Speaker cables and reversing the wires

Discussion in 'Amps and Cabs' started by glogulus, Jun 18, 2005.

  1. glogulus

    glogulus Supporting Member

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    I recently found out that my two rock amp (well all of the TRs that have the active efx loop I think) wants to use a reverse wired speaker cable when going to a non-two rock cab. I was wondering why this was, and what other amps might need this type of setup.

    Right now my two rock and bogner cab seem to be playing well together with a normal wired cable, and I'm wondering how much improvement I will hear when using a reversed cable... This may be the reason why my TR cab sounded louder and fuller then my bogner cab on similar volume settings.
     
  2. drbob1

    drbob1 Silver Supporting Member

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    I don't know why, but I do know the result. If you have a regular cable, plugged into a regular speaker (AFAIK speakers like the vintage Jensens and vintage Celestions are wired opposite each other) you're going to lose a little "pop" on the notes because the speaker starts by sucking in on the note attack. Put a second cabinet wired normally beside the one wired wierd and they'll be out of phase and sound weak together. You can check this out by using a 9v battery (a tired one, please) and seeing which way the cones go in the two cabs when applied to the end of a speaker cable. If it's the same way, no problem using them together.
     
  3. glogulus

    glogulus Supporting Member

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    I still wonder why it is even necessary to wire stuff weird.
     
  4. aleclee

    aleclee TGP Tech Wrangler Staff Member

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    In many cases, it's a result of having an odd number of gain stages, each of which reverses the phase of the signal.
     
  5. aeolian

    aeolian Member

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    Huge thread awhile back on this. Even Steve Kimock (who's a proponent of doing this) jumped in.

    Emotions ran almost as high as a Dumble/Zoosh thread though.
     
  6. scottl

    scottl Member

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    Glogulus,

    The Two Rock amps, with built in tube loop, output a reverse phase signal. So do the Fuchs amps for that matter. Two Rock reverse wires their cabs for optimal performance with their heads for the reason that was described here. In my case, I have reverse wired cables I use that bring my cabs into absolute phase. That way everything stays uniform.

    Fwiw, you can and do here the absolute phase issue. It is more or less dramatic depending on cab and speaker type.

    Scott
     
  7. glogulus

    glogulus Supporting Member

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    I forgot to mention that I am going to get a reverse wound speaker cable, I was just asking the question as to why it happens. I think that comment about the even/odd gain stages probably makes the most sense to me.

    Well, I wouldn't want to start any hot debates so, I'll just be happy that my amp will probably sound "better" with the right cable :).
     
  8. scottl

    scottl Member

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    Glogulus,

    In our amps the clean tube, V1, inverts twice. The output to the dirty channel is in phase. The next tube, V2, does the same. So, whether you are on the clean or the dirty channel, things are in phase heading to the tube buffered loop. Here is the rub. The loop is half cathode follower (no phase flip) and half gain stage. The return amp gain stage of the loop flips the phase. Things are out of phase at this point. Next is the phase inverter. As the name suggests, the phase is flipped one time. Things are in phase going to the output tubes. The output flips phase one last time. The result is an out of absolute phase signal at the speaker jack. This is fact. Whatever signal is plugged into the amp will be the opposite coming out. Fact.

    My opinion is that speakers sound better pushing out before sucking in. You need to try the cable to see which way you like most.

    Scott
     
  9. glogulus

    glogulus Supporting Member

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    Thanks for the info Scott. A lot of that was over my head, I guess it comes down to try it both ways and see which way I like it better :).

    Btw, I just put in some 1k5w resistors so I can use EL34s and as long as nothing blew up when I was playing it probably means I got them in right, right?
     
  10. VaughnC

    VaughnC Supporting Member

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    For a speaker to move foreward on the initial guitar attack, the guitar used would also enter into the equation too because not all guitars have the same initial attack voltage polarity.
     
  11. scottl

    scottl Member

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    Maybe so, but I believe a normally wired humbucker axe is "in phase" with an "in phase" amp. At least mine are.

    Doesn't change the fact that the amp is out of phase as a matter of certainty. My suggestion is have an in phase amp using the reversing cable and then work from there with your ear.

    Too many people (not you Vaughn) like to try and poopoo the concept. It is fact. This particular amp topography outputs an inverted signal. Not arguable. What you need is a reversing cable and ears to test it on your own.

    Scott
     
  12. Tom CT

    Tom CT Old Supporting Member Gold Supporting Member

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    When Two Rock builds their amp heads, why don't they just reverse the internal connections to the speaker jacks in the first place? No one would have to be concerned with custom speaker cables, and there would be no more battery tests or other confusion to deal with.
     
  13. VaughnC

    VaughnC Supporting Member

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    Agreed....I believe that a speaker moving forward on the initial attack is an important issue. The point I'm trying to make is that if you play guitars made by different manufacturerers, you may have mixed results. However, not being an expert on humbuckers, I wouldn't assume that ALL humbuckers by ALL manufacturers are the same polarity (I think PRS is opposite polarity of Gibson). But I do know that Fender has changed their Strat pickup magnet polarity a few times over the years which, of course, would change the voltage output polarity (if wound the same direction).

    Also, if you use any pedals between your guitar & amp, there's another possibility for signal polarity reversal.

    Like you said though, it doesn't hurt to try reversing the speaker phase and let your ears be the judge. I ran into a similar issue a few years ago with input cables. I never would have believed it (until I tried for myself) but some of my input cables sound different just by reversing their direction. If you can't hear the differences in these types of things though, count your blessings and "plug & play". But I find it interesting to play with these types of things just to see the end result.
     
  14. tonedaddy

    tonedaddy Member

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  15. fullerplast

    fullerplast Senior Member

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    I mentioned this in the other thread, but I'll mention it again here; you can add an inversion anywhere in the path. An easy way to do this is with an inverting buffer like a BS-2. It will allow you to do a quick A/B rather than swapping out cables. You can also accomodate dual channel amps with different numbers of stages if you want to. Keep in mind that Fender reverb amps will have an extra inversion in the reverb channel that is not in the normal channel as well.

    I actually had a hard time convincing myself that there was anything to the concept until I tried it for myself. Personally, I noticed a difference with some amps and very little difference with others. It's more noticeable at volumes that allow guitar-amp feedback to occur. I think it is a real phenomenon, but I'm not losing too much sleep over it.
     
  16. John Phillips

    John Phillips Member

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    That is true, but the most important inversion is the one after the amp IMO - if it's distorting - because amp distortion (especially preamp based) is quite often asymetrical. Irrespective of the phase or symetry of the input signal, the output waveform can end up 'directional' in the same direction. On a clean sound, it should matter less (or not at all) where you flip the phase, because the largest asymetry is in the attack portion, which is present all the way from the guitar.

    I agree with both those things.
     
  17. fullerplast

    fullerplast Senior Member

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    Well, I'll agree that amp distortion at various stage can and will be asymmetrical, but I can't put a degree of importance on any particular placement of an inversion without hearing and comparing the results. It's a difficult thing to figure which will sound better from an analytical standpoint IMHO.
     
  18. glogulus

    glogulus Supporting Member

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    Well, I've got a reverse wired cable on order. I'll post what happens when I get the cable.
     
  19. glogulus

    glogulus Supporting Member

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    I just had another thought.. If two rock cabs come reverse wired already. Do you want/need to use a reverse wired cable when using the cab with a non-two rock head? Or, is this another situation where testing/hearing the difference is applicable?

    I've got a two rock cab that I may keep if this makes a diff :).
     
  20. Strung Up

    Strung Up Member

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    So, I've got a Two Rock, and I often point my cab at the wall next to the drummer in small places . . . so I guess I should reverse the cable twice!

    Wonder whether it'll sound better if I reverse it twice at one end or once at both ends?

    :p
     

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