Bye-bye electrolytics?

[Ptron]

These look interesting. Pretty cost prohibative right now. $26.66 for a 35uF 500v one at Mouser. I wonder if those prices will come down eventually since this is a new product.

[Don Symes]

I dunno - 1.4 x 2.125" (roughly) for 35uF - and there's only one case size, so even the 4u7s are that big - is pretty inconvenient.

Unless you're doing big, high-voltage switch-mode power supplies - or some other application with ridiculous ripple currents, you really don't need these.

Like most new technologies, they're probably priced at a slight premium over whatever you would normally do right now. If they catch on, the prices will come down a ways, but these are for a niche application, so 'lytics will continue to rule the capacity/size/price matrix at our piddly little few hundred mA of ripple current.

Just my opinion, of course - and a nifty find nonetheless.

[R.G.]

They look to be a repackage of the existing AC motor run caps, possibly with some attempt to get higher ripple current.

I've used motor run caps for plate supplies before. They work great, the only ugliness being weight and size. If you shop carefully, you can find the oval motor run caps for about $1/uF in 377Vac (that's 522Vdc) rating for 10-20uF. They usually stock them in HVAC supply centers.

These are the same technology - thin polypropylene film dielectric.

The SCREAMING advantage is that both types will never need replacing like electros will.

[bob p]

These look interesting. Pretty cost prohibative right now. $26.66 for a 35uF 500v one at Mouser. I wonder if those prices will come down eventually since this is a new product.

I've just used CDE-UNL in a project -- a homebrew amp that I had decided that I don't want to ever have to worry about recapping. Depending upon how you look at the cost analysis, these caps might actually be cheaper than electrolytics.

Consider that some forms of electrolytics are expensive. The $/uF keeps climbing on low production volume, special-format caps like Sprague Atoms. Haven't they doubled in cost over the past year? Eventually those caps will need to be replaced, and they'll inevitably cost more in the future, when they're even less popular than they are now.

Its also worthwhile to consider that if a CDE type UNL cap never has to be replaced, you never have to deal with the downtime of an amp, you never have to drag it to a repair shop, and you never have to pay for either parts or labor for recapping.

In many respects, building the "immortal" amplifier can be a very cost-effective approach -- especially if your time is more valuable than the incremental materials cost.

[Enzo]

I like the work I do to be reliable, on the other hand, I am not all that concerned that 30 years from now a cap might need replacing. And who knows what wonderful caps they might have by then?

[R.G.]

... And who knows what wonderful caps they might have by then?

That's what I thought 30 years ago...

[bob p]

Enzo, performing reliable repairs is an important part of an ethical business model. As you probably know, there are bad repair shops out there -- you know, the kind that will replace a cap with one that's under-rated for voltage, just so that the customer has to come back to them for another repair bill. I actually had that happen to me a long, long time ago. But I digress.

I think there's a difference in what's economically cost effective when you're selling a repair job to customers, vs. what's cost effective when you're building something for yourself. At times its hard enough to sell a proper repair (using OEM quality parts that make you comfortable in providing a warranty) to a customer who's pinching pennies and looking for the least expensive way out of the door. It would be harder still to sell this kind of customer an "immortal" repair.

On the other side of the coin, there are customers who do like the idea and are willing to pay for it, though I would agree that its probably not a sustainable business model for anything other than the boutique clientele. Since I don't actually do this sort of thing for a living, I can afford to take an approach that would not be considered cost effective, or a sustainable business model.

My personal bias is that when I'm building something for myself, I prefer to use the best quality parts available. I do this becuase I appreciate build quality that's higher than what is commercially available. I also do this because there are so many demands on my time that it makes more sense for me to spend the extra money up front rather than to return to the amp at a later date. I would miss my time more than I miss the extra money, and if a cap lasts my lifetime, I think its money well spent. Granted, this is probably a viewpoint that's out of the ordinary (I can thank R.G. for enticing me down this path), but its something that works for me.

thanks again for sharing your expertise.