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Old 14th September 2011, 11:52 PM   #21
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Venci - forgot to mention :

My clock outputs 2.8, 5.6 and 11.289 so it was easy - apologies.

Anyone with fixed 11.289 clocks will need your design - which on your Alpha 5 looks fantastic - like the use of the ribbon cable and the pc power supply twisted wire and plug - I've used them too - very handy !!

You can beef up your MSB caps to 2.2uf's ( throw away the 4 tants ) and use close tolerance silver mica 250pf across pins 16 and 17 of TDA.

You'll fall off your chair after you've done this

Andrew
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Old 14th September 2011, 11:58 PM   #22
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The 250pf cap replaces the 680pf blue box cap
This locks BCK at 352.8 - 680pf does not ( for DEM )

Andrew
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Old 15th September 2011, 07:57 AM   #23
simonov is offline simonov  Bulgaria
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Actually the picture shows a reclocking the the whole I2S bus. I didn't like this method. It's actually done by default in Alpha 5+ version of the player. I should update my article with my current reclocking setup. About that small 680pF cap - I'm about to make a DEM reclock and feed the external frequency to the internal oscillator.

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Venci
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Old 15th September 2011, 09:47 AM   #24
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Yep - that's the best way.....but you'll still fall off your chair

DEM re clock is fantastic
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Old 15th September 2011, 02:08 PM   #25
oshifis is offline oshifis  Hungary
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Quote:
Originally Posted by simonov View Post
And I'll try the 1541A with separate clock on pin 4. Venci
As far as I know, pin 4 is not used on TDA1541A in time multiplexed mode.
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Old 15th September 2011, 02:44 PM   #26
simonov is offline simonov  Bulgaria
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Well that's what Table 1, page 5 from 1541A datasheet says. I wonder why all the manufacturers had decided to link together pin 2 and pin 4, when pin 4 is actually unused That reminds of the way logic inputs of the IC's are treated. All unused inputs tied to ground or linked together with the used input pin.
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Old 15th September 2011, 09:07 PM   #27
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OK.....but I did this first.....

I forgot - it's been so long since I did the clock
Attached Images
File Type: jpg Cut TDA re clock.jpg (125.2 KB, 249 views)
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Old 15th September 2011, 09:16 PM   #28
simonov is offline simonov  Bulgaria
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Ahh so you have the pin 4 disconnected. I'll try this. I still wonder why commercial designers tie these together. Thanks for the tip

Regards,
Venci
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Old 15th September 2011, 09:54 PM   #29
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Yes, go ahead it works fine - forget the data sheet's !!

Pin 2 Bit clock @ 5.6
Pin 4 System Clock @ 11.289

....or is it the other way round ? haha !! ( joke btw )
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Old 15th September 2011, 10:37 PM   #30
josha is offline josha  United Kingdom
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No soldering tonight! Too much reading to do, especially now a clocks in the picture ;o) I couldn't find the 11.289 one earlier but it's just re-appeared, odd. I'll invest in one once I've got a few other things sorted.

I have learned a huge amount already, mostly about how important the placement of components can be to the sound. Until I plugged the op-amps directly into the sockets (i had double socketed them to make it easier to swap), it seems the extra socket really upsets them (I wouldn't have believed it could matter that much) but the magics back! - Is this a result of 'long' leads to the opamps or just too many crumby connections I wonder.

So, the next job is to get the PSU sorted for the 7220 (the whole things sitting in a box of to one side at the moment, a couple of wires looped in and under the chip.) Then I/V, probably just a simple, separate opamp board with a dedicated psu for now while I do my homework. Then....hmmm....clock perhaps, the 7220B.....better PSU.....

All this clock talk though......maybe I just hit the 'buy it now' button......
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