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Old 18th March 2019, 04:25 PM   #471
pcgab is offline pcgab  United States
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tda1387 dac pcb "front end"
Quote:
Originally Posted by stellarelephant View Post
Twocents, congrats! I really love the sound Matt's original 1387 hat over headphones. I look forward to your impressions of the imaging over speakers.

Gable,
Your chassis looks very nice. Cool that you have preserved all of the Pi's connectivity options. Are you going to include an antenna for WiFi, or will you strictly use Ethernet? I have modified the 3b+ with an external antenna and can post details and pics if anybody is interested. I even have a few leftover U.FL sockets and shielded antenna cables to share...

I hope to start putting together a Digikey cart for this project over the weekend...
Ultimately, I will likely use ethernet only. However, I have some usb wifi adapters that I've used with other pi's and may test one or two of those.

I would love to see your modified 3b+ antenna setup.

Cheers,
Gable
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Old 26th March 2019, 02:42 AM   #472
stellarelephant is offline stellarelephant  United States
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I am going with Mouser for parts, mainly for ease of ordering with Matt's BOM. I'm still kicking around my final parts decisions with my friend Greg Stewart, but hope to order soon. I think we are going to use the full 2K7 value for our I/V resistors to get max output...Susumu RG series most likely.

As for the Raspberry Pi antenna mod, here are the links that I used myself to get going:
DIYA Member Bvlabs posted some great pics and a link here.
and
This hackaday tutorial describes the mod well too.

Scratching the mask for mounting the U.FL socket is easy. The zero ohm 0201 resistors, however, are on the verge of invisibility. You only have to remove one of them to break the connection to the on-board antenna. You could reuse it to make the connection to the new socket, but it was so infuriatingly tiny, I just threw it out and used a single strand of copper wire to go directly from the vacated solder pad to the socket terminal. My phone pics aren't great, but here they are.

If you aren't using an isolator in you Rpi stack, you WILL hear more WiFi noise leaking into your audio than you did before...for me it is roughtly 2-3x as loud, and I am only using a 3dbi antenna. With an isolator, it is completely gone--just as silent as before the mod. I plan to take the isolator out at some point and see what a ferrite snap bead can do on its own...
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Last edited by stellarelephant; 26th March 2019 at 02:44 AM.
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Old 26th March 2019, 12:52 PM   #473
pcgab is offline pcgab  United States
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tda1387 dac pcb "front end"
0201 is ultra tiny!

Thank you for the reference material, if I go wifi, I'll definitely try the mod.
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Old 26th April 2019, 07:18 AM   #474
kp93300 is offline kp93300  Malaysia
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I like the transparency and simplicity of ground gate current buffer used in the Red baron TDA 1541 board.
Will it work if I attached the output from TDA 1387 to 2SK 216 circuit posted below ??
Is there other alternative to 2SK 216 ?
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Old 26th April 2019, 08:20 AM   #475
kp93300 is offline kp93300  Malaysia
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Matt, please ask mod to delete my post if this is not the correct thread to post the question.
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Old 29th April 2019, 05:39 AM   #476
mllum is offline mllum  Malaysia
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Quote:
Originally Posted by matt_garman View Post
Sorry, previous post was the wrong schematic. (Previous is the balanced RPI Hat.) Here's the right one!

Moderators, please feel free to delete the previous post.

I refer to the schematic for version 1.2.

Forgive my ignorance, but what are jumpers J3 and J4 for? I had some boards made from the gerbers and I believe that when I checked the traces for continuity, one of the pads, I cannot remember which offhand, but J4 I believe, had no connection to the ground of the RPI.

Are the jumpers to be closed or left open?

Please clarify. Thanks in advance
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Old 29th April 2019, 05:56 PM   #477
matt_garman is offline matt_garman  United States
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tda1387 dac pcb "front end"
Quote:
Originally Posted by kp93300 View Post
I like the transparency and simplicity of ground gate current buffer used in the Red baron TDA 1541 board.
Will it work if I attached the output from TDA 1387 to 2SK 216 circuit posted below ??
Is there other alternative to 2SK 216 ?
No problem asking that question in this thread, but I'm afraid I don't have enough knowledge to give any kind of useful answer. Unless someone else pipes up, you might want to take the question to another thread if only to get more eyes on it.


Quote:
Originally Posted by mllum View Post
I refer to the schematic for version 1.2.

Forgive my ignorance, but what are jumpers J3 and J4 for? I had some boards made from the gerbers and I believe that when I checked the traces for continuity, one of the pads, I cannot remember which offhand, but J4 I believe, had no connection to the ground of the RPI.

Are the jumpers to be closed or left open?
They need to be closed. There are three different grounds on the v1.2 design, J3 and J4 tie them all together. (I got away from that in later versions and just had one big common 0v reference.) But yes, when those jumpers are open, you won't see any continuity to RPI ground.

Hope that helps!
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Old 30th April 2019, 03:22 AM   #478
mllum is offline mllum  Malaysia
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Matt,

Thanks for your quick response. I am much obliged.
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Old 20th May 2019, 05:12 PM   #479
vipulpatel83 is offline vipulpatel83
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Quote:
Originally Posted by twocents View Post
Problem solved! Thank you very much abraxalito for your advice. I actually found two dry joints on the right channel. All is good now and I am absolutely ecstatic.

Here is my test setup. From left to right - Class A Headamp, Low-noise PSU, DAC board, Amanero.
First sound is fantastic - I have never heard so much detail and warmth with "Take Five - Dave Brubeck Quartet". Cannot wait to get it running with the RPi.

Thank you so much Matt for this fantastic project, and for supplying the free board!
twocents, Nice setup. I might try the same. I have received my SE 1.6 boards and components, Amanero USB2I2S is on the way (for my Soekris DAM1021 build).

I need some help to understand the connections J4 -> Amanero :

1. I am confused with I2S_WS (from the schematics), if its to be connected to CLK or FSCLK on Amanero?
2. Also, as per schematics, 1-3-5 pins on J4 are to be connected GND. Did you connect all of these to Amanero GND pins.

TIA
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Old 20th May 2019, 06:31 PM   #480
twocents is offline twocents  South Africa
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tda1387 dac pcb "front end"
Quote:
Originally Posted by vipulpatel83 View Post
I need some help to understand the connections J4 -> Amanero :

1. I am confused with I2S_WS (from the schematics), if its to be connected to CLK or FSCLK on Amanero?
2. Also, as per schematics, 1-3-5 pins on J4 are to be connected GND. Did you connect all of these to Amanero GND pins.
I actually borrowed the Amanero from a friend just to test my DAC before connecting to the RPi. So, I cannot check physically anymore, but I made a note somewhere that WS connects to FSCLK on the Amanero. For GND you only need to connect one of the three pins on the PCB to the Amanero GND. So, only 4 connections. Hope that helps.
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