Newsgroup: it.hobby.elettronica.riparazioni
Titolo: Info Resistenza Monitor

Non essendo molto pratico di elettronica, Vi scrivo per avere
da voi delle informazioni su una resistenza di cui ho bisogno.
La resistenza fa parte di un monitor per PC e secondo il manuale
tecnico che sono riuscito a reperire su internet ha queste 
caratteristiche: >>RM-OXIDE FILM 2W 1.2 OHM 5% (TAPPING)<<
Ora vi chiedo:
1) Cosa sta a significare ''OXIDE FILM'' ? E' un particolare tipo di 
resistenza?
2) Cosa sta a significare ''(TAPPING)''?
Ringrazio anticipatamente chi mi rispondera'   
-- 
ddd

 ha scritto nel messaggio
news:200509130...@mynewsgate.net...

  The Best Resistor...?
Choosing the "best" resistor for your audio project need not be an exercise
in anxiety and confusion. I've tried ALL of the various signal types we sell
(as well as many others...) in my own projects, in almost every conceivable
position, and, providing that you select the correct wattage rating and
ohmic value, they all work OK. You can't really make a 'wrong' choice.
Discovering the subtle character of the various signal types in your circuit
should be viewed as an adventure, not a dilemma. The perceived sound quality
differences of the various types in audio circuits is, of course, highly
subjective and personal. Some audio gurus make a big deal about the "best"
type of signal resistor to use in specific positions in a tube circuit but I
don't happen to agree with this authoritarian approach. I've been around
long enough to see many audio parts fads come and go. Remember when the
audio hobbyist and 'high end' rags were touting the "improved sound quality"
of metal films over everything else? Below find my impressions of the
various types of resistors we sell, as well as my opinons of other types
I've tried over the past twenty five years. Note that some types of
resistors are, generally, more appropriate for signal positions, others for
cathode bias or for power supply applications. Still, it's as much fun to
try 'em where they "don't belong" as where they do, just to hear what the
heck they sound like in there. As always, I encourage you to experiment and
reach your own conclusions instead of following somebody else's groove.
In my opinion, generic metal films, commonly available from Mouser,
Digi-Key, Radio Shack, etc. are to be avoided, even for economy conscious
repairs. Sadly, most new mass market guitar amps and audio components are
made with these generic metal films. The bad rap hung on metal films for
being "spikey" and "cold" comes, mainly I think, from the sonic character of
these cheap resistors. Worse, I've seen numerous failures in service,
especially in guitar amps and other gear that gets rough handling.
Military ("Mil. Spec.") metal film resistors, available at government
auction, hamfests, surplus dealers, etc. can offer good sound quality and
excellent reliability for a very cheap price. If you're building on a
restricted budget, these are an OK choice for hi-fi but maybe not for
vintage Fender style guitar amps. On the other hand, some great British
guitar amps were built with British military metal film resitors. Do be
careful of the somewhat cryptic ratings printed on these Mil. Spec. parts;
if you're not sure what you're getting, don't use 'em. Check every resistor
with a meter before you solder 'em in place.
Audiophile metal film resistors, including Resista, Holco, Beyschlag, etc.
really do sound OK for hi-fi. Use 'em where tight value matching, long term
reliability and temperature stability are important. You'll get great
high-end detail, extension and imaging. On the other hand, compared to
carbons, you'll sacrifice some of the warmth many of us love in old vintage
gear. Also be aware of the warnings about bending the leads of Holco
audiophile metal film resistors too close to the body or you may stress the
end cap/lead welds, possibly (some claim...) resulting in noise.
Metal oxide types from Mouser, etc. are best used only in power supplies
when a high wattage rating is required in a small package. I usually avoid
using these resistors in signal positions, since they seem to give a
somewhat 'washed out' and grainy sounding midrange.
Premium non-inductive wirewounds sound excellent in audio circuits but it's
hard to find a supplier stocking a range of values wide enough to build an
entire circuit. If somebody out there knows of a good source for these,
please let me know. Industrial wirewounds by Dale, Ohmite Brown Devil and
others are OK for power supplies and some hobbyists do like these in signal
positions as well.
Metal foil resistors, the "sound of the '80s" High-End", are favored by many
audionuts but, in this elevated price class, I prefer the sound of tants and
Rikens.
Vintage carbon resistors by Allen Bradley, Stackpole, etc. sound very nice
to me but tolerances are poor, as is temperature stability. Accordingly,
it's difficult to get a stereo circuit properly balanced, so imaging will
suffer somewhat, compared to the other signal resistor types we recommend
There's also the issue of noise, not objectionable to my ear in most power
amp circuits but probably too much for a phono stage? Still, these antique
resistors are the most authentic choice for restoration of vintage guitar
amps and hi-fi. More than just for authentic looks, they preserve the
signature sounds of a bygone era. Quality carbon composition resistors will
soon be almost impossible to find in a wide range of values, so get 'em
while you can. We've been told that Allen Bradley has ceased production. My
advice is also to test each and every carbon resistor you intend to use, and
scrape the leads before you solder. Your old local electronics supply or
TV/Radio repair store may have a good stock of carbon resistors on hand,
usually at very cheap prices. Hamfests and government surplus sales are
other good sources.
Riken Ohm carbon film resistors are my personal favorite; the sound
approaches the warmth of vintage carbon types but without the noise and
drift. I'd be happy to use nothing but Rikens if I could get every value and
wattage rated needed for my projects. I love the sound of Rikens in both
hi-fi and guitar amps.
Tants are a real mystery to me. Tantalum capacitors sound terrible in most
audio circuits but tantalum resistors sound fantastic; warmth and detail
abound! We've attempted to obtain more technical information about these
resistors from the manufacturer but our requests are always ignored. The
rumor is that production of the finer grades of tantalum audiophile
resistors has ceased, so my suggestion is to get them while you still can.
My listening experiences with Japanese Audio Note gear led me to try tants
in my own hi-fi projects. If you want to gracefully extract the last bit of
information from an audio circuit, and your budget can stand it, this is a
fun resistor to experiment with.