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In the Forum: Horn-Loaded Speakers
In the Thread: The absolutely “best” material for horns construction.

Post Subject: Low power SET is not a problem.Posted by JLH on: 8/19/2009

Low power set should not be a problem. The Unity was fine with SET amplifiers, so the Synergy should be no different, if not better. The Synergy horn is different than the original Unity horn. There are some very specific improvements in the Synergy horn, so significant that another patent covers it. See following link for Synergy horn patent application:

http://www.wipo.int/pctdb/en/fetch.jsp?LANG=ENG&DBSELECT=PCT&SERVER_TYPE=19-10&SORT=41270106-KEY&TYPE_FIELD=256&IDB=0&IDOC=1468907&C=10&ELEMENT_SET=B&RESULT=2&TOTAL=5&START=1&DISP=25&FORM=SEP-0/HITNUM,B-ENG,DP,MC,AN,PA,ABSUM-ENG&SEARCH_IA=US2006022032&QUERY=%28IN%2fdanley+AND+IN%2fthomas%29

Sorry for the long link – just click or copy and paste into your internet address bar.

Anyway, the thing that sets the Synergy apart from the Unity is its phase coherence. This is achieved through some very specific design steps.

1.) The mid or low frequency driver(s) that tap into the horn are electrically bandwidth limited (crossover) below the point where you get the first high frequency cancellation notch. The cancellation notch is created when the distance from the tap point to the apex (compression driver voice coil) is equal to half a wavelength. Some clarification is needed here. This is really not an actual physical distance, but an acoustical distance. This is because the apparent acoustic center of the compression driver and the mids/low drivers do not occur at the voice coil. However, it is not too hard to figure this out with the help of AkAbak simulation software.

2.) The cross sectional area where the mids/lows tap into the horn is such that the circumference is equal to or less than one wavelength of the highest frequency you want it to produce. For example, if your mids tap into the horn where the cross sectional area is 93.5 sq cm, then you would not want to have it produce anything above 1KHz.

3.) The tap point of the mids/lows must have a local expansion rate equal to, or lower than the lowest frequency to be produced. For example, if you want the mid to produce down to 300Hz, then the flare rate at the tap point looking forward toward the mouth must look like a 300Hz or lower flare rate.

4.) The ports or ducts that the mids/lows tap into are not cylindrical in shape. Either they appear as conical, or as a counter bore shape. They are described as being frustoconical in the patent application. This greatly reduces the acoustical impedance of the ports, so you can use a smaller diameter port without running into compression problems. Long and large diameter ports decrease bandwidth and SPL which are things we are trying to avoid.

Overall, the Synergy design is a substantial leap in performance over a Unity. I have played around with a Unity model a few times. I never came up with a completed project. However, with the new design criteria now available from the Synergy patent I am more inclined to try it again. Even my quick and dirty attempt had some sound qualities that were very inviting. The point source and constant directivity behavior was very pleasing. It did not have any of the problems associated with multiple horns such as lobbing and narrowing directivity.

Inclosing, I heard the Danley SH-50 at a dealer in Pennsylvania. It was shocking how coherent it was. The intelligibility and how it was able to flesh out details and separate all the sounds was very surprising. Each sound came from a stable and correct position from within the sound stage. I might say it sounded almost too hi-fi to me. Of course personal preference will play into this. However, I can see people using this speaker in their HT setups with excellent results.

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