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Old 28th May 2013, 06:47 PM   #4841
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Single chip PCM56 should be ugly.
It is done in really old, cheap CDPs, the idea is of "cost reduction" when you could use 1 mono chip instead of 2 chips. Twice cheapr!
The performance is bad, that's why you don't see 'em in DIY.
Really weird thing, the separation of left and right channel samples is being done in ANALOG domain, with analog switches driven by LRCLK signal. Sample/Hold may be there too, somewhere.
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Old 28th May 2013, 08:13 PM   #4842
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Default NOS didn't work

Well gave it a go. CS8414 in master mode, 3 jumpers across SAA7220 socket. Nothing. Put back to 4X OS and no issue. Guess I will see if the Red Baron board shows up and give it another go. TBD.... Still a NOS virgin.
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Old 29th May 2013, 12:48 AM   #4843
Eldam is offline Eldam  France
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Hi ST3P,

Thanks

This Akai CD players with one PCM56 and two Toshiba op was the best tweaked one I had. Better than tweaked TDA1541, 1540, 1543, 1545, PCM1701, AD1865, SA78xx. but I never heard top DAC or top cd players. I think pcm56 is not a low quality dac chip. Texture of Saxophone, harmonica were the better I heard at home. Hmmm maybe I woud wait for a second pcm56... but I'm sure that the difference is not really here. Nagra make cd players with "normal" dac chip with good result. I would buy 2 ad1862 but too expensive for my little technical skill. So i have some TDA to play with... but the I/V & buffers stages... but the input stage with I2S longer than 3 inches...Hargh with which clock: WHO have I to believe. Why not try too Bernard pcm56 & analog filter way ? (but not with 32 chips...too dangerous all this boards with champagnes... plop....bubbles...burn...s....t my DAC !). I would like a good dac for my squeeze box and i'm not really sure that a bad tweaked I2S from a squeezebox is better than a good Spidf chip receiver...

Last edited by Eldam; 29th May 2013 at 01:02 AM.
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Old 1st June 2013, 02:28 AM   #4844
roger57 is offline roger57  Canada
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hi studiostevus,

I see this is a quite old post, but i hope you can still answer my question.
Can you tell me which capacitor you settled on? I'm curious about your comments regarding the acrylic SMD caps. I also use 1uF/16V (low impedance Panasonic) and find them not so transparent, and a bit heavy in bass. I have read that it's not so much the type, but the larger value that has this effect.

My caps are mounted directly beside the socket pin, so electrically they are as close as possible to the pin to mitigate any impedance issues.

I'm going to try a 0.22uF and see how they sound. I'd be interested in hearing from anyone else who has found any differences in this regard.

Thanks!
Gary


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Originally Posted by studiostevus View Post
Thanks John, very interesting!

I am currently running on Salas shunts, and playing around with the local decoupling of the power supply lines. What are your findings there? I see you only use a 1uF acrylic at the tda.

I have tried combinations of
-1uF acrylic smd
-22 uF BG STD
-270 uF Oscon SEPC

Not sure what I like best...
-22uF BG only --> seems like things are missing
-22uF BG + 1uF SMD --> added smoothness
-22uF BG + 1uF SMD + 270 uF Oscon --> Added bass
-1uF acrylic SMD only --> listening to it now, it seems very bass-heavy, but also liquidy smooth. I am not sure if I like the amount of bass... on the other hand it's quite analog now. It's less transparent though

What do you think?
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Old 2nd June 2013, 12:58 AM   #4845
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Actually I got oscillations using salas regulators and decoupling caps.... So needed to remove all of them. Will try if there are any combinations that don't oscillate in the future....
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Old 2nd June 2013, 04:10 AM   #4846
wlowes is offline wlowes  Canada
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Quote:
Originally Posted by studiostevus View Post
Actually I got oscillations using salas regulators and decoupling caps.... So needed to remove all of them. Will try if there are any combinations that don't oscillate in the future....
Roger
I was pretty happy with OSCON SEPC 270u bypassed with a small film cap. .47n I think. Then ADDED BG N caps soldered directly on the tda pins. The BG definitely added as always that nice dark background and rich detail. Can't remember exact value of BG but likely 47uf. I think the key is to put the BG right on the pin IMHO. Sounds so darn good I just don't go back to mess with it.
Walter
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Old 2nd June 2013, 05:08 AM   #4847
roger57 is offline roger57  Canada
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Hi all,
I was referring to the DEM caps - 7 per side on the TDA1541A that Philips specified as 0.1uF in the data sheet. With such large values, I think you are talking about power supply decoupling capacitors?



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Roger
I was pretty happy with OSCON SEPC 270u bypassed with a small film cap. .47n I think. Then ADDED BG N caps soldered directly on the tda pins. The BG definitely added as always that nice dark background and rich detail. Can't remember exact value of BG but likely 47uf. I think the key is to put the BG right on the pin IMHO. Sounds so darn good I just don't go back to mess with it.
Walter
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Old 2nd June 2013, 06:42 AM   #4848
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Lytics have comparatively high leakage current and should really only be used on the msb dem pin, if at al.
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Old 2nd June 2013, 02:04 PM   #4849
wlowes is offline wlowes  Canada
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Quote:
Originally Posted by roger57 View Post
Hi all,
I was referring to the DEM caps - 7 per side on the TDA1541A that Philips specified as 0.1uF in the data sheet. With such large values, I think you are talking about power supply decoupling capacitors?
My mistake. I thought you were referring to the power supply.
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Old 2nd June 2013, 06:00 PM   #4850
oshifis is offline oshifis  Hungary
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As for the 2x7 DEM filtering capacitors, I have been listening to the DAC with the capacitors removed altogether for a while. Same as with NOS, it shouldn't work, but it sounds impressive!
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