Metal or Carbon Resistors - Which is better?

I suppose it would also matter which specific brands were offered too.  A local builder of very high end custom electronics likes certain vintage carbon composition resistors for the rich and warm sound he favors.  Most of his builds use the likes of vintage Allen Bradleys, for higher builds it might mean vintage IRC resistors, and so very special builds employ Western Electric parts.  

I'd choose metal film in places like power supplies, more likely to choose carbon in signal path. For most mods I've been using Takman carbon film and/or Texas Components TX 2575 naked bulk metal foils, Takman combo of warmer voicing and precision, TX highest resolving/transparent resistor out there, very neutral, some may hear it as analytical. All these resistors have their place, have to weigh out the recipe.

The one with the better implementation. Implementation matters of material rype

@larryi @sns 

You’re both spot on and get my dilemma. No matter what I choose, it’s going to be a bit of tradeoff, resolution and precision vs. romance and presence. 

Sometimes the right choice isn’t about specs, it’s about what makes the music feel right. 

Always tradeoffs, but per the recommendation of an audio buddy I went with the Takman REY metal film in my Hagerman Bugle 3 phono stage.  No regrets, and will likely use them again when I build the Hagerman Cornet 3. . 

I wanted to share my resistor preferences for different applications.

I prefer using tantalum resistors in signal paths and cathodes.

For power supplies, I opt for metal film resistors.

Lastly, for loads, stoppers, and speaker crossovers, I find carbon resistors to be most suitable.

Not sure about "better" but I chose Amtrans AMRG non-magnetic carbon film resistors in my Hattor passive that I use to adjust volume and provide a display and remote control in my system.  I have been happy with the sound, and compared to the many other preamps I have owned I don't believe it leaves anything on the table wrt volume control without gain.

What resistor sounds best very much depends on application.  After several decades of comparing resistors, I have strong opinions on the subject.  A short summary:

For loads (input, interstage and output), Audio Note 2w silver tantalums.  The 2w silver sounds better than 1w or 1/2w.

For gridstoppers, Riken carbon film (discontinued).

For phono RIAA eq, Vishay bulk foil.

For plate loads and power supplies, Mills wirewound.

I don’t like some of the other resistor types mentioned above such as AMRG and Takman, and I haven’t had any luck with vintage Allen Bradley’s.  However, there is one other type that is a solid second or third choice to my favorites listed above, namely, Dale/Vishay CMF metal foils.  The Dales are cheap and readily available in lots of values.  They have a warm, musical sound with good detail and dynamics.  Take a look inside a Lamm preamp or amp and you will see Dale CMFs throughout.  Same with older Cary amps and preamps.

@lalitk 

Supposedly the film resistors are better, but I doubt I’d hear the difference in a passive preamp. If it’s an option, I would try wire resistors, but then again, with the preamp being passive.  I’m not picking on passive preamps, but they so many fewer parts, a few better resistors might only make a difference on paper.

All the best and let us know what you decide.

@lalitk 

Supposedly the film resistors are better, but I doubt I’d hear the difference in a passive preamp. If it’s an option, I would try wire resistors, but then again, with the preamp being passive.  I’m not picking on passive preamps, but they so many fewer parts, a few better resistors might only make a difference on paper.

All the best and let us know what you decide.

For some passive linestages, the resistors are almost the whole game—they have a few switches/selector, and attenuation means a stepped attenuator or relay switching of different combination of resistors.  The right choice is important.

There is a website that reviewed resistors for a passive attenuator and it concluded the Audio Note 2w silver tantalums were the best sounding by far; unfortunately they are so expensive it isn’t practical to use them for all steps in a stepped attenuator.  

@lalitk please let us know the specific use. It is to load a stepped attenuator? Khozmo attenuator? Shunt style stepped attenuator? Omron relay based Shunt type? Thanks.

Nude Vishay ZFoils are wonderfully resolving, quiet and still pleasing to the ears. They do less editorializing than the other resistors mentioned. You could place Audio Note 2W silver tants in the shunt position.  

Potentially even better is to avoid this question by using the Tortuga LDR based “The ePot.V4”system. Perhaps the best sounding attenuator/control center on the market.  I am just not exactly sure what you are up to.  

The review I mentioned is at:
sw1xad.co.uk

If the link doesn’t work, just google “audio note silver tantalum resistor reviews”

Another option is to use an Intact Audio autoformer.  That is the best sounding attenuator I have tried.  

Transformer/autoformer attenuators do a better job of preserving dynamics and sounding vivid than other types.  Instead of burning off the signal in a resistor, transformers reduce voltage by converting it to increased current.  Because of complexity, transformer volume controls have a limited number of secondary windings, and hence, limited number of volume steps.  Autoformers can offer more steps, and some also offer convenience of remote control and balance adjustment.  A good example, is the one made by Emia.

EMIA attenuators use the same autoformers as Intact Audio.  The EMIA products just put the autoformers in a nice looking box with remote control.  Intact Audio sells the raw autoformers for the DIY market.  Moreover, the autoformers all sound the same regardless of the number of steps.  Well, with one big exception—-there are both copper and silver models.  All of the copper models sound the same; all of the silver models sound the same.

I have the 47-step model and there is a small 1.25db difference between each step.  In my system that easily spans the range I need for my various sources.

“For some passive linestages, the resistors are almost the whole game—they have a few switches/selector, and attenuation means a stepped attenuator or relay switching of different combination of resistors.  The right choice is important.”

+1, @larryi 
Exactly. I am trying to see if I can keep the signal (from TT) with minimal coloration. This is my 2nd attempt to access and possibly keep a 300B amps in my system. First attempt was a complete disappointment disaster (please don’t ask about the amp manufacturer). The plan is to audition few well designed 300B amps before settling on the ‘one’ that highlights the true virtues of 300B valve known for! 

The passive pre under consideration is a simple circuit, zero flash, all substance. How good it sounds, only time will tell.  

Here’s what I know about passive pre design, a passive volume and balance control using a 23-step rotary attenuator. The signal path passes through only two fixed resistors at any volume setting, minimizing degradation. Gold-point, double-contact rotary switches (the kind used in industrial test gear) are used for both volume and the 3-position input selector. 
 

@grannyring  - PM sent! 

I know you are trying to minimize coloration by utilizing a passive linestage, but, ultimately, the goal is to achieve the best sound by assembling good and compatible components.  The challenge with passive linestages is a loss of dynamics—the sound tends to be less lively than that of good active linestages.  To me, this would be particularly of concern with 300B amps which also tend toward the polite and undynamic side as compared to 2a3 and 45 tube amps.  
 

I would not narrow the field to any particular design or approach.  While I’ve heard some good passive systems, in most cases, I’ve preferred a good tube active in direct comparison even when the system was theoretically passive compatible.  The active system tends to be more dynamic, harmonically rich and saturated and more engaging—are some of these qualities ‘colorations”?  Perhaps, but who cares?

@larryi 

Appreciate the thoughtful take and advice. I wouldn’t be here if I didn’t keep an open mind :-) 

Metal better for audio applications. Look it up. 

I too would be wary of using a passive pre with 300B. As for 300B lack of dynamics, depends on power supply and speakers used with, I have absolutely no issues with my monoblocks, each has equivalent power supply to what I see in many stereo 300B. And I've directly compared my 300B amps to my 845 SET from Coincident and Art Audio. 

As for the pre, Coincident Statement pre DHT with dual TVS  I'm running with all factory upgrades and some of my own provides all the transparency, dynamics, voicing, presentation I could ask for. This more sympatico combo than a Pass XP22 I previously owned. Latest Coincident pre runs 300B's vs the 101D's mine runs. Vinnie Rossi also has a very nice 300B I considered. DHT pre's are excellent matches for SET amps.

Most vintage gear used carbon film, as they were much cheaper over metal film. Then there are carbon comp resistors that are garbage. We're talking about 1/4 and 1/2w that are the majority in all our gear. The 5w and 10w ceramic resistors are a different story.

Almost all new stuff uses metal film as they are basically the same price as carbon now.

carbon film have much more noise over metal, but are a little more warm sounding. In the signal path, metal should be used, most important in high gain, as in a Phono-pre. In the power supply, and other places, carbon are fine to use. Anytime i replace a resistor, it is with metal film. 

Are there even better ones? Of course. But they can get stupid expensive. They really only make since in things like crossovers.

All of those recommended other than Metal or Carbon resistors, appreciate your input. Unfortunately, manufacturer only offers metal or carbon resistor option. I am keeping my options open but all bets are off if I stumble across a Shindo Monbrison or Masseto from the Ken Shindo era. There’s just something undeniably special about Ken’s designs…the harmonic richness, the pacing, the soul.

A 300B amplifier can sound dynamic if it has a properly designed driver circuit.

The 300B tube is much more difficult to drive than 2a3, 45 and px25. It needs more voltage amplitude and current. The interstage transformer or direct coupling cathode follower driver (Ralph's suggested it) is a must. And in case an interstage transformer needs a powerful driver not like 6sn7.I have a DIY 300B amplifier. In the beginning it had a 6f6 driver in triode mode with RC coupling. Then I changed RC to an interstage transformer Hashimoto A-305. The improvement in dynamics, bass and resolution was huge. Like a completely different amplifier. Then I changed the 6f6 driver tube for a more powerful 6v6 and then for an even more powerful 5881 (6L6). Each time a more powerful driver made the sound bigger, more dynamic and improved instrument separation on more complex music.

Alex, 

You raised good points about 300B driver stage design.  Unfortunately, many utilize 12AX7 drivers and no interstage transformers.  Hence, it remains the case that many 300B amps are a bit polite, dynamically speaking, but 300B amps are favored because of their glorious midrange.  

A 300B amplifier can sound dynamic if it has a properly designed driver circuit. The 300B tube is much more difficult to drive than 2a3, 45 and px25.
@alexberger 

Agreed with your assessment. A 300B amp can sound very dynamic, but it all comes down to the driver circuit design (that’s where my last amp failed to deliver despite of more than one revision). The 300B requires significantly more drive than 2A3, 45, or even PX25, and if the circuit can’t deliver sufficient voltage swing with low distortion, the amp can end up sounding soft, distorted or underwhelming. 

A well-designed driver stage especially one with strong current delivery and proper impedance matching makes a world of difference. I’ve heard 300B amps with properly executed driver circuits that were anything but polite…fast, vivid, and emotionally gripping.

I wonder if anyone heard this amp, 

https://fezzaudio.com/en/produkt/fezz-mira-ceti-300b-evolution/

When Steve McCormack helped me remove the volume control from the signal path in my SMc Audio preamp, I ended up choosing Audio Note 2W Silver Non-Magnetic Tantalum Film resistors to install in place of the stepped attenuator.  Sounds great, no regrets.