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Eico HF-35 and Knight KB-85 mods

Posted by Nebulix (A) on July 14, 2013 at 22:18:36

In Reply to: RE: Eico HF-35 and Knight KB-85 mods posted by Eli Duttman on July 14, 2013 at 21:40:49:

Thank you Eli. I'll try that tomorrow. Sounds simple enough.

Now I've been searching through the forum about PIO threads.

If anyone knows the Eico HF-35 (or any of the similar HF-series) there are two coupling capacitors C5 and C7, to the final stage. The original spec was 0.1 uF @ 600V. I've replaced them with modern film capacitors but would like to go with Russian PIOs. For some reason, the HF-35 specifies 0.1 uF, but other models such as the HF-60 use 0.25 uF for coupling. Is this a preferable value e.g. more bass? More? (The PIOs are 0.22 uF, but I see one guy put 1.0 uF in this place.)

Also, there's a capacitor C4, grounded from the grid of the phase inverter. The original was a molded 0.25 uF @ 400V. I've replaced it also with a film cap. I see that Stu replaces this one with a PIO. Is this capacitor actually considered to be in the signal path i.e. is it worth me replacing it with a PIO?

Thanks in advance,
Duncan Mc.

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