[electropop]

Thanks lessie.. Can i call you lessie..?

Good to know there's not that much difference between them used as DAC's. Usually i tend to hear it right away, if something's quite different. I'll be receiving my zero soon, so indeed, good to know

The remote sure is tempting though ...

-K

 

[les_garten]

Quote:

Originally Posted by electropop /img/forum/go_quote.gif Thanks lessie.. Can i call you lessie..?

Sure, reminds me of ol' times. I haven't been called that since 4th grade when I re-arranged that kid's face!

 

[electropop]

Hahhah!

Cool that you're cool with it

 

[freak]

jsplice

Describe what mods you apply on your Yulong after you do this.
I was thinking of changing opamps to 2x opa2604 and 1x ad8022 (this set was recommended for Prodigy HD2), but I'm not sure if that is going to work properly with Yulong.

 

[les_garten]

Quote:

Originally Posted by freak /img/forum/go_quote.gif jsplice Describe what mods you apply on your Yulong after you do this. I was thinking of changing opamps to 2x opa2604 and 1x ad8022 (this set was recommended for Prodigy HD2), but I'm not sure if that is going to work properly with Yulong.

Can't wait to hear the results....

 

[Cecala]

Quote:

Originally Posted by jsplice /img/forum/go_quote.gif Did you notice any improvement in sound quality when you insulated the transformer? I'm going to go out this evening and see if I pick up some felt. The tire suggestion might work also, or maybe I can even find some other type of rubber material at the hardware store that I can use.

Jsplice, I didn't mod my player, that's how it came from the manufacturer. The reason I think they use felt over rubber is that rubber reduces overall 'rocking' or movement while felt deadens vibrations over a given sound spectrum, below 100Hz.

 

[iainw]

ARGH!

How do I get rid of the hiss/hum?

Is only noticeable with high sensitivity headphones (ATH w5000) and hardly noticeable with others such as the DT770pros but is very very annoying!

 

[jsplice]

Quote:

Originally Posted by iainw /img/forum/go_quote.gif ARGH! How do I get rid of the hiss/hum? Is only noticeable with high sensitivity headphones (ATH w5000) and hardly noticeable with others such as the DT770pros but is very very annoying!

Welcome to my world (when I try to use it as a preamp in my stereo). It sounds great when I use the DACOUT jacks into my other preamp.

If you put your ear right against the DAC, can you hear the transformer humming? I'm not sure if that's what's causing the humm/hiss, but it has been my suspicion the whole time.

 

[les_garten]

Quote:

Originally Posted by jsplice /img/forum/go_quote.gif Welcome to my world (when I try to use it as a preamp in my stereo). It sounds great when I use the DACOUT jacks into my other preamp. If you put your ear right against the DAC, can you hear the transformer humming? I'm not sure if that's what's causing the humm/hiss, but it has been my suspicion the whole time.

Hi,
I used a Cardiologists stethoscope on my case and "barely" hear a 60 cycle hum.

 

[jsplice]

Quote:

Originally Posted by les_garten /img/forum/go_quote.gif Hi, I used a Cardiologists stethoscope on my case and "barely" hear a 60 cycle hum.

I can hear it loud and clear when I have my ear a few inches from the case. I've plugged the unit in at several different locations, and it always hums at the same loudness. So it's not a power issue. I also have a PS Audio UPC 200 that it plugs into.

 

[les_garten]

Quote:

Originally Posted by jsplice /img/forum/go_quote.gif I can hear it loud and clear when I have my ear a few inches from the case. I've plugged the unit in at several different locations, and it always hums at the same loudness. So it's not a power issue. I also have a PS Audio UPC 200 that it plugs into.

Sounds like a problem, or you're half canine!

 

[les_garten]

Quote:

Originally Posted by jsplice /img/forum/go_quote.gif I can hear it loud and clear when I have my ear a few inches from the case. I've plugged the unit in at several different locations, and it always hums at the same loudness. So it's not a power issue. I also have a PS Audio UPC 200 that it plugs into.

Sounds like a problem, or you're half canine!

 

[Cecala]

Jsplice, did you end up inserting either felt or rubber between case and transformer and if yes, any improvements?

 

[jsplice]

Quote:

Originally Posted by Cecala /img/forum/go_quote.gif Jsplice, did you end up inserting either felt or rubber between case and transformer and if yes, any improvements?

I did put rubber foam weather stripping between the transformer and the side of the case, and it did nothing. I've been researching this issue all over the Internet, and people are saying that DC in the AC power lines can be a cause of transformer hum. I'm not positive as to whether or not the humming transformer is the cause of a loud buzz through my speakers when using the dac in preamp mode, but I do suspect that to be the cause. There are several commercial DC filtering products, such as the PS Audio Humbuster, UPC 200HB (I actually own the normal PS Audio UPC 200, which has no humbusting capabilities), and Channel Islands Audio also makes a DC filtering product. There are a few DIY DC filtering projects I've seen online as well.

I emailed the seller on ebay about this issue, and doesn't seem to think it's a transformer issue, but rather it's an issue with impedance matching between the DAC and my power amps. I don't believe that to be the case, and if it were the case, then this is a serious design flaw. The NAD C272 power amps are a widely used commercial product, and I'm sure their input impedance is well within the acceptable level.

 

[iainw]

So no one has been able to get rid of it? Should I just chuck in the bin? What are people buying instead because it seemed like a good solution?