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The output from the Jag amp is interesting - but first a question - were the equalizer settings on the head unit all set to flat and centered between the seats prior to testing? If the mids were turned down in the head unit that could account for the drop you saw. If everything was flat and neutral for the Tune EQ and ATM testing then that is clearly on Jaguar and their factory settings.
Could the 160 Hz deviance be from phase cancellation? One thing I mentioned to @Jag Bass is that a few of my speakers had reversed polarity despite being wired perfectly (even using the AA battery test to determine cone direction during installation). I used three different methods to test polarity because I couldn't believe it. This leads me to conclude that the Helix DSP changes phase on some speakers during the virtual output processing. Can you test your polarity for your door woofers just to be sure?
It's not easy having to deal with the factory crossovers and roll offs as your incoming signal. If I did not have the Digital Ethernet Decoder I would just play lossless music through the HEC BT HD module that you have, which supports 96 kHz. But then you will need to do a new tune as that is a completely flat output and would not sound good!
Last thing to do is set your subs' T/A while sitting in the driver's seat and manually increasing the distance in the Helix PC Tool while listening until it is right in your face per this protocol (Post #8).
My understanding of all pass filters are that they can't be EQ'd out and he was able to flatten the 160. When playing the mid and tweet together the input graph indicated a cancelation at 2,000. No amount of phase shifting made it happy. He finally ignored it and it doesn't show up in the mic'd RTA.
I also double checked polarity with 9v battery and Speaker Pop at setup but I haven't gone back to check afterwards. I'll do that.
Chris didn't use the Helix to set the sub T/A, told me to just set the distance at 5 feet to push it up front. I'll have to check out your link.
My understanding of all pass filters are that they can't be EQ'd out and he was able to flatten the 160. When playing the mid and tweet together the input graph indicated a cancelation at 2,000. No amount of phase shifting made it happy. He finally ignored it and it doesn't show up in the mic'd RTA.
I also double checked polarity with 9v battery and Speaker Pop at setup but I haven't gone back to check afterwards. I'll do that.
Chris didn't use the Helix to set the sub T/A, told me to just set the distance at 5 feet to push it up front. I'll have to check out your link.
Once you identify whIch speaker the all pass filter is applied the same filter to the same speaker on the other side which will cancel it out.
Warm day. Took the car apart again. Put a layer of SoundShield around the rear 8's. Shoved everything back together. Going to need some new trim panel clips. But, huge difference in panels jumping around with the music. I basically used sound deadener as a sound proofer. Yes, I took my cue from mikelr's post. I figured it was worth a try.
@Robtrt8 Looking good after a lot of work - you essentially created a sealed sub enclosure using SoundShield while eliminating any rattles!
If you want to replace those OEM mids above the subs with something amazing, the 70 mm Audison AV 3.0 Voces fit perfectly into the octagon. I was surprised how good the sound is coming from the rear, but it makes sense how the human external ear canal is aligned.
Did you time align the subs while sitting in the driver seat yet?
A sub enclosure made out of semi ridged material is not exactly SOP in my mind which is why I was resistant to the idea but there is essentially two layers now and it definitely stops the panels from resonating. I can tell there's a ton more energy coming out from the drivers.
I do not have the rear fill mids hooked up. Keeping it old school stereo one seat tune.
Chris used the Helix DSP ATM feature on all the door drivers and the rear fill 8's. Physically measured the left mid as an input and let the DSP do it's thing. Huge improvement, sound stage is much wider. He did not include the way back sub. It's still set at 5 feet.
There is an easy way to get the midbass and bass in phase for up front bass. You can use the phase adjustment in the helix software.
Or I like to do it this way...
In the time alignment section
Link the subs in one group
Link all the other speakers together.
Play 80hz some wave . (I like to open the REW spl screen for extra verification)
Play the midbass and subs the same level. Like 90db each (mute the other speakers)
Using distance instead of delay in the TA software start increasing the distance of the subs. You will hear the bass sound like it’s coming up the drivers side of the car into the windshield then move across the windshield. You will hear it get louder and louder
while listening to the bass move up to the windshield watch the REW spl meter. It will peak at 96db or very close to it. Now you’ve got excellent up front bass.
If you want to make it even Better
Play a good midbass song and listen making tiny adjustments only 1to 2 clicks in both directions. I’ve found that about every 3 clicks in the TA they will snap perfectly into phase. The midbass drums will really snap
Even if you don’t do this final tweak it’s going to sound great to you!
But after a lot of practice and tuning you will be able to hear subtle changes in the tiniest of TA adjustments. I can hear a .02ms adjustment. There is several people in this forum that can also hear it.
Don’t be alarmed if your subs end up being 8-10’ away in the TA settings.
I first turned off my footwell Basslink plus all other speakers in the Helix software. I then played a 80 Hz tone while changing the T/A for the rear subs manually in the software. The bass moved from left to right and became louder and "in my face" at a certain point (like 8-10 feet). The 80 Hz wave is 14 feet long so physical distances are not applicable in sub T/A - it must be done by ear or SPL measurment. I then turned on the foot well Basslink and did the T/A on that using the same technique and with the rear subs playing as well. I stopped when the bass was in my face and noticeably louder (again, like 10 feet even though the right footwell is like 4 feet away). I last flipped the phase on each to make sure there were no cancellations and it sounded right. You have to do it to believe it!
