Duroch Capacitors


Primaluna amplifiers and preamplifiers use DuRoch capacitors. Who makes them? What's their quality? I haven't been able to find anything online about this brand.

yukio

AI says:

You're right to point out that there isn't much information about "DuRoch capacitors" outside of PrimaLuna's own marketing and product descriptions. This strongly supports the idea that DuRoch isn't a widely available, off-the-shelf brand, but rather a custom-made component for PrimaLuna.

Here's why this is likely the case and why you won't find other mentions:

  • "Made to our specifications": PrimaLuna explicitly states that these are "Premium tinfoil capacitors made to our specifications." This is a key phrase. It means they've contracted with a capacitor manufacturer to produce these specific capacitors based on their unique design requirements (material, size, capacitance, voltage, sonic characteristics, etc.).

     

  • Proprietary Branding: They likely brand these custom capacitors "DuRoch" for their own products to emphasize the bespoke nature of their components and differentiate them. It's a way for PrimaLuna to highlight their attention to detail and sound quality.

  • Supplier Secrecy: The actual manufacturer of these capacitors is almost certainly under a non-disclosure agreement with PrimaLuna. This is common practice in many industries, especially for custom-designed components, to protect trade secrets and intellectual property. The manufacturer wouldn't be allowed to sell "DuRoch" capacitors to anyone else or even disclose that they produce them for PrimaLuna.

  • Focus on Performance, Not Origin: PrimaLuna's marketing focuses on the performance and quality of the DuRoch capacitors ("very expensive but the sonic results speak for themselves"), rather than the identity of the factory that produces them. For their customers, the "who" is less important than the "what it does."

In essence, "DuRoch" is a PrimaLuna-specific designation for a high-quality, custom-engineered tinfoil capacitor, not a publicly traded capacitor manufacturer. You'll continue to find mentions of them exclusively in relation to PrimaLuna's products.

Duroch are metalized film capacitors - metalized aluminum film. They are ok but far from great. 

PL used to use SCR caps (also metalized film) from France but switched to Duroch. The Jupiter copper foil caps are a ton better. Much more organic sounding. Much better imaging; less smear. 

If you want to change the caps the first one to change are the 0.1uf film caps filtering the voltage to the input tubes. 

If you are interesting in modding or switching caps a good trial to do is to get low uF Audyn TrueCopper (0.1 or so) and bypass the output caps.  Make sure to get the right V rating equal to or exceeding the existing (especially important in tubes).   See if you hear a major difference.  If so, you may want to go all copper foil but they are often very physically large. 

"made to our specifications" could easily mean "they wrote our name on their usual caps for us." 

they could be anything, not likely custom made. im curious. id like someome to find out exactly what they really are. 

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Besides the Nichicon 22mf 450v electrolytics, which of the DuRoch capacitors pictured would you immediately change for better sound quality?

 

https://www.primaluna-usa.com/dialogue-premium-preamplifier

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@yukio 

It looks like Prima Luna likes to private-label some of their components: Duroch caps, Prima Luna-branded tubes, etc.

As has been pointed out already, those caps are probably just rebranded by a legit manufacturer, in the same way the generic-brand cat food at the supermarket is made by the same agro conglomerate that makes national brands. If there is evidence regarding the quality of those caps that makes their immediate replacement a must, it hasn’t been shared in this thread.

Also, in typical audiophile fashion, capacitors are the object of endless hand-wringing while the mediocre, entry-level Alps volume control goes completely, totally and utterly unnoticed. If anything in that unit needs replaced immediately, the volume control is it.

I read the page you linked. Kudos to Prima Luna for delving into and showing high-res pics of the circuitry, but the puffery is so brazen that they actually hype their budget pots! 😂😂🤣

Alps has made great pots, but the Blue Velvet ($15 sans motor) isn’t one of them. Prima Luna are correct in pointing out that the Blue Velvet beats a crappy encoder and a $2 digital chip, but that’s faint praise.