Working on a couple of flangers and have my regular old tan 5-10% tolerant resistors, but another build calls for 1% (which I'm fine with). But I started wondering if I'd be better off using 1% in the other builds too. I'm sure it allows for more consistency, but would it be that noticeable otherwise?
Quote from: Bucksears on July 31, 2012, 07:24:42 AM
Working on a couple of flangers and have my regular old tan 5-10% tolerant resistors, but another build calls for 1% (which I'm fine with). But I started wondering if I'd be better off using 1% in the other builds too. I'm sure it allows for more consistency, but would it be that noticeable otherwise?
the % only means something if you're too lazy to measure the resistors.
a 10% 100K that measures 99K is the same as a 1% 100K that measures 99K.
bottom line, measure a bunch till you get one that's close if you think it matters. every circuit is different, so there's no real answer.
In the end, you'll probably be tweaking resistors to hit target voltages, anyway.
...or you could always use a trimpot to set the value almost exactly.
Different percentage means not only the spread of values but also different temperature coefficient (ppm).
In some places it can be important.
Not to mention all of the 1%s I can get are metal film, whereas the others aren't. Metal film is always better noisewise.
Quote from: asatbluesboy on July 31, 2012, 08:26:00 AM
Metal film is always better noisewise.
unless you WANT the shot noise... :icon_twisted: (some people do- read some of the amp forums... ;D )
david
I've never had any problems using 5% resistors. When I measure new manufacture ones they usually are pretty close to the value they are supposed to be, within 2-3% of the marked value.
Quote from: Paul Marossy on July 31, 2012, 11:40:28 AM
I've never had any problems using 5% resistors. When I measure new manufacture ones they usually are pretty close to the value they are supposed to be, within 2-3% of the marked value.
This is not surprising, variation of the resistance (as a random value) is distributed by the Gauss curve.
(http://mathsforeurope.digibel.be/images/Gausscurve1.gif)
Quote from: KMG on July 31, 2012, 12:32:24 PM
Quote from: Paul Marossy on July 31, 2012, 11:40:28 AM
I've never had any problems using 5% resistors. When I measure new manufacture ones they usually are pretty close to the value they are supposed to be, within 2-3% of the marked value.
This is not surprising, variation of the resistance (as a random value) is distributed by the Gauss curve.
(http://mathsforeurope.digibel.be/images/Gausscurve1.gif)
In my mind, it's because manufacturing these days is much more consistent than it used to be back in the day. But you have a point...
Some more on this topic here:
http://www.eevblog.com/2011/11/08/eevblog-215-gaussian-resistors/
I can't find Gaussian resistors at Farnell or Digikey... where are you getting them from? :icon_redface:
To answer the question directly: I do.
I use these most frequently:
http://uk.rs-online.com/web/p/through-hole-fixed/0148663/
I don't know whether you guys are buying 5% resistors for some incredible price, but to me this seems cheap enough that I wouldn't bother using anything else. Anyway, resistors aren't where the money gets spent, so why get tight about a few pence? If it was about "lowest possible cost" we'd be dumping footswitches and fancy jacks. But we don't, 'cos it's not.
I don't doubt that circuits built with 5% or 10% resistor values all work fine (as they should if the designer is any good) but with decent, reliable, low noise 1% metal film resistors easily available and cheap, I really don't see any reason *not* to use them.
Tom
Quote from: KMG on July 31, 2012, 12:32:24 PM
Quote from: Paul Marossy on July 31, 2012, 11:40:28 AM
I've never had any problems using 5% resistors. When I measure new manufacture ones they usually are pretty close to the value they are supposed to be, within 2-3% of the marked value.
This is not surprising, variation of the resistance (as a random value) is distributed by the Gauss curve.
(http://mathsforeurope.digibel.be/images/Gausscurve1.gif)
I have some 1% resistors here and there are 2% ones that are culled from the distribution above, so the Gaussian curve is modified by removing all the values closer than 2% or certainly 1%. You are left with values that are 2% to 5% above the nominal and 2% to 5% below the nominal. I recall one project leader having to re-do his Monte Carlo simulations, deleting the tighter values just because of this. And the Gaussian does not eliminate anything beyond +5% or -5%, but the sorting at the factory does.
i am using 1% resistors only because they are almost free in the small quantities i use them but recently i thought about using 5% resistors to get back some more vintage "uncertainity" into some of my synth module builds