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Wave Shepherd
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Discussion Starter #301
I'm always looking for side projects to work on. If you'd be willing to let the source be available on a public github, I'd be down to work on it. Been looking for an excuse to do an all js site using node for server side and maybe Angular for the client. Working with Canvasjs would also be cool.

PM me if you're interested. Only one partially complete project up there, but youre more than welcome to take a look - github: ddpdoj.

-Nathan

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I know enough about github to know that I don't know how it works. Maybe you can teach me? Lets talk some more over PM.

-JZ
 

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Other than some Matlab code I used to prototype some features (more expensive than excel haha) I do not have any other versions of this tool, nor do I know of any. I have too many projects to port this to OpenOffice or any of the Excel replacement programs.

If you want to pursue a port I can offer some help, and you might find this page to be useful (maybe):
https://ask.libreoffice.org/en/question/6621/import-ms-word-macros/?answer=6982#post-id-6982

I feel your pain, I truly do. I don't enjoy having to purchase Excel and Word by default, but thankfully they are more affordable than ever and they still have perpetual licences available instead of the "pay forever" model that is absolute bullshit. The VBA scripting that Excel offers, the limitless ways it can hook into literally anything, and the absurd amount of support available from other folks using VBA code is impossible to beat. For example I'm also using VBA code to automate a massive script to run the Klippel Distortion Analyzer stand-alone which is really darn cool.

However, I do have a website I could host a port of my tools on. The last time I programmed website stuff was a long time ago so I could eventually get it done in a year or two at my own pace as I struggle through it. I would welcome ANY help to port these tools to php/javascript/html/java etc to run on a website. I have a dedicated server with just about anything needed, I just don't have the time myself to dig into this.

The VBA scripting portion of my spreadsheet is dirt simple. I would specifically need help with the graphing and displaying of the information, along with the calculations done in the background preferably with something like php that runs on the server side, or whatever the equivalent is these days.
VBA scripting, however simple, is over my head, for now.
I am not requesting that you port it, I just had to ask if someone had already done so. I might look into trying it at some point, as I said everything works perfectly except external file handling.
Again, thanks for the good work.

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My system is "semi" active (?) using a sub and a passive component pair with a miniDSP2x4. TA is adjusted for the LR components using the mid-bass distance.

After REW EQ, it seems cancellation is at crossover point between Sub and mid-bass. In addition, a big dip @400 Hz-500Hz can not be EQed.

Could anyone tell me how to solve the problems.

Many thanks!
 

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My system is "semi" active (?) using a sub and a passive component pair with a miniDSP2x4. TA is adjusted for the LR components using the mid-bass distance.

After REW EQ, it seems cancellation is at crossover point between Sub and mid-bass. In addition, a big dip @400 Hz-500Hz can not be EQed.

Could anyone tell me how to solve the problems.

Many thanks!
I suggest switching polarity on either your sub or midbass to fix your crossover dip, or use linkwitz-riley crossovers if your minidsp 2x4 has that option and you're not using it. Your dip at 400hz should be ignored if you can't hear it, it is likely a phase issue that would require moving speaker mounting locations.

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Wave Shepherd
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Discussion Starter #306
Yep, trying flipping the polarity of the subwoofer. If that doesn't help, try searching for the technique called nulling to help you adjust time alignment in real-time with the RTA module within REW.
 

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Wave Shepherd
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Discussion Starter #307

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Still new to the forums! I think I have only posted once before. Got logged back in because I wanted to post to thank Jazzi for the great tool created and show my REW graphs and see what everyone thinks. I know there is some room for improvement but I am happy with the results from this for now. Seems like there are a few issues in the low end section. The Subwoofer I have isn't very powerful so it seems like I would have to run it super hot and do a lot of cutting from 45-80hz to get it to properly flow the curve or do what I have done now, running it not so hot and cutting a bit less. Also no idea what is causing my dip around 140hz. I have played with phasing with the sub and mids and can't get it to go away.

Car: 2013 Chevy Volt, Stock Head unit with Bose option
Gear:.
Morel Maximo Ultra 6.5
Kenwood KSC-SW11 under seat subwoofer
Alpine MVR-F300 Amp
MiniDSP C 6x8
MiniDSP umik-1

jazzi.jpg

jazziwaterfall.jpg
 

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Wave Shepherd
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Discussion Starter #309
Hey there killeraxemannic, you're welcome! I'm glad you find this tool useful.

Most subwoofers in a car cannot play "flat" and still sound good according to the house curves that most people like, so you're right that you would need to boost it hard in the lowest frequencies and then cut in the 45-80hz region. This is not uncommon!

To learn more about the dip around 140hz, you can try playing one speaker at a time. If the dip is present when only one speaker is playing, then you have a problem with your installation, likely caused by a standing wave due to the dimensions of the interior and where the speaker is mounted. If you only have a dip when more than one speaker is playing, then you have an interference problem that can be addressed with manipulating the phase of one or more of the speakers.
 

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If you only have a dip when more than one speaker is playing, then you have an interference problem that can be addressed with manipulating the phase of one or more of the speakers.
Could this be fixed by better time alignment, or electronically switching phase only?
 

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*Assuming your arrival times and your polarity between the drivers are set correctly*, adjusting delay to "fill" in a hole in response is a bad idea. You'll just wind up with more combing (peaks/dips) because you've taken what was two signals and put them in-phase via time and now knocked them out of phase some amount.

I have more I can add regarding the phase/time relationship but I don't have the time (no pun intended) at this moment. And I'm not sure it's necessary.



Otherwise, like Jazzi said, look at the response of each driver by itself. Then look at the combination. You'll most likely find that one driver has a bad dip in response on its own and you can't fix it.
 

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The dip at 140 Hz is in the speakers. Here's all of the individual measurements overlayed together before EQ. Not much else to do on the install. My doors are sound deadened and I used butyl rubber to seal the adapter plates to the doors and put sound deadener around the adapter rings. Also used fast rings on the front side where the speakers meet the door panel
 

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*Assuming your arrival times and your polarity between the drivers are set correctly*, adjusting delay to "fill" in a hole in response is a bad idea. You'll just wind up with more combing (peaks/dips) because you've taken what was two signals and put them in-phase via time and now knocked them out of phase some amount.
...
To be pedantic...
It would be possible to use a group delay type of FIR to alter just a narrow frequency band and shift only that band over in time.

Personally I would not do it, but that is about the only way to accomplish it without moving the speaker's whole frequency band in time.
 

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Are you talking about using an all-pass filter? if so, that will also effect other frequencies as well and while it may fix the 140hz null, it will cause issues elsewhere. The all pass is designed to adjust phase over a band of frequencies. In which case, this is not the optimal solution for his issue. Not unless he has access to a very high order all-pass filter; and I couldn't tell you how high it would need to be other than well over anything I've ever used (which is no higher than 2nd order).

The only way the all pass filter would work is if the mixture of speakers is the cause, but in this case the issue is most likely rooted in the environment (i.e., a hard reflection from the center console, or the PLD between the listener-speaker-ceiling, etc) and an all pass filter won't reconcile that and provide him with a smoother response in this region.
 

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Are you talking about using an all-pass filter? if so, that will also effect other frequencies as well and while it may fix the 140hz null, it will cause issues elsewhere. The all pass is designed to adjust phase over a band of frequencies. In which case, this is not the optimal solution for his issue. Not unless he has access to a very high order all-pass filter; and I couldn't tell you how high it would need to be other than well over anything I've ever used (which is no higher than 2nd order).

The only way the all pass filter would work is if the mixture of speakers is the cause, but in this case the issue is most likely rooted in the environment (i.e., a hard reflection from the center console, or the PLD between the listener-speaker-ceiling, etc) and an all pass filter won't reconcile that and provide him with a smoother response in this region.
Not an all pass filter Erin...
Almost every 8.11 modem known to man has a channel calibration that tries to recover an impulse response, and this decolors group delay in the channel.

https://en.wikipedia.org/wiki/Group_delay_and_phase_delay

https://www.mathworks.com/help/signal/ug/compensate-for-delay-and-distortion-introduced-by-filters.html

And the group delay is 'always' minimized.
However one could, in theory, intentionally go for a group delay that was not minimized over some band.

Of course I have never heard of anyone doing that... Usually the group delay is off and one calibrates the channel to improve it, not make it worse.

So I do not know why one would do that, unless in this special case it made sense... It seems easier selecting a different driver (or placement) as well as those being quicker to achieve... unless one was already a DSP guru and had 'mad-skillz'.

And they would need a FIR based DSP. :cool:
 

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Wave Shepherd
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Discussion Starter #316
Almost every 8.11 modem known to man has a channel calibration that tries to recover an impulse response, and this decolors group delay in the channel.
Cool discussion, keep it going, but what is an 8.11 modem?
 

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Cool discussion, keep it going, but what is an 8.11 modem?
Sorry 802.11 (A through whatever)...

fred harris literally wrote the book on FFT windowing, DSP and multirate processing (as did Rabinier, Rader, Schaffer, and others).

https://en.wikipedia.org/wiki/Fredric_J._Harris

fred harris specifically mentioned to me in a course on DSP how his methods are used in the modems for decolouring a channel's transfer function by minimizing group delay.

While he is much smarter than I am, I know enough to understand the theory and how it could be done in the case mentioned.
(But again no one would actually do that, so it is a bit of a pedantic-wank... but knowing it is actually theoretically possible - seemed worth a mention... even if it )
 

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Hi guys,

I did some re tuning the other night and I think I got my response curve to look a little bit better. I ended up adding a bit of boost (+5DB around 20 and 40 hz) to the sub on the lower end to flatten out that curve. I also moved my crossover down from LR24 3000hz to LR24 at 2900hz. Seems like the crossover point matches the Jazzi curve a little bit better. I also dropped my input filters completely and thats kind of where my question lies

The miniDSP allows you to EQ each input channel and each output channel and get 6 filters per speaker on the output side and per side on the input side. I have been doing my output EQ's first and then doing my Input EQ's after and have just been doing an overall curve that is the same for both input channels. I would assume that's probably not the best way to do it. It was giving me pretty good overall curves (I think) but I would guess you want to EQ both sides of the input individually after you EQ all of your outputs to each individual speaker? Or maybe EQing the input is a bad idea all together... Not sure

Before with the 3000hz crossover my responses still looked pretty ugly. Last night I was able to get a pretty good response tuned in without any input EQ curve at all. The photo I have attached is my curve from last night.

Would it be beneficial to tune the inputs for each side now? Like run them through REW Auto EQ with the full Jazzi house curve set? I would assume I would just want to cut the peaks between 200-300hz, 1k-2k, and 3k-6k? Or should I just try to tune those out by further adjusting my output EQ's? Also am I doing this backwards? Should I be tuning the inputs first? I guess I also really don't know how tight of a curve I should be trying for and where you would be hitting the point where you are just wasting time.
 

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Wave Shepherd
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Discussion Starter #319 (Edited)
Good questions! There are many ways to use filters on a DSP, and no "bad" way if it works.

After tuning multiple cars, I like to use the filters on the individual channels for tuning (to make the individual speakers play nicely with each other), and using any input or global filters for toning (to adjust the overall tone curve or flavor curve as I call it in the tool, actually tone curve makes much more sense). This lets me completely separate the technical aspects per-speaker which can only be setup one correct way (so all the speakers sum together correctly), from the subjective tone curve which can vary widely person to person, even day to day. Then when I inevitably decide I want a little more of this or a little less of that, I can tweak the input EQ a little and all the technical tuning stays correct. Actually I tweak the EQ on my head unit since it's easy to do while I'm driving and doesn't require a laptop, and it accomplishes the exact same thing.

Side note, this is exactly what the JBL MS8 did. All the technical tuning was done automatically for folks who didn't know how, and the subjective toning was available to play with using the 31-band EQ that was available. The user-adjustable EQ was effectively the same as an input EQ since it was global. I believe this wasn't very popular since people didn't understand it and also since the auto-tune algorithm was pretty darn good, but not as good as a really talented tuner could do manually, and there was no way to bridge the gap since the auto-tune settings were hidden from the user and not adjustable.

Whatever technique you decide to use, I find being economical with each and every filter is a really important skill to have. No matter what you do, you'll always wish you had one or two more filters available somewhere. So if you can learn how to combine the effects of four filters into just three, or four filters into three while also changing the crossover a little bit, then you free up that one spare filter for later and sometimes it makes all the difference :)

edit: oops, forgot about your graph. Peaks are easier to hear than dips, and broad peaks/dips are easier to hear than narrow ones. So you might try some super broad EQ filters (very small Q<1) to boost at around 25hz, and cut around 95hz, 290hz, 1.8khz, and 4.2khz. Your results may vary.
 

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I saw some people saying earlier in the thread that they didn't want to pay for Office to use the tool. You can actually buy a legit copy of office off of ebay for around $10. I have bought quite a few Windows 10 and Office 2016 licenses off of ebay and haven't had any issues with them so far. They basically just send you the keycode in the email and then a download link to the installer.
 
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