y1 gamma-1 DAC
Feb 17, 2009 at 11:12 PM Post #481 of 1,546
wait, you are saying you can phase invert the resultant analog out by manipulating bits directly at the spdif level, using 'only' gates? how many gates we talkin' about, here?
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what is the idea? read a value, find its complement, convert THAT to analog and output both at the same time?
 
Feb 18, 2009 at 2:36 AM Post #482 of 1,546
Hi All,

I've been a loooong time reader but never actually gotten round to breaking the silence...so here goes!
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I've been looking at making a DAC for some time now and have decided that the y1 looks like the way forward, I'm just wondering if anyone knows if you can get all the parts in the UK or if the PCB etc are only available from AMB? (I'm trying to keep the costs down on my maiden voyage if possible - if i can't then never mind!)

Basically I've got a pair of HD650s and decided the y1 looks like a good combination of price and performance - I want to make something which gives me a decent sound without going OTT on the price on my first attempt, I'd happily welcome anyones view on if this is a good starting point. ( I know there are simpler DACs to make, but Im not particularly worried about that aspect)

Thanks guys
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Feb 18, 2009 at 3:02 AM Post #484 of 1,546
Hi Royewest,

I've not done that much soldering etc in general for a good while, as for SMD stuff anything I did do was years ago (school!) so we may as well class me as a noob in that department.

I've got an amp, though it's far from exotic - an amp was actually next on my list of DIY stuff.

P.s. That was one fast reply!
 
Feb 18, 2009 at 4:05 AM Post #485 of 1,546
Quote:

Originally Posted by linuxworks /img/forum/go_quote.gif
wait, you are saying you can phase invert the resultant analog out by manipulating bits directly at the spdif level, using 'only' gates? how many gates we talkin' about, here?
wink.gif


what is the idea? read a value, find its complement, convert THAT to analog and output both at the same time?



Not by inverting SPDIF data, but rather the I²S data line. One gate is all you need if simple inversion is your goal. Data into one gate of an XOR, other gate to ground gives + output, or tie that gate to vcc to get - output. Use two XORs and you are able to get both polarity outputs with no real delay between phases. You could also use an (gasp) inverter, like 74hcu04 if you just want to swap polarity. Of course, this is all off topic for the Gamma1 thread, so back to your regularly scheduled program.
 
Mar 1, 2009 at 10:20 PM Post #486 of 1,546
Anyone have a spare SN74AHC1G02DBVR, Gamma 1 designated 'U8D' ?

I snapped one in half trying to remove it after accidentally soldering it in the wrong position.

If someone could drop one in the mail to me, I'll return the favor with some kind of surprise.
 
Mar 1, 2009 at 10:43 PM Post #488 of 1,546
Quote:

Originally Posted by MisterX /img/forum/go_quote.gif
Sure, send me the address info and I will drop one in the mail ASAP


MisterX to the rescue, using the most ridiculous postal methods for the smallest of items
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Mar 2, 2009 at 12:26 AM Post #490 of 1,546
Quote:

Originally Posted by rhys h /img/forum/go_quote.gif
MisterX to the rescue, using the most ridiculous postal methods for the smallest of items
darthsmile.gif




Refrigerator box
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(wouldn't matter to me if it's free!
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)
 
Mar 5, 2009 at 7:06 AM Post #491 of 1,546
I've noticed that the bass on my computer has been horrible, and I finally had time to look into it today. Recently I switched from the USB on my gamma-1 to SPDIF and I just made the realization today that that was the cause of my loss of bass. I'm talking significant, there is almost nothing below I'd guess 40hz. General bass is at least 4x clearer on USB mode. It seems like it used to be a bit better, but I can't say that for sure, it may have always been this bad. (Tested on two SPDIF sources). It sounds so nice on USB now!

But, I'd like to fix the spdif. Any thoughts what could cause this?
 
Mar 5, 2009 at 11:33 AM Post #492 of 1,546
I can't think of any reason why S/PDIF might have less or more bass than USB, if all software settings are the same. Check your media player software's EQ settings and disable them. Also, if you're running Windows, use ASIO4ALL to bypass the Windows kmixer.

You could verify the bass output by playing this 1KHz test tone as a reference, use your DMM's AC V mode to measure the DAC's output voltage. Then repeat this measurement with this 20Hz test tone. Do this with both S/PDIF and USB inputs. If the 1KHz voltage is the same as the 20Hz one, then you know there is no loss of bass.

Both files are WAV format, 0dBFS sine wave, mono, at 16b/48K. Download the files onto your hard disk to play them rather than playing directly in your browser.
 
Mar 5, 2009 at 2:16 PM Post #493 of 1,546
USB 1Khz = .783V
USB 20hz = .781V

SPDIF 1KHZ = .183V
SPDIF 20HZ = .293V

This was with the computer on the same volume, no change was made between tests except switching sound cards in control panel.

Perhaps the voltage is too low for the bass to really resonate? I don't know why it is lower than USB's voltage which likely creates a warmer sound being almost 4x higher on the bass. Also doesn't make sense that the SPDIFbass is higher voltage than treble
 
Mar 5, 2009 at 2:42 PM Post #494 of 1,546
dude_500, what computer and OS are you running, and what sound card provides the S/PDIF output? If it's Windows, are you running ASIO4ALL? Is there special control software for that sound card that has a "volume control" that digitally attenuates the S/PDIF audio stream? Since these files are recorded at 0dBFS, regardless of input, both files should produce about 1.5V-1.6V rms at the DAC's output (that is, if there is no mangling of the audio data such as digital attenuation of the volume). You should set all software volume controls to maximum.

What software are you using to play these files? Make sure that all effects plugins are disabled (such as equalizers, bass boost, crossfeed, whatever).

Your S/PDIF measurement shows that there is more bass than the midrange, which is opposite of your original report. This is still incorrect, but I suspect it's not a problem with the γ1, but rather a software settings issue. There is nothing in the γ1 that could cause this kind of bass anomaly, whether it's a boost or loss. The only exception is if you try to drive headphones with impedance less than 300 ohms directly without an amp, in which case the γ1's output coupling capacitors would form a high-pass filter and cause bass rolloff. But that shouldn't be the case here, since you're doing the measurements with nothing connected to the DAC output.
 
Mar 5, 2009 at 2:42 PM Post #495 of 1,546
Quote:

Recently I switched from the USB on my gamma-1 to SPDIF and I just made the realization today that that was the cause of my loss of bass.


Are you using the Optical or Coax input?
 

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