Iskras 0.5w vs 0.25w

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demonufo
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Re: Iskras 0.5w vs 0.25w

Post by demonufo » Mon Jul 25, 2011 4:26 am

Hmm, perhaps my CC stash is of later manufacture than I thought then. It's difficult to put a date on what I have though, as I don't have the packaging like I do with my Pihers. All I know is a rough timeline as to when the workshop assembled the batch of resistors that I liberated from my former employers! :twisted:
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Re: Iskras 0.5w vs 0.25w

Post by wrea398 » Thu Jul 28, 2011 7:22 pm

Here is a pic of 1/2 watt, 1 watt and 2 watt Pihers. The 1 watters are 10k, the 2 watt are 56K. The 2 watt are WAY larger than any pics I have seen of an actual amp. The 1 watt are the correct resitors in 10K and 8.2K positions and the 2W dont fit on the board. The (2) 56K 2 watters are correct fo the F2 and F3 can caps on '69-73 year models.
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Re: Iskras 0.5w vs 0.25w

Post by jnew » Tue Dec 15, 2015 10:36 am

I've always wondered about the 2W thing in the power section. I always see 1W resistors there. :what:
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Re: Iskras 0.5w vs 0.25w

Post by Xplorer » Tue Dec 15, 2015 11:20 am

Hi, wrea ? would you perhaps have a spare 56k 2w piher ? ;)
i have one, just missing one for an SL build. But if you don't, nevermind i'll find a solution soon or later. thanks
wrea398 wrote:Here is a pic of 1/2 watt, 1 watt and 2 watt Pihers. The 1 watters are 10k, the 2 watt are 56K. The 2 watt are WAY larger than any pics I have seen of an actual amp. The 1 watt are the correct resitors in 10K and 8.2K positions and the 2W dont fit on the board. The (2) 56K 2 watters are correct fo the F2 and F3 can caps on '69-73 year models.

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Re: Iskras 0.5w vs 0.25w

Post by Haze13 » Thu Dec 17, 2015 2:18 am

Jnew, if you ask why to use 2W resistors in power sections, is because of the noise that is generated when there is a voltage across that resistor and a drift of the value of that resistors when he heats up. Some new metal oxide resistors are very stable when they heat up, and there is no need to worry about their drift. It's important when you need stable screen voltage on the power tubes, and quiet preamp with a high gain.
BUT, when you need Vintage sound, forget about what I said :)

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