Ask an Acoustic Engineer (me)

[Kb86]

Hi, thus what is the right way to keep it under control? Im using Carplay into head unit, then most adaptor toslink to Helix dsp. Should i keep volume on head unit around 70%, then control volume by Helix dsp? How to manage digital input? Is that control head unit volume is the same with control digital input? If i max out Head unit volume, does it mean i will max out digital input to dsp? What gonna happen doing it? Im a bit confuse.
Thanks.

[Justin Zazzi]

Hi, thus what is the right way to keep it under control? Im using Carplay into head unit, then most adaptor toslink to Helix dsp. Should i keep volume on head unit around 70%, then control volume by Helix dsp? How to manage digital input? Is that control head unit volume is the same with control digital input? If i max out Head unit volume, does it mean i will max out digital input to dsp? What gonna happen doing it? Im a bit confuse.
Thanks.

I have not used the equipment you have, so I'm not sure, but most digital devices can be run at any volume without problems.

My best guess if you should choose the volume knob you want to use, and then use it. If the system is not loud enough, then turn up the other volume knob. If the system is too loud or sounds bad, then turn down the other volume knob.

Your results may vary, I don't know how your equipment works.

[Kb86]

Thank you

[Kb86]

Hi Jazzi, on your new V2 curve, what measurements method you use? i assume u waving mic, but around each ear or half circle around head?

Also, do you use that curve for global eq or each side?

Please be specific because its vary alot. Thank you very much.

[Justin Zazzi]

Hi Jazzi, on your new V2 curve, what measurements method you use? i assume u waving mic, but around each ear or half circle around head?

Also, do you use that curve for global eq or each side?

Please be specific because its vary alot. Thank you very much.

Hi!

I measured that curve using a 6-mic array. You can replicate the result with a moving mic average, without sitting in the seat. I will sometimes sit in the rear seat and reach up to the front seat to do the moving mic average.

I did not use that curve as a target. That was measured as the sum total of my entire system playing.

[Kb86]

Thank you. it makes more sense now.
Could you explain further your tuning step?
1. Doing output EQ for each speaker?
How do you measure each speaker?
a. fix mix at headrest
b. moving mic while sitting in seat
c. mix array and averages?

2. Checking sum between speakers, how do you measure?
a. fix mix at headrest
b. moving mic while sitting in seat
c. mix array and averages?

The more specific the less confusing for us beginner. Thank you ��

[Justin Zazzi]

Thank you. it makes more sense now.
Could you explain further your tuning step?
1. Doing output EQ for each speaker?
How do you measure each speaker?
a. fix mix at headrest
b. moving mic while sitting in seat
c. mix array and averages?

2. Checking sum between speakers, how do you measure?
a. fix mix at headrest
b. moving mic while sitting in seat
c. mix array and averages?

The more specific the less confusing for us beginner. Thank you ��

Sure.

All measurements I do for frequency response are either moving mic method while sitting in the back seat, or using a 6-mic array when I was working at the office. They both measure very similarly. All measurements I do for time alignment or phase alignment is with a single microphone at the headrest, not moving.

My steps are:
-sanity checks, polarity, gain structure, and other setup steps
-equalize each speaker to the target, one at a time
-choose one speaker as my time alignment anchor (usually front left woofer)
-set time alignment and polarity of each speaker to match that anchor
-check speaker summing left and right in pairs (left and right woofers), then vs subwoofer
-play everything at the same time and check vs global target
-play bandwidth limited pink noise while sitting in the driver's seat
-adjust the relative left and right equalizers to center each of the pink noise tracks
-put the equipment away and play music I am familiar with
-make very small changes, if any

-sleep at least one night
-make small changes, if any
-sleep at least one night
-repeat

[Kb86]

Thank you very much

[Kb86]

Sure.

All measurements I do for frequency response are either moving mic method while sitting in the back seat, or using a 6-mic array when I was working at the office. They both measure very similarly. All measurements I do for time alignment or phase alignment is with a single microphone at the headrest, not moving.

My steps are:
-sanity checks, polarity, gain structure, and other setup steps
-equalize each speaker to the target, one at a time
-choose one speaker as my time alignment anchor (usually front left woofer)
-set time alignment and polarity of each speaker to match that anchor
-check speaker summing left and right in pairs (left and right woofers), then vs subwoofer
-play everything at the same time and check vs global target
-play bandwidth limited pink noise while sitting in the driver's seat
-adjust the relative left and right equalizers to center each of the pink noise tracks
-put the equipment away and play music I am familiar with
-make very small changes, if any

-sleep at least one night
-make small changes, if any
-sleep at least one night
-repeat

Hi Jazzi,

- How do you set time alignment? Do you fine tune the timing after initial TA? If yes, how would you fine tune timing? Ear?
- Is there any case you give up correct timing to exchange for other benefit (for example phase?)

Please be details.

Thank you very much.

[Jdunk54nl]

Hi Jazzi,

- How do you set time alignment? Do you fine tune the timing after initial TA? If yes, how would you fine tune timing? Ear?
- Is there any case you give up correct timing to exchange for other benefit (for example phase?)

Please be details.

Thank you very much.

Phase and time go hand in hand. The only way to be in time but out of phase is if polarity of one is wrong. Otherwise to be in phase means you are also in time with the other speaker(s).

Looking at a graph and getting everything as good as possible via a graph is always a good beginning goal that is repeatable. This is a great first start.

Once you have the graphs pretty (rta, magnitude, phase, etc), then you can put those tools away that you used to make those graphs. You have achieved your baseline goal. Now it's time to sit in the car in your normal position and use your next tool, your ears. This is where the "flavoring" of the sound comes in. I first start with band limited 1/3 octave pink periodic noise and listen to the speaker interaction and if something is pulling left or right. I adjust accordingly by increasing one channel and decreasing the opposite by the same amount to keep overall tonality the same.

Once I have all that lined up I go to my test tracks that I know very well. I listen to them and do global eq (with my helix I use the input eq for this since my input is flat and doesn't need eq, but you can also use your head units eq here) to flavor the sound for the environment I am listening in. This is the key, every install/environment/equipment choice makes a difference in this flavoring. If you tuned two systems to the same pretty graphs and then listened, there is a very good chance they sound different.

I know Justin's process is pretty similar.