Hello friends, this is my first time I'm doing measurements justMLS and although I read the manual and I've been looking through the forums, I need your help to know that I am going in the right direction.
The hardware used for measurements is:
Targeta Esi juli@ sound.
microphone preamp M-Audio mobile pre usb.
Behringer EMC8000 microphone.
20W amplifier.
Jig, which I built, designed by John K., this is where the link is: http://www.htguide.com/forum/showthread.php4?t=26766&page=1&pp=35
Images of these measurements are:
http://img.villagephotos.com/p/2009-6/1342104/0
I hope your comments
Thanks in advance.
The hardware used for measurements is:
Targeta Esi juli@ sound.
microphone preamp M-Audio mobile pre usb.
Behringer EMC8000 microphone.
20W amplifier.
Jig, which I built, designed by John K., this is where the link is: http://www.htguide.com/forum/showthread.php4?t=26766&page=1&pp=35
Images of these measurements are:
http://img.villagephotos.com/p/2009-6/1342104/0
I hope your comments
Thanks in advance.
It looks right. I'd say that the data below 500Hz is invalid, as that is likely system or other noise. Usually the bottom end is tailed off to reconstruct the actual (theoretical) low end response.
See here http://www.diyaudio.com/forums/showthread.php?threadid=109574
See here http://www.diyaudio.com/forums/showthread.php?threadid=109574
Using the capacitor to protect the tweeter is fine, as long as the reference point is on the driver side of the cap. But, as you have seen, it consequently degrades the signal-to-noise ratio at the lower frequencies. If you are confident of controlling the signal level to the tweeter you could try it without the cap. But I have no experience testing the limits of what drive levels a tweeter can safely tolerate, so I won't make any recommendations. I recently stopped using a series capacitor for frequency response measurements... but only because I discovered that the tweeter was still undamaged after accidentally testing it without the cap a few times.
BTW, I use SoundEasy.
BTW, I use SoundEasy.
Just by the way:
I find that generally there is a S/N problem at the very low end, because all the equipment in the test chain usually have a roll-off at the low (so it is compounded). At some point I would like to use a DC-coupled amp to improve matters, or at least an amp that starts to roll off at only around 5-10Hz...
I find that generally there is a S/N problem at the very low end, because all the equipment in the test chain usually have a roll-off at the low (so it is compounded). At some point I would like to use a DC-coupled amp to improve matters, or at least an amp that starts to roll off at only around 5-10Hz...
djarchow said:
Right. The problem I have seen, however, is further degradation of S/N towards the lower end due to the roll-off introduced by the cap. This may not be of that much significance. For instance, here widi has captured the most significant part of the tweeter's FR, and the low end can be tailed off. Agreed that with or without the cap nothing will change above 500Hz. The point of my addressing the low end data is that this is his first measurement, and that strange curve is bound to confuse any first-timer.
Well friends, I used another amp, and again I made the measurements, the capacitor is placed on the negative tweeter.
Think that these new measurements.
Here: http://img.villagephotos.com/p/2009-6/1342104/2095188
Think that these new measurements.
Here: http://img.villagephotos.com/p/2009-6/1342104/2095188
I put the capacitor, the output of the sound card.
As the measurements were good, I have adjusted the latency of the sound card in 2048, and the mic preamp to 256.
Here's the results:
http://img.villagephotos.com/p/2009-6/1342104/2095227
As the measurements were good, I have adjusted the latency of the sound card in 2048, and the mic preamp to 256.
Here's the results:
http://img.villagephotos.com/p/2009-6/1342104/2095227
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