QA-550 SD card 16/44.1 WAV transport

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C

Cola

Member
Joined 2006
EUVL said:
> What is the purpose of the diode at the input when it is feed with dc input? Can it be bypass when it is supply with battery power?

Prevent wrong PSU polarity; can be bypassed (at own risk).
I wire my supply directly at the cap after the power switch.

> Has anyone manage to bypass the output transformer?

Never used the SPDIF. Always been using I2S.

> Any improvement to the SQ when the above are bypass?

Suggest you try I2S first. Cannot be easier with a TDA1543.


Patrick
Click to expand...

Thanks. I am using AD1865. I think it is not that straight forward
 
W

windwss

Member
Joined 2006
Need help!
How to connect the IS2 from QA550 to TDA1541A DAC?

I’m using TAD 1541A, it only have connection as below:

1) LE/WS

2) BCK

3) DATA L/DATA

4) DATA R/SCK

5) GRND (A)

6) GRND (D)



Whereas on QA550, it have

1) LRCK

2) DAT

3) BCK

4) MCK

5) GND





So MCK shall connect to LE/WS?

LRCK to DATA R/SCK??
 
K

KlipschKid

Member
Joined 2007
32Gb cards

Hi,

I got one of these and just started to modify it. I'm wondering if it can support a larger screen with more characters ? Anyone tried ?

So far I've used it with a Sandisk Extreme III 16Gb sdhc, a class 4 Sandisk micro-sdhc and an A-Data 32Gb class 10 micro-sdhc. All good.

Here's a picture of the mods so far.

5977454035_59a5cce9fa_b.jpg


The Rubycon 470uF 25V cap is replaced with Sanyo 470uF 16V - a tight fit. The 2ppm TCXO is replaced with Vanguard 0.3ppm. I don't know what the ps/phase noise of these two are but there is more definition with the Vanguard. The input rectifiers are removed and a Sanyo 100uF 16V input cap is added across input voltage, followed by series ferrite bead, and then Vishay MKP 3n3F to create a Mhz filter.

Once these changes have burned in and the sound has become familiar, I'll try some better regulation.

Cheers,

Tom
 
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K

KlipschKid

Member
Joined 2007
...anything substantially larger than the original ? I gather it won't support anything other 8x2, but I'm sitting 2m away so I'd like something easily visible....so I'm thinking a 2" high, 4" wide display with backlight. Possible ? 58mm x 32mm is the biggest I've seen so far.
 
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G

glt

Member
Joined 2004
diyaudio.com/forums/showthread.php?s=&threadid=140669
KlipschKid said:
...anything substantially larger than the original ? I gather it won't support anything other 8x2, but I'm sitting 2m away so I'd like something easily visible....so I'm thinking a 2" high, 4" wide display with backlight. Possible ? 58mm x 32mm is the biggest I've seen so far.
Click to expand...

The way character LCDs behave, any change in format (eg 8x2 to 16x2) will require firmware changes. I have seen "large" 20x4 displays where the characters are larger, but I have not yet seen large 8x2 LCDs
 
K

KlipschKid

Member
Joined 2007
Hi,

Thanks for the replies guys - it seems I will have to give the bigger screen a miss as I can't find anything larger either. I've posted this in the QLS forum just in case. I wonder if a blue/white w/backlight will be easier to read from a distance....

I can't write firmware - I can't even manage i2c code - the best I ever managed was some Fortran and Basic many years ago. I have an src4193 project on hold for years now because I'm stuck with coding it.

BTW, the Vanguard seems to have had a positive effect - before, the sibilance on female vocals was a little hissy, mushy and overblown. Now it's tighter and more defined and there's more resolution everywhere. It's subtle but appreciably better. I still find the sound to be a little too "digital" at the top end but I expect that is the CS8406 and spdif output. I intend to remove the optical output and add an rj45 socket for I2S and feed that into an AMB y2.

I ordered a 74VHC to buffer the I2S but I've never used one of these before so I'm not 100% confident about how best to connect it up. I'll give it a go and post some pics.
 
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