As I posted about some time back, I acquired a very nice pair of JBL L55 speakers. I really liked them, I thought they sounded lovely, especially in a *warm fuzzy* sort of way. But my desire had been to run the LE14A woofers with a nice set of horns, through my active line-level crossover (TDM 24CX-4). Eventually, through my good buddy and audio provocateur, @ICTWoody, I was able to acquire a set of Emilar EH800A "Bowtie" horns and EA-175 drivers. Unfortunately one of the diaphragms was blown, and couldn't be repaired by me -- although I tried mightily to do so. So I broke down and spent outrageous sums of money (for me, that is) on a NOS pair of Radian diaphragms so that both speakers would be essentially new, and not mismatched. They came from a Canadian supply house, QComponents.ca.
Through trial and lots of error I was finally able to get the combination dialed in fairly well. Originally I tried level matching the woofers and horns by dialing the HF output level WAY back on the crossover. This worked sort of, but there was a lot of hiss through the horns, and they didn't seem to scale well with the woofers. And as the horns are run off a cheap-but-decent Class-D amp (TPA3110), I was terrified that any DC pops through the amp could damage the brand new diaphragms. So to better address this problem I wound up putting a voltage divider on the compression drivers to pad them down about 10dB. This allowed me to bring the HF level back up to even with the LF level in the crossover, which really balanced out the scaling issue as the master volume went up and down. It also eliminated all but the faintest trace of hiss through the horns, which is no mean feat.
Getting the crossover point right was a bit challenging as well. I'm just glad I have an active crossover! I settled on approximately 1KHz as the point. The crossover has 24dB/octave slopes. Too high, and the midrange was too thick. Too low, and the overall sound was too thin. But this seems to be the "just right" point. I think the "thick mids" issue could partly be the un-braced L55 cabinets. I added more damping material to them, and that helps, but I feel that good cabinet bracing could help a lot as well.
At this point they're not quite perfect, but IMO really good. I'm shocked, in a pleasant way, how natural and smooth the horns sound. There's not a hint of the classical "horn-y" sound that is so off-putting to me. I honestly didn't know this could be, or rather had been, achieved. My overall experience with horns has been very limited. 10 years ago I built a pair of the famous Zilch-inspired E-Waves, and really liked them. Unfortunately that system was broken up and sold when we moved cross-country. I've also had a pair or two of Klipsch along the way, which didn't help the cause of horns at all. But if THIS is what it's all about, then count me as a believer!
There are quite a few improvements that could be made to the system, such as using a *real* preamp and source, rather than just my Samsung Galaxy. I'm driving the speakers with, as noted above, Class-D amps, to wit: Sure TPA3110 (12W) on the horns, and Sure TPA3116D2 (25W) on the woofers. These amps are very clean and smooth. They definitely do not add character in the way that a tube amp would, but do not negatively effect the system either. I would love to put a tube preamp in front of the crossover, such as my Schiit Saga. I think it would flesh out the sound in a great way. Also there's the issue of cabinet bracing for the L55's. I'd like to do that in a minimally subtractive way, regarding box volume. I also want to keep them stock (or rather able to be reverted to bone stock) for potential resale value. So I'll probably run them as-is, and simply enjoy them.
This has been (and still is!) a great and successful "experiment". I've learned a bunch about compression drivers and horns, which heretofore I had regarded as one of the mystical dark arts. Who knows, they may well be. But the sound is so full of life and energy, and so very smooth. The only major "problem" is that my wife regards their aesthetics with a scornful eye. So at least for now the speakers are relegated to a secondary bedroom that is much too small for them. But at least I get to enjoy them, albeit at a fairly low level. On the other hand, my wife absolutely loves the look of the Vandersteen 2ce speakers that currently inhabit the living room, and has told me in certain terms that they're NOT leaving. So I have that going for me...
Through trial and lots of error I was finally able to get the combination dialed in fairly well. Originally I tried level matching the woofers and horns by dialing the HF output level WAY back on the crossover. This worked sort of, but there was a lot of hiss through the horns, and they didn't seem to scale well with the woofers. And as the horns are run off a cheap-but-decent Class-D amp (TPA3110), I was terrified that any DC pops through the amp could damage the brand new diaphragms. So to better address this problem I wound up putting a voltage divider on the compression drivers to pad them down about 10dB. This allowed me to bring the HF level back up to even with the LF level in the crossover, which really balanced out the scaling issue as the master volume went up and down. It also eliminated all but the faintest trace of hiss through the horns, which is no mean feat.
Getting the crossover point right was a bit challenging as well. I'm just glad I have an active crossover! I settled on approximately 1KHz as the point. The crossover has 24dB/octave slopes. Too high, and the midrange was too thick. Too low, and the overall sound was too thin. But this seems to be the "just right" point. I think the "thick mids" issue could partly be the un-braced L55 cabinets. I added more damping material to them, and that helps, but I feel that good cabinet bracing could help a lot as well.
At this point they're not quite perfect, but IMO really good. I'm shocked, in a pleasant way, how natural and smooth the horns sound. There's not a hint of the classical "horn-y" sound that is so off-putting to me. I honestly didn't know this could be, or rather had been, achieved. My overall experience with horns has been very limited. 10 years ago I built a pair of the famous Zilch-inspired E-Waves, and really liked them. Unfortunately that system was broken up and sold when we moved cross-country. I've also had a pair or two of Klipsch along the way, which didn't help the cause of horns at all. But if THIS is what it's all about, then count me as a believer!
There are quite a few improvements that could be made to the system, such as using a *real* preamp and source, rather than just my Samsung Galaxy. I'm driving the speakers with, as noted above, Class-D amps, to wit: Sure TPA3110 (12W) on the horns, and Sure TPA3116D2 (25W) on the woofers. These amps are very clean and smooth. They definitely do not add character in the way that a tube amp would, but do not negatively effect the system either. I would love to put a tube preamp in front of the crossover, such as my Schiit Saga. I think it would flesh out the sound in a great way. Also there's the issue of cabinet bracing for the L55's. I'd like to do that in a minimally subtractive way, regarding box volume. I also want to keep them stock (or rather able to be reverted to bone stock) for potential resale value. So I'll probably run them as-is, and simply enjoy them.
This has been (and still is!) a great and successful "experiment". I've learned a bunch about compression drivers and horns, which heretofore I had regarded as one of the mystical dark arts. Who knows, they may well be. But the sound is so full of life and energy, and so very smooth. The only major "problem" is that my wife regards their aesthetics with a scornful eye. So at least for now the speakers are relegated to a secondary bedroom that is much too small for them. But at least I get to enjoy them, albeit at a fairly low level. On the other hand, my wife absolutely loves the look of the Vandersteen 2ce speakers that currently inhabit the living room, and has told me in certain terms that they're NOT leaving. So I have that going for me...