Audibly Perfect Channel Balance
Digital stepped attenuation with zero-crossing detection and 1dB attenuation steps provide smooth volume adjustment at all volume levels, even with sensitive IEMs.
DC Coupled Signal Path
C5 uses a purely resistive signal path. Thin film, 0.1% tolerance resistors ensure low noise and high channel accuracy.
Dual LDO Power Regulation
High performance audio starts with clean power. Supply rails are filtered by impressive TPS7A4700 and TPS7A3301 regulators to achieve ultra low supply noise at a constant output voltage of+/-7V.
Smart USB Charging
Powered by a large 1200mAh Li-Ion battery, C5 quickly charges from any USB port (computer, tablet charger, cell phone charger, etc.). A single LED indicates battery status: solid green while on, blinking while battery is low, or blue while charging.
- Digital Stepped Attenuation (63 steps + mute)
- Dual Gain: 2.3x or 6.5x, MOSFET controlled
- Bass Boost: +6.5dB @ 80 Hz
- 20 Minute Low Battery Indication
- 0.1% Thin Film Resistors
- 1200mAh, 3.7V Li-Ion Battery
- Ultra Low Noise +/-7V rails, NO power degredation
- 3.5mm Input and Output Jacks
- Gold Immersion, 4-Layer Printed Circuit Board
- Atmega168A MCU w/Opensource Arduino Firmware
|Frequency Response||+/- 0.02 dB|
|THD+N (20-20kHz, 150 Ω)||0.0009%|
|Crosstalk @ 150 Ω||-67 dB|
|Inter-channel Phase @ 1kHz||+/- 0.01°|
|Channel Balance||+/- 0.55 dB, all volume positions|
|Max Output @ 150Ω||3.337 VRMS|
|Max Output @ 600Ω||4.146 VRMS|
|Power Supply||14.0 Vpp|
|Output Impedance||2 Ω|
|Battery Run Time||14 Hours|
|Charge Time||2 Hrs to 80%, < 5 Hrs to 100%|
|Operating Temp||–40°C to 85°C|
|Operating Humidity||0 to 85% Rel. Humidity|
|Dimensions (excluding switches)||99.5 x 49.0 x 14.0 mm (LxWxH)|
JDS Labs C5 Review:
I would like to thank John for sending me this engineering sample of the C5 for me to review. I will write as honest review as possible, all opinions expressed are my own, this is a subjective review from many hours of listening.
IPod Classic 160gb (rockboxed) – Silver LOD – C5 - Alclair Reference CIEM, Sunrise Audio Dragon2 earbuds
Packaging, accessories and build quality:
Packaging I cannot comment as I did not get proper retail packaging, but from others that received their amps after me it comes with a black box saying JDS Labs on it. Inside you will find the C5 sealed in an anti-static bag and a standard USB cable to charge it. Inside the anti-static bag you will also find 4 adhesive rubber feet for the amp, so it doesn’t slide when on a desk, or doesn’t scratch the back of your DAP when strapped together. I think to fully complete the package, they could include a short mini to mini cable, and maybe 2 amp straps would be a great extra.
Build quality is a strong point of JDS, the casing is machined aluminium, with a matte anodised finish, very smooth to the touch, the end plates are brushed aluminium with all ports very precisely cut and everything fits flush. They include laser engraving on their amps, and you can opt for custom artwork for no extra fee when ordering, a great customisation. Headphone jacks are tight and the on/off switch I very high quality. The bass boost toggle is plastic and doesn’t stick out much, which means that with everything plugged in it is not going to be accidently turned on or off. The volume control is digital, and flicks to both sides and coming back to central, like the old creative mp3 players used to have. You push the volume rocker in to change the gain from 2.3x to 6.5x, also the gain is not something that will be accidently pushed in when in your pocket so no worries about blowing your ears by accidently upping the gain.
Volume rocker, bass boost and battery:
As I mentioned earlier, the volume rocker is digital, and is controlled by Arduino code so it can be reprogrammed. The advantages of digital volume controls is no channel imbalance even at the lowest possible setting, and when implemented well work very well. I would say JDS have got it perfect, if you hold the volume rocker to volume up, it increases to full in a few seconds. But then each individual step is quite small so you can easily fine tune your listening volume (63 steps in total). It works really well for sensitive in-ears as you don’t suffer channel imbalance, but still has enough power for most full size cans.
The volume level is remembered every time you switch the amp off, so when you switch it back on it will be at the same volume from when you turned it off, which is also good and safe, no volume wheel accidently going up when turned off, and also means you don’t have to constantly search for your desired listening lever.
Bass boost is implemented at a 6db increase at 80 Hz, which is perfect for some and not so perfect for others, a common suggestion is to make a 3 way switch, say 3db and 6db increases. I think the bass boost if perfect for cans that slightly lack in the lows, or just normal cans for when you’re out and about for that extra fun. The great thing about the bass boost is that when on it doesn’t interfere a lot with the other frequencies, and it has this kind of theatre bass effect, not a big slam and lots of rumble, just quite a bit of added body and sounds like you’ve turned on a subwoofer in a home theatre setup. I really like this bass boost, and with earbuds or can slightly on the leaner side of things, it really adds to the sound.
Battery life is supposed to be around 14hrs, I have not tested this yet, but other users have had 11-13 hours real time use. The battery only takes around 2-3hrs to fully charge, and the amp can be used whilst being charged, and also the charging circuit cuts off supply to the battery once fully charged. So it will not damage the battery and it also means when fully charged you can run it off USB power purely without worrying about the battery.
Ok so where to start, this is a pretty neutral amp, it was made to perform very well in objective tests and also to be transparent like a portable O2. Well they have done a great job, the sound is mainly on the transparent side like the O2 but I do sense that the C5 has slightly forward mids, the lows and highs are where they should be and everything sounds just right. The sound is very controlled, with quick recovery and attack, the lows are tight deep and impactful, and the highs airy and detailed. The C5 has a sort of intimate presentation but also spacious sound, the soundstage isn’t huge, a little larger than average but instruments are accurately placed in the soundstage. Overall the C5 is a fairly neutral and clean amp, with only slightly, and I mean very little, forward mids.
To give you a better understanding I will compare it to the JDS Labs O2 and C421 (AD8620).
Vs C421 (AD8620)
Well we have two quite different amps here, the C5 uses the OPA2227 and the C421 AD8620 op-amp. The C421 has more sibilance in the upper mids, and also details and nuances are more easily heard with the highs being more present and also slightly brighter. But the bass is not as tight and controlled as the C5, and also it sounds a little more congested even though it has a slightly wider soundstage. I think the C421 has a fuller sound, but more aggressive presentation, the C5 sounds a little inoffensive and laid back when compared to the C421, but the C5 sounds better overall as it is more controlled, natural and flat. The C421 is still a great amp and is very fun to listen to, but I prefer the accuracy of the C5, even if the presentation is a little more laid back.
Well the C5 was designed to be like the O2 only in a portable package, I must say when compared side to side they sound very close, but differences are still noticeable. The O2 is better overall, the soundstage is wider with a more spacious presentation, the C5 has quite an intimate presentation but airy sound at the same time.
Overall the C5 is a winner, with the digital volume being perfectly implemented and a great sound that is nearly as good as the O2. I have the O2 for home and C5 for portable, and am happy with both.
JDS Labs have excellent customer service, and the prices are very reasonable for the product, this amp can compete with amps below $300 easily. I look forward to future JDS Labs products.
Tracks used to compare amps:
Diana Krall - the Girl In The Other Room (FLAC)
Silverstein - Discovering the Waterfront (320kbps mp3)
Edited by ostewart - 11/8/13 at 3:19pm