[amb]

Quote:

Originally Posted by thoppa /img/forum/go_quote.gif Can I ask you about the y1 ? The CS8416 datasheet suggests this RFLT CFLT CRIP 23kΩ 22nF 1nF

I don't know which datasheet you're looking at, but The CS8416 datasheet at Cirrus Logic Home Page, on page 54, Table 6, recommends Rfilt=3KΩ, Cfilt=22nF, Crip=1nF for any sampling rate between 32KHz and 192KHz.

Quote:

On the y1 the components are C18D, C19D and R4; 3kΩ 33nF 1nF

Yes, so the only difference is Cfilt. I don't really remember why we chose 33nF instead of 22nF, but I didn't observe anything bad from this. If you want, you could use 22nF.

 

[thoppa]

Quote:

Originally Posted by amb /img/forum/go_quote.gif I don't really remember why we chose 33nF instead of 22nF, but I didn't observe anything bad from this. If you want, you could use 22nF.

My bad on the component value - must be the drugs...wearing off....

I assumed you had chosen a different value because the y1 is limited to 96Khz ? I'm guessing that increasing the value of cfilt will increase the settling time, which would make it harder to lock onto a 192khz signal but perhaps would reduce jitter for 96Khz and below ? What do you think ?

Thanks !

 

[amb]

I have no trouble getting the CS8416 to lock on a 192KHz stream via either the coax or optical inputs, even though γ1's WM8501 DAC as configured (256*fs) could only support up to 96KHz. But on the γ2 the ASRC will happily accept the 192KHz stream (and downconvert to 96KHz) before sending it to the WM874x DAC.

EDIT: I should add that SRC4192 in the γ2 will support 192KHz but AD1896 won't. This is due to the 256*fs master clock configuration.

 

[morks]

Just wanted to chime in and say that my Gamma2 is alive and kicking. Thanks amb! Now I only have to find good music.

Although, could you please say somewhere on the Gamma2 site that for the G2 to work with the G1 D config (and others?), you need more parts than what its' parts list suggests (see MisterX' post somwhere in this thread)? Beginners like me would appreciate it. I wondered why it didn't work at first until someone pointed out to me that the G2 board wasn't getting any power because there was no connection from the USB power line to the G2. Good thing I randomly ordered more parts from you than I thought I needed

 

[thoppa]

Quote:

Originally Posted by amb /img/forum/go_quote.gif I have no trouble getting the CS8416 to lock on a 192KHz stream via either the coax or optical inputs, even though γ1's WM8501 DAC as configured (256*fs) could only support up to 96KHz. But on the γ2 the ASRC will happily accept the 192KHz stream (and downconvert to 96KHz) before sending it to the WM874x DAC. EDIT: I should add that SRC4192 in the γ2 will support 192KHz but AD1896 won't. This is due to the 256*fs master clock configuration.

So if it doesn't affect lock-on, then I could increase cfilt to reduce jitter further ? Did you try any other values ?

 

[Draguljce]

Although, could you please say somewhere on the Gamma2 site that for the G2 to work with the G1 D config (and others?), you need more parts than what its' parts list suggests (see MisterX' post somwhere in this thread)? Beginners like me would appreciate it. I wondered why it didn't work at first until someone pointed out to me that the G2 board wasn't getting any power because there was no connection from the USB power line to the G2.

Can you be more precise ? I build gamma 1 D-config but still waiting for SRC4192 for gamma 2

 

[amb]

Quote:

Originally Posted by morks /img/forum/go_quote.gif Although, could you please say somewhere on the Gamma2 site that for the G2 to work with the G1 D config (and others?), you need more parts than what its' parts list suggests (see MisterX' post somwhere in this thread)? Beginners like me would appreciate it. I wondered why it didn't work at first until someone pointed out to me that the G2 board wasn't getting any power because there was no connection from the USB power line to the G2. Good thing I randomly ordered more parts from you than I thought I needed

What more parts did you need? The parts lists on the websites should be correct.
As for the connection from USB power line to the γ2 (with γ1 "D" config), you don't need more parts. All you need to do is to solder a wire to bridge the VBUS and VCC lines on the γ1 board.

 

[ShinyFalcon]

I think I'm experiencing some deja vu here... I saw your post yesterday, or am I imagining things?

Anyways, the y1 pages does list a table of jumper settings, and for configuration D (USB-> I2S) it does states in notes, "also short J2U pins 1 and 2," which connects USB's 5V (VBUS) to VCC.

Are you stuck on something? If you are not using the SRC4192 then you will have to jumper (use straight resistor clippings) four pins on y2's JP2. This connects the I2S line from y1's USB board directly to the WM8741 DAC. When you install the SRC4192, you have to remove those jumpers.

 

[Nebby]

I think he was quoting morks' post in the previous page, but didn't use the quote function.

 

[Draguljce]

Quote:

Originally Posted by Nebby /img/forum/go_quote.gif I think he was quoting morks' post in the previous page, but didn't use the quote function.

True. I'm quite sure that i pressed (quote - reply with quote)

BTW. I just went trough all instructions and inspected boards and can't find any problems, VBUS and VCC are bridged by JP2D pins 2 and 3 (or U1D) and connected via gamma2 board back to J2U thus providing power for both boards.

I didn't begin building gamma2 as I'm still waiting for SRC, so for now I'm only watching this thread

Gamma1 D-config is live and kicking.

 

[CodeToad]

I made a BOM/Worksheet to build a Y1-D config USB Only Gamma2. It is hard wired to run on wall power...NO USB POWER in the BOM so adjust accordingly if you want to run regular unleaded in your Formula1 car

Use the Combined BOM to buy the parts and use the "Print Worksheet" to build each board.

Start with the Y1 "Print Worksheet" (print it out and mark off each step as you go) and follow it top to bottom...all the parts are in the order they need to be installed and the jumpers are already figured out. Notes give you tips so you don't have to learn the hard way.

Repeat for Y2.

If you find mistakes please let me know so I can fix it.

This will net you a Gamma2 with a nice green LED on the front panel and usb input only and powered by wall power only.

 

[MisterX]

Quote:

Because the size of the caps affects the corner frequency...sometimes changing it can be detrimental, I thought.

Bass ackwards, assuming the load is unchanged increasing the capacitance lowers the corner frequency of the filter.


Quote:

Haven't tried it without the bypass caps - have you?

Of couse I have tried it.


Quote:

Is it worthwhile?

Yes but I am not a fan of using the Wima MKS2 series as coupling caps so...

 

[MisterX]

Quote:

If you mean to keep the coupling caps and not use the additional bypass, then this would result in the loss of some detail and a slightly rougher top end. How much worse would depend on the quality of the electrolytics - BG NX Hi-Q are great so it'd only be a small difference. I think MrX is having an evil day....

Not even close..... but if I was I would tell you an implication that all film capacitors have the same sonic effect in that position is ridiculous.

 

[K3cT]

Quote:

Originally Posted by JamesL /img/forum/go_quote.gif I said they'd be satisfactory with higher impedance cans when they are being driven directly out of the DAC. I think amb's default recommendation of 470uF KW's are generally better suited for driving headphones directly out of the DAC though.

I see. So you're talking about in the context of driving it straight from the DAC. Thanks, man.

The latest talk of the choice of bypass film caps is interesting. Do you guys think there is a merit of changing these Wima caps from MKS2 to MKP2? It seems that there is a common belief that polypropylene > polyester.

The only drawback I can see is size though Ti's γ2 site mentions that you can go lower with these bypass caps. Is there a limit on how low in capacitance you can go before things become detrimental?

 

[amb]

Quote:

Originally Posted by K3cT /img/forum/go_quote.gif The only drawback I can see is size though Ti's γ2 site mentions that you can go lower with these bypass caps. Is there a limit on how low in capacitance you can go before things become detrimental?

You can do the math yourself. The corner frequency is:

fc = 1 / (2 * pi * R * C)

where,
R = the load impedance in ohms
C = The coupling capacitance in Farads (you need to apply 10^-6 for uF)
pi = 3.1416

I would like fc < 10Hz, maybe 5Hz if feasible.

For example, if you are planning to drive a 10K ohm load (i.e., the input of Mini³ amp), and you use a 1uF MKS cap only, plugging the numbers into the formula gets you fc = ~16Hz. I would be happier with a 2.2uF or 3.3uF instead which will drop fc down to ~7Hz or ~5Hz, respectively.

On the other hand, if you plan to drive 32 ohm headphones directly out of the DAC, you'll need hundreds of uF to attain the goal. 470uF will get you fc = ~11Hz.