I still use the EMU-202. I observed a lot rf-noise when watching the output with a scope - but I attributed this to DAC residual outband noise. Whatever - it did not interfere with any of my audio measurements until now.
Member
Joined 2008
For anybode, who are already have a scope probes, this maybe better:
BNC DC Male Female to RCA Coupler Connectors Plug Joiner CCTV Camera Video Balun | eBay
(select "BNC Female to RCA Male")
If you only need a square wave, almost all oscilloscopes have a .5V fast rise time square wave
output for probe calibration.
output for probe calibration.
The downside is lack of protection and attenuation options using a scope probe designed for 1 Meg inputs on a sound card. The probe above seems pretty well designed with internal voltage limiting and appropriate switch options. And pretty reasonably priced.
Actually there are a number of good options to do some limited testing pretty cheaply.
I've used cheap ebay 1x/10x and 100x scope probes working in to a 1Meg unbalanced 'instrument' input on EMU0404. For extended raw high frequency response of soundcard (ie. for 96kHz bandwidth) the probe's compensation needs to be adjusted in loopback (soundcard equivalent to a scope probe cal), and may benefit from some internal surgery to remove a shunt loading capacitor. I've found the 100x probe excellent for valve amp work, but always conscious that it is not meant for anode or B+ type level probing. I use a 1/4" to RCA adaptor, followed by the RCA to BNC adaptor for a solid shielded interconnect between scope probe and interface. For more mundane testing like of speaker outputs, a 10x probe may be sufficient, or a fixed resistor divider. I agree that they don't offer bullet-proof clipping protection, but for an interface with input gain control and level indication, and good bench awareness of what is being probed and the risk of high signal levels, imho it avoids any concern about the clipping mechanism.
I'm beginning to think the $20 generator is an eBay scam. That generator usually sells for $100 on eBay. I have had no reports from the seller that it has been shipped which I should have by now. Also only 2 reports from buyers both of which are suspicious. The generator is valid but a different issue at $100 from the normal sellers vs. $20. I'll report back if it seems the seller turns out to be a scammer.
I've generally found it impractical for X-Y plots to identify phase shift accurately other than for 0, 90, 180 degree type shifts, and to identify a 'shift direction' if say passing through 90 deg and then back again through 90 deg but not actually reaching 180 deg. The main hassle in achieving any accuracy more than perhaps 'circa 30deg' or 'circa 60deg' is that amplitude of an 'output' signal is typically changing as frequency is being swept so the shape being assessed is a changing ellipsoid.
That can make it difficult to discern the level of any phase shift improvement at a particular frequency if say a circuit change has been made, especially if the phase shift improvement being assessed is likely to give only 15-30 deg change.
The phase measurement situation is exacerbated when distortion becomes significant, such as if output transformer related distortion imposes itself at low frequency.
That can make it difficult to discern the level of any phase shift improvement at a particular frequency if say a circuit change has been made, especially if the phase shift improvement being assessed is likely to give only 15-30 deg change.
The phase measurement situation is exacerbated when distortion becomes significant, such as if output transformer related distortion imposes itself at low frequency.
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Member
Joined 2008
⚠️⚠️⚠️ YOU ARE RIGHT 1audio!
tried to buy it but ebay says the seller doesn't accept payments - i also tried to get in contact with the seller but no answer.
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Get the right tool for the right job :
Hardware
– QuantAsylum
affordable , and very very useful 😉
and if money is not an issue AP is your friend 😀
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Hardware
– QuantAsylum
affordable , and very very useful 😉
and if money is not an issue AP is your friend 😀
.
1audio
I bought this 60MHZ version about 1 1/2 years ago for $127CDN about $90US back then. its a bit more expensive now. $142US plus $35 for shipping. Mine was shipping included.
price has gone up a lot.
FY6900-20/30/40/50/60M DDS Signal Generator 0.01-60MHz Arbitrary Waveform K K | eBay
I bought this 60MHZ version about 1 1/2 years ago for $127CDN about $90US back then. its a bit more expensive now. $142US plus $35 for shipping. Mine was shipping included.
price has gone up a lot.
FY6900-20/30/40/50/60M DDS Signal Generator 0.01-60MHz Arbitrary Waveform K K | eBay
I have the same function generator, it's sold by several brands, so I picked the cheap one with the crummy case. I see yours has a much nicer case...
It works, the output has a bit of HF noise, and the DAC is a bunch of resistors connected to the CPLD pins. So it won't have stellar distortion. But it's absolutely usable. No complaints, considering the price.
Uni-T UTG962E is a cheap alternative with a real 2 channel DAC.
It works, the output has a bit of HF noise, and the DAC is a bunch of resistors connected to the CPLD pins. So it won't have stellar distortion. But it's absolutely usable. No complaints, considering the price.
Uni-T UTG962E is a cheap alternative with a real 2 channel DAC.
Thanks for the reference. I don't need another function generator, I have 3 but for $20 I thought it might be useful.
OK, I figured out the difference: the front panel is the same, but yours has real DAC chips instead of crummy resistors and a frequency counter. It's a nice deal.
Here's the cheap version with the ugly case.
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@fabrice63 - I came to the same conclusion, I have the QA402 on my list. Thinking ahead, I could see myself buying lots of nearly good enough stuff, and not being fully happy, so personally I would rather wait until I really need something and spend a little more on something specifically designed for testing audio equipment. Plus, I don't want to blow up my PC if I use a standard soundcard. It comes with its own software, and can be used with other software also.
I looking to see if I can use the QA402 with a Mac also. Going to keep researching, until I'm totally certain.
Heres is a getting started guide to get a feel for how it can be used.
Getting Started * QuantAsylum/QA402 Wiki * GitHub
As the QA402 is new, I am waiting until any issues have been ironed out.
Also waiting until issues with cross platform software have been fixed.
I think there are quite a few threads here about the QA401 previous model. But I found that these are quick advanced discussions, so I'm happy to see that QuantAssylum have a wiki up, that walks you through doing measurements. At the moment to the wiki only shows frequency response measurements, but hopefully to they will show a walkthrough of doing THD and more.
Getting Started * QuantAsylum/QA402 Wiki * GitHub
As the QA402 is new, I am waiting until any issues have been ironed out.
Also waiting until issues with cross platform software have been fixed.
I think there are quite a few threads here about the QA401 previous model. But I found that these are quick advanced discussions, so I'm happy to see that QuantAssylum have a wiki up, that walks you through doing measurements. At the moment to the wiki only shows frequency response measurements, but hopefully to they will show a walkthrough of doing THD and more.
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A few years ago when the first version of the QA400 came out, I asked them how to script it with Python and if it was seen by the PC as a soundcard so I could use any other software (including mine) and not just their own. The answer to both was "why would you want to do that" so I did not investigate any further.
There is an unofficial ASIO driver now though, so that might have been fixed.
There is an unofficial ASIO driver now though, so that might have been fixed.
This was an very good question 🙄
if you have your own software , why dont you build your own hardware 😉
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I thought about it, but there are nice soundcards available on the market you know?
Streaming audio data with ASIO is extremely easy.
Besides, the "why would anyone want to do that" answer contains a lot of useful information about the designers of said product.