YSA100S-MK2 Reference  95W + 95W Stereo Valve Tube Power Amplifier

Audio Experience YSA100S-MK2 Reference is a 95W + 95W Stereo Valve Tube Power Amplifier.
It is a Class AB1 PP design power amplifier. It provides sound deep and wide stage, accompanies with reality sound image and a emotions sound presentation.

It uses one matched pair of Tung-Sol KT150 ( or Tung-Sol KT170) power tubes and Class AB1 UL PP working status to provide 95W adequate output for most of the Hi-End Speakers to ideal performance. Moreover, the high quality output transformer combines with high performance Class AB UL PP circuit design lead to an extremely low loss, wide sequence sound effect and excellent phases output. This power amplifier case structure and parts arrangement are perfect, the signal path is directly and shortly connected. Great heat dissipation, an anti-shock and anti-RF function to guarantee it works at a very stable status. For sure, this machine is produced by point-to-point methodology. 


The input stage is 12AU7  direct coupling to 5687WB driver stage to 6H30 cathode follow driver stage , The driver stage uses Miflex KFPM copper foil polypropylene film coupling cap to KT150 (or KT170 ) power tube , The KT150 ( or KT170 ) work at Class AB1 UL P-P mode to driver Hashimoto output transformer , The Hashimoto HW-100-5 CUT CORE orient high B output transformer has very low Insertion Loss 0.15dB only.  ( Many tube power amplifier in Hi-End audio market , Their have the output transformers is over 1dB Insertion Loss . only about 10% very high price tube amplifier use under 1dB Insertion Loss of output transformer ) . The output transformer has low insertion loss is very important , the best of the best is 0 dB Insertion Loss , The output transformers for High End tube amplifier need under 1dB  Insertion Loss . The Insertion Loss over 1.5dB output transformer will lost many low level music.

The power supply with two separately HVB+ power supply for power output stage and  input driver stage.



  ysa100smk2t.jpg (234086 個位元組)  The power supply with two separately HVB+ power supply for power output stage and  input driver stage 

  powerchoke.jpg (377989 個位元組)  lundahlinput.jpg (411015 個位元組)  Hashimoto output transformer , Lundahl (made in Sweden) input transformer.


 ysa100smk2i2.jpg (522023 個位元組)  Miflex KFPM copper foil polypropylene film coupling caps

hw1005.jpg (364115 個位元組)  hw1005b.jpg (258700 個位元組) The info of Hashimoto HW-100-5 CUT CORE orient high B output transformer.

Review by HiFi review    2018-10


Review by HiFi review #401    2019-10

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YSA100S-MK2 use KT170

kt170a.jpg (673536 個位元組) kt170b.jpg (579210 個位元組) 



Power On/Of, Input RCA/XLR Selector 

Output and T.H.D :  
1W per channel , 1kHz total harmonic distortion typically 0.15% (0.2% at 20Hz , 0.23% at 20KHz)
95W per channel , 1kHz total harmonic distortion typically 1.2% (2.5% at 30Hz , 2.5% at 20kHz)

Input :  RCA and XLR (balanced)

Input Impedance :  100K ohm is  RCA , 10K ohm is XLR .

Frequency Response:  

1W    20Hz ~ 100KHz ( 20Hz 0dB, 100KHZ 0dB)
95W  20Hz ~ 100kHz (20Hz -0dB , 100kHz -2.5dB)

Input Sensitivity :  1.3V / 95W       26dB Gain ( Test at 8 ohm )

Output Taps: 16 ohm ,8 ohms, 4 ohms.                                                      

Noise: Less than 0.5mV
Damping factor : approximately over 23

Phase Mode : Normal

Tubes Required for each CH:
(2) one matched pair KT150 Power Output , ( 1 ) 6H30 Driver, ( 1 ) 5687WB Driver , ( 1 )12AU7 Input .

Dimension: 433mm x 460mm x 233mm (W x D x H)

Total Weight: 29kg

Power Source: 220-240V,50/60Hz

Actual Price: 

Both input with XLR input and RCA input HK$32,300

Only RCA input without XLR input  HK$29,800.

The power tubes from KT150 upgrade to use KT170  add extra cost $1,300.


Room1308, 13/F,BLK C,.  
Kai Tak FTY BLDG.   
99-101 King Fuk ST,.   
San Po Kong,   KLN,.
Hong Kong
E-mail : info@ys-audio.com 
WhatsApp: 93440168   
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