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Thread: SS amp load question

  1. #1
    daz
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    SS amp load question

    I have a 1x12 modeler combo that is 4 ohms nominal and i have 2 different 8 ohm speakers and i have tried the combo with both of the 8 ohm speakers by themselves and then i tried combining them using a parallel jack i added with a 1x12 ext cab. What i noticed is that the amp sounds very noticably darker at 8 ohms than 4. In other words, if i use either one of the 8 ohm speakers by itself whether in the ext cab or in the combo, the sound is dark. Soon as i plug the other one in parallel with it and then have a 4 ohm load, the tone gets a lot brighter. And this happens even after adjusting the master to compensate for the slight volume difference. By the way, the speakers are a EV12L and a celestion G12T-100. The stock 4 ohm by itself is bright to a fault so i can't use that to judge how the others would sound by themselves if they were 4.

    The reason i posted this is i want to get a 4 ohm speaker for the amp so i can use it without the ext cab and not lose that top end. But i'm a bit worried because the speaker i want to use is an EV and they don't make them in 4 ohm. But there are a few EV clones that will custom make one for you in 4. Problem is they are very costly and if it doesn't do what i need it to i'm out big $ because 4 ohm speakers are VERY hard to find a buyer for, especially for such an expensive speaker. So i wanted to see what some of you have to say about the difference in tone i get with those 2 8 ohm speakers at 4 ohm vs either one of them at 8. Why does 8 ohms make them sound so dull compared to when they are combined? And yes, they are in phase. Common sense tells me a 4 ohm speaker will sound bright to it;s normal potential but i can't be sure of that because i'm not sure if a higher then optimal load is whats causing this in the first place. Is it normal or if not why does this happen?

  2. #2
    g1
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    Sounds very odd for a modeler. Even being sure they are in phase, I would try putting one out of phase and see if it gets worse.
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  3. #3
    daz
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    Quote Originally Posted by g1 View Post
    Sounds very odd for a modeler. Even being sure they are in phase, I would try putting one out of phase and see if it gets worse.

    Made a quick 1/4" male=female adapter with male tip to female ground. Just got real anemic as would be expected. I wonder if somehow there could be some sort of acoustic phase thing that can happen between 2 speakers acoustically if thier freq curves are such that they could cause that.

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    Which modeling amp is it? Is it possible that the amp changes cabinet model when you plug in two speakers? I know that on my Line6 AX2 it will turn off the cabinet model to the speakers when you put a cord into the line out jack (because it then applies a different model to the lineout) which is weird but that is the way it is.
    g1 likes this.

  5. #5
    Old Timer J M Fahey's Avatar
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    Quote Originally Posted by daz View Post
    1x12 modeler combo that is 4 ohms nominal ... 2 different 8 ohm speakers ... tried the combo with both of the 8 ohm speakers by themselves and then i tried combining them using a parallel jack i added with a 1x12 ext cab. ..... if i use either one of the 8 ohm speakers by itself whether in the ext cab or in the combo, the sound is dark. Soon as i plug the other one in parallel with it and then have a 4 ohm load, the tone gets a lot brighter...... the speakers are a EV12L and a celestion G12T-100........ The stock 4 ohm by itself is bright
    So we are talking three speakers here?
    The 4 ohm original one and 2 different 8 ohm, an EVM12L and a Celestion G12-T100?
    Please tell us what amp it is (brand and model and even better if somebody posts the schematic) , a "mystery original speaker" picture, both front (to see cone) and back (to see magnet) can help.
    Does it have a barcode (or plain factory code strip) glued to themagnet on the side?
    Eminence makes most of them and usually labels them so for internal warehouse or stock control, might help.
    And this happens even after adjusting the master to compensate for the slight volume difference.
    You keep the suspense running
    Suppose you play with one speaker, then touching nothing just add a second one in parallel .... you speak of a "difference" , but ..... which way?
    Does overall volume rise when second added or go down?
    The reason i posted this is i want to get a 4 ohm speaker for the amp so i can use it without the ext cab and not lose that top end.
    Unless I understood you very wrong, you already have such a speaker ... the original one.
    But i'm a bit worried because the speaker i want to use is an EV and they don't make them in 4 ohm.
    Any reason for that?
    You just stated that you donīt like it in 8 ohms .... fwiw and for any speaker the 4 ohm version is duller than the 8 ohm one (voice coil is heavier and sometimes the gap must be wider to accomodate thicker wire, a second dulling factor) so I guess you will like it even less.
    Problem is they are very costly and if it doesn't do what i need it to i'm out big $ because 4 ohm speakers are VERY hard to find a buyer for, especially for such an expensive speaker. So i wanted to see what some of you have to say about the difference in tone i get with those 2 8 ohm speakers at 4 ohm vs either one of them at 8. Why does 8 ohms make them sound so dull compared to when they are combined?
    But you donīt have an ohms problem , in which you would still like at least one of the 8 ohm ones, all you might lose is some volume but tone should not change. (or change minimally).

    And yes, they are in phase.
    Don't trusrt labels but test them with a battery, sh*t happens or you might be "looking" at an error but not "seeing" it, not the same.
    Happens all the time.
    Some call it brainfart but nevermind the label, it happens all the time to everybody so just re re re recheck.
    Common sense tells me a 4 ohm speaker will sound bright
    sometimes common sense does not apply.
    to it;s normal potential but i can't be sure of that because i'm not sure if a higher then optimal load is whats causing this in the first place. Is it normal or if not why does this happen?
    Normal? .... dunno.
    Weird? .... in spades.
    Why? not sure yet but testing may help.

    Something that is nagging me: HOW did you add that parallel extension jack?
    Is it a plastic or a metallic jack?
    WHERE does its ground terminal go? .... to chassis / power supply ground / original - terminal touching nothing else?
    Notice that these 3 points I mention are completely different

    IF that amp, as I guess, has some complex/mixed feedback network and you connected extension speaker to chassis or supply ground, then you bypassed/killed it and sound/volume *must* change, go figure.
    Juan Manuel Fahey

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    Old Timer olddawg's Avatar
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    What happens when you use one 8 ohm speaker and parallel an 8 ohm resistor across it?

  7. #7
    daz
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    Quote Originally Posted by olddawg View Post
    What happens when you use one 8 ohm speaker and parallel an 8 ohm resistor across it?
    I don't have one other than 1/2 watt or less.

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