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Multi-Way Conventional loudspeakers with crossovers

Box port or crossover dippity do
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Old 25th October 2019, 03:04 AM   #31
AllenB is offline AllenB  Australia
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Could you post a screen shot of your Holm window with a measurement, with the small dialogue box from the options button next to the measurement, and the impulse showing and zoomed to partially fill the window?
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Old 25th October 2019, 06:57 AM   #32
8ntractor is offline 8ntractor  Canada
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Hi Allen Here is a screen shot I hope I got the info you are looking for thank you. I did switch the speakers right for left and the large dip in the bass on the left speaker is the room. thank you again for your help
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File Type: png Screenshot (4).png (599.1 KB, 82 views)
File Type: png Screenshot (5).png (623.3 KB, 77 views)

Last edited by 8ntractor; 25th October 2019 at 07:26 AM.
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Old 25th October 2019, 08:20 AM   #33
8ntractor is offline 8ntractor  Canada
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Hi allen that is a single woofer
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Old 25th October 2019, 09:52 AM   #34
AllenB is offline AllenB  Australia
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Ok, ...

In the measurement options for the tweeter, below 'raw response', choose 'Impulse time-window (gating)'. This explains why moving around the room makes a difference when it shouldn't.

In the impulse response window, you can only see a flat plot. The vertical is zoomed out. Maybe you could click on auto zoom, then zoom out as required and reverse drag across the plot to zoom back in.

The blue arrow just before 2kHz indicates the lowest frequency that your gating window can resolve, which of course you can change. First though, the start point is -100 (from locked) which includes some empty space, which is counted, so you aren't even actually quite getting 2kHz. You might be able to set it to -20, watch that this doesn't affect the measurement by chopping off the start (make sure the response stays close to the same and that both channels are done. Then you can extend the time by either dragging the right side of the dashed line on the impulse plot or setting in the 'To:' box next to 'auto detect'.

It may or may not be an issue that your measurement came in at over 0dB. Noise gets further away, but distortion gets closer. (Just noticed your offset, ouch, unless something isn't calibrated. Not important though as long as you are within a good operating region.)

Learning where to gate and how successful you were in clearing a space, will be easier to see when you fix the tweeter measurement.
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Old 25th October 2019, 03:05 PM   #35
8ntractor is offline 8ntractor  Canada
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Hi AllenB thank you for taking the time to explain this to me. I reran the tweeter and both woofers I am still running REW for the measurements and need to figure out how to get Holm to do it I have a Primare pre pro and it is pretty old so the usb or hdmi will not work. I am seeing the advantage of the Holm software and there is a learning curve. I am attaching the data but I do not think it can be imported and give accurate results. this is with both woofers no crossover gated and ungated. thank you again for your help. I have finished the audiophile speaker and most of the Weems book. The next thing I am going to do is go back and read your sticky again I read it a few weeks ago but I think I will have a better understanding now. thank you again
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File Type: png Screenshot (7).png (745.5 KB, 59 views)

Last edited by 8ntractor; 25th October 2019 at 03:08 PM.
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Old 26th October 2019, 11:24 AM   #36
AllenB is offline AllenB  Australia
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Ideally, your impulse should be clearly visible, followed by near silence (for several milliseconds).
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Old 26th October 2019, 01:51 PM   #37
8ntractor is offline 8ntractor  Canada
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Thank you Allen that look looks a lot better than my tweeter. I ordered a cable that I think will separate the mic from the headphone jack and let me use the windows computer. I moved the speakers to the best position in the room and they are disappointing. almost ready to start from scratch with more room appropriate sized speakers. The woofer chart looks closer to yours maybe a single woofer would be a better choice. Sending that chart was very helpful now I know what I am looking for thank you. I am working thru your non measurement sticky. and will lay it out when I get the chance. I was stuck on keeping the crossover I have and after listening I am unstuck. thank you again for your help
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File Type: png Screenshot (10).png (706.7 KB, 9 views)
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Old 26th October 2019, 03:11 PM   #38
AllenB is offline AllenB  Australia
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Quote:
Originally Posted by 8ntractor View Post
I ordered a cable that I think will separate the mic from the headphone jack and let me use the windows computer.
I hope it works. IntelHDA (successor to AC'97 audio standard for PCs) allows jack retasking. I can turn my inputs into outputs and like that.
Quote:
maybe a single woofer would be a better choice.
Here's the thing with the dual woofers when in MTM configuration. At tweeter height you get +6dB from any horizontal angle, and the measurement should otherwise look just like a single driver. The dual woofers should narrow vertical directivity for a reduction in ceiling reflection etc. (By the way, reasonable results can be had like any conventional speaker but the proper exploitation of the MTM configuration is much less simple.)
Quote:
I moved the speakers to the best position in the room and they are disappointing. almost ready to start from scratch
Don't be discouraged, it took me a very long time before I could build a speaker I liked.

Regarding sizing a speaker to fit a room. I don't know exactly where this suggestion came from but I know that it doesn't always apply.
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Old 27th October 2019, 06:00 PM   #39
8ntractor is offline 8ntractor  Canada
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Hi AllenB

I had a 6 hour drive yesterday and by the time I got home i was considering putting the corroded mag drivers and crossover parts back in and calling it a day. After reading your message I guess nothing worth doing is easy and i am learning. so thank you for that


Quote:
Here's the thing with the dual woofers when in MTM configuration. At tweeter height you get +6dB from any horizontal angle, and the measurement should otherwise look just like a single driver. The dual woofers should narrow vertical directivity for a reduction in ceiling reflection etc. (By the way, reasonable results can be had like any conventional speaker but the proper exploitation of the MTM configuration is much less simple.)

I think you are saying that the tm may be easier to build than the mtm if I start from scratch? I do not mind building new cabinets. 7 ft ceilings small room. originally l was looking for a direct replacement to keep the thors .But after listening and making the simple changes to the crossover I don't think pulling a couple of components will do it. I think starting from scratch is going to be necessary.

While waiting for the cable to use Holms. I ran thru your procedure on building crossovers and entered it in xsim and a spreadsheet. I used the measured woofers and the sim tweet as that measurement is so bad. looks good. it looks like I cannot load the spreadsheet. the xsim is attached.

I also found a TM madisound design for 2011 using those drivers but the cabinet is only .48 sq ft. not sure if leap is any different than xsim we do not get the same results close though.

thank you again for your help
Attached Images
File Type: jpg Allens cross.jpg (37.0 KB, 16 views)
File Type: jpg Allens fr.jpg (71.7 KB, 12 views)
File Type: jpg Allens imp.jpg (68.5 KB, 9 views)

Last edited by 8ntractor; 27th October 2019 at 06:04 PM.
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Old 27th October 2019, 06:42 PM   #40
8ntractor is offline 8ntractor  Canada
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I know this may be the easy way out but I found this Madisound Tom Roberts TM design from 2011 - I modified it and made small changes to the inductors .3 to .24 and .12 to .15 then I would only have to add 2 capacitors 65 to the woofer and several resistors. the rest of the parts can come from the old crossovers. the charts look pretty good.

Just another option. I think the woofer caps can be of lower quality than the tweeter caps?

Do you normally buy a series or several different resistors and caps to be able to make adjustments?

thank you
Attached Images
File Type: jpg Madisound tm cross.jpg (23.1 KB, 11 views)
File Type: jpg Madisound tm fr.jpg (65.7 KB, 11 views)
File Type: jpg Madisound tm imp.jpg (69.1 KB, 10 views)
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