Recommended memory card for Streamit players
Streamit recommends Transcend SDHC cards for use with the Streamit Internet audio devices. Many of the large In-store audio customers use Transcend SDHC cards for storing, updating and playing audio, on many thousands of devices. Mainly the 8GB and 32GB class 6 and class 10 cards are used.
A few years back Streamit evaluated a number of cards from different manufacturers. Performance and stress tests were implemented to evaluate the cards, focusing on durability, reliability and speed. Transcend cards were found to be the best compatible and reliable cards, outperforming the rest of the brands tested.
Streamit only performed tests on a number of brands which were the most commonly used and broadly available at the time the tests were carried out. There could very well have been other brands which might have outperformed Transcend. Looking at the major implementation differences between the manufacturers (e.g. electrical properties) it was decided to recommend the best performing tested brand. Other brands could be used, if the customer was satisfied with the performance.
For some time our customers have been using Transcend cards with satisfaction. The Streamit SIR120 device experiences some issues with the newer SDHC cards (8GB and 32GB, C10), manufactured in 2013. There are no issues with the older 8G and 32G cards.
Streamit investigated the issue, performed electrical measurements, reviewed the driver and consulted the SD specification. It was concluded that there are no hardware/electrical issues with the SIR120 hardware or the card driver implementation. The issues must have been introduced by changes in the hardware of the SD card. Under certain conditions, the card seems to enter a state when it stops to function properly.
Streamit analyzed whether the issues could be resolved by varying timing and communication speed, but to no avail.
The SD card is the key component in using Store-and-forward on Streamit’s audio devices. We always put a lot of effort in making sure the hardware and software follows the SD specifications. However, there are numerous manufactures each with an own implementation. These implementations are also continuously updated and Streamit has no influence on that.
The SD cards that have been used are consumer devices and the manufacturer is constantly under high price pressure. To cut production costs the manufactures look at cheaper components. These newer cards built with cheaper electronics, get sold under the same product name, making it impossible for the end user to identify. The user thinks he is using the very same card when the main components are actually different.
It seems that we have reached a point when we cannot guarantee full support, for any of the available consumer memory cards. There might be some out there, but we would not know where to start looking if we wanted to. And if we found one, we would not know how long they would be usable before the same issue gets encountered.
We had a strong feeling that the consumer cards, where you have no say on hardware and implementation are not a good option anymore.
Custom Trancend cards
Streamit contacted Transcend with the issues being encountered when using the newer cards in the SIR120 devices, to see whether anything could be done.
Transcend confirmed that there have been hardware changes with the newer cards, somewhere end of last year (2012). To reduce costs a cheaper flash memory (TLC) was used, with a lower endurance limit than the previously used MLC memory. TLC is a good fit for low-end basic products, but is not recommended for important applications which require frequent updating of data.
Another change which was made at the same time as the change in memory type, was the use of a different controller. Transcend and Streamit believe that the issues we see when using newer cards in the SIR are a result of the change in the card’s controller.
Streamit is also not satisfied with the reduction in write/erase cycles which results by switching from MLC to TLC. Although these cards might very well be acceptable for some basic consumer electronics, they are not acceptable for professional applications.
Transcend is prepared to deliver Streamit custom cards. These cards would be using the old controller as well as MLC flash memory). This would be possible for size 8GB and 32GB, the most commonly used by our customers. The expectations are that these cards will be available within a few weeks from now.
These custom cards will be the only cards which Streamit will officially support. Other cards may always be used at own risk. This also means that Streamit will not offer free support for other cards anymore.
How about the LISA?
The SD host can communicate with and SD card over one of the available physical interfaces; SPI or SDIO interface. While for the SIR120 the SPI interface is used, the LISA communicates over the newer and faster SDIO interface.
The tests until now have shown that the LISA has no issues with the newer Transcend SDHC cards. We believe that the LISA will support more SD cards, better than the SIR120. The extent of it has to be seen in practice.
Also for LISA devices, Streamit recommends the same cards as for SIR120, the custom Transcend cards also recommended for SIR120 devices.