Correct Red/black Wire Inside Cabs

Discussion in 'Let's Talk Vintage' started by MikeyV, Oct 8, 2018.

  1. MikeyV

    MikeyV New Member

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    I have a '73 cab that's had it's original wire spripped. I have a matching date greyback (matches the three original dated KF23) and plan to take all those screws off only once!

    Can someone tell me the gauge and other characteristics of the original wire?
    I do have a matching '73 cab with original wire, but I don't want o go in there, and even then, I don't want do de-solder or cut any wire to check. Only an "if you know" thing.

    -Gauge
    -Stranded (I think)
    -tinned?

    A source for this wire would be even better.

    Yeah, I'm weird, but probably not alone.

    Thanks!
     
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  2. ampmadscientist

    ampmadscientist Well-Known Member

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    The thinner stock wire makes it sound better. You are not alone.
    The thick wire kills the sustain.
     
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  3. chuckharmonjr

    chuckharmonjr Well-Known Member

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    Excuse me? Wire gauge affects tone? I really hope you are being tongue in cheek with that one. Not suggesting anybody use 350MCM, but 20ga vs. 10ga aint gonna make a whits worth of difference.
     
  4. MikeyV

    MikeyV New Member

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    I just want it to be correct, whatever that may be. My cabs are very original, and I'd like to get the wire looking/routed correct. It' bugs me knowing it's bastardized inside.

    I do believe that wire gauge will change sound...to some degree. I wouldn't venture to say how much.
     
  5. GIBSON67

    GIBSON67 Well-Known Member

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    Here a few pics I have saved...

    $_57CA9EOEMI.jpg 712.jpg try5656567ry56B.jpg
     
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  6. Scumback Speakers

    Scumback Speakers Well-Known Member Sponsor

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    I use 16 gauge copper stranded zip or automotive wire. It's bigger than the stock Marshall wire, which is either 18 or 20 gauge depending on the year of the cab. Frankly, every time I've rewired a cab with the 16 gauge wire it sounds better than the stock wiring, but it's up to you. I find 12-14 gauge to be overkill, hard to solder, and could break off the solder tabs if overheated, so that's why I stick with 16 gauge.

    YMMV, and if you want the original type wire, then you need to start searching. Maybe Bygone Tones can help you with that one, he's in the UK and might know who the original source is.
     
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  7. soundboy57

    soundboy57 Well-Known Member

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    I found some pre twisted red black pre tinned wire somewhere on the net, maybe Ebay a few years back in 18 gauge.

    I used it on a cab and it looked just like the original and sounded great.

    I prefer the 18 gauge, or small original wire myself. I don't know why, but it sounds "better" to me for guitar, than the heavier gauge.

    I rewired a couple cabs over the decades with monster cable, or larger gauge expensive stuff, and it lost the
    magic grind in the mids, don't ask me why, it just did. It had rounder bass, and a bit "cleaner" but not as 'good" as the original stuff, IME. Maybe you have to play it to notice, but I like the tiny original stuff.

    I found it for you
    [​IMG]
    Here is a link to it
    https://www.ebay.com/itm/18-AWG-UL1...RED-Twisted-Pair-25-foot-spools-/332784343591

    Home audio or Pro PA is a different story, though.

    My two cents.
     
    Last edited: Oct 10, 2018
  8. ampmadscientist

    ampmadscientist Well-Known Member

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    Yes Chuck,
    I know this is hard to believe. But prepare to be surprised.
    No dude, this is not a joke it's real.

    It has been shown repeatedly that the wire gauge affects the sustain. The reason why is unknown at this time.

    People who used thick wire lost the good tone. (I'm not sure why this happens)
    But I DO know that it affects the sound.
     
    Last edited: Oct 10, 2018
  9. ampmadscientist

    ampmadscientist Well-Known Member

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    "I use 16 gauge copper stranded zip or automotive wire. It's bigger than the stock Marshall wire..."

    Then, you lost the sound quality.
    This increase in wire gauge DOES noticeably kill the sustain.

    The factory uses 18-20 GA. on purpose.

    If you always thought that thick wire is better - it's not really true, as far as sound quality on a guitar amp.
     
  10. ampmadscientist

    ampmadscientist Well-Known Member

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    "I prefer the 18 gauge, or small original wire myself. I don't know why, but it sounds "better" to me for guitar, than the heavier gauge.
    I rewired a couple cabs over the decades with monster cable, or larger gauge expensive stuff, and it lost the
    magic grind in the mids, don't ask me why, it just did. It had rounder bass, and a bit "cleaner" but not as 'good" as the original stuff, IME. Maybe you have to play it to notice, but I like the tiny original stuff."

    All true. Hard to believe....but the sound proves what you are saying. I can't argue with good results! :applause:

    BUT, WHAT IS THE REASON FOR THIS?

    I'll be damned, I don't know why.
    It has something to do with the "skin effect" of the wire.

    QUOTE:

    "Skin Effect happens in all wire and cable (or in any metal object that conducts a signal, such as a trace on a circuit board or antennas, etc.). When the "signal" is DC, it uses the entire conductor, with the same amount of current flowing in the center of each wire as on the outside of the wire. As the signal changes frequency (i.e. is now a wave changing direction) a very odd effect occurs: the signal begins to move more to the outside of the conductor than the inside. For audio frequencies, which are pretty low frequencies in the spectrum, this effect is so tiny it can barely be measured. Table 1 below shows how much conductor is used at 20 kHz, pretty much the highest audible frequency, and compares that to various wire sizes. (If you want the actual formula for skin effect, drop me a line and I will send it to you.)

    Table 1
    Basis:
    Depth at 20 kHz = 18.4 mils (.0184 in.) Radius x 2 = 36.8 mils (.0368 in.) Diameter


    Amount of conductor used at 20 kHz, based on conductor size
    Conductors Diameter % of conductor used
    24 AWG 0.024 100% at 20 kHz
    22 AWG 0.031 100% at 20 kHz
    12 AWG 0.093 75% at 20 kHz
    10 AWG 0.115 68% at 20 kHz




    You will notice that even for largest wire size, the difference between the inside and outside of a conductor is a few percentage points. Note that this is based on frequency not on the length of the cable, as mentioned in the quote above. You can see this effect very clearly if you look at the impedance of cables at low frequencies. Figure 2 shows the impedance of a 75 ohm video cable from a frequency of 100 MHz (right margin) down to 10 Hz (left margin).You will see that this 75 ohm cable is really only 75 ohm after around 100 kHz and above.Below that it is way higher than 75 ohms.In fact, down at 10 Hz, the impedance of the cable is around 4,000 ohms.

    [​IMG]

    That high-frequency value (75 ohms) is called the "characteristic impedance" of the cable and will stay at 75 ohms (or whatever it was designed to be) out to much higher frequencies. If you compare the low frequency formula to the high-frequency formula, there is one huge difference.R (the resistance of the wire) is a major factor at low frequencies. But in the high frequency formula, there is no R, no resistance.What happened to the resistance?And the answer is "skin effect".As the frequencies got higher and higher, less and less of that conductor is being used, until, around 100 kHz, only the skin is actually carrying the signal.

    This is one reason why we can't build an audio cable to a specific impedance. That number will only apply to one frequency. At a different frequency, above or below, the impedance will be a different value. That's why we don't list the impedance of most audio cables and, if we do, that impedance is measured at some high frequency, like 1 MHz, and that cable might be used for some non-audio application. But perhaps you are thinking, "If the resistance of the wire makes no difference, then why won't a small cable go as far as a big cable?"And the answer is equally simple:the big wire has more skin than the small wire.

    This is why, when we make cables for high frequencies, we spend a lot of time on the surface of the wire.That's the skin. And at high frequencies, that's the only thing working. So we do a lot of things (many of which are "trade secrets") to make sure the surface of that wire is as perfect as we can possibly make it. Our digital video cables, for instance, are sweep tested and measured out to 4.5 GHz. Signals at these highest frequencies use only microinches of the outside of the conductor. If all you were carrying was high frequencies, you could use a copper tube as a conductor with no additional loss compared to a solid conductor.

    [​IMG]This is why our broadband cables are most often copper clad steel (called "CCS" in our catalog). There's only a thin layer of copper on a steel wire.This means such a cable will only work at high frequencies/And that's OK because TV stations start at Channel 2 which is 54 MHz, well into the skin effect range.(Digital channels now start even higher than that.)But someone who uses that cable for low frequencies, such as audio, or to carry DC to power up a satellite dish, will wonder what's wrong with the cable. All the DC power will be going down the steel wire, which is seven times the resistance of copper. What you want for audio or DC power is an all-copper conductor.

    Our digital video cables are all-copper, but that's so you can use them for analog or digital video, analog or digital audio, satellite dishes or pretty much any signal at any frequency from DC to 4.5 GHz. Of course copper-clad steel is a lot stronger than bare copper, something that has saved many a CATV/broadband installer who was less than gentle when installing such a cable.So the next time the salesperson is telling you about the "skin effect" in his speaker cable, well, you know the truth!"
     
    Last edited: Oct 10, 2018
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  11. Scumback Speakers

    Scumback Speakers Well-Known Member Sponsor

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    I'm not going to argue this with you, ampmadscientist. I've had to rewire several dozen old cabs when the original thinner wiring failed, became brittle, etc. I know when my amps do the swell into controlled feedback, that would be hard to do if you had no sustain with 16 gauge wiring. Gotta say I never noticed a lack of sound quality.

    However, because I like to know for a fact if there really is a difference, I'm going to order a spool of that 18 gauge wire from the place on eBay linked above, because I just happen to have an old empty Marshall cab here with diseased wiring and Cliff jack, so while I'm fixing that I'm going to put your theory/belief to the test, and compare it to one of my other old Marshall cabs with identical speakers to see if there's any merit or truth to your statement.

    Sorry, I've learned the hard way that some things have to be tested to believe, and this falls into that category. I'll report back when the wire gets here.

    One last question, exactly what cab (slant / straight, G12M or G12H30 speakers) did you use when you made this determination, including exactly what amp/tubes and guitar was used? Pretty sure I can duplicate almost anything Marshall here for the test.

    Let me know, thanks.
     
    Last edited: Oct 10, 2018
  12. stickyfinger

    stickyfinger Active Member

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    Exactly, because its cheaper than 16.
     
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  13. Scumback Speakers

    Scumback Speakers Well-Known Member Sponsor

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    Well, there is that.
     
  14. MikeyV

    MikeyV New Member

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    HAHA! Cheaper!

    Good discussion, a lot more than I expected. Thanks

    And SOUNDBOY! Thanks for the link, this is perfect. You da man.
     
  15. Scumback Speakers

    Scumback Speakers Well-Known Member Sponsor

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  16. ampmadscientist

    ampmadscientist Well-Known Member

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    Because it causes the amp to sound a certain way...which is much different from 16 or larger.
    Let me emphasis this:
    thick wire causes the sound to change in an undesirable way.
     
  17. stickyfinger

    stickyfinger Active Member

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    While your hypothesis may be a valid one I doubt Marshall would even consider using something completely unnecessary to get the job done
     
  18. soundboy57

    soundboy57 Well-Known Member

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    Just a trick I use to keep from melting the edge of the speaker cover when you are daydreaming about how great it is going to sound....and the magnet pulls your soldering iron in to the cover. I am sure you have seen speakers for sale with this "mod" to
    the covers.

    Get a ceramic cereal bowl that covers the magnet cover you are working on.
    Slip a piece of thin cardbaord or note card under the speaker frame/solder terminals, carefully laid on the back of the cone, to protect the cone from accidental solder drips.

    Put the cabinet face down, and solder on your knees, resting your arm on the cab edge. Start with the top speaker terminals, so you can get a fairly snug wire pair after soldering the bottom speaker on each side.

    A lot of Marshall solder joints are sloppy...only half the wire strands are actually soldered on many cabs. Maybe that's part of the magic tone :)
    Although I would suggest a nicer joint, it just needs the wire hooked on the tab, and small amount of solder applied.

    Don't forget to move the cereal bowl, and the cardboard to the next speaker before soldering.

    Don't rush it, those speakers are valuable.

    It works. I learned what burned plastic smells like, years ago, and it ain't very pretty to look at, either..

    Also, don't forget and leave the solder spool/screw driver in the cab, so it falls and rips a cone when you stand the cab upright.

    I knew a guy that did that with some mint pre Rola speakers. It sounded funny and he found the solder spool
    sitting inside the hole it made in the cone.
    No, it wasn't me. But it coulda been...

    Post some pics.
     
    Last edited: Oct 11, 2018
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  19. Metroman

    Metroman Well-Known Member

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    I think the only time really thick speaker wire thickness is better is when youre running long cables.
    Hard Truckers uses Belden 8473 14 Gauge, and was what convinced me to use this gauge for some JBLs, And Altecs. I had 4 x 1 x 12, and 4 x 1 x 15 made/tuned specifically for E120s, E130s, Altec 418H, and used the Belden
    wire.

    Don't notice any loss of anything. Nor do I think it sounds any better than the 18 gauge wire that's still in the original cabinets they came out of.
     
  20. BygoneTones

    BygoneTones Well-Known Member

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    Dont know the original brand sorry, maybe John will know (London John). Maybe radio spares as a guess, but it is just a guess. I've got some offcuts of original stuff here but not enough to make a full 4x12 harness. There is never any text on it, so difficult to say where it came from.

    I tend to go with the 16 AWG copper too in my cabs, the 14 is too thick to solder. Maybe placebo but I like to go with thicker wire. A lot of the cheaper brands (carlsbro etc) tended to use very thin wire, so in my mind I always associate really thin wire wire as cheap o nasty and cost cutting.

    Fwiw you can twist the wires yourself very easily. You just need to clamp the wires down at one end to a desk or something, and then the other end keep hold of with some pliers, and twist away. If you try to do it completely freehand the twists will not be as uniform and neat.
     
    Last edited: Oct 20, 2018
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