Tuning Related: How to connect REW/get pink noise from laptop into HU?

[mikes2017gt]

Rather than post this question in my build thread, I figured I'd post it here to make it easier for people to find.

I'm ready to start tuning my system/DSP using Room EQ Wizard (aka REW). REW has a built in pink noise/signal generator and using it would greatly simplify the tuning process. I have a 0dB pink noise file on a USB stick, but trying to play the file on a USB stick directly from the HU while trying to use REW would be very difficult if not impossible (I'm assuming as I've not actually tried it yet).

The HUs only AUX input is the USB port. Would be great if it also has a 3.5mm aux jack but it doesn't. Can you connect a dual-male-ended USB cable from the laptop to the HU? Do I need some kind USB interface?

Or, do I use a 3.5mm to stereo RCAs cable like this and connect the laptop directly to the DSPs input? Pretty sure I just answered my own question (LOL!), but I'd rather hear from those who've done this already.

Thanks in advance.

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[MegaG]

It is very laptop of more to the point sound card dependent (its why the mic from Audiofrog comes with a proven soundcard)
I bought a USB sound card (which looked a lot like the one in the AF mic kit) and couldn't get it to work easily and at that time had too many irons in the fire so I just played the pink noice through a CD or my phone using BT. Its not a bad place to start to get some readings. Sorry I couldn't be more help...

 

[mikes2017gt]

That's a good point regarding the laptop's sound card. The laptop I use for the car (including flashing ECU tunes) is an older HP laptop...an "office model" basically. Nothing special. I know the headphone jack works, but that's really all I know about it.

I do have a Komplete Audio 6 USB audio interface that I use with my main PC. I could easily disconnect it and use it with the laptop. *edit* Actually, no, I can't. The headphone output/monitor output doesn't work with a digital/USB input, it only works with the analog/MIC level inputs. I tried that several weeks ago when trying to plug headphones into it so I could rock out after the family was asleep and got nothing out of the headphones.

Would love some more input.

 

[mikes2017gt]

https://naviks.com/i-24076199-ford-...pter-compatible-with-all-sync-3-vehicles.html

There might be a cheaper option but this looks like what you want.

For $100 there better be tiny audio leprechauns in there, all doing real-time D/A conversion with 0 latency and brewing beer too.

 

[mikes2017gt]

I was more surprised anyone even made it. $100 isn’t what it used to be.

I just wish the webpage had more detail...any detail on it. How to use it, what it does, etc. They tell you nothing but "click here to buy." But thank you; I do appreciate your help.

 

[mikes2017gt]

There are lots of USB to 3.5mm converters, but they're designed to be plugged into a PC not an AUX IN on a HU.

So now I'm thinking: If the HU can recognize a USB stick and whatever "smart chips and circuitry) it has, it should be able to recognize something like this, no?

https://www.amazon.com/DuKabel-ProS...SB+TO+3.5MM+AUX+ADAPTER&qid=1603166024&sr=8-9

 

[mikes2017gt]

I always prefer to "Work smarter, not harder" and would really prefer to have REW provide all the test signals, but it doesn't look like that's possible. No big deal to load whatever test signals I need onto a USB stick. I already have 0dB, 40Hz and 1KHz test tones on there that I used for amp gain setting, as well as a 0dB pink noise track I loaded just in case. Looks like I'll be using it.

I can always also load sweeps, etc.

 

[Cathul]

Why is it so complicated to play the pink noise from your USB device and use REW on your laptop? I do that all the time. Just play that track on infinite repeat and go to town with your REW RTA feature.
It only gets complicated if you want to use sweeps for measuring impulse responses with acoustic timing reference, but not for regular RTA work with pink noise.

And connecting via USB will not work. I tried that myself and didn't get it to work.
In this case just use the cable from your picture and go directly into the DSP. You'll miss the delay from the headunit this way and frequency responses might be slightly different, therefor i would use this only for sweeps for timing measurements, phase measurements and stuff like that and stick with the USB stick and REW RTA for frequency measurements.

 

[mikes2017gt]

Thanks much, @Cathul .

 

[StangTime]

Why is it so complicated to play the pink noise from your USB device and use REW on your laptop? I do that all the time. Just play that track on infinite repeat and go to town with your REW RTA feature.
It only gets complicated if you want to use sweeps for measuring impulse responses with acoustic timing reference, but not for regular RTA work with pink noise.

And connecting via USB will not work. I tried that myself and didn't get it to work.
In this case just use the cable from your picture and go directly into the DSP. You'll miss the delay from the headunit this way and frequency responses might be slightly different, therefor i would use this only for sweeps for timing measurements, phase measurements and stuff like that and stick with the USB stick and REW RTA for frequency measurements.

This is the method I choose to use as well. Ideally you want to use the source unit input because there are small differences in the signal chain. 2 different A/D converters won't have identical audio properties.

You can get some basic high quality test tones right off JL Audio's website:
https://jlaudio.zendesk.com/hc/en-us/articles/235503327-Audio-Files

 

[mikes2017gt]

@StangTime So you play your test tones off a USB stick? You and Cathul make good points about the A/D converters being different. That could really make a difference.

For test tones, I use a program called NCH Tone Generator. It will generate .wav files of any tone/pink noise/sweep at any dB rating you choose. But thanks for the JL link.

 

[StangTime]

@StangTime So you play your test tones off a USB stick? You and Cathul make good points about the A/D converters being different. That could really make a difference.

For test tones, I use a program called NCH Tone Generator. It will generate .wav files of any tone/pink noise/sweep at any dB rating you choose. But thanks for the JL link.

Yes I play them from USB for RTA and level related tests. But like @Cathul said, if you plan on doing the impulse response measurements then you'll need to use the laptop output. I can't do this test as I have no way to re-route the signals in my DSP (you have to map the timing reference to the passenger side mid-bass for all test). The Twk should have the ability. I haven't been able to figure out how to impulse test from USB. I would need to somehow generate a WAV file with the timing reference and REW doesn't have this feature in the tone generator.

I will check out that tone generator you mentioned.

 

[Matti777]

I just downloaded the sound files from JL Audio's website and put them on a USB stick that came with my miniDSP

 

[Canoman]

Just for reference, Kicker has some test tones too.

https://www.kicker.com/test-tones

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