y1 gamma-1 DAC

[wushuliu]

Quote:

Originally Posted by amb /img/forum/go_quote.gif wushuliu, the two things are most likely separate problems. The LED not lighting up is probably due to a solder joint problem at U2D, U8D, Q1D, Q2D, R11D, R12D or R13D. For the crackly noise problem, try reflowing the solder joints at U3D. If that doesn't fix it, make sure your S/PDIF source is putting out a clean signal (i.e., no clipping) to begin with. Maybe it's a software configuration problem or simply a bad recording. Lastly, what are you using as your source and what is the rest of the audio chain downstream of the γ1?

Ok, I'll give a shot at reflowing solder joints. My source is direct from a WDTV optical out and downstream is a B1 buffer to Class D amp... I have other inputs going through the B1 and they work fine, so it's probably solder joints as youve said...

 

[wushuliu]

Out of curiosity, how would the Y1 compare against one of these?

Does the Y1 have the better design since it avoids opamps?

 

[wushuliu]

Quote:

Originally Posted by amb /img/forum/go_quote.gif jerry_c, I would recommend keeping γ1's output coupling caps, because without them, there will be a large DC offset (around 2.3V). I'm not sure the PGA2310 circuit would like to "see" so much DC at its input. At any rate it's best to block DC at its source rather than somewhere downstream. As for the SMD caps, if you could fit them on the through-hole pads and do a reasonable job of soldering them down (without touching/shorting to other parts), then sure. Why not.

Hi amb, I'm going to connect the y1 straight into a Pass B1 Buffer/preamp. The Pass presents a 1M load at input so presumably I can use much lower value output caps for the y1, correct?

 

[amb]

The Pass circuit might have a high input impedance, but does it not have a volume pot in front of it? That volume pot will essentially determine the real input impedance as seen by the source.

But anyway, yes, if you plan to drive highish-Z line loads, then you could use smaller coupling caps. You can work the math of how that affects the high-pass corner frequency.

 

[wushuliu]

Quote:

Originally Posted by amb /img/forum/go_quote.gif The Pass circuit might have a high input impedance, but does it not have a volume pot in front of it? That volume pot will essentially determine the real input impedance as seen by the source. But anyway, yes, if you plan to drive highish-Z line loads, then you could use smaller coupling caps. You can work the math of how that affects the high-pass corner frequency.

I believe the 25k pot comes after the 1M (at least on the schematic it does). thanks...

edit: never mind, yep, you're right.

 

[wushuliu]

Quote:

Originally Posted by amb /img/forum/go_quote.gif wushuliu, the two things are most likely separate problems. The LED not lighting up is probably due to a solder joint problem at U2D, U8D, Q1D, Q2D, R11D, R12D or R13D. For the crackly noise problem, try reflowing the solder joints at U3D. If that doesn't fix it, make sure your S/PDIF source is putting out a clean signal (i.e., no clipping) to begin with. Maybe it's a software configuration problem or simply a bad recording. Lastly, what are you using as your source and what is the rest of the audio chain downstream of the γ1?

Hi amb, I resolved the led issue. However, the crackle is still present. Actually it isn't so much a crackle as very rapid drop-outs in sound. Also, the LED actually flickers between red and green rapidly along w/ the dropouts as well. Is it possible the toslink receiver is damaged? I reflowed joints and did continuity tests across most of the board and all was ok. I tested the cable elsewheres and it was fine as well...

 

[amb]

Maybe it's a problem with the source (what are you using as you source anyway)? Try a different source and use the other inputs too, to see if you could find any pattern to this. That should help isolate the problem. Also try different cables.

 

[ZeNmAc]

Hey guys, I've been meaning to build one of these soon, but I'm not really sure which parts to order. The website has good instructions, but I'm wondering if there is any difference between the caps or other components I use. Is there a difference, or should I just get the cheapest ones? (I'd appreciate recommendations too)

 

[amb]

ZeNmAc, your question is too generic. Some parts should not be substituted (or at least, be substituted only with something of very similar specs), while others are "your choice" given the size/fitment constraints. The parts list shows all the recommended parts and their alternatives, and provide some details about them.

"Getting the cheapest ones" is not always a good plan when you're talking about a total difference of a few dollars or less.

 

[FunkyGibbon]

Hi,

It was previously mentioned that the 1uF multilayer capacitor (Farnell 1200404) is quite expensive at Farnell AUS. The SMD version was raised as a possible substitute.

I have found these other 1uF multilayer ceramic capacitors at Farnell. All are X7R-type, all have physical dimensions equal to or smaller than the specified one, all have capacitance tolerance of 10%, and all have lead spacing of 5mm, as per the specified one. All cost at least three-times less than the specified one at Farnell.

Farnell:
1650921
1650918
1604727
287064

Are there any factors I've overlooked here, or are these all suitable substitutes? (Yes, I know they're all a lot less pretty than the EPCOS one!!).

Thanks for your help,

Christopher

 

[MisterX]

From the image it looks # 1600878 could be a nice option but it's out of stock in Australia.
# 1600879 is similar but it has a "Y5V" dialectic.
But....No datasheet?

I would either go with # 1186182 and bend the leads to fit or make use of the "special order service" that is offered on the top of the AMB audio shop order page.

 

[jarpatus]

Hi,

Just quick stupid question, did not find answer using search... If I choose to drive headphones directly, should I change C22D also to 470uF? Can't decide from description in parts list... Looking at shcematics, I would say that I do not need to change it, only C24D and C25D, but then again, while I can read schematics easily, it is much harder to understand them

Thanks!

- J

 

[MisterX]

Quote:

should I change C22D also to 470uF?

No.

 

[FunkyGibbon]

Hi MisterX,

Thanks for your reply.

Regarding the capacitor Farnell # 1186182, it is 3.8mm wide, while the specified cap is 2.5mm wide. While this will not be a problem for C1D, C21D, and C2U, as they appear to have plenty of room, C10U looks a little tight. Do you think 3.8mm wide will be okay?

Thanks again,

Christopher

 

[wz2000]

I just completed my build of the y1. But I'm having some weird grounding issues I think.
Sometimes the y1 sounds very clean. But if I move the case I sometimes start hearing a slight hiss in the signal. This also happens if I move the selector from the USB position(I mostly use the USB mode). I know this should be normal if there's nothing connected to the other inputs, but the hiss then stays if I switch back to USB. Anyone know how to fix this? It passes the checks listed on Ambs site.

It sounds great when it works, but the hiss keeps coming back too often.

Thanks in advance.