Datasat RS20i BETA test and comparison with ADA Rhapsody/Trinnov TEQ-12!!!! - Page 3

OK, a little about measurement systems;

1.) that ruler-flat line that everyone strives for- sorry, it doesn't exist. What you want is a smooth transition from octave-to-octave, frequency-to-frequency. If you look closely at the FR traces (spectrum) you will notice that the horizontal lines are 1db increments. Inspecting the midbass range, you'll see that there are adjustments of roughly 8 db (that's substantially less energy in that frequency range). Again, you can't look at the trace and say "oh my, look at the swings from freq to freq" because that will always be there- you cannot eliminate them. You look at a trace and interpret what the trends are: midbass area is bloated by 6-7db, upper-treble (10k+) is depressed by 4-5 db, then you try to solve for those with as few, wideband/minimum phase filters as possible.

2.) In the first screenshot I posted, the middle section of the screen shows phase response (referenced to the actual source signal) measured by the microphone. You'll notice that from 31-16khz the phase response POST-Dirac remains within +/- 150 degrees and stays pretty smooth, but the phase response without Dirac is greater than +/- 180 degrees; in some cases 360 degrees (delayed)- and that shows that the Dirac processing is in fact reducing the group delay by roughly 25%. I posted earlier that frequency response didn't tell the whole story, here is another significant part of the story.

3.) The result is that Dirac actually makes these 2 speakers sound better than they have any right to in this particular setup- being 5 feet apart setting on a table. The result of the Dirac optimization was that the image became much more 3 dimensional, the bass became tighter (expected, since the midbass bloat was gone), and there was greater resolution brought out of the recordings (upper frequencies being compensated).

The FR traces that I posted were smoothed to 1/12 octave from the normal 1/48 octave I measure at- in order to show the transitions a little better. Essentially, what happens at 1/48 is that the trace from roughly 1k up looks like a richter scale trace, and you're doing a visual average- or you tell the software to average the instantaneous readings (what I do typically- either 1 second averages, or choose the slow response average setting).

I've never used Audessey, I cannot comment on it. Generally, I use commercial DSPs or loudspeaker management boxes and measure like I have here.

Please realize that I didn't post everything I measured- this is not the thick of this experiment, not by a long shot. What I've posted today is the beginning- a glimpse of what it is that Dirac does- for real, not smoothed to 1/3 or 1/2 octave. Our brains do a tremendous amount of averaging when we listen- the microphone and software show us what is really being played, our brains tell us the story.

In any event, the rig I used today was as follows (and will remain the same throughout the experiment) Macbook Pro (2011 model w/ dual core i5 processor), Presonus Firebox (Firewire 800 connection), Earthworks M23 Microphone, Manfrotto mic stand, various 1/4", XLR, combo cables, SMAART v7.(x) - this is in flux, I may upgrade to the latest version (7.3 or 7.4) before the Trinnov shows up. This is a similar rig to what is used to certify live venues, auditoriums, theaters, etc. It's what is used by most professionals and accepted as a reliable measurement system by pretty much all acoustic consultants.

Thanks for reading, I hope everyone else finds this as interesting as I do.

Dan

Noah, yes the bass is 6 db lower, but the speaker uses a 150mm woofer/mid and a 25mm soft dome tweeter. These are near field monitors that really have to be coupled to a subwoofer for true "full range" performance. Basically, this speaker with a different cabinet : http://www.atcloudspeakers.co.uk/scm20aslpro.php

Roger,

Dirac requires 9 measurements for an optimization- I did 15 from directly behind the seat and around, as well as in the seat. Measurements are weighted by multiples (3-4 in the seat, 3 behind, the rest in random locations around). SMAART measurements were taken from behind the seat; the microphone was not ever moved, Dirac was either engaged or disengaged for the measurements.

For the SMAART measurements, I didn't care about the results per-se, but rather the DIFFERENCES between the results. I wanted to see what Dirac was doing, or could make the speaker do. My idea was that the contrast between the Dirac on and Dirac off measurements would give me an idea of what Dirac does that's different from what's available inside a Pre-Pro (the Datasat includes 1/3 octave graphic and 3 parametric bands outside the Dirac capabilities).

Dan

How about this? I zoom the vertical scale out so that it more closely matches the horizontal scale (one db/ 1 hz). You see that the trace becomes extremely flat at that point. Now if I were to smooth this particular curve to say 1/6 octave or 1/3 octave, it approximates a flat line. In reality the speaker is playing flat to about 45 hz where the highpass filter kicks in.

There is no tolerance that you specify, what Dirac does inside the software, I don't know.

I cannot, at the moment screen capture the target curve and post it: I need to be connected to the RS20i in order to fire up the software. (also need a security dongle)

Dirac will eq as low as you tell it to, for better or worse, so if you break something- it's your own fault. "you can send LFE signal to tweeters if you want to"

Hopefully, this clears up your confusion.

Dan

BTW, I was informed yesterday by ADA that the TEQ will be on its way shortly...

 

Post Dirac different scale trace.pdf 164.162109375k . file

6db depression referenced to what? where is point A that point B (<250) is down 6 db?

I'm not following what you're talking about. Please be specific with trace name and locations- it will help me see what you're seeing.

Dan

Noah,

I've looked more closely at the trace where you've pointed out the discrepancy, and to answer the question of whether I find that acceptable or not: NO, I do not. However, I should stress that I wasn't looking at those types of things just yet- the trace had remained relatively flat, the midbass bloat was gone, and the phase response looked substantially better. I didn't mess with the target curve at all- this was just a series of measurements to help me formulate my plan for doing this when things get real (16 channels in the theater, then switch to the Trinnov's 12 channels). Essentially, this test was the "does everything work?" test, further in-depth shakedowns and evaluations are to follow.

I was really looking to see what had happened to the trace when Dirac was enabled, since I've read, like others here, how great it is. My personal hypothesis for my experiment is that I will inevitably find that yes, I will be able to approximate the performance of the Trinnov and the Dirac via Datasat through the use of either built-in tools (Parametric eq, etc) or commercially available DSP. But how long would that take vs the "automated" route?

I have more testing to do this week anyway- I'll play with the target curve and see if the results change at all.

It's entirely possible that this depression has to do with the integral 75mm soft dome in the woofer- that was causing some issues initially with my Dirac process. I've since worked-it-out, but it had me questioning things initially. It appears that Dirac measures similarly to EASERA- impulse response, then everything else is derived from that.

Roger, I was talking about things like a parametric eq, or graphic, or whatever- most manufacturers seem to be including better tools lately, anyway.

I firmly believe that there is no "magic bullet" solution for this; every tool has limitations and drawbacks. My intention is to find those limitations and drawbacks for both the Datasat and the TEQ. What I find most funny is that the home industry seems to be just getting its stride regarding these tools, yet the pro world has had them for years. Of course, it's substantially more difficult to get great results in home theater because small room acoustics seem to magnify anomalies.

Dan

I had a great conference call with Curt Hoyt from Trinnov today. We spent about 3 hours going over the Trinnov process, user interface, and what my workflow will be when the TEQ-12 shows up. This certainly appears to be a very powerful tool; not just in the realm of "room optimization", but as a measurement system as well. You get a tremendous amount of information from this device, and you get the freedom to make whatever adjustments you'd like regarding that specific measurement.

I'm excited to try it. What I'm not excited about is switching between the Datasat and the TEQ- that's going to be interesting! I'm thinking a couple Whirlwind multichannel snakes are the ticket.

Dan

Trinnov is here!!!!

Showed up a couple hours ago. Now the real fun can begin!

Pictures upon un-box.

This is going to be very enlightening...


Dan

Quickie Ttrinnov pictures

A couple more:












Dan

Interesting screenshot, Amir. I'd like to see what that looks like measured with something NOT labeled "JBL Synthesis". Unfortunately, there's no indication of what that resolution is, nor is there an indication of the smoothing. It's an excellent response, to be sure, but what I'm trying to do here is utilize third-party tools to verify what the various parties involved in my experiment are "claiming".

What was the distance from the mic to the loudspeaker? Arrival time of 35.6ms leads me to guess that the measurement distance was in the neighborhood of 20-something feet (I'm assuming roughly 10 ms latency for the DSP). There are swings in that trace (pre-) of more than 10db in the low end, and a midbass depression of 4-5 db spanning almost the entire octave of 500-1k; 'guessing the highpass crossover is in the 600 hz range. That pre-calibration trace isn't quite as rosy at it appears at first glance, and certainly the JBL hardware does a neat job of cleaning the FR. I'd really like to measure with independent hardware to see the real power/accuracy of what the ARCOS system does. Although Synthesis hasn't appealed to me from the "sound" aspect; their technology has fascinated me for quite some time! Of course, it doesn't hurt to have the resources of the "mother ship" to play with.

Very enlightening; we should swap info (traces, methods, etc.) offline so as not to "gum-up" the thread.

Dan

PS-

Thanks for quoting that line that reads like I'll correct high frequency anomalies with wide bandwidth, minimum phase filters; I apparently didn't read that back carefully enough. In reality, I try to leave the midrange/tweeter sections of a loudspeaker as uncorrected as I possibly can- precisely for the reason you mention- 9 times out of 10 what you see is what you can expect from the drivers at hand. I don't mind being more liberal with filters in the lower registers (given of course that the phase response stays in line as well), but the more you futz with the upper-end, the more damage you could potentially do.

I guess the comment to be made is: less is more.