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More speaker with the same head equals what?

Discussion in 'Amp Central Station' started by waltschwarzkopf, Jul 10, 2018.

  1. waltschwarzkopf

    waltschwarzkopf Tele-Meister

    Age:
    33
    169
    May 17, 2017
    Zürich
    Hi guys,

    I was trying a Bassbreaker 15 the other day (awesome amp, by the way). I want it for home use, but I asked the guy at the store if it would be enough to take to the rehearsing room. He said maybe and when I asked if connecting another 1x12” speaker would help me, he said “it’s still 15 watts.”

    I understand that a 15 watt amp is fixed at that max power, but using a 1x8” cannot possible be the same as using a 4x12”, right? Especially if one gets to spread the sound all over the room, for example placing a 1x12” combo on one side and a 1x12” cab on the other. It may not be twice as loud, but I would certainly be louder and sound more even, right?

    I’ve always used combos or one-head plus one-cab combinations, so I don’t have any experience un bigger cabs nor on multiple cabs on one head. So any information and explanations that you could give me will be greatly appreciated!

    Cheers,
    Walter
     
  2. AxemanVR

    AxemanVR Tele-Afflicted Ad Free Member

    Dec 27, 2011
    Minnesota USA
    '
    That guy is an idiot...

    A larger speaker will be fuller, more dynamic and provide increased coverage.

    And yes, the perceived increase in loudness would be noticeable.

    That doesn't mean an 8" speaker can't sound good, but for how you plan to use it I'd definitely think a 12" speaker would be a significant improvement.

    Anyway, isn't it that guy's job to try and sell you stuff?

    '
     
    Last edited: Jul 10, 2018
  3. john_cribbin

    john_cribbin Tele-Afflicted

    Nov 26, 2014
    London
    More work for a chiropractor.
     
  4. waltschwarzkopf

    waltschwarzkopf Tele-Meister

    Age:
    33
    169
    May 17, 2017
    Zürich
    Yeah, instead he tried to sell me a different amp...

    The BB15 has a 12” speaker that sounds great and I think would be enough against a drum kit and the other guitar. But adding a 1x12” cab on the, would definitely an improvement in sound, volume and coverage, right?
     
  5. AxemanVR

    AxemanVR Tele-Afflicted Ad Free Member

    Dec 27, 2011
    Minnesota USA
    `
    Oh, I see, he was trying to push a more expensive amp then? Clever...

    Maybe he's not so dumb after all!

    But, yes, in my opinion the improvement you'd experience by going to a 12" speaker would be noticeable...


    `
     
    nojazzhere likes this.
  6. nojazzhere

    nojazzhere Friend of Leo's

    Age:
    66
    Feb 3, 2017
    Foat Wuth, Texas
    Let me guess....he wanted you to buy a Twin Reverb, right?.....Fifteen watts through one or two 12"s is plenty to hang with a band....unless you're playing WAY too loud. I have gigged with a Vox AC15, a Vox Pathfinder 15R into one 12", and my current Blues Junior III. If I needed more, it's the wrong gig for me.
     
  7. peteb

    peteb Friend of Leo's

    Apr 25, 2003
    Cascadia
    The guy is right it is still 15 Watts.



    What if the power were measured at two or four speakers instead of one?



    It could all be from a 15 watt amp, but the power out measured at the speaker would have to be more.

    Measurably more.





    Why hasn’t this been done?
     
  8. Tim G

    Tim G Tele-Meister

    219
    Apr 10, 2011
    johnstown
    Double the speakers, gain 3db. 1 12'" to 2 12" speakers, pick up 3db. 1 12" to 4 12", pickup 6db.
     
    Wyatt likes this.
  9. Wyatt

    Wyatt Tele-Afflicted

    Nov 3, 2004
    Tim beat me to this, I was typing as his reply posted.

    Thanks to the coupling effect, you gain +3db every time you double the number of speakers. This assumes all things are equal between the speakers; there are A LOT of real-world caveats that can reduce this...speaker size, speaker sensitivity, cabinet design; total secondary load; etc. But, if our speaker loads are correctly matched, and if our cabinets are equivalent, and if all our speakers are the same type...then a 15-watt amp into a 4x12 is as loud as a30-watt amp into a 2x12, which is as loud as a 60-watt amp into a 1x12 (at least, "on paper").
     
    waltschwarzkopf likes this.
  10. schmee

    schmee Friend of Leo's

    Jun 2, 2003
    northwest
    There is something about 1 vs 2 or vs 4 speakers for sure. It's almost like adding something like Reverb when you A/B them in the music room. A different fidelity.
    But at the gig, in the band mix.. most of that is gone.
     
  11. waltschwarzkopf

    waltschwarzkopf Tele-Meister

    Age:
    33
    169
    May 17, 2017
    Zürich
    Great! thanks for the reply. He was trying to push a Bassbreaker 18/30, which is a 2x12" with one channel on 18W and the other on 30W. Or a Hot Rod Deluxe IV, which is a 1x12" 40W IIRC.

    Either way, the Bassbreaker 007 has been my goal for a while and I recently saw the BB15 used for a good price (lower than a new or B-stock 007). So I went to A-B both of them. Sadly, the store that had both had sold one, so I could not try them side by side. I wanted the 007 because it was smaller and simpler, but thw 12" speaker on the BB15 sounds fuller and the gain structure selector really makes a difference. So I might go for that one. I'd use it mainly at home, but it would be nice to know that it would behave well in a studio room if I ever need to take it.
     
  12. AxemanVR

    AxemanVR Tele-Afflicted Ad Free Member

    Dec 27, 2011
    Minnesota USA
    `
    After giving it some thought, I have mixed feelings on which one you should choose...

    One of the best sounding amps I own is my little 5 watt "ChampTone" - a Fender Champion 600 based project I've been refining for the last year or so (details here):

    http://www.tdpri.com/threads/introducing-the-one-and-only-unofficial-fender-champtone-764.823203/

    I know what you're thinking, but I'm telling you that I finally got it dialed in and it sounds amazing! Plus, with the amount I spent on this project I could have bought a BassBreaker 007 and still had plenty of cash leftover!

    Anyway, my point is that the BassBreaker 007 may very well be what better suits your needs and, if you want to achieve sonic bliss at lower levels, a single ended tube amp can be hard to beat.

    I did notice that the BB007 combo comes with a 10" speaker, so you'll have to decide whether that will work for you (there's nothing wrong with a high quality 10" speaker fwiw). They also sell the head and a 12" external speaker cabinet separately, but that'd not only mean moving more stuff around but would no doubt cost a lot more too.

    On the other hand, 15 watts is pretty loud for home use if you plan to naturally overdrive it, since even a 7 watt tube amp can easily rattle the windows when cranked!

    As for me, I already own 15 and 30 watt amps, so having enough output for gigging is not an issue.

    As for you, I guess you'll just have to decide what's more important: lower wattage "usable" tone or higher wattage "just in case you need it" output...

    Good Luck!



    `
     
    Last edited: Jul 11, 2018
  13. peteb

    peteb Friend of Leo's

    Apr 25, 2003
    Cascadia
    I did a little test. Adding a speaker hurt the overall power out, probably due to the forced impedance mismatch.



    It was a flawed test. One 4 ohm speaker was replaced by two 4 ohm speakers in parallel changes the overall impedance by a factor of 1/2. In this case not for the better.



    A better test is replacing the one speaker with two speakers that present the same load as the single speaker.



    In my test adding the second speaker wreaked havoc on the signal voltage. In the power calc the voltage gets squared so it really hurts.





    Power = V*V/R


    My numbers



    One speaker - 4 ohm


    9W = 6V * 6V / 4 R = 36/4


    Two speakers - two 4 ohm speakers in parallel

    4.5 W = 3V*3V / 2 R = 9/2



    You lose a little power and you gain some dispersion.



    I would be concerned with a mismatch.
     
  14. Silverface

    Silverface Poster Extraordinaire Ad Free Member

    Age:
    66
    Mar 2, 2003
    Lawndale CA
    A 100% mismatch is no problem in nearly every Fender larger tweed, brown, BF, or SF amp The mismatch often has less effect on output level (from an audible basis) than speaker efficiency.

    There are websites that lay out the increase in db you'll get when adding speaker square inches (assuming no change in amp power and equal speaker efficiency).
     
  15. Wally

    Wally Telefied Ad Free Member

    Mar 17, 2003
    Lubbock, TX
    Walt, if you want to make the amp sound bigger, make sure that any speaker you choose is a high efficiency speaker.....100db or higher. The perceived volume of that amp could very well double. As Silverface notes, speaker efficiency is the most effective way of changing an amp’s volume in either direction....lower or higher.
     
  16. AxemanVR

    AxemanVR Tele-Afflicted Ad Free Member

    Dec 27, 2011
    Minnesota USA
    `
    I'd like to add that an impedance mismatch may not be a big factor in an amp's perceived output levels but still can change the character of the tone, for better or for worse, so that's at least worth keeping that in mind - not to mention that putting a speaker load lower than what the amp is rated for can definitely fry it...


    `
     
  17. Wally

    Wally Telefied Ad Free Member

    Mar 17, 2003
    Lubbock, TX
    IMHO, a 50% mismatch to the low side is much safer than a 100% mismatch to the high side with a tube amp. A mismatch to the high side introduces the possibility of flyback voltage damaging the OT secondary. The OT can continue to function but with degraded output power and sonic quality...depending on the damage. Some people play on such equipment without noticing the problem. A matched impedance is both more efficient and safer than either any mismatch.
    Running below the minimum impedance on a solid state amp will fry the output transistors in short order. Going higher than the minimum with a solid state amp is safe but decreases the power output drastically with each increase.
     
    Last edited: Jul 13, 2018
    AxemanVR and peteb like this.
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