Yes, that is what i was thinking he meant, too.
Hoping he meant that really, because i believe that is an intuitive leap in understanding the relationship between the time domain (impulse / energy-time-curve response) and where on the frequency & phase traces the time domain spectral energy comes from.
Thanks for those links David.
2nd Bench Brief paper was certainly more digestible than the first.
but i did see things in the first one i could wade through...and particularly liked the opening pages describing GD's two basic parts...constant and variable..
I have a question that is unrelated to group delay and I don't want to break the momentum there (causes the internet needs it lol) BUT I need to understand something before I can begin certain aspects of my build...
So when I take a measurement at the mouth of the horn, it is not the same measurement as 1 meter....the slope of the FR has changed and the where the HF might be down 20db at 20khz, if measured from 1 meter the FR is much closer to neutral.....WTF is that!? What part of sound physics did I miss?
I think this has something to do with the amount of direct energy?
So when I take a measurement at the mouth of the horn, it is not the same measurement as 1 meter....the slope of the FR has changed and the where the HF might be down 20db at 20khz, if measured from 1 meter the FR is much closer to neutral.....WTF is that!? What part of sound physics did I miss?
I think this has something to do with the amount of direct energy?
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Holger may have had tube amps in mind when he made that comment.
While most professional midwoofers and some subwoofer drivers are fine for hi-fi use, only a few work well with low-power SET amplifiers.
I've simmed the 15NLW9300 in a medium sized and big BR cab and I'm afraid it's still a heavy load for most SET amps, despite the above average η₀ and the supposed tube-friendly impedance.
Low Qts / high BL usually requires beefier amps. Unison Research own tube amps are powerhouses compared to a 2A3 SET or similar.
With the mic directly at the mouth you're actually measuring the direct response of the driver + horn system, including the phase induced anomalies caused by internal reflections etc.
You need to measure at some distance of the horn mouth (the acoustic source) so that the response settles out.
Herein a driver + horn is clearly different from a direct radiator > the acoustic impedance matching between the diaphragm and free air.
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https://www.dj-store.ru/data/files/files/1094_file.pdf
What do you guys think of this for a top? Vs Axi + Horn, pros n cons?
What do you guys think of this for a top? Vs Axi + Horn, pros n cons?
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The VX 15HP polar response looks smooth from around 1kHz to near 10kHz, both horizontally and vertically, good for near and far field response on/off axis.
Without seeing the polar response of an Axi + Horn + 15", not much to compare, other than the larger Sd of the Axi's diaphragm should allow more output potential above 1.3kHz than the VX 15HP.
Without seeing the polar response of an Axi + Horn + 15", not much to compare, other than the larger Sd of the Axi's diaphragm should allow more output potential above 1.3kHz than the VX 15HP.
That's what I would expect as well.
The only Tannoy 15" Pro driver I know is the older Tannoy 3816 that was used in the V15 and which looks different from the driver in the more recent VX15 HP.
Attachments
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Attached are a few datasheets of 15" Audax woofers including Spectral Decay and Step Response plots.
Here's a discussion on the topic and here are some measurements in a treated room.
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It's made by Fane, like many drivers of UK loudspeaker manufacturers.
Quote from Electronic Music Maker, August 1981:
"Fane Acoustics, who have been making loudspeakers for the home hi-fi and television industries since their establishment in 1958 by Dennis Newbold and Arthur Falkus. Leading hi-fi manufacturers at the time, such as Daystrom, Tannoy and B & W, used Fane's early 12 inch diameter hi-fi loudspeakers and gradually the range was increased to cover 8, 10, 13 x 8, 15 and 18 inch models as well."
Funktion One also uses Fane drivers in their smaller horn tops.
