Blues Junior with C Rex - most effective few mods?

Discussion in 'Glowing Bottle Tube Amp Forum' started by spenno, Apr 26, 2018.

  1. spenno

    spenno Tele-Meister

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    Hi. I have a chance to get a Blues Jr III at a decent price. It has a CREX speaker installed which is mainly why I’m interested. I’m not generally a modder (and have no ability in carrying them out). Now I know lots of this is subjective but before I go on a wild goosechase spending extra cash, I don’t want to mod it within an inch of its life for the sake of it, but what are generally regarded as the most effective 2-3 mods to the amp in terms of freeing and balancing the sound a little, and preserving tube life? As I say it has the Rex and I think the general consensus is that the speaker is the first port of call. Thanks all.
     
  2. slauson slim

    slauson slim Friend of Leo's

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    Save time, grief and funds from chasing down the mod rat hole. Leave the amp alone except for new tubes when needed. For a B Jr. three things work well - master volume on 12, finding the sweet spots with the tone knobs and goosing the tone with an EQ pedal.
     
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  3. spenno

    spenno Tele-Meister

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    Thanks! Although with the bias mod - it would need new tubes far less often surely?
     
  4. PhatBoy

    PhatBoy Tele-Afflicted

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    The bias is fixed, but can be modded.
     
  5. Henry Mars

    Henry Mars Tele-Afflicted

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    My Jr has a C. Rex, I cooled the bias down a bit (I don't notice any difference in the tone and extends the Pwr tube life a bit)... and I changed the reverb tank.
    I usually run JJ tubes in it. The Rex helps with clean headroom and takes away the so called ice pick effect. If you are into modding it it just might be cheaper to get a used Peavey C30 which has a lot more of what I need these days and still has the EL84/6BQ5 sound.
    The Jr sounds best when it is cranked ... I also use it at low volume for open mic nights. It really doesn't need any mods except the speaker depending on which version you get.
    The Jr has it's place ... I use it. I don't know if it is worth modding it heavily though. When you start spending more and more for marginal improvements it might just be cheaper to buy another amp that sounds the way you want it to sound.
     
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  6. spenno

    spenno Tele-Meister

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    Thanks all.
    As mentioned I wouldn’t be modding it into oblivion, I was more curious that whether - with one or two significant simple mods - it could become a respectable amp, rather than a project I would plough cash into.
     
  7. Beachbum

    Beachbum Friend of Leo's

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    I've got a BJ III with the C-Rex speaker and that upgrade did a lot for the amp. Other than speakers to taste I don't mod my amps at all. My take on it is that no matter how much good advice you get about mods there's still no guarantee that you're going to like what gets accomplished. If I don't like a given amp up front then to me it just makes more sense to find one that I do like.
     
  8. maxvintage

    maxvintage Friend of Leo's

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    I built a 12 inch cab for mine and put a Crex in it. I didn't like it very much. I went with a weber alnico 12A125.

    I also put a 12At7 in place of the 12ax7 in the phase inverter.

    Its a great amp for the stuff I play, which is mostly jazz
     
  9. TampaMan

    TampaMan TDPRI Member

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    On the Billm site he states that the one thing to do to get better tone is swap out the Output Transformer for one with more power, this affects tone quality and seems to be the one, major mod that gives the most benefit. See www.billmaudio.com.
     
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  10. JMac52

    JMac52 Tele-Meister

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    Try a 5751 in V1...
     
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  11. LudwigvonBirk

    LudwigvonBirk Tele-Holic

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    If you like what you have, don't fix it as a general rule

    Once the warrantee expires though, those things are super fun to mod*, and you really can make a different and better amp out of it, at least with the older ones. Including my own (MIM earliest version) and friends/associates I've modded the circuitry on 8 or more. Fun to do, you learn a lot doing it. For me, the full capacitor swap/upgrade and the simple tone stack mod to the mids (all well documented) made a gigantic improvement. Mine still has the original speaker and verb pan and transformers, and afaik the original tubes. That said, Fender historically and IMO remains really good at versioning-up their product line at every little price increment and the BJRIII probably has a bunch of solid improvements over the early ones like mine (Fender for sure listens to the community).

    *Wrt hacking and modding the thing: Idk if there's ever going to be (years from now) a "no mods" vintage market for any verison of the BJR. Easy to assume no way, but I remember very well when everybody under the sun hacked up their "phwah, never to be vintage" early 70's Strat, and now a mint one goes for a LOT. Who knew. That said, I don't know of anybody who ever bought a BJR for future investment value, you buy those because they are small cheap fun rockin' machines that you can always easily sell for a couple c-notes if you need some quick cash.
     
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  12. MMARSH

    MMARSH Tele-Meister

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    I think if I was to do one very simple mod that made a big difference in playable tone on a BJr it would be the TwinStack Mod - very simple, just jump two legs of the Mids pot: http://billmaudio.com/wp/?page_id=58
     
  13. SlideGuy123

    SlideGuy123 Tele-Meister

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    2001 cream board MIA model here (the second generation). I did the Billm tone stack, one resistor bias and power supply cap mods more out of curiosity than anything else. I found the tone stack mods made the tone knobs more responsive, so that was a plus. The basic sound of the amp didn’t really change.

    Swapping in a Texas Heat made a big difference- less harsh highs, and a more forward, warmer sound that I like. No way to know if the speaker swap alone would have made the difference. But tubes last a long time, so maybe the bias resistor thing helped. I use JJs because the amp seems to like them - I got some hum and buzz with other brands of 12ax7s. I haven’t experimented with power tubes.

    I’ve also replaced the reverb tank, because the original one quit after 17 years.

    I like the amps natural compression since I play slide. You can easily get a very mid-forward sound to cut through. And I’ve gigged with it plenty of times. It’s fine for small to medium clubs, but we aren’t a screaming loud band. Other guitar player plays a tweed or blackface deluxe, so we’re in the same ballpark for volume.

    Bottom line - I don’t know if you need any mods. I’d say get to know the amp and see if something needs changing. You already have the CRex - that could be all you need. Have fun!
     
  14. MusicCityGrooves

    MusicCityGrooves TDPRI Member

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    Mine came new from the factory with the C Rex, and I played it that way happily for several months. Then I got the modding bug from reading all the forums, so I had the billm basic mods done to it.

    I ran the tone controls at slightly different settings after the mods, but I can't say the amp sounded significantly different to me.

    Based on that experience, I won't mod any amps in the future.
     
    Last edited: Apr 30, 2018
  15. strat1

    strat1 TDPRI Member

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    Keep the amp as is. I hear the CRex is a good speaker. The V3 version has some upgraded electronics. My Laquered Tweed BJ with the Jensen sounds great. No need to look for a non-existing problem that needs fixing.
     
  16. Knowcaster

    Knowcaster Tele-Holic

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    I changed out my BJ speaker for a CRex, changed the tubes to JJ and NOS, did the basic BillM mods. It did improve the tone IMO, but it did not change the basic character of the amp. I was in a cover band and needed to switch between clean and dirty so I used pedals for my dirt, and ended up selling the Junior and buying a DRRI, which I liked better (still have it). I think with the upgrades it would have been fine for rock or blues where I could leave it set on an overdriven tone all the time.
     
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