Also: the calibration procedure is asking for a sine wave of known voltage from a signal generator.
Would this be sufficient for this purpose? Or, is there an other better option?
Digital DDS Dual-channel Signal Generator Source Frequency Meter Counter 25MHz | eBay
Would this be sufficient for this purpose? Or, is there an other better option?
Digital DDS Dual-channel Signal Generator Source Frequency Meter Counter 25MHz | eBay
Doesn't look likely now, but I would wait to see if Patrick populates a board and is happy with it.
I tried the U-Turn after seeing Mr. Fremer's positive comments and then decided to put a whole minimal $$ system together. It became personal decision to stop chasing some sonic grail. Now I'm waiting to do some comparisons one on one with some guys that are way more serious, I have not done a calibration against what's out there in a long time.
As to your last question, that looks OK remember you are probably more interested in relative measurements like channel to channel match and RIAA conformance relative to whatever the gain is at 1kHz.
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They are poor quality devices. Do some web searches. You need an accurate sine wave of 1K or 400Hz. You could use another PC with audio out and a voltmeter. There are better used sine wave generators out there for sale. Do not use a function generator; spend a few dollars more and get a sine wave generator. Better signal in (when measuring devices) equals better results out.
You should really read the April article I mentioned. Talks about this, a divider and ARTA.
Not really, absolute gain calibration is of minor use. If you think the gain at 1k is 46dB and it's actually 45dB (10% low) it matters little.
You will not find any function generator for little money that delivers a 1kHz sinewave outperforming a soundcard like the emu 0202 or emu tracker.
In a loopback configuration the distortion of DAC-1kHz-output and the distortion of input-PreAmp and ADC sums up in this setup to less than 0.001 % with a sweet spot around 0.0004%.
In a loopback configuration the distortion of DAC-1kHz-output and the distortion of input-PreAmp and ADC sums up in this setup to less than 0.001 % with a sweet spot around 0.0004%.
The calibration is for absolute rms level only the distortion will always depend on the individual test stimulus. I find the rms computation of my cheap OWON scope more than adequate for a sine wave (the distortion has to be gross before it affects the rms level).
I will read it thank you.
I don't know exactly what I'm looking for (read: feeling around in the dark) so recommendations as to what these better generators are would be helpful.
The key consideration for me is small, not cheap or "bad".
Unfortunately good test equipment seems to be generally large and heavy.
I'd like to find a happy place of compromise.
Just an update:
I have not forgotten about this.
I'm working on assembling the soundcard interface by Pete Millet. I was waiting on a few out of stock items from mouser. Hopefully it will be complete this week.
I also pulled the trigger on the cheap Chinese signal generator... I figure it's ok for learning purposes at the moment.
Then, I will be using the scarlet focusrite. I returned the EMU because I was having ongoing driver issues with OSX and didn't want to rely on a 3rd party patch.
So, Phono > Millet Interface > Scarlet Focusrite > Mac Mini running Wine & ARTA
I may still use the inverse riaa or attempt to accomplish it with software.
Either way I think this represents a pretty versatile, low cost introductory test setup.
I have not forgotten about this.
I'm working on assembling the soundcard interface by Pete Millet. I was waiting on a few out of stock items from mouser. Hopefully it will be complete this week.
I also pulled the trigger on the cheap Chinese signal generator... I figure it's ok for learning purposes at the moment.
Then, I will be using the scarlet focusrite. I returned the EMU because I was having ongoing driver issues with OSX and didn't want to rely on a 3rd party patch.
So, Phono > Millet Interface > Scarlet Focusrite > Mac Mini running Wine & ARTA
I may still use the inverse riaa or attempt to accomplish it with software.
Either way I think this represents a pretty versatile, low cost introductory test setup.
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