210 Bass cabinet design with Eminence Deltalite 2510 II, overexcursion

Discussion in 'Amps and Cabs [BG]' started by TFM94, Aug 24, 2020.

  1. TFM94

    TFM94

    Aug 24, 2020
    Finland
    Hi everyone,



    I want to build a speaker cabinet for bass guitar. I have two Eminence Deltalite 2510 II drivers. Each can handle 250W, so they should be able to handle the 500W from my amplifier. So far, so good.

    I did some calculations in WinISD and with a cab volume of 56l and a tuning frequency of 60 Hz (using two ports), I can get a good response and port air velocity is also ok. The only concern is cone excursion, because at 500W I have up to 8mm excursion according to WinISD, which seems like a lot to me (x_max=4.1mm, x_lim=8mm). I usually play with less than half power, but I don't want to blow my speakers when I have to turn up the volume a little bit.

    I'm wondering where I'm going wrong. What parameter should I change to reduce con excursion? There are 2x10 bass cabinets on the market that can handle 500W or more, what are they doing differently?



    All ideas and suggestions are appreciated!
     
  2. You are up against the wall with the limitations of physics.
    ISD will let you play with the tuning frequency, which will shift the rapid rise in excursion below the tuning frequency.

    Find the lowest note you expect to play.
    Using the Excursion window, change the input power until you have reached Xmax at that frequency.
    You WILL be disappointed at how little input power is required to over excurse.

    Use more drivers.

    Power handling is a rating of the voice coil.
    It has nothing to do with cone excursion, and is really just a marketing gimmick to make the cab look impressive.
     
  3. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    Some drivers and some designs are capable of better (or more productive) use of available Xmax, everything is a trade-off when it comes to speaker design. As you can see, mechanical power handling limitations are a very significant challenge to successful speaker design.

    I suggest staying away from Xlim at all costs because that's an easy and quick way to ruin a driver.
     
    dkelley likes this.
  4. Your xmax number is the determining factor. Xlim is the limit mechanically the voice coil/spider can travel. IOW that's when it is banging off the back plate and/or ripping through the dust cap.

    Stay at or just below the xmax and your speakers will thank you.

    You'd be awfully surprised at just how loud these lil boogers will play with just a hundred watts.
     
    dkelley likes this.
  5. TFM94

    TFM94

    Aug 24, 2020
    Finland
    Thank you all for your kind replies. Although there is no "miracle solution", I can now move forward with the design. I just have to accept that I won't be blasting the full 500W through that 2x10. Is there any way to monitor the actual output power of an amp?

    If I ever have to use full power, I can always attach a second cabinet.

    Just a thought: If I wire my speakers up to be 16 Ohms instead of 4 Ohms (2x 8Ohm drivers), that would reduce my output power anyways (class D amp, it's rated for 500W @4 Ohm), so I wouldn't run the risk of applying 500W to my drivers anyway. How much power would my amp put out at 16 Ohm?
     
  6. My guess is around 150 clean watts for 16 ohms. That would be a little light but quite possibly sufficient for the 1 cab scenario.

    My Trace is around 160w at the 8 ohm mark and one 8 ohm 210 keeps up with non antisocial volume band.

    Btw. The frequency you tune for is not the fundamental of your lowest string. If we did that bass cabs would be three times the size and half as loud.
     
  7. There are ways to monitor output, but this is the most important - if it sounds bad, like distorting, turn it down.

    Theoretically, your amp would produce around 125 watts at 16 ohms. I'm not sure how your amp would take to a 16 ohm load. You should contact the manufacturer.

    A question - Is it too big a stretch for you to buy two more 2510's? You could build something really cool like a vertical 410 and bring it in at 8 ohms.
     
  8. TFM94

    TFM94

    Aug 24, 2020
    Finland
    The amp is a darkglass microtubes 500. I checked on the manufacturer website and it confirms that the amp can be used at 16 Ohm, but only has 125 Watts then. That could be enough for practice at home and jamming/band practice. I am thinking to make it switchable between 4/16 Ohms, so I can switch it to 4 Ohms when I need to (and then be careful with the volume knob).

    A 410 would be really cool, but impractical for me. I need to move it around between home, practice space and small gigs and a 410 is just to bulky and heavy for me, especially a vertical one. However, I might add a second 210 cab at some point.
     
    Last edited: Aug 24, 2020
  9. AlexanderB

    AlexanderB

    Feb 25, 2007
    Sweden
    I have used those drivers in a couple of 210 designs, and I definitely recommend you tune deeper than 60 Hz, based on calculations and many, many hours of using the different cabs on stage.
    If you do an EBS (extended bass shelf) tuning, you will get a cleaner, deeper, more articulate but "leaner" bass range. The response will start tapering off higher in frequency, but the roll off is smoother and less steep. Then you add back low end on the bass control, and elevate the "leaner" bottom end.
    The result is a box that goes deeper, with less cone excursion and more articulation. The downside is it needs additional eq and amplification output to compensate for the lower plateau bass range.
    With your amp, I think you have both the eq and grunt to make this work.

    Oh, how to do an EBS tuning? Basically tune your cab in the 45 Hz range instead. Look up EBS tuning online. By the way, make sure you have sufficient port area, and flared ports is nice, too. I would say a 3" tube per driver is the very minimum in your cab. 4" is better. I have used both, and the 3" will choke a little at really high SPL.

    I run my current Deltalite II 2510 2x10 cab with a LMII, and it goes really loud and deep with that amp, even with a fiver. With an inductor in series, one can tame the otherwise prominent spike in the 2 kHz range, and get a balanced and fairly honest sounding cab.
    Good luck!
     
    PawleeP, TFM94 and Doufuss like this.
  10. TFM94

    TFM94

    Aug 24, 2020
    Finland
    Thank you @AlexanderB for this super helpful post and greetings over to Sweden! It's great to hear from someone who has used these speakers in a similar setup. I think the LMII is a similarly powerful amp to the microtubes 500.

    I have to read a bit more about EBS tuning, but it sounds interesting. Power and EQ should not be a problem.

    Would you be willing to share your dimensions and parameters of your current 210 design (the one you use with the LMII)?
     
    Last edited: Aug 24, 2020
    AlexanderB likes this.
  11. BogeyBass

    BogeyBass Inactive

    Sep 14, 2010
    Pretty much, completely agree with @AlexanderB

    Reflex or ported cabs start to unload below Fb or port tuning frequency.
    Cone Excursion is very high below Fb.

    The graph might look pretty, and the -3dB response or F3 might seem lower with a higher tuning.
    But in reality higher tuning will reduce power handling. Since bass guitar can cover 30 to 40hz fundamental.
    High tunings in the 60hz range will cause the design to have low power handling.

    If the response goes flatter and lower tunings make the F3 appear higher, dont worry about it.
    Likewise if you noticed cone movement is restricted at Tuning frequency. Transients have inaccuracy when the cone is restricted and the port takes over.
    Better goal for a reflex bass cab for bass applications is to try and keep the reflex or tuning as low as possible. Keeps cone restriction away from bass fundamentals.

    Anyhoo. 2 things you can do.

    1. Tune lower in the 43 to 50 hz range
    2. Reduce cabinet volume for more power handling

    overall all Q will rise when you reduce volume, but with a lower tuning its less of a issue.

    try volume of .8 to .9 cubic feet per driver or 25.5 to 22.6 liters per driver

    Basically instead of using 56 liters try 51 to 46 liters and tune to 43 to 50 hz

    and yes there is no such thing as a 500 watt 2x10
    likewise reflex cabinets are still limited to the rise in resonant frequency much like a sealed cabinets. if you look at the 2 peaks in the impedance curve of a reflex cabinet. The first impedance rise is determined by cabinet volume. That is the end of the road. Second peak will change depending on tuning.
    Real world bass response with complicated waveforms in a ported cabinet is different than a modeling on a screen graph. Modeling gives insight on cabinet Q and cone excursion. Trying to milk more bass out of a pretty graph on a screen can be misleading. Hence you see typical high tuned reflex cabs, thinking F3 response is better.
    Keep the reflex low and away from bass fundamentals.
     
    Last edited: Aug 24, 2020
    AlexanderB likes this.
  12. AlexanderB

    AlexanderB

    Feb 25, 2007
    Sweden
    Thank you for the kind words - just glad I can help. I am currently very busy, but I might find some time later in this week to look at the data.
     
    TFM94 likes this.
  13. TFM94

    TFM94

    Aug 24, 2020
    Finland
    @AlexanderB I understand, take your time. I would really appreciate it if you could look up the dimensions and parameters.
     
  14. BogeyBass

    BogeyBass Inactive

    Sep 14, 2010
    EBS or Extended Bass Shelf

    Can be used for subs for extremely low tuning so you wont get unloading.

    But depending on drivers it can work, especially for 10" speakers with high Fs of 60 to 55hz.
    Ideal you use 12" or 15" speakers for a bass enclosure. Because Fs of those drivers is low around 45 to 35 hz and allows lower tuning.
    keeps unloading of the driver since tuning is low.

    But if you did want to use a 10" or any driver with a high Fs around 60hz

    Then EBS alignment can help. Since sometimes the actual volume is kept very small and helps with power handling, but tuning is set very very low below driver Fs. sometimes 20 to 30hz below.
    The response will form a " shelf" in the lowend
    Usually the shelf is -3 dB to -6dB below the rest of the speakers response.

    Hence the more common alignments EBS3 and EBS6 ( Extended Bass Shelf -3dB or -6dB)

    WinIsd will auto calculate these alignments its in the Menu

    Can be useful for subs too, since most subs are 20 to 30 hz Fs. So tuning 15 to 20 hz below Fs at 5 to 10 hz puts the relex unloading way way below most amplifier frequency range.
    Reduces the need for high pass filtering and the cone restriction that you get from a reflex enclosure works like a " brake"
    just takes ridiculous long port tubes to make it work with such low tuning.
    But in your cause a extended bass shelf in the 45 to 35 hz range doesn't need extremely long ports
     
    TFM94 likes this.
  15. BogeyBass

    BogeyBass Inactive

    Sep 14, 2010
    Below is transfer function Graph
    Yellow is your 56 litre 60hz Fb cab
    Red is proposed 47 litre 45hz Fb cab

    people would assume " more" bass from the yellow
    lets look below at cone excursion to see whats really happening

    TransFunc2510.png

    Below is cone Excursion at 100 watts
    As you can see as you near port tuning cone movement is limited, then further below tuning cone excursion increases dramatically
    Yellow Plot= from 50 to 70 hz very little cone movement. Most of the bass fundamentals will have poor transient. Cone is restricted
    Red Line= from 50 to 70 hz restriction is much less. Majority of bass fundamental is reproduced by the speaker.
    the transfer function graph leads to believe " more bass" from yellow. Reality Red Line has more bass and Transient , more power handling

    White marker is set to 40hz

    Yellow plot = 100 watts 40hz cone excursion is at 6.0 mm
    Red plot = 100 watts 40hz cone excursion is at 1.6 mm

    significant cone movement reduction at bass fundamental by reducing cabinet volume and lower 45hz tuning

    ConeExc2510.png

    Keep in mind ports and drivers take up volume in a cabinet.
    To actually get a 47 litre cabinet your internal volume would need to be around 52 litres to make up for the 3 to 5 litres of volume the drivers and ports displace
     
    Last edited: Aug 24, 2020
    Pulverizor likes this.
  16. TFM94

    TFM94

    Aug 24, 2020
    Finland
    Thank you for all the explanations about EBS. EBS sounds like a good choice. When I was thinking about excursion I was also looking at the peak above the tuning frequency, in your picture around 80-90 Hz, but I see that the excursion rise below the tunign frequency is just as important, especially with a 5 string.

    I ran a quick simulation in WinISD and naturally a lower tuning frequency requires longer ports. With a tuning of 45 Hz and two ports of 10 cm/4" I already have port lengths of 44 cm, that's already more than the cab is deep.
     
  17. BogeyBass

    BogeyBass Inactive

    Sep 14, 2010
    ahh, the fun of actually making numbers on a screen be real in life. lol

    This is the fun of designing a cabinet, and also remember to view port velocity at realistic power levels.

    Sometimes guys just hit max SPL and look at port velocity. in winisd it applies max power entered for driver data.
    so if you entered 250 watts your looking at yes 250 watts. So your 2x 10cm / 4" diameter port application was very good decision for velocity and correct way to do things.
    But...
    you discovered that larger ports require longer lengths and not enough room. this happens often in designs, especially for subs trying to reach 25 to 30hz tune.

    Anyways point is your looking at 150 to 180 watts of port velocity, and with nice round ports. Especially flared round ports. You can get away with higher velocity.
    Plus as mentioned, velocity is probably less at 150 watts. Plus, it is a old trick to make velocity little high. Adds more " port" sound and bass is somewhat perceived as being higher.
    Its basically what makes a ported cabinet appear to have more bass, the extra pressure from the ports. So you can have high velocity just not too high.
    Anyways blah blah , LOL

    just use smaller ports than 4" try 2x 3" or 8 / 7.6cm ports

    sometimes even 4x 3" ports yields good velocity. but shorter lengths
    or use 4x 2.5" ports, decent velocity but shorter lengths
     
  18. BogeyBass

    BogeyBass Inactive

    Sep 14, 2010
    Ideal air velocity rule of thumb is 17 meters per second
    but with flared round ports or flared ports, some feel you can go double to 34.
    Realistically id say I hear a distinct extra chuff or hum to the ports if you push 28 meters per second , with round ports with slight flare

    So your pretty safe in the 17 to 23 meters per second if trying to get away with small ports.
    like i said you can cheat a little for little extra boom or zoom around 20 to 25 with flares

    anyhoo with 2x 3" round ports at 9.3 inches length or 2x 7.6cm x 24cm
    port velocity is 17 meters per second at 36 hz and sneaks into 20 meters around 31hz
    with 120 watts. power handling above 100 hz is of course around 200 watts but the port doesn't work till ....45 hz
    technically the transfer function covers 30 to 80 hz ish. but anything coming out the port around 80 hz is more like leakage.
    sometimes ports that are too big, you hear the tone of the "box" in the room.
    so ports dont have to be too big and too small, but its why 150 watt to 250 watt cabs are somewhat easier to design for velocity.

    PortVel2510.png
     
    Last edited: Aug 24, 2020
  19. TFM94

    TFM94

    Aug 24, 2020
    Finland
    I found 3" ports that are flared on both sides, with two of them I could make a relatively short port (about 20-25cm) and still keep noise under control. Thank you for all the port suggestions.
     
  20. TFM94

    TFM94

    Aug 24, 2020
    Finland
    Btw, does it matter where the ports are attached to the cabinet (front, top, sides, back)? The tuning would still be the same, but is there a significant tonal change?