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mtm to tmm 2way

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  • #16
    Your schemo. looks good.

    solen.ca is in Ontario - and they're purported to carry Dayton stuff - but I tried going there and 1st got redirected to update my firefox (locked machine up!), tried a diff. link and got some err 404.
    Maybe just call them and ask for a catalog??? (tell 'em their URL got hijacked?)

    They do have a facebook page, but I don't do that.

    - try solen.ca/products

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    • #17
      Thanks Chris- I can email Chris at Solen he sold me the Nextels I did not see the iron core inductors on his site. thank you again.
      Ben

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      • #18
        Originally posted by top gnome View Post
        thank you here is a photo of the set up I do my woodworking glue ups in the same room so keep cardboard on the floor. That is also the reason I am thinking about TMM because some of my listening is done standing up
        So, all measurements were taken on that speaker baffle?

        I see a couple ways to improve the measurements. Tilt the tv screen such that the top edge points slightly in front of the speaker, so that any sound from the speaker is reflected away from the mic.

        Find a suitable box, and stand the speaker on it. Get the tweeter up to about 48" from the floor. If your ceiling is more than 8', raise the speaker even more.

        If you have speaker stands, you could turn the box sideways. That gets both woofers further from ceiling and floor. (Sill need 48"above floor.) Be careful not to drop it on anything, like pets, children, your foot, etc.

        I can't tell if there's anything to the right side, but if not, it looks like you could move the speaker maybe ten inches in that direction, and maybe move the mic about 10" to the left if there's anything close to it now..

        Make sure that no speakers on your laptop are playing the sweep. Easy way is to disable the speaker, and run a sweep.

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        • #19
          Hi the baffle is the same some of the readings my be from the left speaker this is the right speaker. so I put the speaker on a milk crate a measured to the tweeter and it was excactly the same from the ceiling as it was previously to the floor 7 ft ceilings ha ha . I have a platform that will work using hockey pucks and rough sawn maple within about an inch.. My laptop is down so measurements will be sporatic until monday. thank you again for the help

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          • #20
            Here are the measurements with the speaker about 1/2 way ceiling to floor.and the changes from above the tv is moved and the speaker is in the middle of the room about 4 ft from the microphone. the green line is the woofer pair with the crossover. the blue line is the woofer without the crossover and the red line is the speaker with the crossover.
            Attached Files

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            • #21
              not sure if this matters at all but this is the woofer and tweeter with the crossover gated measured at 1/4" from the dust cap. does this measurement have any value in assessing the crossover?
              Attached Files

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              • #22
                Originally posted by top gnome View Post
                Here are the measurements with the speaker about 1/2 way ceiling to floor.and the changes from above the tv is moved and the speaker is in the middle of the room about 4 ft from the microphone. the green line is the woofer pair with the crossover. the blue line is the woofer without the crossover and the red line is the speaker with the crossover.
                Looks better. Here's how to improve it a little bit more. (Using these measurements, not new ones.)

                Change the graph to range from -5 to -100, or thereabouts. I like what I can see of the green line. (Or you can move all the response up about 40dB on the chart.)
                BSC looks perfect. Your ears can tell you if you prefer a little more, or a little less.

                Crop out the response below 70hz,or so. This stretches the graph side to side a little, and bass is not accurate here anyway.

                Move the gating to 300hz, maybe lower to 250hz if it stays smooth. You will see a change in response when the reflections start adding in.

                Change the impulse response scale from distance, to time. This doesn't change accuracy, but most here are used to the time scale.

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                • #23
                  Originally posted by top gnome View Post
                  not sure if this matters at all but this is the woofer and tweeter with the crossover gated measured at 1/4" from the dust cap. does this measurement have any value in assessing the crossover?
                  Not really any value I can think of.

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                  • #24
                    Thank you RPB

                    Here are the graphs with the recommended changes.
                    Attached Files

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                    • #25
                      I didn't expect to see ripples at a 300hz gate setting. How loud are your sweeps? Are they loud enough to need ear protection, or be annoying without it? I don't see the noise floor on the green sweep, which makes me think you might be sweeping at a rather high spl. That shouldn't change much, but lower spl sweeps are OK too. (Most of the time.)

                      Did you confirm that nothing other than the speaker that you are measuring is making noise during the sweep? One time at a friends house, his laptop speaker was singing along with the speaker. We didn't find the problem right away, because it was not as loud, but it was close to the mic. Could the other speaker be getting the sweep signal too?

                      Do you have any other speakers to run a sweep on? It might be that 300hz just isn't going to work in your setup. Do things smooth out much at 350hz gate?

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                      • #26
                        I hope I'm not annoying you with so many questions. Your measurements look usable already. They will need a slight interpretation to overlook the ripples caused by reflections. It's just more fun when you get cleaner results.

                        Can you post a picture of the mic, and what's holding it. Is there any chance that there are reflections from the stand clamps?

                        I have my mic strapped to a golf club shaft. I hold it by hand at the grip end. Not much there to cause a reflection.

                        If you measure the tweeter, (with, or without x-over.), from about 24", does the top end smooth out, or change much? Taking a measurement from 2' lets you gate lower.
                        If you measure the tweeter from about 15 degrees off axis, does it smooth out?

                        If you reverse the tweeter polarity, do you get a deep null at the x-over point?

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                        • #27
                          here is the same graph at 400 and where holms autodetects for each . the sweeps are not loud kind of standard listening maybe 70 -80 db volume. the other speaker and the laptop speakers are off. i have some old BA a-40 bookshelf speakers I could try or a pair of super zeros or markentrapazoid 10.3 full range.

                          i just saw your post before the last post I will get some pictures and measurements
                          Attached Files

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                          • #28
                            the mic is taped to a camera tripod here are the reading with the tweeter no cross and at apprx 30 degrees the ripples remain here is in phase (null) and out of phase . and some pics of the setup.

                            there is a slight hum from the other speaker my amp is in the shop and I am using a marantz 1060 so no balanced cables and 50 year old caps.
                            Attached Files

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                            • #29
                              What does the front side of the tripod look like? Wide flat surface? If you are curious enough, you could hold the mic by hand at arms length, and see if anything changes. That would tell you for sure, I think. Anyway, looks like you are in good shape. Good reverse null, and flat response.

                              You could place some felt, foam, or maybe a thick sock on the front side of the tripod. I bet it measures better if you do!


                              Last edited by rpb; 01-19-2020, 12:07 PM.

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                              • #30
                                thank you rpb

                                the tripod is open legged. your responses look very flat that is what I was hoping for I dont think the ripples in the treble are always there they are not nearly as pronoumced in earlier measurements. . I think my room is the culprit. but I am somewhat suspect of the amp. My primare should be back in a couple of weeks. I know the dip at 7k is the baffle edge diffraction adding felt will flatten that out. I also wonder if the Jenga setup the speaker is on may not be contributing - a warped pc of maple and 4 hockey pucks. thank you all again for your help.

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