stupidhead Posted January 29, 2016 Report Share Posted January 29, 2016 I suspect the topic title opens this dialog well enough but let me be more specific. I have a shopping list for various caps and resistors I have submitted. Of all the various resources like Madisound, Erse, Meniscus, PE.... I haven't found one that has precisely what I am looking for in total. Either out of stock or not exact values available for entire list.I have seen folks say such and such is close enough, for example in my recent search I was seeing 3.9uf when searching for a 4uf. Would that be okay? This sort of thing has cropped up before in my mind as I have made more orders over time and I have often said to myself, could I use something close enough?Remember please, I have submitted my order so I am not looking for options at this time, more wondering about this topic for the future.Geoff Link to comment Share on other sites More sharing options...
ra.ra Posted January 29, 2016 Report Share Posted January 29, 2016 When you factor in that even original caps had some stated plus-minus tolerance accuracy, you can begin to understand that getting "close" to original cap values is usually good enough for replacements. Having said that, I still try my best to conform to original spec values for components, but that's mostly because I have neither the knowledge, equipment or skill to perform comparative measurements. Also, it's important to keep in mind with these vintage restorations, that the aged drivers are most probably not performing exactly as they did when they left the factory.About resistors, they are very easy to measure before considering replacement, but I do tend to adhere to JKent's belief that sometimes a slight increase in wattage (say, from 5w to 10w) can often be a prudent move to ensure longevity. Link to comment Share on other sites More sharing options...
Carlspeak Posted January 29, 2016 Report Share Posted January 29, 2016 A cap is not a 'drop off a cliff' device. It creates a curved roll off in the FR.BTW, 0.1 uF diff. between 3.9 and 4.0 is only 2.5%. Most commercial caps are 5% tolerance or higher. Dayton does offer a 4.0 uF cap however for your future use files.Caps can be paralleled to get a huge non-st'd variety of uF values. Link to comment Share on other sites More sharing options...
JKent Posted January 29, 2016 Report Share Posted January 29, 2016 Old electrolytics were often marked with their tolerance: -10% +75%. Draw your own conclusion Link to comment Share on other sites More sharing options...
owlsplace Posted January 29, 2016 Report Share Posted January 29, 2016 Old electrolytics were often marked with their tolerance: -10% +75%. Draw your own conclusion I can roll with that one -- "more is better" Then there is shunting electrolytics with film caps ... Link to comment Share on other sites More sharing options...
donquixote99 Posted January 30, 2016 Report Share Posted January 30, 2016 I'd actually be a bit more concerned with cap values being as equal as possible, right and left. But even with that, I imagine being within 10% is probably fine. Link to comment Share on other sites More sharing options...
stupidhead Posted February 1, 2016 Author Report Share Posted February 1, 2016 thanx folks, these responses are pretty much what I suspected.About resistors, they are very easy to measure before considering replacement, but I do tend to adhere to JKent's belief that sometimes a slight increase in wattage (say, from 5w to 10w) can often be a prudent move to ensure longevity. On resistors, the only question I still have is the increase in wattage. I understand and have seen pics showing evidence of over heating a low wattage resistor. Is there any problem choosing replacement resistors that are more than a slight increase? Say from a 5 watt rating to a 25. I suspect that the physical size is likely not much greater than the 5 but is there an engineering reason not to "upgrade" to a much higher rating?Geoff Link to comment Share on other sites More sharing options...
owlsplace Posted February 9, 2016 Report Share Posted February 9, 2016 On 2/1/2016 at 5:16 AM, stupidhead said: thanx folks, these responses are pretty much what I suspected. On resistors, the only question I still have is the increase in wattage. I understand and have seen pics showing evidence of over heating a low wattage resistor. Is there any problem choosing replacement resistors that are more than a slight increase? Say from a 5 watt rating to a 25. I suspect that the physical size is likely not much greater than the 5 but is there an engineering reason not to "upgrade" to a much higher rating? Geoff You just have to be aware of changes in inductance that will affect the crossover. Here is a reference: http://www.resistorguide.com/inductance/ Roger Link to comment Share on other sites More sharing options...
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