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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
    75% depth front to back. This means that there is space behind the sub-enclosure to take advantage of that cabinet volume that is otherwise wasted on the 10" drivers.

    Yes, you can keep the Delta 15. Is it the A version?

    You will need to pick 2 identical 10" drivers. Let us know your choices and maybe there is an obvious better choice.

    Belgium, this means that some options that I might otherwise suggest are not easily (or affordably) available to you.
     
  2. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Because IMO, there is a greater advantage to utilizing the available volume to extend the response of the 15" driver. The natural acoustic rolloff of the sealed 10" section may in fact be of benefit if we can manipulate the mid bass response acoustically. This will depend on the drivers he has available.

    It doesn't mean that you couldn't, but that there are some potential benefits with the sealed section.
     
  3. jhol111964

    jhol111964

    May 10, 2007
    Heart O' Dixie
    Still here, watching the drama unfold in full suspense, lol. More info:

    Are Ampeg SVT 410HLF's Eminence BP102s?

    http://www.eminence.com/pdf/Legend_BP102.pdf

    https://www.eminence.com/pdf/Delta_15A.pdf

    See if you find something interesting before you spend more money on more drivers.
     
  4. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    The BP-102 might be a good choice, but only if he can get a matching one in Belgium.

    The BP-102 and the Ampeg driver are not the same driver in spite of the suggestion that they are. If he has 2 of the Ampeg models, that might work too but without the parameters we don't know how well since I am recommending a sealed 210 section and these drivers were clearly optimized for ported applications. Good sealed cabinet performance is not an assumption that I am comfortable making because technically it would be nothing more than a wild ass guess (and I know enough about these drivers that it's not a good choice). The OP deserves better than that IMO.
     
  5. TijlT

    TijlT

    Jan 20, 2018
    @agedhorse
    @jhol111964

    So I tried to work out what I think you mean and with some extra useful bracing in the cab.
    What led me to this.
    2x10 chamber is now 64,3L with spkr vol / 61,9L without spkr vol.
    1x15 chamber 140,4L with speaker / 136,8L without
    1.PNG 2.PNG 3.PNG 4.PNG
    Or 3D te be viewed here: Autodesk Viewer | Free Online File Viewer

    Because you both having different opinions I’m getting a bit confused on what to do best now. What you see on the drawing above is easily to make for me!
    I can get more BP102’s, I can get another Ampeg speaker, I can get everything of Eminence, Celestion, Jensen and Warehouse if necessary.

    Oh and I asked Eminence for a data sheet of the Ampeg speaker (since Ampeg themselves do not have this information (kind of shocking but ok))
     
    Last edited: Jan 23, 2018
    agedhorse and Kro like this.
  6. jhol111964

    jhol111964

    May 10, 2007
    Heart O' Dixie
    We, me and Aged Horse really don't have different opinions on the fix - 3 others recommended dividing the chambers before I did, referenced other similar cabs with dividers, and Aged Horse chimed in after that with the same fix. I did recommend testing the drivers outside the cabinet to verify they aren't malfunctioning before investing in more construction, and checking for loose construction and cab buzzes first. I tend to order things from least to most in cost/labor, low hanging fruit first when troubleshooting.

    I like the vertical divider to stiffen the horizontal divider, but it may need to be vented between the 10" drivers, so they share the same chamber, like a 210 chamber. I might just try the horizontal divider first. At anyrate, if this doesn't work, I'd be back to thinking its something else.

    You might share that Ampeg data sheet when you get it, to confirm/deny the 10's are matches. The other thing in the data sheets that were interesting is that both drivers are stated as suitable for mixed driver applications, both are recommended for much larger cabinets that yours (don't need a lot of resistance), and the efficiencies are very different - 91 dB vs 100 dB. And the Delta has a low Xmax. Which leads me to another check: did you try it with and without the Delta connected? Same technique, try it with a single 10" connected?
     
    alaskaleftybass likes this.
  7. TijlT

    TijlT

    Jan 20, 2018
    I don't really understand what you mean with "I like the vertical divider to stiffen the horizontal divider, but it may need to be vented between the 10" drivers, so they share the same chamber, like a 210 chamber. I might just try the horizontal divider first. At anyrate, if this doesn't work, I'd be back to thinking its something else."

    The 2 10" speakers do share the same chamber ATM. The space between the back panel of the cab and the panel behind the 10's is air space for the 15".

    You can rotate my 3D drawing. I added a link to my previous post. Fyi, I did not draw the back panel of the cab so you'd be able to look inside the cab.

    Oh and.. received the data sheet!
     

    Attached Files:

    Last edited: Jan 23, 2018
  8. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Your drawing looks fine, I will look at the 15" tuning after I have my coffee.
     
    alaskaleftybass and Kro like this.
  9. BadExample

    BadExample

    Jan 21, 2016
    Injiana
    I've never attempted to match two different speakers together (without crossover), and certainly others can tell better than I can by the specs, but those two 10 inch speakers do not look like a good match to me. I think at least not in the same air space. If you can't get two matched 10's, I think you want the vertical divider to isolate those. The pdf doesn't have quite all of the information, but as an "OEM" speaker, it's nice to have any information at all. You should wait for confirmation by someone else though.
     
    alaskaleftybass likes this.
  10. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Ok, a little coffee and a little math shows what's going on.

    With the BP-102 drivers wired in series for a 16 ohm load, this section matches pretty well sensitivity-wise with the Delta 15 family (at 8 ohms).

    The cabinet with the changes shown tunes pretty acceptably with the Delta 15A using 2 x 4" diameter ports 4" deep, but remembering that this driver has limited linear excursion (it is fairly close to the EVM-15 in acoustic properties and the corresponding limitations) it is probably good for around 100-150 watts RMS mechanically. The high end is not ideal either because there is more voicing overlap with the BP-102 than I would be comfortable with (though it won't "hurt" anything". The Delta 15A is fairly sensitive to cabinet tuning, and would be equally sensitive to interactions with other dissimilar ("not-similar" for the benefit of Google Translate) drivers sharing the same air space. This could certainly explain why the OP was experiencing the symptoms he was.

    Now looking at this a little deeper, this is almost an ideal application for using a Delta 15LF version, the tuning would be the same (port area and depth), both drivers work well in this internal volume. The difference is that both the LF and HF response matches up quite well with the BP-102 pair. The phase response (roughly translated from the group delay) will possibly help the overall response and is of no practical effect below 40Hz anyway. This is what I would recommend, I think that it would work well without a crossover between the two sections, though I would experiment with reversing the polarity of the BP-102 section as this might improve the group delay over the section where it has the most impact without negatively impacting the balance of the response.

    This has the most likelihood of sounding pretty good, and has a real world power handling of around 250-maybe even 300 watts "RMS". Just be sure you wire the series pair correctly, positive of one driver to the negative of the other.
     
    HaphAsSard, guitarrophobe and Kro like this.
  11. Small problem. The first BP102 is a 4 ohm.
     
    alaskaleftybass likes this.
  12. BassmanPaul

    BassmanPaul Gold Supporting Member

    Aug 25, 2007
    Toronto Ontario Canada
    Ya just HAD to ruin it did’nt cha! LOL
     
    alaskaleftybass likes this.
  13. What's one more replacement driver in the scheme of rehashing dud cab into working cab?
     
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  14. jhol111964

    jhol111964

    May 10, 2007
    Heart O' Dixie
    Your iso looked to me, like you enclosed each 10". If the two 10" are sharing the same space, that concurs with what I and others were suggesting.

    PS - thanks for the datasheet. That was fast. Looking at the Xmax and net displacement of the 15 versus the two 10's, I wouldn't have thought there was an issue. I still think there are a couple other more likely causes I'd rule out first if it were mine.
     
    Last edited: Jan 23, 2018
  15. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    The standard BP102 is 8 ohms. Did I miss that he had the 4 ohm variant?
     
  16. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Running the numbers within any reasonable tunings, the Delta 15A has some big displacement limitations that the BP-102's do not have in a sealed enclosure. This is why I could never use the Delta line for bass unless I was willing to accept these limitations in exchange for the mid voicing. The production market would not accept this trade-off IME. The LF variant is a very different driver.
     
  17. That's what I got from the OP. Non identical twin 4 ohm series of tens in series, parallel with the 8 ohm 15, for a 4 ohm total.
     
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  18. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Yeah, I see that now, but read right over it because normally the 4 & 16 ohm variants are special order and are likely not readily available in Belgium.

    In this case, I would suggest 2 of the standard BP102's in 8 ohm.
     
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  19. TijlT

    TijlT

    Jan 20, 2018
    Lucky me, I have two BP102 - 8ohm's laying around somewhere around here! But.. ain't I getting a 12ohm total then? By doing 2x8ohm in series, parallel with the 15" at 8ohm.. The SVT Classic has only an output of 2 or 4ohms. Or what am I missing here?
     
  20. 16 ohm parallel with 8 ohm is 5.3 ohms.
     
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