Detail of the Current Conveyor (ACSS) Technology
There are a lot different DACs in worth, they had different design and output impedance . For avoid the sound quality effect by different DAC's output impedance, in the NFB-1AMP, it had design two pair single-ended class A FET buffers in the input . All the input signals through these FET buffers, the output impedance had become very low, even the source had high or low output impedance.
The FET buffers working on pure class A state, and it is so short signal journey , it can keep the sound quality without coloration ,dry and harsh .
NFB-1AMP had the same ACSS design with our top grade model Master 9 . It is a pure class A design built by discrete analog stages without any OPA or coupling caps in the signal channels.
They seem complex , but in fact they are the most simple design the world has ever had , their a lot components to process the power supply. The simplest and shortest signal journey brings out the most neutral and least colored sound.
The ACSS is a non-feedback technology made with 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.
All signal gain is in current area, all transistors work in class A mode.
The NFB-1AMP has all components exactly matched before installation.
Super low THD （Test by AP SYS-2722,0DBV output level) Flat frequency response （Test by AP SYS-2722)
Strong class A output stages:
The NFB-1AMP had design a pare diamond difference output stages, every parts had exact matching before assemble so don't need any human adjustment .
The output stages had four pair 15W transistors ,they also working under class A state . Drive most headphones can working under pure class A state.
The class A parallel connection PSU has very high input impedance to avoid pulse through the PSU from affecting the preamp and low output impedance with very fast speed and high linear, so it is a very clean power supply.
The NFB-1AMP applies seperate linear PSUs for the display and control parts, avoid the disturbances through power line from affecting the amplifier.
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 NFB-1AMP , 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 NFB-1AMP 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 .
In NFB-1AMP is applied a digital control relays based volume control. .NFB-1AMP has total four channels through changing the DALE resistors to control the volume for avoid channels imbalanced ,achieve the best performance and sound quality of the gear.
NFB-1AMP have 100 steps volume control, very smooth control for both high / low sensitivity headphone and speakers. While users change the volume, the combine relays break or close, it may had slightly switch sound on output and disappear while stop change the volume.
NFB-1AMP Supper two sets Exponential volume characteristic
Static storage mode control software:
In most control softwares design, the MCU will continuously output data to the perform parts , the MCU had the very high speed, so the output data become high frequency impulses disturb the audio signal circuits make the sound worst . This product had applied static storage mode control software , the MCU output once control data and save in the perform parts while just power on and users operate ,then stop output data until users next operation. This design make the sound quality improve on the clear and transparency .
The NFB-1AMP design had not compromise , it's built by full aluminum chassis, the transformer interference can't through the aluminum chassis transfer to the analog amps, and there are two shield boards for insulate the transformer and the power supplies.
Uses all Hi-end grade components, including DALE resistors, WIMA caps, custom order NOVER (UK brand) caps.
The equipment has a 10 year repair warranty by Audio-gd the manufacturer and a 10 year product support by the Locally Appointed Agent
Audio-gd the manufacturer burn in all equipment for a period of more than 100 hours, the equipment is quality control checked and tested several times before dispatch.
The 10 year repair warranty by Audio-gd the manufacturer and the 10 year product support by the Locally Appointed Agent does not cover user abuse, improper use of the equipment, electrical surges, electrical transients, lightening damage, use of computer ports USB3.0 or higher and damage to receivers due to unshielded and non-standard USB cabling.
The equipment supplied to the Locally Appointed Agent from Audio-gd the manufacturer is for use within the boarders of the Republic of South Africa and must be mains earthed via the power cable supplied by Audio-gd the manufacturer and fitted the a South African 3 pin mains plug.
First year repair warranty:
Should the equipment have any manufacturing defects which is not caused by the user, the customer is to ship back the equipment to Audio-gd the manufacturer or the Locally Appointed Agent for assessment and inspection. The customer must submit the shipping bill following which we will reimburse the amount to customer.
Note: Audio-gd the manufacturer or the Locally Appointed Agent will only refund shipping cost equal to what the customer initially paid for shipping when placing the order. Audio-gd the manufacturer or the Locally Appointed Agent will repair the defective product at no charge and return ship the equipment to the customer.
1, Should the equipment be found to not to be faulty on assessment and inspection by Audio-gd the manufacturer or by the Local Appointed Agent but the customer has return shipped the equipment, Audio-gd the manufacturer or the Locally Appointed Agent will not cover the shipping cost, The return shipping will be for the customers account.
2, Should the customer notify Audio-gd the manufacturer or the Locally Appointed Agent within 7 days of receiving the equipment and report the equipment faulty. Audio-gd the manufacturer will cover the return shipping cost of the equipment to China and will return ship a new replacement unit to the customer.
3, Should the customer notify Audio-gd the manufacturer or the Locally Appointed Agent within 7 days of receiving the equipment, and the equipment found not to be faulty by assessment and inspection by Audio-gd the manufacturer or by the Locally Appointed Agent the unit will be return shipped to the customer, the return shipping costs are for the customers account which must be paid in full prior to dispatch.
4, The equipment must be return shipped by the customer complete with the original box and foams including the original cabling, attachments (jumpers), and proof of purchase, should damage occur during shipping we do not cover the repair charges.
5, Audio-gd the manufacturer or the Locally appointed Agent will assess, inspect and test the equipment based on a world standard, we will report the status of the assessment and inspection to customer.
After the completion of first year repair guarantee :
Should the equipment have any faults or manufacturing defects which is not caused by the user, the shipping will be for the customers account (to and from Audio-gd the manufacturer or via the Locally Appointed Agent), while Audio-gd the manufacturer or the Locally Appointed Agent will repair the product at no additional labour cost.
User inflicted problem repair guarantee:
Should the assessment and inspection reveal that the equipment has been damaged by the user, the customer will be quoted for the repair costs and will be charged for the return shipping costs by Audio-gd the manufacturer via the Locally Appointed Agent.
Sale of Audio-gd equipment (second-hand):
The warranty does not cover equipment that have been purchased on the second hand market. The warranty is not transferable.