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JDS Labs C5/C5D (pg96) portable amp/amp+DAC - Page 83

post #1231 of 3340
I have a c5 and I'm loving it with my beyer dt770AE phones. However, I'm considering getting a pair of Hifiman he-400s. Will the c5 be powerful enough to power the 400s?
post #1232 of 3340

I wanted to chime in here and report a bit after a billion hours (exaggeration) of using my C5.  First, so far it has improved everything I've connect to it at least to some degree.  It works extremely well with most phones I've tried with it, however, I've started noticing a bit of a lack of power for some music when using my er4s which are 100ohm.

 

I use it in high gain mode, and I can give it the full volume of my source players (zip clip, fuze v2, ipod touch, ipod class, apogee duet, etc.) It doesn't seem to matter which device I give it, I've been finding a lot of quieter music lately requires the max output on high gain to get an "almost" good volume.  This isn't all the time, but there are definitely songs such as a lot of soundtrack music with quiet soft orchestration or piano.

 

I'm having a hard time writing this, because I don't want to say anything negative about it! haha.  But I wish it had just a little more power.  It is a very silent amp, however, I don't recommend running it past, say, 90% volume for two reasons.  First, there is noise with the amp itself. I've tested with a perfectly silent file as well as simply full volume disconnected.  This only shows at the highest volumes, which would probably make you deaf with most IEMs.  However, with something like the er4s you will get audible noise when listening to already quiet soundtrack music at max volume.  Second, the volume control starts to make a much more noticeable and annoying sound when you press it as you get close to max volume.

 

I'm only saying this for those who might listen to a lot of music like me and might find it isn't really powerful enough for something not as sensitive like the er4s.  I wish it had another 10-20% power output and it would be great for the er4s, because it's such a reference grade amp in sound quality.  Anyhow...  Still an amazing amp for the price/size, and I recommend it over most other amps if raw power isn't the only concern.  It's still very powerful and handles most iems, including the er4s in "most" situations with ease....

post #1233 of 3340
I'm not sure what your volume settings are but:

Sansa Clip Zip (Rockbox 0 dB volume and/or stock firmware, high volume setting, maximum volume)
FiiO L2
C5 (low-gain, volume 25 steps after mute, or 26/63)
AKG K 701 (which is one of the more inefficient dynamic headphones out there)

I'm using a self-recorded binaural recording, which is quite quiet to being with, and it sounds plenty loud to me.
https://dl.dropboxusercontent.com/u/2816447/2013-07-12_-_Binaural_Access_Badge.wav (~27 MB)
^ that's the raw, unaltered audio recording (this is just a sample of the longer recording to keep the file size small-ish)
Edited by miceblue - 8/8/13 at 1:29am
post #1234 of 3340
Quote:
Originally Posted by miceblue View Post

I'm not sure what your volume settings are but:

Sansa Clip Zip (Rockbox 0 dB volume and/or stock firmware, high volume setting, maximum volume)
FiiO L2
C5 (low-gain, volume 25 steps after mute, or 26/63)
AKG K 701 (which is one of the more inefficient dynamic headphones out there)

I'm using a self-recorded binaural recording, which is quite quiet to being with, and it sounds plenty loud to me.
https://dl.dropboxusercontent.com/u/2816447/2013-07-12_-_Binaural_Access_Badge.wav (~27 MB)
^ that's the raw, unaltered audio recording (this is just a sample of the longer recording to keep the file size small-ish)

 

Yeah, I have quieter songs than that.  The problem is also that even though it's loud enough on some quiet songs, the song pushes it to the limit where this is a bit of noise and loud volume change noises.  But in fairness, this is probably about 4% of my music.

post #1235 of 3340
Quote:
Originally Posted by luisdent View Post

 

Yeah, I have quieter songs than that.  The problem is also that even though it's loud enough on some quiet songs, the song pushes it to the limit where this is a bit of noise and loud volume change noises.  But in fairness, this is probably about 4% of my music.

 

If your music is so quiet that you must turn the volume near max, then the recording itself is responsible for generating background noise and that should be present with any amp. C5's volume control features zero-crossing detection, which basically eliminates switching noise as long as there's an active audio signal. If the music is exceptionally quiet, it's challenging for zero-crossing detection to work, and thus, you may hear a slight click during large volume transitions at high volumes. So the "4%" of music figure you quite sound accurate. Personally, I've never run into these issues. Volume is always below 70% for my personal library and various headphones.

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post #1236 of 3340
Quote:
Originally Posted by jseaber View Post

If your music is so quiet that you must turn the volume near max, then the recording itself is responsible for generating background noise and that should be present with any amp. C5's volume control features zero-crossing detection, which basically eliminates switching noise as long as there's an active audio signal. If the music is exceptionally quiet, it's challenging for zero-crossing detection to work, and thus, you may hear a slight click during large volume transitions at high volumes. So the "4%" of music figure you quite sound accurate. Personally, I've never run into these issues. Volume is always below 70% for my personal library and various headphones.
It is almost all of the time for me too. But it's not switching noises or anything i'm hearing. I put a digitally silent audio file i made on my ipod and sansa and mac with interface. Played the silent file at the same volume i listen to a really quiet song at and there is clealy audible noise. But again, at or near max volume. I'm not saying it's common. It's not. But there are some classical songs and soundtrack music that pushes the c5 to it's limit. That's all. Plus with any player, if you use any eq, you need to cut the gain via eq app to prevent clipping. This makes it worse. But i would bet most people never even hear it. Just saying... I have music on cds that is quiet enough for me to max the c5 and have it no be loud. At this volume using the volume knob gets loud too.

If the c5 switches when no audio is detected then mine is broken ;-) my digitally silenced file plays continuous noise at or near max volume. If i understood you correctly...
Edited by luisdent - 8/8/13 at 6:19pm
post #1237 of 3340
I now have my C5. It's a stunning piece of equipment. The finish is superb and I love the contrast with red and black. I took a photo, but I don't think it does it justice as to how the color and sheen show in the light.
 
It sounds excellent. I love the bass boost with some of my music. I had mine set to a 3db boost which is plenty. I also appreciate the fine volume control and that I don't need to reset it each time I turn it on.
 
I just don't know if I can appreciate the sound quality improvement over the direct output from my iPhone 5. I haven't yet spent hours listening to the same music with and without the C5. So far, I've compared a number of uncompressed music files with an A/B selector. I have the line out from the iPod Touch 5 (through Apple's lightning adapter) connected to the C5 on A and the headphone out of the iPhone 5 on B. I set the sound of each to the exact same volume and I start both players at the same time, so when I switch sources, there's no detectable change, except for any differences in sound quality. So far, I don't hear any significant difference. I've tried with both the Sennheiser HD598 headphones and with the Westone 4R earphones. Both are very sensitive and low impedance at 103db/32ohm and 118db/31ohm. Is it possible that for these phones, an amp is just not going to make much of a difference? Has anyone else heard a significant improvement with either of the HD598 or 4R? I'll spend more time listening without switching and see if I enjoy listening more with C5.
 

 

 

 

post #1238 of 3340
Quote:
Originally Posted by Phredd View Post

I now have my C5. It's a stunning piece of equipment. The finish is superb and I love the contrast with red and black. I took a photo, but I don't think it does it justice as to how the color and sheen show in the light.
 
It sounds excellent. I love the bass boost with some of my music. I had mine set to a 3db boost which is plenty. I also appreciate the fine volume control and that I don't need to reset it each time I turn it on.
 
I just don't know if I can appreciate the sound quality improvement over the direct output from my iPhone 5. I haven't yet spent hours listening to the same music with and without the C5. So far, I've compared a number of uncompressed music files with an A/B selector. I have the line out from the iPod Touch 5 (through Apple's lightning adapter) connected to the C5 on A and the headphone out of the iPhone 5 on B. I set the sound of each to the exact same volume and I start both players at the same time, so when I switch sources, there's no detectable change, except for any differences in sound quality. So far, I don't hear any significant difference. I've tried with both the Sennheiser HD598 headphones and with the Westone 4R earphones. Both are very sensitive and low impedance at 103db/32ohm and 118db/31ohm. Is it possible that for these phones, an amp is just not going to make much of a difference? Has anyone else heard a significant improvement with either of the HD598 or 4R? I'll spend more time listening without switching and see if I enjoy listening more with C5.
 

 

 

 

 

Significant, no.  But a difference yes.  I'm not sure what music you listen to, but I can give you some song examples that show a clear difference between at least the ipod touch 5g line out and headphone out...  

post #1239 of 3340
Quote:
Originally Posted by luisdent View Post

 

Significant, no.  But a difference yes.  I'm not sure what music you listen to, but I can give you some song examples that show a clear difference between at least the ipod touch 5g line out and headphone out...  

 

That would be be great! I don't yet have all my music imported lossless, but if you can recommend some good songs for comparison, I'll reimport them. I like classical and I listened to two recordings of the last movement of Beethoven's 9th. They were lossless, but old recordings. I love Pink Floyd, Santana, The Who, The Beatles, the Stones, Beethoven, Brahms, Mozart, Yes, Steve Miller, Chicago, Mariah Carey, John Mayer, Jason Mraz just to give you an idea. I have tons more and would even be willing to buy a CD or two. I'd like to be convinced, because I know that even if it's difficult to hear a big difference with A/B testing, a better sound will make long term listening more enjoyable.

 

Thanks fellow New Hampster!

post #1240 of 3340

The first thing that pops in my head, as I was just talking about it, is "the wedding" from deep impact by james horner.  Here's a sample of the part I can easily hear the difference with:

https://dl.dropboxusercontent.com/u/48137075/06%20The%20Wedding.mp3

 

After the soft part with the flute the strings come in.  On the 5g touch headphone output the strings have a strange tone.  The C5 makes them sound correct and even.

post #1241 of 3340
I'm not sure about the iPhone 5, but I own the previous 4S and the difference is pretty subtle, but noticeable to me. Most of the differences are in the way instruments are separated in my head, with the C5 being much more spacious and instruments are better-defined. The other difference I've noted is that the treble becomes less grainy and more defined, again, compared to the headphone out jack.
post #1242 of 3340

The ipod touch 5g specifically has a worse headphone output.  I don't care what anyone or measurement says, there's something odd about the high frequencies or at least the way they're presented.  If you have one and a c5, just listen to that with headphone output and then line out to the c5.  Double amping the headphone output doesn't get rid of it.  The line out sounds like a fuze or clip+ or any other reference grade output.  The 5G headphone out has the issue...  It's not great, but it's more noticeable to me than the classic or ipad or three different nanos.  They are all critically similar,  but the 5G is off somehow.  Listen to the strings that build in that song and they just sound strange from the headphone output.  This might be more noticeable on certain earphones.  I'm using the er4s and pfe112, which neither has any issue with the other devices I mentioned.

post #1243 of 3340
Quote:
Originally Posted by luisdent View Post


It is almost all of the time for me too. But it's not switching noises or anything i'm hearing. I put a digitally silent audio file i made on my ipod and sansa and mac with interface. Played the silent file at the same volume i listen to a really quiet song at and there is clealy audible noise. But again, at or near max volume. I'm not saying it's common. It's not. But there are some classical songs and soundtrack music that pushes the c5 to it's limit. That's all. Plus with any player, if you use any eq, you need to cut the gain via eq app to prevent clipping. This makes it worse. But i would bet most people never even hear it. Just saying... I have music on cds that is quiet enough for me to max the c5 and have it no be loud. At this volume using the volume knob gets loud too.

If the c5 switches when no audio is detected then mine is broken ;-) my digitally silenced file plays continuous noise at or near max volume. If i understood you correctly...

 

In this experiment, you're effectively disabling zero crossing detection.

 

Zero crossing detection can only work when the amp sees an audio signal. The chip waits up to 50ms for the signal to cross the voltage axis (noise * 0 = 0). Playing pure silence means there's never a reasonable voltage transition, so zero crossing doesn't happen. And at max amp volume, you're multiplying the source noise floor by the amplifier's gain. That's not going to be silent with any amp, unless you have an amazingly quiet source. When playing "silence" at max volume, random source voltage fluctuations near V=0 remain unpredictable within the 50ms detection window (Noise * small voltage = noise). Thus, zero crossing has no opportunity within 50ms to make a silent transition. Try listening to music, or a sine wave while changing volumes. C5 will observe the music signal and volume transitions will be clean. Hope this all makes sense. There's a great pictorial explanation somewhere, which I can't seem to dig up...

 

This theory is only interesting if you listen to nearly silent recordings at near max volume. Such recordings are often close to their own noise floor, so avoiding noise is challenging regardless of the source/amp/headphones.

 

Alright, enough engineering talk for tonight ;)

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post #1244 of 3340
Quote:
Originally Posted by jseaber View Post

 

In this experiment, you're effectively disabling zero crossing detection.

 

Zero crossing detection can only work when the amp sees an audio signal. The chip waits up to 50ms for the signal to cross the voltage axis (noise * 0 = 0). Playing pure silence means there's never a reasonable voltage transition, so zero crossing doesn't happen. And at max amp volume, you're multiplying the source noise floor by the amplifier's gain. That's not going to be silent with any amp, unless you have an amazingly quiet source. When playing "silence" at max volume, random source voltage fluctuations near V=0 remain unpredictable within the 50ms detection window (Noise * small voltage = noise). Thus, zero crossing has no opportunity within 50ms to make a silent transition. Try listening to music, or a sine wave while changing volumes. C5 will observe the music signal and volume transitions will be clean. Hope this all makes sense. There's a great pictorial explanation somewhere, which I can't seem to dig up...

 

This theory is only interesting if you listen to nearly silent recordings at near max volume. Such recordings are often close to their own noise floor, so avoiding noise is challenging regardless of the source/amp/headphones.

 

Alright, enough engineering talk for tonight ;)

 

No that's good.  Thanks.  But I do hear the volume change noise with music and it gets louder as it gets louder.  That made sense trust me. :-P  So what happens when you have a song with a dead silent passage for two seconds?  Does the amp detect the silence and do something for that part of the song?  Let's say theoretically you had extremely quiet beeps of music with a second or two of dead silence between every beep.  Is the amp not rendering that continuously?  I guess I'm confused?

 

If you play this sample on the C5 from a portable device like an ipod you should be able to listen at max volume.  

 

https://dl.dropboxusercontent.com/u/48137075/Claire%20de%20Lune.wav

 

Keep in mind I'm using the er4s, so you need to have a somewhat demanding earphone.  It shouldn't be too loud.  But you'll notice a lot of noise.  That noise isn't "all" in the song.  I can listen to it on my apogee computer interface louder than that with half the noise.  I realize the song has noise to some degree, but it sounds noisier on the C5 at max and the volume ticks get louder as you turn it up.  I don't expect max volume to be dead silent, but that was the whole reason for my original comment.  For demanding headphones it would be nice for a little more power, that's all.  Not a nock at the c5.  I think it's amazing. :-)  And it more than powerful enough for most earphones/headphones.  So, it's probably a great balance considering it's portable and you want some battery life out of the thing. :-P

 

Also, listen to that sample and think that if you use an eq where you need to cut down the pregain a bit it's going to be even quieter than that. :-o

post #1245 of 3340
.....what the hay? Such music exists? You can't even analyse the waveform in Audacity is how quiet that track is.

MacBook Pro -> Audirvana Plus (maximum volume) -> ODAC RCA out -> O2 (1.0x gain, maximum volume) -> V-MODA Crossfade M-100 (sensitive headphone) or K 701 (insensitive headphone)

Plenty of noise with this setup.


Clip Zip (maximum volume) -> FiiO L2 -> C5 (low-gain, maximum volume) -> headphone

Sounds pretty much the same to me....


I repeated the above but with the O2's 2.5x gain and the C5's high-gain; I heard pretty much the same thing. A lot of pink noise kind of sound.



Amplifying the track in Audacity with a whopping 56.3 dB amplification, I get the following spectrogram:

That's...a lot of noise in the track.
Edited by miceblue - 8/8/13 at 10:35pm
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