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Thread: Transfer function measurement

  1. Back To Top    #11
    Wave Shepherd - aka Jazzi Justin Zazzi's Avatar
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    Re: Transfer function measurement

    Hmm, maybe I misjudged your knowledge.

    If you are familiar with the tuning companion, bandwidth-limited pink noise, Andy's tuning guide, and you're comfortable with REW and the RTA in general .... how do you feel about using asymmetric crossover filters on the left side vs the right side?

    Also, do you know what your goal is? Do you know what you want your sound system to be like when you're done? Have you heard a system or a combination of systems and thought ... that is exactly what you want?

    If you have a concrete goal in mind, do you think you can get there with what you know right now? What do you think is stopping you?
    Measure with mics, mark with chalk, cut with torch, grind to fit, sand to finish, paint to match.
    Updated Justin tuning sheet (Justin and Erica tuning companion for SMAART and REW)
    Do it for them.

  2. Back To Top    #12

    Re: Transfer function measurement

    Those last questions are really good ones. I think I would really benefit from hearing other cars that sound amazing. I need to go to the next MECA events. That’s definitely on my list.

    As far as my goals, I’d like to forget I’m in a car...which probably will never happen but it’s a goal. I need to do some sound deadening as the little noises from the car bother me (as well as the road noise etc). That’s a big next step when I get some more money and I’m debating whether or not I should just take my car to Nick or read his guides and give it a shot. I like to DIY but I know it’s something you don’t want to have to redo...

    Also, I want to feel that the musicians are performing right there out in front of me, and to be able to pinpoint where they are. I also like to feel the music quite a bit so I tend to boost the low end 17-18 dB more than the flat middle part of my curve (this doesn’t help with me not noticing I’m in a car with rattles but I have ZERO deadening in place so I have hope).

    I don’t think the imaging is there yet to my system’s fullest capabilities. On my last tune I implemented very asymmetric crossovers to match the acoustic target slopes of each driver and I feel that helped a ton. I think I may have picked up on that from reading your build log. That was an awesome step forward (so thanks again).

    I also just implanted proper rear fill (finally switching the time alignment to delay mode in the helix) to be able to delay the rears about 20ms. Nick’s guide/video was extremely helpful in getting that done. That really did provide a sense of a larger performance space.

    I suppose I’m looking for those extra tips and tricks that people use to help identify hidden issues in a tune that take a car from sounding very good to “holy shit” with my above goals in mind. I realize some of that is subjective but I feel that some of it isn’t (like using band passed pink noise to get the imaging just right after the tune looks perfect with measurement).


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  3. Back To Top    #13
    Wave Shepherd - aka Jazzi Justin Zazzi's Avatar
    Location
    Northridge, CA
    Posts
    670
    Join Date
    Aug 2018

    Re: Transfer function measurement

    Quote Originally Posted by mauian View Post
    Those last questions are really good ones. I think I would really benefit from hearing other cars that sound amazing. I need to go to the next MECA events. That’s definitely on my list.

    As far as my goals, I’d like to forget I’m in a car...which probably will never happen but it’s a goal. I need to do some sound deadening as the little noises from the car bother me (as well as the road noise etc). That’s a big next step when I get some more money and I’m debating whether or not I should just take my car to Nick or read his guides and give it a shot. I like to DIY but I know it’s something you don’t want to have to redo...

    Also, I want to feel that the musicians are performing right there out in front of me, and to be able to pinpoint where they are. I also like to feel the music quite a bit so I tend to boost the low end 17-18 dB more than the flat middle part of my curve (this doesn’t help with me not noticing I’m in a car with rattles but I have ZERO deadening in place so I have hope).

    I don’t think the imaging is there yet to my system’s fullest capabilities. On my last tune I implemented very asymmetric crossovers to match the acoustic target slopes of each driver and I feel that helped a ton. I think I may have picked up on that from reading your build log. That was an awesome step forward (so thanks again).

    I also just implanted proper rear fill (finally switching the time alignment to delay mode in the helix) to be able to delay the rears about 20ms. Nick’s guide/video was extremely helpful in getting that done. That really did provide a sense of a larger performance space.

    I suppose I’m looking for those extra tips and tricks that people use to help identify hidden issues in a tune that take a car from sounding very good to “holy shit” with my above goals in mind. I realize some of that is subjective but I feel that some of it isn’t (like using band passed pink noise to get the imaging just right after the tune looks perfect with measurement).


    Sent from my iPhone using Tapatalk
    Wow, sounds like you know about my favorite tricks!

    In addition to going to MECA competitions, look for get-togethers too. Also take the judge's training if you ever get the chance. Even if you don't plan to judge a single event, the training is well worth it. I found judging cars to be a phenomenally helpful experience and an amazing way to train my ears. Learning how to listen critically and then clearly articulate what you are hearing onto a piece of paper is a skill that will serve you well.

    I agree about the sound treatment thing. If you have any doubts, and you can afford it, let someone with experience take care of that for you. It is certainly something you don't want to repeat. Also, try to be laser focused on what you want to accomplish with the treatments. If you give the car to a shop they might treat the doors and give it back to you but that won't help if the road noise is coming through the floorboards like on my Golf.

    A trick for treating specific buzz/squeak/rattle (or BSR) is to download a signal generator on your phone and very slowly sweep through the frequencies from low to high. If you go slow enough, you'll light up every single buzz in that car one at a time and then you can fix them as you go. You can also use this technique to narrow down that one buzz that only happens on a cold morning when your heater is on and you're making a left turn ... or whatever.

    I feel like imaging is the side effect of doing many fundamental things well. Imaging the frequency response to match very closely between the left and right channels and this is where the narrow pink noise tracks help. I was joking with a friend recently about putting some rocks on the dashboard and using them as a visual target when you're trying to center each of the pink noise tones, but it worked so well we call them "tuning stones" now haha.

    The other part of imaging that is tricky to get is goo time alignment between the left and right channels. The original Chesky Ultimate Demonstration disc is my favorite for this, but not for the music tracks! The narrator's voice is perfect for time alignment while listening to the lower frequencies, and also centering the image with the higher frequencies.

    Also, get other people to listen to your efforts. Nothing beats a second opinion, especially from someone you trust.
    Measure with mics, mark with chalk, cut with torch, grind to fit, sand to finish, paint to match.
    Updated Justin tuning sheet (Justin and Erica tuning companion for SMAART and REW)
    Do it for them.

  4. Back To Top    #14

    Re: Transfer function measurement

    I like the idea of tuning stones; definitely using that with my next tune ;-)

    I’ll also check out the judges training. Thanks again!


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