Kitchen Doors and Paper Horns, Part 2

Kitchen Doors and Paper Horns, Part 2

Written by Sebastian Schlager

Around 2006, I discovered that digital technology could be a game changer for audio reproduction. Getting full control over the system and avoiding the analog crossover was for me a big step in the right direction, for better sound. Much later, when computer CPU power became much stronger, I embraced DRC software (digital room correction) that builds its algorithms based upon studies of the human psychoacoustics. While DRC cannot make an acoustically bad room sound good, it can minimize unfavorable effects of a room’s acoustics.

Playing in active mode via Behringer DCX 2496 made it pretty easy to match the horns, with respect to sensitivity. Time aligning them and here and there, bring some equalizing into play, I started enjoying my efforts.

First horn iteration, with green tapped horns, made out of scrap wood

I now knew that this was, for me, the way to go. Despite of some sonic issues here and there (mainly in the integration between the tapped horn subs and upper bass and a bit of graininess in the treble, due to diaphragm breakup), it was evident that this system had a grip on the music in a very different manner than normal box speakers. Dynamic and fast transient response, check. Transparent and big “see through” soundstage, check. Uncompressed at high SPL, check.

Next I added a bullet tweeter, which later was swapped for a compression tweeter, of course with own paper tractrix horn mounted. Biggest (no pun intended) improvement was the addition of a 3000 liter front loaded bass horn, instead of the tapped horns, incorporating 4 Fane Colussus 15XB drivers, loading from 24 hz. I did not exactly need more bass headroom, as the monster bass horn theoretically could reach +140 dB, but as all audiophiles know, the room will mess up the response, particularly in the bass region.

Wanting a more even in-room bass response, I took the Earl Geddes multiple subwoofer principle in use. Adding two 500 liter front loaded horns, each with a 15” driver, to each side of the listening position, did the trick.

The system:

Three cubic meters bass horn with 4 x 15″ Fane Colossus XB drivers, operating from 24-100 hz. A Behringer Inuke 6000DSP with 2 x 2000w /4 ohm powers it. This hangs from the ceiling, to free up ground space.

Upper bass, from 100-500 Hz is loaded with Electro Voice EVM 15L driver. Amp is Behringer Inuke 1000DSP.

Midrange is a tractrix 190 Hz paper horn with JBL 2445, 2” exit compression driver from 500-5000 Hz. Amp is NAD 7100.

Tweeter is a tractrix 1200 Hz paper horn with Celestion CDX1-1747, 1” exit compression driver from 5 – 20 KHz. Amp is Onkyo TV960.

A MiniDSP Open-DRC-DA8 function as the heart of the system. Basic driver equalizing, x-over all LR 48 dB, driver time alignment and pre-amp.

A Behringer DCX 2496 handles the subwoofers. Coupled with the MiniDSP it gives me greater flexibility. System efficiency around 110db/1w.

All cables and interconnects are DIY.

As you see, I don’t rely on fancy cables or so called high-end gear. This hardware is pretty basic. It measures and sounds well and is affordable.

I play my music through a laptop, which is connected to an USB/ SPDIF converter, before entering the MiniDSP. From the laptop, I run a DRC (digital room correction) convolution filter, which takes care of the frequency amplitude and time domain, through FIR filters.

My music is stored on external hard disc drives, and occasionally I use streaming. If I want to play CD’s I use the laptop’s built in drive.

A sound system of this size begs for a dedicated listening room, in fact all serious sound systems do. I knew beforehand, that all this gear could not be fitted into a normal living room as WAF is close to zero, so luckily for me, all my toying around, has taken place in my garage. With no limitations, in regards of décor or other impracticalities, I have free hands.

The listening room has been treated with membrane bass absorbers, placed in the corners behind the system. Three big panels 60 x 240 cm, made from double layer plasterboards combined with Rockwool bats (mineral wool) is placed under the ceiling, over the listening position. The sidewalls are also treated with 5 cm (2”) Rockwool bats. 10 cm of Rockwool bats and then an outer layer of acoustic absorber panels from Rockfon, cover the back wall. Behind the listening position a DIY skyline diffuser is mounted, for better dispersion of frequencies over 700 Hz.

The sound:

The sad truth is that many audio people continue to believe in magic drivers and capacitors – magic cabinet materials and think/hope that is all that is required. I strongly beg to differ. As a general rule and giving the nature of horns, I believe they are much more sensitive, so to speak, with regard to their implementation. In fact, it is all about implementation. Nobody is going to walk in and just by listening to a system, say “Oh these sound like TAD compression drivers”, or “These sound like Altec 288’s”. Not going to happen. What makes more difference than driver selection, expensive front end, etc. is implementation. Good drivers are of course needed, but they don’t have to cost thousands of dollars per unit or to be a certain vintage model, impossible to obtain.

That said, horn profiles, size, crossover frequencies, slopes, integration with the room, room treatment, FIR or IIR filters, individual horn bandwidth, physical distance between the horns for best integration, time alignment, front gear (regarding noise), all are at play. Poorly done, and the sound will suffer. Often to a degree, which will back up the sonic bashing that has been the Achilles heel of horns for so many years. With noisy gear, you will raise the noise floor to an obscene level of hiss and hum. This takes time and patience, but THIS is the important stuff. You’ll need to measure, adjust, listen, repeat. With so many pitfalls, it takes a lot more effort by the user to get a good result sound-wise with horns, than  with “normal”speakers. However, get it right, and horns offer a dramatic increase in speed, dynamic capability, image size, transient response and presence, with harmonic distortion less than one quarter of the value found in normal direct radiator systems. Moreover, most direct radiators severely compress dynamic contrasts, reduce image size and sound fatigued and almost anemic.

I want my music to be created with the drama and intensity that is instantly recognizable to anybody who has ever heard or been moved by live music. That’s a key element that brings me closer to the real event. I don’t want the speakers to do the talking, I want the people and instruments captured on the recording, to reach out at touch me emotionally.

After a long audio journey and many hours spent on studying and building my horn system, I can finally sit back, relax and enjoy the efforts.

So, what is it I hear, that sets these speakers apart, from anything else I have owned or heard elsewhere—whether at Munich High End or in private audiophile homes? It is not just what I hear, but also what I feel, when I listen to them play.

With this system, you feel the music, you become part of the music, and the music becomes part of you. The full-range phase coherent wave front of the horns (remember, I use minimum phase FIR filters) produces a solid image and lifelike, transparent presentation. The sound is crystal clear and even the tiniest details will be revealed, almost as though hearing through acoustic binoculars. They present the music with the correct instrumental texture, tonality and harmonics. The natural, communicative quality and realism these speakers are capable of are immediately apparent, to anybody who has listened to them. In short, they sound very effortless and real. No matter of how high up you crank them, they will hold their ground and poise —and your ears will give up long before the speakers, believe me.

Due to the horns’ inherent benefits of low distortion, high efficiency, fast and accurate transient response, and wide dynamic range, these loudspeakers provide a pure, lifelike musical presentation, a more organic and natural recreation of the acoustic event. As a result, each different musical selection is portrayed with its own character and life, not that of the playback system. The performers will be there, in the room, performing for you. With realistic speed and impact, even at low level, the sound is never veiled or compressed and one easily hears, in comparison, how constrained most speakers really are and how much distance they introduce between the performance and the listener. With this expressive nature, they are the key to unlock the energy and emotions of a recording.

Take the bass, for example. There’s none of the pounding weight that is typical of hi-fi low frequencies, especially from dedicated subwoofers; an earth-bound rolling thunder. This horn bass floats and envelops full of texture and layered harmonics, rather than slabs of sound that slam you in the chest. The latter can be fun for a while, just for the visceral impact, but in the long run, it becomes tiresome and uninvolving.

Playing guitar in a local band and being in the rehearsal room, I can feel the visceral impact of the kick drum. Having an upper bass horn that covers the power range, around 100 to 300 Hz, gives me the same sensation, when hearing a well-recorded drum kit. Take the tight dry sound from a real snare drum, which is almost explosive. Here the fundamental tone is easily captured by the upper bass horn while the midrange horn integrates the upper harmonics, to create a near perfect illusion of the real thing. No normal speakers can re-create the same sonic illusion, in regards to, dynamics, speed and impact, not forgetting lifelike SPL, period.

Hi-hats and crash cymbals sound very real with true resolution. Without dynamic compression and having fast transient response, you get the full energy spectrum of the complex harmonic structure, that reveals what kind of cymbal it is, how hard it is struck, and where.

Female singers like Diana Krall or Eva Cassidy sounds sweet and delicate. Then take Gordon Goodwin’s Big Phat Band, and there’s nothing sweet or delicate about the manner in which these speakers recreates the blast of a trumpet, the wail of a sax, or the sound of wooden sticks on rim shots. The timbre and transient attack of instruments is unmistakably real.

You want to be transported back to a live concert venue? Give Al Jarreau – Live In London 1985 a spin and you feel that you are among the audience looking at the stage, with a big sound picture in front of you.

Delivered through this system, with some SPL muscle behind, not only the band is having a great time.

More into electro pop, then Yello – Planet Dada will deliver plumping synth bass that will rattle the room. On top, all kinds of digital blips and odd noises will be carved out in the soundstage.

Put on a big symphony orchestra, which blasts into a full-throated climax. The power, level and dynamic capabilities are physical in terms of live presence and musical impact. You never lose the sense, that this really is a lot of people working together, to move a lot of air.

These speakers don’t just attract attention, they grab it and hold it. Overall, this horn system has a very natural timbre, with immediacy and delicacy in spades. Combined with the speaker’s ability, to resolve the smallest dynamic shifts in musical notes, as well as to cover the widest dynamic leaps, it allows this setup to project music, in a way, which is almost intoxicating and very enjoyable.

The Dannebrog Horn System and the proud owner!
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