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Old 3rd February 2009, 08:00 AM   #1
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Default Issues with Emu tracker and THD measurements

Hi Folks,

i have a problem that i can't figure out.
I recently bought an external soundcard: EMU Tracker PRE.

Just a quick note for who would like to buy it: Don't!

The company is having some serious problems and apparently they don't have a customer service anymore.
They supposedly deal through their website: but they really don't!


I was planning on use the EMU along with SpectraPlus to make THD analysis.

Unfortunatelly with Vista, I couldn't set sampling rate over 44.1KHz, so I had to install XP and finally i could freely choose whatever sampling rate was avaliable.

Interesting aspect is that analysis performed on XP and Vista, for the same parameters, showed DIFFERENT results! (?)


Anyways, in both cases, SNR, seemed to be below specifications.

Therefore i have hooked the output of the soundcard to the oscilloscope to check if there was anything wrong with that.
Surprisingly i got 200mV of output noise!

Since i don't have a spectrum analyzer, I had to arrange an LPF and adjust for frequency to see if the noise was entirely outside audio band or not.
Unfortunatelly with a 20KHz LPF cut frequency, the output noise is reduced, but not gone (still 30mVpk-pk !).

Strange fact though is that, if i try to connect an headset or hook it to my stereo system i don't hear any strong noise (acytually just a very little smaaaaall hiss on the tweeter with the ear by the speakier).

I am going to attach an URL with pictures of the set up used for the self test, screenshoots of settings on SpectraPlus and of the self-loop-test and a picture of the output noise.

http://s678.photobucket.com/albums/vv147/Stefanoo_2009/

I sincerely don't know if the card is defective or not.

If you guys have any kind of advice, please feel free to post here.

Thank you very much in advance for the attention paid.


Best,
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Old 4th February 2009, 04:18 AM   #2
Salas is online now Salas  Greece
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I get a far worse tracker pre self loop test myself! Be happy!
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Old 4th February 2009, 07:27 AM   #3
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would you mind posting your results (screenshoot of Spectraplus and picture of your set up)?
Since this soundcards are standard products I don't think an item can consistently differ from another (for same settings and same program management).
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Old 4th February 2009, 08:03 AM   #4
PMA is offline PMA  Europe
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Your result is very good, I would say. Do not forget that SNR is calculated over whole band (i.e. 24kHz in your case) and includes distortion! (that's how the SW works).

In case you want to know SNR, measure at -60db input signal level and add 60dB to SNR reading. This is also the method recommended by standards.
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Old 4th February 2009, 08:33 AM   #5
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Default Emu tracking

From memory I clocked these ones at 45 or 50kph.
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File Type: jpg emu.jpg (37.9 KB, 1538 views)
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Old 4th February 2009, 08:50 AM   #6
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Default Costruire audio amplificatore di potenza per tuo suonno


Is a very good idea too

"building audio amplifiers"

arrivederci fratello

Carlo
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Old 4th February 2009, 09:28 AM   #7
PMA is offline PMA  Europe
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Default Re: Emu tracking

Quote:
Originally posted by G.Kleinschmidt
From memory I clocked these ones at 45 or 50kph.
They seem to keep direction according to street marking
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Old 4th February 2009, 09:33 AM   #8
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Quote:
From memory I clocked these ones at 45 or 50kph.
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Old 4th February 2009, 10:55 AM   #9
fotios is offline fotios  Greece
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Hi Stefano

I have the EMU 0404, which is same in performance with Tracker, except than it offers more possibilities like phantom power, led bargraphs etc. You must know probably. The main issue is that EMU0404 and Tracker have the same maximum 24bit/196KHz rates, as well the same distortion etc.
I have bought the "Virtins M.I. Pro3" and i have tried "Spectra Plus" also with my EMU.
I can confirm you that with both softwares, these cards can operate at their MAXIMUM RATES with amazing good results and that their performance is a little worse from professional spectrum analyzers. Don't believe those replies that are written from other people. Me, in this forum and at the moment, i am the only that i have tried the possibilities of these softs in conjuction with EMU in practice.
The secret to you get these maximum rates, simply it is the O.S. of your PC as well the installed DRAM. To the present, the most reliable OS for such type rates, is the WinXP x64 (NOT 64bit VISTA). Yes, a 64bit OS, in conjuction with 8GB DDRAM (x64 can manage up to 128GB DRAM instead WinXP) can run these applications ON THE FLY without the need of use the swap file. Only under this way you can run analysis in 24bit/196KHz which gives BY FAR BETTER AND RELIABLE RESULTS from 32bit systems. If your PC can't run x64, then you must do an upgrade.
Because i had the same problem like you with Virtins MI Pro 3, after enough e-mail exchanges with the company, we had resulted in this solution described above.
The same suggestion i received from Visionics because the simulator of my EDA software EDWinXP 1.5 presented hang-ups.
Thus, i was forced to built a new PC pure 64bit before one year (its cost was then 850 euros, now must be arround 300 euros as much) and when this done, then everything went well.
I got my "doct" diploma after one year of continuous trials and study on these systems.
You may ask Virtins Tec. for Fotios Anagnostou from Greece, to will get a confirmation for those i wrote above, that they are real and not aerology.

Regs
Fotios
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Old 4th February 2009, 12:41 PM   #10
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Hi,

thank you very much for your anwer.
You described the problem very well.

I can't run X64 since i have a 32bit uP (dual core T2450 2GHz) too bad!
I might consider as a future upgrade what you've just suggested.

I have noticed, speaking of different performance on different plattforms, that i get better results on Vista than on XP for the same settings.

I wil start playing around with the card and maybe i will post some autoloop tests on this 3d....in case anybody would like to compare results.
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