Xiangsheng manufacture have 3  different 728A preamplifier model,

1. 728A without Ton adjustement

2. 728A with Ton adjustement without remote

3. 728A with Ton adjustement with remote with balanced input and output (we sell this model in this page)

This page we sell  the 3nd model :  728A with Ton adjustement with remote with balanced input and output

Silver / Black No Bluetooth: option is preamplifier come WITHOUT Bleutooth module:

Silver / Black with BT: option is remote control version with Bleutooth 5.1 module:

Wonderful stereo preamplifier, built with the best available parts (HIFI EXQUIS).

The preamplifier is improved based on the famous Wada Shigeho's style electric circuit, which was introduced by Wada Shigeho in the early 1960s and delivered excellent performance.

Regarding the Wada Shigeho's style electric circuit, it not only retains the good features of the Marantz 7 but also exhibits superior features in dynamics, high/low-frequency response, resolution, and signal-to-noise ratio compared to the Marantz 7. Apart from these features, it is also not inferior to the Marantz 7 in soundstage and airy feeling. It adopts 4 PCS paper-in-oil capacitors and German WIMA capacitors for coupling effects, resulting in warm and delicate sound (HIFI EXQUIS).

Product characteristics :
The reference to Wada Shigeho's circuit allows for improvements and adjustments tailored to different uses of the bile duct peripheral component parameters, maximizing the strengths of the bile duct. This ensures that the machine delivers outstanding performance regardless of the application. Introduced by Japanese and Shigeru in the early 1960s, the circuit exhibits excellent performance. It maintains the mellow and full musical taste characteristics of Marantz 7 but surpasses it in dynamic response, transient performance, high-frequency response, power analysis, and signal-to-noise ratio. Additionally, in the sound field, it achieves transparency and fluency, comparable to Marantz 7, ensuring it keeps pace (HIFI EXQUIS).

Parameters:

• Size : 430 × 90 × 290mm

• Input impedance : 100K;

• Output impedance : 600 ohms

• Output max volatage: 15v

• SNR : 90dB;(HIFI EXQUIS)

• Frequency Response : 10Hz - 30KHz;

• Distortion : ≤ 1%.

• Input Power :    AC100V-AC240V available 60Hz/50Hz

• Output Tube :    2× ECC82(Same to 12au7),2×ECC81(Same to 12AT7),6Z4×2,  1x decoration 9 pins tube

• Input Sensitivity :    400m

• Humidity :    35%—80%(HIFI EXQUIS)

• TMD :    less than 0.01%

• Input Jack :    4 groups

• Output Jack :    2 groups(same voltage),you can connect double same amplifiers

• Net weight : 8.5kg,

• Package size weight : 11.8kg

• Colors: Black orSilver front panel to choose

Features:
The export-oriented unit 728, in its third generation, has undergone numerous improvements based on the preamp. In comparison with the original machine, it now features an elegant and dignified appearance, exuding extraordinary taste.

In addition to retaining all of its original advantages, it has gained the following enhancements:

• All-aluminum alloy cabinet, 4 imported permalloy transformers as the balance port, using ALPS original imported motor volume potentiometer, American DALI resistors, Panasonic resistors, military Dahongpao resistors, antique oil-immersed capacitors, Germany WIMA, German ERO, Siemens Melaleuca polypropylene capacitors, Teflon internal signal lines and other fever materials.

• Bluetooth 5.1 (option): support APTX-HD and LDAC, with CS4398 decoder chip

• The circuit board designed interior layout is more reasonable , clean and beautiful .

• The front panel with silver plating 6mm thick aluminum wire drawing process panel , blue power indicator tube , and adds a unique large window display tubes , with warm red-orange background , higher grade quality .

• Advanced sandblasting paint process sheet steel enclosure , high light metal knobs, a large cellular machine feet.

• 4 stereo input signal switch , rotary switch control using conventional sealed relays senior converted signal , avoiding the switching noise , long life.

• using a relay signal output delay , to be enlarged after the tube into the steady state relay output signal , avoiding the unpleasant noise generated in the tube preheating process .

• The output signal provides two output sets, both you can connect two power amp together, you can also connect two integrated Amplifier do tone regulator uses.

• Input and output interfaces that are used in a gold-plated RCA seat

• Increase the grid filter purification circuit , you can filter the grid and DC components of clutter .

• Taiwan good quality potentiometer volume control.

• Antique oil capacitors and German WIMA red MKP polypropylene capacitive coupling.

• Using the best quality in the transformer power supply R-type bovine ( Square transformers and toroidal transformers leakage magnetic flux leakage is large, and therefore have a greater radiation frequency noise, and small R-type is very small ) , using high-pressure tube rectifier in parallel , two large reservoirs and high-quality inductors filtering.

• With treble, bass, treble and bass straight ( bass and treble adjustment automatically shield ) , volume, balance adjustment.

Back panel without BT version view: