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Fun modding the '66 Super

Discussion in 'Amp Tech Center' started by Luthier Vandros, Mar 8, 2021.

  1. Luthier Vandros

    Luthier Vandros Tele-Afflicted

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    For grins, I've decided to test a few reversible mods. Here they are along with my impressions:

    1. NFB defeat switch - The single most useful mod I've ever implemented in a BF amp. Richer tone with immensely more touch sensitivity and smoothness into breakup. Lowers headroom just the right amount and adds sparkle, so yo can turn off the bright switch and have your amp play nicer with a wider variety of OD pedals (if that's your bag). It only adds a little bit of hiss. It also plays well with the next two mods.

    2. Split V1/2 shared cathode - Given that my amp was already nearly noise free, with the exception of 2 NOS 12AT7s, I actually realized a little decrease in background hum. I used an existing anchor point courtesy one of the doghouse bolts near V2 and added a single lug terminal strip. I ran the jumper from V to V2 over to this lug and added a 1.5K/25uf to ground.

    3. Decrease V2 cathode resistors to 820R/1K - Subbing in the 820R made an obvious difference to the feel and tone of this incredible Super. I clipped in the leads from my decade box and went to town before landing on that value. This gave me the perception of a little compression on the front end of the note and the amp sounds and feels juicier from 2 on up on the volume. Moving back to the pair of 1.5Ks brought back in a sharper attack with less of the grease. It’s all blackface fender either way.

    This is a really cool mod that really embellishes the amp running without feedback. I ran V2's 820R prior to splitting it and felt this was a great standalone mod to implement along with the NFB defeat switch. The newly implemented independant cathode RC combo to ground was negotiable, but then again, I haven't spent time exploring the possibilities. As it stood, it was total Lenny tone with my strat with the super on "3" - huge, tight bottom end with piano resonance coupled with a juicy and lively top end with grease beneath the fingers.

    4. Hum balance pot - This removed the remaining 10% of background buzz from the amp. A very easy mod and one that will be with this super until the end.

    5. Unbypassed reverb driver - I felt like I needed a new pan, because the tone of the reverb signal was a little metallic and flat. Think of a metal storm drain. After refreshing the resistors in the reverb circuit and realizing some nice gains in lushness and presence, I went after that Silverface Super whose reverb tone haunted my dreams since I serviced it. I should have taken more measurements!

    I removed the 2.2k/25uf RC combo and subbed in a 1.5K for a little gain makeup. This did the trick; Useable reverb from 2-8 on the dial and it's lush and spacious without being obnoxious and over-drippy. it's incredibly lush and atmospheric. Don't do this is you want surf or clam fest tone.

    6. .047uf vib channel coupling cap - For this particular Super, this really gave this channel the fullness that the normal channel has. No negatives even with the amp cranked. As an aside, I tried doubling the PI input cap, but found that created a very boomy low end.

    All of these amp are old hat to most of you and have stood the test of time for a reason. I just wanted to weigh in with my thoughts, as these have made an already enjoyable amp (even at bedroom volumes) even more fun to play.
     
    Last edited: Mar 8, 2021
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  2. Wally

    Wally Telefied Ad Free Member

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    Luther, if you ever get curious, try a potentiometer in series with the 820ohm NFB loop resistor. A 5K works. There are subtle stops along the way between sock NFB and none at all that you might find useful, and there are times when one might want to have a stock SR sound. Also, you might apply the effects to that Normal channel. I also revoice that channel to reduce the midrange dip and to emphasize the midrange. My thought is why have two channels that sound essentially just alike??
     
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  3. Luthier Vandros

    Luthier Vandros Tele-Afflicted

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    Wally, I always love where your mind is at, brother. I'm looking at some normal channel experiments that may make their ways over to the trem channel.
     
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  4. Wally

    Wally Telefied Ad Free Member

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    Luther, there is even a way to have a midboost switch by changing out that slide switch. I generally leave the Vib channel alone except for restoring the stock gain by using a 1.5K ohm cathode resistor after removing that 820ohm that is used for the tied cathodes.
     
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  5. Luthier Vandros

    Luthier Vandros Tele-Afflicted

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    Right on. I added a super champ boost switch to one of my former AB763's. Was super tasty and was always on.
     
  6. Luthier Vandros

    Luthier Vandros Tele-Afflicted

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    Wally,

    I was able to crank the amp up to 4 today lol. Without NFB, there was nice crunch and loose low end. With it, the amp stayed tight and clean. I’m thinking about implementing that pot now. Would be nice to have those shades of tone at different volume levels.
     
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  7. Luthier Vandros

    Luthier Vandros Tele-Afflicted

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    Wally, the 10K pot proved very useful. Such a lovely amp at any volume!
     
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