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Discussion Starter · #1 ·
so, i've just added an SMS-1 to my setup and need a fact-check on what i've done thus far. i'm a relative novice, so the intricacies of PEQ adjustment are a bit of a mystery. i understand what the three adjustments are (freq, boots, width), but how are they best applied? anyway, i...


1) moved sub to my listening position (actually up on the couch).

2) hooked it all up per the velodyne docs.

3) set pre/pro eq to 'off' (not 'flat').

4) played sms test sweeps with sub & mains active, level matched sub with mains as best i could (using sms volume control), moved the mic to the handful of possible locations for the sub (down on the floor), found the flattest 'raw' location.

5) manually eq-ed the sub to be as flat as possible, figuring it would stay that way (mostly) after i switched sub/mic.

6) swapped sub/mic, replayed test tones, checked level matching.

7) manually re-eq-ed the sub to be as flat as possible at the primary listening position, including big 15-20hz boost to get that end up as high as possible (sealed sub doesn't dig ultra deep). surprised to see that the gorgeous flat curve i had with the sub on the couch is not the same with the positions switched?

8) re-ran the audyssey calibration (8pt multieq-xt, position 1 being where i placed the sms mic during eq).

9) looked at sms sweeps again...but changed nothing.


i figure this method allows audyssey to see the eq-corrected sub as a 'virtual' sub, about which it could then gather accurate data and calibrate. as expected, the distance measured to the sub went up a few feet do to the sms dsp delays, and the final sms sweep is no longer flat.


have yet to do any serious listening, but i can say that at first blush, there is definitely more subsonic info, and perhaps more detail overall. i had a big hole at 50hz that is mostly filled (thanks to some serios PEQ slider stacking).


one question. the upper range of the sms adjustability seemed to make no difference. i could jack the 80+hz sliders any which way and make virtually no difference. i guess that's the pre/pro 120hz LFE low-pass? mains are crossed at 60hz.


a few pics:


 

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If you haven't already done so, you might want to check these operating instructions. These are supposed to be better than the manual from Velodyne.


Click on "The Outlaws Guide to the SMS-1", it's a lengthy PDF file.

http://www.outlawaudio.com/products/sms1.html
 

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One thing I notice is how much boost you've applied in an effort to level out the response. Generally you shouldn't boost, especially if you're then running Audyssey after you've applied all that boost. Doing that much boosting, especially the lower end sucks up all your amp's headroom.


You could improve low end response by putting your sub near a corner if possible. You can strike a balance between overall response and low end boost by placing it near a wall or corner.


I would work on getting as good a response as you can by using trims only in the SMS. Then run Audyssey.
 

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Quote:
Originally Posted by dookie1 /forum/post/18160833


so, i've just added an SMS-1 to my setup and need a fact-check on what i've done thus far. i'm a relative novice, so the intricacies of PEQ adjustment are a bit of a mystery. i understand what the three adjustments are (freq, boots, width), but how are they best applied? anyway, i...


1) moved sub to my listening position (actually up on the couch).

2) hooked it all up per the velodyne docs.

3) set pre/pro eq to 'off' (not 'flat').

4) played sms test sweeps with sub & mains active, level matched sub with mains as best i could (using sms volume control), moved the mic to the handful of possible locations for the sub (down on the floor), found the flattest 'raw' location.

5) manually eq-ed the sub to be as flat as possible, figuring it would stay that way (mostly) after i switched sub/mic.

6) swapped sub/mic, replayed test tones, checked level matching.

7) manually re-eq-ed the sub to be as flat as possible at the primary listening position, including big 15-20hz boost to get that end up as high as possible (sealed sub doesn't dig ultra deep). surprised to see that the gorgeous flat curve i had with the sub on the couch is not the same with the positions switched?

8) re-ran the audyssey calibration (8pt multieq-xt, position 1 being where i placed the sms mic during eq).

9) looked at sms sweeps again...but changed nothing.


i figure this method allows audyssey to see the eq-corrected sub as a 'virtual' sub, about which it could then gather accurate data and calibrate. as expected, the distance measured to the sub went up a few feet do to the sms dsp delays, and the final sms sweep is no longer flat.


have yet to do any serious listening, but i can say that at first blush, there is definitely more subsonic info, and perhaps more detail overall. i had a big hole at 50hz that is mostly filled (thanks to some serios PEQ slider stacking).


one question. the upper range of the sms adjustability seemed to make no difference. i could jack the 80+hz sliders any which way and make virtually no difference. i guess that's the pre/pro 120hz LFE low-pass? mains are crossed at 60hz.


a few pics:

I do things in the opposite order. I run Audyssey *first*, then I use the SMS-1 to flatten the resultant response curve further. Let me explain my logic, and you can reconsider your use if you care to:


Audyssey is a multi-point EQ that measures an "area" and attempts to flatten the response over that area. In addition, it attempts to correct in the time domain as well as the frequency domain. The SMS-1 is a single point EQ that can only correct a single listening position and only in the frequency domain.


Therfore, I use Audyssey first to perform it's correction over the listening area. It usually gets the response closer to flat, but not quite totally flat. However, if you look at the time response, it shortens the decay of the bass over all the listening positions considerably. To me, this correction is more important than perfectly flat frequency response. Also, if you perform the SMS-1 single point FR correction first, Audyssey may measure a significantly different response at other LP's and may actually work to *undo* the correction you've added with the SMS-1. By running Audyssey first, you can usually get much smoother FR first, so you need to use less boost/cut on the SMS-1 to get flat response. Finally, you can get flatter response over the entire listening area first, then use the SMS-1 to flatten the response at the most important LP... the sweet spot, (where YOU sit).


For all these reasons, I run Audyssey first, then use the SMS-1 on the resultant curve.


Some other general comments;


I don't like to use more than 3 dB of boost on any single SMS-1 band. 3 dB of boost equals a *doubling* of the power required at that band. Also, if adding boost, I never use a wide Q, as this adds significant power requirements over a wider frequency band. If I'm adding boost at all, it is limited to 3 dB and over no more than 1/3 octave. BTW, nulls, or depressions in the response are much less audible than peaks, and it is less important to *boost* than it is to cut peaks.


I never "stack" filters, especially when adding boost, (see above, which is greatly exacerbated when stacking filters.)


I never use more than 6 dB of cut on any single SMS-1 band. 6 dB of cut equals a 75% reduction of power at that frequency band. I would prefer a few dB of extra SPL at a given frequency band than to neuter the output at that band by so much power. I feel it reduces the impact of the bass by reducing the power so significantly.


Here is what my final response curve looks like using the strategy I employ:




Note the Time/Energy/Frequency graph in the upper right. This shows there is very little ringing and overhang in my room and system, (for the most part, the energy has "stopped" with 100 to 200 ms if when it starts.) This is a product of Audyssey's processing, and of the bass traps and acoustic treatments in my room. IMO, this is more important than the flat FR curve in terms of sound quality.


Anyway, there are many ways to approach this issue. I have presented my logic and technique. You may find it useful and beneficial. Good luck.


Craig


Edit: I forgot to add one important thing: It is important, no matter which order you do this, to have the SMS-1 in the circuit when running Audyssey. The SMS-1 has some inherent delay, (it takes some time to process the signal... there is a A to D conversion, then the digital EQ, then a D to A conversion.) This all takes a little time, (~ 2 ms) that needs to be accounted for in the "Distance" setting set by Audyssey. When I run the two EQ's with Audyssey first, I place the SMS-1 into the circuit, but I set it for flat output, (no EQ applied.) Then I run Audyssey and it always finds the subwoofer distance about 6 ft. further than it's actual physical distance. This adds some delay to the speakers that allows the subwoofer to "catch up", so the waves from the speakers and the waves from the subs arrive at the LP at the same time. Once Audyssey has finished, I *then* use the SMS-1 to flatten the FR further at the LP.
 

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Discussion Starter · #5 ·
thanks...that is extremely helpful. i will try it your way as well and see what it sounds like.


i had read (in the audyssey thread) that making frequency adjustments to the sub after audyssey corrects the time domain can upset those adjustments, which we both agree are more significant that a flat freq. curve.


fun toys to play with!
 

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Quote:
Originally Posted by craig john /forum/post/18172870


Note the Time/Energy/Frequency graph in the upper right. This shows there is very little ringing and overhang in my room and system, (for the most part, the energy has "stopped" with 100 to 200 ms if when it starts.) This is a product of Audyssey's processing, and of the bass traps and acoustic treatments in my room. IMO, this is more important than the flat FR curve in terms of sound quality.

Agreed but can you compare the TEF results before/after the SMS-1 EQ?
 

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Quote:
Originally Posted by Kal Rubinson /forum/post/18174667


Agreed but can you compare the TEF results before/after the SMS-1 EQ?

I have been meaning to do that comparison and post it. I'm out of town right now, (visiting the kids and granddaughter.)
I won't be back home for a few days. I'll try to do that late next week or over the next weekend. I will also try to do the pre- and post-Audyssey to show the time domain improvement from Audyssey.


I know you have this same program, (xtz Room Analyzer), and you have used it, probably more extensively than I. Have you done these same comparisons?


Craig
 

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Quote:
Originally Posted by craig john /forum/post/18174804


I have been meaning to do that comparison and post it. I'm out of town right now, (visiting the kids and granddaughter.)
I won't be back home for a few days. I'll try to do that late next week or over the next weekend. I will also try to do the pre- and post-Audyssey to show the time domain improvement from Audyssey.


I know you have this same program, (xtz Room Analyzer), and you have used it, probably more extensively than I. Have you done these same comparisons?


Craig

I have done it with Audyssey (in various flavors), ARC, Trinnov and a few sub EQs. I have not done it with the SMS-1 with or without one of the others.
 

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Kal, I tried the SMS-1 with Audyssey and didn't like the SQ that I got. Had the same issue with the Anti Mode. However with the same setup, I had excellent results with MCACC. So for now, I'm sticking to pure Audyssey all the way. If I find that I do need sub EQ, then I will go with Audyssey Sub EQ.


Bill
 

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Quote:
Originally Posted by bsoko2 /forum/post/18176066


Kal, I tried the SMS-1 with Audyssey and didn't like the SQ that I got. Had the same issue with the Anti Mode. However with the same setup, I had excellent results with MCACC. So for now, I'm sticking to pure Audyssey all the way. If I find that I do need sub EQ, then I will go with Audyssey Sub EQ.


Bill

I was not advocating any of these combinations. I was just responding to the question.
 

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Discussion Starter · #11 ·
ok...so here's another detail i don't get:


the sms test tone output is 2-channel. audyssey crosses my front mains (def tech bp30) over at 40hz, though i have raised it to 60. the sub (epik empire) offers excellent mid-bass performance.


so with a stereo input and a 60hz crossover, that leaves a whole lot of sub range that the sms never sees, and therefore can't eq. how should i handle this? move the main crossover much higher? just for the sms dial in? permanently? run 'all channel' stereo, so that the sms sees some mid bass signal from the surrounds (crossed over at 100-120hz)?


thx.
 

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If you want to have the SMS-1 "see" the mid-bass, you'll need to raise the crossover. 80 Hz is a good starting point. It you raise it and EQ up to 80 Hz, you don't want to re-set it back to less than 80 Hz afterwards.


I like to initially EQ with the SMS-1 without the speakers running at all. Once I have the curve as flat as possible, I then turn the speakers on. I then use the "Phase" control setting to adjust the response around the crossover point. The Phase control has 15 degree increments plus a180 degree phase reversal switch. I try all the possible combinations until I find the one that yields the flattest response at the crossover.


Craig
 

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Discussion Starter · #13 ·

Quote:
Originally Posted by craig john /forum/post/18182254


I then use the "Phase" control setting to adjust the response around the crossover point...

thanks craig. i know you know a lot more about this than i do, but doesn't a phase adjustment undo the time domain corrections that audyssey has made?
 

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No, the Phase Control is used to time the arrival of the subs with the speakers at the crossover point. Think of it as a slight delay that moves the wave in time so the upslope of the sub wave arrives in "in-time" with the upslope of the speakers' wave. Otherwise, if the upslope of the sub arrives with the downslope of the speaker, you get cancellation and a drop in SPL at the crossover.


Audyssey's time correction reduces the ringing and overhang of the bass in the room. This is a completely different process than timing the sub and the speakers at the crossover point.


Craig
 

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Discussion Starter · #15 ·
gotcha.


i have an ME degree, so i understand what phase it. but i misunderstood what audyssey is doing in the time domain to be phase adjustments.


played with it again this evening...moved the sub ~8" right, but the phase adjust was the secret sauce! big adjustment (165*) fixed the crossover holes. thanks much.


i ended up with pretty solid 30-50hz cuts to drop back to where the mains were and a little sub-30 bump to boost my sealed box roll-off. kept boost to +3 max, some cuts at -8ish.


took a pic, but can't post it from this PC. we're on the road...that's for sure. i'll wind up '9' tomorrow and see what i've really done...
 

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Quote:
Originally Posted by craig john /forum/post/18172870


I do things in the opposite order. I run Audyssey *first*, then I use the SMS-1 to flatten the resultant response curve further. Let me explain my logic, and you can reconsider your use if you care to:


Audyssey is a multi-point EQ that measures an "area" and attempts to flatten the response over that area. In addition, it attempts to correct in the time domain as well as the frequency domain. The SMS-1 is a single point EQ that can only correct a single listening position and only in the frequency domain.


Therfore, I use Audyssey first to perform it's correction over the listening area. It usually gets the response closer to flat, but not quite totally flat. However, if you look at the time response, it shortens the decay of the bass over all the listening positions considerably. To me, this correction is more important than perfectly flat frequency response. Also, if you perform the SMS-1 single point FR correction first, Audyssey may measure a significantly different response at other LP's and may actually work to *undo* the correction you've added with the SMS-1. By running Audyssey first, you can usually get much smoother FR first, so you need to use less boost/cut on the SMS-1 to get flat response. Finally, you can get flatter response over the entire listening area first, then use the SMS-1 to flatten the response at the most important LP... the sweet spot, (where YOU sit).


For all these reasons, I run Audyssey first, then use the SMS-1 on the resultant curve.


Some other general comments;


I don't like to use more than 3 dB of boost on any single SMS-1 band. 3 dB of boost equals a *doubling* of the power required at that band. Also, if adding boost, I never use a wide Q, as this adds significant power requirements over a wider frequency band. If I'm adding boost at all, it is limited to 3 dB and over no more than 1/3 octave. BTW, nulls, or depressions in the response are much less audible than peaks, and it is less important to *boost* than it is to cut peaks.


I never "stack" filters, especially when adding boost, (see above, which is greatly exacerbated when stacking filters.)


I never use more than 6 dB of cut on any single SMS-1 band. 6 dB of cut equals a 75% reduction of power at that frequency band. I would prefer a few dB of extra SPL at a given frequency band than to neuter the output at that band by so much power. I feel it reduces the impact of the bass by reducing the power so significantly.


Here is what my final response curve looks like using the strategy I employ:




Note the Time/Energy/Frequency graph in the upper right. This shows there is very little ringing and overhang in my room and system, (for the most part, the energy has "stopped" with 100 to 200 ms if when it starts.) This is a product of Audyssey's processing, and of the bass traps and acoustic treatments in my room. IMO, this is more important than the flat FR curve in terms of sound quality.


Anyway, there are many ways to approach this issue. I have presented my logic and technique. You may find it useful and beneficial. Good luck.


Craig


Edit: I forgot to add one important thing: It is important, no matter which order you do this, to have the SMS-1 in the circuit when running Audyssey. The SMS-1 has some inherent delay, (it takes some time to process the signal... there is a A to D conversion, then the digital EQ, then a D to A conversion.) This all takes a little time, (~ 2 ms) that needs to be accounted for in the "Distance" setting set by Audyssey. When I run the two EQ's with Audyssey first, I place the SMS-1 into the circuit, but I set it for flat output, (no EQ applied.) Then I run Audyssey and it always finds the subwoofer distance about 6 ft. further than it's actual physical distance. This adds some delay to the speakers that allows the subwoofer to "catch up", so the waves from the speakers and the waves from the subs arrive at the LP at the same time. Once Audyssey has finished, I *then* use the SMS-1 to flatten the FR further at the LP.

Hi Craig,


Thanks for your well thought-out posting. Your point about having the SMS-1 in the circuit is very interesting in that it seems to overcome the traditional cautions about throwing off the timing performed by Audyssey when running the SMS-1 last.


However, Chris over at Audyssey is still dubious if the measured frequency response is at a single measurement location. Refer to the following posting taken from the Offical Audyssey thread:

Quote:
Originally Posted by millerwill /forum/post/17731538


I had a different experience with Audyssey with my new AVR (Onkyo 1007) than with my previous Onk 805. Not necessarily worse, just different.


I also have a SMS-1 in the loop, and I first looked at the FR with Audyssey 'off' in the AVR and all filters in the SMS-1 at 0. Sub is a Mark Seaton SubMersive, and it is probably overkill for my ~2000 cu ft room, but better too much than too little, right? I have its gain at -16, and the SMS-1 volume at 10. The FR has some large, broad peaks in the 30-50 Hz region. My procedures:


1) First method was running Audyssey first, then planning to 'touch up' with the SMS-1. Audyssey took down the broad peaks, but brought entire sub region (20-80 Hz) WAY down. I had to bump the trim up 6 dB or so to get things reasonable.


2) Second approach was to use the SMS-1 to even out the FR, and then to run Audyssey. The result was also a very good, even FR but the sub region was not cut down nearly as much.


My conclusion is that in approach (1) Audyssey over does the cuts it puts in, in order to even out the FR, while in method (2) it has to cut very little since the SMS-1 has evened things out. Audyssey, of course, also deals with the higher freq region which the SMS-1 doesn't touch, and also presumably puts in filters to deal with real time behavior etc.


Any thoughts from you gurus?
Quote:
Originally Posted by audyssey /forum/post/17732065


It's really not possible to draw any conclusions about the frequency response of the sub by using a single mic position measurement. You may get nice looking graphs on your screen, but they don't mean much unless you take a spatial average (RMS) with multiple measurements.

Is your graph at a single location, and if so, would it be possible to post a response spatially averaged over all the measurement locations? By the way, I am inclined to agree with your observation that decreasing modal ringing is more important than having a ruler flat frequency response.


Thanks.


Larry
 

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XTZ can, and does by default, average 3 measurement positions. I do not know for certain but I suspect that Craig's results are with 3.
 

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Quote:
Originally Posted by Kal Rubinson /forum/post/18270953


XTZ can, and does by default, average 3 measurement positions. I do not know for certain but I suspect that Craig's results are with 3.

Hi Kal,


Thanks for your response.


What does XTZ do with the Time/Energy/Frequency graph? Is that at a single location? To get a good idea of what is happening in the time domain will it be necessary to look at a Time/Energy/Frequency graph at each measurement location?


Craig brings up an interesting point about the importance of looking at the time characteristics. I notice that after flattening the frequency response many, perhaps most, equalization processes seem to also improve the time domain. That is they reduce modal ringing. However, I was wondering if there might be a point of diminishing returns where there comes a point when continuing to flatten the spatially averaged frequency response now starts to undermine the corrections in the time domain?


Do you have any insight on this subject?


Thanks.


Larry
 

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Quote:
Originally Posted by LarryChanin /forum/post/18271378


Hi Kal,


Thanks for your response.


What does XTZ do with the Time/Energy/Frequency graph? Is that at a single location? To get a good idea of what is happening in the time domain will it be necessary to look at a Time/Energy/Frequency graph at each measurement location?

You can to either single position measurements or 3 position measurements, at your choice. Both will show amplitude- and time-domain results.

Quote:
Craig brings up an interesting point about the importance of looking at the time characteristics. I notice that after flattening the frequency response many, perhaps most, equalization processes seem to also improve the time domain. That is they reduce modal ringing. However, I was wondering if there might be a point of diminishing returns where there comes a point when continuing to flatten the spatially averaged frequency response now starts to undermine the corrections in the time domain?


Do you have any insight on this subject?

I suspect you are right and small deviations in FR (particularly in the low bass) are less significant than uniform time decays, imho.
 
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