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Thread: Twin Reverb Master Volume 135w speaker impedance?

  1. #1
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    Twin Reverb Master Volume 135w speaker impedance?

    Hello,

    I'm trying to find some replacement speakers for a Twin Reverb 135w version. Normally a simple task, but the cab came to me without the original speakers and the stamp on the back plate is confusing me.

    It says "minimum load" and then "8 ohm" under both the main and EXT. speaker jacks.

    First off, I thought all twins were 4 ohm, but does that mean I need two 16 ohm speakers wired in parallel or does that mean if I hook up the EXT jack then I need 8 ohms total or what??? I'm not even sure what to ask????

    It seems simple... I have been testing and repairing the amp with an 8 ohm test speaker, but I now need to stuff the cab with speakers, so need to know which ones to get. BTW, any speakers recommendations would be appreciated as well.

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    Re: Twin Reverb Master Volume 135w speaker impedance?

    My UL Twin has 2-8 ohm JBL's in it, (orange frame).

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    Re: Twin Reverb Master Volume 135w speaker impedance?

    Totally agree with Bill Moore . The schematic calls for 2-8ohm speakers. More specifically, it calls for 2-8 ohm speakers capable of handling 135 watts together.

    I understand why you might be confused. Do a search for "fender 135 watts schematics".

    You'll only find one schematic for a "twin reverb", a "quad reverb" a "super six reverb", a "dual showman reverb". They all call for a 4-ohm load You'll also find the vibrosonic reverb on that schematic. And if you look carefully on that schematic the output jacks for the vibrosonic reverb are different and stipulate an 8-ohm load.

    My WAG would be that you have a twin reverb, but when Fender built it, they were out of of the correct back panel plates. The vibrosonic reverb is the only model that calls for 8 ohm minimum speaker. There is no difference, as long as the Fender part number of your output transformer is 013691.

    I really hope that this doesn't leave you more confused than when you first came here, but basically the amp is looking for a 4-ohm load.

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    Re: Twin Reverb Master Volume 135w speaker impedance?

    I think vinyl is on to something. Check the numbers on the OT, my Twin says 4 ohm under the jacks, but a silverface VR on reverb has 8 ohm under the jacks.

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    Re: Twin Reverb Master Volume 135w speaker impedance?

    The thing to do is get a 4 x 12 cab w/ name brand speakers , wire it parallel with a new metal switchcraft jack , and get a fresh speaker cable and you will be good to go. Those amp have too much power to run any kind of speakers w/open back that will ever sound good. Ive been playing , repairing, moding , troubleshooting, these pull boost Mv Sf Fenders , from the late 70's they are my amp of choice.

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    Re: Twin Reverb Master Volume 135w speaker impedance?

    Quote Originally Posted by vinyl View Post
    Totally agree with Bill Moore... as long as the Fender part number of your output transformer is 013691...
    Yes, just checked. The output part number 013691. So, WTH, could it be on a 8 ohm tap or something? So two 8 ohms speakers wired in parallel?

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    Re: Twin Reverb Master Volume 135w speaker impedance?

    I just looked at the UL chassis I have waiting on a refurb. OT 013691 has multitap output, there is a green and a yellow/green. The AUX jack is a switching jack with green wire connected to the main, and switching to yellow/green when a jack is inserted. The schematic shows a different switching arrangement for the Vibrosinic using 2-8 ohm loads.

    https://www.thetubestore.com/lib/the...-Schematic.pdf

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