John Truba's Blog

Catch up with my musings on music and everything else in the world of Valve Amplifiers

Service /Repairs Engineers nightmares .

Recently I had a requirement of a solid state mono amp. that would give me 500w to possibly 700watts for a private project of mine , after talking to a couple of friends , I was landed with 3 old blown customers cast -offs , from  which I might just get a single channel working .  It was a case of   dream on boy , dogs chance or no chance . The amps were of European design made in China using  Double sided " Lead-Thro."  Printed Circuit Boards with the added bonus of  SMD ( Surface Mount Devices ) technology sitting alongside heavy current output transistors  which I've found to be a recipe for disaster  .  As if it is'nt bad enough to find 15 out of 16 o/p transistors blown , one has the anguish of trying to cleanly remove charred/burnt components from the dreaded " lead-thro" holes on the PCB. Seems to me these amps are not meant to be repaired  just replaced  which is the unfortunate saga of todays modern world ( just think of computors ) . These amps are designed to be cost effective , one of them had all 16 output devices in good condition , ie , not blown according to the meter measurements taken , therefore one would assume that the fault(s) lay in the SMD side of things  which did appear blemish free , normally engineers like to see evidence of a "blow-out" , ie , components slightly burnt etc AND hopefully  one side of the amp still working  for reference of component values , then repairs are relatively easy leading to success . On the occasion of trying to get these 3 going , no luck at all . I was given a fourth amp by another friend  which we knew was much more likely to be a runner . This amp had the very same technology  but only a mild condition of  breaking down when pushed very hard  and showed no signs of over-heated/ burnt components .  It is indeed a rarity for me to actually fix SMD problems  ( only about a dozen times have I managed to do this )  But I did on this occasion , I set about doing it the long and hard way , checking  (with no power on) with an ohmmeter firstly I did the SMD diodes  (as they always show up positively when checked in situ)  I got to ok'ing 15  and the 16th diode measured oddly , duly replaced with a 1N4148   ,  having ascertained that the rest were ok  , re-assembly took place , power applied  and "Voila" both ch's performed well  even when pushed hard into 4 ohms  per ch.  Fourth amp lucky  , will have to see my friend ok funds-wise.  Not to labour a point but 25 plus years ago  all amps were repairable this problem did'nt exist  ,  that's so called progress ,  designed by well meaning engineers  BUT  built by the accountants . Bye for now.

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Valve Pre-Amps

A famous actor who we all know and love in his parts in films/TV  once said "Notta a lotta people know dat' "  . The same could be said for one of my products , namely Valve Pre's for recording Mic's/ Instruments  and  in sound tailoring in post production in studios etc  .   About 20 years ago  I was asked to design and build a stereo valve pre-amp. for an associate musician  who had switched from his Reel to Reel tape recorder to a newer digital system , and  of course we all know how clinically clean these can be ( excepting when overloaded with input signal when they turn nasty and unusable  ,  as opposed to tape overload  which can be nice and warm  when driven quite hard )   so he wanted to "warm up"  the signal before recording (digitising) it .  That's where my newly designed / built  unit came to his aid

 Subsequently  I've built many different types of valve pre-amps.  from single channel up to 6 ch. units in a variety of  cases / "Black boxes" , 1U , 2U  & 3U rack formats .  Once when talking to a friend (who was about to audition a unit in his lavish studio  , and being no stranger to Audio electronics )  we quipped the line of  " A piece of copper wire with gain in it "  would be the ideal characteristic  for these valve pre's  . I don't know if I can boast such an accolade for my  pre's  ,  but the people that use my units have said only complimentary things about them  , even I use my stereo pre. to enhance my attempted vocals  ( or should that be Croakles ) .

They are designed and built in 2 formats these days  ,  there's a basic / lo cost  1 U high unit and  a Deluxe full facility 2 U unit . Generally these are customer ordered only , but at present  ( Aug 18 )  I do have a 1U unit  & 2  2U Deluxe  units in stock  ready to be sold  , prices upon application please , thankyou  ,   As most customers know  I offer  "Boutique"  quality at normal cost .

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The passing of a true legend , Chris Larkin

It was with sad sorrow that  I heard of the passing of the legendary luthier / guitarist on Friday 3rd August  .  My deepest sympathies go out to Syra and family . I knew Chris since late 1985 when he was still playing in a band  , we came to realise we had a lot in common - we both played white Gibson S.G. Custom guitars , shared a liking of Rock /Blues music ,  and had a motivating force to further our careers in our respective fields , he , as a  luthier , myself , as a custom amp. builder / repairer new to the Kerry shore's  trying to establish myself  .  Back then he was based in a tiny one room workshop in which his amazing " string "  instruments were built .  Later he had a workshop purpose built at home in Killshannig with studio space above it for Syra , who in her own right is a fabulous artist  .  In early '86  Chris asked me to design and build tiny Pre-amp./ EQ.  boards which I used to supply him with on an ad-hoc basis , in that I could vary the spec. ( with only a phone call  as opposed to a company having to re-jig  tooling etc )  to suit the custom requirement of the instrument he was building at the time . This arrangement worked beautifully well for a good while and we each helped the other out with bits and  pieces and kindly advice on matters guitar-wise .  For it was Chris that always said to me  " you must get yourself a website "  and as the reader knows  I've done just that  .    I  always held and will postumously continue to hold Chris in the highest esteem  , for  he was a true Gentleman  , a  Master Craftsman   and that rarest of all things  , a  lovely human being .

      R.I.P.   Chris  ,  you will be sadly missed . 

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J.T. 30 Valve amps

The J.T.30 valve amps. began their life back in about 1982 (when still in London) badged under the  "JAYTRONICS" logo . Later in 1988 I was approached by a small retailer in Tralee ( who also repaired Fretted instruments)  to design and manufacture a Valve amp. chassis , which after a lot of liasing and consideration would be rated at 30 watts R.M.S. output , which we thought was a good happy medium suitable for all sorts of venues . The idea was  I'd supply amp. chassis'  and He'd supply the cabinets loaded with speakers  and retail them through his Tralee shop .  It was short lived  ,  he did a disappearing act  after only purchasing 1 (one) amp. chassis .  To recoup a potential loss  , I made cabs for both 1x12" combo's and  heads , and til the present time the 30watt design is still popular employing 4 EL84 valves in the output stage  , with of coarse varying features decided by the customer  .  A point of fact , my own "JAYTRONICS"  badged  1x12" 30watter is utterly reliable with it's original  late 70's Mullards EL84's in the o/p stage (still to this day) , how many present day valve manufacturers can boast that ? .

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A new Hello

A new hello to everyone visiting my website , had to happen , myself being dragged into the 21st centuary technology . For a time I resisted (being of the steam driven age) but sensibility prevailed and here we are and there'll be a lot to say , having remained "Schtum" all these years .  The site may be new , but not the products . The first  "JAYTRONICS" products were built back in 1981 in London . back then , one would attempt designing and building anything and everything that was a part of  musical amplification using Valves , Transistors and I.C.'s  (Integrated Circuits) .    Todays world is much different , cost effectiveness , feasability , viability are ALL important for so called commercial success .  I'll always remember an early incident , when having moved over to Ireland in 1985  , and visiting a local music shop in Tralee , having introduced myself  to the staff  (re- my trade)  and being asked could I build and supply  " Lookalikes "  of a simple 4 ch. mixer-amplifier for LESS than the Japaneese imports trade price  --- I suppose they had to ask !! .     So here we are today 33 years later having gone through designing and building all manner of amplification , P.A. Systems , Disco Systems , Instrument Amps. of all sorts plus Peripheral equipment , et all .  I've chosen to specialise in guitar valve amps.  , which is my first love in the  electronics industry , incidentally I do still make Solid State amps on the rare occasion that necessity requires it . As we know it they tend to be cost effective , there's that lovely word again  . See you soon  . J.T.   

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