Hi guys, OK, here is where we are at right now. Your feedback and level of interest will help me to decide which way to go:
USB is not a feasible option to offer as part of this digital input offering. (I do plan to offer it with our own DAC at which time its design is complete however).
SP-DIF via RCA and/or BNC and also AES/EBU are not a problem.
The best way to connect USB would be via ANY outboard USB-RCA(SP-DIF) converter.
THE REASON I say this is because I am considering contracting a design that will keep jitter levels to the 5ps level, thanks to reclocking AT the digital input interface, rather than just relying on the input receiver to handle clock data. This module will be configurable for both Sony 5400ES and Oppo BDP-83/83SE (to start with) and will output I2S data, allowing us to implement this in virtually ANY player in the future.
I plan to offer a physical toggle or selector swith on the rear of the unit that will allow you to select between digital input formats: i.e. RCA, BNC, AES/EBU, optical, etc.
Right now, I estimate the cost of this upgrade - WITH custom reclocking circuit onboard digital input circuit - to be in the $750 range, including upgrade module, installed in your player. If we were just to use a digital input receiver (jitter in the 200ps range) to reclock the data, then I would expect the cost to be less than $500.
To be clear, the re-clocking of this digital input circuit is NOT the same as the player's master clock. The master clock in the unit is going to be different, because the player is decoding PCM, DSD (SACD), Blue-Ray (Oppo), etc. The clock in this input will ONLY be treating the digital signal coming into the player, to feed the player's DAC and our analog stage.
The REASON that this clocking circuit is important, is because the digital input circuit will be virtually immune to jitter levels entering the player. The use of digital processing and buffering will allow for this to happen. And, you can also use any external USB-SPDIF converter without worrying about the quality of sound due to the shortcomings of the USB interface.
I had the pleasure of hearing a DAC design that Ted Smith - moderator of other forums on the net (not the person whom I am contracting with) - designed as a labor of love. The designed involved a FULLY DISCRETE DAC - i.e. not a chip, but built from FIRST PRINCIPLES with discrete components. What I found interesting however, was that he used a VERY inexpensive USB-SPDIF converter to send music from his laptop to his DAC. We listened to hi-rez and redbook formats and the design was SO GOOD that the difference between Redbook and hi-rez was startling. When asked about the USB interface, his reply was that because the data was buffered and clocked internal to the DAC, external jitter was NOT an issue. The overall sound of this design was simply staggering and I do hope that Ted pursues it on a commercial basis. If he does however, it will NOT be cheap!!!
I know there is much debate on this subject of clocking, digital interfaces and jitter. From a design standpoint, I want to express our approach and also price as it relates to our cost.
Final question then, by a 'show of hands', how many people are interested? We will likely offer a pre-order special at a discounted price.
I am poised to proceed, but the investment is non-trivial. I want to do it RIGHT and I need to know that there is sufficient demand for us to proceed in this particular direction.
Thanks for reading.
Sincerely,
Dan W.
President,
ModWright Instruments Inc.
360.247.6688
