The ratio is a minimum. Ideally you want a minimum of 10:1. Anything over that is fine.
Best,
Erik
Best,
Erik
Impedance matching with tube amp
I have a Mccormack DNA 0.5 which has an input impedance of 100kohm. I'd like to get the Schiit Saga preamp, which has an output impedance of 180 ohms. Now, I've read about the 10:1-100:1 ratio of input:output impedance for power amps and preamps, so this wouldn't quite fit that range of ratios. Would this still be a good option, and if not, what other (<$500) tube preamp options do I have?
Thanks!
Thanks!
- ...
- 12 posts total
"this wouldn't quite fit that range of ratios" suggests a misunderstanding of the ratio "rule". The pre-amp's output impedance doesn't have to fall within 1/10th and 1/100th of the power amp's input impedance, it's that the ratio of power amp input impedance to pre-amp output impedance should be 10 to 1 in the opinion of some, 100 to 1 in the opinion of others. But that 180 ohm figure for the Saga is a nominal one, not it's complete one. Even so, 180 ohms times 100 is still only 18k, far less than 100k! |
To clarify, If you go too low in the ratio, say 5:1 you run into the real possibility that the mismatch will cause significantly non-flat frequency response. Sometimes the volume control settings can radically alter the frequency response in minimalist tube preamps with the wrong amp. You can see the effect in many Stereophile reviews like this one: https://www.stereophile.com/content/conrad-johnson-premier-17ls-line-stage-preamplifier-measurements |
- 12 posts total