Hello to all,
I finally managed to bring my project to materialization. OB speakers with 2x LO15, B&C DE250 & Autotech SEOS 15″ each. To exactly “finish” it will require some more time with EQ, but results were promising even the first day.
I’d like to share my experiences and ask a couple of questions. For the first, all four drivers seem to be flawlessly made and untouched from overseas shipping.
A week after I’m much closer to complete satisfaction, but this is only first week of a process that may take months. Overall these speakers are showing significantly greater potential than my previous Emerald Physics CS2, which in my room were quite excellent and among those best I heard anywhere. CS2 completely cured any audiophilia nervosa I might had being more than 20 years in audio, and if I was not plain curios enough while at the same time being able to stretch for 4x AE LO15s during last year, I could live with CS2s very happily for many more years. Briefly for those who are unfamiliar with EP CS2, this is the same concept and size like my new AEs, but with 2x Eminence Alpha 15A, Selenium D220Ti and Dayton 12″ round waveguide. In my opinion CS2 is still the most significant recent consumer speaker, clearly showing a strength of a clever concept and skill over just throwing more money in a wrong direction.
As before, speaker is powered with >100 W per channel MOSFET for lows and 2A3 SET for highs, crossover is Behringer DCX2496 with full Selectronic mods. Signal is kept digital all the way to DCX, then after it gets out as analog I have 4-channel step-attenuator before amplifiers. I connected LO15s 8 Ohm coils in series at each driver, than two drivers parallel to the amplifier. That should give 8 Ohm total load.
From the front, new speaker looks almost exactly like this rendering, I’ll post real photos some other time. Tweeters also have open backs so it is a dipole all the way.
As a quick description of a sound I get now it is somewhat of a mixture of CS2 sound I had earlier, and of my impressions from auditioning JBL Everests.
In comparison with CS2, new one gives even clearer sound throughout the spectrum, sound fills the room more fully and evenly, dynamics are also a bit better, and low end has more energy. I can always turn bass higher on CS2 too, but this one sounds more free from compression down low regardless of bass quantity. Also, I seem to get less (or none…) “structural” annoyances. This new baffle should be better than CS2 – new one is 2″ baltic birch plywood baffle plus quite heavy steel backbone. In the beggining, even with suboptimal EQ scheme and some clearly present peaks, sound was still quite listenable and easily flowing. While at CS2 I really needed to nail the EQ right, with new speakers there seem to be a larger margin for error while still hearing a good music.
I started with XO and EQ scheme exactly as with CS2. Surprisingly, it was quite good. Later I decided to go from scratch and it is now better, but some corrections are still very close to ones with CS2. I guess those have room related cause. I left XO as 48db/oct Butterworth. CS2 have LP point at 1.24k, and HP point at 1k. For new ones I lowered both to 970 Hz.
That is my first question. Should I also put new LP a bit higher than HP (say LP at 1.1 k while HP is at 970 Hz), and why is that so at CS2? I know I can experiment, and I had and I will, but number of combinations of XO points with tracks at where I may actually hear the difference is vast, so I would like to narrow it down theoretically first.
Also is there any scheme of a LO15 motor structure? I tell people LO15 is a dual-coil design, but cannot really describe how it looks like inside.