Notes from Berlin: The new STEREO M 2 and the magic of point-source audio

The new Wi-Fi streaming speakers the STEREO M 2 sound breathtakingly large despite taking very little space, wowing fans with their wide range of streaming options. Here at Teufel, we want you to hear every microsecond of a saxophone trailing off, every key press on a piano, and every overtone of a synthesizer without having to spend a fortune on a HIFI setup. Our conversation with Massimo from the Teufel Acoustics Department shows just how well we were able to achieve what we set out to do.

A woman places a record into a record player connected to a set of Teufel STEREO M 2 active bookshelf speakers

The STEREO M 2: a pair of active streaming bookshelf speakers with outstanding stereo sound for every music genre as well as TV and gaming.

An even more engaging sound experience

Acoustic engineer Massimo holds the coaxial point-source fused drivers integral to the acoustic concept behind the STEREO M 2
Massimo explains the benefits of the STEREO M 2’s point-source audio.

Teufel Blog: Massimo, I’m sure some readers and fans remember you from the interview about the development of the Cinebar Lux, which has gone on to become very successful. Tell us about your involvement in the development of the STEREO M 2? 

Massimo: With the Stereo M [the previous model], we were starting from a very nice sounding speaker. So we wanted to keep all the good from the old while improving a few aspects and aiming at an even more engaging sound experience for our customers. First, we made simulations and then we built actual prototypes to confirm the results so we knew exactly which components and elements could be improved upon.

Teufel Blog: Tell us in depth about the acoustic concept behind the STEREO M 2

Massimo: STEREO M 2 consists of a stereo pair of high-performance fully active 3-way bookshelf speakers. The high-excursion woofer sits in a vented box, with bass-reflex port placed on the back of the unit. The mid-range driver and tweeter are fused into a coaxial driver. Each channel (woofer, mid-range, tweeter) has its own integrated amplifier and a powerful DSP (Digital Signal Processor) takes care of all audio filters and crossovers.

Natural and life-like reproduction of the original content

Massimo holding a coax fused driver
The coax driver

Teufel Blog: 3-way systems are rare in bookshelf speaker format. What role does the SCA Coaxial Driver, which we also developed in house, play in that?

Massimo: The coaxial driver is a real highlight of the STEREO M 2. As you know, this arrangement places the mid-range driver and tweeter in a concentric position, so that mid and treble frequencies come from the same point source with fully coherent emission: this means that there is no delay between these frequency ranges regardless of listening position. The main advantage is a very accurate, three-dimensional stereo image with a wide sweet spot; additionally, it facilitates particularly natural and life-like reproduction of the original content with minimized coloration.

A close-up of the point-source coax fused drivers

A coaxial driver is more challenging and expensive to produce compared to two separate drivers for mids and highs, but the result is worth the effort. Our in-house developed coaxial driver proved to be very successful in the previous Stereo M so we kept it, but we also optimized the geometry of the cabinet around it: this further improved the clarity and transparency of mid and treble frequencies.

Deep, powerful, and controlled bass

Massimo using speaker measuring equipment on the bass driver of a STEREO M 2
Massimo conducting measurement procedures

Teufel Blog: There were also improvements to the bass drivers. Could you tell us more about what was changed?

Massimo: We improved the motor design and the soft parts to deliver longer excursion with reduced distortion and we optimized the magnetic circuit in order to achieve higher efficiency. The result is deep, powerful and controlled bass.

Teufel Blog: How were you able to optimize the product grilles in such a way that the speakers sound almost exactly the same whether they’re on or off?

Massimo: We worked in close collaboration with Industrial Design department: we really wanted an unobtrusive look for the grille and squeezed its thickness to a bare minimum, reaching the dual goal of a very cohesive appearance and minimal impact on frequency response. The fabric that we use was developed specifically for us with recycled fibers and we put major effort and long testing into achieving perfect acoustic transparency.

Our target users are real music lovers

A STEREO M 2 set in white

Teufel Blog: Speaking of sound, what kind of sound can a customer expect when purchasing a STEREO M 2, and which use cases/music genres is it particularly well suited for? Which types of listeners are the STEREO M 2 perfect for?

Massimo: Every music genre will sound great on the STEREO M 2! The sound is full-bodied yet refined and three-dimensional, so it is suited for any kind of content. Our target users are real music lovers that like to hear every detail and nuance and we want them to enjoy the full emotional potential of their favorite tracks. A convenient equalizer is provided in the app so every listener can customize the sound to their individual taste.

Teufel Blog: It also has improved options for connecting to a TV with the new optical input. Were you surprised by how many customers wanted this option?

Massimo: We provided STEREO M 2 with optical input for more convenient and flexible use: I was not really surprised because using it for TV shows or movies is also a valid use case.

Teufel Blog: Unlike the previous model, the two speakers can now be paired wirelessly. Does that mean both are now active speakers?

Massimo: Yes exactly, the Primary and the Secondary unit are both active speakers with independent power supply and amplifiers. The wireless audio transmission is very convenient, as the speakers can be placed where the user prefers and the only required cable is one power cord for each speaker.

The best audio quality and power efficiency

A speaker being measured in a cluttered audio engineering lab
Every value was measured to precision for the best possible audio

Teufel Blog: What is special about the integrated amplifiers? What kind of power headroom do they have?

Massimo: Each speaker relies on three high-quality integrated amplifiers (woofer, mid-range and tweeter channel) for a total of six amplifiers per stereo pair. Each amplifier circuit is designed to be perfectly matched to the corresponding speaker driver to ensure the best audio quality and power efficiency. Of course the amplifiers have a lot of power headroom so that transients can be reproduced without compromise for excellent rendition of the most dynamic audio tracks.

Teufel Blog: There’s also the newly integrated Teufel Home streaming platform, which makes the STEREO M 2 easier to use in combination with devices people already have at home. What advantages/challenges did that present from an acoustic standpoint?

Massimo: The Teufel Home streaming platform is based on proprietary software and we spent a lot of time integrating and optimizing the required audio features. Among other features, users can now benefit from Aux-in level adjustment (to adapt to different input devices) and a room adaptation equalizer that can be set separately for the Primary and the Secondary unit. All provided with a simple and intuitive user interface inthe smartphone app.

A woman sits in front of a desk with a computer monitor and a set of STEREO M 2 speakers
Stereo M 2: experience the best sound in your home office

All photos: Teufel

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