Home dbx User Forum dbx Archive Threads dbx Archive General dbx Archive General Discussion
Options

Advise on how I could setup best?

2»

Comments

  • Options
    DennisDennis Posts: 801
    Here's what I got doing the tops. My mic placement was more like 2ft out from the cabinets than 15". I didn't actually measure it and I see now in the txt you had feet not inches. I got that wrong from the numbers being in with the text and overlooked the hyphen. Typical machinist mistake. I don't know how much posting this screen captures will help but might as well show where I got. I'll put up the one where my mic was furthest away (about 5ft). I notice in the data now looking at it my delay to the tops grew smaller the further out the mic was. So my 8ms is going in the direction towards EAW's 6ms and when I did this with a spl meter I stopped at 6ms but it seemed as if it could end up being 7ms and I let it be at 6ms ever since then not having a better means for measurement. So I'll repeat this now and see what Smaart comes up with but here's what my screen looked like at about 5ft with 8ms delay to the mid/hi's.

    Judging from the 460 low phase trace, it looks like the offset delay is incorrect and too much delay has been applied to the 460 low itself. I think we should start with zero and go from there so remove any delay you added to the high, lows, and subs and repeat all of the steps I listed above. When is the gig you were concerned about?
  • Options
    DennisDennis Posts: 801
    I assume your measurement mic is connected to a mic input channel in your interface. Where are you taking your reference signal from? Is it connected to a line input channel in your interface?
  • Options
    My interface is the Smaart I/O http://www.rationalacoustics.com/pages/Smaart_I-O It's 2 in 2 out. I have ch1 mic input, ch2 input from aux out on my sound board. Pink noise is generated from the interface on output ch1 and into a channel on my board. I decided to try aligning the subs together today and see if I could get that right as it seems to make phase traces easier to read and less broken up when working with the same frequiencies. So here's that. Maybe you will be able to point out any errors easier as well. I started with my mic 15ft away measured this time and left it on the ground to measure just the subs. I started with the 400 and found my time delay with it. I noticed the time delay bounced around with track on and using find gave me different numbers but had no affect to phase trace once locked into a number. 27.83ms is where it landed the time I used it to make this first capture. The 400 is the brown line and has no processor delay. The 850 I captured with 6ms processor delay in purple and then turned it to what I felt looked like a better match and got 7.67ms delay in green.
    4001.jpg 180.8K
  • Options
    I tried some different mic positions to see how things got affected and got pretty much the same result. This pic is where I moved the mic closer to just 6ft away to see if there was any reflections getting in the way. Also I was playing around with the time delay in smaart and noticed if I entered my own number I could raise the phase trace so that I could see the entire dip in it without it being cut up. This didn't seem to affect measurements being taken here so I will post the result. Blue is the 400 and bright green is the 850 with 8ms delay in the processor. Dark green is the 850 with 6ms delay.
    4002.jpg 180.5K
  • Options
    Lastly I did one with the mic off the ground at about 5ft high and 15ft away. Purple is the 400 and pink is the 850 with 8ms delay. If these are looking good 8ms is coming out to be the common number. If I'm still way off can you give me an example pic of what everything should look like? The show is this saturday and I have good outlook weather the next few days so I should be able to get this done in time no problem. I also found out by finally getting a call from someone who has run sound there before that there isn't two 100A circuits they are 20's and only way I'm getting any more is to rent a distro with a bowtail cable and go right to the main on that panel which is close enough to do it safely. Idk if they will rent me one with that cable yet I'll find out later. So I'm not gonna be getting to run everything like I hoped anyway and I'm probably going to just have one 850 beside each stack and front aligned with the 400's. Makes everything a bit easier and I'm now sure I'm bringing more sound than this place has seen before which eases my worries now.
    4003.jpg 173.1K
  • Options
    DennisDennis Posts: 801
    My interface is the Smaart I/O http://www.rationalacoustics.com/pages/Smaart_I-O It's 2 in 2 out. I have ch1 mic input, ch2 input from aux out on my sound board. Pink noise is generated from the interface on output ch1 and into a channel on my board. I decided to try aligning the subs together today and see if I could get that right as it seems to make phase traces easier to read and less broken up when working with the same frequiencies. So here's that. Maybe you will be able to point out any errors easier as well. I started with my mic 15ft away measured this time and left it on the ground to measure just the subs. I started with the 400 and found my time delay with it. I noticed the time delay bounced around with track on and using find gave me different numbers but had no affect to phase trace once locked into a number. 27.83ms is where it landed the time I used it to make this first capture. The 400 is the brown line and has no processor delay. The 850 I captured with 6ms processor delay in purple and then turned it to what I felt looked like a better match and got 7.67ms delay in green.

    It looks like you have a handle on aligning the two different subs but you took the wrong path to get there. Using the "find" function at lower frequencies is not accurate and for subs, you have to depend on the Phase Trace. That is why I started with the high frequency. Calculate the offset delay with the horn and don't change it for the rest of your measurements (unless you move your mic and then it would be good to recalculate the offset on the 460 before proceding). Your reference signal should be from "mono" out or "wye" off of L or R out . Your offset number on the right side of the screen doesn't look right....30ms seems high.

    I am running out of time right now but will get back to you later.
  • Options
    Hmm well that explains my confusion of what's measured first to attain the time delay in Smaart. I was thinking the sub horn needed to be first as everything else was delayed from it. Ok well then here's one capture I left out. I followed the steps in order on this one but was getting a reflection bad from something and didn't have a second hand at the time to move the speakers so that's really kinda why I went on to the subs. Idk what I was getting back from so bad. Mailbox at the end of the drive? Tree off to the right? Idk but I do live in a cul-de-sac so my driveway is surrounded by houses and cars and I had my speakers pointed different this time so I could keep the mic on the drive but 15ft out. My coherence and magnitude dropped right where I needed it at my crossover point. Up untill that point the phase trace was looking perfect with the mid/lows at EAW's 6ms.
    460.jpg 165.8K
  • Options
    DennisDennis Posts: 801
    Also I was playing around with the time delay in smaart and noticed if I entered my own number I could raise the phase trace so that I could see the entire dip in it without it being cut up. This didn't seem to affect measurements being taken here so I will post the result.

    Click on the boarder of either the Phase Trace or Magnitude Trace window. You will see that causes the boarder to become high lighted. You can then scroll up and down in the selected window with the up and down arrow (or Page Up/Page Down....I can't remember which) and move the trace up and down without changing the delay value.

    The offset delay looks realistic now if your mic is 15' from the speaker and you also added 6ish ms to the 460.....remember you have to add it to the horn as well as the woofer.

    Report back when you retry the complete alignment
  • Options
    Had a nice day to spend all the time I needed working on this today. I setup pointing my speakers if different directions and got the coherence to flatten out good this time but still had those two big dips around 200 and 400Hz so I was unable to get a good crossover point to get crosshairs on. This prompted me to go ahead and check each 460 on it's side with a ground plane measurement and did all measurements from 15 ft away today. I found one cabinet looks like it needs a new mid driver. I'll post those captures in a new topic later. I then started from square one this time and went through all the steps in order, tho I had to align the phase traces so they followed along the entire trace instead of focusing on one very specific point where the speakers magnitude trace crosses over. I'd like to see an example of this if you may to see how a good alignment like this looks like. After making the stack I started with a fullrange capture using one amp and got a time delay of 16.98. Then I did a fullrange capture with it bi-ampd and EAW's processor delay's of 6 and 6.44ms and got a time delay of 23.44 in Smaart. The math shows a difference of 6.46ms in Smaart and with track on it was bouncing .02ms occasionally. Idk if those numbers represent anything of use but here's the capture anyway.
  • Options
    Next is the 460 lows aligned with the 400 and processor delay set at 6ms on the 460. To me this looks right and 6.44 and 6ms are good numbers. I moved the delay around on the 460 and the phase trace only got worse as far as matching. Only thing I could have tried different now that I think of it would have been to remove the 6ms delay then find the time delay in Smaart with the 460 at Zero and then capture the 400 phase trace. I didn't think of it till now tho as everything looked good where it's at.
  • Options
    Now for the 850. Using the same time delay in Smaart I got initally from the 460 I captured the 400 then displayed it static while sweeping the delay of the 850 and got 7.73ms delay in the processor to match best. Here's the result.
  • Options
    DennisDennis Posts: 801
    Had a nice day to spend all the time I needed working on this today. I setup pointing my speakers if different directions and got the coherence to flatten out good this time but still had those two big dips around 200 and 400Hz so I was unable to get a good crossover point to get crosshairs on. This prompted me to go ahead and check each 460 on it's side with a ground plane measurement and did all measurements from 15 ft away today. I found one cabinet looks like it needs a new mid driver. I'll post those captures in a new topic later. I then started from square one this time and went through all the steps in order, tho I had to align the phase traces so they followed along the entire trace instead of focusing on one very specific point where the speakers magnitude trace crosses over. I'd like to see an example of this if you may to see how a good alignment like this looks like. After making the stack I started with a fullrange capture using one amp and got a time delay of 16.98. Then I did a fullrange capture with it bi-ampd and EAW's processor delay's of 6 and 6.44ms and got a time delay of 23.44 in Smaart. The math shows a difference of 6.46ms in Smaart and with track on it was bouncing .02ms occasionally. Idk if those numbers represent anything of use but here's the capture anyway.

    In this first current capture that shows nulls at 200 and 400, how did you have the speakers set up and how did you position the mic?
  • Options
    The 460 on top of the 400 the fronts flush. The mic was at the height of the center of the compression driver which is between the mid horn and woofer and 15' away.
  • Options
    DennisDennis Posts: 801
    The 460 on top of the 400 the fronts flush. The mic was at the height of the center of the compression driver which is between the mid horn and woofer and 15' away.

    The nulls at 200 and 400 are reflections from the ground.......if you lay the 460 on the ground on its side, and aim the mic straight down with the capsule 1/8" from the ground, do the reflections go away?
  • Options
    Yes
  • Options
    GadgetGadget Posts: 4,915
    For safety sake make sure you have a way to secure the tops at the gig.. if one of those fell on someone... :(
  • Options
    DennisDennis Posts: 801
    Yes

    The purpose of baseline measurements is to correct the weak points of your speakers and system without venue issues cluttering up those measurements. You can deal with venue issues at the venue. My whole purpose in starting off with groundplane measurements is to obtain some clean traces that are easy to accurately calculate xo points and alignment with. Moving on to the mess a venue makes of the measurements is a second job but one that is easier to do after completing the baseline.

    Earlier in this thread, I listed some steps to take to align your system. The order of the steps was as important as the steps them selves

    When you look at Magnitude traces of individual components such as the horn, and you capture those traces you will probably see noticeable nulls at the xo points. When you look at a Magnitude trace of the entire system (after it has been aligned) you will probably see the nulls at the xo points have disappeared. This should be another thing you look for when adding/subtracting delay.

    The alignment of the 460 itself should not change once you are successful with your baseline. The alignment of your mismatched subs should not change in relation to each other but the alignment of your subs to your mains (460s) can change every venue.

    Thats all I got for now.
Sign In or Register to comment.