somebodyelse
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Or is accidentally inverted in the GUI
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What am I missing here - Crossover Filters
- Thread starter Robbie010
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Sokel
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About the woofer, lots of pro-drivers recommend a protection HPF at 30Hz or so.
But that's for live performance boxes mostly.
The easiest way would be to put all drivers in a line above each other with a suitable c-c distance. This is what Kimmosto (creator of VituixCAD) says:
Minimum c-c is 1.0 x wave length and maximum about 1.4 x wave length at XO frequency assuming that design is conventional uni-directional box (not open baffle) with phase matching (acoustical 4th order) slopes. Good and quite flexible initial/design value for c-c is 1.2 x wave length at XO, giving smooth combination of power and early reflections i.e. balanced sound without significant power dip at XO due to bump in DI and dip in vertical early reflections. In other words, this concept aims lobe nulls to directions which are the least significant for power response and vertical early reflections - and listener sitting in sweet spot of course.
1/4 wavelength c-c is usually taken as an ideal but it is often difficult to achieve in practice, as the distance between drivers will be so short. In any case with traditional two-way speakers.
Plus if TS possibly pushes in, distance-wise x cm pushes in mainly that Visaton TL 16 H Horn Dome Tweeter so there will be a good time alignment with the other drivers.
- Thread Starter
- #24
Ok, another few hours playing, best advice so far….. check connections, I had one driver connected reverse polarity and two drivers connected to the wrong amps!
Anyway, I ended up here:
Crossovers are 1,200hz and 5,000hz, some light EQ applied.
Anyway, I ended up here:
Crossovers are 1,200hz and 5,000hz, some light EQ applied.
Sokel
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Even if my hybrids are not DIY, I still use control, numbered cables to them.
It's the easiest mistake, anyone messing with multiple amps has probably been there.
Sokel
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And another.
Since you correcting for speaker and not room ( and you can't measure outside using a turntable and the works which you must do at sometime) it might be a good idea to keep your chart at 50dB range, use higher resolution than Psy and tick MTW (multi-time window) under the IR Win tab.
That will give you gated measurements which exclude room for highs or so.
Hello OP @Robbie010,
In your near future optimization procedure and efforts, if possible at your end, I highly recommend you to measure/check Fq-SPL curve(s) in various "stages" of your total signal chain;
1. Line-level or digital-level before going into your DSP unit,
2. Each of the line-level signals after the DSP unit before going into your amplifiers,
3. SP-high-level output from amplifiers before going into SP drivers before protection capacitors,
4. SP-high-level output from amplifiers before going into SP drivers after protection capacitors,
and of course,
5. SP-drivers' actual room air sound (L-only, R-only then L+R) using measurement microphone at your listening position.
These steady and in-order Fq-SPL measurements (L, R, L+R) will effectively indicate/reveal (and hence you can correct/avoid) possible wrong-phase-inversion (at each of the XO/EQ configurations), possible mis-polarity connection into amplifiers and/or into SP drivers.
Please refer to my summary posts #404 and #1,009 on my project thread, for example of such procedures.
As other people pointed, room-mode-tuning and/or SP-physical-alignment-tuning should be done after these fundamental measurements for further optimization of your actual room sound to be heard at your listening position. Of course, you would need further spiral of DSP tuning, room-mode tuning and SP-alignment tuning; yes, it will be long audio exploration journey.
In your near future optimization procedure and efforts, if possible at your end, I highly recommend you to measure/check Fq-SPL curve(s) in various "stages" of your total signal chain;
1. Line-level or digital-level before going into your DSP unit,
2. Each of the line-level signals after the DSP unit before going into your amplifiers,
3. SP-high-level output from amplifiers before going into SP drivers before protection capacitors,
4. SP-high-level output from amplifiers before going into SP drivers after protection capacitors,
and of course,
5. SP-drivers' actual room air sound (L-only, R-only then L+R) using measurement microphone at your listening position.
These steady and in-order Fq-SPL measurements (L, R, L+R) will effectively indicate/reveal (and hence you can correct/avoid) possible wrong-phase-inversion (at each of the XO/EQ configurations), possible mis-polarity connection into amplifiers and/or into SP drivers.
Please refer to my summary posts #404 and #1,009 on my project thread, for example of such procedures.
As other people pointed, room-mode-tuning and/or SP-physical-alignment-tuning should be done after these fundamental measurements for further optimization of your actual room sound to be heard at your listening position. Of course, you would need further spiral of DSP tuning, room-mode tuning and SP-alignment tuning; yes, it will be long audio exploration journey.
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- Thread Starter
- #28
Thanks all. I'm sure its going to be a long journey, I'm just getting to grips with the basics of REW sweeps so I've a big learning curve ahead.
@Sokel - I can see what you mean about the scaling and mtw, its looks awful now....
. I know the dip between 30-60hz is a room mode then there is the big dip at the 1.2khz crossover point.
One thing I would like to understand is the way in which I should test / evaluate the speakers i.e. the process that should be followed.
For instance, is it best to play around with x-overs / gain and measure each driver individually in order to workout their optimum performance and then test each individual speaker as a whole and then the pair combined?
What I found yesterday was that while testing, measuring and playing around with a single speaker in order to dial in basic crossover and gain settings, the result of that testing completely changed once I switched to testing the speakers combined.
Ultimately, I'm not trying to produce a commercial product, I'm trying make a bespoke setup that works for me, in my room and more particularly, at my seating position. However, given that I have the option produce multiple profiles, I would like to be able to switch between profiles depending on my want / need such as, a profile that is optimised for on axis listening at my seating position, a profile that is optimised for off axis listening at a different seating position etc.
@Sokel - I can see what you mean about the scaling and mtw, its looks awful now....
. I know the dip between 30-60hz is a room mode then there is the big dip at the 1.2khz crossover point.One thing I would like to understand is the way in which I should test / evaluate the speakers i.e. the process that should be followed.
For instance, is it best to play around with x-overs / gain and measure each driver individually in order to workout their optimum performance and then test each individual speaker as a whole and then the pair combined?
What I found yesterday was that while testing, measuring and playing around with a single speaker in order to dial in basic crossover and gain settings, the result of that testing completely changed once I switched to testing the speakers combined.
Ultimately, I'm not trying to produce a commercial product, I'm trying make a bespoke setup that works for me, in my room and more particularly, at my seating position. However, given that I have the option produce multiple profiles, I would like to be able to switch between profiles depending on my want / need such as, a profile that is optimised for on axis listening at my seating position, a profile that is optimised for off axis listening at a different seating position etc.
Sokel
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I have to warn you, this will be steep.Thanks all. I'm sure its going to be a long journey, I'm just getting to grips with the basics of REW sweeps so I've a big learning curve ahead.
@Sokel - I can see what you mean about the scaling and mtw, its looks awful now....
View attachment 478825
One thing I would like to understand is the way in which I should test / evaluate the speakers i.e. the process that should be followed.
For instance, is it best to play around with x-overs / gain and measure each driver individually in order to workout their optimum performance and then test each individual speaker as a whole and then the pair combined?
What I found yesterday was that while testing, measuring and playing around with a single speaker in order to dial in basic crossover and gain settings, the result of that testing completely changed once I switched to testing the speakers combined.
Ultimately, I'm not trying to produce a commercial product, I'm trying make a bespoke setup that works for me, in my room and more particularly, at my seating position. However, given that I have the option produce multiple profiles, I would like to be able to switch between profiles depending on my want / need such as, a profile that is optimised for on axis listening at my seating position, a profile that is optimised for off axis listening at a different seating position etc.
But it will be a great learning experience and will save you tons of trouble when you get the basics:
VituixCad is just about the best tool on the planet for anyone messing with speakers.
Keith_W
Master Contributor
The first thing you need to do is to check that all your drivers sum properly. Do this:
- You need to take a free-field measurement of each individual driver with the crossover in place. "Free-field" means NO ROOM REFLECTIONS. This may be possible in-room if your room is large, but you are likely to get more success if you take your speakers outside and elevate them. Place your mic about 1m on-axis to each driver and sweep it.
- Once your measurement is taken, check the quality of each measurement by looking at the ETC (for reflections) and waterfall (for signal-noise ratio). Read this thread for some pointers.
- To check that it sums, use REW "Trace Arithmetic A+B".
It is possible that the drivers will not sum to flat. Since you have DSP, your options are:
- try to time / phase align each driver
- if the discrepancy is large, consider inverting the polarity of one driver
- you can try to design an all-pass filter to straighten out the phase a bit at the summation point
There is too much to cover in a forum post. You need to buy this book and read the section about crossovers.
- You need to take a free-field measurement of each individual driver with the crossover in place. "Free-field" means NO ROOM REFLECTIONS. This may be possible in-room if your room is large, but you are likely to get more success if you take your speakers outside and elevate them. Place your mic about 1m on-axis to each driver and sweep it.
- Once your measurement is taken, check the quality of each measurement by looking at the ETC (for reflections) and waterfall (for signal-noise ratio). Read this thread for some pointers.
- To check that it sums, use REW "Trace Arithmetic A+B".
It is possible that the drivers will not sum to flat. Since you have DSP, your options are:
- try to time / phase align each driver
- if the discrepancy is large, consider inverting the polarity of one driver
- you can try to design an all-pass filter to straighten out the phase a bit at the summation point
There is too much to cover in a forum post. You need to buy this book and read the section about crossovers.
I use color-coded multi-core (4-core AWG10, 8-core AWG12) Vinyl Cabtyre (VCT) cable for SP-cables in my PC-DSP-based multichannel multi-amplifier multi-SP-driver fully active audio setup.
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Yes, I fully agree!
Just for OP @Robbie010's possible reference and interest, I have/had these posts on my project thread:
- Useful public domain documents and books for understandings on audio crossover: #132-#135
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