I developed RF-STOP Faraday Isolation Box in 2019 after determining that using OPTO-DX to optically isolate DAVE from MSCALER was only part of the total isolation solution. RF noise was impinging on DAVE via powerline conduction (AC mains, in-wall & cables), and via open air radiation (up to 5 meters!). I researched and wrote a whitepaper here. Its dated but still worth a read-through.
RF-STOP Faraday Isolation Box was custom developed for me by a well regarded supplier to the mobile phone industry (testing and FCC/CE compliance). I specified rugged welded aluminum construction, RF absorbing liner, optical waveguide for signal isolation, AC filter for power isolation and a functional aesthetic.
The design intent was to be able to enclose MSCALER, Source, Optical networking, OPTO-DX(T) plus all associated power adapters and cabling into the RF-STOP box. The solution performed very well: blocking 99.9999999% of upstream digital RF noise from reaching Dave. For my DIY-savvy customers who were brave enough to trust the science (thanks!), it demonstrated a clear connection between much improved transparency and reduced RF noise.
To make REFERENCE Mojo2 become a true reference, I again utilized RF-STOP Faraday Isolation Box but incorporated the DAC and my latest kit of products to improve transparency further. I also streamlined the signal chain and power isolation. Refer to the functional drawing and my description below. This is the system I will have at the Toronto Audiofest.
PGGB-IT! Offline Processing
PGGB-IT! takes the place of MSCALER to produce 'pre-upsampled' files stored on the user's local server. PGGB's technical attributes are extreme precision (256 bits), maximum taps (all samples in the track) and near perfect noise shaping (200dB lower noise floor than any competition). This produces reconstruction sound quality that's essentially theoretically perfect and surpasses current or next generation hardware upsamplers.
PGGB-IT! processing requires a separate (Windows) computer with a recent CPU, a fast SSD and at least 32GB of RAM.
Audio Signal Path
The music playback signal from a source computer (USB-C port preferred) passes through a USB Filter and connects to the OPTO-USB optical cable and into RF-STOP box's optical waveguide port. The functional drawing details the sequence of connected components inside RF-STOP box to Mojo2 and then back out the waveguide port as analog audio. The specific order of components has been tested as optimal and is important to obtain reference level signal isolation.
The application of RF-STOP EXTREME SE Signal filter on the analog output and external to RF-STOP Box protects against RF noise entering Mojo2 through the galvanic analog interconnects.
Power & Isolation
Many audiophiles already possess expensive AC filters/conditioners, however, IMO, the only way to completely avoid AC Mains RF noise is to utilize a battery + inverter. I recommend combining an ultra-low RF noise topology inverter with an ultra-low electrochemical noise LiFePO4 Lithium Ferro Phosphate (LFP) battery. In my case I used two 12V-120Ah industrial batteries (enough for several days of listening sessions) with a IPSI1200-12-110 inverter from Analytic Systems.
Mojo2 and OPTO-USB receiver (both at 5V) are powered by a single PURE-DC and a 12VAC charger for the lowest possible noise. My reference system would not sound nearly the same without PURE-DC.
RF-STOP Box provides room to enclose all components and cabling as described and shields them from high frequency EMF radiation effects. The further application of DAC-WRAP on Mojo2 will deflect low-frequency magnetic (H) fields as well.
In the final Part 3 of this series, I will have images of my REFERENCE Mojo2 system as I have prepared it for the Toronto AudioFest. I will provide assembly instructions of components, their configuration and all cabling inside RF-STOP Box.