baudline
Home
News
What is baudline?
Screenshots
Download
FAQ
Manual
Search
Solutions
Mystery Signal
Contact
Information
ESS Maestro 2E


vendor ESS Technology
product Maestro 2E
interface chip on Compaq Armada M300 motherboard
duplex full
channels 2
resolution 16 bits
max rate 48 Ksample/sec
codec ES1978
operating system Mandrake 9.0 Linux x86 2.4.19
driver maestro OSS 3.8.2
buffer size input 32 KB, output 32 KB
test date Sep 26 2005
notes Only input is a mono microphone jack.  No internal mixer loopback.  Machine not NTP disciplined.

Set mixer output "Volume" to maximum with an external mixer program.


This card is part of the Full Duplex DAQ comparison survey.

 
Sample Rate
The sample rate on DAQ cards is not a fixed absolute constant.  Like time, it fluctuates, and it is difficult to measure accurately.  Sometimes there are relationships between the input and output sample rates that can reveal interesting details about the inner working machinery.

The following table of measurements use a technique described in the sample rate stability application note. The rate column is the sample rate value that the collection hardware is programmed to.  The in/out rate and in/out error columns are absolute measurements of the ADC / DAC clock.  The loop error column uses a tone generator loopback method for a high accuracy measurement of the relative difference between the ADC and the DAC clocks.  The three error PPM columns are theoretically related by the formula: "in_error - out_error = loop_error"

rate in rate out rate in error out error loop error
4000 3931.714 3931.718 -17071.5 PPM -17070.5 PPM +0.0000 PPM
5510 5416.360 5416.383 -16994.6 PPM -16990.4 PPM +0.0000 PPM
8000 7864.158 7864.179 -16980.2 PPM -16977.6 PPM +0.0000 PPM
11025 10837.84 10837.88 -16976.0 PPM -16972.3 PPM +0.0000 PPM
12000 11796.60 11796.64 -16950.0 PPM -16946.7 PPM +0.0000 PPM
16000 15728.32 15728.34 -16980.0 PPM -16978.8 PPM +0.0000 PPM
22050 21676.43 21676.46 -16942.0 PPM -16940.6 PPM +0.0000 PPM
24000 23593.21 23593.25 -16949.6 PPM -16947.9 PPM +0.0000 PPM
32000 31457.38 31457.48 -16956.9 PPM -16953.8 PPM +0.0000 PPM
44100 43352.86 43352.97 -16942.0 PPM -16939.5 PPM +0.0000 PPM
48000  47185.71  48000.94  -16964.4 PPM  +19.5833 PPM  -16991.0 PPM 


The ESS Maestro 2E has an extremely large absolute sample rate error of about -17000 PPM.  This error is consistent at all sample rates except 48000 where the out error is +19.58 PPM.  Why does one rate have a very high tolerance and all of the other rates are so wrong?

Except for 48000, all of the other sample rates have a loop error of zero PPM.  This means that the input and the output clocks are locked together while the absolute rates have a large error.

All sample rates have nice clean rate convergence plots that are smooth and free from any discontinuities. 

 
Frequency Domain
The sound card's input and output jacks are connected with a short external cable and run in full duplex mode.  This is a loopback test and baudline's tone generator is the signal source.  Distortion, noise floor, filter response, and inter channel crosstalk are the frequency domain measurements of interest in this section. 

The signal test sources are a pure sine wave, a linear sine sweep, and WGN.  The sine wave is used for the distortions and crosstalk measurements.  The linear sine sweep and WGN are used for the filter characterization measurement.  Both are an application of the swept sine vs. WGN technique and are equivalent measures of the frequency response. 

Since spectral performance is a function of sample rate, each of the sound card's native rates will be tested.  The highest sample rate is usually the cleanest and this is advantageous because it allows the isolated testing of the ADC and the DAC.  The matched, source, and sink sample rate combinations are described below.

matched
The input and output sample rates are the same.  This combination tests the performance of both the ADC and the DAC in a matched mode of operation.  The linear sine sweep signal in the left spectrogram display and the WGN (orange) in the Average window characterize the in-band filter response.  The sine wave (green) in the Average window is used for distortion and crosstalk measurements.  The sine leakage (purple) is used for crosstalk measurement

The matched spectral runs were so poor at all sample rates that an iMic v3.00 was inserted into the test chain.  The iMic v3.00 has very good ADC and DAC stages and it is an ideal tool to further investigate what is going wrong with the ESS Maestro 2E.  The iMic v3.00 was used as the source and the sink as an accurate control.

source
The iMic v3.00 at the 48000 sample rate was used for test signal capture purposes.  The Maestro 2E is the source while the iMic is the sink.  This combination tests the performance of the Maestro 2E's DAC.  The linear sine sweep signal in the middle spectrogram display characterizes the DAC filter response.  The position of the pass-band and the stop-band filter transition is defined by the Nyquist frequency of the DAC.  The noise floor (purple) is either the Average collection of a silent channel or the crosstalk channel depending on sample rate.

sink
The iMic v3.00 at the 48000 sample rate was used for test signal generation.  The iMic is the source while the Maestro 2E is the sink.  This combination tests the performance of the Maestro 2E's ADC.  The linear sine sweep signal in the rightmost spectrogram display and the orange curve in the Average window below it characterize the ADC filter response.  The position of both the pass-band and the stop-band filter transition is defined by time in the spectrogram and by folded frequency in the Average window.  The orange Average curve represents the pass-band while the cyan curve is a folded representation of the stop-band ADC filter response.  The noise floor (purple) is the crosstalk channel.

The naming convention for the columns below is (DAC -> ADC) where DAC represents the source sample rate and ADC represents the sink sample rate. 


matched
source (DAC)
sink (ADC)
4000 -> 4000 4000 -> 48000 48000 -> 4000


5510 -> 5510 5510 -> 48000 48000 -> 5510


8000 -> 8000 8000 -> 48000 48000 -> 8000


11025 -> 11025 11025 -> 48000 48000 -> 11025


12000 -> 12000 12000 -> 48000 48000 -> 12000


16000 -> 16000 16000 -> 48000 48000 -> 16000


22050 -> 22050 22050 -> 48000 48000 -> 22050


24000 -> 24000 24000 -> 48000 48000 -> 24000


32000 -> 32000 32000 -> 48000 48000 -> 32000


44100 -> 44100 44100 -> 48000 48000 -> 44100


48000 -> 48000 48000 -> 48000 48000 -> 48000


Severe crosshatch aliasing is seen at all sample rates in the matched column.  The source spectrogram sweep at 48000 is very clean.  The DAC filter have 25 dB stop-band attenuation at the lower rates.  The ADC anti-aliasing filter is nonexistent at all sample rate except for 32000 and 44100 were it is extremely poor.

Notice the strong 1000 Hz tone and it's harmonics in the noise floor (purple) curves of the source and sink columns.  They are artifacts from the iMic and can also be seen on the iMic v3.00 page.



distortion matched
The following table of measurements were made using the technique described in the sine distortion application note.  It is a full duplex test that uses a loopback of the tone generator to measure the various distortion parameters.  The stereo crosstalk column is a measure of channel leakage that uses a sine wave channel and a silent channel as the signal sources.

rate SNR THD SINAD ENOB SFDR crosstalk
4000 +46.01 dB -52.58 dB +45.14 dB +7.206 bits +50.74 dB -59.09 dB
5510 +42.70 dB -52.92 dB +42.30 dB +6.734 bits +47.59 dB -61.50 dB
8000 +39.08 dB -50.22 dB +38.76 dB +6.145 bits +43.98 dB -64.29 dB
11025 +36.19 dB -54.00 dB +36.12 dB +5.707 bits +41.15 dB -65.68 dB
12000 +35.58 dB -50.45 dB +35.44 dB +5.594 bits +40.68 dB -66.30 dB
16000 +33.10 dB -48.55 dB +32.98 dB +5.185 bits +38.47 dB -67.10 dB
22050 +30.05 dB -47.36 dB +29.97 dB +4.685 bits +34.85 dB -68.39 dB
24000 +29.50 dB -46.24 dB +29.41 dB +4.592 bits +34.41 dB -68.55 dB
32000 +22.65 dB -26.10 dB +21.04 dB +3.201 bits +26.98 dB -68.55 dB
44100 +18.49 dB -30.94 dB +18.25 dB +2.739 bits +29.05 dB -67.50 dB
48000  +17.70 dB  -30.52 dB  +17.48 dB  +2.611 bits  +25.62 dB  -66.47 dB 




distortion source(DAC)
The same distortion measurement technique as above but the iMic v3.00 was used in the sink position.  This table represents the distortion created by the ESS Maestro 2E's DAC.

rate SNR THD SINAD ENOB SFDR crosstalk
16000 +34.81 dB -63.33 dB +34.80 dB +5.488 bits +36.46 dB -73.54 dB
22050 +43.01 dB -63.27 dB +42.97 dB +6.845 bits +43.97 dB -73.64 dB
24000 +46.83 dB -64.25 dB +46.75 dB +7.473 bits +49.45 dB -72.72 dB
32000 +47.30 dB -64.85 dB +47.23 dB +7.552 bits +50.13 dB -72.75 dB
44100 +51.79 dB -65.14 dB +51.60 dB +8.277 bits +54.78 dB -72.79 dB
48000  +71.92 dB  -65.77 dB  +64.83 dB  +10.475 bits  +68.58 dB  -73.64 dB 




distortion sink(ADC)
The same distortion measurement technique as above but the iMic v3.00 was used in the source position.  This table represents the distortion created by the ESS Maestro 2E's ADC.

rate SNR THD SINAD ENOB SFDR
4000 +44.66 dB -59.73 dB +44.53 dB +7.103 bits +50.15 dB
5510 +42.02 dB -58.83 dB +41.93 dB +6.673 bits +47.28 dB
8000 +38.85 dB -56.67 dB +38.78 dB +6.148 bits +43.97 dB
11025 +36.15 dB -54.25 dB +36.09 dB +5.702 bits +40.96 dB
12000 +35.45 dB -49.57 dB +35.29 dB +5.568 bits +40.59 dB
16000 +33.15 dB -44.14 dB +32.82 dB +5.158 bits +37.88 dB
22050 +30.21 dB -47.26 dB +30.13 dB +4.712 bits +35.02 dB
24000 +29.36 dB -48.34 dB +29.30 dB +4.574 bits +34.31 dB
32000 +27.24 dB -37.00 dB +26.80 dB +4.159 bits +31.75 dB
44100 +24.12 dB -41.03 dB +24.04 dB +3.700 bits +29.47 dB
48000  +23.36 dB  -40.56 dB  +23.28 dB  +3.574 bits  +28.12 dB 



The matched and sink(ADC) distortion performance of the Maestro 2E card is horrible.  This is caused by the lack of ADC filters on the Maestro 2E.  Since the ADC filters are the limiting factor, The matched and the sink runs have very similar distortion measurements.  It is also interesting the SNR, THD, SINAD, ENOB, and SFDR all steadily improve as the sample rate decreases.  From 48000 to 4000 the ENOB improves by 4.6 bits.

The source(DAC) distortion performance of the Maestro 2E at the 48000 sample rate is fairly good and it is tolerable at the 44100.  The source distortion measurements degrade in quality as the sample rate decreases.

 
Quantization
A white Gaussian noise signal source was generated and captured in full duplex loopback fashion at each of the standard sample rates.  The Histogram plots below show a unique sample distribution that is dependent on sample rate.

4000 ... 12000

The 4000 to 12000 samples are a variation of the above histogram.  The left and right channels alternate as the most prominent which is cause by a slight gain mismatch.

16000 ... 48000

All sample rates greater than 12000 look like the above histogram.  The strong DC spike is a round to zero error and it has a height of 66%.  The 3:1 percentage would fit the rounding rule of truncation, that is, values between -1. and +1 go to zero.

 
Channel Delay
A sine wave signal was generated and captured in full duplex loopback mode.  The time domain response was observed with the Waveform window where the green curve represents the left channel and the purple curve represents the right channel. 



This is a 3 or 4 sample inter channel delay.  The delay becomes less as the sample rate decreases.  Below the 32000 sample rate the delay is about one sample.

This phenomena is not a function of frequency so it is a delay and not a phase shift.

 
Analysis
The ES1978 has a -17000 PPM rate error at almost every sample rate, massive harmonic distortion, nonexistent filters, extremely poor distortion measurements, a DC quantization spike at bin zero, and a couple sample inter channel delay.

This chip has a lot of problems it is looks like they are all related.

 
Conclusion
The performance of the ESS Maestro 2E chip is horrible except for DAC operation at the 48000 sample rate.

For playback at 48000 the ENOB is +10.475 bits and the sample rate error is +19.5833 PPM.  The Maestro 2E's DAC performance at 48000 is fairly good.   Unfortunately playback at 48000 is the only good thing about the Maestro 2E.

DAC playback at 44100 is tolerable with an ENOB of +8.277 bits but the output sample rate error is -16939.5 PPM.  Such a large sample rate error will drastically change the tuning of MP3 music playback.  A440 would become A432.5 which is -30 cents (third of a semitone).

The ADC anti-alias filters are nonexistent on the Maestro 2E so recording is not recommended.

Copyright © 2005 SigBlips.com - group - blog - site map