Audio Research Reference 250 capacitor issue

My understanding from digging was that the white caps were great but that there were problems with some of those caps early on in production. Not to worry, ARC tests the caps to make sure they are free from defects before install and the defective ones were returned to the manufacturer. I was also told that if the caps passed the initial testing and were installed, they were good for as long as any other caps.
ARC was hoping for the longest time that the manufacturer could continue and/or increase production--indeed, ARC's wait for these caps was the main reason for the long delays in upgrading the Ref 5 and the Ref Phono 2 to SE which included an upgrade of the caps.
In the end, the manufacturer either could not come through with enough product in time, ceased production or went under so ARC looked elsewhere for caps. Hence the gold caps. If you have white caps, rest easy

I think you will find that the "New" coupling capacitors are in fact an Film n Foil job as a-posed to the previously employed teflon's.

If you look carefully under the hood on older production units you will also notice that ARC utilised a smaller Teflon bypass capacitor in parallel with the main coupling capacitors, the later units sporting the Gold FnF no longer require this bypass cap as presumably these are wider bandwidth capable.

Personally, I would not be best pleased were ARC to Ship my unit back, post service, sporting a mix of older Teflon's and FnF's.

I think the old Teflon capacitors are not able to handle high voltages and arc replaced them with new gold color capacitors. They are continuing using Teflon capacitors in preamps but discontinued in amplifiers. I have 30 hrs on my capacitors and they sound pretty good. Don't hear any difference. After 100hrs of breakin they should sound better.

Here's an excerpt from some Qs and As between Kal and me re the Teflon caps. Kal's responses are in quotes.

Thanks Kal and welcome back. Gotta a couple of follow up Qs re white Teflon caps.

1. If the teflons are working, do they sound as good as the replacement gold caps? "YES"

2. How would I know if the white teflons are NOT working. Would there be some sound degradation or would it be like an “on and off switch” … the teflons work … or they do not work?? IOW, If defective, would I ... lose a channel. "You would not be able to bias the output tubes."

That's it. Just checked the bias on my Ref 150's KT-120s. All seems ok, so far.

*****

Btw, anyone experience similar issues with the Teflon caps in the Ref 5 SE or Ref Phono 2 SE??

The teflon caps in my Ref 40, Ref 150 and Ref Phono 2SE have not only had no problems, but to my ears are one of the main reasons that the sound of this generation of ARC gear is so much better than the last. I'm not giving mine up.