Mijostyn wrote: "there is a compromise in a two way horn system that is difficult to get around. You either have to run a woofer up into the midrange or make a very large horn to get down to where most woofers do well."
Done right, I don’t think there is any compromise to performance.
I’d like to address two myths about prosound-type woofers, such as might be found in a horn system:
First, people mistakenly think big woofers are inherently "slow" because of the cone size, when in fact a good prosound woofer has such a powerful motor that its motor-strength-to-moving-mass ratio is competitive with, and often superior to, small high-end midwoofers (5" Scan-Speak Revelator and Illuminators, for example). The 10" prosound woofer I’m working with at the moment has a motor-strength-to-moving-mass ratio competitive with a 5" Scan-Speak mid.
Second, people think a big cone cannot have a smooth response. The truth is that the accordion surrounds on prosound woofers do a better job of damping cone breakup than half-roll surrounds do, such that plus or minus 1 dB before EQ is possible up to the crossover region on a studio-quality pro woofer, and without nasty spikes in the response north of the crossover region. (For example, look at the Eminence Kappalite 3015 and imagine crossing it over a 1 kHz... the woofer Peter Noerbaek uses in the speaker linked in his post is in that same ballpark).
And here are some of the advantages of a using a good prosound woofer in a horn system:
- Because the large cone has a relatively narrow pattern in the crossover region, if the speaker designer so chooses, it is easy to match the woofer’s pattern with the horn’s in the crossover region. This is virtually impossible to accomplish with cones ’n’ domes. The result is, a good horn hybrid speaker (meaning horn + direct radiator woofer) can have an audibly seamless crossover.
- The relatively narrow pattern of a big woofer + horn system means that less off-axis energy is going into early reflections. According to researcher David Griesinger, early reflections are the ones most detrimental to clarity, so this characteristic of horn systems promotes clarity.
- If the designer chooses to use a constant-directivity horn, the reflections will have nearly the same spectral balance as the first-arrival sound, which promotes natural timbre and freedom from listening fatigue.
- Prosound type drivers are free from compression effects in a home audio application, which is not true of most moderate-efficiency high-end drivers. Musicians use dynamic contrast to convey emotion, so a good horn speaker conveys the emotion in the music better than most conventional speakers.
- Many horn speakers are compatible with specialty tube amps, such as Output TransformerLess (OTL) and Single-Ended Triode (SET) types.
- Set up properly, you can actually get a wider sweet spot with a good horn system than with any other type I am aware of.
The inevitable tradeoffs are large enclosures (lower WAF) and less low-end extension than a comparably-sized speaker of lower efficiency.
For those who think modern horn systems still have coloration issues, but are open-minded enough to do a little reading, you might google "JBL M2" or "Dutch & Dutch 8c". The speakers Peter Noerbaek linked to are essentially a hot-rodded version of the M2, and imo they are magnificent.
Duke
