Tim, actually I haven't tested that. Speakers are 2' from wall but rotated 30deg so on-axes cross a bit In front of the "spot". All my room response measurements are with that placement. Other measurements with the speaker dragged in the middle 2m from walls (mor).
I can run some sweeps tonight and publish them in my thread for discussion!
I can run some sweeps tonight and publish them in my thread for discussion!
Last edited:
Musing again, I think it would be very interesting to insert into the signal chain a parallel network of a diode and a pot, so that at maximum the diode is 'not there', but as it is rotated, the signal becomes increasingly asymmetrical.
From this we can detect thresholds of sensitivity of asymmetrical sine waveforms.
From this we can detect thresholds of sensitivity of asymmetrical sine waveforms.
That may be so, but in this situation the back EMF is assisting the cone in one direction and impeding it in the other, this is not just a pure resonance, but one under the influence of a one way current from the low frequency, continuing through both halves of the cycle of an upper frequency; it assists in one direction and impedes in the other.
Looks like the same exact type of foam pyramids I use. Regardless of enclosure shape; we still need to get the overall combined "Q" to OUR "personal" liking. We still need to absorb and dampen as much unwanted energy FROM EVERY SOURCE as much as possible also.
These days, I tend to prefer an overall "Q" less than 0.707. I mostly listen to classical; full symphony orchestra as well as Baroque and other era chamber music. I also listen to a lot of mostly acoustic based jazz. I do still rock out from time to time but prefer quick and precise transients to a lower in room f3, f6, f10, etc. [all else being equal!!!]. I have many drivers; each pair with it's own amplifier so I can adjust gain accordingly without needing any "bass enhancement" from a box with a higher Q. (This IS taking into account room modes and room gain)...
These days, I tend to prefer an overall "Q" less than 0.707. I mostly listen to classical; full symphony orchestra as well as Baroque and other era chamber music. I also listen to a lot of mostly acoustic based jazz. I do still rock out from time to time but prefer quick and precise transients to a lower in room f3, f6, f10, etc. [all else being equal!!!]. I have many drivers; each pair with it's own amplifier so I can adjust gain accordingly without needing any "bass enhancement" from a box with a higher Q. (This IS taking into account room modes and room gain)...
I read through this thread rather quickly but don't think this has been put forward as a suggestion. I.e. using more than one drive unit such as MTM. For a given midwoofer design, an extra midwoofer would give 6dB gain which would mean for a given spl level the cone would only need to move by 1/4 of the displacement. For a given internal box design with chosen stuffing or absorbent solution as mentioned previously, having two such boxes dealing with less energy into each box would help, would it not?
I know MTM vs 2 way has its own debate but that aside....
I know MTM vs 2 way has its own debate but that aside....
The backEMF is AC and works both ways. So does ringing. One part of what you seem to be describing is a phase difference between voltage and current, which isn't in itself asymmetrical.
The other part, if I understand you, would be the asymmetry of the envelope of the waveform, which is a different thing.
Your maths is out.
If you double the cones, each must move half the amount, so that the same volume of air is being shifted.
With regards to the rest of it, you'd also double the radiating area of the cabinet, so any sound passing through the cabinet walls will also increase in level. Similarly, any sound bouncing around inside the cabinet and exiting via the cone will also increase.
No net gain or loss, I'm afraid.
I do think I covered the unwanted cabinet sound portion of this quite comprehensively in an earlier post: https://www.diyaudio.com/forums/multi-way/360015-box-sound-7.html#post6338825
Chris
I asked for references but nothing forthcoming as yet. Is this an interesting theory or conjecture?
Thanks, I'd like to know more, how and why this is the case. Nelson says:
"Simplicity is not the only reason for the use of the single-ended topology. The characteristic of a single-ended gain stage is the most musically natural. Its asymmetry is similar to the compression / rarefaction characteristic of air, where for a given displacement slightly higher pressure is observed on a positive (compression) than on a negative (rarefaction). Air itself is observed to be a single-ended medium, where the pressure can become very high, but never go below 0. The harmonic distortion of such a medium is second harmonic, the least offensive variety."
Which is probably what X is paraphrasing.
"Simplicity is not the only reason for the use of the single-ended topology. The characteristic of a single-ended gain stage is the most musically natural. Its asymmetry is similar to the compression / rarefaction characteristic of air, where for a given displacement slightly higher pressure is observed on a positive (compression) than on a negative (rarefaction). Air itself is observed to be a single-ended medium, where the pressure can become very high, but never go below 0. The harmonic distortion of such a medium is second harmonic, the least offensive variety."
Which is probably what X is paraphrasing.
Which bit? As far as I know hearing sound that travels through air is the usual natural way to hear it.
Also I can't find where Boyle mentions asymmetry
Last edited:
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.