Just an update:
I'll be hearing back from the engineering team on Monday when they return to the office.
I also just received the 6ndl38 drivers and preliminary measurements are showing MUCH more normal behavior. I'll reserve any conclusions until I've burned them in and installed a neoprene seal (B&C drivers ship without these).
I'll be hearing back from the engineering team on Monday when they return to the office.
I also just received the 6ndl38 drivers and preliminary measurements are showing MUCH more normal behavior. I'll reserve any conclusions until I've burned them in and installed a neoprene seal (B&C drivers ship without these).
Still waiting on hearing back from engineering but here's some measurements of the 6ndl38. These measurements have a very similar xover to the 6mbx44 posted earlier. I only adjust the value of the inductor to give it a similar rolloff.
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Imgur: The most awesome images on the Internet
Overall it's more frequency balanced. It's got a little dip at 700 but it doesn't seem to be as severe as the 6md38 posted earlier. I couldn't get it to integrate into my system well (since it was designed around the 6mbx44). The third order distortions are too much for this build so I haven't pursued integrating it fully.
Imgur: The most awesome images on the Internet
Imgur: The most awesome images on the Internet
Overall it's more frequency balanced. It's got a little dip at 700 but it doesn't seem to be as severe as the 6md38 posted earlier. I couldn't get it to integrate into my system well (since it was designed around the 6mbx44). The third order distortions are too much for this build so I haven't pursued integrating it fully.
Hi Spice House,
I can't believe that i missed your post some how so i had to do a search to find this thread.
I like your measurements very much. HD3 is well under the 40dB so well under under 1%. I'm guessing that you mind the HD3 at lower xover frequency point, so you might want to try and make higher order roll-off and that could lower HD3 in that area or just move xover point a bit higher.
I'd try to measure at higher listening level just to see if HD3 will rise or stay low.
What are you using for low and high frequencies ?
I'm glad this fixed midrange problem in your initial setup.
Cheers
I can't believe that i missed your post some how so i had to do a search to find this thread.
I like your measurements very much. HD3 is well under the 40dB so well under under 1%. I'm guessing that you mind the HD3 at lower xover frequency point, so you might want to try and make higher order roll-off and that could lower HD3 in that area or just move xover point a bit higher.
I'd try to measure at higher listening level just to see if HD3 will rise or stay low.
What are you using for low and high frequencies ?
I'm glad this fixed midrange problem in your initial setup.
Cheers
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Hey Zvu,
Unfortunately that level of THD from the 6ndl38 was unacceptable for the concept of this build (very low 3rd order distortion). It was going to require a lot more complicated crossover and use a large cap, so I abandoned it for this build. The 6mbx44 also sounds a lot better
I thought maybe the 6mbx44 I had was defective so I bought a couple more and tested them in the enclosure with the crossover applied.
Imgur: The most awesome images on the Internet
Imgur: The most awesome images on the Internet
Imgur: The most awesome images on the Internet
Imgur: The most awesome images on the Internet
As you can see they were all very similar and consistent, but I could never get them to line up with the factory specs.
Here is one with no crossover in the 3L enclosure. Not exactly what the factory measurement looks like
Imgur: The most awesome images on the Internet
It really is a great sounding driver, so I'm going to tweak the crossover to get it to play as nicely as I can without crossing the tweeter too low.
Still haven't heard back from the manufacturer.
Unfortunately that level of THD from the 6ndl38 was unacceptable for the concept of this build (very low 3rd order distortion). It was going to require a lot more complicated crossover and use a large cap, so I abandoned it for this build. The 6mbx44 also sounds a lot better
I thought maybe the 6mbx44 I had was defective so I bought a couple more and tested them in the enclosure with the crossover applied.
Imgur: The most awesome images on the Internet
Imgur: The most awesome images on the Internet
Imgur: The most awesome images on the Internet
Imgur: The most awesome images on the Internet
As you can see they were all very similar and consistent, but I could never get them to line up with the factory specs.
Here is one with no crossover in the 3L enclosure. Not exactly what the factory measurement looks like
Imgur: The most awesome images on the Internet
It really is a great sounding driver, so I'm going to tweak the crossover to get it to play as nicely as I can without crossing the tweeter too low.
Still haven't heard back from the manufacturer.
Your xover point with the tweeter would be arround 1.8KHz ?
Are you thinking about a notch filter to flatten the frequency response ?
I guess that having midrange with 3 times lower Le is worth it
Cheers
Ya the 6mbx44 really does sound insanely good! Believe it or not that response is already with several notch filters
The crossover freq, depends on how you calculate it, but it should be around there
Hey guys,
Just got an update from the manufacturer. They are going to send me a specially treated 'golden pair' of woofers next month in order to test out the performance. Very excited to measure them!
They also are going to change the manufacturing process in the future in order to compensate for the frequency dip.
Overall, I'm very happy with this response and I'll keep you guys updated.
Just got an update from the manufacturer. They are going to send me a specially treated 'golden pair' of woofers next month in order to test out the performance. Very excited to measure them!
They also are going to change the manufacturing process in the future in order to compensate for the frequency dip.
Overall, I'm very happy with this response and I'll keep you guys updated.
Back to the original question:
"Can anyone help identify what is causing this distortion and phase spike?"
And "There is a dip at approximately 820hz with a distortion spike."
Frequency response dips with distortion peaks in the 700 to 900 Hz range for paper cones woofers are typical caused by bellmouth resonance modes in the cone.
See the link:
http://www.diyaudio.com/forums/multi-way/278348-how-reduce-thd-peak-700hz.html
"Can anyone help identify what is causing this distortion and phase spike?"
And "There is a dip at approximately 820hz with a distortion spike."
Frequency response dips with distortion peaks in the 700 to 900 Hz range for paper cones woofers are typical caused by bellmouth resonance modes in the cone.
See the link:
http://www.diyaudio.com/forums/multi-way/278348-how-reduce-thd-peak-700hz.html
That makes a lot of sense! Hopefully the factory can find a way to dampen this resonance
Yes, with a known resistor and some wires I used REW for the impedance measurements.
Impedance Measurement
Impedance Measurement
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