When is a 120w combo amp NOT 120w?

Discussion in 'Amps and Cabs [BG]' started by tubatodd, Mar 8, 2020.


  1. tubatodd

    tubatodd Supporting Member

    Oct 31, 2004
    Birmingham, AL
    ....when the cone installed is only 75w. Found this in my Hartke kickback 10.

    IMG_20200308_145402.jpg
     
    dralionux likes this.
  2. dralionux

    dralionux

    Feb 3, 2009
    Savannah, GA
    This is the stock driver of a Fender Rumble 100 v3
    Fender 100 v3 Stock Speaker Specs DG12-12-034-page-001.jpg
     
  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
    Actually, if you were to delve deeper into the way speakers are rated (specifically by Eminence), you might find that Eminence provides a "nominal" power rating that's not necessarily very close (or even reasonably close) to being accurate. It's up to the manufacturer of the end product to do their own testing to determine the actual power handling that they feel comfortable with for their specific application. Generally, I find that the ratings are higher than the real world results, especially when a HPF is incorporated into the amp, but in the case of the Fender driver being used, the testing that they do is pretty conservative compared with most. I also believe that there is a gap height error on that spec sheet and may not actually represent the production driver. Also, the power amp is 100 watts RMS at 8 ohms, no question about that.

    I wouldn't expect much different by Hartke either, the nominal "power number" is not the actual real world power rating. It's up to the manufacture of the end product to determine that.
     
  4. BogeyBass

    BogeyBass Inactive

    Sep 14, 2010
    a 120 watt amp is basically just that. 120 watts

    but bass unfortunately goes pretty deep.

    unfortunately the bad news is
    there is also " 250" watt or even" 350" watt speakers
    that will hit 10% distortion at only 80 to 120 watts

    its a rough ballgame for a speaker below 100hz

    as far as the hartke speaker
    looks like a stamp steel, with dam good sized magnet.
    probably a reinforced cone.

    looks like a fun driver, im not too shocked i know what one speaker or a single driver does with 100 watts.

    120 watts would be alot more than you think if you used 2x

    not the point
    a manufacture might have rated it for what it is. conservatively 75 watts
    as i said with typical 3m to 4mm drivers distortion gets up around 60 to 80 watts anyways.

    the actual voice coil could be good for " 150" to " 250" watts.


    just tell me what it does....oh 75 watts....cool
    ill take 8 of them lol

    their is also 300 watt or 500 watt combos.
    and it doesnt hurt my feelings. I already know the internal speaker
    cant handle all that power.
     
  5. PotsdamBass8

    PotsdamBass8 Supporting Member

    Jan 23, 2005
    Long Island, NY
    A Kickback 12 was my first amp, and I remember how much that speaker would move back and forth. I always felt like it was about to shoot through the grill if I hit too hard. It sounded great though.
     
  6. Yogi Bear

    Yogi Bear Supporting Member

    Aug 14, 2000
    When it's an old heavyweight Peavey from the 90s on back! I still have a TKO75, and have used it in the rare occasion for rehearsals and small jams. Noticeably louder than its rated 75w.
     
  7. ThisBass

    ThisBass

    Aug 29, 2012
    Germany
    You may want give the signal a crest number that equals 6dB and then you might be fine with even 150 Watt for the combo.
     
    agedhorse likes this.
  8. Raf Seibert

    Raf Seibert

    Dec 16, 2013
    Texas
    When is a 150W amp not a 150W amp? Whenever you’re not driving it to its fullest power. Just as your 150mph car isn’t doing 150mph while you’re driving around town, neither is your amp giving its maximum rated power all the time.
     
  9. JimChjones

    JimChjones

    Aug 6, 2017
    SE England
    Just in case you aren't aware, the power rating of a speaker is nothing to do with the actual amount of noise it delivers, its purely a measure of how much energy can be put into it before it breaks.

    A 12" 50w speaker and a 12" 500w speaker receiving 50w from an amplifier will deliver roughly the same volume. So provided it doesn't break, your 75w speaker will give you just as much volume in that amp as a 150w one would do. (Possibly a bit more if we went into subtleties I'm trying to avoid!)
     
    jamro217 likes this.
  10. Bassdirty

    Bassdirty

    Jul 23, 2010
    CT
    I think he meant 120W amp.. but still. ;)

    I think a better analogy would have been to use Horse power rather than top speed.

    Like, Your car is not delivering its "claimed" 310HP when you're starting from a stop sign. (under normal driving conditions ;)). More likey it'd be closer to *30 HP when starting from slowly from idle around *1500 RPMs. The 310HP would be after it revved up to say.. 5500 rpms. (* = or so/ish/roughly)

    Though, your point is still valid to an extent. :)

    I'm here to help.
    T$
     
  11. tubatodd

    tubatodd Supporting Member

    Oct 31, 2004
    Birmingham, AL
    OP here...

    So I guess what I was asking was really about what the numbers and the math mean. So the 120w is the rating of the head only. The cone rated at 75w tells me it can't handle the full load of the head. And the only way to get the full 120w load out of the head is to use a cab that can handle the full load.

    Is my understanding of these numbers correct?
     
  12. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    No. Re-read my post #3, I laid it all out there.
     
  13. tubatodd

    tubatodd Supporting Member

    Oct 31, 2004
    Birmingham, AL
    Re-reading post #3 as you suggested.

    <<It's up to the manufacturer of the end product to do their own testing to determine the actual power handling that they feel comfortable with for their specific application.>>

    So they labeled the head 120W and the same manufacturer labeled the cone as 75W. That's the part that confuses me.

    <<I wouldn't expect much different by Hartke either, the nominal "power number" is not the actual real world power rating. It's up to the manufacture of the end product to determine that>>

    Which numbers is that? The 120W or the 75W.

    I'm assuming Hartke makes their own cones. If they were sourcing them, then I totally get the potential mismatch.

    At the end of the day.........I like the amp. :) It punches well above its weight.
     
  14. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    The number on the part doesn't matter, it's a very nominal number. It's how the manufacturer applies the part that matters. For example, integrating an effective HPF into the combo might double the effective speaker's power handling.

    I agree that printing the number could be seen as confusing, unless you realize that it doesn't matter. If it didn't have a number on it, and it held up fine, would it bother you less?

    Understand that in the case of the Fender part, I know more than most about how Fender tests their products and IME they are both honest and conservative.
     
  15. tubatodd

    tubatodd Supporting Member

    Oct 31, 2004
    Birmingham, AL
    Thank you for providing clarity. I understand now.
     
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