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AK4458 multichannel DAC with I2S input
AK4458 multichannel DAC with I2S input
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Old 8th February 2017, 07:18 AM   #21
zarandok is offline zarandok  Austria
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Some schemtics and a modified layout....
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File Type: jpg System schematic_1.jpg (302.7 KB, 430 views)
File Type: jpg PS schematic_1.jpg (327.8 KB, 425 views)
File Type: jpg 3D view_4.JPG (156.4 KB, 431 views)
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Old 9th February 2017, 07:30 AM   #22
zarandok is offline zarandok  Austria
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I have made some filter simulations with full-balanced OPA-s. The -3dB freq. corner is about 200kHz, the output Vrms is 1,97V.

Another PS schematic to show that the board can be tested only with two regulators...
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File Type: jpg AK4458VN filter simulation.JPG (105.0 KB, 398 views)
File Type: jpg AK4458VN filter transfer amplitude.JPG (85.9 KB, 381 views)
File Type: jpg AK4458VN filter transfer phase.JPG (88.7 KB, 67 views)
File Type: jpg PS schematic_1_TEST.jpg (410.3 KB, 114 views)
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Old 9th February 2017, 09:18 AM   #23
zarandok is offline zarandok  Austria
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It is not necessary to use all of the two IC-s, because there is no need for outside I/V conversion by this chip (the DAC has voltage outputs). The first stage can be simply shorted with a bridge...
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File Type: jpg OPA 3D view_1.JPG (76.6 KB, 159 views)

Last edited by zarandok; 9th February 2017 at 09:24 AM.
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Old 9th February 2017, 11:04 AM   #24
fluid is offline fluid  Australia
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Quote:
Originally Posted by zarandok View Post
Some schemtics and a modified layout....
Nice, I have LX521 with a Najda and UCD amps.

What is LF50 and LF80 switching regs? If they are I would put an LC filter after them. If not 9V AC transformer to 3.3V is going to burn some heat. I had to switch to 6V transformers in another DAC I built as the 9V transformer with a 5V regulator made the heatsink way too hot for me to be happy with.

I have also recently had some custom voltage and current spec multi winding R Core transformers made in China and bought through Taobao. They were very cheap and really high quality. Absolutely no hum.
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Old 9th February 2017, 11:33 AM   #25
zarandok is offline zarandok  Austria
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Join Date: Feb 2015
The problematic is if I want to use the 5V shunts, they need about 8-9V input DC. With one double seconder transformer (one side for analog and one for digital) I can not really choose different voltage values - perhaps a custom made from china...

The LF50CV is a "Very low drop voltage regulator with inhibit function". I choosed it because of the low 50uV noise, 1A, and the simple TO-220 package. There is not a lot of type with this simple package and big current...
http://www.st.com/content/ccc/resour...CD00000546.pdf

My actual questions are:
- should I supply the 1,8V regulator from the 3,3V or direct from the 5,0V?
- I should lower the shunt currents by the Vref pins, but I don't know how much current they really need!? A 2x5VA (556mA) transformer for 3 pcs. 60-70mA shunts and pre-regulator will be marginal (if at all)....

How do you like the LX speakers?
I am not so rich to have the best things, so I have the minis and a DIY DAC and amps...:P

Last edited by zarandok; 9th February 2017 at 11:40 AM.
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Old 9th February 2017, 12:20 PM   #26
fluid is offline fluid  Australia
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Quote:
Originally Posted by zarandok View Post
The problematic is if I want to use the 5V shunts, they need about 8-9V input DC. With one double seconder transformer (one side for analog and one for digital) I can not really choose different voltage values - perhaps a custom made from china...
This is one I bought, has 12V x 2, 9V and 6V.

P1000742.jpg

Quote:
The LF50CV is a "Very low drop voltage regulator with inhibit function". I choosed it because of the low 50uV noise, 1A, and the simple TO-220 package. There is not a lot of type with this simple package and big current...
http://www.st.com/content/ccc/resour...CD00000546.pdf
Is it a switcher? I can't tell and there doesn't seem to be any thermal information.

Quote:
My actual questions are:
- should I supply the 1,8V regulator from the 3,3V or direct from the 5,0V?
- I should lower the shunt currents by the Vref pins, but I don't know how much current they really need!? A 2x5VA (556mA) transformer for 3 pcs. 60-70mA shunts and pre-regulator will be marginal (if at all)....
Probably depends on the quality of the 5V and how much heat will produced from the voltage drop. Regs on regs on regs can be a recipe for oscillation.
The DAC itself shouldn't need much current.

Quote:
How do you like the LX speakers?
I am not so rich to have the best things, so I have the minis and a DIY DAC and amps...:P
Ha ha, well I learned a long time ago to just bite the bullet and get what I want because I will always end up there eventually, saves money in the long run ...

I like them a lot, but like all dipoles they need the right sized room to work to their best. I don't have enough room around them where they are now and you can hear something which sounds a little like extra reverb has been added to some recordings. Others are so good it is amazing.

The minis are supposed to be almost as good, particularly if you have some subwoofers. The fact you can place them closer to the walls would actually help me where I am now.

I built my own amps and Najda, not cheap though. I used LM4780 chip amps for Orion but they are only really just about powerful enough.

IMG_0170.jpg

IMG_0219.jpg

IMG_0063.jpg
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Old 9th February 2017, 01:10 PM   #27
zarandok is offline zarandok  Austria
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Thanks for the pics, looks great!
This "Nadja" uses a 8ch Cirrus DAC or? Is it not a bad sounding...?
Ok, I'll make the PCB that the 1,8V can be supplied from the 5V direct.
I'll consider this 4x seconder r-core tranformer... There are 2x15+2x9V types but I must ask for other values or?
Attached Images
File Type: jpg P1160571.jpg (663.6 KB, 136 views)
File Type: jpg L25D.jpg (414.2 KB, 122 views)

Last edited by zarandok; 9th February 2017 at 01:21 PM.
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Old 9th February 2017, 01:23 PM   #28
zarandok is offline zarandok  Austria
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Schematic of LFxx regulator. Is it a switcher (I don't think so)?
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File Type: jpg LFxx.JPG (41.7 KB, 153 views)
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Old 9th February 2017, 02:59 PM   #29
fluid is offline fluid  Australia
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Quote:
Originally Posted by zarandok View Post
Thanks for the pics, looks great!
This "Nadja" uses a 8ch Cirrus DAC or? Is it not a bad sounding...?
Ok, I'll make the PCB that the 1,8V can be supplied from the 5V direct.
I'll consider this 4x seconder r-core tranformer... There are 2x15+2x9V types but I must ask for other values or?
Yes the Najda uses a Cirrus chip. Sounds pretty good to me, I haven't easily been able to compare it my other DAC's but I have used it as a stereo DAC for Orion and to put in a little bit of DSP HF roll off as I prefer that sound, didn't seem lacking in that use.

I ordered my transformers direct from Zerozone on Taobao, I sent them a message with the voltages and current I needed and they built them to my specs. Size and core used depends on the current you want. I got one with 3 x 6V windings and another with 5 separate windings. Price was only slightly more than a 2x15 or 2x9 as I used a bigger core for more current.

I put the 3 x 6V one in this DAC to reduce the heat from the regs.

P1000723.jpg

I have the Ali Wang messenger app on my computer and started with Chinese translation but they were good and replied to me in English. It isn't a really easy process but I am getting much better at communicating with the Chinese sellers.

I can't tell from that block diagram what is going on as that could be any regulator really.
Seems similar to the LM2941 which I thought was a switching regulator, maybe not?

Last edited by fluid; 9th February 2017 at 03:04 PM.
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Old 10th February 2017, 08:58 AM   #30
zarandok is offline zarandok  Austria
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Nice, you have already tried some DACs....
The LFxx regulator idea comes originally from the DDDAC (google...)
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