TerryC
Stunt Coordinator
- Joined
- Oct 19, 1999
- Messages
- 218
I posted this in the Hometheater Hardware forum but the Dual Mass results will probably be of interest in this DIY section as well.
I finally got around to the Mass/Velo comparison with the help of Rich and all I have to say is, oh my god! I'm a measurement kind of guy so I'll cut to the chase and present the info.
Velo is a standard FSR-15 .(BTW this sub currently is currently in the number five spot for measured bass performance by the master of bass Tom Nousiane) See more of his comparisons here.
Dual Mass is a DIY that uses Dual 12" Audiomoible Mass 2012 drivers in a 11ft3(11 cubic foot enclosure) with its ports tuned way down to 17hz. Subs were switched out and placed in the same location for all tests. These are very close ralatives to the Aerial SW12 Drivers but instead of 15mm of each way travel they have 19mm! See more of the Aerial here.
Processor used was a Meridian 861, FSR15 used its internal amp and the Dual Mass used a Crown K1 that puts out 1400W. No EQ was used but the Meridian was using a 58hz low pass crossover on the sub channel. Mic used was a 150db LinearX M51 and software was SpectraPlus. Testing room is about 7500-8000ft3.
Here is a pic of the cast of characters along with one of the Meridian DSP6000 mains that where tuned off for the testing so they wouldn't interfere with the test results. http://terryctheater.tripod.com/velomassmerridian.jpg
On to the test results:
We first decided to use a a semi quite frequency sweep at 1 meter to see how they performed. http://terryctheater.tripod.com/fsrmass1meter.jpg
Red- FSR 15
Pink- Dual Mass
As you can see, both subs performed fairly equal with the exception of the Mass playing lower. There are some small differences at other frequencies which are caused by the different attributes of each sub along with the fact the FSR sits on the floor with one radiating surface while the Dual Mass also has one of its drivers located up top just over 4 feet up!
Here is a balls to the wall Max SPL test taken at the seat 13ft away! http://terryctheater.tripod.com/128m...xspseatedl.jpg
Red-Dual Mass
Green-FSR15
As you can see this is where it gets really interesting.
(I'll explain an interesting tidbit for those that don't know how sub specs are accomplish after the next graph to help explain it.)
As you can see at loud levels the Dual Mass is still relatively the same as when it was tested at a lower volume but the FSR is way different as it starts to role off the bottom end. In this test the Dual Mass absolutely annihilates the FSR15! Its about 20dB louder at 20hz!!! That's one heck of a difference and I was shocked to be honest I was thinking it would be about 6db to 10db. You can clearly see the FSR's limiters preventing the speaker from trying to produce frequencies at volumes it can't. This is a real eye opener at just how much the velo sub does this!
Here is the limiter at work on the Velo taken at 1 meter: http://terryctheater.tripod.com/fsrlimiter.jpg
Red-Velo 1 meter
Pink-Dual Mass 1 meter
Blue-Velo turned up louder 1 meter
Green-Velo tuned up louder 1 meter
In this test we used the first graph that was tested at one meter as a baseline but increased the volume on each of the two subsequent passes to show the limiter in action.
As you can see the velo had decent extension at low volume. This is because the speaker is barely moving back and forth so it can produce a all of those frequencies. This is similar to how they spec speakers with 1 watt of power which doesn't even stress the speaker.
Notice when we play it loud the bottom end disappears on the FSR15. This is because the speaker doesn't have the mechanical movement(back and forth movement) it would take to produce these low frequencies. The designers knew this when they made the speaker so they included a limiter which automatically cuts back the volume at those frequencies. This is a good thing as it protects the sub from damage but as you can see it makes a decent spec'd sub not even come near its spec frequency response at loud levels. IMHO they needed to use a better driver so they wouldn't have to do cut the info so early and as you can see in the case of the FSR15 it's about 28hz or so.
That's the end of the testing.
On a side note you will notice a little window in the graphs. This represents the combined reading of all the frequencies the way a Radio Shack meter would show. So for instance even though the mass on the line graph shows a high reading of about 115 to 116db at 53hz area it was actually showing a peak reading of 128.23db at 13 feet away! If you are trying to compare this to a rat shack meter this is the figure to use! Yes we reached 128db! We also did a comparison of how off the rat shack meter is at loud volumes and we did a test where the Rat shack meter read 116.5db and Spectra was showing 122db. I know this compares well with what Tom Vodhanel figured on his mic's as well.
It was a lot of work and I hope some find the information insightful as to just how much a top performing sub can be off at higher volumes. It also shows how much of a killer system DIY can get you.
Terry
I finally got around to the Mass/Velo comparison with the help of Rich and all I have to say is, oh my god! I'm a measurement kind of guy so I'll cut to the chase and present the info.
Velo is a standard FSR-15 .(BTW this sub currently is currently in the number five spot for measured bass performance by the master of bass Tom Nousiane) See more of his comparisons here.
Dual Mass is a DIY that uses Dual 12" Audiomoible Mass 2012 drivers in a 11ft3(11 cubic foot enclosure) with its ports tuned way down to 17hz. Subs were switched out and placed in the same location for all tests. These are very close ralatives to the Aerial SW12 Drivers but instead of 15mm of each way travel they have 19mm! See more of the Aerial here.
Processor used was a Meridian 861, FSR15 used its internal amp and the Dual Mass used a Crown K1 that puts out 1400W. No EQ was used but the Meridian was using a 58hz low pass crossover on the sub channel. Mic used was a 150db LinearX M51 and software was SpectraPlus. Testing room is about 7500-8000ft3.
Here is a pic of the cast of characters along with one of the Meridian DSP6000 mains that where tuned off for the testing so they wouldn't interfere with the test results. http://terryctheater.tripod.com/velomassmerridian.jpg
On to the test results:
We first decided to use a a semi quite frequency sweep at 1 meter to see how they performed. http://terryctheater.tripod.com/fsrmass1meter.jpg
Red- FSR 15
Pink- Dual Mass
As you can see, both subs performed fairly equal with the exception of the Mass playing lower. There are some small differences at other frequencies which are caused by the different attributes of each sub along with the fact the FSR sits on the floor with one radiating surface while the Dual Mass also has one of its drivers located up top just over 4 feet up!
Here is a balls to the wall Max SPL test taken at the seat 13ft away! http://terryctheater.tripod.com/128m...xspseatedl.jpg
Red-Dual Mass
Green-FSR15
As you can see this is where it gets really interesting.
(I'll explain an interesting tidbit for those that don't know how sub specs are accomplish after the next graph to help explain it.)
As you can see at loud levels the Dual Mass is still relatively the same as when it was tested at a lower volume but the FSR is way different as it starts to role off the bottom end. In this test the Dual Mass absolutely annihilates the FSR15! Its about 20dB louder at 20hz!!! That's one heck of a difference and I was shocked to be honest I was thinking it would be about 6db to 10db. You can clearly see the FSR's limiters preventing the speaker from trying to produce frequencies at volumes it can't. This is a real eye opener at just how much the velo sub does this!
Here is the limiter at work on the Velo taken at 1 meter: http://terryctheater.tripod.com/fsrlimiter.jpg
Red-Velo 1 meter
Pink-Dual Mass 1 meter
Blue-Velo turned up louder 1 meter
Green-Velo tuned up louder 1 meter
In this test we used the first graph that was tested at one meter as a baseline but increased the volume on each of the two subsequent passes to show the limiter in action.
As you can see the velo had decent extension at low volume. This is because the speaker is barely moving back and forth so it can produce a all of those frequencies. This is similar to how they spec speakers with 1 watt of power which doesn't even stress the speaker.
Notice when we play it loud the bottom end disappears on the FSR15. This is because the speaker doesn't have the mechanical movement(back and forth movement) it would take to produce these low frequencies. The designers knew this when they made the speaker so they included a limiter which automatically cuts back the volume at those frequencies. This is a good thing as it protects the sub from damage but as you can see it makes a decent spec'd sub not even come near its spec frequency response at loud levels. IMHO they needed to use a better driver so they wouldn't have to do cut the info so early and as you can see in the case of the FSR15 it's about 28hz or so.
That's the end of the testing.
On a side note you will notice a little window in the graphs. This represents the combined reading of all the frequencies the way a Radio Shack meter would show. So for instance even though the mass on the line graph shows a high reading of about 115 to 116db at 53hz area it was actually showing a peak reading of 128.23db at 13 feet away! If you are trying to compare this to a rat shack meter this is the figure to use! Yes we reached 128db! We also did a comparison of how off the rat shack meter is at loud volumes and we did a test where the Rat shack meter read 116.5db and Spectra was showing 122db. I know this compares well with what Tom Vodhanel figured on his mic's as well.
It was a lot of work and I hope some find the information insightful as to just how much a top performing sub can be off at higher volumes. It also shows how much of a killer system DIY can get you.
Terry
