Time and Phase alignment of SPEAKER and SUBWOOFER using REW

[@Zachary_Setzer]

I'll keep saying it until you do it: a lot of us would be willing to pay a pretty penny for a full-blown audio calibration course. Just write and record it during your ample free time. 😂

[@NMP660]

We should start a "go fund Matthew" and raise a couple grand. I bet there's a good number of us that would chip in $50. Or, Matthew you could create an online course for a cost. I'd pay for it.

[@shaneb0422]

Just putting it on Udemy or similar would be cool Nice to get the trickle down through KZbin and it benefits creators but Udemy is a cool platform

[@dm17nc17]

Yes using rew for the competent diy crowd , I’d pay

[@PoesAcoustics]

Hah lack of free time is a big part of the problem. This is not simple. Having developed trainings in various fields/industries with professional adult learning specialists, I know what I am getting into. I recently heard a term that describes well a common and important concept for a training like this. Chunk and chew. You need to be able to chunk the learning into small bite sized pieces and then provide hands on opportunity to “chew” on it. I would need to create learning objectives, an outline, and then work through a lot of material/content. Figure out the right breakup of chunks, and then develop what is probably 100’s of activities. I then need to figure out a way to provide you with an ability to do their activities remotely and for me or an automated system to check the work and provide useful feedback. Otherwise my concern so that this will be a firehouse of information that will be misunderstood and misused. It will muddy the waters and not really achieve my goals in putting in the work. And to add to that, there is some potential loss of work from this. I get mixed advice on this. Some say that this is what differentiates me from others and to not give too much away. Others say that this just reinforces why I am different and that my customers would understand that if I can train this, I am going to be the best at doing it. The classic, which do you want, master or apprentice. I side with the latter argument but then the total Money needs to accommodate my effort and loss of work. In my opinion, the total hours of work that would go into this and the total value of the knowledge is equal to a larger amount of money than I think I could raise for this. But I am not against trying and have already talked to folks about this. I suspect I will start with in person trainings as a way to refine the content and then develop it into an online modular based system that can be tied to an online education platform that has tools for chunk and chew like learning.

[@Zachary_Setzer]

@@PoesAcoustics Thanks for the thoughtful reply. Happy to see you've been thinking about this. I'm going to go ahead and ask your pardon for the unsolicited advice below. Take it as one perspective from someone who has received a lot of value from your work. You're really the only person properly situated in the space to do something like this. Hard to see anyone further up the pecking order (like Anthony) doing anything like this, and anyone further down the pecking order wouldn't have right combination of technical expertise, hands-on experience, reputation, and heart for teaching. Sounds like it would be an excellent course. That degree of detail sounds perfect for the experienced DIYer or for professionals looking to up their game. I gather there are a fair number of people out there doing audio calibrations who don't have an advanced level of expertise. Given your reputation in the industry and your burgeoning reputation online with consumers directly, maybe you could even do a Poes Acoustics Academy certification for people who have completed the course. You could start think about pricing strategies where you curate a basic track from the overall course to offer to people just wanting to get the fundamentals right (priced maybe $100-$200), and offer the full-blown, deep dive with certificate to obsessive DIYers and professionals at a much higher price (maybe $2,000-$3,000?). You could run a Kickstarter campaign to see if it's financially viable before putting in the work to create it. I'm sure your friends in the YT community would let their audiences know about it.

[@MrBonger88]

Yes, please do a video on proper subwoofer integration 😊

[@pulDag]

I was asking that myself for years. Thank you Matt

[@adrianadrianp5305]

Be amazing to see a video walking through alignment using REW with a more detailed explanation as you look at graphs etc

[@mikeortiz2139]

Being a visual learner, are there any example videos you could point me to or would a part II with screenshots be possible? Thanks.

[@kapooranuj]

Hey Dr Sound! Besides the long pending sub integration... A detailed REW video is really really needed.. Please.

[@shaneb0422]

Have you investigated or tested A1 Evo with Audessey yet?

[@sagi_tech_n_stuff]

So does the phase knob on a subwoofer only control phase or is it a mislabeled delay control? Thanks

[@nowayman1981]

On fire with your post consistency!!! Super appreciated as always learn something new 🤘

[@gg.6967]

😄😁😄more Poe acoustics

[@simpsonbergman2185]

Thanks! Thanks for your input on my question! I have another one:) What I'm finding is that no single time delay gives a great match between the two impulse responses. Due to the duration of the impulse response, I can set the relative delay so that the first half of the impulse responses match very well, but the second half of the impulse responses are then out of phase. (I'm looking at the impulse responses at particular frequencies.) I understand that this implies a need for a more involved filter, e.g., allpass filtering. Do you have an opinion about Dirac bass control for this? [I am using a minidsp flex for stereo with 2 subwoofers. Dirac bass control is not available for Minidsp. I'm thinking of bringing a computer into the system to run Dirac with bass control, and getting a four channel DAC to then feed the 2 speakers and 2 subwoofers. I originally wanted to avoid using a computer, but I'm now considering it. I don't really want to get an AVR since I already have a hypex stereo amplifier and an AVR with Dirac license is quite expensive and I guess overkill for a stereo-only audio system.] (Sorry for the lengthy question!) By the way, REW lists 3 different wavelets. I try teach one, they give quite similar results, but do you have a preferred wavelet?

[@simpsonbergman2185]

Ah, I watched again your video "Top automated EQ for multiple subwoofers" where you talked about Dirac live with bass control. I think I will try the free stand alone trial after I get a 4 channel DAC. Thanks for sharing your knowledge and experience on these topics.

[@scott1063]

Graphs would be nice.

[@welderfixer]

Anyone else also think "The more I learn about home theater setup, the less I want to do it."? Just run Room Correction, open a beer and try to enjoy a movie. The more you drink the better the system sounds. HAHAHA! Anyway - Thanks Matt!

[@ChadAV69]

There's a learning curve to it but once you get over the hump you get really good results easily.

[@welderfixer]

@@ChadAV69 Yes sir. I've been at working on my multi channel system(s) for well over 15 years and the seemingly endless tuning and upgrades are getting tiresome. Every time I think I'm happy, Satan whispers in my ear: "Is it really right?". That SOB needs to SHUT UP! HAHAHA Hopefully, I can get enough time to sit down with REW and get much better at using it. Very powerful software package. All the best to you and yours, Kevin

[@KimmoJaskari]

At the end of the day, just buying the gear, connecting it up and watching a movie is a huge step up and it's going to sound great out of the box. Hell, even without running Audyssey or anything you get something enjoyable. Getting it all fully dialed in, the sub(s) put in the right places to tame room modes, running corrections etc will of course pay huge dividends but the first step is just starting. Even if that's just getting some entry level noise makers, a hobbyist can start small and then grow. Just getting from plain TV speakers to a stereo pair of speakers is a big improvement, you can go from there. But yeah - it gets technical fast. Which is why there are calibrators etc for hire.

[@PoesAcoustics]

I don’t know if I agree with the first part of this. Just connecting the gear and playing it out of the box would likely yield pretty poor results. Sure the wider bandwidth will probably lead to better than TV sound. But it’s like saying a Ferrari with plastic sleeves on the tires would be an amazing driving experience with no need to touch it. Or a race car that is build but never tuned at all would still provide an amazing driving experience. High performance kit pulled together and not optimized at all will more likely than not yield poor results that could be bettered easily by equipment more designed for such simplistic operation. I do agree that just running Audyssey or similar is going to be better than nothing and likely yield pretty good results. While much better can be achieved. When you put it into perspective, we are talking about good gear that is now time aligned, level matched, and eqed. Is it the best it can be? No! Is it a heck of a lot better than nothing? Absolutely and for most that would be really good.

[@davidjalsoviczky6055]

Thanks again for this great video. When you mention the Alignment tool in REW, there are 2 options, Phase alignment and Impulse alignment. You are talking about the Phase alignment, right?

[@PoesAcoustics]

Yes. The phase alignment. The impulse alignment will not work correctly between a full range speaker and subwoofer. It’s best for aligning two full range speakers. The problem becomes obvious if you look at the impulse response of a subwoofer vs full range speaker.

[@davidjalsoviczky6055]

@@PoesAcoustics yes, got confused real quick, that is why I wanted to double check with you. Are you going to the ISE in 2025?

[@jglaserbot]

Thank you as always for your information. I’ve recently purchased some Rel subs and John Hunter of Rel discusses alot about their Rel 3D system which is supposed to be a take on Ray Dolby’s vision of having full range speakers 20-20K Hz for theater. Rel’s basic concept is using three subs minimum, which consists of 1 sub for the mains and 1 sub for the rears using their high level connection along with the LFE connection and then the third sub would be located near the center speaker hooked up high level only. I’m curious to your thoughts on this as I understand the concept they’re trying to do but the implementation of getting it all to work seamlessly seems daunting.

[@ChadAV69]

I have never used the spectrogram in REW but I'll check it out. Thanks. I have been just using the alignment tool to impulse align the sub to my center and then I use AP filter to fix around the xover point.

[@BobFrostV]

This is the best content 😆 But, I know everyone can't handle it lol

[@garyharper2943]

So true, over my head most of the time, like when I took quantum mechanics in College.

[@steakhoux]

I also had those problems. My MSO optimized array has different group delay than my mains below 70Hz. My solution was to raise the XO frequency to circumvent this area and have the XO where GD was more similar. If possible it can also be helpful to use 48 db per octave filters so that proper phase alignment only has to be +- 0.5 octaves around the XO. All pass filters are really helpful especially because you can use them for each channel. It would be nice if Trinnov would add them in the PEW section. :)

[@DearSX]

Thank you!

[@PoesAcoustics]

You're welcome!

[@NicolaeLorimer]

Thanks!

[@PoesAcoustics]

Welcome!

[@kewlbug]

The processor in my car uses an All Pass with a Q of 1 for the adjustable phase, the 180 point on the adjustment centered at the crossover point. moves the Allpass up and down to correlate with the indication, and moves with the crossover if you change that. I would assume these home units are doing similar. That said, I almost never ever touch it. I will time align the slopes using both the 0 and the 180. whichever one makes the most sense for the distances and response is what I go with. And usually matches slope over the longest bandwidth. (Level phase at cursor button extremely helpful) I DO need to utilize the spectogram more. Just to check my work really. The allpass/active phase adkustment, might be more helpful if you have Smaart or similar to watch the changes live. Otherwise its a guess and check process...

[@gbye007]

Where's the wavelet feature in REW? I found it - it's a mode within the Spectrogram tool. It would be sueful to have a talk on what this tool is showing us.

[@tomashelland2855]

At least show us on your pc how you get this right🤣 some of us need to see it, to get it🙈 sadly😂

[@danjones4002]

Here is where tech makes things complicated. Luckily i learned the old school way, and almost always it ends up getting me the best results. Every one should try this. Start by getting your tape measure out and try to figure out what your delay/time alignment "should" be. Flip phase on your sub. Now play the tone of your crossover frequency through both the mains and sub. Get you db meter out and add delay or take away untill your db meter shows the lowest db. When you find that.... flip phase of the sub and bobs your uncle!

[@PoesAcoustics]

And what do you do when the DSP latency makes the delay 10-20-30ms worse than the physical distance and you don’t know what the latency is?

[@MilGrip76]

Details, shmetails... just use the "squat and nod" method as a certain alphabet company uses, they sell really expensive stuff... so it must be right, right?😅

[@TheLkdude]

Given your expertise and the need to be mindful of time, I encourage you to provide explanations that are both useful and valuable. This isn't a criticism-just a request! As you can see below, there is a strong demand for this content. It could be helpful to consider a demonstration or, at the very least, a visual explanation to enhance understanding.

[@BbbVvv-p7x]

You speak a lot and no practical showcase..

[@WillyLax24]

Thanks!

[@PoesAcoustics]

Welcome!