Is a perfectly flat frequency response always a good thing?

[fjhuerta]

Hi all!

After more than half a year of playing around with my Nat-P's, I finally found a network that made them perfectly flat. Gone are the peaks and valleys, and they are replaced by a perfectly flat on-axis response.

But...

I told my wife to give me her opinion of them. We had been listening for months to a pair of Monitor Audio Silver RS8 speakers, which have a rising FR from 2 or 3 KHz up. Anyway, without me telling her anything, her opinion was "they sound pretty...uh... flat". And it wasn't a good thing (suffice to say, I'd really like to have her sense of hearing. It's not the first time she's perfectly accurate in her comments).

I did some work on the crossovers today, mainly changing a conjugate circuit on the tweeter side, shaping the response upwards from 3 KHz up (not in any way near the slope of the Monitor Audios, though). I had now an extra 2.5 dB or so at 10 KHz. She was happy and thrilled. I, myself, thought the speakers came alive with that change.

I did some informal off-axis measurements, and the speakers are flat at 20° or so.

I've been thinking a lot about this. Most designs I've seen aim for flat FR on-axis. I right now have an almost flat response off-axis. I do not have a reference to compare them with, so I'm not sure whether they do sound better this way. They do sound a bit more natural to me, but that could be because I'm used to a "colored" speaker.

So... what is correct? Flat on axis, flat off axis or...???

[JonMarsh]

I usually shoot for fairly flat at 15 degress off axis. But one must consider the total power response and what the rest of the cabine/drivers besides the tweeter does. In the "old days", the norm was to expect a slight down slope in the power response from 1 kHz on- much music is recorded "bright" so it sounds OK on less than perfect speakers, such as car radios (Not amped up car stereos).

Voicing is a pretty sugjective thing, and a lot depends on the rest of the system. Some people like what I would call a "HiFi emphasis in speakers, a slight up slope in the treble, such as those Totem Forests JonW has and likes. But I think that's only called for when you're compensating with other issues in the playback system, such as a lack of clarity, or too much of a downslope in power response due to poor off axis response.

You have to be careful, I think, becuase making speakers a bit bright can wind up with an "etched" presentation- sounds more detailed, and makes up for not listening to music at lifelike levels (remember, the loudness curve has issues in both low frequencies and high frequencies. Ultimately, I prefer shooting for a neutral transducer presentation and by design balancing the on and off axis sound- they should track very closely, as a function of design, including choice of enclosure or no enclosure, drivers, and crossover design. In general, less room interaction is better. With box speakers, that's difficult to do, particularly in a smaller room, when the midbass can be emphasized by too close placement to walls or furniture boundaries.

Just my 0.02. YMMV.

[AJINFLA]

So... what is correct? Flat on axis, flat off axis or...???

Both.
Read all the Harman white papers, beginning with this one.

http://www.harman.com/wp/pdf/AudioScience.pdf

What do Geddes, Toole, Linkwitz, Danley, etc all have in common?
That's right, they are paying attention to what goes on off axis as much as on.

cheers,

AJ

[DougyD19]

I'd like to know how many people spend lots of money on crossovers making the speakers flat to turn around and mess with the EQ settings just to add or subtract additional response.

How much can the dynamic's of the room really change mid/high frequency output of the speakers.

[wmilas]

Well it depends what freq. range you are talking about.

I'm by far an expert, but if you go over to some of the forums (home theater shack) that deal with sub setup (RoomEQ) many people espouse a house curve, that is a bump in the low end that rolls off down to flat.

Some people who grew up with bright or forward speakers (Klipsch anyone prefer a bump in the high end too. Its all about personal preference.

IMHO flat speakers are great for classical listening. I prefer a house curve for movie watching. I prefer a smaller house curve for music listening and have a slight bias towards bright speakers overall.

[cjd]

We had been listening for months to a pair of Monitor Audio Silver RS8 speakers, which have a rising FR from 2 or 3 KHz up.

This right here says that your ears are used to one thing and are not hearing that any more. Nothing more.

When you have a bright light shining at you and it's suddenly fixed so it no longer is in your face, your perception is that the room is darker than it really is.

In other words, this is not a fair test to YOU as the listener.

Give them some time. Your ears that is. With the new speakers.

You may go back to the MA's and find they're harsh and unlistenable.

C

[Jim Holtz]

I'd like to know how many people spend lots of money on crossovers making the speakers flat to turn around and mess with the EQ settings just to add or subtract additional response.

How much can the dynamic's of the room really change mid/high frequency output of the speakers.

I'm with AJ and Jon. IMHO, creating speakers that are as accurate as possible is the only way to go and should be a top priority both on and off axis. Why create a design that will only sound "right" on part of the music? If you have recordings that need help, get an equalizer.

I want to hear as close to the original recording as possible. My opinion only, of course.

Jim

Jim

[dlneubec]

My experience with my omni project supports what CJD and John says. I've been voicing/tweaking the crossover and listening to changes for about the last 2 months. I started with a bit hotter top end because the RS28 has sometimes been described as "dull". The tweaks have all been small, but incremental. In that time my ears have adjusted to what is a flatter FR than I had in my previous speakers. I have actually attenuated the tweeter output little by little as time has gone along, toward a flatter response overall. Below is the last on axis measurement of the two speakers I took and I have since attentuated the tweeter an additional .3ohms. Of course my adjustments are also a reflection of adapting the design to in room response, both on and off axis.

It definitely takes your ears some time to adjust to a new speakers sound. I think it is best to listen to a very wide range of material, of all types and recording qualities in that process. I've found that I can now listen to material that I was previously unable to tolerate with my previous speakers.

[kgveteran]

I built three RS WTMW's (center channel) as my mains.They all sit horizontal.After listening and measuring and listening i noticed that the midrange was more forward than I like.I sit rather close (about 6.5'). I then measured the response of my old Paradigm Mini MK3's. I noticed that there was a dip in the response centered about 2khz.The dip was about -3db. I then got out one of my trusty Ashly 66a PEQ's and recreated that same dip in my new RS WTMW across the board.It sounded perfect.I like a laidback midrange.

You could say, why build new speakers, just keep the old ones.They were only twoways and couldn't handle the demands of HT.I am very happy with the new sound of the old monitors.

They call that dip a "BBC" curve.The brits like it too.

[TacoD]

I optimize the off-axis response, sometimes that means the on-axis FR needs 1 - 1.5dB extra output >10 kHz.

[warnerwh]

I optimize the off-axis response, sometimes that means the on-axis FR needs 1 - 1.5dB extra output >10 kHz.

And I like just the opposite.

[cotdt]

... and that's why we all are into DIY. you can tweak the sound to your personal liking.

[JonW]

Sorry to come late to the party (been busy with work). But I also found myself not liking a flat response so much. Details are discussed in the Modula MT thread. And I got lots of help from the folks here about spicing the speakers more to my tastes- which turned out to have a slightly more pronoucned high end. Of the 4 or so friends that got to hear the "flat" Modula MT's compared to the "bright" Totems, all preferred the Totems. Of course, other parts of the speakers come into play there as well.

Some people like what I would call a "HiFi emphasis in speakers, a slight up slope in the treble, such as those Totem Forests JonW has and likes. But I think that's only called for when you're compensating with other issues in the playback system, such as a lack of clarity, or too much of a downslope in power response due to poor off axis response.

Interesting. So now I wonder if, indeed, my system is set up to sound good, but is compensating for something. Any suggestions as to what I should be looking to fix?

And 2 silly thoughts come to mind:
-Did I just ask people to suggest how I can spend more money?:banghead:
-People are always telling me I'm compensating for something.

[ThomasW]

No offense..... but, those not having much exposure to better higher-end systems, will always chose a 'brighter' system as 'better.

It's standard marketing practice to sell systems with more mark-up against neutral systems for just this reason.

Play the bright system, then play the neutral system. The n00b will always pick the 'bright' system as 'better'.

[warnerwh]

I'm surprised I didn't know that. It had struck me as odd.

[ThomasW]

If a store needs to 'move' some product, it's not unusual for them to turn up the treble on the product they want to sell, or turn down the treble on ones they want to keep.

This is but one reason why anything other than an in-home audition is basically worthless.

[JonW]

No offense..... but, those not having much exposure to better higher-end systems, will always chose a 'brighter' system as 'better.

None taken. I'm still at the beginning of this whole audio thing. (No idea where I'll end up). The setup I have at home is actually as high end as anything I've had a chance to listen to at any significant length. When I was shopping for amps, speakers, etc. I never got the chance to listen to anything too far out of my price range. Maybe I should rephrase that: "I never *dared* listen to anything too far out of my price range."

It's standard marketing practice to sell systems with more mark-up against neutral systems for just this reason.

Play the bright system, then play the neutral system. The n00b will always pick the 'bright' system as 'better'.

Interesting. And not surprising. What I found when adjusting the tweeter level on the Modula MT's was that a higher tweeter level would grab my attention and I would like it a lot- for the first few seconds. But even within 1/2 a minute, it might then sound too harsh. So I can see where bright might be attention grabbing and sell well. Especially if you do not get to listen to it for a long time.

[ThomasW]

This is another reason noobs frequently complain about 'bright' electronics. They've actually bought speakers that have a hot top end, and their ears are getting toasted by the speakers. But they assume it's the CD player, receiver or whatever.

If one is educating a n00b, steer them toward the non-intrusive speaker that doesn't "stand-out". Unfortunately that's sometimes a difficult sell....

Interesting it's usually easier for women to accept this idea since their hearing is more sensitive.

[---k---]

Jon,
This place is just down the street from me.

http://holmaudio.com/usedDemo.htm

Good guys. I need to go visit them some more, now that I have a better clue. You shold think about coming back up some time and visiting them.

[ThomasW]

Jon's decided to dive off the deep end and learn how to design speakers from scratch as his newest hobby. We talked at length about this last week when he was in Denver.

Given his Doctorate from MIT and post doctoral work at Cal Tech, I think with time, he's probably trainable toward this end ..... :T

As a result we've been discussing, test equipment, software, and how to go about learning to do this. Only time will tell though if he's as good with speakers as he is with the adhesive properties of mussels...... :B

[Dennis H]

Only time will tell though if he's as good with speakers as he is with the adhesive properties of mussels......

Now there's a subject! Anybody who has ever tried to scrape off barnacles knows their glue is some kind of strong! Read 'em and weep epoxy. I picked up a nice Japanese glass fishing float out in the middle of the Pacific on a sailing trip and I was about ready to shoot the thing with a shotgun by the time I got the barnacles cleaned off.

[crackyflipside]

I can't play my sub flat with the rest of the speakers. 8O

When everythings calibrated flat it sounds so bass-less. I run the bass hot about 3db. I like a flat FR as long as there is a few db's hot in the bass.

[jonathanb3478]

This right here says that your ears are used to one thing and are not hearing that any more. Nothing more.

When you have a bright light shining at you and it's suddenly fixed so it no longer is in your face, your perception is that the room is darker than it really is.

In other words, this is not a fair test to YOU as the listener.

Give them some time. Your ears that is. With the new speakers.

You may go back to the MA's and find they're harsh and unlistenable.

C

I think this principle accounts for way more than it is given credit for. It might be worth while to get the DIY pair (of the OP's) in the "flat" config and run it exclusively for a month or two, then switch back to the MA pair and see...

...just a thought. 8)

[warnerwh]

I'd agree with this last statement. It's surprising how much this phenomena can affect us. Being truly objective isn't as easy as we think it is.

[DougyD19]

After I created my last set of speakers, my wife and I compared them to my old set I had made. At lower volume levels, my old speakers were brighter and seemed to sound better...but only just because it played louder at the low volume level. Once the volume was turned up though, it was a whole different story. My new speakers came alive and were richer and pleasing to listen to even at long durations. The old speakers would hurt the ears somewhat after listening to for long durations. The highs were too high and the mids were not rich.

Interesting it's usually easier for women to accept this idea since their hearing is more sensitive.

This is very true. My wife is more sensitive to highs then I am. My wife hated the old speakers because she thought the highs were to high the whole time, even at low volume levels.

[DougyD19]

I've got another question for you on the HT setup. On the Dolby D setting, doesn't most chip processors in HT Receivers modify the sound signal to where the center channel doesn't play very much highs, but sends them to the front surround speakers.

Does this have to do with sound staging?

[wmilas]

No offense..... but, those not having much exposure to better higher-end systems, will always chose a 'brighter' system as 'better.

It's standard marketing practice to sell systems with more mark-up against neutral systems for just this reason.

Play the bright system, then play the neutral system. The n00b will always pick the 'bright' system as 'better'.

This is not 100% true, as far as the noob goes. I've owned and loved Klipsch for years. Being horn loaded, they are bright. I love the sound. I've become accustomed to it over 15+ years and well, its addictive. Its just a personal preference, neither good, bad, or noobish. I've also owned KEF gear during the same time that are almost totally neutral. I love the KEF on classical non vocal pieces where the Klipsch can sound harsh. The monster soundstage, and for a better lack of description, volume of say my Chorus II's are truely addictive to me.

The main reason I started reading this forum was to reconcile these two aspects. The idea here is to learn exactly why I like what I like, how to model it, and how to build a flat speaker and possibly adjust the crossover to model this sound in different ways. Not likely, but an interesting exercise.

[wmilas]

I can't play my sub flat with the rest of the speakers. 8O

When everythings calibrated flat it sounds so bass-less. I run the bass hot about 3db. I like a flat FR as long as there is a few db's hot in the bass.

Thats a standard house curve assuming you have some sort of rolloff before 80ish hz. Most non audiophiles, and alot of audiophile from my personal observations prefer this for movies, and most music.

[JonW]

Jon,
This place is just down the street from me.

http://holmaudio.com/usedDemo.htm

Good guys. I need to go visit them some more, now that I have a better clue. You shold think about coming back up some time and visiting them.

Interesting. Maybe the next time I'm in town, we could both stop by. Chicago actually has a lot of high end audio shops. I've only been to a couple.

Probably a topic for private email, but I'm wondering what you have in mind for your next project. Because it would be close enough for me to hear it when it's done. :B

... I think with time, he's probably trainable ...

I live with a gal who might differ. : :B

[warnerwh]

"I live with a gal who might differ. "

Get back to us in a couple of years. :rofl:

[fjhuerta]

This is another reason noobs frequently complain about 'bright' electronics. They've actually bought speakers that have a hot top end, and their ears are getting toasted by the speakers. But they assume it's the CD player, receiver or whatever.

That'd definitely explain why I went crazy over the Monitor Audios when I first listened to them, and why, over time, I wondered why I actually preferred my (waaaay cheaper) Energy Connoisseurs (which may be cheap, but damn, they are quite flat when compared to the MA's).

It definitely works like that. Now I dislike the Monitor Audios. I got used to my speakers. I did lift the top end by 1 dB or so and fixed a couple of issues with baffle step (there was about 1.5 dB too much of it).

But hey, there's another idea now... I can modify the MA crossover... although I'm not so sure this would be a good idea. The tweeter has a nasty, nasty resonance at 20 KHz or a bit less. I guess it'd melt your ears anyhow

Thank you all so very much for teaching me what I was aching to learn. :T