Re-arranged the furniture a little and got the equipment set up.
Sure as was suggested, I had a broad dip just above 2K. This is above the crossover and much broader than the typical crossover dip. The brightness of the room is still a bit of a problem, but just the "tone" control JDS Labs midrange boost helped quite a bit. Now to get more serious with the APO eq. Also have a hump around 500 that would also be the room as I did not have it in Maryland. Not sure where that is coming from.
Using HOLM. MLS.
The DXT tweeter may still have some positive attributes. Basically the same driver as I have, but in the waveguide and recessed about an inch. With a small nicely rounded ring under the woofer, I could better time alignment.
Sure as was suggested, I had a broad dip just above 2K. This is above the crossover and much broader than the typical crossover dip. The brightness of the room is still a bit of a problem, but just the "tone" control JDS Labs midrange boost helped quite a bit. Now to get more serious with the APO eq. Also have a hump around 500 that would also be the room as I did not have it in Maryland. Not sure where that is coming from.
Using HOLM. MLS.
The DXT tweeter may still have some positive attributes. Basically the same driver as I have, but in the waveguide and recessed about an inch. With a small nicely rounded ring under the woofer, I could better time alignment.
Phase and frequency response are linked and the droop is likely due to phase difference of the drivers, as you state.
Here is quick GIF demo attached, ideal drivers with ideal 4th order LR xo at 2kHz. Shifting acoustic center of the tweeter just some 3cm towards the listener cause phase misalignment which creates wide droop ~above xo.
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My droop was wider than that. I am also still hot between 3 and 6K. Quick fix is just some eq, but I will need to pull the drivers out and make new FRD and ZMA files before I fix it properly. Moving to the DXT tweeter may make it a lot better as the offset is then less than a cm. I have an old Old Colony "Pulser" I can use to get very accurate AC delta measures.
I picked an in-room listening position target of a -5dB slope from 2K to 20K. I will go through a variety of recordings to see how that fits. First impression is it is still on the bright side. Next step is to pipe my HOLM signal into the PC so it can pass through the APO eq to verify my spreadsheet calculations. I am analog from the Focusrite into the DAC right now.
With accurate .zma and .frd files, you can use PSD Lite and make decent compromises between response and phase coherency. Handy tool but has filter complexity limitations and only gives you on-center estimates.
Ideal drivers would be nice, but I live in NC and Ideal is in Ga. 🙂
I picked an in-room listening position target of a -5dB slope from 2K to 20K. I will go through a variety of recordings to see how that fits. First impression is it is still on the bright side. Next step is to pipe my HOLM signal into the PC so it can pass through the APO eq to verify my spreadsheet calculations. I am analog from the Focusrite into the DAC right now.
With accurate .zma and .frd files, you can use PSD Lite and make decent compromises between response and phase coherency. Handy tool but has filter complexity limitations and only gives you on-center estimates.
Ideal drivers would be nice, but I live in NC and Ideal is in Ga. 🙂
I think I have seen that mentioned. A side detriment is it moves the tweeter further away from the woofer. I am one of those people who cut an arc out of the tweeter to get it an inch closer. At least on the cheaper plastic ones. Somewhat interested in the new small form factor tweeters from SS and Seas. I guess for cars, but if they work, then they work.
I also did some chirps with TrueRTA. Shows the same basic mid range dip, but highlighted a 500 Hz hump. I guess time to load up a signal generator and try to find the cause. I have had a window balance spring resonate, back of a china cabinet, recessed bookcase, and a center channel all excite or absorb selectively in previous houses. Who knows what it may be this time. Wavelength may lead me to the fireplace.
I also did some chirps with TrueRTA. Shows the same basic mid range dip, but highlighted a 500 Hz hump. I guess time to load up a signal generator and try to find the cause. I have had a window balance spring resonate, back of a china cabinet, recessed bookcase, and a center channel all excite or absorb selectively in previous houses. Who knows what it may be this time. Wavelength may lead me to the fireplace.
It's said that achieving good phase/time alignment w/2nd order LR filter is difficult, especially on a flat baffle without making a ladder delay circuit. Have you tried this?
Nope but have realized that. On the other hand, I tend away from higher order electricals. 3rd max for passive. A ladder really gets the parts count up there. Kind of a band-aid I think but have not built one to listen. I am leaning to swapping to a DXT so I get closer to acoustic center alignment without new boxes. I was only able to get to about 15 degrees across crossover with an acceptable response. Simulation says I can do better with offset.
My quandary is that I kind of would like to try the Satori ring as it may be all around a better tweeter, but that means totally new build even if I keep my woofers. I got the room a little better. Looking into the curtain liner idea and I have to track down a couple resonances. I should be able to get it good enough for my hearing, as I don't hear as well as I did 50 years ago. A little less up top and a little higher background noise. The DXT may be good enough if executed well enough.
My quandary is that I kind of would like to try the Satori ring as it may be all around a better tweeter, but that means totally new build even if I keep my woofers. I got the room a little better. Looking into the curtain liner idea and I have to track down a couple resonances. I should be able to get it good enough for my hearing, as I don't hear as well as I did 50 years ago. A little less up top and a little higher background noise. The DXT may be good enough if executed well enough.
Rather than going to these lengths, try adjusting the filters to produce the wanted phase interaction.
I could not get exact matching through crossover. When it was on, the response was off too much. Now it could be the best solution is to get the phase correct and then add DSP eq. as it is then not fighting phase.
I have the same experiences, when phase alignment is off it's causing issues with depth of the sound stage.
Maybe try adding a woofer 'spacer'/stepped baffle to time align the drivers, or try the DXT tweeter (might even fit without modification to the baffle?), then remeasure and redesign the XO.
Maybe try adding a woofer 'spacer'/stepped baffle to time align the drivers, or try the DXT tweeter (might even fit without modification to the baffle?), then remeasure and redesign the XO.
Can you attribute an effect to it? Offsetting phase isn't wrong if you do it for the right reason.
I'll sometimes find that phase is hard to control when the measurements are off.
I'll sometimes find that phase is hard to control when the measurements are off.
You could learn from the ER-DXT design. Mark K chose 2nd order acoustic slopes for a good reason, in order to acquire a good directivity pattern around X-over. That kind of design aspects really is much more important than picking the one or other expensive tweeter. Generally, with a wellfit execution, you won't notice the difference between two good tweeters.
Agree, proper execution beats expensive drivers, to a point of course where better drivers properly executed will win.
My experience has shown me that, to my ears, phase alignment of crossovers in the 1.5k to 2.5k region by itself is not audible.
I base this statement on careful listening comparisons of an LR4 crossover at 1.6k to a 3rd order crossover at 1.8k. The 3rd order crossover has a phase difference of about 90 degrees, while the LR4 has a phase difference of about 0 degrees.
The on-axis system response of both crossovers was matched to +/- 0.5 dB.
I have tried to hear differences, but I just do not hear much difference. When I do, I sometimes prefer the phase-matched LR4, and sometimes I prefer the 90 degree phase 3rd order.
So for me, in my room, with my ears, I don't think I can detect a phase difference between the mid and the tweeter, as long as everything else is working properly from a frequency response standpoint.
j.
I guess the effect depends on the listeners ear, but to me good phase tracking around XO frequency sounds better in the depth of the soundstage. Bad phase tracking sound more flat to me. I think it can even sound more 'smooth', and I imagine it's because transients are not aligned as well.
It seems time aligning the drivers make XO work easier (and cheaper), and maybe in some cases impedance is easier for the amp too, like for example 'twisting' the phase of the tweeter with a low inductance coil etc.
I have even done some experiment with DSP to time align woofer with mid (around 300Hz), and thought it sounded better (especially bass guitar). It is not something I have done physically using passive XO though, since it would look a bit odd with the woofer sticking out 5-10cm.. I only aimed for as good as possible tracking between bass and mid with passive XO.
General opinion seems to be that phase tracking not matter at lower frequencies, but I would beg to differ, even if the effect is not as obvious as mid to tweeter.
Not sure what you mean by that? Bad measurements?
If you're thinking of adding in DSP, then just use an electronic delay to fine tune it.
Yes, there will be differences to be mindful of and manage, and they'll interact differently with the room in the bigger picture.
I read a study recently that put delay detection in participants around +/-0.5ms ... saw some other study that put audibility in (us) territory. The latter was quite a surprise to me. Seems that people are more sensitive to phase alignment than was previously thought.