If you can justify the price and resistances are <100K, the Vishay/Texas Components TX2575/Charcroft CAR Z-foil equivalents are the most transparent, surpassing MK-132. If cost is a factor, consider Welwyn-- very sweet and clean. I recently used them in Pass amp camp kit monoblocks. No regrets.
Charcroft/ClarityCap OEM Sales
Thanks. Is there an online retailer for the Charcroft CAR resistors?
Hifi collective, UK based, nice to deal with them.
If money is no object then bulk foil are pretty unbeatable - however are probably not worth the expense across the board. The greatest benefit is the low temperature coefficient so worth it when they'll be dissipating some heat or near another component that will.
I use vishay thin film 0.1% as standard, they come in the e192 values so no problem with values up to 1MΩ and easy to find with 10-25ppm tempco.
If you're not already planning to do so then you might want to consider using multiple, parallel op amps in the input stage and going for the lowest resistor values you can get away with in the attenuator. I'm currently using a 500Ω attenuator which will contribute around -128dBv noise... compared to a 10kΩ attenuator which would come out at around -115dBv.
@pragmasi - Thanks for your response. I agree the Vishay thin films sound great. I am going to try to use these in as many places in the signal path I can.
I am using the Salas DCG3 circuit for the output stage (in a balanced configuration) and this works best with a source impedance of 5K, so that is what I selected for my attenuator. But I am running fully balanced (two attenuator banks per channel), so this will help with the resistor noise.
@petg60 - Thanks for the suggestion of Hifi Collective as a retailer.
@jaytor Did you see partsconnexion has a sale on Audio Note Tantalum resistors? I haven't heard them, but I see a lot of manufacturers advertising their use.
I haven't done good listening tests, but I chose naked z foil throughout the signal path of my amplifiers, vishay/mills non-magnetic wirewound in the high dissipation locations, and good ol vishay/dale RNs everywhere else. Not that any of those are news to you...
I'd hoped to compare a standard (First Watt F4) amplifier build to one with all those top parts, but also got talked into using different mosfets by Nelson Pass. Unfortunately that made it so that there are too many differences to really pin down what makes the new boards superior. They are way better though.
@cal3713 the Audionote Tantalum resistors that are on sale are the magnetic variety. I've seen a few posts from people when I was researching resistors who tried those and were not happy. I think the non magnetic versions are supposed to be much better. Probably why they are phasing out the magnetic versions.
I've ordered a combination of Vishay and Charcroft z-foils for all the signal path resistors and Takman REY resistors for the rest. Based on my experience with my current preamp, I'm sure I'll be satisfied with these.
I think it's worth pointing out that tantalum is a conflict mineral, something I didn't realise until a few years ago which led me to stop using the capacitors.
@pragmasi - Good to know. Thanks for pointing that out. I wasn't aware of that.
You can see the components I build on my system page.
From my eperience:
Amtrans are very nice
Caddock - OK not my preference although used to be at one time
Riken good for the money
Takman good carbon is musical
Takman - not a fan of metal resistors
Vishay resolution but not as much in musicality
Shinkoh if you are looking for emotion this is the resistor to use
Audio Note - yes
Audio Note Silver big yes
Swap of the top resistors on your
Khozmo with a pair of the AN silver resistors as a first step
@bigkidz - thanks for your feedback. That's helpful.
I wonder if you can comment on what kind of differences you hear with different resistors?
I haven't done direct A/B comparisons of different resistors in the same circuit, but I have noticed that circuits built with different resistor types tend to sound different. Specifically, the Z-foil resistors add a lot of clarity and detail (removing a veil as some describe it), but they don't sound as warm and rich as some other resistors.
Cheap carbon resistors tend to sound a bit dull with less detail. Better carbon film resistors add some warmth and richness.
These differences are fairly subtle and I doubt very much I'd be able to tell the difference replacing a single resistor (although others have claimed otherwise), but building an entire preamp using higher quality resistors definitely improves the sound.
As an example, check out the reviews of the Wyred 4 Sound STP-SE base model and with upgrades. The with Stage 2 upgrades. One of the key differences with the upgrades is replacing most of the signal path resistors with Z-foils.
Several months ago, I completed a DIY preamp where I used Vishay Z-foil resistors (Takman REX shunt resistors in the attenuator) for all signal path resistors. This preamp turned out to have significantly improved detail over the Parasound JC-2 preamp I had been using. It's not often that I have replaced a single component and heard such stark differences. Obviously there were other differences in the circuits, connectors, wiring, etc., but I believe the higher quality resistors had a lot to do with the sound quality improvements.
And I figured out a way to make 5 cent resistors sound like the cheapest non magnetic 1/4 and 1/2 watt resistors. for like 0.3 cents per resistor.
I think that is a bigger deal, as the people we want to reach are those who don't believe that any of this makes a difference.
And the only way to train their hearing, is to get better gear in their hands and let them listen and learn, over time.
Where they will only do this at a price they can accept, which is the gear with the crappiest 5 cent resistors. The end.