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AfterDark. Project ClayX Giesemann OCXO Trifecta Mini SE for SoTM sMB-Q370 Audio Grade Motherboard

Phase Noise and Allan Derivation Measurement By Symmetricom 5125A Included
Output Frequency
Grade vs Phase Noise@10Hz

The new development of Giesemann OCXO Trifecta Mini SE for SoTM sMB-Q370 Audio Grade Motherboard


This version is designed along with customer who is recently purchase the SoTM sMB-Q370 Motherboard for Music Server. Since Q370 is requires a specific frequency to work. He contact AfterDark. and see if we design and develop a Giesemann OCXO Sync Clock Module which is tiny in size to optimises the motherboard with specific clock frequency and output the clock signal to sync with both CPU at motherboard and LAN port for SoTM sMB-Q370 Audio Grade Motherboard.


There is two clock inputs on the SoTM sMB-Q370 Audio Grade Motherboard. One for CPU and One for LAN port



We know thare are customer using AfterDark. Giesemann OCXO Master Clock. They are very keen on improving the existing device with external clock with Giesemann OCXO Reference 10M Master Clock. 





The UF.L clock connector for 25MHz is located near the LAN port at the back



The UF.L 24MHz connector for CPU is located near the big S heatsink




The basic clock input design is not bad, but the biggest advantage and difference of the Q370 is that a clock option is provided so that external clock can be used.


If the external clock option is selected for the Q370, the Q370 runs with the external clock instead of the board clock. When the Giesemann Trifecta Mini is installed, the Q370 board operates with a much higher precision clock and noise is reduced. In addition, when using Giesemann Trifecta Mini, the music server will operates with an external master clock input of 10MHz. In other words, Giesemann Trifecta Mini must be installed on the Q370 to enjoy the full potential of the Q370 board.




What is the design concept of Giesemann OCXO Trifecta Mini?

  • The outputs signal will be in Square Wave, 75 Ohms with isolated with 3 outputs BNC Connectors.
  • Each of the outputs can be adjusted and factory preset to various frequency
  • The chassis is rigid, heavy weighted and fine tuned with Carbon Fiber for EMI protection and ensure highest stability of OCXO inside
  • Accepting external audiophiles LPS (Linear Power Supply) for demanding applications and optimised for OCXO Master Clock
  • The dimension will be the same as Giesemann OCXO Single Output Version. 
  • The color of chassis is in black color
  • Three metal covers for PCI slot with BNC Input Connector with connecting IPEX Cable will be provide for direct input on the UF.L connector at the Q370 motherboard 
    1. PCI Metal Backplate for 24MHz Input (CPU)
    2. PCI Metal Backplate for 25Mhz Input (LAN)
    3. PCI Metal Backplate for 25MHz Input  (AfterDark. Giesemann X1 SFP NIC SE Card) or 1 PCI Metal Backplate with 3 input BNC connectors
  • Plug and Play compatibilty for SoTM sMB-Q370 customers 




What is the DC input required for Giesemann OCXO Trifecta Mini

  • Accepting external LPS with 15V DC at 2A
  • The external DC plug standard is 2.1mm/5.5mm. 


What is the special when we design the power section inside the Giesemann OCXO Trifecta  Mini?

  • By using LT3045s in parallel to spread the current, it is designed for very high PSRR.
  • Trifecta Mini will equiped with Four LT3045 in parallels to ensure Ultra High PSRR (Power Supply Rejection Ratio), this ensure the high ability to remove power supply ripple, if any, on the input external power supply 
  • This ensure highest Audio performance on OCXO with lowest derivation on Phase Noise and Allan Derivation 







image.thumb.jpeg.01516b9626a7c351e366dfccca02891a.jpegAfterDark. Giesemann X1 SFP NIC SE for SoTM sMB-Q370

Why it is important to use external Master Clock for SoTM Q370 Motherboard?

  • This is a night and day difference, and Master Clock unlock the full potential on Motherboard 
  • Giesemann Clock is the heart of any digital audio system. It sets the tempo of all the digital pieces of audio equipment in a audiophile system.
  • Based on ultra high precision, the Giesemann clock OCXO is extreme low in phase noise in 1Hz and 10Hz interval. It brings the pivotal timing accuracy that enable DAC, Music Streamer and any audiophile network switch products equipped with a SYNC input of Master Clock to function optimally.
  • sMB-Q370 is a computer board, so the hardware design can have a big impact on sound quality. That's the reason SoTM released the main board. Existing computer main boards are speed-oriented products, so the selection of components, circuit pattern design, clock operation, and power supply are strictly tailored to specifications and functions. However, for audio devices, priority should be given to design related to sound quality rather than simple operations or functions. Noise reduction, cleaner power supply, and clock design suitable for audio equipment are design points that can improve sound quality rather than faster processing and new functions. SoTM's various products and accessories have already proven such a difference in sound quality, and the accumulated results have been tightly integrated into the Q370.

  • Audiophiles asked SoTM directly about the advantages and differences of the special design of the motherboard Q370. I heard a direct explanation of what the Q370 is different from a general computer board and what the difference is in terms of sound quality.




What is the range of Giesemann OCXO grade can be choose?

  • All grades of Giesemann OCXO from Prince to Emperor Giesemann EVA can be made to order for customers


What is the specification to determined the Quality of OCXO?

  • They can be graded by Phase Noise when compared the measurement result on both 1Hz / 10Hz intervals.
  • Phase noise: -119 to -113 dBc / Hz or lower at 1 Hz offset (Grades) -137 dBc / Hz or lower at 10 Hz offset


GRADE Phase Noise@ 10Hz Phase Noise@ 1Hz
PRINCE -131 -100
QUEEN -132 -103
KING -134 -107
Emperor Signature  -138 -110
Emperor CROWN -140 -113
Emperor DOUBLE CROWN -141 -117
Emperor TRIPLE CROWN -142 -118
Emperor Giesemann -143 -120
Emperor Giesemann EVA -145 -121


Allan variance short-term stability reference value

[Emperor Giesemann EVA]TAU = 1sec 2.50E-13 or less(0.00025ppb / s)

[Emperor Giesemann] TAU = 1sec 2.78E-13 or less(0.00028ppb / s)
[Emperor Triple Crown] TAU = 1sec 3.8E-13 or less(0.00038ppb / s)





What is the summery of adjustable frequencies?

  • 100Mhz, 50Mhz, 48Mhz, 30Mhz, 25Mhz, 24Mhz, 8Mhz, 4Mhz, 33.8688Mhz,
  • 49.152Mhz, 24.576Mhz, 12.288Mhz, 90.3168Mhz, 45.1584Mhz,
  • Word Clock: 192kHz, 176.4kHz, 96kHz, 88.2kHz, 48kHz, 44.1kHz
  • Reference Clock: 10M Master Clock 


What is the standard frequency setting for SoTM sMB-Q370 customers?

  • Output 1: 24Mhz (CPU)
  • Output 2: 25Mhz (LAN SFP NIC Controller)
  • Output 3: 25Mhz (USB CARD)


The miniminst design of Giesemann OCXO Trifecta Mini SE Edition for Q370 will work plug and play. 



A demostration on AfterDark. Project ClayX Gisesemann OCXO 10M Reference Master Clock


Giesemann OCXO Features 

The product uses the selected audio grade OCXO, and through long-term calibration to select and install equipment with excellent stability.

  • OCXO that employs with qualitative measure equipment.
  • OCXO is enclosed and covered with Dynamat Extreme Corporation (Made in USA) which is used to stabilize and minimize heat separation,  addition EMI material from KEMET EMI Shielding is placed on top of OCXO,  the outer layer is covered with real leather to isolate the heat factors for maximizing OCXO performance . 
  • Alu material + Carbon Fiber material front and backplate, solid anti-vibration. In addition, due to the thickness used, 3mm / 6mm Carbon Fiber material material with plate can provide solid EMI/ magnetic coverage.
  • Advanced instrument Symmetricom 5125A calibrated with plotted characteristics. The phase noise, and Allen Derivation defines different grades of the OCXO. 
  • Audio Note Silver Solder
  • Duelund AC0.4 Silver Premium Audio Cable (Silver in Cotton / Oil impregnated) (Handmade in Denmark)
  • Ultra High Quality Large Factor 5151 SC Cut OCXO, very low phase noise and frequency stability compared to others small size OCXO specification 
  • SC Cut refers to stress compensated (SC) cut crystal resonators, which is more advance on performance of Frequency Vs Temperature changes, longer Crystal Aging. The pro is expensive to made and size is larger then normal OCXO. 
  • Then Large Factor size 5151 is around 5cm x 5cm dimension vs small factor 3cm x 2cm, 2 times bigger with better phase noise performances. 
  • OCXO are available in tailor made on various audio frequencies on special request. 


Level selection value
The OCXO installed in the product can calibrate the products used in industrial equipment for a long time, and use equipment with good characteristics. In order to optimally select the audio clock, we comprehensively evaluate with Symmetricom Flagship 5125A to analysis the phase noise characteristics and short-term stability (Allen dispersion) that can be determinate the OCXO grading accordingly.

The OCXO installed in this product uses a stable OCXO unit that has been calibrated for several months. In order to make the best choice of OCXO. We are conducting a comprehensive evaluation of phase noise characteristics and short-term stability (Allen dispersion) during detailed inspection. 


The final product will final measured and fine tuned with Keysight 53220A with reference to Atomic Clock , GPSDO. 




The Trifecta Mini of Giesemann OCXO Modules is enclosed by Carbon Fiber AudiophileMAT in 3mm








Type: OCXO Clock

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