Impedance Matching

[FALKEN]

Generally, the input impedance should be 10 times or greater than the source impedance, so that most of the signal goes through the signal path, and so that frequency variations are minimized.

wait; wait; fuck my mind is boggled;

so you want the preamp impedance to be 10x the mic impedance, or you want them matched?

 

[FALKEN]

How do we folks with RNPs or Syteks or Blue Tubes....cheap stuff such as that, take advantage of impedence matching? Is this a stupid question? What is the effect on the sound of a mic?

I think he means pres with non-adjustable impedance. which is what ive got. what are we to do?

 

[FALKEN]

Maybe we need some variable output impedance mics also to play with.

I have an old shure 51 with variable impedance. I typically put it on the lowest one b/c I thought it gives the most signal?

 

[mshilarious]

I have an old shure 51 with variable impedance. I typically put it on the lowest one b/c I thought it gives the most signal?

No it should have a hotter signal on the high setting. However there are big differences in tone, much more so than the level. Ordinarily you should use the M position with a modern preamp.

 

[Warhead]

http://www.shure.com/support/technotes/app-impedance.html

War

 

[FALKEN]

http://www.shure.com/support/technotes/app-impedance.html

War

dont want to sound thick-skulled, but, does this mean with tube pre's you want to match and with transistors you want 10x? thanks.

 

[Warhead]

No, they're saying Bell Labs reduced the amount of tube amps needed by matching the impedences. It carried the signal stronger / further.

War

 

[Richard Monroe]

I've got an Avalon AD2022, which offers input impedence of "mic", which if I recall, is a nominal 2500 ohms, 600, 150, and 50 ohms. When you switch impedence, the effect is as dramatic as if you switched mics. And yeah, I often use 600 on dynamics.-Richie

 

[Marik]

dont want to sound thick-skulled, but, does this mean with tube pre's you want to match and with transistors you want 10x? thanks.

Matching means that the load is higher than a source. Usually, 5x load impedance is sufficient. Some circuits (tube ones, or transformer coupled), as well as some passive microphones (like dynamics or ribbons), like much higher loading.