Replacement speaker for bass combo.

Discussion in 'Amps and Cabs [BG]' started by BoogerMan79, May 30, 2018.


  1. BoogerMan79

    BoogerMan79

    Apr 7, 2017
    Texas
    Have an older 100 watt 15" combo that needs the speaker replaced. The stock speaker was a 4 ohm. Was looking for suggestions for best replacement options. Thanks
     
  2. jcerio

    jcerio Supporting Member

    Jul 27, 2006
    Syracuse, NY
    What's the make sand model of the combo? Is there any information on the speaker itself? If you can't get a replacement from the combo manufacturer or on Ebay I'd suggest calling a reputable speaker maker like Eminence and ask them for their advice. This may help you get a speaker that has a chance of sounding good in your particular cabinet.
     
  3. BoogerMan79

    BoogerMan79

    Apr 7, 2017
    Texas
    The combo is an old Randall RB100. The amp is rated 60 watts to 8 ohms or 100 watts to 4 ohms.
     
  4. jcerio

    jcerio Supporting Member

    Jul 27, 2006
    Syracuse, NY
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  5. BoogerMan79

    BoogerMan79

    Apr 7, 2017
    Texas
    Thanks. I tried to contact Randall with no luck so I emailed Eminence and they suggested a speaker that would work for the amp. The Legend CA154. Has anyone had any experience with this speaker?
    Speaker Detail | Eminence Speaker
     
  6. There was an early version with a 15 inch driver in a sealed cab, and a later version with a 15 and piezo horn (had a graphic EQ) that was ported. Which version do you have? Both have about 2 cf internal volume. If you have the ported version, what is the port depth? Do you prefer an old school tone (minimal treble) or do you like some highs?
     
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  7. BoogerMan79

    BoogerMan79

    Apr 7, 2017
    Texas
    This is the early sealed cab version. I do like some highs. Versatility in the tone.
     
  8. The short answer is the Eminence Beta15a. It's specs make it well suited to use in a compact, sealed cab. It has nice presence in the upper mids and lower highs. It IS an 8 ohm driver, but the lost power (relative to 4 ohms) amounts to only about 2 db - many people would not notice the difference.

    An alternative is the Jensen MOD15-200-4. It's tone is similar to the Beta, but it is more sensitive, and has a touch more upper mids/lower highs presence. And its a 4 ohm driver (actually available in 4, 8 and 16 ohms). The trade-off is less linear excursion, but this is unlikely to be an issue with your combo.

    The Eminence CA154 is well suited to sealed cab operation, but has less presence and high end extension. Compared to the Beta and the Jensen it will sound a little dark.

    If you go with an 8 ohm driver you could add a jack plate and be able to use an external 8 ohm cab.

    Decisions, decisions...
     
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  9. BoogerMan79

    BoogerMan79

    Apr 7, 2017
    Texas
    If you go with an 8 ohm driver you could add a jack plate and be able to use an external 8 ohm cab.

    Decisions, decisions...[/QUOTE]

    The amp has separate outputs for 4 ohm and 8 ohm. I had thought of possibly using an extension cab in the future. I'm quite ignorant about all this.
     
  10. The manual doesn't really cover this (or much else), but the amplifier is not likely to be 2 ohm stable (two 4 ohm drivers/cabs in parallel). I would just choose a driver an impedance that is no lower than the stock driver. An 8 ohm driver is a safe choice. With only about 2 db less sound (60w vs 100w), an 8 ohm driver like the Beta or Jensen will be at least as loud as the stock driver (maybe louder) due to their higher sensitivity. Two of them in parallel (4 ohms total) will allow the amp to produce its rated 100w. Not sure how the 4 ohm jack works, but wouldn't be surprised if it wired the 4 ohm extension speaker in series (preventing a 2 ohm load).
     
  11. BoogerMan79

    BoogerMan79

    Apr 7, 2017
    Texas
    The stock driver was plugged into the 4 ohm jack.
     
  12. BoogerMan79

    BoogerMan79

    Apr 7, 2017
    Texas
    If I went with an 8 ohm driver it should be plugged into the 8 ohm jack then, right? Like I said, totally ignorant.
     
  13. Well, if that were the case (you plugged your new 8 ohm driver into the 8 ohm jack), then any new external cab would have to be 4 ohm and plugged into the 4 ohm jack. Most solid state amps work into a range of impedances, like 4-8 ohms, and any combination of cabs with a total impedance in that range will work. Some will have the external scab jack labeled 8 ohms because the internal speaker is an 8 ohm driver, and the total (wired in parallel) is 4 ohms, which is the lowest impedance the amplifier is designed for. Honestly, I would measure continuity between the two jacks to see if they are simply in parallel (plus to plus and minus to minus). This could also be seen visually, if there is a jack plate that can be removed. If the jacks are in parallel, I would just ignore the impedance markings and just plug in.
     
  14. BoogerMan79

    BoogerMan79

    Apr 7, 2017
    Texas
    Upon further inspection both speaker jacks are marked 8 ohm so it wouldn't matter.
     

    Attached Files:

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  15. BadExample

    BadExample

    Jan 21, 2016
    Injiana
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  16. BadExample

    BadExample

    Jan 21, 2016
    Injiana
    Never mind :D
     
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  17. So it sounds like the new internal driver should have an 8 ohm impedance. Also, any external cab you connect.
     
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  18. BoogerMan79

    BoogerMan79

    Apr 7, 2017
    Texas
    Sounds like it. Thanks for the help. I seriously need to learn more about this stuff.
     
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  19. Check out the Amps FAQ in this forum for a players guide to impedance, power ratings, bass drivers and cab design (among other topics). Not enough info to design and build this stuff, but enough to make informed decisions and know when to ask for help. Far and away, your time is best spent playing music. :)
     
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  20. BoogerMan79

    BoogerMan79

    Apr 7, 2017
    Texas
    Agreed 100% Ordered the speaker for the amp. As soon as it get here I'll get it installed and be back jammin.
     
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