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Thread: Trying to understand speakers

  1. #21
    Mojo's Minions
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    Default Re: Trying to understand speakers

    Quote Originally Posted by VinceT View Post
    My Mesa manuals say the opposite. “Safe mismatch” is when speaker load is greater than the output tap - so, you’d run a 16ohm cab off an 8ohm tap, or an 8ohm cab off a 4ohm tap.


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  2. #22
    Ultimate Tone Slacker Dave Locher's Avatar
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    Default Re: Trying to understand speakers

    Quote Originally Posted by LLL View Post
    To add: speakers are a hugely important part of your rig... YUUUUUGE.

    They are the final "EQ filter" when playing "live" (not mic'd up or DI'ing, etc).

    Speakers apply a hi and lo pass to your amp's signal; along with their own individual (per model) speaker "EQ".

    Change a speaker and your tone can drastically change even if you're using the exact same gear for the rest of your rig.
    Amen to that! I swapped my speakers a year or two ago and quickly went through 4 different models from two different companies before I came up with "better" (to my ears) than what I started with. Each change totally altered my sound even though they were all supposedly similar speakers.

  3. #23
    Ultimate Tone Slacker Coma's Avatar
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    Default Re: Trying to understand speakers

    Rather than start a new thread, Imma resurrect this one:

    How much of a difference in tone could one expect between playing with a matching cab vs a "safe mismatch" (cab impedance = 2x amp output impedance)?
    Last edited by Coma; 11-16-2019 at 02:28 AM.
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  4. #24
    A Ficus ehdwuld's Avatar
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    Default Re: Trying to understand speakers

    My Belair has a 4-8-16 switch
    It was on 4 and I mistakenly thought my 8 ohm speakers were 16 ohms each

    I moved the switch to 8 for the 4 ohm load

    The tone didn't change

    The amp wasn't hurt

    I did experiment a bit after I realized my mistake

    Single speaker at 8 ohm
    Both speakers in series 16 ohm
    Both speakers in parallel 4 ohm

    No change in tone
    Modest change in volume ( single speaker vs dual speakers )

    My Bugera G5 wants at least a 8 ohm load
    With a 16 ohm speaker
    And with an 8 ohm speaker
    There wasn't the anticipated volume drop
    But the difference in speakers was noticeable
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  5. #25
    of the Forum PFDarkside's Avatar
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    Default Re: Trying to understand speakers

    Quote Originally Posted by Coma View Post
    Rather than start a new thread, Imma resurrect this one:

    How much of a difference in tone could one expect between playing with a matching cab vs a "safe mismatch" (cab impedance = 2x amp output impedance)?
    I just want to point out that the so called “safe mismatch” only applies to Mesa and any other manufacturer that explicitly states this.

    Almost all the posts I read about this treat an amplifier like an ideal voltage source amplifier, where voltage stays constant and current is proportional to load impedance. This is true for solid state amplifiers, what we all learned in school, etc.

    Tube amps are closer to ideal current sources that will vary voltage with load. There are multiple taps on the output transformer to match the speaker load with the load that the tubes require. Also, if you are thinking it through, a transformer “reflects” the load impedance to the tubes. So as speaker impedance increases, the transformer reflects this as a smaller impedance to the output tubes. Either way, they are expecting a certain impedance, hence the various taps.

    As a final “gut check”, ask your self these two questions.
    1. On a solid state amp, what theoretical load is fatal? SHORT
    -For a solid state amp as you use smaller and smaller loads you are approaching a short, which is a failure condition.
    2. On a tube amp, what “load” is fatal? OPEN (we all are taught not to run a tube amp without a load)
    -For a tube amp, as you use larger and larger loads you are approaching theoretical Open.

    Depending on the output stage design and output transformer design/robustness, some level of mismatch may be ok, or it may not. That’s why I say check with the manufacturer. A doubling of impedance may be ok on a Mesa but not on a Bugera. At some mismatch it will cause damage, so verify what that “safe mismatch” is with the manufacturer.
    Last edited by PFDarkside; 11-18-2019 at 01:34 PM.
    Oh no.....


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  6. #26
    Ultimate Tone Slacker Coma's Avatar
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    Default Re: Trying to understand speakers

    I'm an idiot (again). After reading the manual for the amp in question, turns there is in fact the option of connecting a 16 ohm cab to it.

    Noticeable difference, would in this case be the answer to my question
    --------------------------------------------------------
    1973 Aria 551
    1984 Larrivee RS-4 w/ EMG SA/SA/89
    1989 Charvel 750 XL w/ DMZ Tone Zone & Air Norton
    1990's noname crap-o-caster plywood P/J Bass
    1991 Heartfield Elan III w/ DMZ mystery pups
    1995 Aria Pro II TA-65
    2001 Gibson Les Paul Gothic w/ PG-1 & SH-8

  7. #27
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    Default Re: Trying to understand speakers

    You also have to remember that amp output ratings are usually overstated---100 watts from a quartet of EL34 in Class AB is at max dissipation, which nobody designs into an amp.

  8. #28
    Mojo's Minions beaubrummels's Avatar
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    Default Re: Trying to understand speakers

    Quote Originally Posted by SoPhx View Post
    You also have to remember that amp output ratings are usually overstated---100 watts from a quartet of EL34 in Class AB is at max dissipation, which nobody designs into an amp.
    This isn’t entirely true. My old 1973 Traynor YBA 45-watt 2x 6CA7 and my buddies 1968 Park 50-watt 2x EL34 actually put out closer to 90 watts when dimed. My Traynor is louder than my HiWatt DR-103 100-watt. Newer 100-watt Marshalls that have an effects loop often put out no more than 80 watts.

    The 15-ohm vs 16-ohm discrepancy is due to the legacy 15-ohm rating used before speaker companies standardized on 16-ohm. Speaker impedance is really just a loose average because impedance actually varies by frequency of program material it’s reproducing.
    Quote Originally Posted by Demanic
    Incompetence is widespread in a world that rewards mediocrity while punishing excellence.
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    I am currently using Skullcandy headphones I found in the garbage.
    I did find the DS-1 in the garbage.
    I once found a guitar amp in the garbage, a Peavey Studio 110. It caught fire at the first gig I played it at.. But it was at the end of it, thank god.

  9. #29
    LoveMachineologist jeremy's Avatar
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    Default Re: Trying to understand speakers

    right, those numbers are "clean" power, when the amp is folding back on itself and roaring, at least the old ones are putting out a lot of power. ive blown 50w speakers with a 20w amp

  10. #30
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    Default Re: Trying to understand speakers

    Quote Originally Posted by Coma View Post
    Can anyone direct me to a good introductory source?
    All About Speakers

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