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JDS Labs C5/C5D (pg96) portable amp/amp+DAC - Page 104

post #1546 of 3342
Quote:
Originally Posted by Apo0th3karY View Post

Awwww no! Well this is a shame, but my wallet will thank me...

John, any time frame on when the revised C5D might be ready? I can bide my time no matter what - quality control is more important than my impatience - just crossing my fingers they'll be ready by mid January so I can get myself a birthday present.

And as much of a disappointment this news is, it'd be much more disappointing to have a 'flawed' product ship and potentially harm the products reputation

 

I'm guessing not, as he brought in some good minds to help troubleshoot.  They probably just need to isolate the issue, but since they may not know what the issue is yet it's anyone's guess how long it will take. :-/  But I think they're pretty smart, so.....

 

From a business standpoint I realize this probably seems like a horrible event, and John's stomach probably churned when he had to make the decision.  However, if others have had anywhere near the experience I have with JDS, this is just one of those "oh well, $%1t happens" situations.  JDS "is" the audio company to go to for extremely high quality, affordable gear.  I think more and more people are finding that out and hopefully this won't make any impression on people other than that they are doing the absolute best for the customer as always...  I know I think highly of their service and would always go their before anywhere else.

post #1547 of 3342
Well this is a huge bummer. I was stoked to receive my C5D tomorrow. Still am. Will listen for this "-80db hum"...
post #1548 of 3342
Quote:
Originally Posted by tvolpe1600 View Post

Well this is a huge bummer. I was stoked to receive my C5D tomorrow. Still am. Will listen for this "-80db hum"...

I'll be watching for your assessment very closely tomorrow smily_headphones1.gif
post #1549 of 3342
Quote:
Originally Posted by Apo0th3karY View Post

Awwww no! Well this is a shame, but my wallet will thank me...

John, any time frame on when the revised C5D might be ready? I can bide my time no matter what - quality control is more important than my impatience - just crossing my fingers they'll be ready by mid January so I can get myself a birthday present.

And as much of a disappointment this news is, it'd be much more disappointing to have a 'flawed' product ship and potentially harm the products reputation

 

Today we spent more time communicating the issue and driving boards across the state than actually troubleshooting. We've eliminated the PCM5102A and its two 3.3V LDO's as noise sources, meaning the noise originates somewhere within the SA9027 supply circuitry. A few more tests tomorrow will reveal which power rail(s) are affected, and then we'll be able to isolate the specific cause and implement a solution. In case it gets more complicated, we have some very bright engineering minds helping out.

 

I'm estimating 1-4 weeks, depending on severity of the fix. Once a fix is ready, our production shop can move swiftly.

 

Quote:

Originally Posted by luisdent View Post
 

 

From a business standpoint I realize this probably seems like a horrible event, and John's stomach probably churned when he had to make the decision.  However, if others have had anywhere near the experience I have with JDS, this is just one of those "oh well, $%1t happens" situations.  JDS "is" the audio company to go to for extremely high quality, affordable gear.  I think more and more people are finding that out and hopefully this won't make any impression on people other than that they are doing the absolute best for the customer as always...  I know I think highly of their service and would always go their before anywhere else.

 

The past five days have been a rollercoaster. Thank you all for your support.

 

Quote:
Originally Posted by tvolpe1600 View Post

Well this is a huge bummer. I was stoked to receive my C5D tomorrow. Still am. Will listen for this "-80db hum"...
 
 
In going through 30+ boards last night, the intensity varies from unit to unit. I found one much worse, which is good for troubleshooting...

Edited by jseaber - 11/13/13 at 9:41pm
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post #1550 of 3342
Quote:
Originally Posted by Spadge View Post
I'll be watching for your assessment very closely tomorrow smily_headphones1.gif

 

 

Quote:
Originally Posted by jseaber View Post

 

In going through 30+ boards last night, the intensity varies from unit to unit. I found one much worse, which is good for troubleshooting...

 

 

I almost wish I hadn't signed onto the forums tonight. Then I could report back a true blind test. Given the effort JDS is going through to fix the problem in a transparent and honorable manner, I hesitate to respond back at all. But John's response here only reinforced his total commitment to this product, so I'll do my best to report back what I hear on my unit.

 

I have everything ready to go for a thorough listening test when I get home from work. I have three platforms to run the C5D through its paces. For the combined amp and DAC, I will be using my (1) iPhone 5s with lossless files and (2) iMac / MacAir iOS rigs with Audirvana and hi res WAV files. On the pure amp side, I also just got a RCA to Mini from Blue Jeans Cable to hook the C5D up to my desktop DAC. Since the Firestone Tobby uses dual PCM1794s, I figured it would be an interesting comparison to the PCM5102As deployed in the C5D. John also noted there was no hum when using the analog input, so perhaps this is a good way to do blind A/B tests with the help of a friend.

 

I will be focusing on my HD650s to get a read on how dynamic cans sound, but I suspect it will be my old trusty Ultimate Ears IEMs that detect the hum.

 

Obviously, the crux of the issue for me is the whether the hum warrants a return. Stay tuned.

post #1551 of 3342

Update: Noise source has been identified. Pesky regulator doesn't like our plentiful 5V supply regulation. I've tamed this part before. Possible substitute parts will arrive Next Day Air tomorrow.

 

We'll know by this time tomorrow whether the fix is simple or complex.

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post #1552 of 3342

Thanks for rapid progress updates!

post #1553 of 3342

JDS: "The defect is a low level hum, below -80dB on most units (much quieter than a -60dB mute). Noise is entirely absent when operating only from the analog input, or when the DAC is paused or operating independently from the amp. Therefore, no one noticed all year."

 

I'm not surprised. I just spent the last three hours listening to my C5D in a number of configurations. Let me cut to the point. The defect on the C5D exists. But without knowing what to listen for, it might have taken me months to hear it. Why? I had to turn the volume all the way up in between tracks to hear the hum. Even then, it was barely noticeable on either of my dynamic cans (650s and AKG 702s), and was only an issue with IEMs at deafening volume. (Update: I'm not even sure this is the defect, which means I can't detect the hum all - this only strengthens my conclusions below.)

 

The odd thing is, John claims that noise is absent (1) "when operating only from the analog input" and (2) "when the DAC is paused." I can readily attest to the first claim. I fed the C5D an analog source through the 3.5 in, and heard no hum at all as I turned the volume to maximum. I did start to hear odd attenuation clicks at the last stages, though.

 

But I could only hear the hum when I paused the track and turned the amp volume all the way up. This is not a source / cable issue because I heard the same hum/distortion feeding the C5D DAC with digital streams from my iPhone5s (with CCK) and MacAir with Audirvana.

 

The crucial point is that I can't hear that hum at normal listening levels during playback. Does the hum still exist at the lower volume levels? I suppose. Does the defect require an immediate return? Most certainly not. The C5D sounds so spectacular that I am quite reluctant to part ways with it. Would it be nice if this unit was fixed at some point in the next few months? Yes indeed.

 

In sum, I can't emphasize enough that the defect is not a big deal. This only goes to underscore the total commitment to high quality that JDS is taking with the decision to cancel the roll out. I can only assume this decision had serious short term business ramifications. Based on the awesome music I've heard tonight through my 'defected' C5D, I do hope those ramifications turn out to be positive for JDS over the long run.

 

Back to listening ...


Edited by tvolpe1600 - 11/14/13 at 9:27pm
post #1554 of 3342
Quote:
Originally Posted by tvolpe1600 View Post
 

JDS: "The defect is a low level hum, below -80dB on most units (much quieter than a -60dB mute). Noise is entirely absent when operating only from the analog input, or when the DAC is paused or operating independently from the amp. Therefore, no one noticed all year."

 

I'm not surprised. I just spent the last three hours listening to my C5D in a number of configurations. Let me cut to the point. The defect on the C5D exists. But without knowing what to listen for, it might have taken me months to hear it. Why? I had to turn the volume all the way up in between tracks to hear the hum. Even then, it was barely noticeable on either of my dynamic cans (650s and AKG 702s), and was only an issue with IEMs at deafening volume.

 

The odd thing is, John claims that noise is absent (1) "when operating only from the analog input" and (2) "when the DAC is paused." I can readily attest to the first claim. I fed the C5D an analog source through the 3.5 in, and heard no hum at all as I turned the volume to maximum. I did start to hear odd attenuation clicks at the last stages, though.

 

But I could only hear the hum when I paused the track and turned the amp volume all the way up. This is not a source / cable issue because I heard the same hum/distortion feeding the C5D DAC with digital streams from my iPhone5s (with CCK) and MacAir with Audirvana.

 

The crucial point is that I can't hear that hum at normal listening levels during playback. Does the hum still exist at the lower volume levels? I suppose. Does the defect require an immediate return? Most certainly not. The C5D sounds so spectacular that I am quite reluctant to part ways with it. Would it be nice if this unit was fixed at some point in the next few months? Yes indeed.

 

In sum, I can't emphasize enough that the defect is not a big deal. This only goes to underscore the total commitment to high quality that JDS is taking with the decision to cancel the roll out. I can only assume this decision had serious short term business ramifications. Based on the awesome music I've heard tonight through my 'defected' C5D, I do hope those ramifications turn out to be positive for JDS over the long run.

 

Back to listening ...

 

This sounds like the c5.  No pun intended.

 

I talked to john once, and correct me if I'm wrong john, but when the amp is muted you might get some sort of noise at high volume, but when you're playing music you shouldn't.  It has something to do with the way the amp is designed.  At least I think that's what he said.  I also hear click at the highest attenuation stages, but under "most" circumstances you'd be hurting your hearing at those volume levels.  But in the rare instance of a quiet passage and a volume change at the same time you can hear small digital blippy clicks.  So I don't "think" those anomalies are problems with the c5d...  But I could be wrong.

post #1555 of 3342

Engineering has already identified and implemented a perfect solution. Parts arrive in the morning so that we can resume shipping promptly.

 

We'll provide an easy exchange for the handful of folks who have already received C5D's.

 

Look for an announcement in the morning.

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post #1556 of 3342

speedy. :-P

post #1557 of 3342
Wooly mammoth that was fast! Did you have to re-route components on the PCB or something? I remember having to do that because I accidentally grounded a through-hole component and had to re-order the PCB. XD
post #1558 of 3342
Quote:
Originally Posted by luisdent View Post
 So I don't "think" those anomalies are problems with the c5d...

 

I think you are probably right. I listened as hard as I could for any 'hums' or distortion, and could only find the high volume issues. So perhaps I could not detect the defect after all. This only strengthens my conclusion: the 'defected' C5D sounds great right now.

post #1559 of 3342
Quote:
Originally Posted by miceblue View Post

Wooly mammoth that was fast! Did you have to re-route components on the PCB or something? I remember having to do that because I accidentally grounded a through-hole component and had to re-order the PCB. XD

 

I'm sure it was fast from your point of view ;)

 

It took over 20 man-hours of measurement and dialogue between myself and two bright engineers, and much lost sleep. No drastic changes were necessary. Just one rail was thrown out of regulation due to the power hungry USB controller. We installed a significantly larger capacitor. The rail is now cleaner than ever.

 

The worst part is the drama this has caused. That, and we have lots of assembled C5D's to disassemble...

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post #1560 of 3342
I never knew who was John was before I bought my C5 but after reading this thread I have an even better impression of JDS Labs and what an awesome company it is. Just wanted to say that, its people like this guy that make Head-fi such a great community.
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