Martin Poulin
January 2018,
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Yea, I drank the cool aid.
Loved it so much that I asked for a second serving...
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I made the move to a horn based in the kitchen’s second system, and it seems it’ll be permanent!
The Low-Fi Pyle compression driver (JBL 2445 copy) and the Eminence aluminum cast H2EA exponential horn.
I added an Eminence N151 ring radiator on a B&C Me10 horn to cover 6 kHz and above.
Right now, a pair of 100 dB efficient precision device PD154 covers the 50 Hz - 600 Hz. (sealed 70-liter cabinet)
What a wonderful system it is now, and it "engages" the kitchen a lot better.
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The second system sound is now drastically different from the main room infinite baffle system. Having two systems is very nice, as I can chose which one to listen to depending on my mood.
Unlike before, where one sounded great and the other lagged in performance, and didn’t offer too much benefit, I can now select the "intimate or concert".
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Yes, upgrading the kitchen’s second system to mid and treble horn and high efficiency woofer, got me a much more dynamic playback. On some aspects, it’s far better than the main rig at a literally a fraction of the price. This hurt the pride a bit.
Sure, background noise is more prevalent, and the high gain amplifier (Krell showcase 7) doesn't help at all . I heard coloration on vocals due to a "cheap" Pyle compression driver, on a cheaper entry level exponential horn, but I also heard tremendous potential which got me excited.
So much so, that I’m enthusiastic, and as a result it requires more investigation.
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Most horns, with a passive crossover system, are heavily compromised and usually just plain suck...IMHO.
Every time, I see them at HiFi shows, I only spend a few minutes before quickly moving on, as they never quite do it for me. That is except perhaps my vague memory of the Edgar horn in ~1998 at Montreal HiFi expo. However, it’s been much to too long to for me to really remember.
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Main Audio room test system phase 1:
I just purchased a set or Radian 760PB Neo’s, mounted on newly acquired Jean Michel le Cleach' Azura horn (2" throat, 340 Hz version)
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Right now, the system is only temporary, and I use the horn from : 600 Hz -20 kHz.
With a lot of equalization on both ends, it’s just spectacular.
I'm feeding it with my Krell 300CX, a 100-pound amp, that’ll give over 300 Wrms! It also has very high gain!
I do have a bit of white noise, but once the music is playing, it's fine.
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I think that a tweeter is required on the 760, but time to properly dial it in will be considerable. I won’t bother for now.
There is also the beryllium diaphragm option on the 760 which is tempting, as is the TAD4001 or the big Radian 950PB.
People claim the beryllium doesn't require a tweeter, but it’s rather expensive to find out. So many options here.
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On the first picture, you see the JMLC horn and the big Scan Speak Revelator 32W4878 hidden behind the drape as they are mounted on a infinite baffle. The 32W4878 at 32cm diameter and only ~90 dB efficiency can’t really match the horn. You No surprise here. No plan to sell those yet, so they will be sitting for a while.
February 2018 (Horn investigation; Phase 2)
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Just finished a dual 15" bin that is ~103 dB/w to match with the horn. (4 x Fane Colossus 15XS Prime wired in parallel)
Enclosure is internally separated (two separate, identical air volume)
It was supposed to be bass reflex, but it sounded better as a sealed configuration, so I used foam insert to plug ports.
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Using my DIY 12W Mono block on the Jean Michel LeCleach' horn (a lot of equalization is required)
The Krell 300CX is relegated to energizing the dual 15" (talk about overpower...)
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14 speakers total. All are active.
What a system! Talk about dynamics and effortlessly 125 dB capable system!
Playing with six sub-woofers (four 18" and two 13"), dual 15" mid-bass, JMLC horn and 1" dome tweeter.
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Like a new girlfriend, it's easy to fall in love with a horn. However, only time will tell if my horn temptation will be a one-night stand or a long-term relationship :)
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At least, I commit the proper time/effort to see if it’ll work for me.
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Below is the second temporary setup.
It literally kicks you in the gut. So impactful, it isn’t even funny. Tinnitus creating system, for sure.
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February 2018 (3rd phase)
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Unfortunately, my audio room days are numbered.
I'm 99% sure I’m moving and will have to sell the house. (military life means constant relocation, and I'm set to be posted to Alberta. Not my call on this one.)
New house, and a new audio room. I’m hopeful it’s be bigger and have higher ceilings.
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Meanwhile, after additional research, I realized how much there is to learn about horns and their bandwidth limits.
Most horns are designed for PA systems (public address) so HiFi isn’t the first design criteria.
Doing horn and HiFi calls for off the beaten path, with big sizes and some wild guesses made.
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One thing is for sure. the Radian 760NEO PB mounted on the JMLC needs a tweeter.
With equalization, it can reach a high treble, but it doesn't have the precision to do a great job.
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I briefly tried my magnesium Transducer Lab dome tweeter. I had friends coming over to hear the new JMLC horn setup, so I had to have a tweeter playing.
It produced sound better than the horn running full range, but it was a bad match overall.
The ~92 dB efficient dome wasn't keeping up with the ~107 dB compression driver. Is this any surprise?
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I should have used the superior sounding ceramic tweeter… or even better… the beryllium tweeter, but I was lazy, and the magnesium version was handy sitting on my shelf. (the magnesium version was the worst of the three)
Honestly, I doubt results would had been much different, with the beryllium giving only 95 dB sensitivity.
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With some DIY audio threads (thanks ICG), I got two good suggestions and, decided to buy everything and try both. The price wasn’t outrageous, so buying both was an easy call, for sake of HiFi heaven.
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I used the JMLC compression driver up to ~7 kHz and where the JMLC requires more aggressive EQ, kick in a super tweeter to finish the task above 7 kHz. On a recommendation from a forum (ICG again), I ordered a pair of Beyma CP22 to try out.
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I used another compression driver which kicked in early, so when the JMLC started beaming more (~4 kHz), the treble unit takes over. Buy a small diaphragm CD for extended high (32-38mm voice coil) #2 is exactly what hORNS does with it's three-way. click here to see
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hORNS use similar JMLC as I do, (they use the 200 Hz version) and even use 4" beryllium diaphragm option for extended highs.
If their choice is to cut the big Radian 950PB and cross to another CD for treble, despite seeming contradictory, it must be for the better.
Their decision must have been carefully evaluated by their designer. Unfortunate, they didn’t disclose the crossover points. It leads me to believe #2 has a lot of potential.
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I used the Eminence N151M which I already owned, to see how it matched the Radian 760. This test is a last resort scenario as the N151M really drops in efficiency above 10 kHz, and the odds that it’ll work great are quite slim. Just more ideas than time really. The N151M remains on the shelf for now.
So, #2 is the first one to be tried. (this got delivered first)
Started with Celestion CDX1-1445 for the initial task, and mounted them onto FaitalPro STH100 Tractrix horn (boxed and painted white to visually fit the system)
The crossover was @ 4 kHz for the initial test (could have tried 7 kHz as well but needed to burn-in the Celestion first so lower crossover point was preferred)
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Subjective improvement is immediate.
Needs a lot more work to dial everything perfectly, and find the optimal crossover point (frequency and slope)
However, it already leaves the magnesium dome tweeter way behind... (but the beryllium dome will make a come back with a wave guide. I have this plan on the back burner. Who know this time around.)
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Here what it looks like right now:
Please disregard most of the temporary wiring (XLR interconnect from recycled CAT6 cable aren't my usual component choice...)
*Note that the bass bins are tilted back so the distance from both 15" to my ear is about the same as both 15" are in parallel. (to be independent when I upgrade my DSP to 16 channels)
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Crossovers are at 48 Hz, 600 Hz, 4k (all 24 dB/oct for now)
Phase 4, March 2018 (still lot of temporary wiring around)
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Had to try the Beyma CP-22 annular ring before dismantling the room.
-mounted them in a plain 1/2" MDF box for ease of use...
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They must be used at 6 kHz and up, as distortion exceed 0.5% below this point. (Beyma recommends 5 kHz @ 2nd order, but they are being very optimistic. Perhaps they use 1% THD at their reference level. I don’t know, but I prefer 0.5% myself). I initially used 6500 Hz 4th order crossover.
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Distortion profile is very different from the CDX1-1445 mounted on tractrix horn. It has almost no 3rd harmonic, but higher 2nd harmonic content.
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This suggests that the Beyma will match the JMLC subjectively better, as their 3rd harmonic distortion is very similar (and very low.)
The breakup at ~20 kHz seems lower and more controlled than the breakup of the CDX1-1445
Also, the CP22 is about 2 dB more efficient as well.
Note to myself. I really need a better microphone for tweeter measurement. The USB microphone with their 48 kHz internal sampling frequency, are very good for room acoustic measurements, but are quite far from lab measuring equipment for tweeters. The mini DSP, under REW, working on Java plugin is limited to 48 kHz sampling as well. This means that above 10 kHz, measurements are to be taken with a grain of salt.
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Just purchased a Motu 1248 audio interface. This will permit me 192 kHz sampling frequency on the microphone input and analog output.
It’s a well reviewed unit, has respectable specification, an ESS9016 DAC chipset and has 48V mic phantom power too.
Just need to buy a good analog microphone and I'll be set. (good microphones aren't cheap)
I don’t like the SMPS inside the Motu. Perhaps, I’ll have to modify the Motu, opamp inside, which are likely the NE553X variant; not good at all.
Who knows… I've been planning to ditch the MiniDSP 4x10HD for a long time now.
Hopefully the 1248 interface works well as a crossover. (too bad it's only eight channels)
Need to get a good frequency allocator (Thuneau Allocator demo version seems fine, so will start with this one and hope for no lag or crash)
If that doesn't work, I don’t know what I'll do.
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In it's stock form, The Mini DSP 4x10HD used as a DAC (pass through mode) sounds about as good as a $40 DAC on eBay and still, the $40 DAC will be quieter than the 4X10HD
Sorry, Mini DSP fans, they’re really budget priced mediocre products, and about 15 years behind what the Lynx, RME, Motu, Antelope, Apogee currently are. If you think about it, the very music you buy and listen to, are mastered on those studio grade products, and not the Mini DSP’s low-priced offering!
It just makes sense to use studio grade interface to play them back.
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I wish I’d had known this before buying and modding the two Mini DSP 4X10HD...
Initially, the Mini DSP was an eye opener to the Active and DSP world.
But the reality is that after a while, you realize how limited the 4X10HD is and just want to upgrade it.
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Below is the system in late March before I had to dismantle the room.
