Issues using E-MU 0404 USB for measurements (ARTA and RMAA)

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maxw

maxw

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Joined 2004
#1
I wanted to be able to measure some equipment so I bought a second-hand E-MU 0404 USB from eBay but seem to have many issues:
  • Left/right levels are hard to match. A very small touch of the line in levels produces big changes in levels in RMAA. Also, the left/right knobs are always at vastly different positions.
  • RMAA doesn't always work, sometimes it crashes and sometimes when you click the Red speaker button to start the test it doesn't actually do anything at all.
  • I get vastly different measurements between left and right. I tried changing cables, switching left and right, still the same. Same in ARTA.
I think some of these issues are just down to RMAA being unstable or buggy but I can also see the vastly different measurements for each channel using ARTA. So I then bought ANOTHER E-MU 0404 USB from eBay, but it has the same issues. I've tried ASIO and MME.

Am I missing something simple here? A setting I don't know about maybe? Or just unlucky with two faulty units?
 

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#6
Have you calibrated your ARTA and EMU? Try a loop back test with a short cable from output to input. Set your ARTA to spa mode in the upper left corner. Adjust levels accordingly for your sound card. I strongly recommend you read the PDF instructions. Post your image of loop back.
 
#7
skidave said:
Have you calibrated your ARTA and EMU? Try a loop back test with a short cable from output to input. Set your ARTA to spa mode in the upper left corner. Adjust levels accordingly for your sound card. I strongly recommend you read the PDF instructions. Post your image of loop back.
Click to expand...

Yes I've calibrated Arta. That RMAA graph I posted was loopback. I see the same results in Arta, it's just that RMAA shows the difference between each channel better than Arta which only does one channel at a time. With ASIO there are no adjustments to make in Windows as it bypasses the level settings. I could post an image but it's just EMU main out > 3.5mm stereo cable > 1/4" mono to RCA adapter > EMU line in.

Perhaps I've just had two faulty units...
 
#8
You have balanced inputs. I would not use a 1/4 mono to RCA adapter. You have Tip (hot) Ring (cold) and Sheild. Your adapter is shorting ring and shield, which works for certain balanced applications... I would connect your positive (hot) signal to Tip and your negative (cold) signal to ring and leave your shield disconnected for now. Run a loop back with that configuration.
 
#11
skidave said:
You have balanced inputs. I would not use a 1/4 mono to RCA adapter. You have Tip (hot) Ring (cold) and Sheild. Your adapter is shorting ring and shield, which works for certain balanced applications... I would connect your positive (hot) signal to Tip and your negative (cold) signal to ring and leave your shield disconnected for now. Run a loop back with that configuration.
Click to expand...
OK I'll test that using a headphone adapter.

skidave said:
Also, don't loop back with IMD. Loop back with a 1K Sine Wave first.
Click to expand...
Although that graph is IMD, all other measurements show the same level of difference, like THD+N.

iko said:
I've seen that kind of graph with bad or badly constructed cables.
Click to expand...
Thanks but I've tried changing cables and switching L/R but there is no change.
 
#14
skidave said:
You have balanced inputs. I would not use a 1/4 mono to RCA adapter. You have Tip (hot) Ring (cold) and Sheild. Your adapter is shorting ring and shield, which works for certain balanced applications... I would connect your positive (hot) signal to Tip and your negative (cold) signal to ring and leave your shield disconnected for now. Run a loop back with that configuration.
Click to expand...
You were right skidave! When I make this change, both channels measure the same. Thanks so much 🙂

Strange this would cause 1 channel to measure poorly but not the other. I only used the 1/4"-RCA adapters because I'd seen them used elsewhere with the EMU 0404, I guess this was foolish.
 
#16
Glad to help. I had a lot of questions about ARTA and interfaces and people here helped quite a bit. I'm glad to give back.

I use ARTA and the EMU 0204. I would be curious to see comparisons between ARTA & RMAA. If you have time to post some screen shots, that would be great. Run some loop backs and generate 1K on each to see how they compare.

Good luck!
 
#17
skidave said:
I would be curious to see comparisons between ARTA & RMAA. If you have time to post some screen shots, that would be great. Run some loop backs and generate 1K on each to see how they compare.
Click to expand...

Sure thing but can you be super specific about what you want? Arta has a million settings and I've only used the Spectrum Analyser mode to see THD and THD+N.
 
#18
Use Spectrum analyzer mode (in ARTA) and on the left, set the source to internal Sine. I don't have ARTA available in front of me, but go to your audio settings and set it to 1Khz. It should default to 1K, but check anyway. Navigating around will give you some familiarity as well.
 
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