hi......i'm looking to upgrade the O/P transformer in my plexi lead 50, i installed a Mercury magnetics O/P tranny and choke in a Marshall DSL 50 a coupla yrs ago and was very impressed...i'm hopeing a better grade of tranny will add that bit of sparkle my amps missing...

i'm wondering if anyone has swapped out the stock Ceriatone model and if it improved the amp any?

i know of Merc/mag's but are there any other brands i should consider??

and are there any UK based manufactures worth taking a look at?? shipping & import duty's a pain in the ass!!!

thanks for takeing the time.....ray.

hi mate.......these days i'm sure it's vintage 30's ( sound like crap to me too) it's what dennis Cornell loads his Robin Trower sig amp/cabs, i've always thought it was vint 30's, even before knowing Cornell amps used'em....but over the yrs he's prob tried'em all...the vint 30's handle  bass better than most, and as RT uses the Middle p/up on the strat the most it make's sence really, not only that!! as i understand it he tunes his guitar to D when playin live, again the vint 30's help this!! one of the main factors of his tone is he drives his amps hard without the gain kranked so it's a pretty clean tone, he uses fulltone pedals for extra power...there are clips on youtube with trower and he's pretty open as to what gear he uses...but the main points are, middle p/up, amp pushed hard, vint 30's, big strings, tuned to D when live like the Rockpalast shows on YT...The D tunning could well be due to who he's got on vocals though!!!

rock 'n' roll..

sorry for any confusion guy's.....i did list eveything that had been done to the amp to the best of my knowlege... a jtm 45 running el34's and putting out 50+ watts (not switchable 45/50) would class as a mod, i'm sorry for this...you must understand that i'm asking questions because i don't know how these things work, right???

hey myfriend......i'm not interested in being able to switch between the ss and the valve rectifier....i just want to return it to the jtm45 (30 watts) rather than the 50 watts it's running at now....

so am i right in thinking that i just put in a valve rectifier and bias to whatever tube i use?...

will this also correct the ohm's selected??? ie the 16 ohm setting is 16, 8 is 8 etc etc...the miss-matching must have been a huge factor for the mod to work without re-wireing or replaceing the trani right?

if it helps you at all to see pic's of the amp i'll be more than happy to send some if you wish?

thanks for your time/help mate...........ray

hey mate........i'm asking for help with regards returning the amp back to it's JTM45 form....

i guess what i need to know is.....

1...do i just pull out the ss rectifier and install a valve rectifier??? and it's back to being a jtm45???

2...does it matter much what output tube i use, el34's or kt66???
 
 Denis Cornell builds a plexi 45/50 with a switch to sellect either the jtm 45 (valve rec) or the 50 watt (ss rec)... but i can't find any other info on the mod, i though it would be quite common given the amount of mods there are these days....

thanks again buddy............ray.

guys i have handwired JTM45 which i took to my tech a couple of yrs back needing more volume, he switched the valve rectifier tube for a s/state rec, replaced the KT66 with EL34's and i'd got a 50 watter,  the ohm selector does have to be mis-matched to opperate correctly, the 16 ohm setting is now really 8ohm & 8ohm is now 4 ohm etc etc basicly i have to set the amp at 16 ohm to match my 8 ohm cab.....i don't remember anything else being done as i was there.....

oh!! i do remember a resistor being added to the bias pot!!! could that be due to the change of tube?

anyhoo, i'd like to return it back to it's original JTM45 form, and i'd quite like to do the job myself...eversince i got my Ceriatone plexi 50 i've shown more interest in how my gear works.....

oh!!! one last thing, i've searched 'n' searched for any info on this mod 45 to 50 etc etc and can't find a thing, have any of you guys herd of this mod?
                                   thanks for your time....

Guys.....i'm sooooo sorry!!! this problem with my amp was solved (kinda anyway) just a few weeks after my original post (cry for help)... i did write all the info on the matter soon afterwards but, and it's a BIG BUT!!! i must have stuffed up and deleated it instead of listing for you guys to read, again i'm so sorry as you guys helped me loads and it's not right that you didn't get thanked....
         
          anyhoo, so my plexi 50 was a little dumb sounding, almost like my guitars volume was at around 6 when it was cranked...i knew something was wrong!!!! that rich smooth bite was missing and it lacked in REAL TONE like i'm used to....
         
           so, i contacted Nik many times along with help from you guys, i kept trying different tubes (mullards,brimar etc etc all good stuff) and new leads/cables etc etc everything i could think of, and then i tried again and again etc etc for days 'n' days...while still tryin stuff the main fuse blew for some reason unknown to me????maybe a winged c tube had gone faulty? so that was replaced and i loaded in a pair a EH EL34's that where well worn and kept as spares, i didn't want to knacker good tubes....anyhow, i fired her up and WOW!!! something had changed for the better in a big way, there it was, just like that!!! fantastic sounding amp, now, this is where i get lost because i'd tried every tube i had many many many times...the bias was spot on too, about 36mv.... i re-loaded back in the winged c's and they worked great, no problems what so ever, this amps used every day and it's fantastic.......so although the problem went away i don't know and neither does Nik know what the problem was, like i said, i tried all and every tube time and time again, nik did say a valve base maybe at fault? they all looked perfect to me....whatever caused the fuse to blow kinda (in my mind) fixed the fault if that makes sence?        thanks for helping out guys and takeing the time.....anyone thinking of buying a plexi 50 should just buy it!!!! without a doubt!!!! this is my main amp and it's shit hot and as good as most original plexi's i've had/played...

thanks for your time and help............ray.

hi buddy.......no, not yet!! i hoped it was something i was doing wrong, and i could fix it...i'll now drop nik an email as i'm sure it's no fault of mine.....do you have any idea's, the presence control seems to make no difference wheather at 0 or maxed out on 10...
thanks for your time....

hi bud.........yeah! i have a multi meter....from pin#8 to ground i'm getting 34mA from the first & 40mA from the 2nd...is this normal? something else to add is, i've sat with it for ages today and to my ear, i can't here any difference at all between the presence conltrol on 0 or 10, the rest are a little better though no where near the amount i get from my 78 2203...it's night & day realy....
thankyou so much for your time mate, your a gentleman and a scholer.....

hi mate.....still looking into it....it don't look as though there are any faulty parts, could it be it's just not what i'm used to??? i've had original JTM 45's and plexi 100's but never a plexi 50, the closest would be a 71 metal face plate 50 watt model which i've heard have more gain, could it be that i'm just missing that extra gain???the extra bite???
cheers...

hi buddy......i'm getting 433 plate voltage..... please understand, i know very little about electronics, i've messed with pedals and changed out faulty parts on amps inc a transformer once but thats just a direct replacement........i use a Weber Bias Rite and it's from this i get the readings...useing their methods i'm getting 28mA low & 48mA high and been setting the bias between 36-40mA...
thanks......

Hi...i have plexi 50 lead with the PPIMV mod...i've owned it from new(2 months) and i've tried everthing i know to maybe improve the overall tone...
           1st, tubes, mullard, JJ's,Seimens,Brimar & winged C's which are in there now along with brimar pre's...best so far!!!
           2nd, Speakers/cabs, Celestion g12h's Originals 2X12, G1275 2X12 and an original 68 100 watt plexi cab, plug a donkey in this and it sounds great, but not the ceriatone!!!!
           3rd,Guitars vintage les paul & custom shop strats...
           4th, pedals F/tone,analogman,Foxrox etc etc all good stuff..pedals help of course but i don't want to have to use pedals to get good tone!!!! but even when useing say, an OCD, when i lower the guitars volume the tone gets real dull/muddy???sounds like crap!!!even with the fenders single coils....
       
      i'm alittle lost guys, is there somthing wrong with the amp??? to me it just has NO ZING!!! Like the guitars volume is around 6-7 or the tones down to around 5-6...i'v had so many marshalls 60's onwards and still have a 70's 2203 which has more zing even with the pre turned down below half mast....i know old marshalls and they sound VERY REAL and have never been able to have the presence & treble above say 6...with this ceriatone i have both the Treble & presence at full tilt and i need more!!! alot more!!!

      i'm hopeing there's a problem if i'm honest, it can then be put right....i realy want this to work as it sure looks the part, build quality is outstanding...there has to be something wrong here.....

      any help at all would be great guys, i know i'm in the right place....

      thankyou for your time.....