E1DA APU Cosmos Analog Processing Unit High-Performance Low-noise Pre-Amp

Cosmos APU
Black Housing Unit is assembled and calibrated.
PCBA Only is not assembled/calibrated.
Assembly Kit includes:

 
1) Cosmos APU PCBA not calibrated

2) Wooden box

3) Case extrusion

4) Front panel

5) Rear panel

6) Black silicone legs 4pcs

7) M3 screws 4pcs

8) Black screws 8pcs

9) Red silicone protector for the phantom power

 Specifications:

Device purpose
/marketing target: Cosmos Analog Processing Unit a single-channel device
top performance THD+N and Noise/DR measurement tool for Cosmos ADC
Status: production

Materials: Sandblasted/black anodized aluminum/laser mark/THAT1510/OPA1612/RT6863S
Viking resistors, Murata, TDK, ELNA caps, Taiwanese connectors and switches
Dimensions: PCBA 90x50x29mm
104x61x39mm

Weight: PCBA 34g
Assembled unit 157g

Power: USB-C +5V rail, 350mA idle current, isolated power is recommended
(charger, power-bank >600mA)

Inputs: 3.5mm jacks TRRS pinout as +In/-In/GND/GND respectively
Notch: balanced (FDA) up to 10Vrms(active clamp to 15Vpeak)
gain = 20db + 0/6db(switchable), Zi=20/10kohm bal/unbal
the Notch ratio = -30db at 1kHz or 10kHz(switchable)
Residual Noise 950nVrms(A) typical(gain 20+6db, Fnotch=1kHz)

Residual distortions: @[email protected] 2nd/3rd <-150db/-150db
@1kHz@9Vrms 2nd/3rd <-150db/-160db
@[email protected] 2nd/3rd <-130db/-130db
Residual THD+N BW20-20k@1kHz@9Vrms <-131db unweighted
(practically achieved with DAC+LPF sourse)
@[email protected] <-127db unweighted(practically achieved with DAC+LPF sourse)

Preamp: balanced (FDA) up to 3.5Vrms(10oHm to TVS clamped!), gain = 34/60db
Zi=47/23.5k bal/unbal, 100pF input capacitance i.e. able to use as a phono-preamp
with no RIAA correction, which would be accuratelly applied in a digital domain
Residual Noise <130nVrms(A) typical at +60db gain or <260nVrms(A) at +34db gain

The practically achieved Dynamic Range AES17 in the cascaded Preamp->Notch
@1kHz -60dbfs(10mVrms) >153db(A), @1kHz -60dbfs(5mVrms) >150db(A)
Preamp inputs, just in case, have internal low-noise phantom power 48VDC+/-4V
2×6.8kOhm for use with condenser mics(Neumann, AKG, Rode, and so on).

The phantom power increasing the noise of the Preamp for 12nVrms(A) i.e. 130+12nV

Do not turn On that power without a mic connected, that may damage the device tied to the APU’s preamp input! Please wait for at least 10s after the phantom power is Off, to safely plug/unplug anything to the Preamp input.

Outputs: 3.5mm jacks TRRS pinout as +Out/GND/GND/GND respectively
unbalanced up to 10Vrms, Zo = 47ohm
Frequency response: Notch: 5Hz-200+kHz Fnotch=1k
0db referred to 50Hz 1kHz -30db, 2kHz -0.5..-0.6db, 3kHz -0.2db
Preamp: 10Hz-1MHz+ -3db@60db gain, 10Hz-5MHz+ -3db@34db gain

The calibration file for Cosmos APU 1kHz Notch for REW

Reviews:
https://www.l7audiolab.com/f/e1da-cosmos-apu-2/
https://archimago.blogspot.com/2022/05/early-look-cosmos-apu-high-performance.html

Important notes

Please, before you decide to buy Cosmos APU, make sure that you completely understand what is it. Analog Processing Unit is the first in its kind device on the market, hence, you need to understand do you really want:
a) to do the measurement of your DAC/AMP distortions@1kHz/10kHz at <-150/-130db harmonics level, or THD+N@1kHz down to -132db. In that case, you need the Notch part of Cosmos APU.
b) measuring your DAC/AMP DR/SNR with the residual APU’s noise 130nVrms(A) with the Preamp of Cosmos APU.
c) to rip vinyl records with the Preamp of Cosmos APU + Cosmos ADC with built-in DSP RIAA EQing. Please, check Cosmos ADC page to find the CosmosAdc_v13_RIAA.hex.
d) to use a Pro condenser mic with 48V phantom power with the Preamp of Cosmos APU.

Remember that the input voltage for the APU’s Preamp should be <=3.5Vrms, and <=10Vrms for Notch. Overvoltage of inputs may damage the unit, as a result, usually, input 0603 10ohm resistors will be burned.

Often the 2nd harmonic(H2) APU performance strongly depends on the symmetry of your particular bench/setup, hence, it is a good idea to use a power-bank, USB ISO, or battery-powered laptop for the ADC after APU. Often, a symmetry-related issue would be noticed if H2 levels are different after changing the input polarity.

To avoid accidentally turning On the phantom-power and further damaging the DUT tied to the Preamp input, we placed the blocking red plastic bar into the 48V power switch. Please, take it out before working with a condenser mic. Never turn On the 48V power without a mic but if you did that, please do not insert the plug into the 3.5mm input jack at least 10s after 48V power is Off, or also, you can see the orange LED(48V auxiliary indication)D light inside of the jack, please wait for the light dimming down.