Audio Research Reference 250 capacitor issue

I was looking at buying an used Ref 150. I got the serial number from the seller and asked ARC tech when it was manufactured. It was in 2011.

I then asked if there is any difference in terms of innards - components used - in the 2013/2014 Ref 150 versus one manufactured back in 2011. He told me the earlier ones has white Teflon caps, but due to 'no more supply' of those caps, ARC switched to the gold color Teflon caps.

I then asked him if there is any quality (sound quality) difference, and he said "you probably won't hear any difference".

There was no mention of any reliability aspect of that white cap versus the new gold cap.

this mix of white and gold cap got me thinking ...

You were offered the whole kit - which consists of all the caps, for what reason?

Because ARC feels its an 'upgrade' (i.e, better parts, better sound)?

Or because ARC doesn't have the old white cap in stock any longer, and because you cannot have a mix of them in your amp, therefore you had to buy the whole kit and replace all the caps? But then, one of you mentioned that your Ref 250 contains a mix of white and gold foil Teflon caps. So what's the deal then?

If you have one of the more recently manufactured amp with the gold foil Teflon cap, and one cap goes back, does it mean that you only need to buy/pay one cap as replacement?

I am going to call Kalvin at ARC and ask him these questions tomorrow.

Been passing messages with Kal. I asked some follow up Qs that pose the same Qs as posed above. I'll report back.

Btw, Kal mentioned that the G Series should hit the stores soon. He sent me a spec sheet on G Serie gear. The G-150 has almost identical specs to the Ref 150, e.g., wpc, power supply, etc. The wpc spec was a little higher than the Ref 150, but I attribute that to the KT-150 tube.

Kal said the KT-150 are still not approved for the current Ref line. I think this is about marketing.

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.