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Article: What is Accurate Sound?

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9 minutes ago, ALLDIGITAL said:

Mithco, thank you for a very informative article. I currently use a INNUOS Zenith SE MKII music server running ROON Core. I tried room correction in the past unsuccessfully using an Anti-mode 2.0 system. I am now considering two different approaches to room correction:

1. Roon Convolution filters 

2. New amplifier with room correction in the amplifier. (Lyngdorf TDAI with Room Perfect)

Assuming you are familiar with Room Perfect software, would you please share your thoughts on this product.

What approach to room correction do you think would yield the best results. Thanks for you consideration of of questions. 

 

I’m a huge fan of separating DSP from hardware like an amp. It gives you greater flexibility. I use convolution filters in Roon all the time. The great thing is they can be enabled/disabled with the tap of a finger and you don’t have expensive hardware designed to use DSP. 
 

 


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6 hours ago, ALLDIGITAL said:

Mithco, thank you for a very informative article. I currently use a INNUOS Zenith SE MKII music server running ROON Core. I tried room correction in the past unsuccessfully using an Anti-mode 2.0 system. I am now considering two different approaches to room correction:

1. Roon Convolution filters 

2. New amplifier with room correction in the amplifier. (Lyngdorf TDAI with Room Perfect)

Assuming you are familiar with Room Perfect software, would you please share your thoughts on this product.

What approach to room correction do you think would yield the best results. Thanks for you consideration of of questions. 

 

I've had both types of systems - years ago a TACT unit (same basic concept as Lyngdorf all in one ) and software based room correction. I also used a "pro" unit with Lyngdorf RC software licensed and built in.

 

Lyngdorf - one box. Simple. Few cables. And looks good. Once you run your initial measurements and setup, you are good to go. Works like an audio appliance. Just turn it on and play music. Disadvantage: you are stuck with their software DRC and HW. There are some workarounds, but they sort of defeat the purpose of the all in one unit. The DRC is  good.

 

Roon: flexible. You can use different RC software. Several of the leading RC softwares improve over time and you can easily update or change vendor. Make your measurement and correction file and Roon does the work. You can change electronics anytime you want and it doesn't matter. Roon also gives you the ability to use software for more than one system. In my house I have two different systems that I've measured with Audiolense, and each has it's own correction file.  I can pick either system and it's correction at the click of a button. Or I can run both of them at once. Roon handles applying the correct correction to each setup with no issues.

Audiolense RC works very well.

 

Today I'd definitely do it through Roon, unless I had compelling reasons to go with a one box solution like Lyngdorf.

 

 


Main listening (small home office):

Main setup: Surge protector +_iFi  AC iPurifiers >Isol-8 Mini sub Axis Power Conditioning+Isolation>QuietPC Low Noise Server>Roon (Audiolense DRC)>RPi4 (dietpi)>Kii Control>Kii Three >GIK Room Treatments.

Secondary Listening: Server>Matrix Element i Streamer/DAC (XLR)>Schiit Freya>Kii Three .

Bedroom: SBTouch to Cambridge Soundworks Desktop Setup. Living Room/Kitchen: RPi 3B+ running RoPieee to a pair of Morel Hogtalare. 

All absolute statements about audio are false :)

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13 hours ago, mitchco said:

Hi @R1200CL

 

Here is my review of Thierry's Room Shaper SW. Note Thierry's RS is based on events detection and modifications of only some portions of the input signal. It requires a VST plugin to operate.

 

Re: Audiolense XO - this version has the time domain correction capabilities which I recommend.

 

I use commercial DSP software like Acourate, Audiolense, and Dirac designed for loudspeaker and room correction.

 

Kind regards,

Mitch


I’m trying to understand if your service includes the use of DSP produced by Rom Shaper, or if one “must” add this in addition to files received back from you.
 

I think I understand your very nice review of Rom Shaper, that Room Shaper is something that’s added to Audiolence/Acourate DSP result.
 

I’m asking all this, cause both your and HAF services produce an outcome, that’s is very easy to apply to Roon or HQPlayer. No extra computer needed. Present, not so with Room Shaper. (And Dirac). 
 

Not sure if you’re the right person to ask, but if your answer is that end user have to purchase Room Shaper in addition, why is it not possible to mix to DSP processes in one one process, (zip-file). After all it’s only bits 😀

 

Another way of looking at DSP in general, is that it seems all these top 3 products, can be further developed in order to achieve what Room Shaper does.

I assume nothing forces us (the developer) to use technology like VST plugin to achieve this.

 

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7 hours ago, ALLDIGITAL said:

2. New amplifier with room correction in the amplifier. (Lyngdorf TDAI with Room Perfect)


Never purchase any hardware that includes DSP. It will be outdated within 12 to 24 months.

Look what happened to super expensive surround processor like Lexicon, Theta Casablanca, and others.

As far as I know, none of these products offer SW upgrade. 


I take this further, and say the same apply to a DAC.

 

It’s my understanding from the article or links (which include evaluation of Lyngdorf DSP), that several DSP SW doesn’t do what they’re supposed to do, or do it poorly. Some even makes tings worse. 
 

Peter Lyngdorf said:

“We spend between 8 and 9 million dollars to optimize the technology of RoomPerfect. One of the things we developed is a completely new measurement technology that has never been used before. For instance, we are complete immuun to noise in the measurements. 

 

RomPerfect may be a very good product, but you may check how good is his track of upgrad is on discontinued products. Since he is in control of both HW and SW, maybe it’s a good way to go. 

 

Maybe his partner Bruno Putzeys is using RoomPerfect technology in Kii ?

 

Maybe if you email Sean that did the evaluation, he will point you in some direction 😀

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2 hours ago, R1200CL said:

Maybe his partner Bruno Putzeys is using RoomPerfect technology in Kii ?

 

Kii doesn't have anything like RoomPerfect, and doesn't use room measurements. It's a different concept, NOT room correcton. 

Bruno worked/works for several companies on different aspects of products.   Doesn't mean what he does with one company necessarily has anything to do with what he does with another. 

 

That article you referenced isn't very current. I wouldn't put much stock in anything it says about a specific RC product, as they have all undergone multiple changes since then. I would find the more general conclusions useful: that RC can result in subjectively and objectively better sound if done well, and that listeners don't prefer an actual flat in room response - they perceive a gradual rolloff as flat. 


Main listening (small home office):

Main setup: Surge protector +_iFi  AC iPurifiers >Isol-8 Mini sub Axis Power Conditioning+Isolation>QuietPC Low Noise Server>Roon (Audiolense DRC)>RPi4 (dietpi)>Kii Control>Kii Three >GIK Room Treatments.

Secondary Listening: Server>Matrix Element i Streamer/DAC (XLR)>Schiit Freya>Kii Three .

Bedroom: SBTouch to Cambridge Soundworks Desktop Setup. Living Room/Kitchen: RPi 3B+ running RoPieee to a pair of Morel Hogtalare. 

All absolute statements about audio are false :)

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26 minutes ago, firedog said:

I wouldn't put much stock in anything it says about a specific RC product, as they have all undergone multiple changes since then.


And that’s why never purchase HW that can’t or will not support SW upgrades 😀

(And that probably also includes DAC’s, depending what you expect your DAC to do). 
 

Principle is that any sort of DSP should be kept away from audio manufacturers.

 

Probably going a bit OT now....

 

 

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Yes, this is again an truely excellent informative and educational post by mitchco, similar to the one he did on Dirac in February already touching many of the topics mentioned here.
After heaving read his February post I actually went the Dirac route for my Kii Threes to further explore the RC topic, which I had started before with just some direct filter corrections in the Kiis for the lower frequencies by using REW and a mic.
But what you can't influence there is any aspects of time alignment which however also can be addressed with Dirac. I finally decided for a miniDSP SHD with Dirac installed and am very pleased with the result. What is still open for me is to experiment with different (industry) target curves mitchco also mentions in his posts. Dirac might not be the ultimate solution, but for me it seemed a good solution to start with, especially being integrated into the miniDSP hardware.
But I most likely wouldn't have gone this "enhanced RC" route (and taken the extra but for me comparatively tolerable investment) if Mitchco wouldn't write or have written these kinds of posts here.
Mitchco, thanks very much for these!!

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On 7/14/2020 at 3:57 AM, Bob Stern said:

Mitch, do you know what smoothing is used in the frequency response graphs?  I don’t see that stated in the Audiolense user guide.  Is it a proprietary psycho-acoustic smoothing?

 

Hi @Bob Stern, it is proprietary psychoacoustic smoothing.

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7 hours ago, R1200CL said:


I’m trying to understand if your service includes the use of DSP produced by Rom Shaper, or if one “must” add this in addition to files received back from you.
 

I think I understand your very nice review of Rom Shaper, that Room Shaper is something that’s added to Audiolence/Acourate DSP result.
 

I’m asking all this, cause both your and HAF services produce an outcome, that’s is very easy to apply to Roon or HQPlayer. No extra computer needed. Present, not so with Room Shaper. (And Dirac). 
 

Not sure if you’re the right person to ask, but if your answer is that end user have to purchase Room Shaper in addition, why is it not possible to mix to DSP processes in one one process, (zip-file). After all it’s only bits 😀

 

Another way of looking at DSP in general, is that it seems all these top 3 products, can be further developed in order to achieve what Room Shaper does.

I assume nothing forces us (the developer) to use technology like VST plugin to achieve this.

 

 

Hi @R1200CL room correction and Room Shaper are two different technologies solving two different types of room acoustic problems. Room correction, in the context of this article, corrects both the frequency and time domain. Room Shaper reduces the low frequency "decay time" in a room.

 

Room correction filters, in the context of this article, are static FIR filters that are convolved with the music in real time. Hence requiring a convolver to work. Room Shaper is not a static filter and processes the incoming signal based on a threshold level and strength that the user sets.

 

If you require further information, and why RS requires a VST, I suggest you reach out to Thierry directly.

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I think I just have to accept the fact that I’m into a mission impossible here 😀

And above my technical knowledge and understanding. 

 

Rom Shaper and what it does, can’t be converted to a convolver, which is the only “language“ in use for DSP, Roon accepts. 
 


As also Mitch wrote in his Room Sharper rewiew:

Room Shaper’s algorithm is different than DRC as it targets low frequency decay times that are longer than others. By using time domain correction, shortening the long decay frequencies to be the same as adjacent frequencies results in an even decay time over frequency in the low end. Much like changing the shape of ones room to a preferred room ratio. Room Shaper also assists in taking out the “boxy” sound of a room up to 600 Hz. What does “boxy” sound like? You will be able to hear it on the recording I made later in the review.

 

It should be noted that Room Shaper does not produce a digital FIR filter like DRC products where filtering is a linear transformation applied continuously to the whole signal. Room Shaper is based on events detection and modifications of only some portions of the input signal.

 

Room Shaper can complement any DRC product as it is targeting a different issue (i.e. reducing low frequency decay time) than DRC addresses (i.e. frequency and time domain correction)

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7 minutes ago, R1200CL said:

 

I think I just have to accept the fact that I’m into a mission impossible here 😀

And above my technical knowledge and understanding

 

Many people in this hobby get frustrated or shy away from this because of its complexity. I did for many years. Once I talked to Mitch about it and found out I could hand the hard parts over to him, all was right in my HiFi world. 
 

Everyone has their specialties. Computer audio and networking are right up my alley. Turntables and room correction are rocket science to me. I need to call in the experts or spend a ton of time educating myself and going through more trial and error than I care for. Mitch isn’t the only expert in the field but his service is fantastic and his results are objectively stellar. 
 

 


Founder of Audiophile Style

Announcing Polestar | Quick Community Reviews and Ratings

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15 hours ago, mitchco said:

Another technical point I would like to bring out is that all h/w DSP solutions, whether they be Lyngdorf, miniDSP, Trinnov, DEQX or Audyssey that is used in so many AVR's, is that their filtering capabilities are very limited. How much "filtering" that can be done is based on the number of FIR filter taps available.

 

In these h/w devices the number of filters taps available is typically limited to 1024 taps or up to 4096 and at the extreme, 8192 taps. Whereas the filters that can be developed for Roon or other software convolvers use 65,536 taps. This is a huge difference and what separates the OK from SOTA. It is a huge gap in performance, especially at low frequencies.

Yes, totally didn't think of that when  wrote my response. One of my favorite features of Roon is that it shows you the "signal path" and you can see just what is happening to your signal; you can see in the signal path how many taps are being used at any given time, and how that changes depending on the source material and what changes you are asking for in DSP.


Main listening (small home office):

Main setup: Surge protector +_iFi  AC iPurifiers >Isol-8 Mini sub Axis Power Conditioning+Isolation>QuietPC Low Noise Server>Roon (Audiolense DRC)>RPi4 (dietpi)>Kii Control>Kii Three >GIK Room Treatments.

Secondary Listening: Server>Matrix Element i Streamer/DAC (XLR)>Schiit Freya>Kii Three .

Bedroom: SBTouch to Cambridge Soundworks Desktop Setup. Living Room/Kitchen: RPi 3B+ running RoPieee to a pair of Morel Hogtalare. 

All absolute statements about audio are false :)

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Thank you, @Mitchco for a truly outstanding article. I will reread this and start absorbing the references over the next week or so. I have a step learning curve ahead of me!


 

QNAP > MACMini 2015 > Audirvana+ > M2Tech Young DAC > Magnum MP250 Class A pre > Wonfor designed Single Ended Class A Monos > modified Triangle Antal ESW (Tellurium Q Black).

 

 

 

 

 

 

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Unfortunately, such  design of the acoustic system can not be sufficiently phase-linear and can not meet the CBT (Constant Beamwidh Transducer) criterion


Moscow.Russia

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On 7/16/2020 at 4:06 AM, AudioDoctor said:

I have two friends that are actual rocket scientists if you ever need help setting up that turntable

 

I suppose that is fitting if the turntable is....out of this world !

 


Sound Minds Mind Sound

 

 

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10 hours ago, Nickolay_V said:

Unfortunately, such  design of the acoustic system can not be sufficiently phase-linear and can not meet the CBT (Constant Beamwidh Transducer) criterion


Can you enlighten us a bit more please. I did several search and to me it seems more the opposite .

Several links can be found here: http://www.audioartistry.com/index.htm

More about CBT and here

It is also my understanding CBT more applies above frequencies 3 to 400 Hz, where RC is more effective in the lower range. 
 

Somehow it seems engineers with sonar background is good FIR designers 😀

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On 7/15/2020 at 4:10 AM, The Computer Audiophile said:

I’m a huge fan of separating DSP from hardware like an amp. It gives you greater flexibility. I use convolution filters in Roon all the time. The great thing is they can be enabled/disabled with the tap of a finger and you don’t have expensive hardware designed to use DSP. 
 

 

 

I agree with you in the case of a 2.0 setup but if one - like me - wants to perfectly integrate monitor speakers with one or two subwoofers the Lyngdorf approach is hard to beat. Besides its powerful DRC/DSP (Roomperfect) it excels in integrating subwoofers with its build in (all digital) cross-over functionality that has simply all the flexibility that one could wish for. I for example like to not use monitor speakers full range and have a steep XO filter around 60 Hz. To let monitor speakers and subwoofers do what they do best. This approach also distresses the amplifier.

 

It is a challenge though to achieve optimal results. This is because Roomperfect itself is not able to determine the latency / distance / timing compensation needs for subwoofers. Lyngdorf recommends a rough distance measuring method but to achieve the best results, REW measurements are necessary. Fortunately there is a lot of material available online on how to do this.

 

Another advantage of hardware based DSP is that room correction works for all sources, so not only Roon.

 

A remark for @ALLDIGITAL. Lyngdorf is not the only player in the field. These other parties come to mind: Trinnov, Illusonic, DSPeaker and of course miniDSP/Dirac for smaller wallets.


Roon server (Mac Mini/i7/SSD/16GB/Uptone DC mod/external SDD via firewire/Uptone Audio JS-2 LPS) Streamer dCS Network Bridge DAC Chord DAVE Amplifier / DRC Lyngdorf TDAI-3400 Speakers Lindemann BL-10 | JL audio E-sub e110 Cables CAT6 UTP ethernet, Transparent premium AES/EBU, Nordost Leif Red Dawn analog RCA, Kimber 8TC speaker cables, custom star-quad power cables with Oyaide termination Head-fi and reference Bakoon HPA-21 | Audeze LCD-3 (f) | Audio-technica ATH-M50 Software High Sierra | Roon | Tidal | Qobuz Power and isolation Dedicated power line | Xentek extreme isolation transformer (1KVA, 0.0001pf, balanced) | Vibex one 6R power distributor | Uptone EtherREGEN | Emo Systems EN-70HD network isolator | Jensen CI-1RR isolator

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1 minute ago, skatbelt said:

 

I agree with you in the case of a 2.0 setup but if one - like me - wants to perfectly integrate monitor speakers with one or two subwoofers the Lyngdorf approach is hard to beat. Besides it's powerful DRC/DSP (Roomperfect) it excels in integrating subwoofers with a build in (all digital) cross-over functionality that has simply all the flexibility that one could wish for. I for example like to not use monitor speakers full range and have steep XO filter around 60 Hz. To let monitor speakers and subwoofers do what they do best. This approach also distresses the amplifier.

 

It is a challenge though to achieve optimal results. This is because Roomperfect itself is not able to determine the latency / distance / timing compensation needs for subwoofers. Lyngdorf recommends a rough distance measuring method but to achieve the best results, REW measurements are necessary. Fortunately there is a lot of material available online on how to do this.

 

Another advantage of hardware based DSP is that room correction works for all sources, so not only Roon.

 

A remark for @ALLDIGITAL. Lyngdorf is not the only player in the field. These other parties come to mind: Trinnov, Illusonic, DSPeaker and of course miniDSP/Dirac for smaller wallets.

I certainly here you when it comes to using sources other than Roon or JRiver. The Auralic Sirius is supposed to support convolution filters but I’m waiting to get my hands on it. 
 

With respect to using subwoofers, I believe @mitchco uses them and the digital crossover and has achieved nearly perfect results. It’s all available in Audiolense. 


Founder of Audiophile Style

Announcing Polestar | Quick Community Reviews and Ratings

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9 hours ago, The Computer Audiophile said:

With respect to using subwoofers, I believe @mitchco uses them and the digital crossover and has achieved nearly perfect results. It’s all available in Audiolense. 

 

To do this with monitors not playing full range you need XO-controlled separate outputs. Curious on how @mitchco achieves this.


Roon server (Mac Mini/i7/SSD/16GB/Uptone DC mod/external SDD via firewire/Uptone Audio JS-2 LPS) Streamer dCS Network Bridge DAC Chord DAVE Amplifier / DRC Lyngdorf TDAI-3400 Speakers Lindemann BL-10 | JL audio E-sub e110 Cables CAT6 UTP ethernet, Transparent premium AES/EBU, Nordost Leif Red Dawn analog RCA, Kimber 8TC speaker cables, custom star-quad power cables with Oyaide termination Head-fi and reference Bakoon HPA-21 | Audeze LCD-3 (f) | Audio-technica ATH-M50 Software High Sierra | Roon | Tidal | Qobuz Power and isolation Dedicated power line | Xentek extreme isolation transformer (1KVA, 0.0001pf, balanced) | Vibex one 6R power distributor | Uptone EtherREGEN | Emo Systems EN-70HD network isolator | Jensen CI-1RR isolator

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1 hour ago, skatbelt said:

 

To do this with monitors not playing full range you need XO-controlled separate outputs. Curious on how @mitchco achieves this.

 

Your Lygdorf has built in filters that removes signal under or over a crossover frequency you choose either on the digital or analog output. Lyndorf uses Butterworth and Linkwitz Riley. It is my understanding you need to apply these filters and XO before you do the room measurements, and then apply DSP. Agree ?
 

I suppose you could test out applying RC to Roon vs using the built in system. Or just use REW and measure how well RoomPerfect has been doing. 

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