AMR DP-777 Signature Edition Dac

Conclusion

What is the sonic summary of the 777 Signature Edition?
Bass is deeper and more powerful, there is more air in the treble, background is darker with an overall
improved resolution.

Sonically speaking, expect simply more, significantly more of what the original AM‐777, CD‐777 and DP‐777 all
delivered in spades – pure, natural music that flows through your music system.

The following is a detailed overview of each aspect of the 777 Signature Edition features as compared to the previous standard production model.

1. AMR Tri‐Core Silver capacitors

Each and every capacitor will have a small range of frequency in which it operates optimally. Different frequency range requires different capacitors for the best performance. With the all new AMR Tri‐Core Silver capacitors, each capacitor is operated in its best environment to produce the best sound. Along with the silver wiring, its coverage and transparency is as close to the “no capacitor” principle as it gets.

The high‐end normally practice is to parallel different capacitors – but all the capacitor share the same loads, AMR developed an unused topology which even spreads the load inside the tri‐core capacitor.

The upper frequency range is covered by a silver leaf capacitor. The mid‐range is covered by a film & foil electrolytic capacitor and the lower frequencies are covered by a polypropylene capacitor. Just as important, they all work within their most optimal frequency range by sharing the load intelligently. Finally, all of the elements are casted in a natural wood body in a special resin for nil microphonics and a natural, organic tonality that is unsurpassed.

2. General Electric 5670 NOS valves

The 6922 tube family is ubiquitous. It is a mainstay of nearly every tubed‐product out there and for very good reason; it has become one the most popular tubes. With AMR’s in‐depth tube knowledge, we have upped the ante and brought the GE5670 as a replacement for the venerable 6922.

The GE5670/2C51/WE396A/6N3 traces its roots back to its original design as the premium version of the 6922. Compared to its 6922 cousin, among other features, the 5670 has improved warm‐up, grid current, noise and microphonic tolerances. There is just no comparison.

With these features, it comes as no surprise that the GE5670 is sonically “heads and shoulders” above the 6922 family. Despite the same physical 9‐pin setup, the electrical configuration is different hence the 5670 family requires a specialist adapter which AMR developed from the ground‐up, commissioning a specialist mould to install the GE5670.

3. Quad‐Core Digital Engine

We have always been enamoured with the Multi‐bit chipsets as their technology reflects a “golden era” of digital design based upon sonic performance as opposed to profit. With a Quad‐Core configuration of four Philips UDA1305AT Multi‐bit chipsets, the sonics are now even deeper and richer with an inner resolution that is right up there with the very best of an “analogue sound” that is startlingly close to vinyl.

Along with an all‐new Digital Engine design (see later features), the new Digital Engine is right at the edge of digital audio design.

4. Additional clock buffers

AMR’s digital is already renowned for its digital technology, and the SE takes it even further ahead with jitter that is now at the vanishing point.

With state of the art digital design and implementation, the original DP‐777 already uses “Femto seconds” clocks that in its own special way, surpasses the very best industrial‐grade Femto clocks have to offer. Now with the SE version, we added a specially designed clock buffer for the Femto seconds clock, which further improves the performance of this state of the art design. This is the AMR difference, we start where others finish and push on, much further than what is thought possible.

5. Re‐optimised Clocking arrangement*

There is the XMOS USB platform and there is the AMR/iFi XMOS USB platform. Inside the XMOS, there is a radical “Star‐Clock” scheme in the AMR/iFi‐XMOS implementation. This is a major departure from the traditional “Daisy Chain” clocking scheme provided originally by XMOS which many others use.

6. Latest XMOS interface with proprietary customised firmware*

AMR is one of the very manufacturers to write its own software to run with the hardware. So in the case of the XMOS USB chipset, it was hand‐picked for its best performance but we brought it in‐house and our software development team analysed it down to the silicon‐die level and wrote a completely new program from there which optimises the latest 8‐Core XMOS chipset.

7. Completely re‐designed 4‐layer gold‐plated circuits boards)

All‐new 4‐layer PCB improves ground and PSU decoupling. For example, X7R‐1210 and C0G‐1206/0603 capacitors improve PSU decoupling about 10‐ 100 times over Sanyo OS‐CON (which are already audiophile‐grade!). The C0G capacitors are Teflon/Polystyrene grade of performance and are used widely in the DP‐777 SE and backed by the very best option X7R capacitors for large capacitance ‐ theX7R 1210 types have around 100 times lower parasitic resistance than OS‐CON and are effective to well past 1MHz (OS‐CON drop out at 300KHz).

The original 777 design used X7R in place of C0G and Y5U where we now use X7R in a special format. Along with the previously outlined improved clock system, along with the more widespread use of SMD components, current loop distances have been halved (with 50%+ improvement in most cases).

Several years back, at the time of the development of the DP‐777, one could only get X7R in small sizes and largish values, anything real big was electrolytic or Y5U.

By comparison OUR X7R cap’s from TDK Japan are about equal to Mylar Film Cap’s, but 10 times smaller = 10 times shorter current loop, if applied with real attention to detail. The exceptional parts count continues including ELNA Silmic Cap’s for example. What is the measured upshot of all this? Our decoupling system now is good to >> 100MHz, including 4‐layer PCB (using the PCB as capacitor) to > 1GHz. It just has to be measured to be believed.