Cosmos ADC | index

Specifications:

Device purpose

/marketing target: ultra-low THD+N Analog to PCM Digital Converter for audio measurement,

DIYers, audio tech bloggers-reviewers

Status: production

Materials: Sandblasted/black anodized aluminum/laser mark/2xES9822Pro/OPA1612/RT6863S

Susumu, Viking resistors, Murata, Samsung C0G caps, Taiwanese connectors/switches

Dimensions: PCBA 90x50x29mm Assembled 104x61x39mm

Weight: PCBA 34g

Assembled 157g

Power: USB-C +5V rail, the second USB connector, <500mA current - power it first.

Cosmos ADC DM has a built-in "thermostat" +TweakCosmosADC_DM.exe control

Input: USB bridge Comtrue CT7601PR(768K) custom FW

XLR L/R (FDA) up to 10Vrms

AUX 2.5mm jack up to 43Vrms

Max DC +/-1V allowed; DC-biased DUT is better to test with Cosmos Scaler

Output: USB-C, PCM up to 32b/768kHz has that connector isolated with 8pF

Please do not use a screwdriver to fix the DATA USB-C cable, use your fingers instead to avoid damaging the USB-C socket.

Latency: 5mS@192k ASIO4ALL REW

measured as a physical delay/2 from ADC input to the 9038D output

Input ranges

/impedance: XLR 1.7Vrms/640Ω; AUX 20.5Vrms/7.8kΩ

XLR 2.7Vrms/1kΩ; AUX 21.5Vrms/8.1kΩ

XLR 3.5Vrms/1.3kΩ; AUX 23Vrms/8.8kΩ

XLR 4.4Vrms/1.66kΩ; AUX 23Vrms/8.8kΩ

XLR 5.3Vrms/2kΩ; AUX 24Vrms/9.1kΩ

The lowest noise sensitivity settings:

XLR 3Vrms/640Ω; AUX 36Vrms/7.8kΩ

XLR 4.7Vrms/1kΩ; AUX 38Vrms/8.1kΩ

XLR 7.7Vrms 1.66kΩ; AUX 41Vrms/8.8kΩ

XLR 9.5Vrms 2kΩ; AUX 43Vrms/9.1kΩ

Note: all voltages listed for -.5dbfs, 0dbfs is 6% higher

unbalanced impedance about 30% less

Frequency response: .8Hz-320kHz @ 32b/768kHz -3db, depends on the interpolation filter setting

SNR=DR@MONO: 129..129.9db(A) grade-B, 130-131.9db(A) grade-A, grace 0 >=132db(A)

"thermostat" =Off (threshold = 255),=On may reduce harmonics but increase the noise

STEREO mode has 3db worse SNR/DR. Measured at 32/48 AP2700

For the MONO mode, please use REW feature Virtual_balanced_input/Sum

ADC DM starts slower than ADC/ADCiso, 3min needed at least, better 10min

Note: Since each unit uses two ADC chips, it is possible to get a combo like

Lch -125db(A)/Rch -128db(A), which means 129.5db(A) in MONO. Such a unit

will get grade B, and it's still cool for measurement

but not much for a STEREO recording.

THD+N@1kHz@-.5dbFS SR48kHz BW 20-20kHz -125db typical for grade-B, -126db grade-A, -127db grade-0
all harmonics level <-140db(typical)

Crosstalk: < -160db@1kHz if not used inputs are shorted

Windows 10 doesn't need the driver but Windows 7 does and the driver installation may require manual installation. So, if you are not ready for that the good idea just update W7 for W10/11.

The Windows driver, Tweak_CosmosADC_DM, FW and extra info are here.

About the TweakCosmosADC_DM.exe

The app is quite similar to TweakCosmos.exe, however, we have a few extra parameters. H5 - 5th harmonic compensation coefficient. It works with adding H3, so we need to compensate H5 first(if necessary, usually zero) and adjust H3 next. H2 and H3 coefficients are 4 times finer than the same from TweakCosmos.exe. INT_SEL_Left/INT_SEL_Right parameters corresponds reg#63;65;67;69(see ES9822.pdf) of Lch/Rch chips. The default value is 187, but sometimes 123 or 251 may reduce noise.

ADC_CONF_Left/ADC_CONF_Right parameters corresponds reg#64;66;68;70. The default value is 224, 56 is more stable, but at the same time it's a noisier value. 112 is perhaps the least noisy but less stable value as well, may improve DR for .5db and more, but you may get one-two glitches per 1-2min. In other words, you can jump from grade B to A if you have no plan to record music(or AVG 5min for a jitter) but THD+N measurement only. The main purpose of Cosmos devices is audio measurement, that's why I added that parameter. Anyway, you should write down the original parameters before the modification.

The next new parameter is ADC_DC_Left/ADC_DC_Right, I do not calibrate that, but you can if you really need a zero DC. 128 is the default.

THERMO_Current is a new control for the "Thermostat" board, the default is 24(about 100mA), and I see no reason to change that current.

THERMO_Threshold is the inverted temperature threshold for the "Thermostat" board, usually, I set it 55 or so. If you need to reduce noise as low as possible, set THERMO_Threshold = 255, and the ADC chip will be cooler. If you have Cosmos APU, you may set the threshold for a higher temperature(THERMO_Threshold =45..50, don't go hotter, please!), and reduce H3 coefficients to obtain the lowest THD.