Vintage Traynor YBA-1 mod to Plexi specs?

Discussion in 'Amps and Cabs' started by doc, Mar 29, 2008.

  1. doc

    doc Member

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    Any of you mod your vintage Traynor YBA-1s almost completely to Marshall Plexi specs? How did it work out? I'm planning to mod mine, but not sure if I want to just change the pot values and mod slightly or do the Full Monty. Sounds pretty decent with no mods at all, but needs a cap job anyway.
     
  2. Tone_Terrific

    Tone_Terrific Member

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    My .02-
    Leave it alone, unless you know exactly what you want, how to get there, that you will be happy 'there,' and have all the tech knowledge and parts to not mess up.
    Otherwise...pedals.
     
  3. doc

    doc Member

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    I don't think I'll have too much trouble getting there - I'd done enough repairs and mods on other amps to get it done right. I've never had the chance to play a real Plexi and don't know anyone who has one, but I like the recorded tones I've heard. I really can't afford to just hunt down and buy a Plexi. I figured with the knowledge and experience on this board someone has probably played both the real thing and a Traynor that has been skillfully modded. I usually tend to agree that its usually a bad idea to irreversibly mod most amps, but the Traynor is still affordable and available as well as very close to the Plexi in circuit design, so its tempting to try it. It wouldn't be like trying to turn a tweed Fender into a Mesa Rectifier or some other similar Don Quixote misadventure, hopefully more like me modding my Fender Vibrosonic Reverb preamp to blackface Twin specs, the results of which I'm very happy with.
     
  4. bolero

    bolero Member

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    there was a great website, sean kilback...traynor tweaks....explained it all



    there is not much difference....a friend changed his YBA-1 volume pot from 4meg to 1meg & was satisfied



    fwiw I have a stock YBA-1 & it kicks rhinocerous balls the way it is....I also have a '66 jtm100 that sounds great; there's not much between them

    ah, here we go, I just googled it:

    http://www.kilback.net/traynortweaks2.htm
     
  5. Sparky6string

    Sparky6string Member

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    I haven't even changed the pots on mine and don't see a need to. I did change the electrolytics though. I agree that nothing need be changed on them. Great amps.
     
  6. sliberty

    sliberty Member

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    There were several different circuits for the YBA-1. Mine was the Plexi circuit with some slightly different values. It sounded so much like a Plexi, that I saw no reason to mod it at all. I did the 4M to 1M pot mod anyway though. It mainly gave me a little more clean before the crunch kicked in hard. Do the pots, and leave the rest. The differences will be hardly noticable in my opinion. But defintely get an attenuator to you can crank the sucker up a bit more.
     
  7. soldersucker

    soldersucker Member

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    I am from Traynorville just far enough away from Tarana that people aren't too hip to them and they are cheap.Had maybe 11 of them over the years,the two ive kept are #0018 for collectors dibs and a 68 that just sounds incredible.The 68 has been my plexi/bassman guinea pig over the years.And i have a real 68 50 watt too compare too so here ya go the cacaca changes-
    4meg vol-1 meg remove 1000pf brite cap
    -presense pot rewired to 5f6a scratchy spec
    -270k mixer resistors with 560 pf brite cap on input II
    -tone stack .022x.022 -500pf - 33k -slope
    -can't remember exact feedback resistor but i'm thinking 56k
    -jumpered V1 internally to allow channel mixing-
    -bias pot
    cooling Fan for ***** and giggles.
    It is still a Traynor just a little more refined and tuned too guitar and not bass.Here's #18-guts-
    [​IMG]-with a bud a rare Ampmate reverb JH1-1-
    [​IMG]
     
  8. doc

    doc Member

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    Thats the purtiest Traynor I ever saw. Thanks for posting.
     
  9. guitarded_1

    guitarded_1 Supporting Member

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    I had a YBA-1 modded to plexi specs, including an OEI plexi repro tranny. It was a cool sounding amp, but didn't sound much like a plexi to my ears.
     
  10. soldersucker

    soldersucker Member

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    You are right even with the mods it still doesn' t have that snarl that my Plexi has more like a Fender/hiwatt/Marshall threesome that is Traynor.Don't get me wrong it is classic and stands up to any of those benchmarks but it isn't 100% identical to anything else.
     
  11. rockinlespaul

    rockinlespaul Member

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    Vintage Guitar has a article on modding the old Traynors. It was a few issues ago I believe. Having said that, my modded 1969 YVM PA head is a plexi killer! :AOK

    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
     
  12. ROKY

    ROKY Member

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    Haven't plexified mine(a '66), either; just snipped the bright cap.

    Will probably do the 1 meg pots at some point & add a smaller value brite
    cap ..

    As it sits now(I've had it for around 6 yrs) it sounds pretty Marshally to
    my ears. The Hiwatt comparison I don't quite understand.

    My YSR-1 reminds me more of a Tweed Fender, but my YBA-1 is pretty
    Marshally voicing-wise .
     
  13. lcjc800

    lcjc800 Member

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  14. Oatman

    Oatman Member

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    I've had a '71 YBA-1 for several months now, and love it.

    I'm a little confused by all the comparisons to a Marshall Plexi...

    I thouht "Plixi" referred to a whole bunch of Marshall amps from a particular era (all having the gold painted Plexiglas control panels eventually replaced with metal panels). Don't these different models sound different (other than the JMP 50 and JMP 100 which are pretty similar)

    I thought the YBA-1 (in the earlier Bassman-like circuit) was specifically like the JTM45 which was quite a bit different from the later JTM and JMP plexi models???

    Basically I'm asking shouldn't the YBA-1 sound a bit unlike those other plexis and more like the EL-34 Bassman-like earlier JTM45? Basically less gain and brightness like the earlier JTM45 compared to the later JMPs. Or am I hopelessly goofed up here?
     
  15. DGDGBD

    DGDGBD Member

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    The earliest YBA-1's had a tube rectifier hence the comparison to JTM45. Those are pretty rare however, and when folks talk of their modded YBA1's they are usually talking about the solid state rectified models. All of the 50 & 100 watt marshall plexi circuits are more similar to one another than they are to the YBA-1. Likewise, the 5F6A tweed bassman circuit is more similar to JTM45 than to the earliest YBA-1s. I think you're correct in that the gain is similar to the older marshalls and not the later JMP's.
     
  16. JDW3

    JDW3 Member

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    I modded mine to 1987 Marshall specs. It's a '68 YBA-1. I also replaced the filter caps and added a bias pot. I was trying to get maximum gain out of it without doing irreversible mods. I succeeded in making it overdrive pretty nice but no, it will never sound like a Marshall because of the huge transformers. You don't realize that until you hear them side by side. I could put the old parts back in easily.

    It's fun to tinker with it. I have a 100k NFB resistor that I think I need to reduce. The cathodes have been split. But not really too far removed from a stock YBA.

    I have a '68 YSR-1 that to me, sometimes just kills the YBA at volume. Sweet cleans and nice compressed high gain cranked. But, too compressed.

    Also, don't forget the Airbrake!
     
  17. Brenna23

    Brenna23 Member

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    Anyone who has one of these wonderfull amps that want to make it scream check out Rocknrollamps.com and be blown away. They sound even better in person.:dude
     
  18. doctorx

    doctorx Member

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    I have two YBA1-A's and the only thing I've done is recap them, which they didn't really need. I would vote for keeping them as they are, because even with the mods it won't sound like a true plexi. The sound great as they are. Try new tubes, jumping the channels, and diming it except for the bass control. Throw a tube screamer or similar in front of it and I think you will agree. It doesn't matter if you use a Strat or LP.

    I run my two YBA1-A's like this through a stereo cab with a stereo chorus and it is Tone Of The Gods.

    You can jump the channels using a short patch cord externally or here is how to jump the channels internally.
     
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  19. maize

    maize Member

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    You must follow your ears and I can guarantee my Traynor 1973 YBA1 sounds as good and even better than a Plexi. Everyone hypes the Plexi which is no more than the Marshall's of the early time period w plexiglass fronts??? Marshall's were not as solidly constructed and in a pro amp designers hands a Traynor YBA1 can put out tone that any Plexi fan would die for. Some say it is folks bragging about their less expensive amps but I can play through anything I desire including a Dumble and I choose my modded YBA1. It's in the tone not the wallet!
     
  20. parkhead

    parkhead Member

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    The reason they don't sound exactly like a plexi is that the power transformer and supply is much stronger on the Traynor

    Marshall had difficultly sourcing High Current power transformers
    so the power is bouncing all over the place on a Marshall
    on a Traynor the supply is rock steady ...

    there are ways to tweak the power supply so it behaves more like a plexi
    Lowered filtering is one ..playing with choke values is another

    p
     

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