AudioNemesis

zero-feedback, Class A mono HYBRID power amplifier

Echidnas (sometimes also Ekidna) are unusual animals living in Australia and New Zealand: they are small egg-laying (primitive) mammals that are covered with coarse hair and spines. So, it’s a very “strange” animal, it’s a “hybrid”. And it’s very “nice” and “sweet”.
We at called ECHIDNA our original topology for a hybrid power amplifier, developed and used for the first time in this model .
Echidna puts together, in an original form, a few known circuits and ideas, creating a very unique simple topology.
Echidna idea is simple: a triode voltage gain stage plus a bipolar current gain stage, without loop feedback.

ECHIDNA - Exclusive Circuit for Hybrid Improved Design by Nemesis Audio

is a very special amplifier with only 3 active devices in series to the signal.


All other devices are passive. So there are only 7 components (passive and active) in series to the signal!

The output stage is made by bipolar transistors only. It’s a complementary configuration composed by the output devices and the driver devices. As output devices we chose the best available audio power transistors: they are made by Sanken and they are ring emitter type. These devices are able to supply 17A DC, and up to 35A peak for 10ms. This out performs any requirement in real applications.

As driver devices we chose a very linear device, with 100Mhz Ft and a very low capacitance (ensuring low distortion in real life loads), made by Toshiba.

This output stage has no output choke and no Zobel network! Despite this, it is unconditionally stable and the low output impedance is assuring a high damping of the loudspeaker, for better bass response.
A DC servo circuit assures an output DC voltage near zero without output capacitors.

The amplifier has no protection system! So it’s not protected against short circuits. Warning!
This is the Echidna topology. A step beyond the other hybrid topologies. And, above all, a step closer to the MUSIC!

A few features:

• Mono amplifiers
• Class A up to 15Watt @ 8ohms
• Hybrid design with Echidna Topology
• Zero feedback (and feedforward) loop
• 3 actice devices in series to the signal (7 total)
• Pure triode input/driver stage
• Bipolar output stage, with Sanken ring emitter devices
• High current capability
• Low distortion and great neutrality
• Reactive load driver capability
• Very high stability
• No output choke — no Zobel network
• High damping factor
• Very short signal path
• High quality active and passive parts
• Fast and soft-recovery diodes
• Servo controlled output stage for 0 VDC offset
• No protection system
• Family chassis used for all other products

Specifications

• Frequency Response 20 Hz to 50 KHz + 0dB/ -1dB @ 15W @ 8 ohms
• 20 Hz to 50 KHz + 0dB/ -1dB @ 1W @ 8 ohms
• Gain 15 dB
• Power Output 15 Watts @ 8 ohms
• 27 Watts @ 4 ohms
• 45 Watts @ 2 ohms
• THD @ 1kHz <0.03% @ 1,5 W
• <0.3% @ 15W
• THD @ 20kHz <1% @ 15 W
• Input Impedance 475 kohm
• Damping Factor >80 @ 8 ohms nominal
• Output: Inverting
• DC offset < 50mV
• Input Connectors Gold plated RCA, Teflon
• Output Connectors Gold plated RCA for audio signal
• Gold plated screw type for GND
• Dimension (WxHxD): 23 x 8,5 x 34 cm.
• Weight: 6 Kg
• Shipping weight: 6.5 Kg
• Power consumption: <80 Watts
• Power Supply: 110/120 Vac or 230/240 Vac 50/60 Hz +/- 10%
• Fuse 2,5 A slow blow type for 230 Vac
• 5 A slow blow type for 115 Vac

All specifications can change without notice