Let's address some issues in various recent posts:
Firmware
Regarding firmware, please raise a ticket via our support platform if there are any issues. Our staff might make beta releases available on an individual basis at their discretion. When a new stable release is available it will be available at the official iFi audio site.
Filters
We provide the option to operate without any filter and also to upsample to DSD without applying any digital filter. This bitperfect mode is in effect the same as the non-oversampling mode. It causes slight very high FR roll-off and the BP+ mode corrects this via an analogue filter.
We also offer a choice of digital filters for PCM (and within some limits DSD) playback, namely:
- Gibbs Transient Optimised aka. the GTO - it minimises the Gibbs phenomenon causing time-domain distortion, more about this one we'll reveal shortly.
- Apodising - this one is said to correct some problems in digital recordings and has many fans
- Transient Aligned - this one a very large number of taps
As upconversion to DSD uses first oversampling to 705.4/768kHz, all filter options apply unchanged to DSD upsampling.
The main exception is is with DSD inputs. DSD is processed either as bitperfect signal only (no filter choice) or upsampled to DSD512/1024. In the latter case there is no 'bitperfect' filter option (upsampled DSD must use a digital filter).
Our default recommendation for filter is now our new GTO, which we feel offers the best balance between the various requirements of suppressing unwanted ultrasonic noise AND minimising transient distortion (hence transient optimised). A full tech document we'll publish in due time.
External Clocks
Our policy is to not comment other manufacturers' products, therefore it's up to a user to know what type of a separate clock device he has. The Pro iDSD has several adjustments:
The standalone setting is appropriate for any use where the iDSD Pro does not require any external synchronisation to a house clock. Most commercial clocks of lesser quality (regardless of cost) will produce worse results than the internal oscillator of the iDSD Pro.
The atomic clock setting (the Atom symbol) enables the input only and is appropriate if a suitably high grade external clock is used. We wrote in the past that our recommendation is Stanford Research System PERF-10 or better, where 'better' means objectively even lower phase-noise.
The DARS setting is suitable for studio synchronisation use. Please see the AES Standard - AES11-2003.
The 10MHz setting (the squarewave icon) is intended to be used for example with multiple iDSD Pro machines set up for multi-channel operation. This mode enables both 10MHz input and 10MHz output.
It is acceptable not to provide a 10MHz on the input in this mode and instead to apply a BNC terminator and only use to 10MHz output to synchronise other devices with 10MHz clock inputs.
So if a 10MHz clock of suitable quality (> SRS PERF-10) is used in a system with only one iDSD Pro, the atomic clock setting is correct, even if the clock used is not an 'atomic clock', but standard 10MHz one.
Clock Sync is handled transparently without any particular details displayed, only if there is a clock error will there be an error message.
External Clocks - the TL;DR
If one doesn't know exactly what's what, to not mess around with external clocks is our sincere advice. In most cases the result will be inferior in comparison to the clock inside iDSD Pro.
For an external 10MHz clock with a single iDSD Pro
or with a clock that has multiple parallel outputs, the 'Atomic' position is the right one.
If multiple iDSD Pro machines are connected as a 'ring clock' or if only one is used as a 10MHz source, the 'squarewave' position is the right one. Then all iDSD Pro should be connected as a closed 'ring' or the sync output should be connected to a device that must be synchronised and able to accept a 10MHz reference.
There is no specific display if the external clock works correctly, though there is an error message if it does not.
Network Playback via DLNA
We have tested iDSD Pro with a range of DLNA software under both Windows and Android; JRiver, Foobar2000, AudioNet RCP and Linn Kinsky. Android requires rooted (hacked) smartphones for streaming and we do not recommend this, but it also works.
The iDSD Pro can be added directly to Windows as 'Digital Media Renderer' as shown here:
Please raise any network functionality related problems you might encounter with our support team, however please note that we can't and won't provide support for third party applications.
Since JRiver can be tried out for free, we recommend using this software to validate that the network playback via DLNA operates as intended. Instructions and background for JRiver use with DLNA Media Renderers are to be found here:
Here are some additional shots of our Pro iDSD seen in AudioNet RPC and Foobar2000: