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guypettigrew

Elna Silmic II capacitors

12 posts in this topic

On Friday evening one channel suddenly dropped in volume and lost it's top end. This was followed by a nasty burning smell from one of the 300B PSE monoblocks. I turned everything off and went to bed!

When I tried the amp again on Saturday I noticed one of the 300B valves was getting really hot. A bit of poking around with a test meter and a shorted cap was soon identified. It was a 100v 100uF Black Gate cathode bypass cap.

Black Gates aren't available any more, so I've ordered a quartet of the Elna Silmic IIs to replace all the Black Gates. Should arrive tomorrow.

Has anyone used these? Do you have any views on them? Do they need to burn in like the Black Gates, which always needed a fair bit of running in before they "popped" and start sounding right.

Thanks.

Guy
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Not really a like for like swap. You'd be better off with something like a Panasonic NHG or MUSE KZ would be closer in terms of intended use and measurements. Silmics are best used in the signal path.
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100V rating for the cathode bypass cap on a 300B seems low to me. Especially given that the bias voltage must be somewhere between 65 and 80v. Normal rule of thumb there is to double it & I think I've always used 250v caps in that application.

I like the Cerafines for bypass use.
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Cerafines and KZ can both be had from hificollective
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[quote name='murray johnson']100V rating for the cathode bypass cap on a 300B seems low to me. Especially given that the bias voltage must be somewhere between 65 and 80v. Normal rule of thumb there is to double it & I think I've always used 250v caps in that application.

I like the Cerafines for bypass use.[/QUOTE]

According to the circuit diagram they're only at 38v, so 100v should be OK, hopefully?

Thanks for the info on HiFi Collective. I'll have a look.

Guy
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[quote name='guypettigrew']According to the circuit diagram they're only at 38v, so 100v should be OK, hopefully?

Thanks for the info on HiFi Collective. I'll have a look.

Guy[/QUOTE]

They'll be fine, yes.
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Silmics can sound a bit dull in certain positions, but they may change a bit with a bit of run-in though. Popular caps are Panasonic FM or FC and Rubycon ZLG and ZL. The Panasonic NHG are supposed to be a good all-rounder so may be worth a try.
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Silmics are nice in analogue power supply (including DAC analogue decoupling) & some report great sound as feedback caps, but don't like any 'lyrics in the signal path & wouldn't use these in cathode bypass.

To be honest it doesn't get better than Black Gate caps for cathode bypass unless you start moving to film caps, and at 100uf this is simply not practical from size and price perspectives. Elna Cerafine are the most comparable caps in terms of sound. I'd just get some replacement Black Gates. Michael Percy [url]http://www.percyaudio.com/Catalog.pdf[/url] seems to be stocking 100uf Black Gate FKs (a definite upgrade if you've just replaced standard BGs):

100µF . . . . . . . .100V . . . . .15.50USD ..........18mm x 35mm

And standard BGs

100µF . . . . . . . .100V . . . . . .4.75USD ..........16mm x 25mm

Yeah £37 for a few caps seems high, but you've already discovered the impact that cathode bypass caps have on sound! Either way stick to the Black Gates IMO & at $4.75 each the STD caps are a no-brainer.
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You can fanny about for ages, or you can just buy some Panasonic NHG like I suggested. Trust me on this.
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