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Vinyl Asylum Welcome Licorice Pizza (LP) lovers! Setup guides and Vinyl FAQ. |
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Vinyl Asylum Welcome Licorice Pizza (LP) lovers! Setup guides and Vinyl FAQ. |
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In Reply to: RE: Here are some additional measurements.... posted by John Elison on October 5, 2009 at 20:04:09:
Well since I don't and you presumably don't have the Soundhifi unit in hand to test all we are left with is speculation.
If I could speculate a bit: take a look at the data sheet I've linked of the National vltage regulator which Soundhifi claims to use, specifically the ripple rejection ratio found in Electrical Characteristics and the graphs of ripple rejection, output impedance and load transient respnse found in the typical performance characteristics section.
Based on looking at this data, and the assumption that Soundhifi are fairly competent designers, the Soundhifi claims don't seem completely ridiculous in my opinion. Of course the actual performance will depend greatly on alot of things I have no knowledge of such as the regulator input ripple value with typical loading, layout, etc.
Just to toss some numbers out for the sake of argument if we were to consider a 100mA strobe current at 100Hz (I know the strbes squareish pulse probably has much higher frequencies but this regulator has great broadband performance around the probable frequencies present) it would appear that output impedance could be around 3milliohms (per graphs) yielding 0.01*0.003=0.0003V ripple. This is nearly 50dB down from the 74mV ripple shown in the Soundhifi plot on the webpage. Not to far from the claimed 60dB and perhaps they are using tricks to improve on the graphed performance and they are certainly incorporating beefier transformers and filter caps than are found stock in the Technics power supply.
As mentioned this is all just speculation, of course, but I would argue that it also serves a a sort of quick and dirty sanity check of the Soundhifi claims which don't appear to be all that far fetched by my estimation...unless I am mistaken.
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Follow Ups
- RE: Here are some additional measurements.... - Ugly 10/5/0921:40:19 10/5/09 (0)
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