I'm trying to dial in some sweetness in the upper frequency range (8K-16K?) but not sure where to start. Tubes? Circuit? Tweeters? Crossover?
Amp is an ST70 "kit" build with VTA driver board (no upgrades), Triode OPTs, Dynakit PT. Mullard GZ34, Sylvania/JAN Phillips 12AT7 preamp tubes, JJ EL34 power tubes. Speakers are Pioneer CS-77A. Input is via an Echo Mia audio card. (The system is used in my home recording studio.)
So far I've tried the following:
- Replaced the surrounds on the original tweeters. No help really. I think the original tweeters are horrible.
Replaced the tweeters with some Goldwood paper cone tweeters from Parts Express. Even at $5 each, these were a significant improvement over the original tweeters. They just don't seem to have any "air" or "space."
Tried a few NOS preamp tubes (RCA, Sylvania, JAN Phillips) and like the combination of Sylvania voltage amp/JAN Phillips PI best so far.
In browsing the forum, I've seen more information than I can possibly digest in a year. Any suggestions on how to dial in upper frequencies that are crisp and airy without causing listening fatigue? Better power tubes? Tweeter recommendations? Crossover overhaul? Any suggestions are much appreciated.
Thanks,
Norm