Looking for SUPER SUPER CLEAN mods for Fender Super Reverb

Discussion in 'Amp Tech Center' started by Diverted, Oct 2, 2019.

  1. Diverted

    Diverted Tele-Meister

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    That’s exactly what I’m worried about but weather stripping sounds like a good idea. I’m also going to use a T-nuts and SS screws to lock the baffle into the cleats . Thinking three on bottom and two each side?
    Thanks for that tip!
     
  2. Diverted

    Diverted Tele-Meister

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    Definitely 3/4” BB baffle, into hardwood cleats glued and screwed into cab.
     
  3. kbold

    kbold Tele-Holic

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    For cleaning up output tube swapping is where I would start. Lots of benefits, and without need to solder (i.e. easier).
    Recommendations:
    1) Replacing 7025's with 5751's (30% less output = cleaner), or 12AY7's (as mentioned). For clean, 12AT7's could also be tried. Some brands of 12AX7's will give lots of clean (e.g. Telefunken)
    2) 12AT7's: perhaps try other brands. I have found Telefunken 12AT7's (NOS) to be very clean and with a high ceiling before distortion, compared with other brands.
     
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  4. 39martind18

    39martind18 Tele-Meister

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    Another option: In my 1968 Twin Reverb, I went with Jensen Stealth 100 watt neos. They save about 10-12 lb over the stock speakers at about 5.5lb each. Sound-wise, they have the nice "Fendery" Jensen sound, and are efficient- not as much as the JBL E120, but quite sufficient
     
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  5. kbold

    kbold Tele-Holic

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    I'm thinking your friend may be better off with a solid state amp - cleans all the way to breakup.
    I would be thinking: SS bass amplifier head - there are lots of 500W micro heads available now. Bass amps and amp heads are designed to be clean. Then you only have to build a suitable cabinet to suit.
     
  6. Diverted

    Diverted Tele-Meister

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    Somebody here mentioned an Eminence EM12N and it sounds pretty amazing. And just seven pounds?? Have never heard a neo speaker before but am going to have to check it out.
     
  7. Diverted

    Diverted Tele-Meister

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    Nope, he wants a tube circuit. He’s a big fan of the Twin and blackface amps in general.
     
  8. kbold

    kbold Tele-Holic

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    Celestion G12K-100 should do nicely.
     
  9. avspecialist

    avspecialist TDPRI Member

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    After reading through the reply’s, it seems that basically you want an AB763 amp/preamp, with super reverb voltages. I put in a Heyborer super reverb output transformer in a Bassman 10, rewired the controls the same as a super reverb and used the same tone stack values. If I remember right, in a super reverb the bass, treble then volume are wired in. it’s opposite of other amplifiers. Then I would use a Weber California, which is very efficient, at least 3 dB more than a Jensen and some of the JBL’s. and that’s like having double the power. It’s also bright and clean. get it with the paper dome. Use low breakup output tubes, really check out the Preferred series, tubes from The Tube Store. I also make my cabinets a little deeper than Fender. I go to Home Depot and pick a nice clean 1X12, which is actually 3/4 by 11 1/2, cut it to size. Now to assemble the cabinet i use but joints, glued, and then I drill into the sides and put in 2 1/2 trim screws every 2 inches to hold it together, having corner clamps makes a big difference in squareness of the cabinet. It does a great job of emulating a finger joined cabinet for strength. I have found 1/2 inch MDF the right tone wood for the baffle and i bolt that in using threaded inserts through glued and screwed cleats. This is a very solid and nicely resonant cabinet. Make the back opening about 5 inches. I’m sure this design is a winner, I have made this myself and people always comment how clear the sound is.
     
  10. BobbyZ

    BobbyZ Doctor of Teleocity

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    It is to a point but only goes so far. For example my DR with its Maverick full up, (99db or so) next to my TR with Radio Shack Utahs gets left behind in a volume war. Those old RS speakers aren't very efficient at all, why I like um in the TR. But at the end the day the TR gets louder, a lot louder.
    But yeah efficiency matters ! Just won't turn a small amp into a big one. It can turn a small amp into one that's too loud though. That's why I like the Maverick FDM concept.
    These days volumes are low, Princetons and Deluxes are actually worth money now and SRs and Twins aren't.

    Still like to know where this dude plays. Lol
     
  11. Diverted

    Diverted Tele-Meister

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    Thank you so much for the tips. Yes, that's exactly what I'm looking for. I have never used MDF before and will give it a go (may build two cabinets to different specs for him). Anyway, I usually dovetail the corners and blue it up, but I have not screwed through before. I will this time though. And I'll be using corner braces as well. As for tubes, I have a pretty wide selection of US/British/German NOS and pull vintage preamp and output tubes... We'll swap stuff around until we find something he likes.
    I have a question about the power transformer. I was thinking about using a Heyboer transformer built for bassman specs, which is 352-0-352@250ma. Chose this one after seeing several different "Super Reverb" transformers, all with different current ratings, and figured for cleaner I should just go with the highest I found. Mojotone lists this Bassman transformer as a sub for Bassman and Super. Seems like it's definitley got plenty of current capacity. Which did you use? I'll be using a Heyboer output transformer and Heyboer choke.
    Thanks!
     
  12. schmee

    schmee Poster Extraordinaire

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    Yes that should be plenty I would think. I think a Super Rev is 325-0-325 and 200 ma...?
     
  13. Diverted

    Diverted Tele-Meister

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    It's been confusing, trying to find correct ratings. Original Fender schematic for transformer 125PSD is 360-0-360, but I couldn't find any note on current capacity. It uses a GZ34 rectifier so I would think 350-0-350 would be just about perfect for me as I'll be going solid state. 250ma is big so the voltages may be a bit higher if the original was 200.
    Think I will go with the Bassman@250ma as any extra unused current will only help clean headroom. Thanks!
     
  14. JD0x0

    JD0x0 Poster Extraordinaire

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    LNFB on the mixer stage.
    Post phase inverter cathode followers (can repurpose tremolo tube for this, if you don't mind giving up the trem) You can use the holes for 'Dwell' and 'tone' for the reverb.
    Reduce dropping resistors for higher preamp B+
     
  15. JD0x0

    JD0x0 Poster Extraordinaire

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    Easy to swap, but IMO, not ideal.. Here's why...

    The 12Ax7 tubes in the preamp should already be 'center biased' on the load line, which gives maximum headroom. By haphazardly swapping in lower gain tubes, you're changing the load line, which reduces headroom. Now, the tubes DO have less 'gain' which means they hit the following stages with less signal. Less signal, will tend to reduce distortion, BUT, you could've done the same exact thing by turning the volume down, or even changing the volume/gain control to a lower value (with a larger coupler to keep the HPF the same) or removing cathode bypass cap(s) to reduce gain and distortion on those stages.

    Many people will perceive the lower gain tubes as 'higher headroom' due to the reduced gain, but it's more of a placebo, IMO, because you didn't actually gain any headroom. You simply reduced gain hitting the following stages, so you feel like you can turn the volume control up more, for the same amount of distortion, and this makes you 'feel' like the amp gained headroom because now "It breaks up on 6 instead of 4". That's not actually increased headroom, though..

    Now, that's not to say you can't get good sounding results, or desirable properties with the lower gain tubes, but if your true goal is 'headroom' you're actually going in the opposite direction, in many cases unless you're changing plate/cathode resistors with the tube changes, to keep the load line on those tubes centered.
     
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  16. telemnemonics

    telemnemonics Doctor of Teleocity Ad Free Member

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    All this is interesting on paper (or in digital reality) but I wonder if your customer has clearly defined loud and clearly defined clean?

    First off I'd question you mentioning that a Super is a "very very clean amp".
    Most of us who love a nice SR go there for the dirt, as it tends to be one of the better BF amps for dirt. I've had four over the years, a favorite.
    Making it smaller, and cleaner at the same volume?
    Sure that can be done but it wasn't a particularly clean amp to begin with.
    I have similar wishes these days and consider clean volume to come primarily from four heavy parts.
    PT, OT, speaker and power tubes.
    Make them all smaller with the goal of cleaner?

    The bigger PT in the UL Fenders runs the power tubes at higher voltage resulting in higher clean volume.
    My sense is that the smaller PT in a Twin will get more clean volume with 4x6L6 from a lighter amp, compared to the extra PT weight to produce the higher voltage.

    I would not use KT66 for the purpose of cleaner at the same volume.
    My choice for cleanest power from a pair of octal power tubes would be old Philips Sylvania 6L6 or 6ca7.
    I have a light weight amp (Carr Hammerhead) that runs a pair of el34/ 6ca7/ 6550 or KT88.
    Only a 28w cathode biased amp but cleaner with the loafing high power tubes.
    Designed for dirt but clean is similar to a vintage Marshall turned down, which in many cases had louder/ cleaner sound than a same number of power tubes BF/SF Fender amp.

    Most of my info comes from lots and lots of amps, but I did pay a good tech to mod a SFSR with more filtering, added a plug in SS rectifier, and used higher power handling cleaner speakers.
    Sounded stiff and lost all the feel of a BF/SFSR.
    A BF Bassman head does what I wanted and better than the modded 2ohm combo.

    Going for a small 1x12 loud clean combo I don't see what SR features are of any use?
    Maybe the PT?

    I have an old SF Princeton modded into a 6L6 amp with both transformers replaced.
    Gets better loud cleans than the Carr, weighs a little more too.

    I'm also liking the loud cleans from a 4xel84 head with an AC30 OT.
    I have several different 4xel84 amps and most are less about cleans than this one, plus weigh more.
    The Dr Z Stang Ray is loud and clean but almost as heavy as a Twin chassis, and the feel isn't what I like.
    Selecting a bunch of components and a circuit from various sources isn't guaranteed to be a recipe the customer will love every day for years...

    Given that many of us feel a SR has a nice early breakup in a group setting, where your customer feels a SR has late breakup, maybe a 2x6v6 amp built for cleans would satisfy his need for loud/ clean/ light weight?
     
  17. David Barnett

    David Barnett Doctor of Teleocity

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    Non-reverb BF Princeton-Amp will just barely "crunch" if you dime it. The same cannot be said for the non-reverb BF Deluxe-Amp, it will distort (pleasantly).
     
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  18. avspecialist

    avspecialist TDPRI Member

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    I believe this is he output transformer i used in my Bassman ten to make it a super reverb SKU # MOJO774, It was substantially better than the bassman ten output transformer. It had deeper bass response and higher treble response and it much more open and out off the box sounding for a given volume.From what I read, and what you are saying, the super reverb design and the Weber California will do the job. it’s very open and dynamic. Also noting the other replies, by 67 super reverb is very clean and loud till 4 with the bass at 6, mids at 9 and the treble around 5. I like it a lot with my 1969 Gibson SG Custom. when you get over 4 it starts to compress and get real crunchy. I can get very similar Black Sabbath and Led zeppelin sounds out of it. At 4 and under it’s great for Beatles and Stones and a lot of others. It’s a great amp. Swap in the right tubes as designated by the circuit and play around with the different brands and you will have a winner. I wouldn’t use a 12ax7 as the PI, it sounds very mismatched. I have been design Audio systems for over 50 years and have really know system combinations. Enjoy and make the customer happy
     
  19. muchxs

    muchxs Doctor of Teleocity

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    I use glue, no screws.

    It sucks when a screw backs out under the covering.
     
  20. avspecialist

    avspecialist TDPRI Member

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    not if you fill the holes with wood filler, I never had a problem, you hav e to use 2 1/2 inch trim screws. Glue will eventually fail over time.
     
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