measurements for USB and MT122 |
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psytron
Registered User Joined: 13 July 2007 Location: Australia Status: Offline Points: 172 |
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Posted: 24 August 2009 at 8:20am |
usb was standing up and the mt122 was on top standing up.
I like ur diagram orange beret and those dips are still a mystery to me.... will have a go at 2x usb with a mt122 on top and see what happens ;) |
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orangeberet
Registered User Joined: 11 August 2009 Location: Córdoba (Spain) Status: Offline Points: 32 |
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Really nice job! The cancellation is not posible with the floor, because they will give you different values for the mids and the sub, because of the different distance to the ground, I think. Here you can see an example of cancellation, I don't know the height of the speakers and the mic, so I have written 1,7 m. |
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harold
Registered User Joined: 13 December 2008 Status: Offline Points: 37 |
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IS this with a horizontal mt122?? And do you have picture??
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psytron
Registered User Joined: 13 July 2007 Location: Australia Status: Offline Points: 172 |
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Thanks for the comments Davey T the USB is a nice box :)
I used the behringer emc8000 mic. I am unsure as to wether the dips around 150hz are from phase issues between USB and the mids in the MT122. my reasoning is such ..... -The dips and peaks occur in BOTH the USB and MT122 even when the other is not playing (see chart below) -I have set the delays and the minimum troughs are associated with a setting of USB = )ms SN12b in MT122 = 4.80ms (1.65m) and the cp750ti from the MT122 = 5.68ms (1.950m). these delays were not found using the method you describe (although i like you method) they were found using the berry's auto eq to get an estimate then adjusting for the minimum peaks/troughs. here is a graph of the USB and the SN12b from the MT122 both were recorded independantly and the graphs overlayed but the spl level is obviously wrong (uncalibrated). Note the shapes of the dips are very similar from about 120hz to 160hz is this the Floor or something ??? here are my crossover settings USB hp 50hz 48db but lp 161hz 24db l-r MT122 SN12b hp 124hz 24db l-r lp 1.2khz 24db l-r CP750ti hp 1.2khz 24db l-r does this sound within the realms of being correct??? Edited by psytron - 11 March 2009 at 9:32pm |
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davey t
Young Croc Joined: 11 March 2004 Location: Bristol UK Status: Offline Points: 1428 |
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any pics?!
where abouts in australia are you? I may be heading over to sydney soon :) Edited by davey t - 11 March 2009 at 4:02am |
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Minirig portable soundsystem movement
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davey t
Young Croc Joined: 11 March 2004 Location: Bristol UK Status: Offline Points: 1428 |
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nice work!
now that you have the program and mic etc. you can phase up your system properly and may find that the dip at 150hz will go away (i presume this is where you are crossing over). place the mic 1 to 2m away from the stack in line with the bottom of the mt122/ top of usb. Put zero delay on both mids and usb. Invert the mids polarity and start scrolling up the delay. You should start seeing a dip forming at the crossover point. find the delay with maximum dip then un-invert the mids - hey presto they're in phase. Do the same with the tops and you will find them sounding a lot nicer. Edited by davey t - 11 March 2009 at 4:04am |
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Minirig portable soundsystem movement
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psytron
Registered User Joined: 13 July 2007 Location: Australia Status: Offline Points: 172 |
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after setting the crossover points and a bit of fiddling with some eqs and delay this is what i came up with...
here it again smoothed to 1/3 octave Any questions or suggestions are most welcome :) enjoy |
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psytron
Registered User Joined: 13 July 2007 Location: Australia Status: Offline Points: 172 |
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As you can see there are some peaks and troughs around 150hz for both the mids and the usb i believe this to be an artifact of the location (reflections etc) and probably not caused bu the speaker/box combination.
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psytron
Registered User Joined: 13 July 2007 Location: Australia Status: Offline Points: 172 |
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cp750ti crossed at 1.2khz no eq
cp750ti as above smoothed |
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psytron
Registered User Joined: 13 July 2007 Location: Australia Status: Offline Points: 172 |
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Mids SN12B no eq, crossover, nor eq.
sn12b as above smoothed |
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psytron
Registered User Joined: 13 July 2007 Location: Australia Status: Offline Points: 172 |
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smooth = 1/3rd octave for all images that are smoothed.
oh and db reading are not calibrated to exact db so use graphs relatively :) --------------------------------------------------------- USB no eq, crossover, nor filters USB no eq, crossover, filters but smoothed Edited by psytron - 11 March 2009 at 12:15am |
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psytron
Registered User Joined: 13 July 2007 Location: Australia Status: Offline Points: 172 |
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hello hello :)
Well i have finally taken some measurements of my system via "Room EQ Wizzard" -( great free prog ) details of system under test ------------- 1x USB Definimax loaded (standing upright/tall) 1x MT122 sn12b and cp750ti loaded (upright ontop of usb) USB powered by 1 channel of ca-20 (sound standard) MT122 phonic 2500 for sn12b's (2 in ll from one channel (4ohm total)) phonic 1500 for cp750ti ultradrive for processing Measurement devices ----------------- emc8000 mic Eurorack ub1002 for mic phantom and preamp duties crappy usb soundcard calibrated via loopback in software. Mic was on a stand level with and pointing at the comp horn about 5m away on axis. situation a back yard with scattered trees behind mic (2-3m behind) level grass floor, with a wood/brick house +5m behind stack not directly on axis (15deg off??? ) graphs to come... |
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