1. Please take 30 seconds to register your free account to remove most ads, post topics, make friends, earn reward points at our store, and more!  
    TalkBass.com has been uniting the low end since 1998.  Join us! :)

Peavey MicroBASS replacement speaker possibilities?

Discussion in 'Amps and Cabs [BG]' started by scuzzy, Feb 17, 2017.

  1. scuzzy


    Feb 15, 2006
    Troy, MO
    I got an old silver fin Peavey Microbass amp, from the mid to late 80's in a sweet package deal. It sounds alright, but am curious what I could get out of it with a small speaker modernization. I was directed to winisd but it looked confusing to my simple mind.

    I am looking at an MCM mid range driver that is very affordable (sub $20). specs...an online calculator I found said this would work in a sealed or ported enclosure.

    Nominal Diameter:8 inch.
    Rated Lmpedance:4Ohm.
    Operating Bandwidth:60 ~ 6KHz (-3dB).
    Power Handling Capacity:70W RMS.
    Sensitivity (1W/M):89dB (±3dB).
    Voice Coil Diameter:1 inch.

    Thiele-Small Parameters:
    Resonance FrequencyFs:28.8Hz.
    DC ResistanceRe:3.4Ohm.
    Mechanical Q FactorQms:3.4.
    Electrical Q FactorQes:0.5226.
    Total Q FactorQts:0.4529.
    Equivalent Cas air loadVas:98.26 L.
    Surface Area of ConeSd:0.0216 m2.
    Efficiency Bandwidth ProductEBP55.1.
    Voice Coil Over HangX-max3.5 mm.

    And also at a slightly more expensive Faital driver, the 8FE200. specs are easy to find. Online calculator said this driver would work best in a ported cab.

    I feel I may be starting a fire storm. I know that speakers and cabs are matched, but have read of good results with putting quality modern drivers in these little combos. I'm not looking to shake the world, just sweeten up the tone and low end a bit. And if the speaker gets over $50, I would rather just buy a new combo. please keep that in mind. any and all direction is appreciated. even if that is rightly telling me the idea is stupid. :)
    Last edited: Feb 17, 2017
  2. Stumbo

    Stumbo Wherever you go, there you are. Commercial User

    Feb 11, 2008
    the Cali Intergalctic Mind Space
    Song Surgeon slow downer software- full 4 hour demo
    If you want to cleanup the tone of the Microbass cab or any cab you own, I suggest adding an HPF (high pass filter) like the one TBr fdeck produces.

    Not exactly what you were asking but something to consider.
  3. scuzzy


    Feb 15, 2006
    Troy, MO
    No one with speaker input?
  4. reddesert


    Mar 19, 2015
    I have one of those. It's a solid small practice amp. But with 20 W, an 8" speaker, and a small enclosure, I would guess it's hard to make it more than that. Not sure what the original speaker is like, but a very inexpensive speaker might not be much of an improvement. The MCM speaker isn't very efficient (low sensitivity number).

    If you want to try playing with speaker calculators, I entered your MCM speaker parameters and my guess at the Microbass cabinet volume into fdeck's online calculator, and the results are here: http://personalpages.tds.net/~fdeck...port=2.5&nPorts=1&endCorrect=0.732&PinExc=20&
    or http://tinyurl.com/z37dyrz . As you can see it rolls off a lot below 80-100 Hz. That's life with a small cab.

    I entered a sealed cab, but my Microbass is not actually sealed - there is a gap under the speaker baffle. You could try closing this gap or adding something to make a tuned port if you want to experiment.
  5. scuzzy


    Feb 15, 2006
    Troy, MO
    Thanks for your efforts! I'm not really looking for boom, but would like increased low frequency.... May not be possible in that lil cab.
  6. That little combo is undoubtedly well engineered for that price point. You can improve it some by increasing the budget. Improving the speaker can improve the tone provided the driver is compatible with the cab volume and tuning. Keep in mind that you are dealing with a 20w amplifier and an 8 inch driver. If you can provide the internal volume (or external dimensions and wood thickness, along with amplifier module dimensions), different drivers can be modeled. If you just want to try an inexpensive driver, consider this one from Parts Express: "TC-8034 8" Treated Paper Cone Woofer with Foam Surround 4 Ohm" from www.parts-express.com!. The specs look pretty good, although the sensitivity looks a little too good maybe... Another approach is to use a high quality 6 inch driver - The cab is basically a cube on the small side for an 8 inch driver. A 6 inch would have some breathing room. The Faital 6FE100 could be a good candidate. You may want to consider that this Peavey is nice for what it is, but is not a very strong upgrade platform.
    Last edited: Feb 20, 2017
  7. scuzzy


    Feb 15, 2006
    Troy, MO
    thank you for the information! that first speaker wouldn't be a big loss to try out, and if it isn't an improvement, no big deal. i certainly don't want to sink much into such a small inexpensive amp.
    AstroSonic likes this.
  8. wagdog

    wagdog Supporting Member

    Mar 20, 2000
    Waiting for the bus
    I used an Eminence Alpha 8a in a similar situation to good effect. It's efficiency is probably less than your stock speaker so you'll need to crank the volume more.

Share This Page