Thanks john. This sort of confirms my understanding as well.
Most feeling of compression comes from either the music production end, or some sort of distortion or clipping in the system. In the home listening environment, the temperature does not seem to ever reach levels of significant compression unless playing hard rock of some sort at hear threatening levels for a certain period of time.
Great demonstration.
thermal comression ...
There HAS to be another explanation. I'm skeptic at heart, but I definitely hear ATC 100SL (drivers that most would define as 'pro') as more dynamic and less compressing than VAF i66 (using Seas Excels). That holds even for (very) low level listening, which is very puzzling (at 100dB+ ATCs are in league of their own).
ATCs are more efficient, but not by much, and they use ordinary dome tweeter (probably because SM 75-150s covers up to 3.5kHz). I am an engineer and I would LOVE to understand what is behind this, but so far I can only accept that I can hear it without fully understanding what I am hearing.
PS this is not hearsay, I listen to both speakers on daily basis
There HAS to be another explanation. I'm skeptic at heart, but I definitely hear ATC 100SL (drivers that most would define as 'pro') as more dynamic and less compressing than VAF i66 (using Seas Excels). That holds even for (very) low level listening, which is very puzzling (at 100dB+ ATCs are in league of their own).
ATCs are more efficient, but not by much, and they use ordinary dome tweeter (probably because SM 75-150s covers up to 3.5kHz). I am an engineer and I would LOVE to understand what is behind this, but so far I can only accept that I can hear it without fully understanding what I am hearing.
PS this is not hearsay, I listen to both speakers on daily basis
These two paragraphs seem to be the company line as to why they might subjectively outperform other speakers. But are you using passive ATCs? How do mid band domes do for dynamics vs traditional mid drivers?
"ATC’s magnet design employs a short coil in a long gap with an
undercut center core. This design keeps the voice coil in the portion of the
magnetic field where the lines of force are most uniform. A beneficial side effect
of this geometry is that heat dissipation is improved, maintaining a relatively
constant voice coil temperature, which results in less variation of its electrical and
magnetic characteristics over the full power range of the loudspeaker."
"A third source for distortion has to do with the non-linear magnetic characteristics
of the metal parts the magnet assembly. Current flowing in the driver’s voice coil
induces eddy currents which modify the magnetic field of the carefully designed
magnet assembly. These induced currents tend to buck the voice coil’s magnetic
field, reducing efficiency in a non-linear manner. To minimize this effect, ATC’s
“SL” series bass and low-mid drivers use a new material called Super Linear
Magnetic Material (SLMM) which has the characteristics of high magnetic
permeability and saturation, as well as low electrical conductivity. SLMM
construction suppresses the eddy currents, resulting in a 12-15 dB reduction in
third harmonic distortion."
"ATC’s magnet design employs a short coil in a long gap with an
undercut center core. This design keeps the voice coil in the portion of the
magnetic field where the lines of force are most uniform. A beneficial side effect
of this geometry is that heat dissipation is improved, maintaining a relatively
constant voice coil temperature, which results in less variation of its electrical and
magnetic characteristics over the full power range of the loudspeaker."
"A third source for distortion has to do with the non-linear magnetic characteristics
of the metal parts the magnet assembly. Current flowing in the driver’s voice coil
induces eddy currents which modify the magnetic field of the carefully designed
magnet assembly. These induced currents tend to buck the voice coil’s magnetic
field, reducing efficiency in a non-linear manner. To minimize this effect, ATC’s
“SL” series bass and low-mid drivers use a new material called Super Linear
Magnetic Material (SLMM) which has the characteristics of high magnetic
permeability and saturation, as well as low electrical conductivity. SLMM
construction suppresses the eddy currents, resulting in a 12-15 dB reduction in
third harmonic distortion."
Mostly company **, some truth. The idea of an underhung voice coil is over emphasiszed IMO. It's terribly wasteful of magnetic mass. As I have stated before, I prefer a nice gradual falloff of BL to a sharp change or flat BL. Heat disipation is improved but the coil still changes temperature with power input - nothing can change that.
Flux modulation is an issue, one of the biggest IMO, but a copper or alluminum shorting rings is the best solution. Linear permiability or low electrical conductivity of the pole pieces is not going to work nearly as well as a nice big piece of copper.
Yes, ATCs are passive. And no, I'm not talking about distortion, but purely about subjective sense of dynamics. Seas' are pretty clean in their operational range too, and stay very clean until really pushed (VAFs have two W11s as mids). Yet ATCs always feel at 'more ease' and more 'contrasty' (softer softs and louder peaks, at least subjectively), for the lack of better words. Sorry, I'm hopeless at audiophool-ey descriptions.
Bratislav
Isn't everyone? I mean there are lots of people who spew the terms, but its just as meaningless. Thats why we need good quantitative descriptions, not audiophool ones.
That's very true, but most of us do not have the vocabulary to simply say it plain. Odd as that may seem--the average audiophile doesn't know the professional jargon or the cause and effect of what we are hearing so we make it up. It would be nice if there was an audio dictionary somewhere that wasn't just filled with metaphors. Maybe that should be your next book.
Dan
Hey Dan
The simple realization that the terms being used have no real deffinition and that they were simply "made up", is a quantum leap that most never make. It is far less important to actually know the quantitative terms than it is to accept that the audiophool jargon is on very weak grounds and should not be taken too seriously. Not until there are generally accepted terms that have been shown to be correlated with subjective impressions can one really take the descriptions to have a solid meaning.
I have been using ATC SM75 150S 16 ohm soft domes mids for over 12 years.
Subjectively, they are more dynamic than all cone, dome mids I have heard. (Maybe as a result of their short horn?)
But they do not match the dynamics of a horn loaded mid.
They are cleaner sounding than most horns I have heard.
To me they were a good compromise between the lack of dynamics of cones and the dynamic horn problems.
I've had Altec A5 and Edgars 250hz tractrix horns.
Sticking my head in while the big Edgar horn was playing, I could hear echoes of the music in the horn. (Maybe HOM's?!)
Anyway, my solution was to put felt and wool at the edges to reduce and diffuse edge diffraction. Worked a bit.
I hope to hear a pair of Nathans in the next couple of weeks. If they have the dynamics of horns and more clarity than the ATC's, I'll get a pair.
Nothings perfect.
Good points and well said. Your phrasing reminds me of one of my English professors. He never used an extra word in his writing and if his students did, he'd ruthlessly correct them. Best English class I ever attended. My next English Prof pretty much said the opposite however.😕 I never understood her writing.🙄 Anyway, it always amazed me how much he could say with so few words. He claimed we waste too much of our lives with redundant writing. I wish I had that command of the language as well as a better understanding of how to equate subjective impressions with objective data(quickly back to topic). I think measuring has helped me more than anything.
Dan
Another quantum leap! Your well on your way to actually understanding what is going on. Listening, while undoubtedly the end goal, is not all that useful in the design and development stage. Only near the end when things are almost done. But, if on listening, it is anything but a confirmation of the design and measurements, then you need to go back to the books because there is something that you missed.
Again, I couldn't agree more. This is why I love diyaudio. Experienced and knowledgeable people post here and actually help others. It was a lucky break for me to find this place. For the first 6 months I had litttle clue of what most of these threads were about. I was surprised when a couple months ago someone started a thread saying they didn't like this direction of getting into the scientific rationale for what we should be building. They phrased it differently, but that was their point. 😕 Odd. I just pieced together the best measuring speakers I've had and they just happen to sound better than any of my previous ones (still far from any sort of greatness I'm sure as I've seen your measurements). I know there are even some people seem to believe that if it measures good, it will "invariably" sound bad. That seems so stupid to me it's ridiculous. What the heck are they measuring? Even if I never build a great speaker, the knowledge is priceless.
Thank you again,
Dan
There are a lot of dinosaures in audio.
I find it very odd that I have to rank as one of the senior members (in terms of age and experience) and yet I am one of the most progressive, radical and least attached to the status quo. One generally expects the opposite to be true.
I find it very odd that I have to rank as one of the senior members (in terms of age and experience) and yet I am one of the most progressive, radical and least attached to the status quo. One generally expects the opposite to be true.
That's funny and again true. Whenever I try to spread what I understand to be good speaker design practices elsewhere (measure your designs carefully, control directivity to 90 degrees from their upper limit to under 1kHz if possible, and reduce VERs to the bare minimum), others attempt to debate me. Thankfully it's tough to loose a debate when your argument makes more sense than the opposition's. It stinks that even when others unwittingly contradict themselves within the same thread to support their side, they refuse to concede, get angry, and thus begins the chest beating/mud slinging. I've learned it is more difficult to be humble than proud and designing a good loudspeaker can be humbling. When your design works, then you can be proud.😀
Dan
but,
Dan😉
(from what I've read and my own measurements would lead me to believe)
Dan😉
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I'll through this out there to stir the pot a little. Many speakers that I have auditioned which sound "more dynamic" end up measuring weaker in the low frequency range, below 300 Hz or so. When I say weaker I don't necessarily mean they have a high cut off frequency, but rather that have low Q woofer alignments and/or do not compensate for the baffle step.
This seems to be a very interesting observation. I have also been thinking about such issues. I wonder low Q alignments in combination with large woofer size and high Xmax would be the more dynamic approach.
Thats certainly not been my experince. My system's in-room response ends up being a bit emphasized at the low end (+ about 3 dB at 20 Hz) rather than flat. The reviews all comment about the good dynamics. This contradicts your comment.
I don't think it necessarily contradicts what I said. The question, if directed at your systems would be, what is the woofer alignment and do you correct for the baffle step?
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