From: info@turneraudio.com.au   
      
   On Saturday, 6 October 2012 02:27:36 UTC+10, Fabio Berutti wrote:   
   > Dear fellow Rodents, I have not posted anything for a few years but it's   
   nice to see that ol'guys are still around. I'd need just a suggestion: I spent   
   so many years playing with tubes that my home is a total mess and I need to   
   get some of my amps OUT    
   before I can make a new one and carry it IN. The first one to go should be a   
   300B SE driven by triode-strapped 4P1L through interstage transformers. All   
   tubes are Svetlana NOS and all iron comes from Hammond "classic" series. It is   
   completed by its pre-   
   amp, based on a couple of transformer-loaded 27 (a beautiful couple of   
   blue-glass Arcturus). As You RATS can easily guess it is a pretty heavy and   
   expensive piece of audio gear, something I cannot sell so easily. Btw, I'm not   
   making my life out of it, I    
   already have a job, but I wouldn't like to give it away for less than the bare   
   cost of the parts... Any suggestion? Fabio (from Milan, Italy)   
      
   Before anyone would risk paying any money, how about you take several photos   
   and also draw up a very neat copy of the schematics, and draw the F response   
   and measured THD levels so that buyers know exactly what they are getting.   
   Probably nobody will buy because old men wanting to make something like the   
   experience of making it it, if they get time, and so many just never finish   
   what they start, and in fact old men are un-predictable to deal with and there   
   are many gunner-dooz    
   amoung them. But if your amps are made well enough, you'll get prices offered   
   that are just about the worst made chinese junk because  blokes who might buy   
   are nearly all bargain hunters, and wankers who don't have "old mens's time"   
   to fiddle around    
   making anything, they just work and get money to pay other ppl - most often   
   the lowest price humanly possible, often because wifey is trying to control   
   expenditures.    
      
   Despite your descriptions, nobody really knows just what you have for sale   
   after you have described your efforts. You might think I'm a terribly negative   
   person after the comments I made just now but I speak from expereince of the   
   last years since 1994    
   when I began working as a self employed audio tech and began making amplifiers   
   for sale and trading in parts. NOT one single dude ever offered me a good   
   price for anything, nearly all men have an attrocious cuntish attitude to   
   anyone who slaves for long    
   hours making anything. They never wanted to pay the same wage they recieved in   
   their daily job, ie, they valued me like shit compared to how they valued   
   themselves. Over the years approximtely 8 fellows bought transformers and   
   chokes for projects they    
   said they really wanted to make, and I gave them all the free advice they ever   
   would need. Only 1man got a good working amp, and that took him 18mths, and he   
   chose to use the worst cheapest R&C parts he could buy. 3 asked me to build   
   their amp for them    
   because they had no time. I refused, and said they needed to organise their   
   time more wisely and give up crap time parked in front of a TV watching   
   garbage, or playing games online etc.    
      
   So, good luck to anyone trying to sell their hobby results. If the hobby-homie   
   does not have a professional look abut it, ie, good metal work knowledge well   
   employed, it most likely won't ever sell. So don't be surprised if you have to   
   them re-build all    
   properly to sell and put in the hours again for virtually no reward.    
      
   But there are ppl who spend big money on audio, and maybe they have high   
   incomes they don't have to sweat for, ie, they'd get by on 1/2 the wage OK, so   
   if they spend on audio they don't feel their kids are starving, or that this   
   month's rent can't be    
   paid, or that they need new tyres for the BMW this week.    
      
   Meanwhile, be hopeful if you present your stuff forsale properly.    
      
   Out there in FOOLZ PARADIZO land, there are piles of obscenely priced audio   
   gear not worth 2 bob.    
      
   Last month a guy brings me a pair of Jadis SET 300B amps made in 2004. They'd   
   been blowing fuses and playing up. He'd bought them cheap at $6,000, a steal,   
   because he said they retail new for $19,000. Well, I was asked to check them   
   right out before he    
   continued use with his Coral 10 Beta speakers. I find the workmanship under   
   the chassis pretty awful, with parts hanging around in mid air because they   
   don't believe in terminal strips or boards. The point to point wiring looks   
   like its all been wired in    
   China. I thought maybe the shiny brass Jadis badges with 'Made in France' are   
   also made in China with everything else, but just where the amps are made   
   doesn't matter these days, they all sink to the lowest common denomimator of   
   quality.    
      
   I find there's only one heater supply for both paralleled 300B, and no   
   individual bias adjustment possible. The single Rk was 300 ohms, much lower   
   than it should have been for 2 tubes, but hey, didn't stupid Jadis know you   
   must have separate R&C cathode    
   biase networks to keep Ia similar for parallel tubes? No, they don't know   
   this. Then I find they must have found the output power was a bit low, maybe   
   12Watts because B+ was a bit low with a 5U4 rectifier, so they strap Si diodes   
   across the tube rectifer    
   socket to lift B+, but make no change to Rk. So this possible higher PO, but   
   only if the grid bias is able to be balanced because I found one 300B idled at   
   40W with the other at 12W, all over the joint, and part of the cause for fuses   
   to blow soon after    
   turn on with one amp.   
   The 6SN7 with two exactly identical cascades stages barely was able to make   
   the drive voltage needed. The single biggest problem was both OPTs for the two   
   monoblocs, with consecutive serial numbers.    
      
   The Jadis OPTs have NO air gap!   
      
   I got one amp biased correctly after re-building the driver amp and adding a   
   bias balancing circuit with pot, and found I could get 17W at 1kHz, but not   
   very clean looking. But if I adjusted F down the OPTs showed visible OPT core   
   saturation distortion    
   of about 5% at 250Hz. Yes, 250Hz, not 20Hz, which we might expect from a   
   $19,000 and OPTs weighing 7Kg. The core saturates so badly below 250Hz that   
   when I drew graph of max PO governed by a line where THD < 3%, only 1 Watt was   
   possible at 50Hz. Jadis    
   buyers should thus phone up Jadis to ask them for a refund of say $15,000,   
   because most bass performance was missing!Anyway, I then measured the OPT   
   primary L and found only 1.0 Henrys. I then turned off the amp so no DC flowed   
   ( 150mA ) and connected an    
   external source of Vac from a power amp and current sensing R. I measured 88   
   Henrys at 10Vac at 50Hz.    
      
      
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