Interlude
(Zwischenspiel)

While I was waiting for CNC routed wood parts for Kierkegaard, which took quite some time, a desire for a quick and easy project kept creeping up.
I wanted something that I could build with my own tools and ideally also with drivers from the basement.
But it had to be a speaker with a nice and smooth off-axis behavior and a dispersion pattern, which is now a bit narrower than that of Kierkegaard.

ZS4

So I took the Seas 5" woofers knowing that I could get away without subs and mated them with the leftover set of Seas NoFerro 900 tweeters. In order to achieve a more uniform off-axis behavior, they are loaded with the small Visaton waveguide WG148R. The combination with the tweeter simply fits in all aspects to the L16RN-SL (H1480) woofers.

But a waveguide in itself does not make a good speaker. As always, the baffle shape also plays a major role.
So I came up with a very simple design in which two chamfered 16mm MDF boards are combined to one minimum baffle with big continuous chamfers to make it as "invisible" as possible to the drivers. With this, the bafflestep assumes text book shape and can easily be equalized.
In addition, the two layers of wood make a nice and heavy “bearing” for the Seas driver and its considerable dynamic forces that develop while it is pumping a lot of air into the environment.

Initially I did not even plan to post this here because it is a rather simple monkey coffin speaker. But I am so happy with the overall sonic result and the simplicity that it deserves a space here.

On the other hand it is not a monkey coffin speaker at all because those exhibit the typical diffraction issues between 2...5KHz, sometimes even over a broader range, which is one contributor to the typical box sound that sticks to the wood.

It would also make an ideal speaker for beginners to get the feet wet.
One set of speakers can be built starting at around 900€/US$ including power amps and two miniDSP 2x4. Actually only one would be required but two DSPs make a tidier cabling in the living room.
On paper and mechanically, the miniDSP PWR-ICE 125 plates would also nicely fit. I haven’t auditioned the amps yet, though.

Update: Meanwhile I was able to audition the miniDSP PWR-ICE 125 DSP/plate amp combo. It was driven from a pre-amplifier wired according to AES48. However, the plate amplifier exhibited residual hum. Besides that there was too much hiss as well and it was lacking clarity. In total a completely disappointing experience.

The Sound:

  • The speakers cannot be localized and the sound floats freely.
  • The center image is well defined and stable during movement of head and upper body.
  • Compared to the previous wide dispersion designs, the sweet spot can actually no longer host two persons. Not for critical listening anyway.
  • Also accurate and equal toe in is more critical than with wider dispersion speakers.
  • The auditory scene is plausible and natural.
  • They nicely render the mic positions but the dispersion is still wide enough to fill the room with sound.
  • There is no listening through a window into the auditory scene and they are not tiring in any way.
  • If there is depth and spaciousness in the recording, there is depth and spaciousness in the playback.
  • Perception of distance: The stage starts at the plane between the speakers and depending on the program material reaches behind them.
  • In total, they fit extremely well the given room acoustics.
  • In short: It is the most complete two way speaker I have ever built.

Setup: 1.8m apart, 1.8m listening distance, >=1m from side walls, 1.7m from front wall, toed in to listen on-axis.


Alternative Design Approach:

It could also be built as a book shelve type of speaker. In this volume the Qt would be around 0.707 without active equalization.

ZS2 ZS1
ZS3

Last updated 13-Apr-2017