How to match resistors

Buy about a zillion resistors and measure the resistance of each until you have closely matched groups in whatever QTY you need. Ok, so a zillion is slightly overkill, but overkill is better than failure, so usually 6 times as many parts as you actually need OR exactly as many as you need in the next better precision rating than you need. 

On that note, aside from bragging rights 1% resistors are already matched to better tolerances than the vast majority of audio applications require. The whole emphasis on "matched" resistors came from way back when, when 5% resistors were the norm, and 1% resistors were EXTREMELY expensive. Hand matching a bunch of 5% resistors to 1% tolerances was less expensive than buying 1% parts off the shelf so thats what people did. with 1% resistors so cheap (like $0.18 for vishays... less for some others) it makes no sense to hand match anymore.

If you do *need* better accuracy than you can get with 1% resistors, use a resistor and a trimmer, its cheaper than 0.1% resistors which never come in the exact value you need anyways. 

Summarized: 

Unless you have VERY specific needs buy exactly as many 1% resistors as you need and only check resistance to make sure they put the right thing in the bag. If you are new to this whole DIY electronics thing buy twice as many as you need in case you mess something up. If you are experienced buy twice as many as you need - your odds of screwing something up are lower, but it never hurts to have spares and you may as well have enough spares to make a stereo pair out of at a later date...

what he said, all except for the lower values, like 0r47 source resistors, or for instance the resistors in parallel with the load in an SRPP amp centering the load. values lower than 1r are not reliably matched with a dmm just by itself, but rather with a current source and the dmm, then measuring the voltage drop across them. generally 1% is fine and often as mentioned above quality 1% resistors are generally tighter than 1%, but sometimes low value power resistors are not available in 1% unless very expensive

Just a tip, you can keep the measured resistors in a plastic perforated board as shown in the picture, it helps me to keep the resistors for future use, I don't have to re-measure them again.

http://www.head-fi.org/forum/thread/295983/tutorial-how-to-match-resistors-up-to-0-01-using-a-cheap-dvm#post_3796755

And matching channel to channel is far more important than absolute accuracy in most audio application.

And as a side note, go take a look at the specs on a potentiometer and then you can see why in most cases you are fighting a losing battle.

Quote:

Originally Posted by cobaltmute 

 

And as a side note, go take a look at the specs on a potentiometer and then you can see why in most cases you are fighting a losing battle.

This. 

Even a very good one, like an alps RK-50

thats one reason why i have eliminated them entirely from my signal chain :D i have perfect channel and phase matching from source. phase to phase is the most important, i wouldnt bother so much if it was just channel to channel balance. absolute accuracy is rarely important, relative accuracy is where its at with just about everything imo. which is why the current source method is so good and so simple for low values, pick a reference resistor and match voltage drop to that, simple

digital, but you guessed that; not much good for you nikongod, what with your love for vinyl

I run my vinyl system through my digital system for the personalized EQ I like to use :) It sounds great!

Still haven't gotten into digital attenuation though. Maybe someday.

Quote:

Originally Posted by cobaltmute 

And matching channel to channel is far more important than absolute accuracy in most audio application.

http://www.edn.com/article/509250-7_solution.php

Here's an insightful/funny article about the search for accurate/precise resistors.