[jseaber]

Quote:

Thanks John that's good to know.So do I still need to connect the temperature monitoring pin(white wire) to the S3 battery "T" pinout with a 10k thermistor/resistor or just to the C5  battery temperature input alone will do? Anyway I will try this once I get hold of a 10k thermistor/resistor to see if it would work.(need to get one frist).

 
You'd connect a 10k thermistor/reistor between pin1 of the C5's battery header and ground. Here's the pinout:
 
 

 

[archro]

Hello Jseaber, the C5 is a really good  AMP, but I am still have a question about how the C5 power management works?
since the one cell Li Battery is the only power resource so you have to boost it from 4.2v to 14V （+/-7V)  could you mind do some introduce about this part or and what kind of IC can been use in a really small  PCB area.
and when the battery voltage drop,  does the positive and negative voltage still in balance or even the positive/negative always keep in +/-7V?
 
very appreciate if you can share some knowledge to me.

 

[jseaber]

Quote:

Hello Jseaber, the C5 is a really good  AMP, but I am still have a question about how the C5 power management works?
since the one cell Li Battery is the only power resource so you have to boost it from 4.2v to 14V （+/-7V)  could you mind do some introduce about this part or and what kind of IC can been use in a really small  PCB area.
and when the battery voltage drop,  does the positive and negative voltage still in balance or even the positive/negative always keep in +/-7V?
 
very appreciate if you can share some knowledge to me.

Great question. The power stage is more than a single chip. Supply voltage to the opamps is always +/-7V. As the battery drains, the circuits compensate to maintain desired voltage. This means current consumption at the battery increases as the battery gets low, and you always hear maximum performance. Here's a C5 flow diagram that lived on our whiteboard for months:
 
 

 
 
We increased all 7V lines to 8V, and all 6V lines to 7V. The concept remains the same:
 
Li-Ion Battery --> Charging and Load Management IC (BQ24075) --> Positive and Inversion Boost IC (LT3471) --> Ultralow-noise LDO's --> Dual supply output
 
As you can judge from this flow diagram, the majority of C5's schematic consists of power circuitry. I've shared this with a few engineers. The first response was, "That's complicated." Another wanted to see FFT's, fearing the 1.2MHz boost/inversion stage would emit EMI/RF and make its way into the opamp output. He was pleased to see the result. Careful layout on the 4-layer PCB gives nice, clean FFT's (no harmonics!):
 
 

Output of C5 - 1kHz test signal (time-domain)
 
 

Output of C5 - 1kHz test signal (frequency-domain at 1.25kHz intervals)
 
 
 

Output of C5 - 1kHz test signal (frequency-domain at 50kHz intervals)

 

[JakeJack_2008]

Quote:

Since the C5 is still a fairly new product, you're probably not going to find someone who has heard that specific pairing, yet.
 
My headphone impressions with the C5 are limited to the K 701, V-MODA M-100, and Shure SRH940, but my observations between the C5 and Objective 2 have all been pretty consistent with my previous statements:

1. O2 gives the sense of a larger soundstage with more air between instruments; C5 sounds more boxed-in
2. O2 sounds a bit more dynamic; C5 sounds a little duller (not boring dull, but instruments don't sound as "full")
3. O2 has a smoother treble (I don't think smoother is the right word for this, nor is rolled-off, but it's not as fatiguing compared to the C5); C5 sounds a tad bit brighter
4. C5 has a midrange that is is a tad bit more forward and engaging; O2 sounds more laid-back

^ those last two points are probably what the Headfonia review was talking about, maybe.

Very good summary/review. This is reassuring.

One cannot go wrong with the O2. Thanx.
 
I am extremely happy with the O2 and ODAC from JDS Labs.

 

[archro]

Hi Jseaber, thank you for your kindly and patient replay, impressive design!
I am very clear about how C5 power system works.

 

[chemist323]

[size=medium]Thanks for all the great info.  I have a few questions after scanning most of the thread.  It seems that the only real PORTABLE competitor to the C5 is either the old c421 (discontinued) or from ClieOS’ shootout, the Leckerton Audio UHA-4.[/size]

• [size=medium]Has anyone compared the C5 and the UHA-4 or have an idea how it’d perform vs the C5?[/size]
• [size=medium]Will the C5 will pair up well with my cans: Denon AH-D2000 and DT990 32 ohm ?  [/size]

[size=medium]I’m definitely excited to get my first amp although it has been a long wait.  Thanks for your help![/size]

 

[Gintaras]

i would say was there anyone to compare C5 to UHA6SmkII? UHA4 is just older amp and 6S might have more appeal. UHA6 has a DAC section too so its higher cost is justified.

 

[miceblue]

Quote:

i would say was there anyone to compare C5 to UHA6SmkII? UHA4 is just older amp and 6S might have more appeal. UHA6 has a DAC section too so its higher cost is justified.

The UHA4 is probably what one would consider more portable, not to mention having the digital potentiometer like the C5. I would be interested in a Leckerton comparison too.
 
I just ordered a FiiO E12, so I'll write some comparisons between it and the C5 in a few weeks.

 

[HiFan]

Quote:

The UHA4 is probably what one would consider more portable, not to mention having the digital potentiometer like the C5. I would be interested in a Leckerton comparison too.
 
I just ordered a FiiO E12, so I'll write some comparisons between it and the C5 in a few weeks.

 

 
I do have UHA-4 and C5 in my hand. I can update a quick comparison in 2 days. I am not into UHA-4 that much since its sound stage is narrow and has a really weak power output. 
 
C5 is as portable as UHA-4 and comes with a nicer enclosure. As for FiiO, I am not that sure about their products. I had e11 and e10. Not very impressive. Maybe worth the price, but not even close to C5. Their cables are good though.

 

[chemist323]

Quote:

 

 
I do have UHA-4 and C5 in my hand. I can update a quick comparison in 2 days. I am not into UHA-4 that much since its sound stage is narrow and has a really weak power output. 
 
C5 is as portable as UHA-4 and comes with a nicer enclosure. As for FiiO, I am not that sure about their products. I had e11 and e10. Not very impressive. Maybe worth the price, but not even close to C5. Their cables are good though.

That would be awesome!  Thanks.  Also, C5 should pair up with my headphones (AH-d2000, DT990/32), right? 

 

[ThurstonX]

Just got the tracking # for my RED C5 

  This is my first headphone amp, but based on everything I've read herein, I have great expectations. I'll be using it with a 160 GB Rockboxed iPod Classic (all FLAC, all the time 

 ) and a Toshiba Qosmio laptop (probably at 24/96, though it'll do 24/192), with, mainly K550s, and occasionally Phiaton PS210s (iPod only). I expect the Bass Boost may come in handy with both.
 
I do have a couple questions that I'm sure y'all can answer.
 

• Is there any point/value in using the C5 with a car stereo? Normally I just go from the iPod's phone jack to an AUX in I hooked up for the Pioneer. Now I'll be using the LOD I got along with the C5, but I'm not sure the C5 is really needed. That would be double amping, yes? Anyway, curious to hear what you have to say.
• What about a DAC, like the ODAC? I've done a bit of research, and I gather it could improve the sound out of the laptop. Can the ODAC be used in a portable setup with the iPod? Aside from power issues, my guess is NO, as the iPod is Rockboxed.

 
Just wanted to say thanks to everyone who asked pertinent questions and posted reviews and advice.

 

[miceblue]

Just got the tracking # for my [COLOR=FF3300]RED[/COLOR] C5 

  This is my first headphone amp, but based on everything I've read herein, I have great expectations. I'll be using it with a 160 GB Rockboxed iPod Classic (all FLAC, all the time 

 ) and a Toshiba Qosmio laptop (probably at 24/96, though it'll do 24/192), with, mainly K550s, and occasionally Phiaton PS210s (iPod only). I expect the Bass Boost may come in handy with both.


I do have a couple questions that I'm sure y'all can answer.

1. Is there any point/value in using the C5 with a car stereo? Normally I just go from the iPod's phone jack to an AUX in I hooked up for the Pioneer. Now I'll be using the LOD I got along with the C5, but I'm not sure the C5 is really needed. That would be double amping, yes? Anyway, curious to hear what you have to say.
   
2. What about a DAC, like the ODAC? I've done a bit of research, and I gather it could improve the sound out of the laptop. Can the ODAC be used in a portable setup with the iPod? Aside from power issues, my guess is NO, as the iPod is Rockboxed.
   

Just wanted to say thanks to everyone who asked pertinent questions and posted reviews and advice.

1. I would say an external amp for a car stereo system isn't necessary based on my experience with the O2 and C5. With my setup (iPhone, FiiO L3, C5, cassette tape adaptor, car stereo system), the C5's bass was really distorted at high volume levels out of the C5, and was even worse with the bass boost on.

2. The ODAC can't be used with an iDevice period since you can't connect the two. Apple-certified DACs cost a fortune (in my opinion) too. For a laptop though? Sure thing, depending on how good your laptop's soundcard is of course. It makes a pretty noticeable difference in the soundstage and instrument separation/clarity from my laptops.

 

[cujobob]

hifimeDIY has a USB hub for iPad that may work for an iPod so that you can connect a DAC.

 

[jseaber]

Quote:

1. I would say an external amp for a car stereo system isn't necessary based on my experience with the O2 and C5. With my setup (iPhone, FiiO L3, C5, cassette tape adaptor, car stereo system), the C5's bass was really distorted at high volume levels out of the C5, and was even worse with the bass boost on.

 
Adding an amp has only helped in every case I've seen. Many car auxiliary inputs expect 1V, 2V or even 4VRMS line input, and have a high impedance input. So, pre-amplification is generally helpful in reaching the maximum signal input.

 

[ThurstonX]

Quote:

 
Adding an amp has only helped in every case I've seen. Many car auxiliary inputs expect 1V, 2V or even 4VRMS line input, and have a high impedance input. So, pre-amplification is generally helpful in reaching the maximum signal input.

Thanks, John and miceblue.  I suppose it can't hurt to test it out.  May have to schedule a little drive time Thursday afternoon/evening.  Spring is in the air... may as well add a little music to the mix