I have been searching the forum now for more than a few hours and I still cannot find an answer to my question. I have seen the RTX6001, I don't need an oscillator. I have seen the various DAC threads, but I want a turnkey solution. I have also looked at other commercial DAC products for pro audio, but I don't need all of those different connector options.
I am trying to put together a software based FFT solution for ultra low noise shenanigans. I don't think I need a phantom source or any other fancy features, but I do want to achieve very good measurement results with excellent resolution.
My ultra low noise needs are not as important now as I anticipate them being in the future, but I would like to start out with a great interface so that it will not hinder my ability to arrive at those results when needed.
I have an SG505 and 5010 so that covers the source. I would like to use my laptop which is a relatively new MacBook Pro, but I could also use the windows 10 box in the lab. I just need a good DAC interface, so I was thinking about this one:
Amazon.com: Sabaj Da3 Headphone Amplifier Mini Portable Amplifiers Audio Hi-Res High Resolution USB Amp&DAC Native DSD512 32bit/768kHz Dual DAC Grey Color: Home Audio & Theater
The real question is this...............is there anything about this device that would not meet the needs of a great interface for the software?
I just want something that is known to produce EXCELLENT results without any extraneous bells and whistles. What is the latest goto interface for this purpose? Which interface will get me as close to perfect as technology allows? Which NON-AP interface would Samuel Groner or VK choose to measure their oscillators?
Cheers,
David
I am trying to put together a software based FFT solution for ultra low noise shenanigans. I don't think I need a phantom source or any other fancy features, but I do want to achieve very good measurement results with excellent resolution.
My ultra low noise needs are not as important now as I anticipate them being in the future, but I would like to start out with a great interface so that it will not hinder my ability to arrive at those results when needed.
I have an SG505 and 5010 so that covers the source. I would like to use my laptop which is a relatively new MacBook Pro, but I could also use the windows 10 box in the lab. I just need a good DAC interface, so I was thinking about this one:
Amazon.com: Sabaj Da3 Headphone Amplifier Mini Portable Amplifiers Audio Hi-Res High Resolution USB Amp&DAC Native DSD512 32bit/768kHz Dual DAC Grey Color: Home Audio & Theater
The real question is this...............is there anything about this device that would not meet the needs of a great interface for the software?
I just want something that is known to produce EXCELLENT results without any extraneous bells and whistles. What is the latest goto interface for this purpose? Which interface will get me as close to perfect as technology allows? Which NON-AP interface would Samuel Groner or VK choose to measure their oscillators?
Cheers,
David
Not sure what you mean here. The RTX does not have an 'oscillator'. It does have calibrated level switches, which you don't get with typical soundcards.
I must have totally misunderstood the literature. I thought the USB on the back was the connection from the RTX to the computer and the "Generator" section served to provide a leveled signal for stimulation of the DUT. Looking at it more closely now tells a different story. So what is the purpose of the generator section then, if not to stimulate the DUT?
Thank you so much for the course correction.
Cheers,
David
Thank you so much for the course correction.
Cheers,
David
Yes, I did see the Focusrite line and considered the Scarlet Solo, but was hoping for better performance actually. Considering I am going to be using a Twin-T notch filter to null the fundamental I am wondering if the Clarett 2PRE USB would be a solid place to start. The performance is a touch better than the Scarlet, but not by much. This is what I was referring to in my original post. It is tough to find a solid stand-alone unit. Is that why the RTX was started? I am not certain how much they charge for that one?
Any thoughts?
Cheers,
David
Any thoughts?
Cheers,
David
I am not trying to make this so confusing and can now see why such questions are asked.
I have computer
I have monitor
I have a DUT
I have an very clean oscillator
I need to get the data from the output of my DUT to the computer.
I need it to feed the spectrum analyzer software so I can get SOLID & RELIABLE measurements.
I want to use this to further my understanding of ULTRA Low noise design so I would prefer the "Interface" be as clean as is possible.
I hope this helps.
Cheers,
David
I have computer
I have monitor
I have a DUT
I have an very clean oscillator
I need to get the data from the output of my DUT to the computer.
I need it to feed the spectrum analyzer software so I can get SOLID & RELIABLE measurements.
I want to use this to further my understanding of ULTRA Low noise design so I would prefer the "Interface" be as clean as is possible.
I hope this helps.
Cheers,
David
i suggest an interface like a not too vintage emu 0404 that provides 1megohm input to ADC. Modify a standard 10:1 and 100:1 scope probe to get correct hf compensation. Then work on your test environment and software settings to remove all parasitic signals, and get 80kHz flat bandwidth - that learning curve will stand you in good stead imho.
Hey David, i am by no means any expert on this but i recently dipped my toes into the waters with REW. I happen to have two different interfaces that i tried to use for various amp measurements, so i can relate my experiences from this if thats any help.
Now, i don't know exactly what qualifies as ultra low-noise for your purposes.
The noise specification of both scarlett and clarett interfaces is below -128db.
I have a scarlett 18i20 gen2 (which is mains powered), and the noise floor of this is around -140dbFS, see below.
On the other hand, i also tried using my mbox3, which is USB powered. Its noise specification is the same as the scarlett, but it seems a tad cleaner and doesn't have the mains noise (this measurement was done without the laptop plugged to mains).
So from my point of view, the mbox3 offers an excellent measurement system for these purposes, it is also fairly light and very robustly built, and they are pretty cheap used.
Hope that is of use.
Now, i don't know exactly what qualifies as ultra low-noise for your purposes.
The noise specification of both scarlett and clarett interfaces is below -128db.
I have a scarlett 18i20 gen2 (which is mains powered), and the noise floor of this is around -140dbFS, see below.
On the other hand, i also tried using my mbox3, which is USB powered. Its noise specification is the same as the scarlett, but it seems a tad cleaner and doesn't have the mains noise (this measurement was done without the laptop plugged to mains).
So from my point of view, the mbox3 offers an excellent measurement system for these purposes, it is also fairly light and very robustly built, and they are pretty cheap used.
Hope that is of use.
You haven't really specified what you mean by "ULTRA Low noise".
The RTX6001 has a noise floor of 4nV/rtHz, but that's not low enough if you want to measure noise of JFETs, the commercial version will cost you more than USD2K by the way. Most other sound cards will have somewhat higher noise than the RTX, but they're probably good enough to measure the noise of a tube amp.
In any case, if you really need to measure ultra low noise, you should build a LNA, this one will bring you down to 390pV/rtHz, that one is simpler and still can do 1nV/rtHz.
That is very helpful, thank you!!!!
I do like the E-MU 0404, but my concern there is the vintage nature and driver support moving forward. I have read reports that both the USB and PCI version work on Win10, but how long that will be around....is anybody's guess.
Anyhoo, I do appreciate the info and feedback. Is there a list of the Loop-Back performance of these different interfaces on the net?
Keep it coming folks, I would love to dig into this a bit more. Maybe with a few more example plots from other units?
Cheers,
David
I do like the E-MU 0404, but my concern there is the vintage nature and driver support moving forward. I have read reports that both the USB and PCI version work on Win10, but how long that will be around....is anybody's guess.
Anyhoo, I do appreciate the info and feedback. Is there a list of the Loop-Back performance of these different interfaces on the net?
Keep it coming folks, I would love to dig into this a bit more. Maybe with a few more example plots from other units?
Cheers,
David
That is PRECISELY what I am talking about...........GREAT INFO on Groner's Low noise measurement amp!!!! I had been to his site in search of the paper he published regarding an ULN oscillator design, but TOTALLY missed the info on the measurement amp. THANK YOU!!!!
I downloaded the article and related docs from his site and will start digesting them ASAP.
???????????
Building one of these amps to put between the output of my DUT and the input to the "interface" is what will help me get those ULTRA low noise floors in my measurements?
I downloaded the article and related docs from his site and will start digesting them ASAP.
???????????
Building one of these amps to put between the output of my DUT and the input to the "interface" is what will help me get those ULTRA low noise floors in my measurements?
The Samuel Groner LNA has a gain of x1000 and noise floor of 390pV/rtHz, to get the most out of it, you still need a reasonably good sound card that have a noise floor well below 390nV/rtHz.
An onboard PC soundcard probably won't do it, but most of the soundcards mentioned in the posts before is likely good enough.
BTW, if you're interested in the PCB for that LNA, you can PM me.
An onboard PC soundcard probably won't do it, but most of the soundcards mentioned in the posts before is likely good enough.
BTW, if you're interested in the PCB for that LNA, you can PM me.
Perhaps you're fooling yourself to think a system needs to outlast audio and ASIO drivers for Win platforms - by that time other software solutions and diyers would totally cover legacy mechanisms.
You are likely to restrict your measurement performance by using the Tek signal generators, compared to using a nice soundcard where the software will automate all measurements and add so much more convenience and future proofing for new performance. In addition, powering the Tek mainframe would be by mains connection, and so introduce an unwanted earth loop.
I have heard these setups can come with quite a learning curve. I will continue my research and see where I land. I just don't want to spend money "just to get started". and then end up getting another setup when I get going strong with the proper knowledge is all.
I am a "spend the money up front" kinda of person. I spent a long time playing with analog test gear until reality demanded more digital interaction. Then just ended up buying something else that would fill the bill better.
Just trying to minimize wasted time and money is all. Thank you so much for all of the input thus far.
Cheers,
David
I am a "spend the money up front" kinda of person. I spent a long time playing with analog test gear until reality demanded more digital interaction. Then just ended up buying something else that would fill the bill better.
Just trying to minimize wasted time and money is all. Thank you so much for all of the input thus far.
Cheers,
David
You can consider USB card AudioProbe Spartan A [1] as a replacement of E-MU 0404. It has one XLR mic high gain input and one TRS Jack input low gain input.
In the bare state it does not measure great for signals in range -31.5 dBFS and -6.5 dBFS. PWM of LED intensity indicators is modulated to recorded signal. But it can be relatively simply modded to fix the issue.
You can check my measurements[2] and mod instructions kindly provided by AudioProbe support.
[1] http://audio-probe.com/en/product/audio-interface-en/spartan-a-en/
[2] Index of /pub/AudioProbe_Spartan_A
In the bare state it does not measure great for signals in range -31.5 dBFS and -6.5 dBFS. PWM of LED intensity indicators is modulated to recorded signal. But it can be relatively simply modded to fix the issue.
You can check my measurements[2] and mod instructions kindly provided by AudioProbe support.
[1] http://audio-probe.com/en/product/audio-interface-en/spartan-a-en/
[2] Index of /pub/AudioProbe_Spartan_A
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