I assumed that various distortion that is taking place due to LF excursion causes simultaneous higher frequency oscillations to be subject to the same conditions that causes the LF to distort. I will say this, Taking high level Horn measurements is taxing enough. Using the method of measuring THD of the voiced driver without horn, is more intimate, and the spl levels are significantly reduced while keeping voltage the same.
Every time I see this thread under New Posts, it gives me a big laugh! Carry on!
As I experiment with possible configurations, I am coming to the conclusion that Damping material, is better than shorter slot, which makes damping not an effective option (top pic) and a tringle shaped "phase plug" (2nd pic), what's the purpose if not better than the dampened original slot.
I guess I have to accept that damping out the resonance is the best option. Also happens to require the least reconstruction.... I just dont see how to beautify it all =(
Also 😂
I guess I have to accept that damping out the resonance is the best option. Also happens to require the least reconstruction.... I just dont see how to beautify it all =(
Also 😂
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Many would have paid no attention to an off topic post, but it's kind of hard to ignore now..
@Allen I need to control myself. For sure, a new pet peeve has been unlocked;
Microaggression is a term used for commonplace verbal, behavioral or environmental slights, whether intentional or unintentional, that communicate hostile, derogatory, or negative attitudes toward those of different races, cultures, beliefs, or genders.
I've done good work.
I think I know how to incorporate the 3rd set of 18's..... my Original issue was that one of the 18's is in 4ohms (tricky salesmen or bad customer, ur call)... Supposedly I can wire in a resistor to get it play at 8ohms. My studies are suggesting that this will change the damping from the amplifier>? How much could performance change?
Microaggression is a term used for commonplace verbal, behavioral or environmental slights, whether intentional or unintentional, that communicate hostile, derogatory, or negative attitudes toward those of different races, cultures, beliefs, or genders.
I've done good work.
I think I know how to incorporate the 3rd set of 18's..... my Original issue was that one of the 18's is in 4ohms (tricky salesmen or bad customer, ur call)... Supposedly I can wire in a resistor to get it play at 8ohms. My studies are suggesting that this will change the damping from the amplifier>? How much could performance change?
The four ohm woofer is still four ohms, the series resistor turns all the power it receives into heat.
If you use reasonable size speaker cable, the tiny change in damping factor at the speaker won't be an audible issue.
Without a series resistor you might see as much as a +3dB difference in frequency response, depending on how well matched the 4 ohm vs 8ohm drivers are.
With a series resistor, you might get performance closer than that.
Another measure and listen opportunity.
Adding another two speakers to the four will gain at most 3.52 dB if your amp is a perfect voltage source, and they are incorporated with no cancellation, not likely.
Considering your current angst regarding amplitude modulation distortion ("parasitic non linearity" as you dubbed it..) it would make more sense to use your 15" drivers for midrange to reduce that potential problem in the response of the 18" and HF driver, while eliminating the frequency response problems inherent in your current set up you have been writing about correcting for months.
Cheers,
Art
Just measure both curves and overlay them you may be surprised. Besides the shift of spl, the series resistor should bump the LF as sfik the series resistor influences the Qts of the driver.
@mark100 I know you have plenty of DSP experience, Am I mistaken in thinking I will be able to flatten the phase of my Slot loaded woofers?
This outdoor measurement for example?
Or This one which represents a worse case scenario indoors
Fix Fr and you fix phase they said. Well thats not true in every case, apparently
Phase effects summing, demonstrated below
I am wondering how well can DSP deal with these phase issues and what are the consequences? Unlike changing Group Delay, I hope to not add any significant delay to the signal. If anyone has any clarity on this topic, I'd appreciate it.
I see kids putting coins and broken crayons in those slots. They disappear like ... magic!
Pretty much every horn, point source driver I've worked with required some amount of damping and historically some sort of protective/decorative grill has been the tried n' true way.
@GM I do remember you speaking of using loudspeakers that over over-dampened in order to compensate for the room? I was going to ask you about this anyway so, here we are. Q seems to be achieved with eq so whats the matter if the enclosure needs eq's help getting there not?
Also how exactly do I approach this with the grill? Better yet, how does one critically damp using a slot like above?
Also how exactly do I approach this with the grill? Better yet, how does one critically damp using a slot like above?
@mark100 I know you have plenty of DSP experience, Am I mistaken in thinking I will be able to flatten the phase of my Slot loaded woofers?
This outdoor measurement for example?
Or This one which represents a worse case scenario indoors
Your outdoor measurement would flatten fairly easily using FIR.
Although the majority opinion is that doing so is not a good idea, as that creates a pre-ring possibility with no complementary xover offset since it is a system high-pass. Step response will show a major dive below 0, before impulse peak.
I share the view it's most likely a bad idea, certainly so if the FIR file used to do it is a global file on top of whole speaker.
However, if the FIR file and linearization are just for the sub channel, I'm still uncertain about much phase linearization can be done for the benefit of reducing phase rotation/group delay, at the expense of 'potentially audible' pre-ring.
Dunno, right now on bass-reflex, i Ieave phase from the natural mag rolloff alone, and just linearize the electrical high-pass. Seems to be a good compromise.
The indoor? I set up the sub via outdoor meas. Never touch that processing again. Once indoors, I usse a separate layer of processing for the room integration. I don't trust sub measurements indoors. 9 times out of 10 at LP, reflections are stronger than direct, dominating FFT analysis.
I can't make sense of what you mean. Where's the example of fixed FR? Fixed means flat.
(Btw, Magnitude is better term than FR, because FR should mean both mag and phase)
@Ro808 That would be the basis of it yes....I have 4 18h+ and 4 Oberton 15NMB600 to play with. So far the only trouble I have had with the room is a null at about 40hz, which is from the corner itself I believe. This was measured with only the lower box in the corner. I think with the horn in the way and finally with another box above the horn, it could break up that issue. So corner loading and keeping all sources collocated has been the idea. Multi sub placed independently doesn't seem to make sense just yet... Not sure why I'd want bass to come from behind me when I get great FR from the corner placed speakers which is, expected.
If I can pull it off.... my PPMSL idea will be sufficient. I'd use the 15"s and the 18's below. 3 amps will be needed but whats a guy to do. @Ro808 while I wait for @mark100, maybe you know about the potential of DSP to fix phase? The post above talks about the issues of phase and PPSL. If its a tame-able issue then I have no reason to move forward.
I did think about using the 15's in the front MTM style with the two 18's facing the rear. Thats really not a bad idea either. I would slot them like in the picture below, maintaining the same look.
I am concerned with reaching my efficiency goals. Keeping the woofers grouped together in PPSL is the most efficient I think. I'f I did 2 15's and 2 18"s in back, I might have to high pass the 15"s to keep my <2mm excursion goals, and I kinda didn't want to have to do that. I could likely low pass the rear 18"s at 120hz but the increase in efficiency is still less than ppsl configurated. Also a potential issue is FR off axis on the vertical axis for slots. I can;t say I understand their behavior 100%
If I can pull it off.... my PPMSL idea will be sufficient. I'd use the 15"s and the 18's below. 3 amps will be needed but whats a guy to do. @Ro808 while I wait for @mark100, maybe you know about the potential of DSP to fix phase? The post above talks about the issues of phase and PPSL. If its a tame-able issue then I have no reason to move forward.
I did think about using the 15's in the front MTM style with the two 18's facing the rear. Thats really not a bad idea either. I would slot them like in the picture below, maintaining the same look.
I am concerned with reaching my efficiency goals. Keeping the woofers grouped together in PPSL is the most efficient I think. I'f I did 2 15's and 2 18"s in back, I might have to high pass the 15"s to keep my <2mm excursion goals, and I kinda didn't want to have to do that. I could likely low pass the rear 18"s at 120hz but the increase in efficiency is still less than ppsl configurated. Also a potential issue is FR off axis on the vertical axis for slots. I can;t say I understand their behavior 100%
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TMT vs TM
vs
I am starting to be under the impression that the MTM is actually the choice speaker for the purest/critical listener. I do not think that a typical crossover point of TM will be able to give a better image than an MTM would. The way I see it, a TM allows better dispersion above the Tweeter axis, this is something critical listener doesn't care about. MTM asks the listener to remain on axis to avoid the null created by the top or bottom woofer. This is something a critical listener doesn't care about. I should have pointed out this rant is geared towards large builds using large woofers and waveguides. With that in mind I am not convinced that a TM is able to give a point source like presentation in particular in vocals, in particular, the closer one chooses to sit. @IamJF Chose to get rid of his extra mid, but I would claim that the CTC is no where near that of a 15"+ large Waveguide.
I think what has me leaning towards the potential of MTM is listening to stereo monitors, period. When working at least somewhat in order, a phantom center is created with general success. An MTM seeks to create a phantom center using the vertical axis. So with all the things that most of us know, we must either have identical sources top and bottom, that are identically orientated above and below our ears, or we must use DSP to control the top and bottom separately to create the best results. No less than creating the optimal stereo image using the L and R channels, when done right, the results are impressive. With that same attitude towards tweaking the upper and lower woofers of the MTM you theoretically will create a point source like presentation. That is, all sounds seemingly, emanating from the center of the orientation. The increased efficiency is always welcome, of course. I speak to the critical listener as he/she is the one making sacrifices for SQ instead of looking for convenience are simplicity.
I listen close proximity so this is an easy way out for me to raise my crossover without loosing all the point source-ness of my low crossover. It also allows me to try some other creative ideas of decreasing excursion
I am starting to be under the impression that the MTM is actually the choice speaker for the purest/critical listener. I do not think that a typical crossover point of TM will be able to give a better image than an MTM would. The way I see it, a TM allows better dispersion above the Tweeter axis, this is something critical listener doesn't care about. MTM asks the listener to remain on axis to avoid the null created by the top or bottom woofer. This is something a critical listener doesn't care about. I should have pointed out this rant is geared towards large builds using large woofers and waveguides. With that in mind I am not convinced that a TM is able to give a point source like presentation in particular in vocals, in particular, the closer one chooses to sit. @IamJF Chose to get rid of his extra mid, but I would claim that the CTC is no where near that of a 15"+ large Waveguide.
I think what has me leaning towards the potential of MTM is listening to stereo monitors, period. When working at least somewhat in order, a phantom center is created with general success. An MTM seeks to create a phantom center using the vertical axis. So with all the things that most of us know, we must either have identical sources top and bottom, that are identically orientated above and below our ears, or we must use DSP to control the top and bottom separately to create the best results. No less than creating the optimal stereo image using the L and R channels, when done right, the results are impressive. With that same attitude towards tweaking the upper and lower woofers of the MTM you theoretically will create a point source like presentation. That is, all sounds seemingly, emanating from the center of the orientation. The increased efficiency is always welcome, of course. I speak to the critical listener as he/she is the one making sacrifices for SQ instead of looking for convenience are simplicity.
I listen close proximity so this is an easy way out for me to raise my crossover without loosing all the point source-ness of my low crossover. It also allows me to try some other creative ideas of decreasing excursion