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Thread: 68' Twin Reverb AB763 Help

  1. #41
    Forum Member Michael Smith's Avatar
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    Re: 68' Twin Reverb AB763 Help

    Quote Originally Posted by Outlaw17 View Post
    I have another question, What's the correct speaker placement for a 1968 twin? Side by side or one higher than the other??
    From the photos I see on Reverb of 1968 or 1969 Drip Edge twins, the speakers appear to be exactly side by side.

    In fact there is one for sale in Austin with JBL speakers. The cabinet is in pretty rough shape though.
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    Re: 68' Twin Reverb AB763 Help

    Quote Originally Posted by Michael Smith View Post
    From the photos I see on Reverb of 1968 or 1969 Drip Edge twins, the speakers appear to be exactly side by side.

    In fact there is one for sale in Austin with JBL speakers. The cabinet is in pretty rough shape though.

    Thanks I wasn't quite sure, The tolex on my cabinet is in way worse shape than that one! LOL The amp looks like its been to mexican hell and back! But is worthy of restoring. Especially since it's on of my bucket list amps to owe!

  3. #43
    Forum Member Michael Smith's Avatar
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    Re: 68' Twin Reverb AB763 Help

    Do you plan to put new tolex on the cabinet at some point? If you remove the old tolex, be sure to check the wood joints and inject some wood glue if needed. Uncle Doug has a video or two about applying tolex.

    Here is a photo of my 1969 Super Reverb halfway thru removing smoke stains and other grime from the grill cloth.
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    Re: 68' Twin Reverb AB763 Help

    Quote Originally Posted by Michael Smith View Post
    Do you plan to put new tolex on the cabinet at some point? If you remove the old tolex, be sure to check the wood joints and inject some wood glue if needed. Uncle Doug has a video or two about applying tolex.

    Here is a photo of my 1969 Super Reverb halfway thru removing smoke stains and other grime from the grill cloth.

    Nice! I do plan to eventually replace the tolex cause its in pretty bad shape. Although! It does have the relic look. HAHA

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    Re: 68' Twin Reverb AB763 Help

    They cut the tolex from the inner parts of the chassis to install the seat vinyl...






  6. #46
    Forum Member Michael Smith's Avatar
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    Re: 68' Twin Reverb AB763 Help

    You've got a good project amp there. If you plan to buy and install the tilt back legs and the "stops" after you put new tolex on, make a template of where the existing holes are, because the screws for the stops don't penetrate through the sides of the cabinet. A friend had to take precise measurements off of my Super Reverb, because he had covered the old holes with tolex and wanted to find them without poking a bunch of holes in the tolex.

    For my mid 70's Super Twin Reverb, I built a separate cabinet for the chassis, because the thing weighed about 100 pounds. Note the monster magnets on the Utah speakers. It could always be put back in the original cabinet by removing a strip of wood I inserted, but my amp isn't very valuable (or desirable).

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  7. #47
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    Re: 68' Twin Reverb AB763 Help

    An easy method for marking the location for the tilt-back stops is to insert a ¼" round-head screw into the hole for the stop prior to affixing the Tolex. Once the adhesive has cured, use an X-acto knife to score all the way around the head of the protruding screw then peel off the small disc of Tolex. Remove the screw and the original hole is marked to permit reinstalling the stop.
    "When injustice becomes law then rebellion becomes duty."

  8. #48
    Forum Member Michael Smith's Avatar
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    Re: 68' Twin Reverb AB763 Help

    Quote Originally Posted by phantomman View Post
    An easy method for marking the location for the tilt-back stops is to insert a ¼" round-head screw into the hole for the stop prior to affixing the Tolex. Once the adhesive has cured, use an X-acto knife to score all the way around the head of the protruding screw then peel off the small disc of Tolex. Remove the screw and the original hole is marked to permit reinstalling the stop.
    Great tip Phantomman!. My buddy could have used that advice a few months ago, lol.
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  9. #49
    Forum Member phantomman's Avatar
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    Re: 68' Twin Reverb AB763 Help

    I've been at this for a while. I know a few tricks.

    "When injustice becomes law then rebellion becomes duty."

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    Re: 68' Twin Reverb AB763 Help

    [QUOTE=Michael Smith;655419]You've got a good project amp there. If you plan to buy and install the tilt back legs and the "stops" after you put new tolex on, make a template of where the existing holes are, because the screws for the stops don't penetrate through the sides of the cabinet. A friend had to take precise measurements off of my Super Reverb, because he had covered the old holes with tolex and wanted to find them without poking a bunch of holes in the tolex.

    For my mid 70's Super Twin Reverb, I built a separate cabinet for the chassis, because the thing weighed about 100 pounds. Note the monster magnets on the Utah speakers. It could always be put back in the original cabinet by removing a strip of wood I inserted, but my amp isn't very valuable (or desirable).

    [/QGeez Louize that's some huge magnets!! I love the look of the twin reverb but not the weight... Thought about getting a head cabinet for it as ill never sell it. Bet that thing would scream threw a 4x12 cab!

  11. #51
    Forum Member Michael Smith's Avatar
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    Re: 68' Twin Reverb AB763 Help

    Before it was modified, it had six 6L6 power tubes and power output was 180Watts RMS, 395 Watts peak. Ted Nugent used six of them with the big Showman extension cabinets. It sounds really nice at low to mid volume; the so-called distortion circuit is terrible. I'm toying with the idea of gutting the chassis and making it into an AB763 circuit. I would need an eyelet board and a couple of different preamp tube sockets, as it uses 2 very odd tubes in it's current configuration.
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    Re: 68' Twin Reverb AB763 Help

    Quote Originally Posted by Michael Smith View Post
    Before it was modified, it had six 6L6 power tubes and power output was 180Watts RMS, 395 Watts peak. Ted Nugent used six of them with the big Showman extension cabinets. It sounds really nice at low to mid volume; the so-called distortion circuit is terrible. I'm toying with the idea of gutting the chassis and making it into an AB763 circuit. I would need an eyelet board and a couple of different preamp tube sockets, as it uses 2 very odd tubes in it's current configuration.

    I do love the AB763 circuit, Its the better Blackface circuit if you ask me! I was in shock when dude offered to trade me this amp for a Jackson RR JS32! the cheapest guitar they make! lol

  13. #53
    Forum Member Michael Smith's Avatar
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    Re: 68' Twin Reverb AB763 Help

    Maybe he doesn't check sites like Reverb or E-bay to see what they are selling for. Even if you don't work on the cosmetic things, if you get the chassis in order you will have a great amp. You may be able to get some aluminum flashing at Home Depot to replace the missing drip edge. You only need to worry about the edge that shows being cut straight. You may have to buff it up with some sandpaper or steel wool or perhaps a chemical to get it aged like the pieces you already have. I checked on Ebay and couldn't find the vendor that Phantomman said was selling drip edge extrusions, but I didn't search all that long.

    The circuit revision after AB763 was AC568. That used a hybrid fixed/cathode bias scheme. Fender didn't stick with that for long. Then by the mid to late 70's they added master volume controls and came out with things like the Quad Reverb (4 x 12) Super Six Reverb (6 x 10), and monstrosities like my Super Twin Reverb.
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    Re: 68' Twin Reverb AB763 Help

    Quote Originally Posted by phantomman View Post
    The original baffle board was ½" MDF with a ¼" pine surround and logo shelf, similar in construction to this......



    The correct speaker for an authentic 1968 restoration is an Oxford 12T6 or JBL's D120F. Twin Reverb's with factory-installed Lansing's featured a JBL logo at the lower right corner of the baffle board which required a small rectangular logo shelf similar to this......
    Beautiful work there on that cabinet, if OP don't mind me saying.

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    Re: 68' Twin Reverb AB763 Help

    Quote Originally Posted by Michael Smith View Post
    Maybe he doesn't check sites like Reverb or E-bay to see what they are selling for. Even if you don't work on the cosmetic things, if you get the chassis in order you will have a great amp. You may be able to get some aluminum flashing at Home Depot to replace the missing drip edge. You only need to worry about the edge that shows being cut straight. You may have to buff it up with some sandpaper or steel wool or perhaps a chemical to get it aged like the pieces you already have. I checked on Ebay and couldn't find the vendor that Phantomman said was selling drip edge extrusions, but I didn't search all that long.

    The circuit revision after AB763 was AC568. That used a hybrid fixed/cathode bias scheme. Fender didn't stick with that for long. Then by the mid to late 70's they added master volume controls and came out with things like the Quad Reverb (4 x 12) Super Six Reverb (6 x 10), and monstrosities like my Super Twin Reverb.
    Most definitely! Honestly it sounds great as is but I want it to sound like 1968. Kinda like the relic look though.. I'll rebuild the baffle and get aged grill cloth for sure. Mostly concerned with restoring the circuit to as original as possible.

  16. #56
    Forum Member Michael Smith's Avatar
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    Re: 68' Twin Reverb AB763 Help

    Compare it to John & George's amps in the Get Back film, as that is the amp they were using.
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  17. #57
    Forum Member Michael Smith's Avatar
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    Re: 68' Twin Reverb AB763 Help

    Quote Originally Posted by Outlaw17 View Post
    Most definitely! Honestly it sounds great as is but I want it to sound like 1968. Kinda like the relic look though.. I'll rebuild the baffle and get aged grill cloth for sure. Mostly concerned with restoring the circuit to as original as possible.
    Outlaw 17. I was trying to send you a private message with a mp3 file attached showing my super twin reverb in action, but couldn't figure out how to do it. If you know, send me a PM.
    "When You're Riding Down the Highway at Night, And You're Feeling that Wild Turkey's Bite" ZZ Top

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    Re: 68' Twin Reverb AB763 Help

    Quote Originally Posted by Michael Smith View Post
    Outlaw 17. I was trying to send you a private message with a mp3 file attached showing my super twin reverb in action, but couldn't figure out how to do it. If you know, send me a PM.
    Not sure how to do that either. 🤔

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    Re: 68' Twin Reverb AB763 Help

    I can't seem to find any other writing on the power tubes other than Sovtek. Could they be old stock tubes? They appear to be the Sovtek WXT+ backplate tubes.

  20. #60
    Forum Member phantomman's Avatar
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    Re: 68' Twin Reverb AB763 Help

    Quote Originally Posted by Outlaw17 View Post
    Not sure how to do that either. ��
    Click on Michael's log-in on any of his posts. A dialog box will appear with several options. Choose "privage message" and a new pre-addressed window will open. Then merely type your message and hit "send".
    "When injustice becomes law then rebellion becomes duty."

  21. #61
    Forum Member Michael Smith's Avatar
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    Re: 68' Twin Reverb AB763 Help

    Quote Originally Posted by Outlaw17 View Post
    anyone know where i can find the drip rail? I'm missing one piece and all the corners..
    I just had a fresh thought on this after watching Psionic Audio repairing a '68 Custom Deluxe Reverb reissue amp. They come with the drip edge like the actual 1968's. Perhaps you can contact Fender to see if they have the drip edge extrusions and corners for sale. Or maybe they could tell you where they get the modern ones made.
    "When You're Riding Down the Highway at Night, And You're Feeling that Wild Turkey's Bite" ZZ Top

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    Re: 68' Twin Reverb AB763 Help

    Quote Originally Posted by Michael Smith View Post
    I think the Tube Works 12 G is an Eminence 100 Watt speaker. There should be a label with some codes glued to the sides of the magnets. Looks like the speaker baffle has been replaced, as I think the originals were painted black.

    Now that I can see a glimpse of one of the balancing resistors under the reservoir cap, it is a 220K ohm. Looks like the original carbon comp resistor. I normally change those out for Metal Oxide's, but if they measure OK that could probably wait until the next cap job.

    So I finally got the caps to replace the odd ones, You wouldn't happen to know a way to safely discharge the caps so I can change them out?? I don't have a resistor with a high enough value to discharge them... ALSO retube the amp with NOS GE 12ax7 and 12AT7s JJ 6L6GC's and OMG!! Sweet!!!

  23. #63
    Forum Member Michael Smith's Avatar
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    Re: 68' Twin Reverb AB763 Help

    Quote Originally Posted by Outlaw17 View Post
    So I finally got the caps to replace the odd ones, You wouldn't happen to know a way to safely discharge the caps so I can change them out?? I don't have a resistor with a high enough value to discharge them... ALSO retube the amp with NOS GE 12ax7 and 12AT7s JJ 6L6GC's and OMG!! Sweet!!!
    I sent you a private message about discharging the caps. For some reason I am not getting notified when a new private message comes in. I just happened to go to my inbox and saw your message from earlier today.
    "When You're Riding Down the Highway at Night, And You're Feeling that Wild Turkey's Bite" ZZ Top

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    Re: 68' Twin Reverb AB763 Help

    Quote Originally Posted by Michael Smith View Post
    I sent you a private message about discharging the caps. For some reason I am not getting notified when a new private message comes in. I just happened to go to my inbox and saw your message from earlier today.

    TADA!! It wouldn't let me send pics in private messages...[IMG][/IMG][IMG][/IMG]

  25. #65
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    Re: 68' Twin Reverb AB763 Help

    Quote Originally Posted by Outlaw17 View Post
    I have another question, What's the correct speaker placement for a 1968 twin? Side by side or one higher than the other??
    I saw this answered already, but wanted to add that a lot of times the speaker placement has to do with the size of the cabinet and if there's room for clearance from the transformers.

    For example, in my 2x10 Hot Rod Tweed Pro, you have to stagger the two speakers because they won't fit in the existing cab next to one another:



    However, in my BFPR repro, I have a 12" speaker in there and it needs to be off to the side to clear the transformers:







    Just some extra info for ya'! (oh, and I got that speaker from Phantomman a long time ago. It works well in this amp although not the traditional choice )
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