Genral advice

General Advice

COMPONENT CHOICE

What do you need when constructing a project :
· soldering iron min 25 watts
· solder 60/40 max 1mm and if you insist 3% silver is admissible
· sponge to regularly clean soldering iron, when soldering
· remember that solder must heat up until it is flowing and then cool
· down slowly , otherwise you get cold joints

Most frequent beginners error :

Badly stripped wire , the wire breaks off after a while and however good the solderjoint , the contact is gone.
A correctly stripped wire , is when u use a stripping tool or knife and cut the plastic away without even scratching
the conductor , check with a magnifying glass ( that's what its for )

What do you need in a basic electronic workbench enviorment

Consider those items listed here in order of priority

Required --------------------------preferred

· Soldering iron 25 watts -------station 50 watts with right solder tip & sponge
· Mechanical 3 rd hand ---------with magnifier
· Cutter tweezer, screwdrivers ,wire stripper ( tools)
· Basic multimeter --------------digital 3 ½ dmm
· Dummy load
· working lamp -----------------Loupe lamp
· -------------------------------Capacitance & inductance meter
· Speakers & cd player & radio
· -------------------------------Variac (digital readout)
· Power supply 0-30v 0-3a fully adjustable with digital read out
· -------------------------------Scope 2x20mhz
· -------------------------------Frequency generator (digital read out)
· -------------------------------High voltage powersupply
· -------------------------------Tube tester
· -------------------------------Distortion meter

resistors :
forget carbon ( except for the romantic ) , wire wound ,vitreous enamel ,std metal film or
substrates use metal film 1% if on a budget ,remember that
std resistors are not made with high voltages in mind or hi-end
applications , they are practically all magnetic and inductance varies
with value and temperature (rarely a problem for hi end) oure choice is
the dale 1 watt it is a fantastic resistor , non magnetic ( most are 95%) ,
low inductance (only the caddock is better ,but then again not every
caddock just the expensive ones) , high stability , high voltage (500vdc & 900 vac),
high accuracy and low noise if budget is not a problem try caddocks (MS244 series is the best) this is space technology at is best if you need more then 1 watt : parallel dales (it also reduces inductance by the way which is so low its only a problem in the Ghz range )
or use dale 5watt ( excellent non magnetic wire wound , I am sorry but this is really
a good wire wound type very suitable for high voltage applications .

potentiometers :
forget about alps,noble,tdk,penny&giles,bourns,vishay,piher ect the only
extraordinary one is the panasonic precision plastik film , except for
subjective quality there is a technical reason to explain why this is such
a good potentiometer , the tolerance between left and right channel is
within 1dB (std guaranteed tolerance ) and usually is better then 0.8 dB
which is extraordinary (some of the others are quite good but not as good
and certainly more expensive)
for mono pots a cheap high quality alternative are the cermet types by vishay & bourns

stepped attenuators
are not bad , can be great but i am not very fond
about them because they require many components , and lots of solder
joints and then there is the switch that has to do a constant job contact
resistance wise and then the least mentioned fact is one of capacitance measure it ,
you'll be surprised (this is not dramatic for it limits emi and its the Mhz range
, so no real damage done), and there is the price .(but I agree it's a nice feel all those
clicks just to set the volume , and the grin when you're just in between 2 clicks .

signal selectors :
well if you use cheap ones , always ground every 2nd tap and put signal on
the uneven ones or use expensive ones silver plated contacts are not as good
as gold plated from a mechanical point of view.

capacitors :
well there is nothing wrong with them , spend your money wisely , to filter
out hum you need large values , then decouple with 1/100 of the value use
good quality , avoid MKT , (some pre amps costing as much as 15000 us$ are
packed with them : totally wrong) avoid to pay excessive prices for brand names
in electrolytics , avoid tantalum and stick with industrial grade electrolytics when
possible de coupled with decent MKP,MPP .For signal use MKP,sink foil MKP (expensive but cheap compared to other brands copper and silver foils
( note the purpose of the foil is double ,but primarily it is for vibrational purposals
that benefit is maximum that's why paper in oils are so famous , the paper in oil
is virtually non resonant while MKT are the worst and any foil will dampen
enough , so don't overpay).
for the freaks there is black gate , personally i find it very expensive
but it is indeed a very good capacitor , it's main quality comes from the fact that when the music passes through the capacitor it sees an equal resistance on both its alternances ,positive as well as negative so no distortion is added , this where clearly electrolytics fail because they are polarized and don't like reverse voltage , but all in all I am very happy with the results obtained from conventional electrolytics that are properly de coupled with mkp and mpp . if you can afford the black gate then use it .
see capacitors price list

transformers:
double c cores from lundahl are great , I will publish some measurements taken by me and customers
and I will use plitrons way of measuring : virtually unloaded (1milli watt) and just the generator on it
and then I will also claim hundreds of Khz bandwith , and super quality factors .
the Lundahls are non potted and are truly beautifully wounded and very reasonably priced
note that an article appeared in sound practises : to pot or not to pot (with epoxy filled )
& the winner is the unpotted version but we will supply covers for the output transformers ,the small ones you can allways mount in the inside.
For people on a budget we have toroids (made in the same factory as the
megabuck ones that advertise in GA) as far as power transformers go :
toroids , have lower strayfields and are more efficient and easy to mount
and they will not vibrate at line frequency ( any power transformer is good
as long as regulation is ok & you are aware of its strayfields )

wires :
well this is a highly sensitive issue , solid cores seem the way to go be it silver
or copper (I prefer copper but this is personal and cheaper),teflon coated is less good ,
( they create a temp shock to get the Teflon bonded,
the wire is heated to about 400 °C and then teflon is applied and then immediately
cooled very fast to 100 °C) so just a lacquer seems better (they let the wire cool
slowly, no forced cooling )we offer very sensible priced silver solid cores use for
signal carriyng wire & do not forget that the music flows through the first
powersupply capacitor as well (that it sees), that's why you should by pass these
with smaller caps or use black gates wkz types.(and cable )

tubes & tube sockets:
well we dont offer yet the best tube sockets , they would be molded in teflon
and use goldplated non magnetic contacts , if someone finds this please share ,
what is really important is the way you mount them , use o rings and rubber to
isolate from vibration.
Tubes well in short the popular types made by the millions are truly great ,
the new ones are sometimes great and sometimes not to good , all companies
have there strenght and weaknesses.lots of tubes lend themselves to excellent designs , you don't have to stick with the classic ecc81 ,2,3 series . ( but we the designers will use them and the commercial critics will tell you its not a great design because it uses a tube no one has ever heard of ( meaning themselves ) a small

comparison of tubes
examples :
avoid in our opininon 300B from sovtek,jj or tesla ,chinese expensive versions
(the cheap are very good ) , WE (too expensive ,think of it as if it had no brand
and you would compare it ,would you rate it as high as the press claims it should be ? ).
chinese 211 & 845 are not great but they are improving steadily all though that
the only decent 845 is made by cetron but costs a lot (ps many megabuck power
amps from audio.... use cheap 50us$ chinese version) and this is truly unacceptable ,
but clients buy so i must be wrong .
avoid chinese EL34 , sovtek EL34 (if voltage exceeds 450), sovtek 6L6gt.
(cheap but not hi-end).
avoid sovtek ECC88/6DJ8/6922 for critical MC applications
avoid 6AS7 & other pass tubes , they have poorly bias stability and need feedback to
stabilize so not really audio suitable.
Krone and avvt make some excellentn high tech tubes , but not every model is a success and svetlana in general has a build quality that is really nice .

psupplys:
current sources and shunt regulators are useful but lots of electrolytics are
good as well , chokes are useful and ultra fast soft recovery diodes with damper
resistors are great (the damper resistor serves as a surge limiter , emulating
tube rectification ), otherwise use tube rectifiers , unregulated extremly well
pi filtered supplys are trully great and choke input filtered powersupply's are the top ,
but labor intensive . PP design doesn't require
ripple free power for the power stage just for the first stage in its small signal amplification, commercial amps use resistors to filter but a choke is much better . SE amp designs are much more critical , here you need to really kill ripple , use lots of
electrolytics and pi filters & chokes ect.
grounding star ground or think signal wise every signal has its ground so keep cool and rewire if necessary. (signal follows its ground).

Rectifiers
One can use tubes to make from AC current a DC one, the sound is better.
Why is this so ? Because the tubes don't produce any high-frequency spikes,
Unlike a diode, and tubes have a high internal resistance.
But if you use a Ultra Fast Recovery diode together with a damping
resistance you get almost the same result, simpler and cheaper.
Or have a look at my hybrid tube rectifier designs combining the best of both worlds .

SRPP or mu followers:
i dont like them , very good live sound but too aggresive pronounced S sounds, maybe I have not heard a
good one yet , but in combination with very warm sounding amps (the warm sound is usually a result of
automatic cathode polarization with an electrolytic capacitor that is non by passed .)
adding an srpp can add a spark of freshness and make the amp sound more lively.i am more a fan of traditional choke loaded circuit , but tube loaded or solid state loaded doesn't make a difference to me.

chassis
use non magnetic chassis , aluminium , copper and some stainless
steel alloys are great but difficult to work with use good quality rubber feet ,
try to stabilize the underside of the chassis to avoid micro phonics like a
suspended sub chassis (ect oil dampers and spring can be found on demand =
only for the most demanding freaks this will be necessary or spikes ).

connectors :
use good quality (nothing fancy )gold plated rca plugs , the male version should be easy to solder and the female version should be strong enough to mount and tighten them without the tread breaking.

security :
the chassis should all ways be earthed .(at least to its own power supply )
fuses use only when absolutely necessary ( they degrade the sound quite often ) ,
If possible use automatic fuses ,
Bleeder resistors across power supply capacitors
Connect ground to earth across a resistor (2 to 10 ohms 5 watt)
All ways keep 1 hand in your pocket
when measuring and remember you are dealing with high voltages that can
be lethal so if you are not sure dont play with your life and those of other
people who might use you're equiptment so good luck , have fun.

High end sound is the result of a carefull sequence , choice of the proper building materials
Excellent theoretical design where the right balance between simplicity and technology are found
And good lay out of components and nice and clean soldering and mechanical strength .

Most common examples of misunderstanding :
Caddock resistor that feeds a led .
Super expensive cable from the wall socket to the amp ( 1000us$ siltech proposes this and so do others )
Top quality components in middle class designs . ( they will just make it worse )
Fuse between output transformer and speaker

info : email sales@diyparadiso.com