I built a simplified ARTA jig (http://soundhobby.com/measureimpedance.htm) . Whenever I try and calibrate ARTA,, I get a message (difference between channels is more than 2dB ...., check your sound card, cables etc ) or something like that. If you've ever had this message, you'll know what it is.
My configuration was
PC line out -> jig
jig->PC line in
jig->tweeter (I can hear hiss on the tweeter)
I used an 8 ohm resistor because thats what I had around. I know they suggested greated than 10 ohm, but I can't believe this is the issue.
I've checked all my cables, tried patching the line out directly to line in via a miniplug-miniplug connector etc but this issue persists.
Trying the impedance measurements with ARTA uncalibrated , I ended up with a sinusoidal mess.
My line in / line out are not not mute and the levels are equalized. I've tried this on 2 different PCs with the same result.
Help !!
Any ideas.
My configuration was
PC line out -> jig
jig->PC line in
jig->tweeter (I can hear hiss on the tweeter)
I used an 8 ohm resistor because thats what I had around. I know they suggested greated than 10 ohm, but I can't believe this is the issue.
I've checked all my cables, tried patching the line out directly to line in via a miniplug-miniplug connector etc but this issue persists.
Trying the impedance measurements with ARTA uncalibrated , I ended up with a sinusoidal mess.
My line in / line out are not not mute and the levels are equalized. I've tried this on 2 different PCs with the same result.
Help !!
Any ideas.
sorry, It's on the preceding page
http://soundhobby.com/measurementsystem.htm.
I get the same error with / without the jig.
http://soundhobby.com/measurementsystem.htm.
I get the same error with / without the jig.
Are you sure that you are taking the signal to the two input channels from exactly the same source/point ?
Another option is that one of your input channels are defect or has a build in gain mismatch of more than 2 dB.
You could use RMAA for verification of the soundcard and channel ballance with a simple loopback cable
Another option is that one of your input channels are defect or has a build in gain mismatch of more than 2 dB.
You could use RMAA for verification of the soundcard and channel ballance with a simple loopback cable
zobsky said:
Ok, I don't know the software and what calibration procedure they recommend, but I could think of a few things thjat could go wrong:
1. Do you calibrate WITHOUT the speaker connected? You should (probably) have nothing connected when you do calibration.
2. Do you really use only one of the outputs? Using one output for the feedback and the other for driving the loudspeaker could cause strange effects.
3. Is there a balance control on the input of the soundcard. Look in the Windows recording mixer.
4. Cheap soundcards can sometimes be surprisingly poor. Otoh you say that you have tried more than one soundcard so this might not be so likely.
Okay,
RMAA wasn't recognizing the line-in, so I figured something was wrong in software.
I re-installed the drivers on one of the computers (creative audigy 2 ZS platinum) and managed to get RMAA working. I ran the tests via a lineout-linein loopback and everything seemed fine.
I went back to the calibration of the jig and it worked fine this time.
However, when running an impedance plot, I still end up with a mess (see fig). I thought maybe the (8 ohm) resistor was too low so I soldered in a 507 ohm resistor I had (and adjusted the value in the config and re-calibrated accordingly).
Same issue with an graph varying all over the place (I'm testing a cheap 8 ohm tweeter) . The driver is not connected via any amplifier.
RMAA wasn't recognizing the line-in, so I figured something was wrong in software.
I re-installed the drivers on one of the computers (creative audigy 2 ZS platinum) and managed to get RMAA working. I ran the tests via a lineout-linein loopback and everything seemed fine.
An externally hosted image should be here but it was not working when we last tested it.
I went back to the calibration of the jig and it worked fine this time.
However, when running an impedance plot, I still end up with a mess (see fig). I thought maybe the (8 ohm) resistor was too low so I soldered in a 507 ohm resistor I had (and adjusted the value in the config and re-calibrated accordingly).
Same issue with an graph varying all over the place (I'm testing a cheap 8 ohm tweeter) . The driver is not connected via any amplifier.
An externally hosted image should be here but it was not working when we last tested it.
I built the "official" ARTA jig. I'm still having issues (zig zag impedance curves with both pink noise or stepped sine wave), even after re-calibrating the jig (I believe the reference resistor is 27 ohm). Are there any resistance measurements I can make on the jig to verify that I constructed it seperately?
For that matter, I get the crazy curves even when measuring impedance without a driver connected.
Here's a photo of what I constructed (used a cheap $1 plastic box with some ugly holes pre-drilled into it).
With this jig, I'm using my sonic impact amplifier to power the driver under test (a tweeter)
For that matter, I get the crazy curves even when measuring impedance without a driver connected.
Here's a photo of what I constructed (used a cheap $1 plastic box with some ugly holes pre-drilled into it).
With this jig, I'm using my sonic impact amplifier to power the driver under test (a tweeter)
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Henckel said:
I tried setting ARTA sampling rates to 48K and 96K (my soundcard supposedly does 96K) but I still get the same result.
An externally hosted image should be here but it was not working when we last tested it.
I've tried this both ways, .. but should I have the amplifier connected even during the LIMP calibration ?
Okay, I got somewhere.
Looking at the LIMP user guide, it suggested turning off the sound card monitoring control (recording)
My current config is
sound card line out->amp in-> ARTA AMP
ARTA SPEAKER -> speaker
ARTA line in -> sound card line in (see the photo of the black box)
I wonder why the impedance of this tweeter drops with frequency, .. it should rise. Also, the mean impedance should be closer to 8 ohm or below.
Hmmm, .. any ideas?
Looking at the LIMP user guide, it suggested turning off the sound card monitoring control (recording)
My current config is
sound card line out->amp in-> ARTA AMP
ARTA SPEAKER -> speaker
ARTA line in -> sound card line in (see the photo of the black box)
I wonder why the impedance of this tweeter drops with frequency, .. it should rise. Also, the mean impedance should be closer to 8 ohm or below.
Hmmm, .. any ideas?
An externally hosted image should be here but it was not working when we last tested it.
Thanks Sy.
I played around some more, reversing inputs, changing the line-in config on the audigy etc , . .used a 4 ohm woofer too just to be sure.
Well, the woofer curves came out as I would expect them to look, but like the tweeters, the absolute values of the impedances are wrong. I can cheat and correct this situation by changing the configured value of the reference resistor (in this case I reduced it from 27 ohm (which i used when building the circuit to 10 ohm) so that the output of the trace displays something similar to the woofer's nominal impedance ie. 4 ohm . I'm still curious what I'm doing wrong.
The tweeter curves too look a bit better (figure shown with "tweaked" reference resistance value), close to planet10's curves, .. but still not good enough to inspire confidence.
I also tried plugging in a resistor instead of a driver and measuring impedance vs. frequency, .. but I get a wavy line hovering about 0 ohm.
I played around some more, reversing inputs, changing the line-in config on the audigy etc , . .used a 4 ohm woofer too just to be sure.
Well, the woofer curves came out as I would expect them to look, but like the tweeters, the absolute values of the impedances are wrong. I can cheat and correct this situation by changing the configured value of the reference resistor (in this case I reduced it from 27 ohm (which i used when building the circuit to 10 ohm) so that the output of the trace displays something similar to the woofer's nominal impedance ie. 4 ohm . I'm still curious what I'm doing wrong.
The tweeter curves too look a bit better (figure shown with "tweaked" reference resistance value), close to planet10's curves, .. but still not good enough to inspire confidence.
I also tried plugging in a resistor instead of a driver and measuring impedance vs. frequency, .. but I get a wavy line hovering about 0 ohm.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
I guess you have:
1) Run the setup/calibration to get the two channels adjusted to equal values.
2) Entered the value of the reference series resistor under setup/measurement
And I see you have already corrected the first typical fault, by muting the line/mic signals for the PC playback.
Svein B.
1) Run the setup/calibration to get the two channels adjusted to equal values.
2) Entered the value of the reference series resistor under setup/measurement
And I see you have already corrected the first typical fault, by muting the line/mic signals for the PC playback.
Svein B.
Svein_B said:
Thanks Svein,
Yes. I have performed both 1 and 2 . I used line-in1 on the audigy 2 . Line-in2 on this card is on the front panel and is horribly noisy (so noisy as to be practically unuseable, ... shame on Creative for this). I tried using that too but I still have the impedance issues I mentioned.
Is there a set of resistance measurements I can take at the RCA & binding post terminals to verify that I soldered up the jig correctly. It would be really helpful if someone with an ARTA jig could provide this information.
zobsky, in your first post you say that you use PC sound card line-out to your measurement jig. This is really no good. The Line-out signal is too low level, and not enough "drive".
You need to use the speaker output from the PC, or even better run the signal through a proper amp before it hits the jig and speaker.
When this is connected up, run the calibration again to check with the amp and jig, but without any speaker connected.
EDIT: The simple measurement jig linked to is very simple, just a resistor in series with the signal. I would add some attenuating resistors for the signal going back to the PC input in order to be able to use proper levels without overloading the PC line input.
Svein.
You need to use the speaker output from the PC, or even better run the signal through a proper amp before it hits the jig and speaker.
When this is connected up, run the calibration again to check with the amp and jig, but without any speaker connected.
EDIT: The simple measurement jig linked to is very simple, just a resistor in series with the signal. I would add some attenuating resistors for the signal going back to the PC input in order to be able to use proper levels without overloading the PC line input.
Svein.
Svein_B said:
Yes, I know. I only tried the setup without an amplifier to test a tweeter. That's why,over this weekend, I built the "reccomended" jig mentioned on the ARTA website ie. the "measuring box" http://www.fesb.hr/~mateljan/arta/support.htm
tINY said:
I tried measuring the impedance of a resistor and ARTA gives me , .. . noise, close to 0 ohm . (I used another 27 ohm resistor I had as the test resistance with the switch set to "measure impedance"). I'm puzzled by this, I would've expected a straight line (constant impedance vs. frequency)
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