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Speaker sensitivity and perceived volume

Discussion in 'Amps and Cabs [BG]' started by 46and2, Dec 6, 2017.

  1. 46and2


    Nov 12, 2017
    So having recently acquired a bass, I need an amp. I'm drawn to the light weight class D units for ease of moving, so I went to Guitar Center to check some out. I got to play a Rumble 500 2x10 combo and a PF500 head into a PF cab that appeared to be the 1x15 model. Volume wise, I was shocked that the Rumble seemed to destroy the PF. When set to the same level of master and gain, the Ampeg was noticeably quieter than the Fender. Is that due to speaker efficiency? Over or under rating power by the manufacturers? A defect in the Ampeg? I realize that there is more to the volume story than just numSpeakers(pi*r^2), but I'm at a loss to explain my experience. Tone-wise, I preferred the Fender but both were fine by me. They had some Markbass units too, but these are above my price range (looking at used units of 500+ watts).
  2. rickdog

    rickdog Gold Supporting Member

    Mar 27, 2010
    If "same level of master and gain" means the knobs were set to comparable positions, that alone explains the difference. There's no standardization of this, you can't assume that "same position" means "same gain".

    Try turning up the Ampeg master and gain... it might get pretty loud too!
    HolmeBass, MDBass, smogg and 7 others like this.
  3. 46and2


    Nov 12, 2017
    Fair enough. I assumed that 3:00 master and 12:00 gain on both would be comparable. I'll go back and try again another day.
  4. Al Kraft

    Al Kraft Supporting Member

    May 2, 2016
    Northern Virginia
    +1...normal variability in pots and differing tapers make comparisons like this impossible. One of the best heads I own (Mesa D-800) has linear taper pots that are 100% usable for every degree of rotation. This is a welcome oddity in the bass amp world, however, you'd think it was anemic compared to some other company's head where you have 95% of their full volume before you get to the volume knob to the noon position!

    Of course efficiency and honest usable power does play into the final equation, but my suspicion is that you were comparing knob positions and not true capabilities. FWIW, I think both Fender and Ampeg build nice gear...Markbass equipment, while fine if you like their voicing, tends to be a little on the pricey side with less stellar customer support. If I were going to spend Markbass level dollars I'd be sure to look at Mesa, Aguilar, GK, and some even higher end used gear (e.g. Bergantino, AudioKinesis, etc.).
    Last edited: Dec 6, 2017
    Korladis and Stumbo like this.
  5. 46and2


    Nov 12, 2017
    Appreciate the response, I'm not really that well versed on potentiometer tapering. I assumed, incorrectly it seems, that all amp manufacturers would use the same style of pot for controls.

    On another topic, I'd love a used Subway D-800 or MB800 head, but that would eat up my budget entirely. :(
    dukeorock likes this.
  6. Al Kraft

    Al Kraft Supporting Member

    May 2, 2016
    Northern Virginia
    As an aside, while we're on the topic, Tech 21 has even said on TB that the normal variability in the pots they see can make a difference in "tone vs knob position" from unit to unit on the production line.

    With budget as a concern, I think your focus on the Ampeg and Fender offerings will get you a lot of value for your money. I'd go back and try out some gear with your new found knowledge (which eliminates a concern you had) and see what strikes your fancy.

    Don't overlook well taken care of used gear either...a lot of folks buy new and find something doesn't work as well in a band situation as it did in the store, or they change bands and need new equipment, or they change musical styles and want a different sound, etc. There are some excellent bargains if you shop carefully.
    Korladis and dukeorock like this.
  7. dukeorock

    dukeorock Owner BNA Audio Supporting Member Commercial User

    Mar 8, 2011
    Nashville, TN
    Authorized greenboy designs builder/Owner of BNA Audio
    Used gear an option? There’s a great classifieds section here on TalkBass if you’re a supporting member.

    For the record, I think those Rumbles are pretty swell for the dough
    Inara, Aqualung60 and Al Kraft like this.
  8. 46and2


    Nov 12, 2017
    Used is the only way I can afford to buy, lol. I am not a supporting member, what does that entail exactly?
    dukeorock likes this.
  9. dukeorock

    dukeorock Owner BNA Audio Supporting Member Commercial User

    Mar 8, 2011
    Nashville, TN
    Authorized greenboy designs builder/Owner of BNA Audio
    A small donation to the site for maintenance and upkeep. You can then buy and sell here. I personally prefer doing here whenever possible. Had many great experiences with some terrific folks. They tend to be more honest in representing what they’re selling too.
  10. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Often, not even close.
    Inara, HolmeBass, Korladis and 2 others like this.
  11. popgadget

    popgadget Supporting Member Commercial User

    Sep 4, 2005
    Eastern, PA USA
    Authorized Greenboy Designs Builder, Scabbey Road
    Years ago I played through a Fender Bassman 400 2x10 combo, and it really surprised me. I’m not sure how available they are on the used market, but it would be worth looking into it.
    dukeorock likes this.
  12. Bim1959


    Apr 15, 2009
    Naples Florida
    Sales and electronic tech/piano tech: England Music Center - Clinton IA - now closed
    When did TB change things so you have to be a supporting member to buy? For a long time you only had to be supporting to sell but anyone could buy.
    The Nameless likes this.
  13. byacey


    May 16, 2008
    Alberta, Canada
    The numbers on the gain controls are just arbitrary numbers. Without knowing the amount of gain that the various stages in each amp are designed for, trying to compare knob indication numbers is meaningless.

    Now, if you were able to set the EQ flat, measure the output across the speaker terminals, and adjust the gains so they make the same output voltage with a repeatable input signal source, then you might be able to start a meaningful comparison between the two different speakers.

    I always got a kick out of listening to guys brag about their amps, things like "My amp has tons of power; look how loud it is with the volume control only set to 2." (What they neglect to understand is if they turned it up to 3, it might well run into clipping with a hot input signal.)
    basscapes, Korladis and agedhorse like this.
  14. dukeorock

    dukeorock Owner BNA Audio Supporting Member Commercial User

    Mar 8, 2011
    Nashville, TN
    Authorized greenboy designs builder/Owner of BNA Audio
    Maybe you can still, buy...sorry, didn’t mean to muddy the waters!
    46and2 and BadExample like this.
  15. BadExample


    Jan 21, 2016
    Any member can still buy. Can't buy or sell without membership at 666.com :D
  16. Korladis

    Korladis Banned Supporting Member

    Master and gain setting comparisons between different amps mean nothing.

    It's different between every amp.

    Also especially with cheaper gear, there is marketing incentive to make them seem to get loud early on the volume knob's rotation because it's more impressive in a music store environment. But often this means that there is no real volume difference between 12:00 and cranked.
    Al Kraft, Gearhead17 and agedhorse like this.
  17. seamonkey


    Aug 6, 2004
    Unless you really know amps, you can't really test an amp just in a store.
    Many retailers let you buy and try, return, swap after a few of trying it out in the real world.
    agedhorse likes this.
  18. ^This absolutely.

    The only thing the knobs tell you with any certainty is:
    All the way up, is all the way up.
    All the way down, is all the way down.

    Even if there are numbers, there is no calibration involved.
    You could even try two of the exact same amps set to 6 and one might be different than the other.

    I think a better ear test is, how loud can it get before you don't like how it sounds anymore.
    Korladis likes this.
  19. sawzalot

    sawzalot Supporting Member

    Oct 18, 2007
    Just play the one that is loud enough for you and sounds best. Don't even try to compare maximum volume levels. As long as both are loud enough, maximum volume is pretty much irrelevant.

    HolmeBass likes this.
  20. It's not just the difference in the pots and tapers - it's the difference in the preamp and power amp circuits themselves. And amps are *transfer functions* - they don't have an absolute output for a given setting, but rather they multiply the input signal by a certain amount at each amplification stage. So a louder input, say a bass with a hotter signal or running your bass through a clean boost pedal, will be louder for the same knob position on a given amp. Well, at least up the point that the amp's self-protection limiting kicks in, if you're really playing loud and pushing the amps.

    It would be pretty simple to compare the relative sensitivities of the Fender and Ampeg speaker cabinets. Using the same bass, with the same amp (either the Fender or the Ampeg), with the knobs everywhere the same, run the amp first through one speaker cabinet and then through the other. It is important to not change any settings on the amp or bass between using one cabinet and then the other. This allows a direct comparison of the sensitivity of the two cabinets. The louder one will be the more sensitive cabinet. This is because the only thing changing in this test is the speaker cabinet being used.

    If you think both cabinets are the same volume after conducting this test, then the one that sounds better is most probably slightly louder / slightly higher sensitivity. Not a 100% certainty, but often for things close in volume but slightly different our ears will prefer the louder one without necessarily perceiving it as louder.
    agedhorse likes this.

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