower frequencies that you probably don't want anyway. Very low frequencies are hard on amps, voice coils and eat up available power. You most likely can't hear the very low frequencies, but they will contribute to heat in the amp, VC and encourage over excursion issues.

    You mentioned is worsens at the lowest notes. This may be a clue that the 15 is getting too much very low frequency and suffering over-excursion as a result. An HPF could help, remove those very low freq's before the amp, then you have more power to use for what you want to hear. Large speakers are just not great at reproducing very low frequencies; they just have a hard time moving slow and far enough to reproduce very low freq. content.
     
    Stumbo likes this.
  3. How about some eq roll-off below 35-40 hz, just to test and confirm, if the OP has an eq available?
     
    BadExample likes this.
  4. TijlT

    TijlT

    Jan 20, 2018
    I never posted on here anymore because I didn't had a lot of time.
    Replaced the Delta 15A with the 15LF and the whole thing sounds amazing! It's crazy.. I really want to thank all of you who helped me with this build! I love playing the cab now at any volume! I did notice that some amps I tried it with. Like the Orange Bass 120 watt head. The volume had to go up much more compared with other cabs. Is this because the cab is 900 watts?
     
    HaphAsSard likes this.
  5. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    The sensitivity is lower with t he LF version, so you need to supply more power. This is one of the common trade-offs of higher power, but when you need the higher power handling there's no other option.
     
  6. Would that affect the Orange more than a SS amp?
     
  7. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Unlikely
     
  8. TijlT

    TijlT

    Jan 20, 2018
    Aaaaaand I'm back..
    The cab has a sound problem again. So at this moment it has this specs.

    - 2x10 chamber with 2x Eminence BP102 8ohm / is now 64,3L with speaker volume / 61,9L without speaker volume
    - 1x15 chamber with 1x Eminence Delta 15LFA 8 ohm / 140,4L with speaker volume / 136,8L without speaker volume
    - The 2x10 wired in series for a 16ohms circuit, this 16ohms circuit wired in parallel with the Delta 8ohms gives us a total of 5,3ohms or in reality measured at 4,2.
    - The ports are 4" and 160mm long. I remember @agedhorse told me they had to be 4" long (101,6mm)

    The cab hasn't been used for a month more or less. And now all of a sudden the Delta 15LFA sounds not ok.
    - To my opinion it sounds like soft over-excursion. But only sounds like it. I believe it can't be over-excursion because it happens literally at every volume in the same way.
    - A friend of mine his opinion is that it sounds like the cardboard could be ripped apart any moment.

    The cab has always been in a room with normal temperature and humidity.
    What is happening? The cab sounded beyond perfect with the modifications at any volume. It was even used on several live shows.

    Could the cause of my problem be the incorrect length of the ports? Maybe it has changed since the speakers are a bit more flexible now of using it.
     
  9. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Hold on, if it sounded fine when you put it away, it has to be something else... have you checked with another amp and speaker cable? Battery in your active bass? Start with the simplest and most likely things first.

    If you hear the sound of hoofbeats, don't go thinking it has to be zebras... it's more likely that it's horses.
     
    HaphAsSard and BadExample like this.
  10. Stumbo

    Stumbo Wherever you go, there you are. Supporting Member Commercial User

    Feb 11, 2008
    the Cali Intergalctic Mind Space
    Song Surgeon slow downer software- full 4 hour demo
    If everything else checks out, one or more of the speakers may have suffered over excursion or thermal over heating at your last gig and is now blown.
     
    Last edited: Jun 3, 2018
    BadExample likes this.
  11. TijlT

    TijlT

    Jan 20, 2018
    It's just weird. The sound comes only from the Delta 15LFA and that's a speaker with a Xlim of 16,5mm. The xmax is 4,8mm. Ofcourse it's difficult to see how much a speaker moves but i'm pretty sure it's not more than 5mm. I doubt it even got to 4,8..

    Tested with different amps, guitars and cables. All the same. The only thing now that is still incorrect on the cab is the ports length of 160mm instead of 100mm as calculated by @agedhorse.

    Anyone has another idea what could be the cause of this sound?

    I really appreciate all help since I have no idea what direction to go with this..
     
  12. BadExample

    BadExample

    Jan 21, 2016
    Injiana
    Could be a wiring problem, including wire rub on the cone or a flakey connection, or anything else rubbing the cone.

    Mechanical damage can begin anywhere between Xmax and Xlim. Xlim is where it crashes hard and usually kills it. You may have exceeded when you were playing last gig and not looking at it. Could also be thermal damage.

    Pull the wires off it and go directly to it alone, no other speaker, no crossover in circuit, and play quietly to determine if it's damaged. If it works well alone, it could be the crossover if there is one. If it sounds bad alone, try it out of cab very quietly. I usually stick a speaker to test out of cab in the corner of a cloth couch or wrap the back in a blanket to test out of box, then I feel save going above very quietly, sometime even above quietly, but I usually don't care so much if I toast one as long as I can get another.
     
    Stumbo likes this.
  13. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    This is why I am always conservative when it comes to claimed power handling. There are too many variables outside a player's control to be able to be confident of anything. The sensitivity of that driver isn't very high which makes it easier to push harder than you might expect. Tuning also affects (mechanical) power handling

    I think you will need to rule out other possible causes then focus on the speaker itself.
     
    BadExample likes this.
  14. TijlT

    TijlT

    Jan 20, 2018
    Okay I tried some more things.

    I think I'll need a HPF. But I don't know anything about filters.
    I used an online tone generator and played different frequencies with my laptop through my Ashdown EVO500 to the cab.

    When I set the whole EQ on the Ashdown to zero to get a pure signal, I can play close to 30Hz without any problem!

    After that I open up the bass EQ completely and it still sounds pretty good. (didn't try on higher volume now)

    But when I start adding sub to maybe 15% I can already see the VU meter make some very irregular movement together with a crackling noise.

    When I raise the sub even more the crackling noise is happening more often and louder (louder is logic since I gain the frequency I guess). This is all still on low volume and it sounds as the speaker can't take the sub frequencies.

    So I guess it makes that sound because of the frequencies below 42Hz and I need an HPF?

    Thanks for all the help so far!

    @agedhorse @BadExample
     
  15. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    It's possible that there is some protection circuit activating. I've lost track, but is your amp class AB/G/H?
     
  16. TijlT

    TijlT

    Jan 20, 2018
    Hi!

    I have found what the problem is, the cause and the solution! The only question I have left is HOW to create this solution.

    So I went to see someone here in Belgium that knows and has A LOT of experience with probably all amps and cabs there exist. I told him about my cab and about the weird sound it is producing, knowing that it sounded perfect before.

    According to him the 15" has been damaged by the use of synth. When the sound goes over the limit of 42Hz the speaker starts being damaged. He explained me that when you look at the sound curve of bass GUITAR, you'll notice that the waves go up and down constantly and very fast. So every time it hits the limit it goes down again and the speaker has time to 'cool down'.
    But with synth it happends a lot you play a low octave and hold it like this for some time (which gets easily below 42Hz). If you look at this sound curve the wave stays in one line hitting the limit of the speaker followed by overheating..

    Since the two 10" speakers are both 8ohms, 16ohms in series. And the 15" is 8ohms. The 15" is getting 2/3th of the amount of power and get's pushed even more.

    This means that the cabs would have kept working perfectly with only bass guitar. And I should have placed an HPF on the 15" to make sure everything under 42Hz is going back to the amp for the use of a synth.

    So now I need somebody's help with this HPF. I don't know anything about all of that. Where do I start, are these things you can buy pre fabricated or should I make this myself from scratch? What parameters are important to start?

    Thank you very much in advance!!
     
  17. Stumbo

    Stumbo Wherever you go, there you are. Supporting Member Commercial User

    Feb 11, 2008
    the Cali Intergalctic Mind Space
    Song Surgeon slow downer software- full 4 hour demo
    Contact [sfx]: high performance audio and have them modify their [sfx]:micro-thumpinator HPF to what you need.

    It's external so it works with whatever is plugged into it that goes to your amp.

    For more info, check out my HPF mega thread with the link below.
     
  18. TijlT

    TijlT

    Jan 20, 2018
    Thanks but I really want it to be internal!
     
  19. BadExample

    BadExample

    Jan 21, 2016
    Injiana
    You are wanting to put an HPF inside the cab to protect the speaker?

    It's much better to follow @Stumbo 's advice and remove the sub-audio harmonics before amplification. That conserves the precious wattage in the amplifier sections of your system.
     
    Stumbo likes this.
  20. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    A passive HPF inside a cabinet isn't going to work as you hope. Not even close.
     
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