... a real sense of tubes

Project Zephyr ONE - 2a3 headamp

Posted in: Products / Custom device

Technical details:

Operation on low impedance (<100 ohm):    OTL (single end class A)
Operation on high impedance (>100 ohm):    Cathode SE autotransformer

Operation for planar headphones:    SE Output transformer (32 ohm)
Operation for ESC (STAX):   SE Output transformer (200 Vrms), PRO bias (580V)

Driver tube (& equivalent):    ECC88,PCC88, 6DJ8, E88CC, 6922...
Power tube (& equivalent):   2a3 , 45 ( two selectable mode )

Rectifier tube (& equivalent):    274B, 5U4G..
Regulator tube (& equivalent):   0D3, VR150, SG4S..

THD on declared power (3W 8 ohm 1Khz) :    0.950%
Input impedance:    47K
Freq. Response (+-3dB):    22-40kHz (SE trafo), 14-705kHz OTL
Sensitivity for declared power:    0,775Veff /0dB
Max. input voltage:     1,25Veff
Input conn:    2 x RCA , 1 x XLR
Out conn:    6,3mm jack, STAX pro, speakers 4mm
Supply voltage:    110-120/220-240V
Power consumption:    125VA
Dimension mm(W x D x H):    230x480x230
Weight kg:   15kg


In early March a gentleman from Italy contacted us (let's call him Marco) with request for  tube headamps (three identical copies) that could drive dynamic headphones (low and high impedance), planar magnetics or ortodynamic headphones, ESL (STAX) headphones and listen this headamp as a standard triode amplifier (SET) on normal, but a highly effiency speakers.

Interesting  challenge, demanding in terms of low noise and hum and with less compromises.
Also , have we succeeded in the project? For details about the project, construction and review of this device look here :


Picture 342a
Picture 273a
Picture 263a
Picture 222a
Picture 226a
Picture 331a

Related topics: