Re: Recommended reading for EQ

Randy54 wrote:

Here's a sweep from 20-20kHz with 1/3 smoothing. There is a graphing artifact at the left. In the 10-200Hz plot, the signal doesn't rise as it appears to in this plot. The same artifact is present in the paired plots posted previously.

https://www.eldoradosoft.com/images/audio/sweep11.png

Looks quite nice for no EQ at all. This is all from speaker placement and acoustic treatment.

Thanks
But to me it still looks weird. Is it possible to go in the main view of rew where the curve is and click in the right bottom corner and click on the 20-20000?
This gives a more detailed view through to 1000Hz and then goes more rapidly to 20000Hz.
But you will get great advice here. And it seems like you are pretty advanced in this stuff. So everything will be good.
Congrats on the RME and also at the great gear you have.

502 (edited by Randy54 2019-12-22 03:22:12)

Re: Recommended reading for EQ

Is it possible to go in the main view of rew where the curve is and click in the right bottom corner and click on the 20-20000?

That's what you are seeing. Look at the X axis... 20Hz -> 20kHz.

Congrats on the RME and also at the great gear you have.

Thank you!

Re: Recommended reading for EQ

Are you perhaps thinking of the logarithmic plot?

504

Re: Recommended reading for EQ

Randy54, very nice post! I am sorry but have to comment on a few things as you mixed up different things.

Randy54 wrote:

I'm thinking that people are confused because they often hear that low freqs are not directional. That isn't really true.

It is true.

Randy54 wrote:

The two stereo signals arrive at our ears at different times

You do not sit in a triangle setup to your speakers? Otherwise they do arrive at the same time. Due to the big wavelength in bass even the distance between left and right ear is irrelevant.

Randy54 wrote:

with different information regardless of frequency. There's no reason to believe that somehow low freqs don't contain phase information.

Nobody claimed that they don't.

Randy54 wrote:

At what frequency would the phase information disappear?

That's not the point. The point was about audibility of such phase information on a typical home stereo setup, plus the fact that most home systems these days use a single subwoofer.

Since home studios have taken over the world of music production, stereo bass is no longer red tape. It is used by some artists/musicians/producers to widen the sound also in the deep end. The only way to enjoy such audio in its full glory is by using headphones. Room acoustics are mostly terrible at lowest frequencies (we are talking below 80 Hz here), and combined with missing directivity at those frequencies mangle any low bass stereo phase into a simple mono amplitude (level) modulation at the listener's position.

Regards
Matthias Carstens
RME

Re: Recommended reading for EQ

Bliman, here's the logarithmic plot. The peak 30-55Hz is quite audible. I had a shelf filter in MC25 set up for 45Hz and below. That evened it out nicely; I like a lot of bass. Was just chilling with Billie Eilish - how did she get such good production at age 17???

I wonder if dispersers at the FRP and SRP would help the 5kHz-20kHz range? The down comforter probably absorbs high freqs. I didn't get to make the BAD Panels due to the early arrival of R.E.M.  Oops, RME.

https://www.eldoradosoft.com/images/audio/sweep12.png

Re: Recommended reading for EQ

Vielen Dank, Matthias. I suppose the theoretical and the realistic aren't always the same. I understand where Bejoro is coming from, though. He made sense to me; I'm glad you posted this information.

Randy

Re: Recommended reading for EQ

Just in case we are confused, bejoro was discussing a system with two subs configured as mono. Stereo seemed to make sense in that situation.

Re: Recommended reading for EQ

Randy54 wrote:

Bliman, here's the logarithmic plot. The peak 30-55Hz is quite audible. I had a shelf filter in MC25 set up for 45Hz and below. That evened it out nicely; I like a lot of bass. Was just chilling with Billie Eilish - how did she get such good production at age 17???

I wonder if dispersers at the FRP and SRP would help the 5kHz-20kHz range? The down comforter probably absorbs high freqs. I didn't get to make the BAD Panels due to the early arrival of R.E.M.  Oops, RME.

https://www.eldoradosoft.com/images/audio/sweep12.png

That's the one. Thank you

509 (edited by Randy54 2019-12-22 04:20:18)

Re: Recommended reading for EQ

Otherwise they do arrive at the same time.

Another thought. If a sine wave is recorded equally on both channels, yes, the signals will arrive simultaneously. Let's now envision a two-mic stereo recording. The sound from an instrument on the right side of the orchestra will reach the right mic before the left. When played back, the signal of the instrument should emerge from the right speaker first, reaching the right ear first - presumably with the same arrival times for each in a good setup.

When the original signal reaches the left mic, it will be in a different phase than the signal received by the right mic. This phase information is part of the soundstage reconstruction.

Now let's hit a timpani on the right side of the orchestra. Even though it has low frequencies, they will arrive at the right mic first and the left second. There will be less phase difference due to the low frequency, but there is a phase difference of some size and definitely a time delta, since all freqs move at the speed of sound. I imagine that bejoro (auch ein Deutcher) was thinking analytically as am I.

But you have got me wondering what exactly is the phase relationship of the two mics in the timpani situation. I'd like to generate a (off-axis) sine wave burst of 25Hz and compare arrival times and phases.

Re: Recommended reading for EQ

Randy54 wrote:

Bliman, here's the logarithmic plot. The peak 30-55Hz is quite audible. I had a shelf filter in MC25 set up for 45Hz and below. That evened it out nicely; I like a lot of bass. Was just chilling with Billie Eilish - how did she get such good production at age 17???

I wonder if dispersers at the FRP and SRP would help the 5kHz-20kHz range? The down comforter probably absorbs high freqs. I didn't get to make the BAD Panels due to the early arrival of R.E.M.  Oops, RME.

https://www.eldoradosoft.com/images/audio/sweep12.png

To me, it looks like a nice stable curve but I wonder how you would perceive it if the curve was more elevated between 60Hz and 600 Hz and a little down on 1Khz.
You can always play with EQ to see if it changes your perception. You don't lose anything to try it.
Or else try to tame the range between 1K and 5K.
But if I was you I would try different things, measure and evaluate with REW and your ears.

511 (edited by Randy54 2019-12-22 04:14:48)

Re: Recommended reading for EQ

I wonder how you would perceive it if the curve was more elevated between 60Hz and 600 Hz and a little down on 1Khz.

I expect it would be more pleasant than it is now. Curt has warned me a number of times about boosting frequency ranges, so this could be approached by lessening the 20-50Hz hump as well as the 600-2000Hz range (EDIT: you suggested this; I forgot while I was writing). However, Curt is currently flying Not A Max and won't be around to chime in until later.

I need to move the Display Case before I get serious about EQ. It's all glass exactly at the FRP as well as the SRP. When that gets moved to another location and the down comforter is out of the equation, I can tame the FRP and SRP, then go about a proper EQ methodology.

512 (edited by Randy54 2019-12-22 06:31:14)

Re: Recommended reading for EQ

Matthias got me thinking. I wanted to find the time and phase delta between two microphones in the thought experiment of a timpani in an orchestra. Here's what I found:

              https://www.eldoradosoft.com/images/audio/stage.png

Although I found that a typical timpani tuning is C3 (130.8 Hz), this study sticks with the very low frequency of 25Hz just to learn its timing.

The arrival times of an off-axis signal at two microphones will always be different, based on the angle from the axis and the separation of the mics. The frequency doesn't matter, as all freqs propagate at the speed of sound, 343 m/s. It could be a flute in the back-right corner; the arrival time delta of 0.635ms will be the same.

In this example, the mics are 0.5m from each other, directly behind the conductor as typical. It turned out that, even at 25Hz, there is a phase difference of 5.715 degrees between the right mic and the left. The phase difference will vary based on the frequency, but the arrival times won't.

We can tell what direction thunder comes from. I respectfully submit that delta-time and delta-phase are both processed by our brains to form directionality and soundstage regardless of frequency. I'll sign up for the dirtiness of the typical listening room and the pollution it causes, but both off-axis deltas are non-zero. I also expect that a real-world experiment would notice the direct-path wavefronts from the subs and register the delta-time/phase as illustrated. What follows depends on the room and its reflections, but I'll still support bejoro after this analysis. Everything my engineer's brain sees tells me that two subs running stereo will add soundstage compared to two subs running mono.

Everyone who loves math, please jump into the discussion. There's math and there's reality; the two need not coincide in this situation.

Randy

Re: Recommended reading for EQ

How does one know that an ADI-2 makes good sound?

I played my favorite 10 or so Crystal Method songs with 4 dB bass boost. Sound level was at -11 dB - I don't know about your system and setting, but things here were rattling. A saying about the #331 at the time, when people asked about "only" 100 watts: "It's 100 watts into any impedance, any frequency from DC to daylight". The RME brought out the best of it and the speakers.

The music ended. I looked at the clock, 10:30, later than polite for such behavior. I dialed it back and turned on Pink's Greatest Hits. She wasn't there! The soundstage was destroyed!

The right speaker had walked over 5 degrees off-axis. A half-dozen rocks and meteorites walked around the display case. I hadn't thought about that... if glass is rattling, rocks can walk. I worked the speaker back into place, half cussing the re-alignment time, half smiling at the pleasure of it all. I need to put something under the feet of the NHTs, as this isn't the first time the right one walked. However, it was the farthest it walked! smile

Indeed, this is a very fine product that I've just begun to explore. Thank you, RME! Wunderbar!

514 (edited by bejoro 2019-12-22 09:26:51)

Re: Recommended reading for EQ

@Randy54
Thank you for your e-mails. I answer only in this thread again because you pointed me directly to your findings in this thread and I do not want to be impolite.

Already 25 years ago, after many comparing listening tests with many recordings I could definitely and easily prove that one subwoofer is not enough for a serious stereo setup, you will lose the phase information that is included in many recordings and that is clearly audible.

The shocking part was that this is absolutely not a subtle effect, as I proved in this thread with one example of Sara K.'s title "Water Falls" (CD and SACD release). Stockfish, Chesky, Reference Recordings and other professional recording studios confirmed my findings; they always use/recommend 2 subwoofers for a stereo setup or of course just good full range speakers with optimized positioning and room treatment.

As mentioned before, for home cinema and its separated (mono) LFE channel one subwoofer is common and suitable. So it is a misconception that one subwoofer is enough for 2-channel (stereo) music listening (and recording).

Warm regards,
Bernhard Rother
enjoy-audio.de

515 (edited by Curt962 2019-12-22 14:37:56)

Re: Recommended reading for EQ

Wow!   While sealed in a pressurized Alumimum Tube,  I missed a LOT of activity!!

Randy, so it seems you reallly enjoy your new ADI-2.DAC.  smile     We might have predicted this outcome, as it IS indeed a Superb piece of engineering.

Walking Speakers, and Moon Rocks!   That was a unique Twist none of us could have anticipated!   smile   Especially  at 0600, with only a SIP of Coffee!    How is your Home Constructed?   Frame, Etc?    It is remarkable that gear CAN MOVE, and in some cases there will be a large amount of energy transferred into the Structure, and this is when China Cabinets rattle, and sing, and a Stainless Steel Sink in an adjacent Space drums along like an uninvited Percussion Section.  Imagine if we could isolate the Stimuli from these other noises and just LISTEN to the Commotion!!   It would be amazing.    These are sound "pollutants" in the Room that must go.   A means of Mechanically Decoupling the Speakers/Subs from the Room structure can be helpful.   I dislike using this thread as an advertising platform, but there are several products out there that might be useful to You in addressing this matter.

* SVS "Soundpath" Isolation Feet.   These things KILL energy transfer.   They've been under my Subs for years.

https://www.svsound.com/products/soundp … ion-system

* Auralex "Sub Dude"    Not as Sexy, but still quite effective.   

https://www.auralex.com/product/subdude-ii/

Did I mention Subs?   Dual Subs for me thank you!   It DOES impact Soundstage Size, plus...Lower Distortion, Higher Headroom, and overlapping Modal Behaviors in the Room that makes it easier to achieve a Uniform Room Response. 

Now where's that Coffee....

Curt

Vintage 2018 ADI-2 DAC. "Classic Edition"
Cables:  Red Ones, and White Ones.
Speakers:  Yes (2)

516 (edited by Curt962 2019-12-22 16:28:39)

Re: Recommended reading for EQ

Randy54 wrote:

Curt has warned me a number of times about boosting frequency ranges, so this could be approached by lessening the 20-50Hz hump as well

"Curt" just gets a little uneasy with certain approaches to EQ.   Boosts in particular, as they can put Expensive Speakers in Harm's Way.   That 10ish db bump at 35-40hz is 100% Modal in nature, and correlates well to a 14-15ft Rm Dimension.   A bit of PEQ CUT centered on that Peak would tame it nicely!

We don't want 10db peaks/Nulls,  but I might discourage against striving for a Ruler Flat Room Response.   This almost invariably results in the listener believing the SQ is just too dry, and lifeless.   As mentioned to Bliman in an earlier Post, It's this "Dryness" that gave rise to "Harman Curves"    The Studies conclude that us Humanoids do prefer a bit FULLER sound.

Fun Fun!

Curt

Vintage 2018 ADI-2 DAC. "Classic Edition"
Cables:  Red Ones, and White Ones.
Speakers:  Yes (2)

517 (edited by Randy54 2019-12-23 05:14:46)

Re: Recommended reading for EQ

Indeed, Fun Fun!

Already 25 years ago, after many comparing listening tests with many recordings I could definitely and easily prove that one subwoofer is not enough for a serious stereo setup, you will lose the phase information that is included in many recordings and that is clearly audible.

@bejoro... clearly, you and Curt have exquisite listening environments. Matthias politely wrote me off-list so we could delve into this more deeply. I know that the math is correct; in fact, Matthias sent me calculations he performed differently that me, showing the phase difference between channels. Nonetheless, he expressed concern that the typical listening environment is too polluted with reflections for these to be noticeable. He encouraged me to experiment and find the answer for myself.

Today I wrote a C++ program that generates WAV files containing a sine wave that alternates from 75 degrees right to 75 degrees left. At first, I forgot to include the inverse-square volume difference between stereo microphones while recording, so the soundstage was not optimal. When that was added, I clearly heard the direction of the alternating source on my dev system in the office (filled with shelves full of books, the old "bookcase disperser" concept).

I went to the the listening room, played the WAV files through the REM/Levinson and was shocked. The clear directionality I heard in the office had vanished. I was disheartened. I put the comforter back over the display case to no avail. I shortened the pulse and heard a very clear echo in the listening room that I'd never heard before.

It seems that Matthias and I were both correct, although Matthias is correct far more frequently than I am. When I came here to post this, I was surprised to see bejoro's post, followed by Curt's. Both of your *hear* the difference. I didn't. I wanted to (and did in the office) but did not hear it in the listening room.

I want to let people know that Matthias had valuable insight for us. Bejoro and Curt are on the right end of the bell curve, and despite my desire to hear what I heard in the office, it isn't there in my listening room.

Thank you, Matthias, for your polite discussion with me on this topic. I know now that you are right in 99% of situations. OTOH, bejoro and Curt know their own ears and the math backs them up. I agree with you in general and wish I had an environment where I could hear what these two hear.

It was a pleasant exchange, ending in a demonstration of the wisdom of your words in most situations. Thank you again for sharing with me and helping me understand!

Randy


https://www.eldoradosoft.com/images/audio/DeerOnIce.png

518 (edited by Curt962 2019-12-23 17:01:20)

Re: Recommended reading for EQ

Randy, Bliman,etc, et al

Fine Contributions!  Thanks!    That is precisely what this Thread is all about. 

On LF "directionality" matters however, my Hearing is NOT exempt from the Laws of Physics.   Consider for example that a Bass Instrument does not emit a pure tone (usually) . Especially so if I'm Playing!  It's The initial Transient... The Mallet strike on a Timpani is rather High Frequency.   Readily Localized by the Ear/Brain.   The LF fundamental tone which immediately follows has a Wavelength MANY MANY times larger than distance between our Ears.    Phase/Amplitude differences: Left Ear/Right Ear is virtually Nil.      It was the Mallet Strike that gave its location away...not the 25hz tone that followed.  smile

It's all an enjoyable, civilized discussion that we want to keep going!    Manoman...within 24hrs, your 60hz Null VANISHED.  Total Cost:  a 14 inch movement of your Listening Chair.    That's a fantastic deal, and what other Forum on Earth can upgrade your sound On-Line? smile

Great Stuff!  Thanks to all for taking part in the Fun.

Curt

Vintage 2018 ADI-2 DAC. "Classic Edition"
Cables:  Red Ones, and White Ones.
Speakers:  Yes (2)

Re: Recommended reading for EQ

I am very grateful for the help and camaraderie shown on this forum, and especially for your spot-on advice.

Thanks for the timpani thoughts. Last night, falling asleep, I wondered if the location would be more apparent with a more realistic envelope, such as a note on a xylophone. My tests were at 440Hz - given your thoughts, I'd like to experiment in the kHz range to learn more. Can't try it today, I write a model railroad CAD program and it's That Time of Year.

520 (edited by Curt962 2019-12-23 19:02:45)

Re: Recommended reading for EQ

Satisfaction is our Game.   Glad you joined in Randy! 

Curt

Vintage 2018 ADI-2 DAC. "Classic Edition"
Cables:  Red Ones, and White Ones.
Speakers:  Yes (2)

Re: Recommended reading for EQ

Randy54 wrote:

I am very grateful for the help and camaraderie shown on this forum, and especially for your spot-on advice.

Thanks for the timpani thoughts. Last night, falling asleep, I wondered if the location would be more apparent with a more realistic envelope, such as a note on a xylophone. My tests were at 440Hz - given your thoughts, I'd like to experiment in the kHz range to learn more. Can't try it today, I write a model railroad CAD program and it's That Time of Year.

You most probably know this. But you will never know.
If you are interested in loudspeakers and rooms and much more then this is a must.
If you don't have it then treat yourself for the holidays
https://www.amazon.com/Sound-Reproducti … TG5TCM4ZN6

Re: Recommended reading for EQ

Great Recommendation Bliman.   Knowledge is Power!!

Curt

Vintage 2018 ADI-2 DAC. "Classic Edition"
Cables:  Red Ones, and White Ones.
Speakers:  Yes (2)

Re: Recommended reading for EQ

What a good book! Thank you for letting us know!

I'm having a crazy good time with these waveforms, and learned interesting things. Most of all - our brains are really smart processors of limited information. Get this: with the new wave envelopes, the 440Hz tone very clearly shifts L/R. At 880Hz, it's virtually centered.

For sure, Curt and bojoro are correct about the power of phase. My listening room has some terrible problems that curiously go unnoticed with music rather than a sine wave. It's like sonar with these pulses... DING-ding, DING-ding, DING-ding.

Anybody know what that measurement of decay time in ms is called, and what's a good value?

https://www.eldoradosoft.com/images/audio/440Hz.png

Re: Recommended reading for EQ

Randy,

That measurement is most often thought of as "RT60,.etc"

Reverberation Time elapsed until the Signal Level has decayed 60db.   Also expressed as RT20, etc.  You get it.

Much of the Science relating to "optimal" decay times was developed for Churches...Cathedrals. Large Venues, etc and has little relevance in our Comparatively  Tiny Rooms.

Vintage 2018 ADI-2 DAC. "Classic Edition"
Cables:  Red Ones, and White Ones.
Speakers:  Yes (2)

Re: Recommended reading for EQ

Exactly! Along with the history - you're a knowledgeable man, Curt! Thank you...

My RT60 would be about 250ms, just guessing. I could record it and check.

526 (edited by Randy54 2019-12-24 07:53:16)

Re: Recommended reading for EQ

Mathematics is not necessarily congruent with Reality.

This shows a 440Hz pulse whose source location shifts L/R like a stereo sonar. On top is the stereo signal generated by the program. The L/R shift is seen here by its amplitude (the phase can only be seen when zoomed in more closely). What's important is that the right speaker (top) is louder first, then the left, and they are L/R aligned with the real-world results. The timing scale is a bit off; you can ignore it as an artifact of aligning the image widths.

At the bottom are two recordings on the UMIK in my music room. I'm so conflicted. In every way, before the last couple days I've considered this house to be the very best listening environment this stereo ever graced. There are two mono plots in the lower half: the top of the lower pair is with the display case and the wine cooler uncovered. The bottom plot is after putting the Comforter of Down over the display case and pillow-shielding the glass on the wine cooler.

I can't believe how much this signal is convoluted! As far as Curt's warning to just GET YOUR GLASS OUT OF HERE goes, the top mono plot shows the signal ringing on until the next one comes. The bottom plot actually gets quiet.

This is surprising, informative and challenging. Curt... you told us how you fought to tame glass furniture in another room. I get it.

https://www.eldoradosoft.com/images/audio/Results1.png

How can the system have such a detailed soundstage and sound so good with this kind of distortion? Fascinating.

[EDIT} The bottom-most graph was at 1/2 zoom compared to the one above it. The signal was not more quiet as it appears in the image. SNAFU

Re: Recommended reading for EQ

Something magic is happening. Has anyone else experienced this? The ADI-2 has been here two days, turned on about 28 hours (no signal through the night). Not knowing what to play next, I turned on ALT-AZ 93.3. Sangean HDFM, RME ADI-2, Levinson 331, NHT 3.3. The ADI-2 is the newcomer.

I can't even express the tangible, visceral, fluid, glistening sound I'm hearing. Nothing has changed since repositioning the speaker that walked, but the electronics is settling in. What I'm hearing is beyond any sound I've experienced, ever. Holy cow! I'm being pulled out of the office yet again.

Back after a few minutes. "Smile for the Camera" was playing, a new song to me. The sonic image had improved even more. I was hypnotized. I moved around naturally and the soundstage was rock solid. My previous post shows the distortion in the room, but the sound is captivating. How can this be?

Matthias, +1 for you.  smile  Math approximates reality.

Vielen Dank, RME!

528 (edited by Curt962 2019-12-24 16:21:47)

Re: Recommended reading for EQ

Wow Randy, seems you were quite busy posting whilst my Lazy Self was sleeping.

How is the Ear/Brain able to re-construct a intelligible stereo image, or sound amidst an onslaught of conflicting information?   That's a Deep Science, and suggests the Ear/Brain is a highly evolved Data Processor with well developed Discriminator, and Filter "Circuits" that make Order out of Chaos*

My Own Peer Reviewed (Neighbors) Research as a Parent has concluded that this Discriminator/Filter system is most highly developed in Teenagers, whom with great Scientific Certainty, will hear ONLY what they choose to hear!  smile

   Alas, It's the same system that allows us to converse amidst the Acoustic Chaos of a Noisy City Street, while still able to receive, and respond to the Aural warnings of a rapidly approaching Bus!!    In this case, the Audiophile would surely be struck, and killed as he remained in the Street debating if the Wailing Bus Horn sounded a bit "Boxy", or the Roaring Engine seemed a bit "Bloated"

"Geez Randy, those Screeching Tires are REALLY DYNAMIC, but they sounded far more Buttery last time I heard this..."

Boom!

The Ear/Brain.  Think of it as a Survival Tool for the rest of us  smile

Curt

PS:  Your ADI-2 DAC is exactly the same as the moment you unboxed it.    You're Excited, making changes in the Room, and Very Focused upon the composite result.
The RME will always facilitate your ability to achieve great sound, but itself never changes.  No Metamorphosis has occurred deep within..."It jus' dint" as they say here...

Your  ADI-2 has no "Break in"   That whole concept applied to purely electronic, modern device is simply not factual, and would swiftly die a horrible death in these pages. smile  So..."let's not go there"  ')

Best Regards, and Merry Christmas!

Enjoy your new ADI-2 DAC!

Curt

Vintage 2018 ADI-2 DAC. "Classic Edition"
Cables:  Red Ones, and White Ones.
Speakers:  Yes (2)

Re: Recommended reading for EQ

Then I will indulge in my own delusion, enjoying every moment while knowing a bus can't possibly reach me.

Merry Christmas to you and everyone here.

Re: Recommended reading for EQ

Hi Randy!

Indulge!!   Enjoy your new RME, and be Happy knowing that it will be a Supremely Strong, and Stable Platform with which to build upon.   Me Tinks (Island Speak) that you are hearing the impressive Clarity of your ADI-2, so by all means...ENJOY!!

I AM!!  My Christmas Vocal Ensemble/Choral Music Collection is in Heavy Rotation, and in Full Bloom!! 

Fröliche Weihnachten zu Alles!!

Curt

Vintage 2018 ADI-2 DAC. "Classic Edition"
Cables:  Red Ones, and White Ones.
Speakers:  Yes (2)

Re: Recommended reading for EQ

Howdy Curt,

Good news! The HDFM really did sound better! When I played music through JRiver MC25, it sounded hollow. Through the headphones the tone was centered, as was Lady Gaga. Somewhere along the line, MC25 was hooked to the RME Analog driver, not ASIO. That turned it into a mono signal! When I switched MC25 to ASIO, the same wonderful sound came alive!

The program now builds 96kx32 files. The L/R pattern is clear and cleaner at the higher bitrate and sample width - at 440Hz. The waveforms aren't mangled any more... they reflect the nature of the room. Right channel is first in the plot; comforter is in place. More exploring later.

Thank you, Curt. I took your advice on "breaking in" as gospel and looked elsewhere. Success!

Prettige Kerstdag en een gelukkig nieuwjaar voor iedereen!

https://www.eldoradosoft.com/images/audio/440Hz-96-32-r1.png

Re: Recommended reading for EQ

Ah... resolution of contradictory input. Matthias said that we can't determine direction to low freq sources. Bejoro and Curt definitely hear low-frequency phase differences. I mentioned that we can tell where thunder comes from. It's all consistent, at last. Low freqs *can* have location information, under the proper circumstances.

https://www.soundonsound.com/techniques … udio-files

"If the time‑of‑arrival mechanism relies on transients, and transients fundamentally comprise high‑frequency sound elements, how do we locate low‑frequency sound sources? Well, the phase difference between sounds arriving at each ear is used for this. The size of the average head means that phase differences become ambiguous above about 2kHz, because the path length around the head produces phase shifts in excess of 360 degrees — in a relative phase difference of 20 degrees is indistinguishable from a relative phase shift of, 380, 740, or 1100 degrees — but these absolute phase differences imply very different source bearings. However, for low frequencies the wavelength of sound is so long that the path length around the head becomes insignificant and phase shifts become a meaningful way of measuring source location.

However, within a closed environment like a typical project‑studio control room, LF reflections and standing waves within a room create additional phase differences between the ears which vary unpredictably. As a result, the multitude of contradicting phase shifts makes it impossible to determine the bearing of a low frequency sound source with any accuracy. So whereas it is possible to detect the direction of a low‑frequency sound source out of doors, it is almost impossible indoors — and that can be used to advantage, for example, in placing a sub‑woofer as part of a 2.1 monitoring system: in effect, the subwoofer can be located virtually anywhere in the room, with no detrimental effect on the stereo sound stage."

533 (edited by Curt962 2019-12-26 14:06:29)

Re: Recommended reading for EQ

Randy, before we get into treacherous waters, it's perhaps good for you go back a few posts, (post 518) and see what I REALLY said about LF directionality cues.  The Science to which MC subscribes is factually correct.

Curt

Vintage 2018 ADI-2 DAC. "Classic Edition"
Cables:  Red Ones, and White Ones.
Speakers:  Yes (2)

Re: Recommended reading for EQ

I'm sorry, Curt. I don't want to enter treacherous waters after only a few days of discussion. I thought my previous post supported MC's position as well as the experience of you and bejoro. It's been enlightening for me to learn about the role of phase that bejoro mentioned halfway through this thread. However, I have no idea why I chose to bring up the topic again on the forum and apologize to all if I've unwittingly caused concern.

Re: Recommended reading for EQ

No Problem Randy!

It is our Goal to maintain this Fine Thread started by Sparkydude nearly 6 months ago  as a Helpful Resource for both RME Users, and Passerby alike.  This Goal is best achieved by Self-Policing, Maintaining our Focus on Topic, and Ensuring that we keep things Factual.

Our Track Record thus far is Quite Good!

Best,

Curt

Vintage 2018 ADI-2 DAC. "Classic Edition"
Cables:  Red Ones, and White Ones.
Speakers:  Yes (2)

536 (edited by Curt962 2020-01-25 03:38:39)

Re: Recommended reading for EQ

With so many new users appearing on the Forum...

We're still open for business here!    The Speaker/Room interface remains the Final Frontier! 

We can help you improve that, and extract the BEST from your new RME!

Who's up next?

Curt

Vintage 2018 ADI-2 DAC. "Classic Edition"
Cables:  Red Ones, and White Ones.
Speakers:  Yes (2)

537 (edited by Curt962 2020-02-27 02:41:17)

Re: Recommended reading for EQ

Wow.  It sure got quiet here, while knowing that there are at least TWO (2) Users with New, and as yet Un-Ordained "RME READY" Speakers!  smile

https://m.youtube.com/watch?v=KS6f1MKpLGM

Just a gentle "Bump" smile

Curt

Vintage 2018 ADI-2 DAC. "Classic Edition"
Cables:  Red Ones, and White Ones.
Speakers:  Yes (2)

538

Re: Recommended reading for EQ

If it can help, a very nice article about bass management in the room.
With a nice calculator to figure your room out.
https://www.sonarworks.com/blog/learn/i … -the-bass/

https://www.sonarworks.com/blog/wp-content/uploads/2020/02/Axial-Standing-Waves-1.png

ADI-2 DAC (with stock PSU) - Neumann KH 310 A monitors - Cheap USB and XLR cables

539 (edited by Curt962 2020-03-10 19:08:15)

Re: Recommended reading for EQ

Monsignor N00b!   Merci Beaucoup!

That is a Wonderful Visual represemtation of what REALLY happens/   I've done the Math.   Noobs contribution is 100% BS-Free!!

Excellent!!

Curt

Vintage 2018 ADI-2 DAC. "Classic Edition"
Cables:  Red Ones, and White Ones.
Speakers:  Yes (2)

Re: Recommended reading for EQ

Curt962 wrote:

Fisico,

I'm seeing some HUGE BOOSTS on your EQ in the Gear Rack.   That's scary to me, but I might be able to help you fix that...at NO cost, and let you have lower distortion, and more amplifier headroom thrown in!

I'd like to ask for some Room dimensions...Seating Location...Speaker location...in terms of numbers.   

Let's take OUR Chat to the "Recommended Reading for EQ" thread.   I think You, and I can give your System a massive upgrade!  All this...at no cost to you!  I've only had one user injured while moving heavy speakers, and furnishings.  Whatever...  It's a Numbers Game.   Somebody has to get Hurt.  Things happen.  smile

https://forum.rme-audio.de/viewtopic.php?id=29041

Best!! 

Curt

Hello Curt,

Thanks for your kind offer! I will write some more detail to you later.

GT

541 (edited by Curt962 2020-04-19 19:55:53)

Re: Recommended reading for EQ

OK!   Sounds like a Plan!

In spite of all current events, I'm open for Business!   At present, I'm on assignment in the Caribbean.   Maybe our Time Zones are wildly different, but Trust that I want to lend you a hand, and will do my best!!

The Objective is for you to find an even greater appreciation of your RME!    DUDE!   This thing is High Class!!

Curt

Vintage 2018 ADI-2 DAC. "Classic Edition"
Cables:  Red Ones, and White Ones.
Speakers:  Yes (2)

542 (edited by fisico 2020-04-20 00:53:27)

Re: Recommended reading for EQ

Curt962 wrote:

OK!   Sounds like a Plan!

In spite of all current events, I'm open for Business!   At present, I'm on assignment in the Caribbean.   Maybe our Time Zones are wildly different, but Trust that I want to lend you a hand, and will do my best!!

The Objective is for you to find an even greater appreciation of your RME!    DUDE!   This thing is High Class!!

Curt

I'm back!

Let me first say that I guess you are a generous person and I would like to know you in person. By the way, if I read 962 as your birth year correctly, I was born in 1960, so we could be close in age.... On another item, well, the Caribbean is not the worst place to be quarantined in these days, isn't it?

About my system room eq. let me explain some basic facts before tuning up further together the set-up. I am a physicist, so I know in great detail everything about waves in general, closed-boundary acoustics, standing waves, reflection, diffraction, interference and whatever else is scientifically known about sound transmission between sources and detectors, be them ears or microphones, in any given propagation space.

Speakers are the B&W 800D2, remarkably flat in frequency response but a difficult load to drive. That's why as a power amp I chose a Classé CA-2300, with its 0.015Ω source impedance (!), measured at 2x300W on 8Ω, 2x600Ω on 4Ω and 2x1200Ω on 2Ω (!).

The room itself is a difficult environment, because it is very tall and as such there is still a relevant naked surface area, even if I have large absorbing and/or diffractive pieces of furniture, a fireplace, a slightly tilted wall, a recessed window and a vaulted ceiling, all contributing to deviations from the "nude rectangular box" nightmare. Approximate dimensions are 6.6 meters length, 4.5 meters width and 5.5 (at the top) meters height, 1m solid brick walls, built in 1765.

Of course, for the best possible acoustics I should first put in place a thick absorbing false ceiling, but I don't want to hide the precious 18th century fresco on the ceiling which I recently have had carefully restored in the house.

https://i.imgur.com/q7HbB6d.jpg

In order to get the best possible sound out of this room and that equipment, I first played a lot with careful placement of the speakers and the listening position. I spent a long time moving the speakers and the sofa around, sometimes by large amounts, sometimes by very few centimetres, each time measuring the frequency response with an MiniDsp umik-1 microphone and using the REW software, but mostly listening for days and days to all the music I like most and know better.

Once the geometrical problem was stabilised, I started playing with equalisers. I tried digital ones, included the RME ADI-2 DAC 5-band, analog parametric ones and analog graphic ones. I ended up choosing an analog graphic equaliser placed in the tape monitor loop of my preamplifier, because 1) it allows me to room correct any source, both vinyl and the digital ones 2) when listening to vinyl I have a full analog chain, equalisation included, without any AD/DA conversion 3) it allows me to switch immediatly between equalised/not equalised with a touch on my preamp remote 4) because I am an old fart and that's the old way, well known to me, to accomplish the task.

As far as the quantity of the boost is concerned, it is not huge at all. My graphic eq which you see in the pictures is operated at +/-6 dB full scale. In its current set-up, 52 out of 60 sliders apply a correction of less than 3dB. The one and only big correction is a notch filter (very narrow, included in my equaliser) at 32Hz to dampen the vertical fundamental frequency of the room.

You can see the end result in the following picture:

https://i.imgur.com/910ZPJ8.jpg

The purple line is the system frequency response without equalisation and the green line includes equalisation. Both channels summed and smoothed at 1/3 octave. There are still small bumps at 50Hz, 300Hz, 1.25kHz and 8-10kHz. I could kill them with the sliders, but I tried to do so one by one and still my ears tell me it's preferable to keep those small irregularities instead of flattening them.

What I got is a frequency response close to a smooth curve within 1 or 2 dB from 25 to 12.5k Hz, and not "any" smooth curve but what my ears feel to be the most neutral one in my room, by applying +/- 3dB correction MAX on 87% of the sliders, +/- 1.5 dB correction MAX on 50% of the sliders.

Of course I am always ready and willing to experiment and learn whatever possible improvement any idea or piece of gear can bring to my listening pleasure, so if you have something to suggest me you are more than welcome.

And I agree with you, The RME ADI-2 DAC is high class indeed! A great all-around tool to enhance music enjoyment and tuning. I have often played with the in-built equaliser to understand how far or how close I was to my target because the continuous frequency and Q-value regulations offer real-time checks on f.r. adjustment impossible with the graphic tool. The RME is both a pleasure to listen to and a scientific tool. Really outstanding!

All my best,

GT

543 (edited by Curt962 2020-04-20 06:27:28)

Re: Recommended reading for EQ

Hello GT!

Overall, a very nicely uniform Plot.    The 10db upslope at lower frequencies is bit more "Harman-esque" than I would prefer, but roughly coincides with the Research that suggests we listeners tend to dislike a Ruler Flat in-room response.    I wish there was a way for you to experiment with the RME "Dynamic Loudness" function.   That is a God Send!   

Anyway...it would be fun to maybe trim that upslope by a bit, .and listen.   I understand that personal preferences will always prevail, (say that fast.. 3x)  but 10db is a bunch.   Beyond that GT, I don't know what to add.   I'm more accustomed to dealing with Mountainous Peaks, and Bottomless Nulls...:)

*Update:  If you are routinely listening a low levels...this elevated low freq response may not be such a terrible thing.   Fletcher & Munson could comment further.  smile

Nonetheless, if you are indeed a Low Vol Listener,  it might be educational for all if you were to trim back the rise in the LF range to about +7db.    This would loosely emulate the RME Dynamic Loudness Feature (which works on a Volume dependent, sliding scale)

But IMUST find something to groan about!  smile  (Us old guys...never happy)

  Maybe you have some RT60 data to share.  A Waterfall Plot   No magic number there, just a nice, uniform decay is what I'm looking for. 

Beautiful Room!

Best,

Curt

Vintage 2018 ADI-2 DAC. "Classic Edition"
Cables:  Red Ones, and White Ones.
Speakers:  Yes (2)

544 (edited by KaiS 2020-04-21 00:09:07)

Re: Recommended reading for EQ

fisico wrote:

The room itself is a difficult environment, because it is very tall and as such there is still a relevant naked surface area, even if I have large absorbing and/or diffractive pieces of furniture, a fireplace, a slightly tilted wall, a recessed window and a vaulted ceiling, all contributing to deviations from the "nude rectangular box" nightmare. Approximate dimensions are 6.6 meters length, 4.5 meters width and 5.5 (at the top) meters height, 1m solid brick walls, built in 1765.

...

In order to get the best possible sound out of this room and that equipment, I first played a lot with careful placement of the speakers and the listening position. I spent a long time moving the speakers and the sofa around, ...

...Of course I am always ready and willing to experiment and learn whatever possible improvement any idea or piece of gear can bring to my listening pleasure, so if you have something to suggest me you are more than welcome.

What a nice place you have!


You seem to be satisfied, but if you're curious I could suggest a different approach:


The B&W speaker per se have an almost linear on axis frequency response and need no EQ correction..
All the bumps and dips you measure are caused by reflections from nearby surfaces.


But- measuring in the far field is missleading:

Our ears do not react the same way as a measurement mic in the far field, specially in the freq. range above about 200 Hz.

Our auditorial system can clearly separate direct and reflected sound.
Mainly the direct sound contributes to the received frequency response, the
later reflections just add a sense of room and mix with the recorded ambience in the music.
This effect get's stronger the longer you listen, the more your ears are "trained" to a certain ambience.
The room "disappears" the more time you spend listening.



Distracting are primary surface reflections, because they are closest and loudest rel. to direct signal.
Our brain has a hard time to separate them, they are the main reason for "smear".
EQ cannot change them.



Speaker placement has a huge influence on the primary reflections.
Here my receipt to optimize speaker placement to either reduce or integrate surface reflections:


1. Place the speakers much higher, about 1 extra meter at best, to reduce floor reflection and increase the time difference between direct and reflected.

This takes good advantage of you exceptional high room, where ceiling reflection is of minor interest due to it's long travel path.
This will reduce standing waves in the room too.

You maybe need to slightly angle the speakers downwards and inwards then to aim at the listening place.
You can still "shoot" a bit above the head, as higher positioned sound sources increase the upper midrange, caused by the HRTF.
Try what sounds best.

Place the carpet at the area where a mirror would make the speakers visible from the listening position.


2. Move the speakers back to the wall. This will integrate the low frequency reflections into the direct sound, as the sound travel path between direct and reflected becomes much shorter then 1/4 wavelength.

This mainly linearizes and, more important, time focuses the upper bass range. The result is a more defined and punchier bass.
Midrange and treble are usually uneffected, as the speakers directionality increases much with higher freq.
In recourding studios speakers often are flush mount into the wall - no more back wall reflections at all.
This isn't possible at your place, but my proposal comes close.


3. Stay a bit farther away from the sidewalls, and place absorbent material at the "mirror points".
You have this bookshelve on the right - great.
I can't see the left.
Plants are great diffusers/absorbers e.g., and can look quite nice.
Place them into the reflection path's.


4. The final touch would be some soft EQ for a tasteful tweeking of the overall balance.

Re: Recommended reading for EQ

Kai,

I'm usually happy just to get a User to set up in an Equilateral Triangle configuration.   Stereophonic Sound was based on this Concept from it's infancy in development. 

Tweeters at Ear Level...Equilateral Triangle...we have a good foundation. 

One thing at a time.  smile

Before I get into "Precendence Effect" (early reflections) with users, I like to get BASICS in order.    "WAF" quite often causes problems.   I'm surprised I still have Hair!!  I've pulled so much out over time...  big_smile

MY Wife doesn't do this.   Thank Goodness for her!

Curt

Vintage 2018 ADI-2 DAC. "Classic Edition"
Cables:  Red Ones, and White Ones.
Speakers:  Yes (2)

546 (edited by KaiS 2020-04-21 20:45:33)

Re: Recommended reading for EQ

Curt962 wrote:

I'm usually happy just to get a User to set up in an Equilateral Triangle configuration.   Stereophonic Sound was based on this Concept from it's infancy in development. 

Tweeters at Ear Level...Equilateral Triangle...we have a good foundation. 

One thing at a time.  smile

Before I get into "Precendence Effect" (early reflections) with users, I like to get BASICS in order.    "WAF" quite often causes problems.   ...

Fisco is obviously far beyond the basics, with a dedicated room for listening.
Speaker placement is the key if room acoustics treatment itself is limited.

Equilateral triangle isn't a religion, even lesser so the concept of "tweeters at ear level".
It's a starting point for the average, not more.
I'm not asking to place the speakers in the ceiling.


In a reveberant room, like here, a bit smaller stereo base can give a more focussed result, enlarged stereo spread is generated by the room contribution.
Same applies to higher speaker placement.


Short time 1st order reflections are the number one source of unwanted sound colorations.
As these are time domain disturbances they cannot be remedied in the frequency domain, by EQ.
Neither by even the most complex DSP.


Smooth frequency response at the listening position is a desirable goal.
But achieving it with EQ leaves out the very basics of acoustics.
EQ is the spice on a meal made from the best possible ingredients prepared the best possible way.



My origin is, besides beeing Audio Engineer with my own not so small recording studio, Audio Consultant for building professional recording studios.
"WAF" - Wife Acceptance Factor - isn't an issue there.
Neither is room acoustic treatment.
Still you have to work with existing room dimensions, not always a studio is build from the scratch.

547 (edited by fisico 2020-04-21 23:53:50)

Re: Recommended reading for EQ

Dear Curt962, dear KaiS,

thanks a lot for all your kind suggestions and the time you spent for me writing your very welcome comments.

About tonal balance and the frequency response, I agree with you: she slope does look a bit steep. On the other hand it is more or less in tune with the non-equalised slope of those speakers (which I trust) in that room. In other words, with my equalisation I am trying to compensate for peaks and dips but the overall slope of the sliders on my graphic eq is rather flat.

Today I had a listening session turning the volume higher than usual and I agree that bass is quite strong and I maybe better turn down by 1-2 db the frequencies between 25 and 80 Hz. I actually miss a 15" woofer, Those 'big boys' have a stronger bass presence at a lower relative volume than the twin 10" of my B&W.

Yes it's a pity I cannot use the ADI-2 dynamic loudness, but my set-up configuration must have an external pre-amp because of vinyl so I use the ADI-2 at fixed line level and I can' enjoy that feature. What I can do is prepare a couple of progressive "loudness" PEQ settings on the ADI-2 for medium-low level listening.

A real problem of the room is a long reverberation time, due to all those naked walls, but this is a different problem than equalisation.

About speaker placement I somehow planned the furniture placement in advance in order to minimise the primary reflections. This is the situation

https://i.imgur.com/JTWf2rI.jpg

Primary reflections in A and B are totally eliminated because there are 90 degree (absorbing, also) traps which dampen and send back the sound to the back wall (or is it the front wall?). The reflection in C is eliminated by opening by 15-20 degrees the wardrobe doors, which I do during dedicated listening. In D the books in the bookshelf are staggered, so their spines act as a diffuser and not a reflector.

About raising the speakers by 1 meter, well, ehm ehm.... They weight 100kg each and I would need to design some solid pedestal and hire 4 strong men to place the speakers on top. Then, playing with their positioning would become a deadly game.... To cope with reflections on the floor I maybe try some coffee table first.

What I can try easily, and I will do it, is to narrow the speakers and at the same time push them back more or less of the same amount, in order for the midrange/tweeters to remain on the same diagonal drawn in the picture to keep active the reflection traps in A and B. Not very much, B&W recommends to have a minimum distance of 50cm between any point of the cabinet and any wall.

No WAF problem here, my wife is very sweet, this is my home office/listening space and, on the other side, I never comment on the decoration in her rooms of the house...

Thanks again, boys, I'll keep you posted about developments,

GT

548 (edited by KaiS 2020-04-25 23:55:48)

Re: Recommended reading for EQ

fisico wrote:

A real problem of the room is a long reverberation time, due to all those naked walls, but this is a different problem than equalisation.
https://i.imgur.com/JTWf2rI.jpg

Primary reflections in A and B are totally eliminated because there are 90 degree (absorbing, also) traps which dampen and send back the sound to the back wall (or is it the front wall?). The reflection in C is eliminated by opening by 15-20 degrees the wardrobe doors, which I do during dedicated listening. In D the books in the bookshelf are staggered, so their spines act as a diffuser and not a reflector.

About raising the speakers by 1 meter, well, ehm ehm.... They weight 100kg each and I would need to design some solid pedestal and hire 4 strong men to place the speakers on top. Then, playing with their positioning would become a deadly game.... To cope with reflections on the floor I maybe try some coffee table first.

What I can try easily, and I will do it, is to narrow the speakers and at the same time push them back more or less of the same amount, in order for the midrange/tweeters to remain on the same diagonal drawn in the picture to keep active the reflection traps in A and B. Not very much, B&W recommends to have a minimum distance of 50cm between any point of the cabinet and any wall.

Reducing the reverb relative to the direct signal is exactly what my proposal is heading for.


Even the first order reflections add to the reverberation and are doing the most smear to  the direct signal.
So reducing their level and increasing the delay between direct and reflected helps getting a more transparent and less reverberant sound.


The floor reflections are the worst, as their travel path is almost the same as the direct.
A small table inbetween you and the speakers won't help much, works as minor diffusor at best, but does not reduce or redirect the reflection's energy.


So the most effective single measure is changing speaker hight.


I quite often use these types of stones as pedestals with "adjustable" hight, decorated with black or colored cloth.
They are available in lots of different sizes, big ones (I prefer the ca. 50x25x25cm), even loosely stapled, 6-8 in 3-4 crossed layers, make a solid founding and cost almost nothing:
https://www.baubay.de/kalksandstein-vol … 0x250.html

Place them on (big and strong) creeper dollies.
The whole construction incl. the speakers are held together with one or two lashing belts each.
Cloth covererd overall.

Can easy and securely moved around with the speakers on top.
Plus- the heavy stones, together with the rubber rolls, give a nice extra decoupling from the floor.

I wouldn't limit the possible speaker position range by factory recommendation - finally your ears are the judge what's best.



What you missed in your drawing is the reflection from the back wall.
According to your drawing I can calculate a deep notch at about 60Hz, and a 5dB boost at 90Hz.
These do, opposed to other room effects that only affect the distribution, change the amount of energy radiated by the speakers, because they "load" the drivers.

The backwave cannot be totally avoided unless the speakers are flush-mount in the back wall.
But their effect can be upshifted in frequency with closer position to the wall, and kind of "tuned" to counteract other room modes.
Use an RTA to visualize the result of changes in realtime.



BTW: no reflection can be totally eliminated over the whole frequency range.
Absorbtion is always limited to wavelength's shorter then the thickness of porous absorbing material.
Exception: membran absorbers can be tuned to a low frequency band.


The amount of reverb energy absorbed is always proportonal to the surface area covered by an absorber.


In your case a curtain -
• in 20cm deep folds,
• up to the stucco high (like at the window),
• thick soft cloth (e.g. Molton 300g/sqm),
• 20-30cm in front of all the remaining parts of the back wall (leaving out bookshelve and door),
- would help the most, and would probably be the least distracting, to reduce reverberation.
If it's moveable, made from say, 5 pieces, you could even "adjust" it's effect.

Of course, if there's a Michelangelo fresco this would not be desirable smile

Re: Recommended reading for EQ

Hi Fisico!   

Pardon my absence.  It seems Medical Equipment is a Hot Item these days, and I'm the dude that moves it from Point A to Point B.   Busy!

I like the Curtain Idea in the High Ceilings.  This concept is applied quite effectively in Venues around the World.   Perhaps one with some interior design expertise could implement such a scheme in a visually attractive fashion.  I'm not that person. smile

The closest thing to a Fresco at my House is a Coffee stain on the Carpet.   One of a Kind.  Signed by the Artist (my Wife) 

Good Listening!!

Curt

Vintage 2018 ADI-2 DAC. "Classic Edition"
Cables:  Red Ones, and White Ones.
Speakers:  Yes (2)