I used REW to measure the frequency response of a Heil AMT outside on a 6' ladder, I restricted the sweep to 500-20,000Hz, used 4.6ms gating and no smoothing, the mic was 1M from the driver. Is it supposed to look this lumpy or is this AMT broken? I'm not worried about the rising response just the lumpiness.
this looks good.
Why don't you simply measure it at a distance of 20cm. Then it looks more correct. At 1 meter you measure with room influence.
Why don't you simply measure it at a distance of 20cm. Then it looks more correct. At 1 meter you measure with room influence.
Some other plots - similar to yours, even though they both seem to be using more smoothing.
I assume yours is running dipole, which can cause some inherent periodicity in frequency response.
www.diyaudio.com/community/threads/to-heil-amt-or-not-to-heil-at-140-that-is-the-question.331686/
I assume yours is running dipole, which can cause some inherent periodicity in frequency response.
www.diyaudio.com/community/threads/to-heil-amt-or-not-to-heil-at-140-that-is-the-question.331686/
@ Freecom666: I measured the AMT outdoors with the nearest obstruction being over 30 feet away and the AMT on a 6' tall ladder. I don't think I have an interference problem in the AMT frequency range. But, I'll get a nearfield measurement later today.
@planet10: Thanks for posting those plots. Glad to see my AMT isn't broken, I guess they're lumpy by design.
That's not really lumpy at all if you rescale your graph and it's important to understand why......the diaphram is very light and fast compare to a dome. In real world use and not tone sweeps, that quick response translates to definition and is one of the most extolled virtues of AMTs
Ive done a bunch of ribbon development but no amt experience
If I was to guess, the ugly wiggles in the 3-7khz range may be diffraction effects of the Heils magnet structure
The other possibility is baffle issues.
Are U using a baffle and if so what are the dimensions and where on the baffle do U have the driver?
If I was to guess, the ugly wiggles in the 3-7khz range may be diffraction effects of the Heils magnet structure
The other possibility is baffle issues.
Are U using a baffle and if so what are the dimensions and where on the baffle do U have the driver?