I was told that metal film resistors should not be used with tubes because
they make the circuit ring. Carbon films sound better.

I see no basis for this in specifications for metal films. Any opinions or
facts? Thanks, Mark

Marko wrote:

I was told that metal film resistors should not be used with tubes because
they make the circuit ring. Carbon films sound better.

I see no basis for this in specifications for metal films. Any opinions or
facts?

Facts? There's no problem using metal film resistors in tube gear. But
you should use 0.5W types, as the 0.25W types often have a low voltage
rating.

If they sound better or worse than carbon films or carbon comps is a
different matter - try all types and see what you like.

I just use what I have. Mostly metal films and sometimes ancient carbon
comps.

Best regards,

Mikkel C. Simonsen

"Marko" asked:

: I was told that metal film resistors should not be used with tubes because
: they make the circuit ring. Carbon films sound better.
:
: I see no basis for this in specifications for metal films. Any opinions or
: facts? Thanks, Mark

What about the jokes???

You know, metal "ringing", carbon "damped" ;=}) Must be a slow day ...

Seriously, the only caveats I've heard of are some voltage limitations
for metal films - but not espcially quantified - perhaps a few hundred
volts? Mikkel's .25W mention is a new one on me too, but logical given
the size. Anybody point to accurate voltage limit specs? (I'm feeling
too tired to go searching all the resistor mfr databases right now:=)

"Experience is something you don't get until just after you need it."
Dave Plowman's everchanging sig. on uk.ra.

"The Greeks had three kinds of columns - Corinthian, Doric, and Ironic."

Ross Matheson wrote:

"Marko" asked:

: I was told that metal film resistors should not be used with tubes because
: they make the circuit ring. Carbon films sound better.
:
: I see no basis for this in specifications for metal films. Any opinions or
: facts? Thanks, Mark

What about the jokes???

You know, metal "ringing", carbon "damped" ;=}) Must be a slow day ...

Seriously, the only caveats I've heard of are some voltage limitations
for metal films - but not espcially quantified - perhaps a few hundred
volts? Mikkel's .25W mention is a new one on me too, but logical given
the size. Anybody point to accurate voltage limit specs?

0.25W resistors often have a 200 or 250V limit. 0.5W resistors generally
have a 350V limit. I don't remember if the 1W or 2W types have higher
voltage ratings, but I guess I could look that up...

Best regards,

Mikkel C. Simonsen

Seriously, the only caveats I've heard of are some voltage limitations
for metal films - but not espcially quantified - perhaps a few hundred
volts? Mikkel's .25W mention is a new one on me too, but logical given
the size.

Voltage rating of the paint that covers the body of the resistor? Well,
just be sure that
it si in the air and not touching something else. Internal arc over?
Could be an issue....

"Marko" wrote in message
...
I was told that metal film resistors should not be used with tubes because
they make the circuit ring. Carbon films sound better.

Hi Mark,

I have seen some concern about inductive and capacitive aspects of certain
types of metal films in certain applications -- even though most specs say
they are 'non-inductive' or don't address the issue. Anecdotally, I have
seen RF transmitters, broadcast exciters, etc. with lots of metal films
throughout, and carbon composition resistors retained in the high-frequency
areas. This may be the source of the 'ringing' comment you mentioned . . .

I do think it is safe to say that the level of extra reactance in modern
metal films is low enough to be extremely unlikely a point of concern in
tube audio electronics -- maybe in a tube VHF transmitter you might worry
about it. It is also safe to say that modern metal films definately have
substantially lower noise and tighter tolerances than carbon composition
resistors (even modern carbon comps), and thus it is very possible for them
to change the sound of the device in question.

As a general rule, I believe in preserving the value of collectable and
valuable historic equipment by using original parts when appropriate, but
for new designs or substantial modifications I feel that the more the
artifacts of the parts are reduced, the closer you will be to hearing the
sound of the circuit itself . . . and hopefully if the circuit is doing its
job, closer to the sound of the music.

I recommend that you heed the advice others have posted regarding voltage
ratings, and enjoy the performance of modern resistors -- if there is indeed
any ringing, it can be measured, analyzed, and dealt with through proper
circuit changes rather than blindly swapping parts.

Best regards,

Kirk Patton

Thank You for all the replies. I am presently wrestling with
airconditioning problems. I will read all of them when I get to it. Thanks
load guys, Mark (top post)
"Kirk Patton" wrote in message
y.com...

"Marko" wrote in message
...
I was told that metal film resistors should not be used with tubes
because
they make the circuit ring. Carbon films sound better.

Hi Mark,

I have seen some concern about inductive and capacitive aspects of certain
types of metal films in certain applications -- even though most specs say
they are 'non-inductive' or don't address the issue. Anecdotally, I have
seen RF transmitters, broadcast exciters, etc. with lots of metal films
throughout, and carbon composition resistors retained in the
high-frequency
areas. This may be the source of the 'ringing' comment you mentioned . .
..

I do think it is safe to say that the level of extra reactance in modern
metal films is low enough to be extremely unlikely a point of concern in
tube audio electronics -- maybe in a tube VHF transmitter you might worry
about it. It is also safe to say that modern metal films definately have
substantially lower noise and tighter tolerances than carbon composition
resistors (even modern carbon comps), and thus it is very possible for
them
to change the sound of the device in question.

As a general rule, I believe in preserving the value of collectable and
valuable historic equipment by using original parts when appropriate, but
for new designs or substantial modifications I feel that the more the
artifacts of the parts are reduced, the closer you will be to hearing the
sound of the circuit itself . . . and hopefully if the circuit is doing
its
job, closer to the sound of the music.

I recommend that you heed the advice others have posted regarding voltage
ratings, and enjoy the performance of modern resistors -- if there is
indeed
any ringing, it can be measured, analyzed, and dealt with through proper
circuit changes rather than blindly swapping parts.

Best regards,

Kirk Patton

"Kirk Patton" wrote in message
y.com...

"Marko" wrote in message
...
I was told that metal film resistors should not be used with tubes
because
they make the circuit ring. Carbon films sound better.

Hi Mark,

I have seen some concern about inductive and capacitive aspects of certain
types of metal films in certain applications -- even though most specs say
they are 'non-inductive' or don't address the issue. Anecdotally, I have
seen RF transmitters, broadcast exciters, etc. with lots of metal films
throughout, and carbon composition resistors retained in the
high-frequency
areas. This may be the source of the 'ringing' comment you mentioned . .
..

I don't know that metal films do have a tonal effect. I was only told this.
The advice I received was that metal films tended to cause supersonic
oscillations. I know that actual inductance of metal films is no more than
carbon, they are both spiralled similarly. I thought mabey it had to do
with some sort of molecular peculiarity, possibly due to some strange
circular patterns the electrons may take within the path through the
resistor element. Sort of like little molecular eddy currents. I rebuilt
my first tube amp, a Heath W-2 with metal films. I don't like the sound of
it. I used Arco paper/mylar caps which have the classic paper sounds so I
know the caps aren't the problem. I think the audiophile rage about
polypropylene is unfounded. The hard dielectrics seem to have a hard sound.
Paper is flexible. I say this because I have some teflon caps which sound
like paper. Teflon is very flexible and has a sound similar to a Vitamin-Q.
Teflon's are rare special order components for hi-temp. If they ever catch
on audio may improve in general.

I do think it is safe to say that the level of extra reactance in modern
metal films is low enough to be extremely unlikely a point of concern in
tube audio electronics -- maybe in a tube VHF transmitter you might worry
about it. It is also safe to say that modern metal films definately have
substantially lower noise and tighter tolerances than carbon composition
resistors (even modern carbon comps), and thus it is very possible for
them
to change the sound of the device in question.

Definately, there is much lower noise, in metal film. thick film resistors
which are not sputtered but painted have noise comparable to carbon, as do
metal oxide.

As a general rule, I believe in preserving the value of collectable and
valuable historic equipment by using original parts when appropriate, but
for new designs or substantial modifications I feel that the more the
artifacts of the parts are reduced, the closer you will be to hearing the
sound of the circuit itself . . . and hopefully if the circuit is doing
its
job, closer to the sound of the music.

Agreed, but although I have a massive assortment of NOS carbon comps, easily
100,000 of all values and all wattages, they are basically unuseable because
they have gone out of tolerance as much as 30%. A design engineer from the
60s said they had to "bake" their design assortments of comps every couple
years to bring them back into tolerance.

I recommend that you heed the advice others have posted regarding voltage
ratings, and enjoy the performance of modern resistors -- if there is
indeed
any ringing, it can be measured, analyzed, and dealt with through proper
circuit changes rather than blindly swapping parts.

I doubt that they will ring, but I thought I would check with you guys
first. I would be using RN70D metal films for the most part so the voltage
rating wouldn't be a critical factor. Good point though. I also have a lot
of old NOS Dale and T.I. military carbons which I suspect will have a much
better sound than the metal films. Just a strong hunch. Thanks for the
interesting reply, Mark

Best regards,

Kirk Patton

Good quality metal films should be stable and distort hardly at all.
Poor quality metal films can be noisy and distort due to
manufacturing defects (eg local heating effects due to thinner parts
of film, and poor lead attachment). I guess the same goes for
carbon, but sometimes I think folk compare good carbon with poor mf
and come to false generalisations.

I suspect that some folk like carbon for the same reason they like
paper and oil caps...harmonic distortion. I don't know what the
mechanism for that is...possibly poor heat conduction and
temperature coefficient on the part of carbon?

It would be interesting to compare typical capacitance and
inductance for the two types. If ringing occurs with one type and
not the other, these would be the parameters to compare I suppose.

I have read lots of times that mf gives a relatively "hard" sound.
I take it that means low distortion rather than high odd harmonics.

cheers, Ian

"Marko" wrote in message
...
I was told that metal film resistors should not be used with tubes
because
they make the circuit ring. Carbon films sound better.

I see no basis for this in specifications for metal films. Any
opinions or
facts? Thanks, Mark

I experimented with resistors a while back, by accident. I was fixing
an old tube radio, and replaced the feedback resistor with a metal
film. I could hear a difference, and it wasn't good. I went into a
long testing session, and found the carbon comps sounded the best,
followed by ratshack carbon films (the only films I had). All other
metal, and oxide resistors either tended to have a edgy (metallic?)
sound or imparted a strange flatness (mostly the metal oxides) to the
sound. Only the carbons imparted a smooth, deep sound to the radio.
Needless to say, I've since stocked quite a large amount of carbon
comp resistors.

I don't know how wirewound resistors would stack up, but I imagine
they should be neutral, if anything.


Bob Hedberg.

"Marko" wrote:

I was told that metal film resistors should not be used with tubes because
they make the circuit ring. Carbon films sound better.

I see no basis for this in specifications for metal films. Any opinions or
facts? Thanks, Mark


Bob H.

Just grab that plate in one hand, the chassis in the other,
and FEEL the power of tube audio!!!
(not literally, of course, just kidding. DON'T DO THAT!)