Carrie USB-Powered Headphone Amplifier
Mar 24, 2014 at 8:25 PM Post #872 of 913

Robin W.

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Have you guys been able to contact joneeboi yet?
I saw him a few weeks ago and I'd be happy to pass along a message or point him to this thread.  
He's been very busy with life but mentioned that he'd like to get back into this if/when time permits.
 
Mar 24, 2014 at 9:40 PM Post #873 of 913

tomb

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  Still untested, as my computer can't host the GrubDAC. Is it safe, for testing purposes, to power it from the 5 V rail of an ATX PSU, and sending it audio signal from my desktop DAC?
 

 

 


Very nice work, Kim!  It's great to see that PCB being put to use!
 
I wish the news was better on the GrubDAC.  I'm afraid you are unique in that regard - haven't had any other reports of incompatibility.  I forget the specific issue - do you think one of our new DoodleBugs could correct the problem?
 
Mar 24, 2014 at 9:52 PM Post #874 of 913

KimLaroux

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Very nice work, Kim!  It's great to see that PCB being put to use!
 
I wish the news was better on the GrubDAC.  I'm afraid you are unique in that regard - haven't had any other reports of incompatibility.  I forget the specific issue - do you think one of our new DoodleBugs could correct the problem?

 
Thank you for the kind words and for giving me the opportunity to tackle this project. 
 
I can't tell if the DoodleBug would help, as the problem seems to be with my computer. Fooling around with other USB devices, I was able to reproduce the problem, though not permanently as with the GrubDAC. 
 
I have noticed an improvement when using a short usb cable, containing a ferrite, soldered directly to the board. My goal is to assemble the unit and encase it, then try a very short, high quality USB cable containing at least one ferrite bead. I got my fingers crossed on that one.
 
Mar 25, 2014 at 7:06 AM Post #875 of 913

Avro_Arrow

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I can't tell if the DoodleBug would help,

 
Can you measure the voltage at the DAC when plugged into the laptop?
I might be able to loan you my Doodlebug to test with...
 
Mar 25, 2014 at 1:57 PM Post #877 of 913

Avro_Arrow

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Can you be more specific? Where/what do you want me to measure?


On the GrubDAC, measure between the 0V and 5V where the USB Cable would be soldered.
If the voltage comes out less than 4.75, the malfunction could be voltage related.
 
Apr 19, 2014 at 2:49 PM Post #878 of 913

KimLaroux

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On the GrubDAC, measure between the 0V and 5V where the USB Cable would be soldered.
If the voltage comes out less than 4.75, the malfunction could be voltage related.

 
I get 5.03 V at this point. The 3.3 V rail shows acceptable voltages too. I'm pretty confident the problem is with my laptop having lame USB ports, as the DAC works fine on my friend's Alienware.
 
I finally got around to test the Carrie itself and of course it doesn't work. I only get 2 V between V+ and V-. 
 
The DCP gets 5V fine, but measuring on the output pins yields nothing. Of course being a switching supply, I really have no clue how to debug it. Any idea where I should start?
 
edit:

Silly me tested the wrong pins, confused as to how to count them with the lack of some pins on the IC. I measure 2.12 V directly on the output of the DCP. It's 1.96 V between V+ and V-.
 
Apr 19, 2014 at 4:04 PM Post #879 of 913

Avro_Arrow

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The DCP is a pretty simple device.
It takes your 5 volt input and should give you + and - 12 volts out.
The important pins are all on the outside edge on the carrie.
 
Pin 1 and 2 are the USB power with 1 being +5 volts and 2 being USB ground.
 
Pins 5, 6 and 7 are the output voltages and are isolated from the input side.
Pin 5 is the amplifier ground, pin 6 is +12 volts and pin 7 is -12 volts.
 
When testing voltages, remember to reference to the correct ground.
 
If you are not getting the correct output voltages, check for shorts
in the voltage rails.
 
Apr 19, 2014 at 4:23 PM Post #880 of 913

Avro_Arrow

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I was just looking over the schematics and BOM for the Carrie.
It has some odd component choices.
 
The BOM specifies a dual rail version of the DCP01 even
though it only uses one of the output voltages.
A single rail DCP01 would have seemed to be a better choice...
 
If using a dual rail DCP01, it would seem to me to be a better
design to get rid of the TLE and extra op amp for the rail splitter
and just have a proper dual rail supply.
 
This is not aimed at anyone, I'm just rambling...
 
Edit: Oh, and lastly, it uses an 8 volt regulator giving +- 4 volt rails.
The op amps like 5 volt rails...
Why not a 10 volt reg or at least a 9 volt reg?
 
Apr 19, 2014 at 4:36 PM Post #881 of 913

KimLaroux

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  I was just looking over the schematics and BOM for the Carrie.
It has some odd component choices.
 
The BOM specifies a dual rail version of the DCP01 even
though it only uses one of the output voltages.
A single rail DCP01 would have seemed to be a better choice...
 
If using a dual rail DCP01, it would seem to me to be a better
design to get rid of the TLE and extra op amp for the rail splitter
and just have a proper dual rail supply.
 
This is not aimed at anyone, I'm just rambling...
 
Edit: Oh, and lastly, it uses an 8 volt regulator giving +- 4 volt rails.
The op amps like 5 volt rails...
Why not a 10 volt reg or at least a 9 volt reg?

 
Avro, what BOM are you looking at? Are you sure it's version 2.01?
 
I got the DCP010512BP, which is a single rail converter. The dual rail has model number DCP010512DBP. (it's in the datasheet)
 
I also got a TL750L10 that gives me a +-5 V supply for the op-amps.
 
Apr 19, 2014 at 4:53 PM Post #882 of 913

Avro_Arrow

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I was looking at the BOM here, mouser BOM
 
 
Your right...DBP is the dual rail version, BP is the single rail.
 
Disregard any reference to pin 7.
 
You should be getting 12 volts between pins 5 and 6.
 
Your component choices are correct.
 
May 2, 2014 at 6:26 PM Post #884 of 913

joneeboi

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Not your fault, Avro. That one's on me. 
smily_headphones1.gif

 
Jul 6, 2014 at 11:14 AM Post #885 of 913

patchoncas

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First time on Head-fi, because I can't seem to find this information anywhere.
 
Does anyone know where can I get one (possibly more) Carrie v2 boards? I have a AMB Mini3, and this Carrie amp interests me greatly!
I read through the whole thread, so my hopes are low (really low), but if someone has one and whishes to be charitable, I'm sure we can get along :)
 
Thanks anyway!
 

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