Sub Equalization and Audyssey

ddank

Hi everyone.
I have a simple question. I'm replacing my 8" sub with a 10" sub. (both velodyne deq). It's going in exactly the same location. I can equalize the sub for my room using its own mic and auto eq process.

So here's the question. Do I still need to re-run the Audyssey auto setup in my receiver?

Thanks for your help.

domflane

You might as well, I think it'll give you better crossover points and volume levels so that everything blends better. Plus it's not that hard

ddank

domflane wrote: »

You might as well, I think it'll give you better crossover points and volume levels so that everything blends better. Plus it's not that hard

Thanks for the reply. I understand why the volume levels would need to be adjusted but why would the size of the sub (going from 8" to 10") change the crossover points. Doesn't that have to do more with the size of my surround & center speakers?

Syndil

Volume, nulls and phase might all be affected. Crossovers should not be.

ddank

Ok, so I hooked up the 10" sub, ran Audyssey (exactly like I did with the 8") and got my settings which were basically the same as what I had before. Surround levels the same. Distances the same. Crossover the same.

Here's the difference:
With the 8" the sub out level on the receiver was -3. Had volume on sub at 35.
With the 10" the sub out level on the receiver was -4. Put volume on sub at 35 to compare "apples to apples".

So then I listened to a test. A part of a movie that had a heartbeat. With the 8" I could feel the thump. With the 10" - not really. I changed the sub out level from -4 to zero just to test. Left the volume the same. Still not as strong as the 8". Found that to be the same with other test audio that I have been using as a frame of reference.

Why would that be? Shouldn't I get more thump from the 10"? Even if I did an exact comparison where the sub out level was -3 and volume on sub at 35 for both subs wouldn't the 10" still give you more thump just because of size?

Confused.

thsmith

You need to measure your sub freqs using a tool like REW. I suspect the output and freq curves on the 2 subs are different.

Syndil

The problem could simply be that the 10" sub was out of phase. Flip the phase switch and try it again. If that's not it, you could have a null being produced with the new sub.

ddank

Syndil wrote: »

The problem could simply be that the 10" sub was out of phase. Flip the phase switch and try it again. If that's not it, you could have a null being produced with the new sub.

I've tried the different phase setting on my sub (0, 90, 180, 270). No noticeable difference. What's a null?

Syndil

A null occurs when the soundwaves bounce around in the room in such a manner that, at certain frequencies, they cancel each other out. The opposite of a null is a peak, where the soundwaves bounce around in such a manner that they combine at certain frequencies.

You could do as thsmith suggested and use something like REW to test for nulls/peaks. You could also find a DVD with THX Optimizer on it and run the subwoofer test to see if you can hear any nulls or peaks.

Either way, the solution may be moving the sub to a different location or adding room treatments to your walls.

Tour2ma

Good stuff on the phase and all... Couple other things occurred to me...

ddank wrote: »

Here's the difference:
With the 8" the sub out level on the receiver was -3. Had volume on sub at 35.
With the 10" the sub out level on the receiver was -4. Put volume on sub at 35 to compare "apples to apples".

Shouldn't I get more thump from the 10"? Even if I did an exact comparison where the sub out level was -3 and volume on sub at 35 for both subs wouldn't the 10" still give you more thump just because of size?

Just to double check (not to insult you)... the new 10's volume was set to 35 before your ran Audyssey... yes? I'm guessing yes, but the way you wrote it leaves some room for interpretation...

Anyway... Looking at Velodyne's site you traded up to 69% more cone area, but less than 10% more amp power. Seems to me like a recipe for less "punch" or thump.

At what frequency are you crossed-over? What mains are you running and fed by what AVR/amp? If they will let you move your cross-over down, you may get back your punch.

ddank

Tour2ma wrote: »

Good stuff on the phase and all... Couple other things occurred to me...


Just to double check (not to insult you)... the new 10's volume was set to 35 before your ran Audyssey... yes? I'm guessing yes, but the way you wrote it leaves some room for interpretation...

Anyway... Looking at Velodyne's site you traded up to 69% more cone area, but less than 10% more amp power. Seems to me like a recipe for less "punch" or thump.

At what frequency are you crossed-over? What mains are you running and fed by what AVR/amp? If they will let you move your cross-over down, you may get back your punch.

Thanks for the reply. For both subs I set the volume at 30 (the manufacturer preset) before running Audyssey and then moved the volume up to 35 just like I had it for the 8" to compare.

Here's my setup:
Center and Surrounds: Polk RM75s
AVR: Denon 1611
Sub: Velodyne DEQ

Crossover:
Front: 100
Center: 110
Surround: 100
This is what the crossover has come out to each time I've run Audyssey so my satellites are outperforming their specs. (I actually called polk about this because specs say crossover is 120 but and that's what they told me.)

UPDATE: After all this I decided to hook the 8" again and rerun Audyssey. Bottom line is everything is sounding great. Actually getting great rumble and thump without experiencing "listener fatigue". Maybe the 8" is just better for my room acoustics.

Thanks to all.

Tour2ma

Whether 30 or 35 the main thing was you performed an apples and apples cal... Calibrating to 30 and then raising to 35 just runs your sub "hot" and that's typical for movies.

Your speakers are RM7's. RM75 was nomenclature for a 6-piece sub-sat system Polk sold. It included 5-RM7's and a PSW650 sub. I'm guessing the 120 Hz figure Polk was quoting was a lower "overall" frequency limit.

Given the FR limitations of your

Though it strikes me as a bit odd that your AVR is crossing your RM75 center a tad higher than your mains and surrounds (if it's higher, on top of your monitor, maybe ceiling reflections...), I'd tend to trust that your Denon is finding the best blend point.

But back to your "punch" issue... the best I can do is go by the spec's I can find on your sub/ sats...

Frequency Response (+/-3 dB/ Overall)
RM7 ..... : 140-20k Hz/

---

DEQ-8R : 32 - 120 Hz / 17 - 240 Hz
DEQ-10R: 28 - 120 Hz / 16 - 240 Hz

And for contrast the original Polk sub was:
PSW650 : 28 - 125 Hz / 25 - 180 Hz
2 - 10" woofers + Power Port
Continuous Output 165 watts/ Dynamic Output 250 watts

Nothing is jumping out at me beyond my original power to surface area ratio observation. I just don't see the 10's footprint being different enough to alter the room response. But sometimes when you get one thing in your head it blinds you to other possibilities...

At any rate glad to hear you got your jollies back... Maybe sometimes bigger is not better afterall...

Then again, if you are stuck with your DEQ-10R, you might consider stacking your 8 atop it... :idea:

Thomasjclark45

From what I have learned from my oldshcool car audio, is that the smaller the sub, the more punchy it will be. The larger the sub, the more it will rumble. This obviously has to do with the frequency, which is lower on larger subs. From the specs given above I see that there is only a couple of hz difference between the 2 so this may not be true. What is the sub highpass filter set at on the sub itself? I know that on my Paradigm sub, when I turned the high pass cut down on the sub itself, to around 60hz it got much louder, almost overbearing, and seem to humm constantly in when watching movies. After re-reading the posts, I relized that main question is about level, when it should be about frequency. With the 8" I had (which was a cheap sony mind you) it responded better in the range of 70hz to 120hz. This delivered the right amount volume/punch combination. It could not produce the power on the lower end (<70hz) to produce enough rumble, but on the upper end it gave plenty of punch (>80hz). When I moved to a 10" it was good all around for the most part. It had a good amount of rumble but still retained some punch. Now I have a 12" which can vibrate stuff off the shelves if not set properly, but there is no punch, only rumble. This sub preforms best below 70hz. I have the LFE cut off on my AVR at 60hz. All of my speakers are set on the low end at 40hz, which seemed a little low to me, but that is what Audyssey set them at, with the exception of my center which is at 60hz. So having the LFE cut set to 60hz makes sense, but if your speakers are set at 120hz then you would have quite a gap. My last system had a gap becuase the receiver would not let me set the speakers below 100hz, so it set my sub at 80hz. When I set it to 120hz to have some overlap, it just did not sound right.
As Tour2ma recomended above I would use both of them. Set the cutoff on the AVR to 120hz then use the cutoff on the sub. Set the 10" highpass cutoff at 60hz - 80hz and leave the 8" set on full or 120hz.

kuntasensei

Just so we're clear, an "LFE cutoff" doesn't affect the other channels - just the LFE channel of a digital bitstream. That doesn't filter anything from the main channels, nor does it filter the subwoofer output as a whole. Subwoofer output does not equal LFE output. All you're doing by using an LFE filter (commonly called LPF of LFE on most receivers) is throwing away information from the LFE channel of digital mixes (which don't typically have any significant info above 80Hz, but there are harmonics up to the brickwall of 120Hz that the LFE channel is designed with). I can not say this loud enough: THE ONLY CORRECT SETTING FOR LPF OF LFE OR "LFE CUTOFF" IS 120HZ! Anything else throws away audio in the LFE channel of the digital mix, however minor, and this setting does NOT affect bass redirected from the main channels AT ALL.

When speakers are spec'd with a low-end of 120Hz, they often perform better in-room, because those ratings are anechoic. Your room itself typically extends response below the -3dB point in the specs. That said, it's often a good idea to bump the crossover back up closer to the spec'd -3dB point because crossovers don't just quickly transition; they're a gradual curve from speaker to sub (typically a 12db/octave filter paired with a 24dB/octave filter, with the point where both speakers are putting out the same amount of info being the crossover point), most audibly over about an octave. You don't want the natural rolloff of the speaker at the low end to cascade with the rolloff being applied by the crossover network, because that will give you a gap in response just below the crossover range.

The reason the above is important is this: Audyssey detects the -3dB point of the speaker IN YOUR ROOM. It then passes that info on to the AVR's software to set the crossovers. The point that actually gets set varies between brands, because some of them don't follow Audyssey's recommendations on how to set this. Bottom line: If your speaker is spec'd for 140Hz on the low-end and detects as 100Hz, manually set it closer to 140Hz and you will get cleaner sound and better bass reproduction. Turn any filters on the subwoofer itself to their maximum/off settings before auto-calibration so that they don't cascade with the digital crossover being done in your AVR (and so the analog filter on the subwoofer doesn't cause electronically-induced delay in arrival of the sound to your listening position, which can throw off the subwoofer distance/delay done during calibration). And for that same reason, don't change the gain dial on the subwoofer AFTER you do the auto-cal; use the subwoofer trim on the AVR itself if you want to boost bass.

kuntasensei

To the OP, a few suggestions:
1) Make sure your sub is set to Subwoofer Direct so you're not cascading with the filters in the AVR.
2) Make sure your sub isn't within 3" or so from a wall so that you don't get any bizarre frequency issues (especially true with drywall, which can basically act like a passive radiator and throw off your calibration). Probably not a huge issue with your DEQs, since they should be front-ported.
3) Try a run of Audyssey without the EQ'ing on the sub itself. The Velodynes use a 5-band EQ for general equalization, whereas Audyssey MultEQ uses hundreds of data points to create an inverse filter. If the equalization in the sub itself monkeys too much with the phase relationships, it can potentially be harder for Audyssey to line things up in the time domain so that everything's in phase across the frequency range.
4) For the same reason you don't want to have the subwoofer too close to a wall, you don't want to do any of your mic positions for Audyssey within about a foot of a wall surface. Doing so can pick up reinforcement from the room boundaries, cause it to excessively reduce bass during equalization.
5) Do all 6 positions for MultEQ that your Denon allows. Do the main listening position, at least 18" to the left of MLP, at least 18" to the right of MLP, then mirror those three positions 12-18" further into the room to give Audyssey a better general sense of the frequency response in your listening area as you get away from room boundaries. You'll end up with a much better subwoofer calibration.
6) If you're not using a tripod/boom for the Audyssey mic, BUY ONE. You can get a cheap one at Amazon for under $20, and it's an absolute necessity for Audyssey equalization. It lets you place the mic at ear level and get the hell out of the way during the frequency sweeps.
7) If you are using a tripod, make sure the mic capsule is slightly above the level of the back of your seating if at all possible. Reflection/absorption of your seating itself can screw with Audyssey's readings... and as with all things audio, garbage in = garbage out.

Thomasjclark45

There is some great information here kuntasensei, but I have some questions. Keep in mind that I'm not trying to questioning your opinions, just trying to gain some insight. You stated that the only correct setting for the LFE is 120hz, but Lucas states that it should be set at 80hz, trust me, I tried, but did not like it. Now, from what I understand is that the LFE is a frequency setting just like the rest of the speakers only it only has an upper limit cut instead of an upper and lower like the rest of the channels. Now, if Im running the rest of my speakers at a lower limit of say 40hz then shouldn't I have my sub set lower to prevent overlap? It seems to me that when my sub is set at 120hz and all my speakers are set at 40hz then Im pushing out 40hz to 120hz through both my speakers and my sub which seems overpowering. Also, with the sub x-over at the 120hz range, I hear diolouge through my sub and other higher end noises which I do not beleive should be there. Again, I am a greenhorn compaired to most of you and do not pretend to know everything or anything for that matter, just trying to understand all the nuances involved. Also, could you explain what the -3db point is, I asked it in another post just before i read this one, and the 12db and 24db octave filters are? These are things that I never understood, nor bothered to ask.
Thanks for you Insight

Tour2ma

kuntasensei wrote: »

Just so we're clear, an "LFE cutoff" doesn't affect the other channels - just the LFE channel of a digital bitstream. That doesn't filter anything from the main channels, nor does it filter the subwoofer output as a whole. Subwoofer output does not equal LFE output. All you're doing by using an LFE filter (commonly called LPF of LFE on most receivers) is throwing away information from the LFE channel of digital mixes (which don't typically have any significant info above 80Hz, but there are harmonics up to the brickwall of 120Hz that the LFE channel is designed with). I can not say this loud enough: THE ONLY CORRECT SETTING FOR LPF OF LFE OR "LFE CUTOFF" IS 120HZ! Anything else throws away audio in the LFE channel of the digital mix, however minor, and this setting does NOT affect bass redirected from the main channels AT ALL.

kun-sen,

If the above is true, then why is any adjustment available? The OP's Denon has adjustments of 40, 60, 80, 90, 100, 110, 120, 150, 200 and 250 Hz. While 120 Hz is the default (and the Dolby Labs' standard) why would others be available if they can only diminish the experience? Why give the owner the option to eff it up?

Not trying to insult here, but do you have a reference link? Everything I have found Googling that approaches your LFE caution is related to encoding .1 information... that the maximum frequency you want to encode to the .1 ch is 120 Hz because above that point the listener will surely locate the sub.

I know that the difference between the LFE channel and the subwoofer output is that the LFE channel is used to carry additional bass information in the Dolby Digital program while the subwoofer output represents how some or all of the bass information will be reproduced.

I know that while Dolby Digital programs may include a bass-only LFE channel, this channel does not correspond directly to a subwoofer output. It is possible for a program to contain an LFE channel, but a decoder may provide no subwoofer output because all of the bass information in the program, including the LFE channel, can be reproduced by the main speakers.

I also know that the opposite is also true: it is possible for a program to not contain an LFE channel, yet a decoder may provide a subwoofer output because some or all of the main speakers are unable to reproduce the bass information in the program.

But in addition to LFE, there is also the matter of setting speakers "size", i.e., "Large" or "Small". And when Small is selected, then there is a range of frequencies at which the bass duties for any or all of the 5 or 7 (or more) channels to the left of the decimal point can be crossed-over to the sub.

kuntasensei

Why do they give the option? Well, in the case of THX-certified receivers, they're required to give you the adjustment to make them compatible with THX-spec'd subs (which are made by design to not handle above 80Hz well). If your subwoofer handles up to 120Hz (and the vast majority do), 120Hz is the correct setting so you don't truncate the audio placed in the LFE channel. Now, by virtue of mixing standards, not much above 80Hz is placed in the LFE channel anyway... but as with any sound placed in a channel, that sound has harmonics above those frequencies that give it its perceived tone. The LFE channel is brickwall filtered at 120Hz by design. If you place a filter on it again at the AVR, you are basically rolling off content that is supposed to be reproduced by your sub. It doesn't go to your other speakers... It's just GONE.

You're making my point for me, actually. The bass from the main channels is redirected to the subwoofer by way of the crossovers on the AVR when they're set to small instead of Large/full range. The LFE channel, however, is always sent to the subwoofer if one is present (otherwise, in a system with no sub, it is typically summed into the mains). Therefore, the subwoofer output in the vast majority of cases is LFE summed with the redirected bass from the other channels. And even that can vary from channel to channel. You could have an 80Hz crossover on your mains, 60Hz on your center, 80Hz surrounds, and the LPF of LFE at 120Hz... and you will lose no information from any of those channels so long as the filtering on your sub is disabled or set to its maximum. The filter on LFE only affects the LFE channel, not the subwoofer output as a whole. So in the previous example, the subwoofer output would equal the sum of the full unfiltered LFE channel and the bass redirected from the other speakers based on their crossover points. Changing LPF of LFE to 40Hz would have zero effect on redirected bass... It would just throw away the LFE content above that 40Hz point.

The point of setting crossovers for the other channels at 80Hz or below is so bass in the directional range isn't sent to your sub more than to the intended channel, in which case it would seem to come from the sub instead of that channel. Localization is bad. However, the LFE channel is SUPPOSED to come from your sub. The mixers ensure that there is no directional content in the LFE channel. However, there IS content in the LFE channel up to 120Hz, and throwing it away alters the perceived tone of the low frequency effects.

Don't take my word for it... but Chris Kyriakakis of Audyssey? He might know some stuff.
http://ask.audyssey.com/entries/321931-lpf-on-lfe
http://ask.audyssey.com/entries/230307-lfe-setting

And Thomasjclark45, read the following for info on how crossovers work:
http://en.wikipedia.org/wiki/Audio_crossover

It seems to me that when my sub is set at 120hz and all my speakers are set at 40hz then Im pushing out 40hz to 120hz through both my speakers and my sub which seems overpowering.

Negative. If you set your mains to 40Hz, the subwoofer primarily only handles the content below 40Hz for that channel. I'm simplifying here, because as I said before, it's a gradual transition... with the crossover point being the point where the speaker and sub are both producing it in equal amounts. The whole point of the 12dB/24dB configuration of the filters is so the rolloff to the sub happens smoothly, without letting too much of the content above the crossover point get to the sub and ruin directionality from the main channels. For more info on this type of filtering, see:
http://en.wikipedia.org/wiki/Linkwitz-Riley_filter