I need help with my room

Nate: Easy mistake to make when posting on a complex subject i.e. assuming that we know what you know. Other than that, i agree with what you said. That is, you left out just a few "small" details : )

My thoughts are that you would have gotten VERY different results if you would have taken the measurements with your Krell in the system. The high output impedance that Cary amps demonstrate will typically introduce very measurable divergences from "flat" frequency response in most systems. On top of that, those divergences from neutrality will vary in frequency and amplitude with the different loudspeaker / cable combinations that they are mated with. This is not to say that Cary amps don't or can't sound good, but that the results of mating this type of amp with any given speaker / cable interphase is most assuredly a "crap-shoot" at best. With components like this, it is strictly a matter of "system synergy" as the predictability factor based on science is very low.

As a side note, those that own Cary products and think that i'm slapping them in the face / stepping on your toes, please review some of my previous posts where i mention this brand. While i personally believe that Cary amps are not a very "linear" device, they are quite capable of producing very "musical" sound that is highly enjoyable and projecting vast amounts of spaciousness into a recording. Funny thing is, one of my other "favourites" when it comes to mass-produced tube gear would be Atma-Sphere amps, which measure VERY differently from Cary amps. Completely different ends of the sound and design goals spectrum, so go figure... : )

Other than that, if it were my system and knowing what i know now about the test conditions, i would consider the test runs that you did to be nothing more than an experiment and "learning session". If you wanted to do this "right", you really need to get your amp back in there ( or the amp that you intend to use in the near future ) and give it another series of test runs. Sean
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PS... If i remember correctly, Stereophile actually tested a Krell amp in the same issue that they did a Cary amp. John Atkinson said something to the effect of "If one of these amps is right, one of them is VERY wrong". Obviously, it all boils down to a matter of personal preferences : )

I'm not necessarily trying to get a flat response, I just want my system to sound better.

Nrchy, in another post titled How Important Is Flat Response you wrote:

It is possible to love a system that is not musically accurate. Just because a person likes the sound of their system doesn't mean it's accurate, and just because a system is accurate doesn't mean you will like the sound of it!

Has the measurement experiment altered your views. I hope not.

Also in that same thread I posted a link to a site run by Ethan Winer. There he has a graph of the bass response in his personal listening room. Ethan makes a living selling and advising people on acoustic treatments, yet the response in his own room doesn't measure flat.

It is easy to forget how little information I included with my posts. I figure since I know what I did, that you must too!

The measurements were taken many times. I think it was a total near seven. The microphone like type thing was placed on the back of the listening chair within inches of where my own ears would be located while listening. The speakers are about three feet out from the back wall and on the left side about two feet out from the side wall. On the right side this is not possible since there is a door on the side wall, and a little farther out into the room is a staircase going up. No room is perfect and mine is as imperfect as the best of them.

The measurements were taken with all room treatments in place, with the speaker placement adjusted, and then again with some, and then all treatments removed.

I should probably mention that I had Rooze’s Cary V12 monoblocks driving my speakers rather than my Krell FPB 200. I’m not sure how much difference that will make as far as measurements are concerned.

Sean, you need to keep in mind that there is a fine line between bravery and stupidity. Be careful not to give me too much credit. Carl is correct when he describes the listening room as a near nearfield. The speakers are about eight feet apart (I’m not home now, so I can’t give exact dimensions) and the listening chair forms a triangle with the two speakers with the chair, of course at the apex of the triangle.

I realize that most peoples systems don’t sound as good as they think it does. I was concerned about the accuracy of my system, hence the attempt at quantifying it. No audiophile worth his/her salt would say that they have wild frequency swings, or phases issues, and not feel the urge to hang their head, or at least, their salesman.

I probably have not taken enough measurements, but I’m wondering if I can do anything with the amount of information I have at the moment.

I admit that it is difficult to determine whether the frequency issues are speaker, room, or speaker and room interactions. Does it really matter what the source of the flaws is though? If I were willing to replace my speakers, or my room, neither of which is an option, then that would be more relevant, but I’m not in a position to do either, so I need to fix the interaction as much as possible.

Onhwy61, I have asked myself the question: how important is a flat frequency response at the listening chair. I just want to assure myself that I am getting a reasonable facsimile.

We did use the TACT in correction mode, and actually I preferred the sound without it, but I will readily admit that just because I like something, or even worse, am used to a certain sound doesn’t make it right. My goal in ‘opening this can of worms’ was to get a little better sound from my system as opposed to just having it sound like I want it to sound.

I don’t know if this makes any or much sense to anyone else, but that’s where I am.

PS...we didn't have time to try the Tact extensively in correction mode - we switched in a couple of stock correction curves but didn't spend any time trying to massage them into usable curves. My limited experience with the Tact is that it takes days, even weeks to get a good sounding response curve...and sometimes even then the trade-offs outweigh the advantages.

Sean, i was worried about getting Nate onto the measurement bandwagon and leading him on a downward spiral - but I made him do it anyway!!!(kidding).

I think if things are maintained in a certain context then there will be no permanent damage done. For example, setting a reasonable goal to ameliorate some of the obviously extended peaks and troughs, without striving for complete and utter perfection (the unattainable), is the safest way to approach this. The problem is that once the seed of doubt is planted, it tends to grow and get in the way of what we are ultimately trying to achieve - as you say, opening the proverbial can of worms.
It's over to Nate, but I think my approach right now would be to restore the listening room to its former state, with treatments in place, then to acquire a measurement tool that would allow him to see the result of each small change that he implements. Then slowly, perhaps over a period of a year or more, make subtle step changes, controlled and measured, to move him more towards a linear response, at the same time, allowing his ears to be the ultimate arbitrator between measurement and enjoyment.

Alternatively, given that Nate probably has more 'data' than most, perhaps take advantage of the Rives service, and have a professional assessment undertaken?
Rooze

I agree with your post Rooze. That is, enjoying one's system and knowing that it is as neutral as possible are two different things. That's why i said that i could understand if Nate or anyone else in a similar situation "quit while they were ahead". That is, stopped working and spending while they were still happy and not quite as broke.

It all boils down to personal preferences, perspectives and goals. Having said that, i think that doing something like this and then seeing the results is VERY frustrating, dis-heartening and will tend to eat at most folks from the inside out. It's a tough call as to what to do and how to go about doing it. That's why i applauded Nate's willingness to bare his soul in such a public manner and his willingness to ask for help.

Other than that, i agree that he needs to be more specific about what it is he wants to achieve i.e. more neutral in-room response, particular changes to tonal balance, etc... If he's happy with the system but not happy with how it measures, and he pursues the correction of the latter, the system may measure flatter. The question is, will he still enjoy the presentation of the system as much as he does now???

Given that most people think that their system is much "better" or "more accurate" than they think it is, they really don't know what they are getting into when they start looking at the testing of their system in this manner. This type of situation is typically a MAJOR can of worms that most folks are afraid to open. I don't blame them either as it gets very complex.

By the way, while you guys were doing all of this testing, did you use the TACT to as a correction device at all? If so, I have to wonder if Nate preferred the system in stock vs corrected form? I'm sure it sounded VERY different. Depending on which he preferred, that might give him a better idea of whether or not he should "mess" with his system or not. Sean
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I hope Nate doesn't mind me posting this, I don't want to 'steal his thunder' but there are some points that need to be added to help understand the measurements that we took in his room.
Firstly, I think it takes a brave person to look at a frequency respones curve and try to correlate that to how a system might actually sound. I'm barely familier with Nate's system but it sounds like one of the most 'together' and neutral systems I've ever heard. So to look at the graphs and assume specific sonic weaknesses requires a degree of courage and knowledge that I don't have.
A bit more about how we took the measurements:
I don't have actual distances from the listening chair to the speakers, distance between speakers etc, but Nate has the system setup for what I would describe as fairly 'nearfield' perhaps 8' or so from the speaker line to the chair....so as pointed out above, room/speaker interactions become a little less significant.
Also, the room to my ear is very 'dead' sounding with a good amount of diffraction and absorbtion, which I believe accounts for much of the neutrality. Later in the measurement process, Nate removed some of his acoustic treatments, and I felt that was a negative move and that the stage sounded at little more confined and that the tonal balance edged a little away from neutral and more toward bright. Anyway, I'll leave the rest of the room setup description to Nate, since that's his baby not mine.

We used the Tact RCS 2.0 for measurements, and used it in fully digital mode, that is without the need for using it's analog inputs and/or outputs.
Tact recommend setting up the unit to take 20 impulse measurements per channel, more if ambient noise is an issue. I set the unit up to take 35 measurements per channel, and we took several different sets of measurements from the same position, which I later overlayed to verify consistency.
I should have exhibited more foresight whilst taking the measurements however, by having Nate seated in the listening chair, or had cushions or something there to simulate the presence of a person. In larger spaces, these subtle details may not be significant, but it may have made an impact in Nate's room, I'm not sure.....
If you look at the overlay graph showing room treatments in place, versus room treatments removed, there are clearly some significant measured differences. Given that Nates room treatments were not physically large in terms of reflective/absorptive surface area, and 'volume', it could stand to reason that not having a person in the listening chair during the measurement stage could have 'fudged' the results to some degree.
I agree with Sean that Nate is a brave man, hanging his gonads out for all to kick. However, this approach might be missing one fundamental factor, and that is: 'what is it about the sound that I (Nate) am trying to change or improve?'

When I bought the Tact for use in my own system, I had some very specific goals - reduce some treble glare, add a little mid-bass warmth, extend the bass a little, cure some bass 'suck-out' problems at the listening seat.
Nates system, to my ear, doesn't have any of these issues, and doesn't really have anything that I can detect that is the result of poor speaker/room interaction. I think a clearer objective is needed to derive anything valuable from this experience....or, and this is a question not a statement - 'is it acceptable to approach this exercise like experimenting with new cables, for example - I don't really have anything to achieve specifically, I'm just look for all-round 'better'?

Could you please describe how the measurements were taken.

From looking at the graphs I don't see how you could describe the response as muted. The most prominent features show a recessed lower bass/midrange and an elevated upper midrange with a smooth treble. If anything, I suspect your system sounds slightly forward.

One question you really need to ask yourself is whether you really want flat response at the listening position. Smooth response, yes, but flat will sound very bright. If you're adventurous I recommend you get a parametric EQ and experiment. Use it to reduce the peaks in the room response and play with shelving the treble response to see what you think.

Nate, i'll start off by saying that you are a brave individual. You've laid your heart, soul, system and room along with all of its' non-linearities out for all to see and criticize. Kudo's to you for having the guts to do that. Having said that, i think that most folks would be utterly stunned if they saw the response of their system when obtained from testing like you did. I know i was when i first had access to upscale test equipment. Even just listening to the image shift when playing the Cardas sweep tone told me that something was VERY wrong. The funny thing is that moving over just one foot to either side and playing that same frequency sweep will produce DRASTICALLY different results. As mentioned above, that's why averaging of results becomes important.

In order for one of these devices to work and be properly interpreted, you have to take GOBS of readings. Something that most folks don't understand is that, if the speaker isn't very linear to begin with, you can't compensate for that with room treatments. That's why i've stressed speaker designs that take into account real world room acoustics with typical in-room placements. Most speakers, especially a lot of higher priced "audiophile approved" designs don't do this.

Other than that i don't know if you took any nearfield measurements of your speakers, but you should do that if / when you get a chance. This will tell you how much of what you are measuring is room based and how much is speaker based. As you get further away from the speaker, the room becomes a bigger factor. This is why some folks absolutely love and "preach the gospel" of nearfield listening i.e. less room interaction.

Other than that, your in-room response from appr 125 Hz up to appr 15 KHz varies +4/-5 dB's. This is actually not that bad compared to some that i've seen but could obviously use some help. Once again though, i don't know if you are fighting speaker problems, room problems or a combo of the two ( most likely ).

As to bass response, most rooms look absolutely horrible to say the least. Poor speaker design along with poor acoustics make for VERY "non-linear" response. For a peak at what the measured response is of someone else's system that has taken a lot of time in setting things up, take a gander at Joe's measurements regarding his "Critical Q subwoofer" installation. As a side note, i would encourage those that are interested in learning about woofer design and / or the "sealed vs ported" debate to give this entire article a read. It is quite educational and deals with real world situations and the design goals / trade-offs that we have to deal with.

Back on topic now, Joe's system actually measures quite good, yet it is something like +6/-5 dB's from 20 Hz to appr 15 KHz. It should also be noted that Joe chose to use a very revealing method to test his system, so it would look much "flatter" if he had used the standard 1/3 octave method that many others use.

As such, Nate has nothing to be ashamed or embarrassed about. While his system looks "rough", part of that has to do with the size of the graph used. If we were viewing a smaller graph length-wise with a narrower vertical gradient scale, the in-room response could have been made to look "much better". Obviously, his system isn't perfect and needs work, but the scaling of this graph somewhat exaggerates the results compared to what we are used to looking at.

Having said that, I have a lot of respect for anyone that would have both the guts and humility to post potentially "embarrassing" measurements ( only to those that aren't well versed in actual in-room response measurements ) and then ask for help in resolving those problems.

Not to single him out, and i know that he won't take this the wrong way, but even with the calibre and cost of gear that he's using, one can see how easy it is to end up with a "non-linear" system. On top of that, it is also easy to see how one could have a very different "sonic conclusions" when making comparisons from one system to another. That is, each system is going to produce unique deviations in frequency response ( and associated observations in timbre and transient response as they are all inter-related ). This is why i and many others strive to promote "neutrality" in both electronics and speakers, as a neutral response removes as much of the individual deviations out of the equation from system to system as is possible. Obviously, minimizing the deviations from a "flat" response can be a LOT of work and very frustrating to say the least.

With that in mind, my suggestion is to NOT make any brash decisions until you can make some very thorough tests and analyze the results. That is, IF you ( or anyone else in a similar situation ) aren't happy with what you are hearing. Obviously, some folks are content to listen to what they have and think that it is "as good as it gets" without really knowing what they are dealing with whereas others strive to achieve the best results possible. It would appear that Rooze and Nate are folks that fall into the latter category. As mentioned though, when one first takes steps like this, the "shock to the system" that you get as results may be enough to scare one away from seaking the "sonic grail of neutrality".

If you were to "quit" now and simply enjoy your system, i would understand. At the same time, i know that once someone sees this type of information about their system and know what is going on, it is a hard thing to forget about. As such, i would advise others to NOT take the steps that Nate did UNLESS you have the heart, soul and courage of a warrior. I say "warrior" as you'll have one helluva fight in front of you once you see what you're really dealing with. Sean
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I bet I am going to kick myself for wondering down this path, but I have to know. What is the reference used to conclude your system is muted to the tune of 6db?

Here is a link to the graphs http://topwebpromotion.com/nate.htm
I don't know if this will help at all but there are three graphs of what was measured in the listening room by Rooze.

Onhwy61's response sounds about right. Where you're measuring has a lot to do, as well as with speaker locations. Simply ploping your microphone in the room and measuring doesn't tell you much. Also, like he said, "is it being used right?"
You really should know what's going on with a room, and how to deal with it. This is why companies like PMI, Rivesaudio, and others get paid for consulting and room correction. There's some science and art to all of this...then you're ear's factor in for final say-so.
Doing some research otherwise will help tremendously.

It sounds like you're overreacting. I have been using a TACT system for close to 2 years and it's a wonderful piece, but it can easily be misused or misinterpreted. The key to using the TACT is obtaining an accurate measurement set. For best results you need to set the measure clicks to at least 50 and take readings from several different positions approximating where your head is during normal listening and use the averaging function. It's very important that the room is absolutely quiet during the measurements. HVAC noise, passing vehicles, cycling refrigerators can all screw up the measurements. Assuming all this was done correctly you still have to understand what the measurements are telling you. NO ROOM EVER MEASURES FLAT IN THE BASS. If all you have is a single spike at 40Hz and otherwise the system measures smoothly, then you've already done a great job. A relatively narrow bass peak can be easily dealt with via EQ or tuned bass traps. Depending on your taste in music, a little bump at 40Hz can be quite helpful in that it adds some growl to bass lines. Flat bass response can sound slightly anemic.

Ask yourself a question - does the system sound muted? Use the measures only as a guide and then let your ears tell you what is right.