My initial goal with this setup was to get it working nicely on a totally passive XO, and if you think about it, this is an incredibly powerful and efficient speaker system that could be run off any receiver or 100 watt amp and hit well over 110db or more. It's a very modular setup and very easy to set up and take down.
Next step was to make it fully active, which I did today. By going active I hoped to time align the horns, play with various XO slopes and flatten the frequency response.
I'm using an OpenDRC DA8 from miniDSP
If you're interested in this unit it's really nice for the $355 price, the only catch is it only has a digital coax input, which I was able to use an optical output on my Mac headphone jack and I used a simple converter to go from optical to coax.
An Adcom GFA-555II runs the 4 PA460, and a 4 channel Adcom GFA-2535 running each pair of horns.
XO slopes I've been playing with but are currently 48db between the high and midbass horns and 24db between the subs and midbasss. I ended up with 3-4 filters on each channel, quite minimal considering the flat response.
I ended up with 1.7ms of delay on the high freq horns, switching it on and off in hard pressed to hear a big difference, but it is slightly noticeable. I've played with time alignment a number of times and I'm led to believe a lot of people make a bigger deal of its importance than is reality.
All measurements are nearfield at one meter centered on the Seos24
Basic setup in minidsp
The PEQ filters on the high freq horn
Individual driver response and combined
Comparison to the passive setup, (disclaimer,I could have spent more time on the passive setup to improve the response no doubt), also note a subsonic filter at 30hz
Distortion is very low, less than 1% above 100 at 100db, less than 9% down to 20hz
Overall this configuration does sound better, it's more coherent and the flat freq response sounds better. Bass measures quite hot nearfield but is only about 3db hot in the listening position, plus I like bass .
If I haven't said this already, listening to powerful and dynamic music on these is a totally immersive experience, I find myself pausing the music to catch my breath at times, heart racing. They easily produce full spectrum response at 115db including bass, the entire house shakes and the walls rattle from the inside. Despite this the dual opposed configuration is vibration free, the horns never move a nanometer. I haven't stressed or maxed out the subs yet, with only "6mm" xmax these $95 subwoofers astound, with this much cone area bass is accurate and effortless. I really wish you could all come over and hear these =)
Thanks!
Javad
Next step was to make it fully active, which I did today. By going active I hoped to time align the horns, play with various XO slopes and flatten the frequency response.
I'm using an OpenDRC DA8 from miniDSP
If you're interested in this unit it's really nice for the $355 price, the only catch is it only has a digital coax input, which I was able to use an optical output on my Mac headphone jack and I used a simple converter to go from optical to coax.
An Adcom GFA-555II runs the 4 PA460, and a 4 channel Adcom GFA-2535 running each pair of horns.
XO slopes I've been playing with but are currently 48db between the high and midbass horns and 24db between the subs and midbasss. I ended up with 3-4 filters on each channel, quite minimal considering the flat response.
I ended up with 1.7ms of delay on the high freq horns, switching it on and off in hard pressed to hear a big difference, but it is slightly noticeable. I've played with time alignment a number of times and I'm led to believe a lot of people make a bigger deal of its importance than is reality.
All measurements are nearfield at one meter centered on the Seos24
Basic setup in minidsp
The PEQ filters on the high freq horn
Individual driver response and combined
Comparison to the passive setup, (disclaimer,I could have spent more time on the passive setup to improve the response no doubt), also note a subsonic filter at 30hz
Distortion is very low, less than 1% above 100 at 100db, less than 9% down to 20hz
Overall this configuration does sound better, it's more coherent and the flat freq response sounds better. Bass measures quite hot nearfield but is only about 3db hot in the listening position, plus I like bass .
If I haven't said this already, listening to powerful and dynamic music on these is a totally immersive experience, I find myself pausing the music to catch my breath at times, heart racing. They easily produce full spectrum response at 115db including bass, the entire house shakes and the walls rattle from the inside. Despite this the dual opposed configuration is vibration free, the horns never move a nanometer. I haven't stressed or maxed out the subs yet, with only "6mm" xmax these $95 subwoofers astound, with this much cone area bass is accurate and effortless. I really wish you could all come over and hear these =)
Thanks!
Javad
How is phase curve passive versus active? I believe that four ported 18" no matter what they cost is enough for normal use
JShadzi, please show a measurement from listening spot, L/R speakers separately. Then we would see what your room makes for mass. Your nearfield shows 10dB difference between 35/50Hz. It would be very easy to eq bass response more flat - jus attenuate 50-60Hz region and do moderate boost around 30Hz (what is actual tuning frequency?) You must leave some dips/bumps in response at room modes!
How did you check for delays? I look at step response very closely 0-6ms after first peak. By switching one section off at a time you can see which peak comes from each section. Polarity of peaks alters the visual appearance of total step curve and many times polarities differ as per xo configuration.
How did you check for delays? I look at step response very closely 0-6ms after first peak. By switching one section off at a time you can see which peak comes from each section. Polarity of peaks alters the visual appearance of total step curve and many times polarities differ as per xo configuration.
Great project. Has there been any updates?
As far as time alignment goes, one can wonder if it is a big deal at all - until one studies how the ear/brain/hearing works. Then we realize that we have no choice but to align. The problem is, with a 2 or 3 way system, we reach mechanical limits for each of the drivers and are forced to use sharp slopes - that introduce garbage that masks phase response. Maybe a question of picking your poison. You could try turning the subwoofers 90° and remeasuring. You are closer to alignment with the midbass horn and getting all 4 woofers equidistant from your ears.
It is a big deal and could take many systems to another level. Like any change, we need time to adapt and once acclimated never go back.
As far as time alignment goes, one can wonder if it is a big deal at all - until one studies how the ear/brain/hearing works. Then we realize that we have no choice but to align. The problem is, with a 2 or 3 way system, we reach mechanical limits for each of the drivers and are forced to use sharp slopes - that introduce garbage that masks phase response. Maybe a question of picking your poison. You could try turning the subwoofers 90° and remeasuring. You are closer to alignment with the midbass horn and getting all 4 woofers equidistant from your ears.
It is a big deal and could take many systems to another level. Like any change, we need time to adapt and once acclimated never go back.
hey Javad - if you don't already have - pick up a copy of this CD - its more tonally tuned to the toms than snare but still one of the best (you will thank me - i think)
Amazon.com: Buying Choices: Solo Drums
Amazon.com: Buying Choices: Solo Drums
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