Mr_G
Posts: 67
I love YaBB 1 Gold!
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FS Audio Gd C2.2 Headphone amp - $275
« on: January 30th, 2017, 3:29pm »
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I would like to sell my Audio Gd C2.2 headphone amp. It was purchase in Aug 2012 for US$365. I would like to sell it for S$275 or your best offer. It has excellent synergy (3W at 40 ohms) with all types of headphones, like HD 800S, Audeze LCD, etc. It has no technical or cosmetic issues. I personally used it with LCD 2 and HD800S. Contact me at gavin2005@gmail.com. I'll only respond to reasonable offers.
http://www.audio-gd.com/Pro/Headphoneamp/C-2new/C2.2EN_Tech.htm<
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Headphone amp specifications
S/N Ratio 118db (Input short)
Output Level 11V RMS
Output Power
40 ohm: 3000MW
100 ohm: 1200MW
300ohm : 400MW
600 ohm: 200MW
Gain
4DB (Gain setting L)
13DB (Gain setting H)
Volume Characteristic Applied I/V change volume control
Output Impedance
1.5 Ohms (HP amp)
Input Impedance
47K Ohms (RCA input)
<10 Ohms (ACSS input)
Frequency Breadth
2Hz to 130KHz (ACSS input ,1V output level)
Power Requirement
Version 200-260V AC 50/60 Hz
Power Consumption
18W
　
Dimensions
W240 X L320 X H80 (MM, Fully aluminium )
"Design Features:
The C-2.2 applied the ACSS is a non-feedback technology made with fully discrete amplifiers. Most people know the global feedback design can offer better specs in test measurements, and non-feedback can't do well in test measurements but can offer better sound for the human's ears. Here is a conflict of the classic circuits. But the ACSS opens a new field, it can offer a least coloration sound which is more neutral with very low distortion and high linearity. So it can retain the dynamics, detail and neutral sound but not sound bright or harsh. The output buffers are Non-feedback. For low impedance, we applied a diamond output stage (the MOSFET and transistor combined the Cascode stage )which is quite less colored than most conventional circuits.
ACSS non-feedback amp, ALPS 27 volume pot, Neutrik socket
C-2.2 applies the excellent analog output stages, but these are not the only keys of the best sound. The power supply is most important. Even applying the best amp designed , if matched to a normal power supply, the total sound may still be average or sound musical but can't be neutral and detailed.
C-2.2 applied the class A parallel connection PSU for the ACSS analog output stages.
The class A parallel connection PSU has very high input impedance for avoid pulse through the PSU from affecting the amp and low output impedance with very fast speed and high linear , so it is a very clean power supply. In my experience, its sound is better than battery power supply, better human sound and neutral.
Class A power supply.
C-2.2 has three pairs of inputs: one set of ACSS current mode input, and two single-ended RCAs inputs. If the input signals are coming from RCAs, they are internally converted into current signals and then amplified. To use the C-2.2 as a preamplifier, there is one set of RCA output for your power amp connection.
In order to minimize interference and distortion of sound quality, the left and right channel circuitries are completely separated.
C-2.2 uses an all aluminum alloy chassis to prevent the eddy current of the transformer from interfering with the circuit board.
About volume in ACSS circuits:
The volume control is also different from conventional technology. Conventional volume control technology is the volume control implement in the analog amp input stage through a volume pot to reduce the signal . The volume pots quality effect the sound quality direct , the low quality volume pot cause lost the detail and channels imbalance cause the soundstage distortion . Even the high performance volume pot still cause the detail lose. Whatever quality volume pots, must cause the S/N worst .
But in the C-2.2 , we applied the I/V conversion volume control , the volume control just a variable passive I/V conversion place at the ACSS amp output , where the output is the current signal, not the voltage signal. The volume control is I/V conversion, and the volume depends on the current (I) conversion to the voltage (V). (Like R-2R D/A chips output passive I/V conversion) It can keep the signal frequency band flat and not lost any detail. It can't degrade on sound quality in every volume level . After the volume , there are four groups diamond non-feedback buffer output stages offer the very low output impedance
Mark Levinson also knows that current volume control has great benefits, so in their Top End preamp NO.32 volume control, they use many components to change the signal to current signal (I), then implement the volume control , and then change back to voltage signal (V) again. But C-2.2 is simply a more complete work in terms of the current signal, and technically, it is superior to conventional technology. The less conversion bring much neutral sound ."
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