Just dug out a third amp, class ab, non bridged, amp -/ground to pin 1, amp + to pin 2.
Trying to keep this as simple as possible.
As soon as it hits 6v, that distortion pops up. Nothing to do with the generator, which is clean, as it happens whether I raise the gain on the generator or on the amp.
Trying to keep this as simple as possible.
As soon as it hits 6v, that distortion pops up. Nothing to do with the generator, which is clean, as it happens whether I raise the gain on the generator or on the amp.
I'm interested in more details. Do you have measurements? Their specs aren't better but that tells little. My experience with the Sabre DAC's has not been good and the ESS ADC's were a serious disappointment. if you are talking sound it opens subjective issues.
The single ended input limit will be 1/2 of the differential input with the circuitry in this system. Its mostly limited by the supply rails. Its easy to get higher single ended input range with an input attenuator but the attenuator impedance limits the noise floor. its all a matrix of tradeoffs.
I have more measurements somewhere, but this is the only one I can find at the moment. The 16a, 8a, and 1248 all measure pretty much the same.
The Motu is just ridiculously clean throughout. I was surprised. It just didn't play nice with my ncore amps and had some high freq noise on the outputs.
The rme ufx+ also manages 0.00007% THD and 0.0025% THD+N at -22, where it's ridiculously clean to, then the harmonics start to come up above the noise floor.
At -7 it's down to 0.0003% THD, but 0.0006% THD+N.
The Motu is just ridiculously clean throughout. I was surprised. It just didn't play nice with my ncore amps and had some high freq noise on the outputs.
The rme ufx+ also manages 0.00007% THD and 0.0025% THD+N at -22, where it's ridiculously clean to, then the harmonics start to come up above the noise floor.
At -7 it's down to 0.0003% THD, but 0.0006% THD+N.
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@nyt = we need further information, how the setup is.
What is as signal generator and how you set the output level.
If the signal generator drives the final amp directly (what is the sensitivity of amp input?).
The dummy load (inductance?)
What is your the input attenuation set level on RTX6001.
The last 3 captures after the "Then at varying levels of attenuation" seems OK.
What is as signal generator and how you set the output level.
If the signal generator drives the final amp directly (what is the sensitivity of amp input?).
The dummy load (inductance?)
What is your the input attenuation set level on RTX6001.
The last 3 captures after the "Then at varying levels of attenuation" seems OK.
Dummy load is purely resistive. Happens with or without dummy load. Signal generator is straight from the RTX and is fine, output is clean, and way below max output levels. This will happen even when using a gain knob on the amp, once it hits about 6V, that distortion jumps right up.
The last 3 captures of different attenuation are not ok. You can see the signal level and noise floor change, but the harmonics do not. There are no harmonics actually present in the amplifier's output.
I tested with with 250ASX2, NC400, FP14000, and a little N22. As soon as it hits that 6V mark, the harmonics jump right up.
Right now I have bnc out to rca connected to the N22 input, then N22 output connected directly to pins 2(+) and 1(-) of the input. It's trivial to reproduce. If I use one of my diff probes that output at a fraction of actual voltage and connect that to the RTX, the distortion is gone.
The last 3 captures of different attenuation are not ok. You can see the signal level and noise floor change, but the harmonics do not. There are no harmonics actually present in the amplifier's output.
I tested with with 250ASX2, NC400, FP14000, and a little N22. As soon as it hits that 6V mark, the harmonics jump right up.
Right now I have bnc out to rca connected to the N22 input, then N22 output connected directly to pins 2(+) and 1(-) of the input. It's trivial to reproduce. If I use one of my diff probes that output at a fraction of actual voltage and connect that to the RTX, the distortion is gone.
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I found some more of my images. This is on the output of all the newer Motu interfaces. I got rid of them since they didn't work with my ncore amps (clicking noise), but they worked fine with some other amps I tested with.
Swapped out to the rme ufx+ which has really clean outputs.
The RME guys are really careful in their designs if a little conservative. It looks life the Motu has a grounding issue coupling switcher supply noise to the output. It doesn't show in measurements so it "can't" matter? Clearly it does.I found some more of my images. This is on the output of all the newer Motu interfaces. I got rid of them since they didn't work with my ncore amps (clicking noise), but they worked fine with some other amps I tested with.
Swapped out to the rme ufx+ which has really clean outputs.
I found some more of my images. This is on the output of all the newer Motu interfaces. I got rid of them since they didn't work with my ncore amps (clicking noise), but they worked fine with some other amps I tested with.
Swapped out to the rme ufx+ which has really clean outputs.
What does that periodic burst of energy show?
I had observed something similar on my multichannel DAC through a scope.
Couldn't ever get to the bottom of the issues.
Hi Jens,
Pardon me if its early for these answers.
But wasnt this tested around end points of its specifications?
If this turn out to be a functional bug it will be pretty inconvenient, especially for you and RTX.
Dont get me wrong, i do much appreciate this nicely done product you have made available at a great price for the diy community.
Pardon me if its early for these answers.
But wasnt this tested around end points of its specifications?
If this turn out to be a functional bug it will be pretty inconvenient, especially for you and RTX.
Dont get me wrong, i do much appreciate this nicely done product you have made available at a great price for the diy community.