400v PS board test

 Project Log: Custom X-OnWall High-Output Surround Satellites

Overview & System Application

• Role: Front Height & Rear Surround Channels (Multi-Channel Matrix Tracking)
• Cabinet Profile: Compact 0.2 cubic foot acoustic suspension (sealed) enclosures.
• Processor Configuration: Crossed over inside the AVR/Pre-amp at "Small" (80 Hz High-Pass).

By offloading all subsonic bass current below 80 Hz to the active subwoofer grid, these compact cabinets stay completely free of internal pressure distortion. This system has been replicated multiple times using various high-efficiency on-hand drivers, consistently outperforming commercial surround options like the stock Klipsch R-41SA or vintage Carver satellites.

---

The 2nd-Order Passive Crossover Blueprint

Because these modules operate strictly as ambient and height effect surrounds, the signal path was kept fast, minimal, and phase-consistent using a classic 2nd-order electrical layout.

text

                  +---+ 4µF Cap       
Hot (+) ----o-----|   |-------o----------------------- Tweeter (+) [1TD1-8]

            |     +---+       |       
            |                 |                   
            |               [===] 1mH             
            |               [===] Shunt          

            |                 |                   
            |               GND (-)             
            |
            |     +-----+ 0.80mH Coil
            o-----| mmm |-----o------------------------ Woofer (+) [6MB200-4]
                  +-----+     |
                              |
                            +---+ 15µF 

                            |   | Shunt
                            +---+
                              |
                            GND (-)

Use code with caution.

1. Woofer Low-Pass Section

• Driver: PRV Audio 6MB200-4 (6-inch Pro-Sound Mid-Bass, 4-Ohm nominal)
• Network Topology: 2nd-Order Low-Pass (0.80 mH series inductor + 15 µF shunt capacitor)
• Acoustic Function: On a fast 4-Ohm pro-sound driver, this combination shapes a smooth electrical roll-off starting between 1,500 Hz and 1,600 Hz. It effectively shelves down the 6-inch paper cone's natural upper-midrange beaming, preserving raw transient speed right up to the tweeter hand-off.

2. Tweeter High-Pass Section

• Driver: GRS 1TD1-8 (1-inch Directivity Controlled Dome, 8-Ohm nominal)
• Network Topology: 2nd-Order High-Pass (4 µF series capacitor + 1 mH shunt inductor to ground)
• Acoustic Function: On an 8-Ohm load, the 4 µF and 1 mH values initiate an 12 dB/Octave electrical high-pass slope near 2,500 Hz. This guards the 1-inch dome against voice-coil heat from lower frequencies while seamlessly blending into the acoustic decay of the PRV woofer.

---

Why this DIY Approach Destroys the Klipsch R-41SA

Mass-market surround satellites like the Klipsch R-41SA are heavily compromised by cheap parts and restrictive tuning goals:

• The Commercial Bottleneck: Box-store surrounds typically use tiny, low-efficiency woofers and high-order crossovers jammed with cheap electrolytic capacitors and thin iron-core coils. This causes high power compression and a sterile, localized "flashlight" beam of sound.
• The DIY Advantage: Pairing the high sensitivity of a 4-Ohm pro-sound driver (PRV 6MB200) with a smooth, open-sounding 8-Ohm hifi dome (1TD1-8) yields massive dynamic headroom. The deliberate asymmetric overlap—where the woofer naturally starts dropping early around 1.6 kHz and the tweeter gently glides in past 2.5 kHz—sums linearly in the room without requiring complex, power-robbing passive notch filters.

The resulting soundstage doesn't draw attention to the speaker box itself. Instead, it creates an explosive, wide-dispersion ambient field that perfectly keeps pace with high-output main towers during dense cinematic surround pans.

---