Interporation and Impulse
Hello Javin5,
I think you are selecting digital filter's transmission characteristic of Interpolation Digital Filer.
Please see attach file, I like "Sharp Roll off mode", no amplitude modulation.
If we hear music signal that fs=44.1kHz data, I would like to choice well stopband attenuation Digital Filter.
On slowroll of mode, if we hear music signal that fs=32kHz data, much more can we hear "Remaining Image Noise"?
Javin5 said
>This is really simple to verify. Play your 20 kHz tone and check the output of the Buffalo/IVY with a scope.
>If you see a clean sine wave, you have very little or no aliasing.
>
>Since no ADC or sampling is involved this way, you can be sure that what you see is what you get.
>Attached is the output I got this way on an old Tektronix scope.
>The upper trace is the output of the HK player and the lower trace is the output of the Buffalo/IVY.
>This is in agreement with my FFT's.
Hello Javin5,
I think you are selecting digital filter's transmission characteristic of Interpolation Digital Filer.
Please see attach file, I like "Sharp Roll off mode", no amplitude modulation.
If we hear music signal that fs=44.1kHz data, I would like to choice well stopband attenuation Digital Filter.
On slowroll of mode, if we hear music signal that fs=32kHz data, much more can we hear "Remaining Image Noise"?
Javin5 said
>This is really simple to verify. Play your 20 kHz tone and check the output of the Buffalo/IVY with a scope.
>If you see a clean sine wave, you have very little or no aliasing.
>
>Since no ADC or sampling is involved this way, you can be sure that what you see is what you get.
>Attached is the output I got this way on an old Tektronix scope.
>The upper trace is the output of the HK player and the lower trace is the output of the Buffalo/IVY.
>This is in agreement with my FFT's.
Attachments
Hi Nagaesan
Thanks for your input. I'm aware of the interrelations beween rolloff, impulse response and aliasing. Unfortunately, changing the filter switch on my board doesn't seem to work. However, Brian is now sending me new firmware and some new parts.
I agree with you, I also think that in the case of CD, the fast rolloff is preferable.
Are the wave forms in your image from the sabre chip?
Kurt
Thanks for your input. I'm aware of the interrelations beween rolloff, impulse response and aliasing. Unfortunately, changing the filter switch on my board doesn't seem to work. However, Brian is now sending me new firmware and some new parts.
I agree with you, I also think that in the case of CD, the fast rolloff is preferable.
Are the wave forms in your image from the sabre chip?
Kurt
Impulse response and roll off
Javin5,
Sharp roll off is TPC DAC1.5(PMD-100).
This FIR filter is 8fs, that is "cascaded type"
The input data is 44.1kHz(1fs), first step interpolation FIR filter's output is 2fs.
And second FIR's output is 4fs.
And final FIR's output is 8fs.
That impulse of slow rolloff is WADIA64.4(AT&T DSP16x4).
This FIR filter is very low taps 16fs, but this is not "cascaded type"
The input data is 44.1kHz(1fs), FIR filter's output is 16fs, only one step.
WADIA's responce is -2.7dB@20kHz(fs=44.1kHz), because very low taps FIR,but sounds( low power energy over 16kHz) good.
By the way, Javin5.
That Impulse source is TESD CD data, made by computer.
If I made Impulse data using A/D converter, and If I playback this impulse data with slow rolloff or sharp roll off, we always see ringing Impulse response.
But DENON's "ALPHA processed interporation" is "no ringing" when playback Impulse data made by computer.
I think this is DENON's great joke.
Javin5,
Sharp roll off is TPC DAC1.5(PMD-100).
This FIR filter is 8fs, that is "cascaded type"
The input data is 44.1kHz(1fs), first step interpolation FIR filter's output is 2fs.
And second FIR's output is 4fs.
And final FIR's output is 8fs.
That impulse of slow rolloff is WADIA64.4(AT&T DSP16x4).
This FIR filter is very low taps 16fs, but this is not "cascaded type"
The input data is 44.1kHz(1fs), FIR filter's output is 16fs, only one step.
WADIA's responce is -2.7dB@20kHz(fs=44.1kHz), because very low taps FIR,but sounds( low power energy over 16kHz) good.
By the way, Javin5.
That Impulse source is TESD CD data, made by computer.
If I made Impulse data using A/D converter, and If I playback this impulse data with slow rolloff or sharp roll off, we always see ringing Impulse response.
But DENON's "ALPHA processed interporation" is "no ringing" when playback Impulse data made by computer.
I think this is DENON's great joke.
Well if I could vote to shape the future of the mod version I would want DSD, no regs(using shunts), no I/V(using D1), still have the best layout and maybe microprocessor on-board. I think if you are going to add regs, many will bypass them unless they are the best. If you put an I/V on it will just get in the way of those wanting to just use it in voltage mode or an outboard I/V. I think the best option would be to make it as simple and cheap as possible with the necessary pads for the regs, output, input, etc.
I have a question about the I2S input impedance at the Buffalo.
I take the I2S signal from the Juli@ soundcard. A friend told me to put (3x) low ohms resistors in serie of the signal I2S wires and to do this in the pc at the juli@ to avoid the effect of ringing causes by impedance mismatch. I did it (33ohm) and the result was unexpected positive; more fluid sound, less stress.
Do you guys have any thoughts about how to calculate or measure the optimum resistor value?
I take the I2S signal from the Juli@ soundcard. A friend told me to put (3x) low ohms resistors in serie of the signal I2S wires and to do this in the pc at the juli@ to avoid the effect of ringing causes by impedance mismatch. I did it (33ohm) and the result was unexpected positive; more fluid sound, less stress.
Do you guys have any thoughts about how to calculate or measure the optimum resistor value?
Is there DC offset in SE mode - ie would it need a cap on the output like the earlier beta boards (beta-beta!)?
I only ask because there was meant to be fairly severe turn-off thump on that too but I have none. And I mean none at all.....I have a friend who has the same DAC and would love a counterpoint set up (I and he thinks it sounds great) but uses SE outputs only.
And the 2 boards would run happily off a single LCDPS?
Fran
I only ask because there was meant to be fairly severe turn-off thump on that too but I have none. And I mean none at all.....I have a friend who has the same DAC and would love a counterpoint set up (I and he thinks it sounds great) but uses SE outputs only.
And the 2 boards would run happily off a single LCDPS?
Fran
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