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Old 13th August 2012, 01:46 AM   #21
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Thanks again abraxalito for your help.

I have done a bit more reading into various DAC chips and receiver chips and due to having a good knowledge and experience with PIC microprocessors and various other digital devices, I have decided I would like to try and make a DAC instead of buying the eBay one. I think it is better to learn by building from scratch.

I see why the 1543 and 1545A chips are not interchangeable, as they run 2 different formats or protocols from the receiver chip.

I found a site that implements a CS8412 and a TDA1545A.....

Match Made in Heaven: Batteries and Non-OS DACs

You can get CS8414 chips on eBay which are pre-soldered onto DIP adapter, so I think I may try it. Please could you have a look at the schematic on this site and tell me what you think. I understand most of it apart from the string of diodes on the LM317! I've used LM317 chips before, but not like this. Is the ADJ (pin 1) connected to the top of the series of diodes, or is it just crossing?

If I were to use the schematic on this site and I did parallel some 4515A chips, do I need to change any of the resistors on the output?

Sorry for all the questions, the internet is a great source of information, but sometimes it has way too much and can be misleading.
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Old 13th August 2012, 02:09 AM   #22
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I just found another similar schematic:

Click the image to open in full size.

This one uses a 1543, so to use a 1545A, I would have to set the mode of the CS8414 to output EIAJ, correct? I'm still not sure about the power supply and how to parallel the chips though
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Old 13th August 2012, 02:14 AM   #23
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Quote:
Originally Posted by portreathbeach View Post
I have done a bit more reading into various DAC chips and receiver chips and due to having a good knowledge and experience with PIC microprocessors and various other digital devices, I have decided I would like to try and make a DAC instead of buying the eBay one. I think it is better to learn by building from scratch.
I used to think so too but in recent years I've changed my mind. The satisfaction I find comes from the feedback loop - build something, listen and see how it sounds. Building totally from scratch means a long delay before you can get to listen, so enthusiasm tends to lag a bit there (maybe I just have ADD ). Modding something that works straight out of the box means you can try a fairly simple tweak - like removing those two green caps - and get practically instant feedback. I've found such tight loops are the real essence of learning by doing.

I've also used PICs in the past but these days I'm sold on ARMs because they do so much more (the 32bit PICs are quite good though I must admit but I don't see a long-term future for MIPS).

Quote:
I found a site that implements a CS8412 and a TDA1545A.....
I'll take a peek and get back to you on that in another post.

Quote:
Sorry for all the questions, the internet is a great source of information, but sometimes it has way too much and can be misleading.
No apologies required for questions If there's something I'd suggest to improve DIYA in general it would be fewer claims made and in their place more questions asked
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Old 13th August 2012, 06:46 AM   #24
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Default Websites can indeed be misleading...

Back to the link you cited. Almost the only thing I agree with that guy on is that Monica Bellucci is a babe. On technical stuff I'd barely give him the time of day.

Down and dirty - he's got a string of diodes hanging off his LM317. I'm wondering why he'd do that - diodes have a really poor dynamic impedance and putting several in series compounds this. But then I notice he credits Thorsten for the idea - this is where the plot thickens considerably coz Thorsten is pretty switched on about DAC design and I hesitate slightly whenever I cross swords with him

Fortunately he provides the link to what Thorsten actually said and it turns out to be quite different from what he's implemented. The diodes are the same but the original suggestion was to run several hundred mA through them - this lowers their impedance quite nicely. Yet our Monica fan has set the output current of his LM317 at 52mA (1.25V/24R) - barely enough to power the TDA1543, leaving nothing over for the diodes to act as shunts. Add to this his choice of 1mH inductors in the receiver power supply leads me somewhat reluctantly to just one conclusion - give him a wide berth.
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Old 13th August 2012, 08:46 AM   #25
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I hope this isn't hijacking - but this kit is giving excellent results with the mods developed by Dario I. The thread is very long but there are some good comparisons to other DIY and commercial DACs

DAC 2496 (AK4393)+CS8416+AK4393+5532 Kit | eBay

DAC 2496 (AK4393) DAC KIT With CS8416+AK4393+5532

The bare PCB with pre-mounted SMD chips is also available from the same vendor. It is an easy to build solution with top end sound and I am suggesting it only if you are not confining the scope here to the unit in the first post of this thread.
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Old 13th August 2012, 09:45 AM   #26
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Thanks again for the reply. I do feel that I want to build a DAC from scratch now I've read into it a lot more. Have you any good schematics using 1545As?
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Old 13th August 2012, 09:52 AM   #27
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Sorry, I don't. If you haven't been there already you might find some support and ideas on this thread. Pushing the limits of TDA1543 NOS DAC
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Old 13th August 2012, 10:13 AM   #28
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Quote:
Originally Posted by portreathbeach View Post
Have you any good schematics using 1545As?
What difficulty level were you looking for? I haven't drawn up any whole schematics for my DACs over the past year or so, just have part schematics distributed through my notebooks. But I could cobble up something in a couple of days. My 4 montns old design I already mentioned has 8 DAC chips. The one I'm working on now is considerably more complex, with 19 chips - you can see the first prototype on the DAC sticky thread (post #33) - rather a lot of chips and wiring, but I'm simplifying it a little for the beta prototype
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Old 13th August 2012, 11:19 AM   #29
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I'm thinking maybe 8 DAC chips also. Any schematics, or part schematics would be greatfully received.
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Old 13th August 2012, 11:31 AM   #30
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Let me poke my head in here again. That many DAC chips is an unfamiliar approach to me and maybe others. Can someone please give a short explanation of the benefits and theory involved?

Thanks.
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