silverface twin

Discussion in 'Glowing Bottle Tube Amp Forum' started by duffer426, May 12, 2019.

  1. duffer426

    duffer426 TDPRI Member

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    traded for a silverface twin( early 1973 model has tail on fender logo.) On further exam I noticed speakers are Oxford 12L6 should they be 12T6? also where can I find the circuit number since there is 3 differant circuits with this amp.
     
  2. Wally

    Wally Telefied Ad Free Member

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    If your amp is a ‘73, it has a master volume, yes? If so, this schematic will be as close as you will get to that amp.
    https://schematicheaven.net/fenderamps/twin_reverb_sf_100_schem.pdf
    I am never concerned about a circuit number in these ‘70’s amps. And....the use of old tube charts in maps with circuits that superseded the old circuit n7mbers on the tube chart make me not pay a lot of attention to the earlier BF and Sf amps.
    And, yes, ime the speakers should be 12T6 if they are OEM Oxfords in a TR.
     
  3. corliss1

    corliss1 Friend of Leo's Platinum Supporter

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    Get it checked out by a tech too :D
     
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  4. Milspec

    Milspec Friend of Leo's

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    If it has the tail still, it was likely assembled in '72 as that was the final year for them. I think the AB763 circuit ended in '68 or '69 so you probably have an AC568 circuit which is easy to Blackface if desired. Does it have a push-pull pot on it like in the late '73 models? I ask because one could always replace the logo to an earlier design, but it takes a lot more to eliminate the push-pull feature.

    You are correct that it should have Oxford 12T6 speakers stock, but I have seen a lot of Utah 12" speakers in there as well.
     
  5. Ten Over

    Ten Over Tele-Meister

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    Here is a schematic for an early '73 Twin Reverb. Would love to see some gut shots of your amp. Twin Reverb 100W 1973.gif
     
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  6. Wally

    Wally Telefied Ad Free Member

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    It will not have a 1968 circuit if it is from anytime after the summer of 1969.....regardless of what the tube chart says, ime. After the AC568 circuit, there was an AA769...July, 1969....circuit, then an AA270 circuit drawn in Feb, 1970. That was followed by the first 100 watt circuit and then the master volume circuit. ​
     
  7. duffer426

    duffer426 TDPRI Member

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    It has the master volume,but it is not push pull.Also on the back panel it says 100 watt rms
     
  8. duffer426

    duffer426 TDPRI Member

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    thanks for schematic Ten wil get pics of chassis guts soon
     
  9. duffer426

    duffer426 TDPRI Member

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    should I change the speakers are they able to handle the output of the amp
     
  10. Wally

    Wally Telefied Ad Free Member

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    The schematic I gave in my post two covers your amp.
    Speakers...imho, a set of 12T6’s from anytime from 1966 on would give you a Twin Reverb that can be turned up a bit before blowing out windows since they are low efficiency. If you don’t run that amp at higher volume settings...master volume settings....then the L6’s should stand up. I remove the MV from these amps since ime they are of little use anyway. I use that hole for a pot to adjust the negative feedback. Ommv.
     
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  11. Milspec

    Milspec Friend of Leo's

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    The letter code on Oxford speakers tell you the power handling. Further down the alphabet...higher the power rating. So, an "L" would likely be about 35 watts which is pretty low for a 100 watt Twin. Since you are not likely going to crank it above 2 in the house, they would survive, but it really would benefit from a speaker upgrade of 75w speakers at least. I would take a look at the WGS website and you will find what you want.
     
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  12. jimbo735

    jimbo735 Tele-Afflicted

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    Having a bias adjustment pot added will give you the advantage.:D
     
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  13. thegeezer

    thegeezer Tele-Afflicted

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    L are 30 watts actually.

    M are 35.

    T stood for Twin. Guesses vary from 45-60.

    But...that was optimistic. I love Oxfords, by the way, and the 12t6 Oxfords in my ‘74 TR have held up through decades of being used and abused by me and still sound great.
     
  14. robrob

    robrob Poster Extraordinaire Ad Free Member

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  15. Milspec

    Milspec Friend of Leo's

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    30 watts? Even worse then, I would upgrade
     
  16. BobbyZ

    BobbyZ Doctor of Teleocity

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    I don't get too worried about speaker's wattage ratings in a TR, because volume will limit the wattage they see.
    That said if you play loud like, cops get involved and you get kicked out of bands loud, then it can be a concern.
    Most of us can't crank a Deluxe Reverb these days though. :)
     
  17. Milspec

    Milspec Friend of Leo's

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    Very true, but we all have that buddy who after a few beers will crank it up or even the owner accidently turning things up way too high (I am guilty as charged to the latter)
     
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  18. Wally

    Wally Telefied Ad Free Member

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    I don’t worry about it. I simply avoid putting in speakers that can handle whatever I decide to put the amp through. If you install some very low efficiency speakers, like Oxford 12T6’s from any year after 1965, you can turn a TR up enough to get it cooking without dealing out pain. Mod the thing to have some difference between the channels and to make the amp livelier...richer. Great low volume amp. Great medium volume amp. Great high volume amp. Great amp......worth the weight.
     
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  19. duffer426

    duffer426 TDPRI Member

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    here are some pics IMG_0771.JPG IMG_0772.JPG IMG_0773.JPG IMG_0771.JPG IMG_0772.JPG IMG_0773.JPG IMG_0774.JPG IMG_0775.JPG IMG_0776.JPG IMG_0777.JPG IMG_0778.JPG IMG_0779.JPG IMG_0780.JPG
     
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