Ok, a little update. I have a little 40 w desktop amp, a couple choices of capacitor (2.3 uF and 6.2 uF), and two choices for super tweeter (the Linaeum dipole ribbons, and a bunch of cheap surface-mount Dayton Audio ribbons from Parts Express), with quick-disconnects so I can change things around, and have been trying different combinations with the 901s.
I have not yet found a solution that I’m ready to settle on, but I do think this is a promising enough direction to continue. I’ve also learned that this is a very idiosyncratic sort of thing, so I suspect my ultimate solution will be separate from the 901s rather than permanent modifications to them.
I’m not using instrumented testing at all, my sole goal is to please myself with the kind of music I listen to and to compensate for my hearing deficiencies (poor from 10 kHz to 13 kHz, almost nil above 13.5 kHz).
To describe what it’s like when these experiments are “working”: put “Wise One” by John Coltrane (on the Crescent album) on your stereo.
The drummer is Elvin Jones, and his primary instruments for the piece are his cymbals. It’s some of the loveliest, most expressive, and lyrical cymbal work I’ve heard by him. Jones was a master of the cymbals. With the stock 901s, you can hear him playing the cymbals over on the right side of the stage, but they are muffled, even faint. The sound is really dominated by Coltrane’s horn from the left. Coltrane’s playing is deliberate, grave and full. It’s one of my favorite Coltrane albums, and for most of my life I’ve been content to focus on the saxophone and just register the cymbals as a minor, and soft, part of the music.
However, Jones was a powerful drummer. The few videos I’ve found of him playing in Coltrane’s mid-sixties band, he isn’t delicately tapping on his cymbals. He played them hard and strong, sweat pouring down his face, matching Coltrane’s passion and presence in a way that, in my opinion, Jimmy Cobb did not. If we were sitting in a jazz club in 1965, maybe one row of tables from the stage, and Jones was in full cry, his cymbals wouldn’t be muffled or faint. We’d hear every clash and ride, bell and ring, all the detail and attack. The impact and presence of Jones would be second in that band to only Coltrane himself.
What’s wrong with what I hear on my stereo? Well, first of all I’m listening to Bose 901s which uses full range drivers, and even with heroic EQ have rolled off by 10 kHz and certainly up where the cymbals’ harmonics live. The speakers RWebb recommends would surely be better. But more fundamentally, the recording was mixed to put Coltrane out front and the rest of the band way in back. Even using good headphones, it sounds that way. The background sound of Jones’ drumming is what the recording engineer intended, I’ll guess, but it’s not what Jones intended, I’ll wager.
And it is not how Coltrane’s band sounded live - not that I ever saw them, but from my time in jazz clubs and from the few live recordings of the band that are really live, not with a “studio audience” and miked up to be mixed later. Such as this one - by the way, Naima starts at 9:15 - where you can hear how forward Jones really sounded when he was on it.
https://youtu.be/i_-RNjw7Bvo
So, my little experiments allows me to pull Jones’ cymbals out of the background, to compensate for my own degraded hearing, and to hear a level of detail in many long-familar recordings that makes it a pleasure to listen to them again. It may sound artificially bright or hard to someone with better hearing or with a preference for a mellower sound, so I’m keeping the super tweeter on its separate amp, easy to turn down or turn off. It only makes a difference on about 10% of the music I listen to.
The Linaeum isn’t a great super tweeter, by the way - it is more of a high-mid to treble driver, in the original speaker it was crossed around 3 kHz. Crossing it at 10 kHz, it is out of its sweet spot - nice and omni directional, certainly helps, but lacks that crystalline shimmer. The Dayton ribbons have are great at the high high stuff, but have little volume, I have to turn the amp higher than seems desirable. I will be experimenting with ganging up two or three of the ribbons on each channel.