Tag Archives: I2s

i stole your i2s-eiaj convertor design?

there has been allegations that i copied someone’s i2s to eiaj convertor and passed it as my own. and according to the accuser, this scheme was posted on my forum in 2009.

so i was the criminal who copied a schematic posted on my forum, then made a pcb and sold it as my product. hmm…

i see… but first thing first, why would i want to copy someone else’s design when i already have an i2s to eiaj convertor myself?

first thing first, i2s and eiaj are just digital analog convertor (dac) chip’s input format standard. i2s is the most popular but the dac chip i like, tda1545a, uses eiaj, so i got to use eiaj.

now way back in 2007, i did a usb monica.  this design uses the pcm2706 usb receiver and i used its i2s output to  convert it to eiaj, then feed the tda1545a dac chip. so i already have an i2s to eiaj convertor. because if i didn’t have such a convertor, i would not be able to make a usb dac using tda1545a.

i was even bold in 2007 to make this claim that my usb monica is the first usb dac in the world to use a non-i2s input dac chip. in my case — tda1545a.

(i2s input chips like tda1543 and tda1541 can be hooked to the pcm2706 directly, thus no need for any data conversion.)

so if you just apply some logic thinking…

2007, i introduced the usb monica, which has an i2s-to-eiaj circuitry in it.

2009, this accuser posted his version on my forum.


does it make sense?

besides i have been selling online since 2002 and built up a reputation. would i be so stupid to soil my name, built over almost 10 years, for a product selling for  sgd43 (~usd30)?

if you look at the pcb module above, there are 4 chips. 3 chips to handle flip flop duties and 1 as a buffer.

the accuser’s design uses 6 chips.

besides, i made a mistake in my i2s-to-eiaj convertor which makes it stand out from the rest. the Left/Right channel is supposed to be swapped as this is one of the difference between the 2 data formats. i forgot to do this. this mistake is seen in usb monica as well as this module above, named black crow.

so based on time line,  mine came first by a good 2 years.

based on motive, i hope you could give me a bit of a credit and not regard me to be so stupid to sell out my good name for such a low priced product!

based on the number of chips alone, it’s different!

i rest my case.

i have no further comments on this. if you still think i’m a rascal who stole someone else’s design, after all this explanation above, nothing further i write could convince you.

Opened up the Squeezebox Touch

Having used the Squeezebox 3 for a few years already (and almost modified it to death),  I look forward to the new Squeezebox Touch.

Touchscreen, 24 bit/96 kHz, capable of playing off HDD, SD card… Now that’s a lot to like about it.

But the sonics (I’m using only SPDIF output), though much better off the stock Squeezebox 3) still leaves a lot to be desired. With my pulse trans tweak, I was able to improve its sonic immediately but I just have to do more!

But opening up this bugger isn’t like the SB3 at all. There are just a few screws on the SB3 so it’s really easy to take it apart. This fella, you need to be very careful. Thanks to John Swenson who described in detail what’s the journey ahead of me.

After quite a while fiddling with it, I finally managed to open it. And here’s what I see.

The flexi PCB cable, which links up the touchscreen to the main PCB, uses a scary tiny connector. You need to lift up its hinge to free the cable.

Front view of the PCB.

Rear view of the PCB. I could see the DAC is AKM4420.

As you could see, lots of scary IC packages inside. TSSOP, TQFP, BGA… All this makes modding difficult. 0805 package SMD components look really big compared to the little fellas here.

If you want to tap the I2s signal, you could refer to the AKM4420 as this chip uses I2s format. I still couldn’t figure what’s the SPDIF circuitry inside. There’s definitely no pulse trans but since this could be installed externally, may not be that big of a problem. I would love to remove the SPDIF RCA socket and replace with a BNC.

Oh well, have a look at it and let me know what you think could be done to it.