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Single Speaker Stereo or SSS
single speaker stereo concept.png

     Speaker working principle is visually explained in the above picture. The way connection is done internally in Baffless SSS is in  Pic.1. This is kind of delta connection instead of usual star connection. This is because amplifiers used are floating load amplifiers and star connection will not work.  This connection is more complicated than it looks. It's because the amplifiers used are with varying output impedance vs frequency. Resistor in series with the front driver is used to make about equal output from all drivers for center panned signal. So the speakers acts as monopole source with equal output front/left/right. The sound is spread more evenly across the room. Power response is a little better, because highs and lows  are about the same at center position and extreme left and right positions. 

   Connection in Pic.1 gives so called beam steering effect. In addition to that MID/SIDE stereo coding is used to increase SIDE signal gain. It is adjustable because it depends on room acoustic and dimensions. But the idea is to increase SIDE signal which is coming from side speakers and is bounced back from the walls. It has to travel longer distance and is absorbed a little bit by the wall. So increased SIDE signal has very positive effect on listening experience. Also this increase in SIDE signal is done with different magnitude for different frequencies. So the complete scheme is quite complex. 




Pic.1 Connection method used

    Amplifiers used in this speaker are Baffless amplifiers. They are separate topic as they are very unique. DAC and amplifier integrated into one board guaranties the end performance to be perfect. If in example the user uses very good DAC with 120dB performance and an Amp with the same performance it is not guarantied that the end performance will be 120dB. There are many things that can go wrong. Ground loops, EMI noise, interconnections an so. Noise floor of Baffless amplifier is below 120dB, THD in 0,000x range.(measurement equipment is a limiting factor for now to measure exactly). Amplifier is universal. It has integrated Sabre DAC and is fully galvanically isolated from digital source and standby power source.  Clipping and DC protections, auto power on/off. Click free on/off. Output transistors are 900W rated for short term power, no electrical isolation pads required. Easy reliable mounting. Amp designed to be reliable as reliable can be.  Can be configured as voltage amp, current amp or mixed mode amp. In this speaker they are configured as mixed mode amps. So voltage for low frequencies and current for high frequencies. This is done to get lower distortions from dynamic loudspeakers. This gives more open sound, true-life like sound.  Distortions in loudspeaker drivers are vastly greater the distortions of amplifiers itself so it is wise to take them down with the help of amplifier.  

Pic.2 Current drive vs voltage drive


Pic.3 Baffless amplifier

     Speaker has three streaming options. It is DLNA, Airplay and Roon. The Airplay streaming was the first in development process because it is just works from apple devices. It is simple to use, reliable and no setup needed. In other words user friendly. 

     The second streaming option is Roon app. This is because it is of higher quality than Airplay. Roon uses it's own developed RAAT protocol for streaming. It supports higher sample rate and bit depth compared to Airplay's CD quality 44,1kHz 16Bit quality. It works with audio backend clock source. Sends data when needed. So can work without any resampling theoretically. 

     The third option for streaming was chosen DLNA. Because Roon is very good, but expensive App. And android users are left without Airplay. So DLNA is for android users mainly.  

     Digital part is developed with care. Every chain of digital signal transmission is checked to make sure everything is correct. Many people think that digital part is always correct. You stream 96kHz and 24bit and you get exactly that into DAC. No it's not the case very often. There are many processes involved in between and many things can go wrong. Settings can be not optimal. The code can have bugs. I test digital signal by looking at the spectrum and making long term peak hold metering. Pic. 4, Pic.5. 

Also i have done audio file for test purposes. Every sample holds the same bits. So it is easy to see the correctness of the  bits with the scope on I2S line at DAC side. With the scope i can see actual word length. Is it 16/24/or 32 bits. See most and least significant bits and how they behave. And see if there are any problems. Baffless amplifier is fully DC coupled and can be used as adjustable DC voltage or current source with this audio file.


    Pic.4 Airplay digital stream 1khz noise floor peak hold mode


    Pic.5 Roon digital stream 1khz noise floor peak hold mode

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