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John Truba's Blog

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

A red Tape matter or should that be 3 and 7 .

Since learning the resistor / capacitor colour coding  system in early 1960's  I've used it to great advantage in my domestic life as well as ( obviously ) in Electronic aspects , you know the one I mean , ie , Black - 0 , Brown - 1 , Red - 2   and so on .  In the Electronics Industry when " wiring in " or " Looming up "  cables or wires  , one uses the colour coded system  type identifying Sleeves or Markers  , but when you're dealing  cables or wires that are pre-wired / fixed or have connectors already attached , then the use of coloured insulating tape can come into play . But this is where we hit a stumbling block . I've yet to find Orange ( 3 )  and Mauve / Purple (7 )  insulating tape available commercially  , ironically  the colours have been available in Mic cables and such like , but Not in " Insulting " tape ( insulating tape for the non-cynics out there ) . In my own workings what I do is , for 3  ( orange )  I use 1/2 width tapes of red ( 2 )  and  yellow ( 4 )  therefore the happy medium being 3   , and  blue ( 6 )  and grey ( 8 )  giving  a happy medium of  7  . I find this works perfectly because for the normal colours used  one uses the full width of tape  and the " made up colours " in 1/2 width .  

 So Please  " SELLOTAPE"  , " 3M"  and other tape manufacturers out there , give us this day our daily Orange and Mauve / Purple  insulating tapes  , and in anticipation of Mr Clever Dick out there  I've not been able to find them yet even if you have   . !!!  

  The system of colour coding can sometimes outwit ordinary numbers , when say used in potentially "dirty" situations , such  as in a multi-cylinder engine for spark plug recognition , where if a  numeric system was used  grime/grease  could make a dirty 8 look like a 3   or  a dirty 4 look like an upside down 7  and so on . With the colours used for a V8 engine  it  would be Brown -1 , Red - 2 , "Orange" -3 , Yellow - 4 , Green - 5 , Blue - 6 , "Mauve" - 7 and  Grey - 8 , and Bobs your uncle and  no misfiring of engine , I've used this appraoch myself and it's ok  . For Microphones  in a Recording studio  such as that  AKG C414  that would be Yel / Brwn / Yel  , that Shure SM 58  would be Green / Grey  and so on .  All the dark cabled  leads to and from Mixers / Recorders / Outboard Equipment  where only a silver or white marker would do ( you try and find a good one that doe'snt immediately shed its colour when disturbed )  can benefit from the tape system , Of course if you have white cables then you can use coloured Magic markers to do the job , but bear in mind that over time the ink does fade .

 Back in the day when I was working in my first job ( an apprenticeship ) with a company called  "Lustraphone "   ( we pioneered Europes first Radio-Mic systems )  amongst all manner of jobs I was working on  , I sometimes had to work on M.O.D. stuff  , this was all right angles in wiring , neatness personified , daily checks by the man in a black suit , white shirt and dark tie  there was a protocol of colour coding for Valve stuff where only Red was used for high-tension , Black was Chassis/Negative , Green was Valve i/p grids , Blue was Valve Cathodes  , Twisted Green for Valve heaters  and a few other codings which I 've forgotten  . But alas todays modern approach seems to have ignored all the sensibilities of yesteryear  , so in some circumstances any colour could be high-tension , point here is never assume , you know , it makes an ass out of  Blah Blah Blah ,      See you soon .        

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50 year + guitar solo enigma unlocked .

If you were a teenager in the 60's as I was ,  doubtless you probably watched the "Monkies"  TV shows  which were the rage for a while , featuring songs , antics  et all . One song which heralded quality was " Last train to Clarkesville"  which had (has) a beautiful lead solo  which proved to be an enigma to the majority of us guitarists ( Yeah there's gonna be the clever dicks out there who sussed it out in 5 minutes )  but I personally did'nt know anyone who had it off pat .  We thought along the lines 2 or more guitarists doing a ascending G modal movement  , but try as I did  , could'nt figure it out , till last week  , through having to work it out for a new band project I'm doing and the other guitarist checking out You Tube  ( I've never done this before  always worked things out from just listening , god knows what rock I've been hiding under )  and telling me yes the guy that did the original solo has  done a video on it  . Wonderful !!!  I checked it out  and yes it was a chap called Louie Shelton  , it was his entrance to the world of session-work apparantly .  Within minutes of seeing this video  it all became patently clear  and the solo has been nailed  . Previously in a London based pub-rock band in 1977 we tried to do this very number  but were totally confused  ( 3 guitarists in the band )  ironically that is the amount of guitarists it took to do this wonderful sounding solo . One playing alternating  Gmaj7 to Fmaj7 chords and back again , the second guitarist playing a very simple motif  at the 10th  fret at the  top  E and B strings  and the main man himself  ( Louie)  playing arppegiated  inversions of  G and F ascending and descending  and finally ascending again  to what was considered by everyone I knew  to be a cracking good solo . We had thought this was done by a pedal steel player in conjuction with a standard guitarist because it is a very confusing solo to listen to , all sorts of guitar sounds emanating   so one would'nt be absolutely clear about what's actually going on  .  It's an absolute breath of fresh air to finally know how it was done , just imagine that they went into the studio probably not knowing what's expected of them  and coming up with this class of a solo , give me this sort of playing any day  to the boring crap done by todays modern "Tappers"  not forgetting the "Wammy bar"  merchants all trying to do a million notes a second   bumble bees and wasps stuck in a jar  come to mind .  Now where's that 14 gauge top string I was about to fit to my 335 .

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50 year + guitar solo enigma unlocked .

If you were a teenager in the 60's as I was ,  doubtless you probably watched the "Monkies"  TV shows  which were the rage for a while , featuring songs , antics  et all . One song which heralded quality was " Last train to Clarkesville"  which had (has) a beautiful lead solo  which proved to be an enigma to the majority of us guitarists ( Yeah there's gonna be the clever dicks out there who sussed it out in 5 minutes )  but I personally did'nt know anyone who had it off pat .  We thought along the lines 2 or more guitarists doing a ascending G modal movement  , but try as I did  , could'nt figure it out , till last week  , through having to work it out for a new band project I'm doing and the other guitarist checking out You Tube  ( I've never done this before  always worked things out from just listening , god knows what rock I've been hiding under )  and telling me yes the guy that did the original solo has  done a video on it  . Wonderful !!!  I checked it out  and yes it was a chap called Louie Shelton  , it was his entrance to the world of session-work apparantly .  Within minutes of seeing this video  it all became patently clear  and the solo has been nailed  . Previously in a London based pub-rock band in 1977 we tried to do this very number  but were totally confused  ( 3 guitarists in the band )  ironically that is the amount of guitarists it took to do this wonderful sounding solo . One playing alternating  Gmaj7 to Fmaj7 chords and back again , the second guitarist playing a very simple motif  at the 10th  fret at the  top  E and B strings  and the main man himself  ( Louie)  playing arppegiated  inversions of  G and F ascending and descending  and finally ascending again  to what was considered by everyone I knew  to be a cracking good solo . We had thought this was done by a pedal steel player in conjuction with a standard guitarist because it is a very confusing solo to listen to , all sorts of guitar sounds emanating   so one would'nt be absolutely clear about what's actually going on  .  It's an absolute breath of fresh air to finally know how it was done , just imagine that they went into the studio probably not knowing what's expected of them  and coming up with this class of a solo , give me this sort of playing any day  to the boring crap done by todays modern "Tappers"  not forgetting the "Wammy bar"  merchants all trying to do a million notes a second   bumble bees and wasps stuck in a jar  come to mind .  Now where's that 14 gauge top string I was about to fit to my 335 .

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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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