5F11 recap & tweaking

Discussion in 'Shock Brother's DIY Amps' started by jsnwhite619, Jan 10, 2020.

  1. jsnwhite619

    jsnwhite619 Friend of Leo's

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    So, around 6 months I sold the cabinet for my 5F11 Vibrolux. I finally got around to starting a new one for it this week, and when I got the chassis out I decided to do some work on it. It was the last amp I built with the Mojo small parts kits before I just started sourcing all my own stuff. Those big neon blue filter caps had to go. So, the 16uf Mojo caps swapped with 22uf F&T's. And the 22k dropping resistor was a 1/2 watt carbon comp that I changed out to 2 watt metal film today as well. I also changed the PT secondaries again, back to the 315v instead of the 275v taps.

    Well, I've got to say I like the changes! The tremolo definitely benefited from the filter cap change. It is stronger & deeper than before, and it just seems to last forever, sustain-wise.

    Measurements, all JJ's:
    • 383v plate to cathode
    • 20.7mA
    • 56%
    • B+ goes 387v, 384v, 296v
    I played it a while tonight through my Pro Jr cabinet & Ragin Cajun. The cab is 16x18 pine cabinet I built a few years back. I liked it! As big as a Ragin Cajun can sound, it definitely sounds all 10" speaker with this, but in a good way. It's snappy, sounds more like a Princeton Reverb to me. So, here it is mic'd, amp volume on 4, tone on 7.



    I also ran it through my Cannabis Rex stuck into a 1x12 test cabinet I built a while back. It only around 9" deep and is a little brighter than normal, but the tremolo improvement was noticeable in it as well, so it wasn't just speaker differences.
     
    Last edited: Jan 10, 2020
  2. jsnwhite619

    jsnwhite619 Friend of Leo's

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    Oh, yeah, the last two songs after the rolled-tone Hank Williams song were with the amp turned up to 8, and the rest of the clip had the amp on 4. I know that Ragin Cajun will take anything this amp can throw at it, but I think the cap change made it a little cleaner. It's biased cooler than I used to have it at the higher voltage, but it surprised me how clean it is. I'll have to try it through the C-Rex and hotter bias to know for sure, but I've got plenty of clips from before to compare with.
     
  3. FenderLover

    FenderLover Poster Extraordinaire

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    Remember you also went from 275V to 315V. The caps may have helped, but the charge a cap holds has a V^2 term in it. You juiced it up in more ways than one.
     
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  4. jsnwhite619

    jsnwhite619 Friend of Leo's

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    Did a little bit with my Les Paul with Pearly Gates today. First part starts with the same settings as the Tele had - Vol. 4, tone 6. Around halfway when I start War Pigs, the volume was on 10, Tone on 8. Depending on your speaker quality, it has some fuzzy overtone "ghost note" on the bass notes now & then. Is it the phase inverter overdriving? Same thing that was going on in my 5e3 when I was doing a lot of mods & recordings with it. Just a fuzzy double-note type sound when really pushed hard. Any suggestions welcomed.

    My pro tools kept shutting down the recording after I cranked it. I've been having trouble with that lately. A really loud overdriven amp will stop it and it says it can't handle the bandwidth. So, the parts that just cutoff, that's why. I also moved the mic back a bit to see if it helped, and it didn't, but it definitely sounded better with the OD parts. Wish I'd done it there for everything.

     
  5. cobaltu

    cobaltu Tele-Meister

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    jsnwhite619 likes this.
  6. jsnwhite619

    jsnwhite619 Friend of Leo's

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  7. cobaltu

    cobaltu Tele-Meister

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    Another contender would be that 22nF cap that leads to the tone stack. About a year ago I changes this to a 10nF cap in a 5f2 circuit. I was subtle, but I really liked it. You don't really lose any bass, but the amp is noticeably less "grumbly/muddled" sounding; especially with humbuckers.

    But I would start with the PI input cap. It's more of a weak point.
     
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  8. cobaltu

    cobaltu Tele-Meister

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    What input buffer are you recording at? If the input sample buffer is too small, your CPU can crash during recording. Heavy bandwidth demands could do this. If you are not actually monitoring the recording there is no reason for it to be really low.
     
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  9. jsnwhite619

    jsnwhite619 Friend of Leo's

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    Thanks. I'll increase that setting and see what happens next time. I'm strictly home use/self taught with Pro Tools, so any advice is welcomed.
     
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