My foray into the Land of High Efficiency

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...

20190103_191459.jpg20190103_191512.jpg20190103_191532.jpg
 
"Happy Wife, Happy Life". ;)

Really cool journey. I kind of went down a similar path with the FrankenKlipsch. Kept the Belle bass horn, the stock AA crossover and the stock mid-driver. Added the Community SRH90 big mid-horn (which is a lot more comfortable at the 500hz crossover point than the stock Klipsch mid-horn) using the stock Klipsch driver and the Sequerra T1 ribbon tweeters.

Our mentor in these matters, @mhardy6647 , has done similar wonderful things with his FrankenAltec experements.

Remember that this is SCIENCE! :)

At least that's what I keep telling my Bride. ;)
 
very cool; thanks for the write-up. also tried a horn experiment and really liked the result. i'm a big fan of those little class D amps; detail, clarity, low $. listening to an allo volt D+ as i type this!

now maybe stands to get the JBLs up a bit?
 
Yeah, getting the voofer cabinets off the floor might help. Although right now the horns are fairly close to ear level with my current chair, which is fairly low-slung. Also getting them away from the back wall would help as well, but I'm pretty cramped in this room as it is. It's my den / work room, and doubles (triples?) as the guest bedroom.
 
Easy solution (well, easy-ish):

1. Build a framework around the speakers with four 1.5" diameter wooden posts and a wooden cap on the bottom and top
2. Stick a black speaker fabric 'sock' around the speakers
3. ???
4. Profit

Actually, it seems like a new cabinet with a baffle for the horns (open baffle, perhaps) might be a good longer-term option. You could gussy them up in a way that they are aesthetically pleasing so that they have a higher WAF, which might be the foot in the door. Also, by building new cabinets, you could keep the existing cabinets pristine so that if you want to sell down the line, you can do so.
 
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Very cool, keep tweaking these and I bet you will figure a way to get them into the liiving room ... wink wink nod nod...
I have wanted to hear the bowtie horns for a while, I read comment on them from time to time.
Thanks for sharing.
 
It's probably going to take a different house, with a family room or open basement area to really get the speakers the proper room they need to run. One good thing about the present placement is that I've never heard low-volume dynamics like this.
 
So I got an idea. I have an older, high-ish end Denon AVR that wasn't doing much. The HDMI board went duff sometime in the past, which is why I was able to score it from, literally, a dumpster. But all the audio features work fine, and it sounds good, for an AVR. I decided to use it as basically a giant DAC/preamp, in 2-channel mode. I'm using a Chromecast Audio as a source, running the digital optical feed into the AVR.

Whaddaya know, it works! I would even say it works rather well. The noise level is basically down to inaudibility, and the audio quality is up a significant bit. The next step is to bring my Schiit tube preamp and DAC into the system (in place of the AVR), and see what difference that makes. If it kicks up the quality another significant amount I will find a way to put the AVR into the living room system, and keep the Schiit gear with the JBL/Emilar system.
 
The Denon AVRs seem to be pretty nice from my limited exposure.
Hmm -- Is that apostasy? ;)
Hmm -- Is there an adjective form of the noun apostasy? Perhaps apostatic?
Need.
More.
Coffee.
 
I dunno, man. I googled that and the first link was to an article titled "Hylomorphism and the Metaphysics of Structure", from the periodical Res Philosophica, Non-Aristotelian Themes in Metaphysics and the Philosophy of Mind.

Mean anything to you?
 
So I did it -- I moved my Schiit. (The inner 11-year old in me is giggling uncontrollably...) Actually, the Bifrost Uber, Saga, and Elan Z660 amp moved into the horn system. And, the Denon AVR moved out into the erstwhile main system, now the A/V system. Also I brought in the turntable, since it was positioned fairly awkwardly before, it was not terribly convenient to play vinyl, and far more convenient to play, well, everything else.

The setup now revolves around the Saga preamp, being sourced by the turntable (Denon DP-52F with Panasonic strain gage cartridge), CD player (Sony DVP-NS900), and Chromecast Audio, the latter two running through the Bifrost Uber DAC. Downstream of the preamp is a TDM CX24-4 crossover, then four channels of the six-channel Elan Z660. So the woofers are getting straight 60W max, and the horns are being run through the 10dB pad resistor voltage divider.

If the sound was good before (it was "fun"), it is a significant order of magnitude better now. System noise is virtually non-existent, and clarity is outstanding. Also there's a "depth" to the music that I've rarely heard in my system. Perhaps it's a function of a very low noise floor, or a function of the preamp tube, or very low upstream distortion, or some permutation thereof. All I know is that it sounds right. Very right. As I said in a previous post (I think), I had no idea 45-year old horns and drivers could be this amazing.

Note the custom acoustic treatments:20190120_060252.jpg20190120_143055.jpg20190120_143205.jpg
 
So I did it -- I moved my Schiit. (The inner 11-year old in me is giggling uncontrollably...) Actually, the Bifrost Uber, Saga, and Elan Z660 amp moved into the horn system. And, the Denon AVR moved out into the erstwhile main system, now the A/V system. Also I brought in the turntable, since it was positioned fairly awkwardly before, it was not terribly convenient to play vinyl, and far more convenient to play, well, everything else.

The setup now revolves around the Saga preamp, being sourced by the turntable (Denon DP-52F with Panasonic strain gage cartridge), CD player (Sony DVP-NS900), and Chromecast Audio, the latter two running through the Bifrost Uber DAC. Downstream of the preamp is a TDM CX24-4 crossover, then four channels of the six-channel Elan Z660. So the woofers are getting straight 60W max, and the horns are being run through the 10dB pad resistor voltage divider.

If the sound was good before (it was "fun"), it is a significant order of magnitude better now. System noise is virtually non-existent, and clarity is outstanding. Also there's a "depth" to the music that I've rarely heard in my system. Perhaps it's a function of a very low noise floor, or a function of the preamp tube, or very low upstream distortion, or some permutation thereof. All I know is that it sounds right. Very right. As I said in a previous post (I think), I had no idea 45-year old horns and drivers could be this amazing.

Note the custom acoustic treatments:View attachment 10164View attachment 10166View attachment 10167
Outstanding! :)

I am very happy that you are enjoying your new system configuration! :)

Time to kick back and enjoy. :)
 
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