218.189.230.55
It all started when we began replacing 'lytics with film caps - he just kept climbing the wall higher and higher. I guess the last straw was when we changed the EF86 47uf 'lytic for a 4.7uf oil cap; Segundo parked himself himself on a ceiling tile and won't budge. And the other guys in the BV Club are waaay outside the speakers.
Maybe it's a good thing that Blackgate stopped making caps. Isn't there a saying, necessity is the predecessor of progress? Whatever, we are driven to use film caps. Of course we can't have the big farad/little can convenience of 'lytics so the power supply needs to be designed differently, choke-centric instead of cap-centric, more reactive and less capacitive; this has proven to be a GOOD thing. The film capped (DF 1/10th typical 'lyic) ps B+ rail uses about 1/3 the uf we'd have with electrolytics. And where we'd normally use a big cap on the anode of the EF86, we have an oil-film 1/10th the value. The only place that still calls for a biggish cap is the anode of the 5687 which needs to push some serious current to drive the 300B and keep the reactive interstage choke in flux. In that spot we will use a BG 150uf VK or 68uf BG non-polar, depending on budget.
We would expect with such low uf in the ps we'd struggle with noise - NOT! The last Lux built (shown) puts out 0.3mv across the 0/4ohm taps when loaded with 4r resistor and inputs shorted! Tentlab filament supplies used. That's linestage noise territory! It's the lowest I can remember for any SE or PP amp come through here.
'Lytics truly are the devil. They slow down PRAT and muddy the sound. Now we have choke-dominant PRAT. Chokes must charge/discharge much quicker than a cap - anyone know by how much?
The noise floor changes from ear-blocking mud to see-thru (hear-thru?) way down deep. Bass is so much more detailed and that elusive 'burst' quality at low listening levels is the best ever. Transparency? no more details MIA.Oh, some wanted to see what the Lux chassis looks like built-up. Here it is. I don't think we could make the chassis any more compact. Yes it heavy. You get a lot of lbs/$ with this one.
Regards
Brian
Take control! DIY.
Edits: 10/28/07 10/28/07Follow Ups:
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