The distortion peak coincides with the great dip of HF10AK. Could you measure distortion per driver?
Was the group delay chart generated prior to applying a time window to the measurement?
Both drivers measured at 50cm on axis. No EQ, just Xovers.
12P80NDv2
700Hz LR4
HK10AK
200Hz LR4
Cool, it looks like the HF10AK is source for the distortion although here the distortion is quite low +40dB down. On the previous distortion measurement your levels were ~99dB and here ~87dB, according to the legend, and the distortion is was more.
If the distortion doesn't sound bad with usual listening levels then I wouldn't be worried about it. If it sounds bad, honky/grainy/hard/whatever sound that catches the ear occasionally then you could try slide the xo higher up.
On my system/xo variations with HF10AK during past few years I've always gravitated towards higher xo because it sounded better, but it might be due to any reason. I've got smaller of the shelf waveguide, different woofer etc. might be anything. Just an observation that higher xo frequency yield better sound it might we worth a try, especially since you have a DSP. It's been fun observation, I always want to push the xo as low as possible, but end up much higher after a while 😀
edit. just checked current system simulation and seems to be ~20db down around 500Hz, your latest shows around 400Hz. I'm 6db down at 1kHz, so it is a bit higher xo and more gradual slope I think, didn't check what the name of the slope is 🙂
If the distortion doesn't sound bad with usual listening levels then I wouldn't be worried about it. If it sounds bad, honky/grainy/hard/whatever sound that catches the ear occasionally then you could try slide the xo higher up.
On my system/xo variations with HF10AK during past few years I've always gravitated towards higher xo because it sounded better, but it might be due to any reason. I've got smaller of the shelf waveguide, different woofer etc. might be anything. Just an observation that higher xo frequency yield better sound it might we worth a try, especially since you have a DSP. It's been fun observation, I always want to push the xo as low as possible, but end up much higher after a while 😀
edit. just checked current system simulation and seems to be ~20db down around 500Hz, your latest shows around 400Hz. I'm 6db down at 1kHz, so it is a bit higher xo and more gradual slope I think, didn't check what the name of the slope is 🙂
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I've been trying to stay with two test levels
1). 86dB
2). 96dB
So I can compare with some of the speaker reviews over at AS.
I was getting higher than normal distortion on my HF10AKs, I checked diaphragm alignment then tightened bolts carefully while looking at distortion in REW. I found if the balance of torque on the bolts was uneven I would get rising distortion.
That is reasonable thing to do!🙂 However, it is notable how the distortion is roughly 10db worse at the 10db higher output level! Might get into audible territory? Have you compared to the AS reviews, how it compares?
AKC360, nice tip! sensitive devices.
The Genelac 8361A review had a 106dB test too.
https://www.audiosciencereview.com/...s/genelec-8361a-review-powered-monitor.28039/
https://www.audiosciencereview.com/...s/genelec-8361a-review-powered-monitor.28039/
I’ve located the source of the distortion.
The HF10AK adaptor plate was 0.6mm too thick. When bolted up it was not actually sealing well (at all) to the location face at the back of the waveguide.
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Revised HF10AK mounting, Change of rear port stuffing from 20 to 35kg/m3.
Aiming for noise floor below 50dB on the 96dB fundamental chart.
Aiming for noise floor below 50dB on the 96dB fundamental chart.
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There looks to be something odd with the noise floor, it is very spiky in the mid region. It may not affect the result as sine sweeps are effective at rejecting noise but it might be worth trying to track down the cause of.
I may try to measure the cabinet resonances and also pop a 30-PPI plug in the waveguide 🙂
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What's on the other side of the cabinet your mic is on? You will be getting a lot of interferece from the proximity of the mic to any surface. Can you get a cheap mic stand a extend the boom as far out as possible a la:
This is how I do it which is the best I can do in a small british house:
https://www.diyaudio.com/forums/attachment.php?attachmentid=998193&stc=1&d=1637099038
I'd bet the ripples in your noise floor and spectogram are from speaker and mic boundary proximity. Getting the speaker away from walls and up in to the air will help a lot too.
I just bagged a pair of HF10AK so I am reading your thread with great interest. Mine have very minor variation from one unit to the next around the 2k mark. Have you compared yours? Here are mine on STH100 horn at 35cm just for a test run. Distortions:
I hope this helps 🙂
This is how I do it which is the best I can do in a small british house:
https://www.diyaudio.com/forums/attachment.php?attachmentid=998193&stc=1&d=1637099038
I'd bet the ripples in your noise floor and spectogram are from speaker and mic boundary proximity. Getting the speaker away from walls and up in to the air will help a lot too.
I just bagged a pair of HF10AK so I am reading your thread with great interest. Mine have very minor variation from one unit to the next around the 2k mark. Have you compared yours? Here are mine on STH100 horn at 35cm just for a test run. Distortions:
I hope this helps 🙂
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Thanks! I'll have a look at improving methodology.
I tried to match your chart format. This is with minor EQ at 1700 & 2070.
I tried to match your chart format. This is with minor EQ at 1700 & 2070.
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Are you EQ'ing up or down? I tend to EQ everything down rather than EQ one thing up. Choose a low point and aim to level everything down to that to avoid any chance of clipping from the output of the DSP. You can adjust gain afterwards (tho I doubt you will be anywhere near clipping owing to the tiny signal needed to drive these drivers)
PC -> Topping D10s SPDIF -> DC-One -> MC2 T4-250 (CD set +6dB above W)
The DC-One crossover levels are both set to -10dB - no lights are on DC-One outputs at 106dB levels. No lights on the MC2 yet.
I dont use pre-EQ - just use the output PEQs +/- where needed.
A small lesson from the M2.
I’ve installed a high pass 16uF ClarityCap CSA and a 7.8ohm -9dB pad (Jantzen SuperRes).
The horn loading plus a 1070Hz 6dB BW DSP filter creates a 36dB slope with a 700Hz corner.
Added benefit is that a small amount noise / hum has been all but eliminated. These waveguides are a microscope!
Relative distorition plot attached.
I’ve installed a high pass 16uF ClarityCap CSA and a 7.8ohm -9dB pad (Jantzen SuperRes).
The horn loading plus a 1070Hz 6dB BW DSP filter creates a 36dB slope with a 700Hz corner.
Added benefit is that a small amount noise / hum has been all but eliminated. These waveguides are a microscope!
Relative distorition plot attached.
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Updated Limacon v39 to v4.8
https://www.diyaudio.com/community/...-design-the-easy-way-ath4.338806/post-6919819
https://www.diyaudio.com/community/...-design-the-easy-way-ath4.338806/post-6919819