Silver / Black with all tube option is with all tube: 2 x chinese 6z4 rectifier , 2 x 12au7, 2 x 12at7 , 1x decoration tube(no function)
Silver / Black without tube option, we send the preamp without preamp tube, except decoration tube and rectifier, so you need plug your 12au7 and12at7 tube after received the preamp to work with it
This version of 728A preamp is with tones adjustables:
Wonderful stereo Pre-Amplifier, built with the best parts available,(HIFI EXQUIS)
The pre-amplifier improved based on famous Wada Shigeho’s Style Electric circuit, which was Introduced by Wada Shigeho in the early 1960s and gave an excellent performance.
Regarding the Wada Shigeho’s Style Electric circuit, it not only still keep the good features of Marantz7,meanwhile it have superrior features in Dynamic, High/Low Frequency Response, Resolution and Signal to Noise Ratio as compared to Marantz7.But apart from above features, it’s also not inferior to Marantz7 in Sound stage and airy feeling. Adopt 4 PCS paper in oil capacitors and German WIMA capacitors for coupling effect, make the sound warm and delicate.(HIFI EXQUIS)
Product characteristics :
The reference of Wada Shigeho’s circuit to improve lines and adjust according to the different uses of the bile duct peripheral component parameters to maximize the strengths of the bile duct , so that the machine can no matter what the outstanding performance of the bile duct . Japanese and Shigeru launched in the early 1960s, the performance is excellent. It maintained a Marantz7 mellow and full of musical taste characteristics, but regardless dynamic , transient, high frequency response , power analysis , signal to noise ratio than Marantz7 good , and in the sound field , transparent flu and Marantz7 enough to keep pace .(HIFI EXQUIS)
- 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 : 12AT7×2, 12AU7×2, 6Z4×2, 1x decoration 9pin 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 or Silver front panel to choose
The export-oriented unit 728 in the third generation on the basis of preamp after many improvements made , compared with the original machine , elegant and dignified appearance , taste extraordinary.
In addition to retaining all of its advantages, it also increases the following advantages :
- 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.
Tube Amplifier Precautions
1. Tube amp must connected with speakers before turning ON. Strictly prohibit send signals to amp without connected loads(speakers) or load short circuit when the switch is ON. (Hifi exquis 1101017)
2. Too high or too low power supply voltage does irreversible harm to the amp,preferably less than 5% of the specified voltage. If your mains voltage exceeds this value, often best to use with the AC power supply.
3. Temperature is higher when tube amps working, placing attention to ventilation, cooling. (Hifi exquis 1101017)
4. In the boot or just shut down for a period of time (within 30 minutes) Do not spill liquid on the tubes.
5. You should take about 100h time to operate the amp.RUN-IN to the amp gives it’s best and stable sound.so during the first 100h use time the sound maybe is not the best,you can also use your own run-in method.
6. If you donot sure how to plug the tubes, please contact us before try it
All tube amplifier used with stereo mode: L(left) and R(right) speakers.
Normally there are 6 speaker cable connectors: +8L, +4L, -0L, -0R, +4R, +8R
Example: +8L and -0L are for connecting with your Left 6-8ohms speaker
-0R, +4R is for connecting with your Right 4ohms speaker
Tube amplifier guaranty :
Tube amplifier Guarantee: 6 months for tubes sold with amplifier, 1 year for the amplifier and PSVANE tube