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Stax F-81: Make a great speaker better?

Just bought a pair (second time). They sound glorious with Manley 200's. First time around amplification was not up to par(Moscode600).Looking for intelligent opinions on ways to make this incredible speaker better. Power cords(so far MIT Z-cords have made a significant if not overwhelming improvement, speaker cable(Siltech, power conditioners(they do sound a bit more refined plugged into a Power Wedge). I am most curious about a mod that I read about and can't remember where: the removal of the RC network in the power supply. Thank you all ahead of time.
frogman
kr489ec
12 posts
 
Don't do it. The only mod I found effective was a compensation filter for the mid-bass suck-out. The filter makes the F81 quite flat but power handling is compromised. Use the filter plus a sub to solve that.
frogman OP
7,476 posts
 
Kr4, thanks for the advice. Could you describe this filter? And what sub do you think can keep up with this speaker? I am looking at a Kinergetics SW200.
justlisten's avatar
justlisten
489 posts
 
I never found a sub that could keep up with this speaker, I tried, Muse 18, Janis, and other less notable. The best advise I got was from the seller who said dont try to add bass as you will ruin the qualities of this fine speaker. I ran it with OTL's Counterpoint SA4's and the sound was glorious. I regret to this day I sold them.
kr489ec
12 posts
 
The problem with using any sub is the interface. Since the F81 has a significant amplitude suckout in the mid-bass and peak in impedance at 200Hz, one must compensate for both of these in order that adding a sub does not make things worse, as it usually does with F81s. The circuit is a 6dB/8vo boost from 500Hz down to 100hz. Below that, I ran it flat (w/o sub) or rolled off at 24dB/8vo (with a sub). Kal
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