Figuring out the HRT Music Streamer II (Rev. 5) - diyAudio
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Old 10th May 2011, 09:17 PM   #1
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Default Figuring out the HRT Music Streamer II (Rev. 5)

Hello all

I'm starting to become interested in DACs and how they work, especially asynchronous USB DACs.

I recently bought a HRT Music Streamer II, and I'm really curious to figure out how exactly it works. I've taken some fairly high resolution pictures of the PCB, both front and back. I've then succeeded in superimposing the traces from the back of the PCB onto the front picture of the PCB, so I can see where connections go between the components. I'm attaching this picture here, the semi-transparent red lines are the traces from the back of the board.

One thing I can't seem to figure out is where the clock is, is it the one marked "C AA7Z 6.000M"? I can't find anything searching Google for this.
I know the TAS1020B chip is the chip responsible for the asynchronous USB trasnfer, and I can see that the chip marked "24C64WP" is some kind of ROM, do you think this is where the firmware for the TAS1020B chip resides?

I'm basically just curious to learn more about digital to analog design, and I figured this would be a place to start.

Cheers!

-Rune
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Old 10th May 2011, 09:30 PM   #2
ojg is offline ojg
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Quote:
Originally Posted by runeks View Post
One thing I can't seem to figure out is where the clock is, is it the one marked "C AA7Z 6.000M"?
Yes
Quote:
Originally Posted by runeks View Post
I can see that the chip marked "24C64WP" is some kind of ROM, do you think this is where the firmware for the TAS1020B chip resides?
Yes

Thanks for posting the picture, always interesting to see. The output opamp is one of the cheapest ones they could possible find, replace it with a NE5532 and it will be 100 times better
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Old 10th May 2011, 09:50 PM   #3
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Would you happen to have a link to the datasheet of the clock? I can't find anything searching for that string. Also, do you know what the 6.000M refers to? Certainly not 6.000MHz, right? I figure that'd be useless for 44.1kHz to 96kHz.
Do you think I would gain anything from replacing the clock with something else?

This is a $150 DAC, so I'm not surprised it's a cheap op-amp, would be interesting to switch it out though, I can probably afford the $1 , although I've never done anything like that before.
They have a more expensive version called the "Music Streamer II +", too bad I can't find a higher resolution image of that so I can see which op-amp is on that board. There's a low-res image here, but I can't tell much from that picture: The HRT Music Streamer II: Asynchronous 24/96 for $149.95! | Headfonia

All I can see is that the Plus-board contains a lot less capacitors and resistors, how can this be? What replaces them? Why can't they be avoided on the cheaper board? I assume it's desirable that the analog audio go through as few components as possible.

EDIT: Found a somewhat higher resolution picture of the Plus-version: http://www.alpha-audio.nl/wordpress/...I-Plus-Dac.jpg
Looks like it uses the TI 2132UA op-amp.

Last edited by runeks; 10th May 2011 at 09:56 PM.
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Old 11th May 2011, 11:03 AM   #4
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On closer inspection, it looks like the Streamer II Plus uses four NE5534AD op-amps. At least I can see that there are four chips in the output stage with the text 5534A on them, followed by the 2132UA op-amp: http://www.alpha-audio.nl/wordpress/...I-Plus-Dac.jpg

Can anyone elaborate on why it uses first four NE5534AD op-amps followed by a single 2132UA op-amp? Why not just a single one?

Cheers!
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Old 15th May 2011, 03:16 AM   #6
Arius is offline Arius  United States
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I'll try and answer Runek's questions...

1) The 6.000 is a 6.000MHz crystal oscillator. It doesn't matter what digital audio bit rate the processor supports. The TAS1020 is a microprocessor, it needs a clock in order to perform its work. Don't bother searching for a datasheet - it's a generic SMD crystal, most likely of the 20-50ppm type. See Epson MC-156 series as an example.

2) The Streamer II Plus has 4 NE5534's because it uses the PCM1794. The PCM1793 is fully integrated and generates an analog output signal, so a simple buffer is all that is required. The PCM1794 requires an external IV (current-to-voltage) stage and that's takes 2 NE5534's for each channel.

Have fun...
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Old 31st May 2011, 06:31 AM   #7
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Anyone tried swap out the M33078 with a NE5532?

I can find a NE5534AN. Will this suitable?

Or a OPA2134PA also suitable?
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Old 31st May 2011, 12:51 PM   #8
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Quote:
Originally Posted by marce View Post
Your starters, mainly layout based cos that is what [...]
Thanks marce! That's a lot of documents, I guess I won't run out of reading material in the near future.
I hope it's not over my head; that the technical level isn't too high. But thanks a lot for taking the time to post these.

Quote:
Originally Posted by Arius View Post
I'll try and answer Runek's questions...
[...]
Thanks Arius, good explanations. Wrt. to the 6 MHz clock, I guess I was just looking for the clock for the output stage, so the 6 MHz didn't make sense, but now I understand.

I'm considering buying the Streamer II Plus as well, and taking some good pictures of this too. I'll post them here if I do. It seems to me that if the design is both simpler and higher quality in the II Plus vs. the (standard) II (the II Plus looks a lot simpler at least), starting with the Plus version is a better idea for a beginner like me.

Cheers!
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Old 1st June 2011, 05:20 PM   #9
hajj is offline hajj  Lebanon
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runeks, thanks for the pics.
This is getting interesting as I have that same DAC and being a relative noob to the tweaking world, am very interested in seeing if any easy mods are possible on that DAC, especially the op-amp...
Will be following the thread closely, hope it develops further.
Regards
Nick

Last edited by hajj; 1st June 2011 at 05:24 PM.
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Old 25th March 2013, 10:50 PM   #10
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In case anyone finds it useful, here is a link to a zip containing all the pictures I took of the device. I don't have it any longer, but I got a PM from someone who had some questions, and I figured a picture of the back of the board might be useful to some. And then when I'm at it anyway, I might as well make all the pictures available, so you can work with all the information available that I have.

Here's the link: http://runeks.dk/files/hrt-music-str...-rev5-full.zip
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