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Multiple driver speaker testing

Moonlight425

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Sep 6, 2024
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Hello All
I dove into REW and it is super informative. I recently moved a pair of DCM Time Frame 2000s into a small apartment and was determined to make the sound better. Without a real grasp of how phase changes occur I'm having a hard time understanding my graphs. A deep notch around 80 hz caught my eye. I moved the speaker outside on my 2nd story deck 3 feet from a sparse rail. Nothing behind mic or above speaker. Same deep notch and weird to me phasing. SPL was set at 80 for mic test. Proceed HPA-2 amp, Lexicon MC-8 in 2 channel analog bypass. Much more distortion than right speaker which I have yet to move outside. Even inside measured from my normal spot the right is plainly working better. I can hear nothing and would have never suspected any issues. Never go to the doctor when you feel ok ;)
I could use help analyzing what is possibly going on. Not many 2000s around and I LOVE mine. The thought of taking out 24 screws on the back panel of a two transmission line speaker (terminate on front) is daunting and I am a skilled tech. Anyone who would like to look at some REW files or help me with this would be much appreciated.

Thanks!
 
I can't really picture your deck but if there are parallel walls you can get a standing wave in-between. If it's the same dimension as inside, that MIGHT be the same 80Hz standing wave node.

If it's more of an open space measurement it has to be the speaker itself.

I'm not sure what you're seeing with "phasing". Phase is normally only a problem when you have two waves at the same frequency that are not in-phase with each other. You can get in-phase and out-of-phase direct and reflected waves (more standing wave nodes & anti-nodes at different places in the room and at different frequencies). Or, you can get phase cancelation at the speaker's crossover frequencies if the crossover isn't made right (that's probably higher than 80Hz). Or things can get really fouled-up if the phase/polarity of one speaker is reversed.

... It turns-out that notches/dips are not usually as annoying as resonances/bumps.
 
Welcome to ASR! We can help interpret your graphs. Post some graphs along with details of your room dimensions, or better yet post the REW .mdat.
 
Hi and thanks for the warm welcome! DVDDoug, no walls outside other than house well behind speaker. Hi Keith I have tried to down load my REW files with no luck. When I use the attach file here my REW files are no where to be found but file explorer sees it outside this forum. I attached a manual for the TFs so people can get a understanding of how far everything is on this large speaker. I will take a few pics of the data for now and try to post them. Again thanks to all!
 

Attachments

Testl20-600.jpg
Testl70-100.jpg
Testl20-20000.jpg
 
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