Axiom Home Page Forums General Discussion Technical Questions Graph testing again, I'm confused, so is mojo :)

Ok, since I received my new 80's and 600 I thought I would do some more room freq response testing. Mojo had recently asked me if I was getting anything out of my 80's at the lower freq's using the test CD. To be honest, when I had my 60's, I'm not sure I monitored the woofers.

So today I've been doing a little testing using the Realtraps CD. To remind everyone, it starts at 10hz and goes up to 300hz in 1hz increments every 10 seconds. The result is a pretty good graph.

Here is where I'm confused. On my Denon I have my 80's set to "small" with an 80hz crossover. I would think as I approached the 80hz tones my 80's would start to kick in or blend with the sub. As I get to the higher freq's, the 600 would fade out and the sound would be just coming from the 80's.

Why the heck are my 80's drivers moving then at the lower freq's? 20, 30, 40, etc... the woofers are moving in and out like crazy, I think the midrange woofers are even seeing a little action. This makes no sense unless I don't understand the crossover setting and setting the mains to small?

Any ideas, this makes no sense.

Upon reading the instructions for the realtraps CD, I see one thing I was doing wrong. It says to run the pink noise test that comes with the cd and turn the master volume to 70dB from the listening position. Of course, this is after you have already calibrated you speakers to match using other methods. I have everything calibrated to 75dB.

Now that I have bumped down the master volume I'm going to try again. I still don't understand why the 80's would be active at those lower tests with an 80hz crossover and "small" setting.


Back to try again..

I am puzzled by your (and Mojo's) experience as well. I wonder if the slope of the cross-over is low, such as 12 or 6dB/octave, instead of the usual 24dB/octave. In this sceneraio, M80s are still in business at 40Hz, playing 6-12dB lower in effort. Is there a way you can adjust or see what the cross-over slope is?
John

I just got done jotting down the results after adjusting the master volume to 70dB, man what a difference. I'll run upstairs and plug them into my spreadsheet and try to post a graph soon...

Even at 20hz the woofers on my 80's were moving. I'm confused.

My 4806 has LFE + mains in the setup options if that's what you are referring to.

On my Denon 2805 if I set my mains to large in the speaker setup menu, this opens up another option where I have the options such as LFE + Main. However, when they are on "small" this option does not exist.

I'm not aware of any other option I've come across in the Denon when the mains are set to small...

Here is the graph I created tonight. In this graph I'm comparing the results from when I had m60's and an ep500 to my current setup of m80's and an ep600.

The results are pretty similar. I think I have the sub running a little hot and I'm sure if I could figure out why the 80's are going way below the 80hz crossover, that may change things. I've also included a graph of my room with no treatments back when I had the 60's and 500.

Looks like I've missed some good action over the last hour .

At least I know I'm not nuts! Or maybe Randy and I are both nuts .

We need others (with non-Denon amps) to try this. Maybe it's our amps.

Even if there is a problem with the Denon LFE cross-over circuit and it's letting all the lows through to the M80s, I am totally shocked that the M80s would even respond at 10 Hz.

By the way, as I've posted before, I, like Randy, have the M80s set to small and have only LFE set (not LFE + main). Randy, on my Denon 2105 I have the "LFE + main" option even when I set my fronts to small.

Why is this happening???

I'm going to have to dig out my manual, yeah, can't wait. Those Denon manuals suck.

I think the only way I get the LFE+Main option to appear is if my mains are set to large. This goes against everything all you guys have told me.

Hey boys & girls,

I just tried this again and it is only happening on DIRECT mode. It doesn't happen when in stereo mode (tone controls unby-passed) or any of the surround modes.

So I guess in direct mode, the LFE is sent to the fronts and sub regardless of speaker size settings or cross-over.

But it's still amazing to me that the M80 woofer cones move at 10 Hz!!!!! And why are the mids moving too?

This is pretty funny, I was just typing the same thing. I was going to ask you what mode you are using. I've always used Direct mode. hmmmm

Now I have to rerun my tests sometime. I was even using Direct mode for the RoomEQ Wizard tests in the past. It appears that since Direct and Pure Direct bypass some of the internal circuitry, they must ignore the small/large, crossover, etc...

So if I understand all this correctly, all these years that I've been listening to CD's in direct mode have been ignoring my small and crossover settings?

I thought the purpose of Direct and Pure Direct was to shut down un-needed circuitry, like the video section, to reduce the chance of any crosstalk and give you the best possible performance. What good is it if it ignores your speakers setup settings?

Yeah, same here. I've always been using direct. So I've got all of these freakin' graphs with the wrong mode . Boy, my daughter is gonna be pissed at me because she'll have to re-run all the tests .

Still, I can't believe that the M80s go down to 10Hz. That is just amazing. Granted, you don't hear anything because there is very little air movement from the relatively tiny woofers but I'd bet you can hear them at 20Hz.

What puzzles me even more though is the motion of the mids. That is just wrong! Aren't the mids and the woofers enclosed in separate compartments in the M80s? If not, the mids could be moving sympathetically and that's definitely not good.

I wonder if this is the way it works on other makes. It would help if others chime in here. I wish people would stop spending time with their loved ones and focus on our audio needs .

It would also help if the Denon user's manual was written by someone who had at least a grade 6 English education. I have to read most paragraphs 10 times due to poor sentence structure and even then I wonder if I've understood it right .

Randy, the crossover done by most receivers(including the 2805)rolls off the sub at 24dB/octave above the selected crossover frequency and rolls off the speakers at 12dB/octave below that frequency(this is said to give a good blend in the crossover area). So, as is often mentioned, this is a roll-off, not a very sharp cut-off. The result should be that the M80 cones would still be moving at those low frequency rates of vibration but the extent of the movement should be greatly reduced(i.e. they shouldn't be moving "like crazy"). Have you watched the cone movement with and without the 80Hz crossover to see if there's a visible difference? Another check is to listen in the two situations to determine if the low bass output is in fact reduced with the 80Hz crossover in effect.

Hi John,

I'll have to try what you mentioned. How did you acquire the information about the Denon cross-over? I've been searching for that info for the last few months.

Also, any theory on why the mids are moving at 10Hz? And they're moving "a lot".

I think JohnK just restated what I had tried to mention earlier. But it seems like the culprit was the Direct mode, which defeated settings like the cross over, individual channel volume, etc.

One subtle point about Direct mode is that on some processors this mode will defeat individual channel levels, cross-over settings, digital display, etc for both analog and digital inputs. In other processors, Direct mode will do these only for analog inputs and will maintain more functionality (like cross-over settings) for digital inputs.

John

Mo, I have my sources, but I'm not at liberty to reveal them. Okay, just kidding, of course, or maybe too many hotdogs today. Those attenuation rates are the standard ones determined by THX and others to be appropriate, and are almost universally followed. For example, Sound&Vision includes in their lab tests on receivers the crossover frequency and roll-off numbers measured, and these are nearly always at the specified rates and within a couple Hz of the selected frequency(they test 80Hz, when available). You could look up old Denon tests if you'd like.

As for the movement of the mid-driver cones, this shouldn't happen normally, but at least in Randy's case there again appear to be abnormal influences and spirits in his listening room which are trying to gain control of his M80s(and even a more powerful amplifier may not be sufficient to defeat them). Others might suggest some distortion products of the very low frequency notes, resulting in upper harmonics moving the mid cones, but I prefer the evil spirits hypothesis.

Yes, on many receivers direct mode is just that- it disables ALL digital processing (there by making the bass management adjustments not possible). This is why most SACD/DVD-Audio/Blu-ray/HD-DVD players that have multichannel analog outs have settings in them for bass management at the player level.

You could try playing the Realtraps CD in your DVD player connected by a solitary digital cable path. This should ensure your bass management settings will be in effect.

I agree there may be harmonic distortion of the 10Hz notes but these harmonic components would be very low amplitude. The mids are crossed at 160 Hz. That's the 16th harmonic! Something else is going on.

As for evil spirits, Randy and I are separated by 2,700km and I had Father Karras exorcise my basement shortly after it was built. So no evil spirits here .

Yes, in direct mode there's no bass management, and yes, LFE + Mains can only be applied(as has been pointed out in the past)when the mains are set "Large", because otherwise they don't play the lowest bass, of course.

Maybe we built our house on an old burial ground. Mojo, have you tried running any of the test using regular CD mode to see if the drivers are moving at the lower freq's?

Also, I forgot to mention that I'm using a HTPC and using SPDIF digital out to my receiver to play the realtraps mp3 files.

ps: Ever since the first time I watched The Shining, I've been haunted.

As I described in a post yesterday, the woofers and mids don't respond when in stereo mode (tone controls unby-passed) or any of the surround modes at 10Hz. They only respond in direct mode (tone controls by-passed). I haven't done any extensive testing to see at what frequency they start to respond.

Is this what you were after, Randy?

Going from memory, I believe on the H/K receivers Direct is tied to Stereo, ie the UI makes it more clear that this is "bypass everything, analog only, no crossovers, no nothing".

Sounds like the Denon makes it less clear that Pure Direct is the antithesis of Bass Management. It's strange -- everything else in their manuals and UI is so clear and intuitive.

EDIT -- Randy, you realize this means you need to re-do some graphs, right ? Will you be able to get the M60s and EP500 back ? I'm sure their new owner would understand that we are all interested in how the 60/500 and 80/600 compare when the crossover is working properly.

I expect this will mean some significant differences in response around the crossover region (80 Hz).

Yes, I was just curious of your findings with using Stereo mode. So basically using Direct or Pure Direct is like having my mains set to "large" even though I have them on "small".

I'll have to try using Stereo mode when I get a second.

I don't think so on the H/Ks. On mine at least, I don't think there's anything that's equivalent to Direct or Pure Direct. I still have bass management in stereo; I still get to set whether it's 2.1 or 2.0.

Yes, please do try it. I have to admit that I don't like this feature. I thought Direct just by-passed the tone controls and not the LFE management. Denon needs to change this or make it user configurable.

Has anyone come up with any reasons (besides harmonics) why the M80 mids are moving at 10Hz?

The HK equivalent of Pure Direct seems to be "Surround Off" without the "DSP" option selected. On my 630, the Stereo button seems to cycle through :

Surround Off (no bass management, no surround processing)
Surround Off + DSP (bass management but no surround processing)
5 channel Stereo
7 channel Stereo

On the 525, the "pure analog, no digitizing" mode is selected by choosing "Large" for your main speakers and "Surround Off" for the processing mode.

See page 22 of the following link :

Click me, click me !!

Ar har! Well, I never want to run without the sub, so...

I wonder if I am by accident, then. Odd.

10 Hz ought to be visible. Are they moving in and out at the same rate as the woofers?

I can definitely hear the M80 with a 20Hz tone. With one watt in, I get 66dB at 3 feet (1m) on axis which matches this graph.

By the way, I know I am putting 1W in because I adjusted the voltage at the M80 to be 2V. The graph above tells me that at 20Hz, the impedance is 4Ohms. So the power is (2^2)/4. So this means the M80 meets spec.

And the mids are moving at about half the rate but are in phase with the woofers. So this means the M80 is producing subharmonics (which may not be unusual for a speaker being driven outside its specified range now that I think about it).

I'm not going to worry about this anymore. The M80s shouldn't experience low frequencies such as these in normal listening.

Thanks for the detailed informatin Mojo. I believe you are right in that this shouldn't be a problem in normal use.

And I should add that we shouldn't be playing 10Hz tones through the M80s for long periods of time. The voice coils could heat up and vaporize.

Here is the difference between using Stereo versus Direct mode running the same test tones. Prior to running the tests I verified that I had my mains and sub calibrated to about 75dB. Also, I remember Jakeman saying that the sub should be 4dB lower to achieve the same SPL, so I turned that down a bit. It is interesting that the higher freq's are a litte higher overall.

Anyway, it appears that most of the changes below 80hz may be a result of using stereo mode versus direct mode.

It appears that the M80s are re-enforcing the bass from the 600. I'll have to try this with my system. I don't have an explanation for the 5dB difference in the "highs".

BTW, does the software that you are using have the capability of measuring reverberation time and impulse response?

Each horizontal line is 2dB, so I only see one spot with a 4dB difference in the highs, for the most part I'm only 1-2dB higher. I know JohnK said that there will be some overlap of the sub above 80hz.

The only thing I can think of is when I calibrated my system to 75dB, I may be a 1/2 dB difference or so higher for my main settings, I suppose that could result in some difference. Also, if my volume knob was a click or two different, that could change things.

There is no program I'm using for the above chart. I'm using realtraps cd and hand wrighting the results on paper, then entering them into a spreadsheet.

I have not had time to play with the RoomEQ wizzard yet. I know it has a lot of options, filters, etc. I pretty much use it to graph my freq response.

Sorry, two sons, 2.5 and 8 and their in bed.

Randy, the rule of thumb to calibrate the sub flat with the speakers at 75db using the RS SPL metre is to set the sub at 72.5db so you may want to bump up your sub gain by 1.5 db using 40hz as the reference. Also you may get flatter response at a location closer to the seats on your left sidewall. In any event I would try to place the sub to minimize that peak at 80hz. The EP600H works just as well standing up and the small posts would be facing the front. Your direct graph shows why running the system to duplicate bass through speakers and sub is usually not a good idea.

That huge null at 120hz is a problem. Perhaps moving the speakers a bit further apart or moving the seats slightly will help. Also I would experiment with a 100hz crossover and see if that helps reduce breadth of the null. Blending the speakers with the sub to obtain flat response at the crossover point is very important to getting good system integration.

Here is one of my recent graphs. I had reasonable response but had to tame several peaks with an SMS equalizer to get it this flat.

I think a 120 Hz dip corresponds to about 2.3 feet from speaker (driver, port, whatever) to wall or floor. If you have a bunch of "2 foot 4 inch" distances in your system you might want to try to change some or all of them.

Thanks for the suggestion John. I have a smallish null there as well. My mains and centre are about 2.5 ft away from the front wall. I will experiment with distance from the front wall.

Ditto John B., Randy. That 120Hz area wouldn't be an M80 spacing cancellation problem unless the separation was about a half wavelength at 120Hz(about 5')and of course it's much more than that. If it relates to driver to floor distances there might not be a reasonable re-positioning solution available, and receiver room equalization might be looked to.

Ok guys after a few years of hanging around these parts you would think I would have it all figured out. NOT

Now that it appears that "direct" mode ignores bass management settings, I've begun to listen to music using standard CD Stereo mode. I'm not very happy with the output overall, especially in the Bass category.

Keep in mind I normally have all speakers calibrated the same using my meter around 75dB. Lately, based on what Jakeman has provided, I've been calibrating my sub to be a little lower so it matches closer to my main settings. I also use a crossover of 80hz and "small" for all speakers.

My Denon 2805 only has one crossover setting, so this has always seemed to work great both for movies and music. However, this was because I have always listened to music using Direct mode and it now appears this is giving my 80's the full freq range since the bass management is bypassed.

When listening to music in "stereo" mode now, the music has no "punch" anymore. I assume this is because the 80's are now sending the freq's below 80hz to the sub. I know JohnK and others talk about this "rolloff" theory, however, this does not seem to be very active in this situation.

Highs/mids are fine, but the low frequencies sound thin. If I click the "direct" button on my Denon remote, BAMMMMM, the music sounds killer and has more life to it. From my understanding from everyone, this is more than likely due to my left/right 80 woofers are now adding addition dB's to the sub's output alone.

If I set my 80's to large, and listen to "stereo" mode, it sounds much closer to "direct" mode as the 80's are getting everything.

It appears that I can adjust the Sub level while in "stereo" mode and this will stay active only for "stereo" mode and not affect the other settings more movies, direct mode, etc.

But even when cranking up the sub level, it just was not the same as when the 80's were added into the picture.

So what do the rest of you do when listening to music? Which mode do you use and which bass mgmt settings are you using?

I feel like a newby all over again.

My H/K has two analog modes--direct and DVD audio. Direct passes a fullrange signal to the speakers. DVD audio utilizes the crossover setting in the receiver and sends a signal to the sub. I've been using the DVD audio setting mainly to help drown out my noisy downstair neighbors. I'm convinced they have small satellite speakers and a sub that tries to do everything. When they watch tv (all the time with the volume cranked) all I hear is the rumbling of bass in male voices. Anyways. . .

I know my Denon 2900 has a direct mode, but I haven't used it in a long time. I think you can set it so it shuts of all extraneous video settings, and I think you can make it only pass a full range signal. I'll have to dig out the manual.

Hi Randy;

When I have time to fiddle with receiver settings (my receiver's front panel display went out and I haven't gotten around to having it fixed) I listen to music with M60s in Large and sub disabled. Still like that best. When feeling lazy I listen with M60s in Small and sub enabled, ie same settings as DVD.

A few random thoughts :

When you made the graphs using the test CD, were you running in a different mode than when you do most of your listening esp. DVD ? I think the answer is "yes", which maybe means we need to revisit your experiences re: frequency response vs. enjoyment of the sound. Or did most of your comments re: sound quality relate to music played in the same receiver/speaker/BM mode as used for making graphs ?

I find my ears get used to a particular sound and any deviation from that sound seems "bad" at first. When doing your music listening previously, what is your understanding re: which speakers were active ? Did you have bass management at all, ie was the sub running ?

I remember being baffled a few months ago because moving your speakers around did not result in the response changes we expected -- maybe this is part of the reason ?

Randy,

For the benefit of others, I just want to keep everyone in the loop on the discussions we've been having.

I have my 600 set 6dB higher than my mains. When I switch from stereo to direct, I don't notice any difference in the bass. This is due to the fact that the mains contribute very little given the fact that I have my sub set four times louder than my mains. I think the math works out to a gain of 0.8dB with the M80s on large which is an inaudible difference.

Since you have your sub's SPL set to the same level as the M80s, you are at least doubling your output (3dB) in direct mode.

Have you tried turning up the gain knob on the back of the 600 (ie. not just through your amp)?

I hope one day we can start enjoying the music .

Hey John,

When I ran the test tones I've always used "direct" mode. It was not until recently when mojo mentioned that he noticed his 80's woofers/mid drivers were moving at 10, 20, 30, etc. Hz during the tests that I became confused.

This did not make sense if you have 80's set to small and an 80hz crossover. When using "stereo" mode I found recently they do not act this way, so it appears that "direct" mode bypasses any bass mgmt settings and sends the full range to the 80's.

When listening to music CD's, some music DVD's, and internet streaming music, I've always used "Direct" mode also.

It has always been my understanding this mode shut down unneeded video circuitry in the Denon and gave you the best possible sound. However, I never realized that my bass mgmt settings were being ignored. This is why the bass always sounded great, they were getting full range.

Many people have always told me that small and 80hz crossover is a great middle of the road for movies and music. So I've always assumed this was what I was experiencing. "Stereo" mode is totally different when listening to music than "direct" mode.

Maybe this is why so many people use say 40-60hz crossover for music listening. However, then my movies are not set right, as they need 80hz.

I suppose if my Denon allowed for different settings for different speakers, that would be helpful. I'm still not planning on using "large" for my 80's, but I may experiment with a 60hz crossover instead of 80hz. However, that may not be good for the rest of my speakers.....arrrrggg

Back in my original tests I would have been using Direct mode also, so my 80'z were altering the overall low freq shown on the graphs, which might explain the results when moving my 500 around...

Quote:

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Since you have your sub's SPL set to the same level as the M80s, you are at least doubling your output (3dB) in direct mode.

---

I'm confused, as I thought we determined there was no bass mgmt going on in the Dennon's direct mode? Wouldn't this mean the sub wouldn't be active at all in this mode, with full range going to the M80s?

Incidently Randy, I have the same experience with most 2 channel CDs that you do. I prefer to listen to 2 channel stereo with just the M80s, no sub. On my receiver the mode is called '2-Channel Direct'. As you said, things just sound as they have more punch, and for me even the upper frequencies sound more detailed. This is compared to the enhanced processing modes like Dolby Pro Logic IIx or Logic7. The added layers of ambiance in the other channels kind of detract from the clearness of the original 2 channel sound.

This is just me, I prefer the un-modified recorded sound over any type of synthetic ambiance my receiver creates. But it also depends on the recording, some stereo discs sound good either way, and some do not. Just so you know I also really do enjoy multichannel music, but it has to be mastered that way. Such as the 20th Annv. Brothers In Arms, or DSOTM on SACD, or the Beatles Love DVD.

As others have said before, the Axioms are very revealing to the original source recording. It has shown me there is a wide range of different quality recordings out there. Because of this I haven't found there is a perfect mode setting or crossover configuration to handle them all.

Randy,

I use an 80Hz x-over for movies and 40Hz for music. You of course have to remember to change the setting. It only takes 10 seconds or so to do this.

Dave,

I may not have been using the right terms above. I've done some testing today. It appears my sub is active in all modes; stereo, direct, pure direct.

In Stereo mode it appears what is going on is that the "small" setting with 80hz crossover setting is recognized. So I'm still getting some bass out of the 80's using the roll off to the sub.

In "Direct" mode I can easily hear some more reinforcement in the bass categories. I think this is because the 80's are being driven full range in addition to the sub. So I'm getting some dB increase.

I need to figure out what I should use for music listening in regards to settings and which mode. I do like to include my sub for music, as there is a lot of music that can benefit from the sub.

For music listening I could use Stereo mode and change the crossover, or bump up the sub level. Or, I could use Direct mode and leave it as is...so many options.

Not to mention sub calibration.

David,

In Denon's direct mode, a signal is actually sent to the sub AND the fronts.

As for simulated multi-channel, I now find that it works very well on all of the recordings I've heard. My experience is that you have to really watch the volume. If Raven Manor Cinema is very reverberant, turning on multi-channel very loudly will destroy the imaging due to high SPL reflections. My sweet spot happens to be at the exact interface between the direct field and reverberant field in my room. So half of the sound volume that I experience is due to direct sound and the other half is due to reflected. This is part of the reason why I need what some may call drastic toe-in. If I didn't have this much toe-in, the majority of the sound reaching my ears would be reflected and this would hurt imaging and intelligibility.

So you may want to try simulated multi-channel with the volume turned down and also experiment with toe-in of your fronts. I know that for you there's a fine line for toe-in because you have a multi-seat home theatre. But when you are the solitary listenener, you may want to toe-in more. And as I posted before, multi-channel may actually improve the frequency response of your listening environment.

Man this is confusing. I just noticed that in Pure Direct mode, the Denon WON't let me in the setup menu to adjust any of the bass mgmt settings.

HOWEVER, is "stereo" and "direct" modes you can, so this would almost appear that bass mgmt IS affected in those two modes, but this really does not explain why "direct" mode sounds much fuller in the bass category.

Mojo, I just tried using 40hz in "stereo" mode and now it sounds closer to "direct" mode....

fun fun fun

I don't have a PureDirect mode on my 2105 so I can't help you there.

My stereo and direct modes appear to be the same as yours.

So now let me stir the pot some more :

1. I was just listening to the Eagles Farewell Tour (awesome!) in DTS + PLIIxM (for my rears). When I set my mains to large and enabled LFE+mains, I got more bass punch. Why??? I already established that this shouldn't happen because I have my sub turned up 6dB higher than my mains. And this does not happen in other modes (direct, stereo, PLIIx...I haven't tried DD yet or DTS/96).

2. Has anyone tried setting all of their speakers to large to see how bass is affected?

I've been spending the last couple of days trying to re-position my 600 to get better results. Jakeman has been asking me to try locating the sub along my left wall next to the seating area to see if I get better results.

After a back breaking few days of trying various placements, phase, dB, etc. combinations, the sub ended back where I started. This position had the best outcome.

Now, I have made a few changes. I have found that the trim option of "half" gives be better results than "flat" or "full". Even though the pamphlet says to use "flat" most of the time or for larger rooms, "half" gives me better results on the graph.

I have also pulled out my 80's a bit more and toe-in is about the same, just aimed about a foot behind my head, in the primary position.

I still have a few nulls to work on, and I"m hoping my rear bass traps might help when I get them up.

Here is the graph.

Yeah Randy, interesting about the trim adjustment. I ended up with "full", but in a room much smaller than yours, of course. As to that big dip around 120Hz, as I commented in the previous reply, if that's a driver/floor bounce which would result from a little over 2' distance, there might not be a practical positioning change to eliminate it. I suppose as a temporary experiment you could raise the M80s a couple feet on some sort of support to see if that changed things.

Randy. That is a great looking curve compared to the first one you posted. You have really done a nice job of blending the sub with the mains to achieve a smooth response around the crossover point. That is critical to achieve seamless integration with your speakers. Another improvement was eliminating that huge null you had in the 80hz area which was a serious problem. Your bass below 40hz is on average 10db hot but many people prefer that "house" curve in the lower octaves. I'd prefer it flatter but in the tradeoffs you have had to do its a terrific outcome which will sound excellent in action movies.

The trim control on the EP subs is an excellent calibration device and its utility is very position and room dependent. Its impact will vary considerably depending on where you have the sub positioned relative to the mains and your phase. I always test it along with the other controls every time I tweak my system. Glad to see you put it to good use.

I'd say its time to put your feet up and enjoy the fruits of your labour. To improve your response much further will require a second sub, then you can look forward to wieghtlifting two heavy subs around your room.

Here is what my room currently looks like after I don't know how many calibration sessions. This was achieved with dual subs and acoustical treatments using heavy velvet curtains, bookshelves, panels and bass traps. Notice that not much equalization was required in the final tweaks and those required cuts and no boosts.

Thanks John and John,

It was very strange, if I tried to reduce the dB's of the sub to get them a little lower and not so "hot", sometimes the outcome would result in worse results.

I will post the "flat" response graph later today so you can compare. The "flat" curve was a little lower in the low end and not as "hot", however it did not seem to be as flat overall.

I really wish I could snap my fingers and have everything as perfect as possible.

Also, keep in mind, this graph was ONLY from the primary seat in the front row. I may move the meter to see what the other seats look like.

>>It was very strange, if I tried to reduce the dB's of the sub to get them a little lower and not so "hot", sometimes the outcome would result in worse results.

That might mean your mains are still pumping out bass in that frequency range and you are "reducing the cancellation" rather than "reducing the bass". Only a guess, of course.

I second the motion to kick back and enjoy -- from the primary seat in the front row, of course. You're getting some pretty good curves there. I strongly suggest that you not graph from any other positions until you have lots of time to kill.

Only thing I would check before popping the beer is whether the fronts of your mains are just over 2 feet from front or side wall, and move them a bit if so -- particularly if the two distances were both just over 2 feet.

Hey John the 3rd.

Yes, I'm sure some of the problem is the distance of my 80's drivers from the front and side walls. Right now they are about the same, around 27" or so. The problem is I don't have a lot of room to work. My screen is 10ft wide, my front wall is 15ft wide. That gives me 2.5ft on each side. However, I have the superchunk bass traps taking up some of the corner space.

There is only about 8" of front wall showing between the screen and each superchunk. With the rear ports filtering low bass into the room, not sure I want them aiming right at the superchunks, and sucking all the bass out.

I'll try to work more on repositioning, toeing in/out, and pulling closer/farther from the front wall to see if the nulls come up a bit.

>>Right now they are about the same, around 27" or so.

Close enough to 2'4" for government work

That's great. At least we have a pretty good idea what is causing that 120 Hz dip now. Park it in the back of your mind, sit back, and enjoy.

Just curious Randy. What effect did altering the crossover point have on your FR curve?

Bridgman, now you know when you give me ideas I can't just sit down and relax and enjoy.

Ok I played around with my 80's position again. I was able to pull them out from the front wall some more, as well as move them closer to the side walls. Now they are 22" from the side walls and 28.5" from the front wall. The best toe-in results were aiming about a foot behind my head.

I have also gone back to "flat" mode, as the manual states these modes increase the response above 33hz, it was just to much, so back to "flat" mode JohnK.

Jakeman, when setting the crossover to 60hz, the results were similar to "half" mode on the trim. From about 40-80hz, the entire graph shifted upwards about 3-5dB's.

Right now I have all speakers to small, 80hz crossover, phase at 180deg. The phase was the one that interested me. I was always under the assumption that when the sub wash up front in-line with the main woofers, that 0deg was the norm. When having the phase on 0deg it increased my bumps and valleys in the 40-50hz ranges.

Oh well, here is my latest results, notice my higher nulls have been improved thanks to bridgman's advice.

Here I thought I was done....



Here I think I'm about done.



Jakeman, do you think the feedback destroyer or sms-1 would be worth me considering?

>>I was always under the assumption that when the sub wash up front in-line with the main woofers, that 0deg was the norm.

Having both cones move in and out together is the norm. Depending on your equipment, that might be 0 or 180.

Randy, the big question is, can you hear a difference.

Randy. You may have done this already but if you haven't go back and check your sub and speaker SPLs with your metre. That is always a good thing to do anytime you change something in your system...and you have made many changes. From the looks of your graph you may need to raise volume on your sub a couple of db to level match them.

You could go with an equalizer but only if you are through experimenting with placement and acoustical treatments. Before trying equalization, a second sub would be my suggestion albeit the equalizer is a cheaper option.

Thanks John,

I'll have to re-check tomorrow night as the kids are in bed and their room is above the HT area.

I believe I have the sub and mains at 75dB, so from what you've talked about the sub would really be 77.5dB on the graph above. I have the denon about -7dB and the gain on the sub around 8o'clock if memory serves me well.

I usually use the Denon built in pink noise and manually adjust. I should have the Avia II one of these days, it will be interesting if it has any cool calibration features.

Randy

Ditto HomeDad's comment. There comes a point where squeezing that next bit of flatness into your system's frequency response comes puts you over the edge into the "listens to the equipment more than the music" category. Just watch your step.

True RTA is quite accurate with SPL and it doesn't need the same adjustment as a RS SPL metre. Your bass response is generally a couple db below 75db, except for a couple of peaks. It looks like you may need to raise sub volume slightly. Its just tweaking at this point and its looking very good overall.

I agree you should let your ears be the judge and its nice to know your reference settings.

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"listens to the equipment more than the music" category

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I've certainly seen a ton of measuring. Where did the listening come into play?
I must've missed that thread page.


Still all interesting, no matter how fanatic the goal. My limit would have been reached long before SirQ's though.
Someday i will find a laptop and use it to measure the response in our media room. Someday....

Randy is still working on the equipment to allow double-blind listening tests while moving speakers and installing room treatments

Until then the best we can all do is make a series of changes using response curves to identify likely candidates for listening -- then listen for a while and see if the results match the graphs. I think it's fair to say that in Randy's case the process is still going because some of the receiver settings resulted in audible results different from measured results, and only now are all the pieces fitting into place.

Or maybe he is crazy. You'd have to ask his neighbors. We know what his wife would say.

If Randy wants to do it right, he should first establish the transfer function of his ears. Then he should adjust the response of his room to compensate for his aural inadequacies.

Until he does this, he certainly won't earn my respect .

I think I am going crazy. Just as I thought I had everything right, and learning a little about calibration/placement...I'm starting to doubt I know what the heck I'm doing.

Tonight I was listening to various music CD's to see what I could hear after the above adjustments. While I'm currently in the Jackel and Hyde phase of my amps breaking in, I noticed something weird, not related. By the way, the amps are really starting to open up and sound unbelievable.

Back to the issue...when listening to a few of my favorite songs I noticed certain strums of the bass guitar were lacking. As soon as I switched the PHASE switch back to 0deg, Wowwwwwww there was the bass I was used to hearing.

We are talking a huge difference when monitoring the spl meter and switching back and forth on the phase. What confuses me is that my graph was not as flat when using the 0deg phase, 180 gave me better results. However, for output and better sound 0deg seems to be better.

I would have to really bump up the dB's in 180 Phase to get similar results, then everything is not calibrated at 75dB anymore.

A few thoughts. Did you raise your sub volume 2-3 db as it looked low? My guess is that your sub is calibrated below the levels of your speakers based on the latest graph. How do you have the delay set in your receiver? I would also suggest experimenting with the delay settings while listening to the bass tracks of your favourite songs to find what sounds best to your ear. The delay settings in the auto-programs are just not reliable.

Finally if you are spending this much effort I strongly suggest you buy a good calibration disc like Avia to make sure your signal from player to receiver is calibrated. Adjustments to only receiver test tones may not give you the best results. That's what I found with my Arcam processor, which is why its best to calibrate from a disc in the player or in your case from your HTPC.

Keep in mind that your curve isn't as peaky with your more linear FR curve so the "hot" bass you were hearing at certain frequencies is no longer as prominent. Many people report much the same thing when they calibrate a flatter FR but they also report hearing more detail in the bass after an extended listening session. If after a few days it still is not enough bass for you then raise the volume on the sub until it sounds better to you. Make note of the volume setting that gives you the flattest response however for reference purposes.

I am concerned about the 180 degree setting as I would have thought leaving it at 0 if its positioned right next to the mains would be preferable. But if 180 gives you flatter results then thats the better place to leave it. Dialling in phase isn't as straightforward as it appears since drivers can go our of phase at different frequencies. Its best to aim for the phase setting that gives you the smoothest response at the crossover point then use the other controls to smooth FR elsewhere in the band.

Dialling in subs to get maximum performance in your particular room can take a while, so hang in there. Once you get it set up optimally it makes a sonic world of difference.

Conventional opinion says to calibrate the sub to the same level as the speakers but I'm not convinced that's correct.

Our ears are about 40dB less sensitive to a 20Hz tone than to a 1KHz tone (that's ten thousand times less sensitive) for normal listening levels. Given our ears' decreased sensitivity to lows, we need to turn the bass up. We can't turn it up 40dB because as the frequency increases, our ear becomes more sensitive and the bass would be too hot. This is where a loudness control would be very useful.

I've found 6dB above my speaker levels to be a good compromise for my room. It sounds just right for music and I have earth-shaking LFE during movies.

As for the phase, the M80s are out of phase with the input signal by 45 degrees at frequencies below 50Hz as shown here. We'd have to know the phase response of the 600 to do some analysis. The phase is also dependent on the distance from the listener and also the relative orientation of the speakers to the sub. And of course like Jake said, the delay setting in the receiver.

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phase of my amps breaking

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Your amps are breaking?
I would get a return on those babies.
Once those electronics start to go, smoke appears and there's no stopping it.