C4S L/R readings variance - should I care?

[arisrock]

Finished the built of the Eros. All measurements were spot-on, except the last two on the C4S board:

Bearing in-mind that the testing instructions advise 10% variance outside the spectrum is acceptable, I measured the following on the OKC and OKD locations on the C4S board:

Expected: OkC 0.7-2V. Observed: 1.6V (Great)
Expected: OkD 0.7-2V. Observed: 2.1V (within 10%).

My question is, 2.1V is 13% higher than 1.6V. Should I do anything about it? Like trying to get matched tubes?

The EROS sounds magnificent btw so I'm not bothered to "fix" anything, but thought I'd best ask since I am a complete novice

[Paul Birkeland]

If everything else is OK, I would run your Eros for 3-4 days straight without turning it off, then recheck those voltages.  I would suspect that they will settle down and tighten up a bit.  We see this a lot with really old tubes that have sat around for decades, they need a little time to settle back down to operate properly.

That particular voltage is dependent on both the EF86 on that side and the 6922, so perfectly matched EF86s will still probably not give a perfectly matched set of cathode voltages unless the sections inside the 6922 are also perfectly balanced. 

[arisrock]

Hi Paul. I left the amp on for a few hours (not days as you recommended), and one channel developed a scratchy hashy complex noise. U unplugged the unit, re-tested all resistances and voltages and read the manual. Voltage for the right channel had drop within tolerances to 1.9V (as you said).

I ended up swapping the EF86 valves around and the very loud complex noise switched channels. I'm assuming one of the valves was fried so I disconnected the Eros and ordered a new pair of Siemens https://www.watfordvalves.com/product_detail.asp?id=813 as that site highly recommends them (this seems to be the place to buy valves in the UK).

Just thought I"d check in to confirm if that sounds like it's a dead valve to be discarded.

thank you in advance!
Aris

[Paul Birkeland]

Can you run the Eros for a few days, not a few hours, to let the tubes settle in?