New Betahorn
2020 it was time for a new version of the Betahorn.
Main improvement in the midrange, around the crossover (ca 480 Hz).
Due to now 3-way configuration, HF is cleaner at high SPL.
I really like the shape, and the midrange horn’s performance is as good as I can imagine (within the limits of physics) – so these are kept.
The previous version with frontloaded woofer has a steeper acoustical rolloff towards the midrange, the new version omits the basshorn and allows for my preferred time domain behavior, which needs a lower rolloff rate.
An unusually large vent area produces a very open sounding low-bass quality. While looking like an Onken cabinet (see the last picture with cloth cover removed), it is NOT. The ducts are short, which prevents standing wave problems, and provide high acoustical impedance (acoustical damping), for fast and musical bass.
Cabinet shape and dimensions remain (within a few mm) unchanged.
New Betahorns – dark version
This blog shows a special, high quality version of the new Betahorn, using a tightly matched pair of 16 ohms Altec 416 Alnico bass drivers, magnet mass-loading on all drivers, custom color horns, special wiring and crossover parts etc.
Vintage Altec 416 with magnet weight & adapter
416 with weight & support
MF driver with magnet weight
HF unit with magnet weight
Usually I offer to come to the listening room and tune the „crossover“ of my hornloudspeakers to adapt their sound to the room and user system. In this case we went even further and implemented a semi-active version, using solid state monoblocks for the woofers and a single-ended triode amplifier for the mid- and high frequency horns.
This crossover is implemented purely with passive parts, no additional active amplification or buffers are used.
The semi-active c/o allows for better equalisation in this room, which looses a lot of sub-100 Hz pressure due to the set-back corners (but also avoids some nasty LF resonances).
You can see the amplifiers in the rack in the middle between the loudspeakers, tubeamp on top, monoblocks below.
For best performace, the speakers are used without the magnetically attached cloth covers, as shown.
Betahorn with cloth cover removed, amps in the middle
1 Kommentar
Ng Kenneth · 12. August 2026 um 3:53
For many years, I struggled to achieve good sound from my audio system, largely because of the difficult room acoustics that David mentioned. I should also admit that I can be a rather demanding customer. I often challenged David to leave no stone unturned in the pursuit of better sound, and he has always risen to the challenge with patience and determination.
David addressed the room acoustics through a combination of acoustic treatment and passive equalisation incorporated into the crossover and the dedicated bass amplifier that he built for me.
Over time, his involvement grew to encompass much of the rest of my system. He built my phono stage and the power amplifier that drives the mid- and high-frequency sections of the Betahorns, and he is currently working on a preamplifier for me. With the exception of the solid-state bass amplifier, all the electronics David has built for my system are tube based.
Over the years, through his many visits here, David has also become a family friend, in addition to designing and building equipment for me.
With David’s help, I am finally getting the sound I have been striving for and, more importantly, I am simply enjoying the music.
Thank you, David, for your patience, dedication and, above all, your friendship.