Ok so I finished the initial setup of my plan and everything is looking pretty good except for an unexplained 15db hole from 160-210hz in the woofer.
My final setup ended up being:
- iPad > 3.5mm to RCA Cable > MiniDSP 2x4 > tweeter outs to Pioneer vsx-72txv, woofer outs to Pioneer vsx-82txs > speakers & sub.
- The two pioneer AVRs I was able to pick up for $70 each on craiglist, and they have been tested by Sound & Vision to reach 170w RMS in stereo with < 0.1% THD, so they're pretty heavy duty amps, each weighing 40 lbs. I had to cut a hole in the back of my credenza to fit them in because they are so long.
- A bonus of the AVRs being the same brand is that my logitech harmony universal remote treats them as the same device, turning them on and adjusting volume simultaneously.
- The woofer AVR (vsx-82txs) uses its internal bass management (crossover is 12db/oct) to split the woofer and subwoofer signals at 100hz.
- My sub is a Boston Acoustics VR2000, 12" driver & 350w amp that I picked up for $100 on craigslist.
- The MiniDSP uses a 24db/oct LR crossover at 2.3khz as suggested by Jack. I used the MiniDSP's time delay function to phase align the drivers and you can see at 2.3khz the response is very flat
. - I used REW to automatically calculate the biquads to EQ each driver individually and then for the overall speaker.
- My room is 27'x20' with 10' ceilings. It has two large, 10ft wide openings to other rooms. So it's nominally 5500 cuft but sonically larger with the huge openings.
This hole also shows up when I test the woofer by itself. The pink line below shows the Boston VR2000 subwoofer, and the purple line shows the m60 woofer, both measured by themselves at MLP after bass management was applied by the AVR.
Jack do you know if this was a known issue with this driver? Or is there something defective with my unit?
At 180hz, it seems unlikely to me that this is an issue with the subwoofer crossover.
Also I thought at first that it might be a room mode, but given my room dimensions, online calculators show a schroeder frequency of only 125hz, and the last major room node occurring at 150hz. Further, with two huge 10' wide openings to other large rooms, the actual schroeder frequency of my room is probably lower. So too low for a room node to be the cause of the 180hz dip. https://amcoustics.com/tools/amroc?l=27.4&w=20.3&h=9.89&ft=true&r60=0.6
Is it possible that because I didn't install the rubber feet on the speakers that they are sliding back and forth on the credenza with a resonant frequency at 180hz?
This hole is really bothering me so any help would be hugely appreciated!!
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Floor bounce?
http://tripp.com.au/sbir.htm
Try a close mic ( <1cm) measurement of the woofer, it'll tell you if it is room related or a defect with driver ( results are not valid for 300hz and up this way, but at 180hz it should be ok).
http://tripp.com.au/sbir.htm
Try a close mic ( <1cm) measurement of the woofer, it'll tell you if it is room related or a defect with driver ( results are not valid for 300hz and up this way, but at 180hz it should be ok).
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Oh interesting. The speakers are sitting on a credenza with about 8" of the credenza in front of the speakers. I had initially done a back of the envelope calculation of the path difference between sound bouncing off of the credenza vs direct sound. I estimated the path length difference to be around 10", which I thought would mean sound at a wavelength of 20" (675hz) would have a null.
But this calculator you linked seems to suggest much lower frequencies for nulls. I'll try moving the speakers to the edge of the credenza and remeasuring.
Thank you!
It's ceiling bounce!! I just redid the calculator with accurate measurements and I get a ceiling null right at 177hz. Also I tried moving the speakers to the edge of the credenza and also lifting them up by 5" and neither made any major impact.
Since adding diffusion or absorption to the ceiling is not an option my room I guess I can say these speakers are about as good as the room will allow them to be!
Thank you Krivium!
Since adding diffusion or absorption to the ceiling is not an option my room I guess I can say these speakers are about as good as the room will allow them to be!
Thank you Krivium!
The first step in looking at any speaker system, is to take nearfield measurements of the individual driver outputs. This tells you what the driver is doing and removes almost all of the room acoustics effects and some of the cabinet affects. Doing anything else first is a waste of time.
NHT has suffered from the same problem that all other loudspeaker companies have for the last 20 years. The continuing decline in the price of TVs and decrease in their thickness. When huge, thin TVs only cost $300, the vast majority of people will never spend more than $400 on the speaker system. The other related problem is the proliferation of the "smart phone". When most people listen to the 800Hz bandwidth from a phone and think that the audio sounds fine, why would they pay more for a much larger, more expensive product?
NHT has suffered from the same problem that all other loudspeaker companies have for the last 20 years. The continuing decline in the price of TVs and decrease in their thickness. When huge, thin TVs only cost $300, the vast majority of people will never spend more than $400 on the speaker system. The other related problem is the proliferation of the "smart phone". When most people listen to the 800Hz bandwidth from a phone and think that the audio sounds fine, why would they pay more for a much larger, more expensive product?
Hi! I am a proud owner of M60s & XDA. I love these speakers. I have desperately been looking for a s-80 with no luck!
Today I was offered 2 XdW subwoofers, a situation sort of opposite to what a member "homemade" had back in 2010 in this same thread.
I realize I cannot use the Same M60 filters to output to the XdW, since they would be optimized for the s-80, right?
I think the easiest ( laziest) option would be to take the output from the Xda and process it further with a DSP box of choice. However I have failed to find measurements of the XdW subwoofers. S-80 measurements and crossover info can be found in this thread, so I believe somebody has done it same for Xdw, surely! Atleast I hope so.
Do you think there is any point in purchasing these 2?
Oh, and if somebody is willing to part with their s-80, let me know! =-) mail: nemo.mannermaa@outlook.com
Thank you very much in advance!
Nemo
Today I was offered 2 XdW subwoofers, a situation sort of opposite to what a member "homemade" had back in 2010 in this same thread.
I realize I cannot use the Same M60 filters to output to the XdW, since they would be optimized for the s-80, right?
I think the easiest ( laziest) option would be to take the output from the Xda and process it further with a DSP box of choice. However I have failed to find measurements of the XdW subwoofers. S-80 measurements and crossover info can be found in this thread, so I believe somebody has done it same for Xdw, surely! Atleast I hope so.
Do you think there is any point in purchasing these 2?
Oh, and if somebody is willing to part with their s-80, let me know! =-) mail: nemo.mannermaa@outlook.com
Thank you very much in advance!
Nemo
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