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Posts by cjwhitehouse

You should not assume that this response is representative of production 1812's. When we tested one at AV:Talk, we were sent a new version of firmware to load (v2.1, I think). Prior to this version, I believe the 1812 had its own dedicated firmware. Bruce just told us to load the new version into both 1812 and DD-15 prior to testing, which we duly did on site and then ran the tests with the results as presented. It later transpired that Velodyne hadn't fully tested this...
As the perception of extreme LF tends towards sensing the individual pressure changes, the ear also tends to respond to the peaks more than the RMS level, lowering the threshold of hearing by 3-4dB. This effect also crops up in masking where two sine waves are within, say, 10Hz of each other, the ear detects the beats between them, lowering the threshold at which the quieter signal can be heard. Eliminating the beats is one reason for using narrowband noise rather then...
I'm not sure I agree with this. For me a masking test has to involve two distinctly different signals, say, two different sine wave frequencies, or noises of different bandwidths or a combination of the two. If you simply use two sine waves of the same frequency, or two noise signals based on pink noise, even if one is limited in bandwidth, and add them together, what you are really discussing is a "loudness perception" test. And it is pretty well understood that the human...
It's most of the bass and mid-range that has gone in the left ear. What I am left with is really tinny and buzzy sounding. I cannot understand speech from a mobile phone held to that ear at all. And the accompanying tinnitus alters the timbre of everything I hear when using both ears. Organ and choral music is torture to listen to as it becomes an unintelligible wall of noise at any decent volume. I've had all the PET and MRI scans looking for the usual suspects and so far...
I'm not sure the old grey matter quite follows what you are proposing to do. If you distort each note separately, then the result will not be entirely realistic as no IMD will be created between the different notes of chords. Are you proposing different profiles of distortion in terms of the orders present for different frequency bands or just varying the relative amplitudes? Would be interested in how your "variable HD distortion by frequency" program works and why it...
Not quite true. Polk Audio, who were involved in the original development of the CEA2010 standard, do publish "Loud and Low" numbers for all their latest subwoofer models measured according to CEA2010. But unless this is adopted more widely by the industry, it becomes a rather pointless exercise for Polk to continue doing this.
http://projekter.aau.dk/projekter/fb...s_07gr1062.pdf Some interesting data in there if a little hard to digest. Some of their assumptions seem a little questionable and their conclusion:"The results indicate that approximated expressions describing the ERB changes with frequency, although useful in other frequency ranges, fail to describe what has been obtained in the range 31.5-125 Hz. Deviations are found in general, the average ERB at 31.5 Hz (17 Hz) being...
If you insist on 100% accuracy and happen to have access to a working copy of the Klippel model and a suitable set of typical state variables, I would be happy to use it here. But in the absence of that we are left with trying to do a 90% job using relatively simple tools that are available. Can a test based on single tones (or shaped tonebursts) fully assess the large signal behaviour of a subwoofer? Clearly not, as it fails to excite all relevant non-linear behaviour. As...
Very possibly, though I tend to be fairly selective on where I post these days. My chief claim to fame is being behind the AVTalk subwoofer tests but I haven't had time to do any in the last 12 months due to other commitments.
Depending on how good your maths is, have a read of Keith Howard's article here which explains how AddDistortion works and its limitations. I have spent an altogether unhealthy amount of time investigating distortion measurement in my spare time so I thought I would share the benefits of any insight that I have gained along the way. The Aalborg University thesis paper you linked to earlier is a good read and replicating some of that work has been quite...
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