See if this will work...

https://www.minidsp.com/images/fbfiles/files/All_digital_coefs_v1-20101026.zip

 

Thank you but that goes from basic to biquad and not the other way. I could look at the formulae and rewrite the inverse but hoping that someone out there has already done this.

 

Ah ok, I wasn't sure if it world work in reverse.

 

I am reading that it is not always possible to reverse. Moreover, the basic EQ in minidsp only allows peak, low shelf, and high shelf. I wonder if in REW the autoEQ is allowing other types of filters to be applied which would make my point moot.

So the next question is: if I am close to a good tune with the biquad coefficients but want to tweak them, how do I go about doing this easily? It almost seems as if I have to either scrap the tune and start over or estimate the filters to plug into the minidsp.

 

What I have done, don’t know if correct, is to substitute......

I have copied all of the biquads over to Evernote on the Mac - labeled them so I know what I’m looking at.

Then use another preset, do the Basic of the new value I want - hit Advanced - copy that and paste into Evernote.

Then copy in that part of the Biquad into the advanced filter I’m trying to tweak.

I did this the other day - had an 80hz filter for the sub (had the other filters (mid bass and mid range) in there to complete the Biquad) - and wanted to change the low pass of the sub to 60hz.


Sent from my iPhone using Tapatalk Pro

 

Thanks. What I did so far is go into the PEQ setting of each driver which listed the biquad values. I turned off each filter and tried to match by eyeball each filter individually and then turn them all back on make sure the overall shapes matched. I then went out and listened side by side with the biquad filters in one dsp configuration and then the other configuration with my manually matched filters. It was close enough that I couldnt tell. SO problem solved: not nice and neat but worked well enough to get me into the ball park that now I can mess around with each filter easily by hand. Which leads me to my next question. (Rather not start another post)

I now have the following over all curve:

This is 1/6 smoothed. It sounds pretty good but I'd like to dial it in more. Notice the dip at 80 Hz. I have the sub crossing at 65 db and the midrange crossing at 80 db, using a 24 db/octave x-over. I tried moving the mid xover up and down but no help. Tried increasing gain on the sub at 80 Hz or so and no budge. Any ideas? I havent dialed inthe timing with sub other than measuring tape. I plan to flip the polarity and then increase timing until it gets quietest and then flip the polarity back.

Also, the bumps in the 2k - 4 k range plus the dip around 500 Hz. I have used all my filters on the input and output. So what now. It is probable that I am not using them the most efficiently but how would you proceed here? Should I go flat on the input side of the dsp and then start over there?

How about that upper end? It drops off severely after 10k. I dont really seem to notice but who knows what I am missing? Maybe a shelf filter there?

 

It drops off severely after 10k. I dont really seem to notice but who knows what I am missing

Mine does that as well, just drops right off at 10k. I wonder if it is a setting in REW that we are missing.

 

A 45db delta between 20-20khz is quite extreme ...
Are you trying to de-eq a factory radio?
What target curve are you aiming for?

 

Yeah, it is extreme and I am planning to start over again tomorrow. Although this tune curve is what actually sounded best in my vehicle so far; it does look extreme. I had one other tune, the one prior to this, that matched the audiofrog more closely but it sounded like absolute garbage. Maybe I just needed to tweak that one. But, I felt that the drop off from the sub to the woofer was too steep and the upper end was fatiguing my ears.

I was recording a 32 average of the RTA signal for each driver and saving it to the measurement tab, then EQ against an audiofrog house curve: driver by driver to maximize the number of filters I can use. The audiofrog instructions (if I understand correctly) are to bring the house curve into RTA, not save after a sweep and EQ in the other tab. I think this will be easier: adjust the filters on the fly. But more important is that I see the instructions are to EQ one side to the house curve and then EQ the other side to the first not the house curve.

I am not sure why there is such a severe drop off on the high end. I have a notch type filter around 13k. I have to check all that out though. I am thinking I might need a shelf filter on the upper end to bring it all up with progressive gain the higher up in Hz.

I think a fundamental problem is that the Fs of my tweeter is 3.2kHz. So I am reading I should crossover at 1.5 - 2 times that at least. That pushes a lot of upper end onto the 6.5 inch woofers.

Plan tomorrow is start with a flat EQ and take a full right and full left measurement. Then both together. I am thinking of trying to address any bigger issues on the input side (along with overall levels) of the minidsp as that allows a broad stroke in the form of a left EQ and a right EQ. Then focus on the right side and get close the audiofrog curve, maybe a more shallow slope through the sub to woofer transition. Then focus on getting the left side to match the right side. Cross fingers and put on music.

I am very open to suggestions on how to improve my workflow or process.