Setting up my system now and will be using the factory head unit as my source. 2018 supercrew with non-sony with 8" screen and Sync 3. I know there will be some bass roll-off I will need to correct with Forscan. Does anyone know if Sync incorporates any all-pass filters? Or anything else I'll need to know regarding using the high level outputs to feed a DSP?

 

Are you using a dsp? If so which one?

 

I'll have the DD Audio DSI-3 with dash remote. 6 channels of input (either high or low level) to 12 channels of output (I'll be using 10 channels of output).

 

I tried looking in the manual and downloaded the ios app. I could not find all pass filters anywhere for this dsp, so with that, it wouldn't matter if there was an all pass on the system or not. You can't fix it (or apply the same to the other side).

You can check if you sum the signals to the sub, does the RTA results (measuring with something like JL Tun or REW and a USB mic) get better or worse when summed. I am assuming this would only be on the sub so easy to tell.

If you have a soundcard that can accept RCA inputs (motu, focusrite, etc), you could just send the rca out into the sound card and into your computer and check these things in real time with JL Tun or REW. Helix calls this method their "advanced input eq", but you can do it with any dsp. Just make sure all EQ, delay, etc is off. Then you can measure your head unit stuff easily, sum, etc.

 

Correct. The DSI-3 doesn't have APF capability for inputs or outputs. For that matter it doesn't have the ability to de-EQ the input at all to overcome any factory rolloff. I was going to use Forscan to address that. I figured if Sync 3 did have an APF incorporated by the factory someone could tell me if it's bypassable with Forscan as well. But if I can confirm that there is no APF from Ford then that's one less thing to worry about. On my HU there is a listening position option for driver or all-seats. Hoping that the "driver" selection incorporates only time alignment to improve driver's soundstage and imaging and not an APF as well.

These APFs are new to me but if I understand correctly OEMs use these to correct phase related issues in the upper frequencies as well. I'm concerned that if there is one active and I don't have the ability to correct it then my system will suffer from incurable dips in frequency response and I won't get the full potential of my gear.

I don't currently have a capable soundcard in my computer to where I could use REW or the like. What I have is an Audio Control DM-RTA which is new to me and I'm still learning. I am not sure if I can compare a summed signal to a single side to check for an APF. I'll look into that. I can look at an acoustical measurement of stereo vs mono but wouldn't be able to distinguish any dips from being caused by an APF or from reflection caused cancellations.

 

Can you return the dm rta? You don't need it and it's ability isn't great the way it sums every input. You'd be better off spending the money on a sound card and xlr microphone.

 

I do have an extra mic. It's a Dayton Emm6 and I have all the calibration data for it. I could get a sound card and get REW to use for all the acoustical measurements. But I gotta admit I'm a little intimidated by it. I've seen mention of it in other forums and it seems very complicated. That's why I got the DM as it's pretty strait forward. But I know it's limited. One thing I do like about it is the o-scope which I'm currently using to set my gains. But I imagine REW could do the same thing?

 

I forgot to mention in my previous post that Audio Control says you can identify APFs with the DM-RTA by measuring full range mono pink noise simultaneously and then individually to check for dips

 

I'm well aware of the product and what it can and can't do regardless of what ac claims or doesn't claim.
It wouldn't be my tool of choice, especially for the cost.

Unless you can measure phase directly via a dual channel fft (open sound meter, smaart, jl max and tun, rew with a loopback, etc), you are only guessing as to the all pass nature. What is the corner frequency and q value if second order all pass? If first order, what is the corner frequency? All of that information is necessary if you want to fix an all pass.

 

Understood. I am looking into the possibility of using REW on my laptop and what's needed to do so. Do you know if this particular interface would work? Behringer U-Control UCA222 USB Audio Interface - https://a.co/d/6QCLl7H