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Introducing Hang Loose Convolver from Accurate Sound

hege

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Another way to use HLC with Roon is to loopback the output of Roon into the input of HLC to convolve the audio and output to one's DAC. The connection is lossless as show in the attachment.

Is it also lossless between HLC->DAC? Documentation isn't entirely clear. It just says to choose the sample rate that is most common for your music. Does it automatically switch?
 
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mitchco

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Hi Mitch, how does your zeroi latency compare with just running Dirac Live or any other DSP program doing its own convolutions as a stand alone or vst. Maybe just compare DL 3 and Audessy for starters?

Dirac Live does switching pretty well, but that is because DL is not using FIR correction at low frequencies, but rather IIR. So there is no latency with IIR at low frequencies, but there is no time domain (i.e. excess phase) correction at low frequencies either. So low frequency room reflections below Schroeder are not corrected. The last time I tested DLP, there is no individual gain control for each filter. Also, DL is a "closed" system as you can't import or export measurements/filters with other systems.

Re: Audyssey. I can't say as based on my tests, Audyssey is not in the same class as the other DSP/DRC software products discussed here. There is a limitation with the number of FIR filter taps which limits its effectiveness below Schroeder, where we need it the most. There is little technical information on how it works, even the patent seems obfuscated. The last time I looked, Audyssey is also a "closed" system.
 
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mitchco

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Good to know.
Another question, IIRC, VST3 offers 64bit precision (64bit floats, I would assume), is the internal processing (which is most likely FFT/iFFT-based convolution) also 64bit floats?
Not that this would matter for music playback but sometimes it would be nice to have lowest possible artifacts for more academic purposes ;-)

Hi Klaus, currently the FFT calculations are 32 bit float. I have played around with 64 bit double precision, and difference is so small I did not bother with the implementation. As you say, does not matter for music playback, but I get what you are saying :)
 
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mitchco

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Hi Mitch. You’ve been teasing us with this for quite a while. Any target date? I’ve been delaying my purchase of Audiolense until it comes out. (And your convolver looks like a very interesting product, BTW.)

Hi Another Bob. too many projects and not enough hours is the cause of the delay. Sorry, no ETA as of yet. In the meantime, in case you have not seen them, here is one article and another on Audiolense.
 
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mitchco

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Is it also lossless between HLC->DAC? Documentation isn't entirely clear. It just says to choose the sample rate that is most common for your music. Does it automatically switch?

Yes, lossless between HLC->DAC at the same sample rate. In the case of the plugins, yes, the filters switch automatically based on host sample rate. In the case of the standalone version of HLC, it is a bit of a hit and miss depending on the host application and OS platform. For example, using Qobuz on the Mac, when the sample rate changes, so does BlackHole (used for loopback) and so does HLC standalone app. However, in the case of Roon, it does not. Working with the developer of BlackHole, we have determined it is a bug in Roon and opened a ticket.

With HLC in standalone mode on Windows, it is a bit of a mess due to the number of audio API's on the platform. I may implement ASIO loopback as that is pretty much the only way for the host to signal HLC standalone app that the sample rate as changed. I say "may" as one approach is to use either the resampler in the music player host or use the resampler in HLC and pick a sample rate. If using a transparent resampler, I doubt there is any audible difference versus using the native sample rate filter. At least to these ears :) Of course, in HLC plugin mode the filters automatically switch based on the hosts sample rate.
 

richard12511

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Hello fellow ASR enthusiasts,

Just over a year ago @dallasjustice was kind enough to announce my new DSP calibration service here on ASR. Since then, 125 individuals have used my service to calibrate their sound systems. Coming back to my audio roots after decades in the software industry was fun, and I learned a lot.

I also accumulated independent measurement data from different loudspeakers in different rooms from around the world. Interesting patterns began to emerge, not only from the measurement data, but from client preferences for corrected in-room frequency responses.

Data analysis of the acoustical measurements pointed to a mathematical formula for applying the optimum amount of digital room correction to achieve accurate sound. This is what made (and makes) my DSP calibration service unique.

If interested, I hope to publish the results of the anonymized data in the next edition of my DSP book. Meanwhile, look for an upcoming Master Class video on Digital Room Correction on my website homepage, which will teach you about the process.

The need for a Hang Loose type of convolver began when I was working as a recording/mixing engineer in the 80’s. The band, producer, and I would huddle in front of the mixing console and monitors while I manually switched in/out various “premastering” 2 channel eq before the mix heads off to the mastering lab. It was our final opportunity to determine which eq gave us the best sound quality. It would have been great to have had something that was automated.

Then, 10 years ago, while creating digital room correction filters as a hobbyist, I wanted a convolver that allowed easy level matching and real-time switching between filters so I could determine which one I liked best. I could not find one that would accomplish this however. Ten years later, my DSP calibration clients were asking, how do I tell which filter sounds better? How do I know if it sounds better with or without the filter? So, the impetus for developing Hang Loose Convolver (HLC) had finally begun.

The capability to level match digital correction filters to bypass level and switch seamlessly between filters in real-time has been designed into HLC. There is science behind the design, which can be read here: https://accuratesound.ca/products.html

Key Features:
• Designed for loudspeakers and headphones
• Seamless real-time switching between filters
• Autogain level matching with manual gain adjustment
• Import Acourate, Audiolense, Focus Fidelity, and REW filters
• Supports stereo 32-bit float wav FIR filters in a zip file
• Automatic filter switching based on host sample rate
• 6 Filterbanks x presets = dozens of FIR filters
• System-wide and app specific convolution capabilities
• Zero latency, uniform partition convolution engine
• Standalone application mode and VST3/AU plugin mode

HLC Operations Guide (PDF).

Tested (so far) with:
Roon on Mac and Windows operating in standalone mode with loopback.
JRiver on Mac and Windows using VST3 plugin.
Audirvana on Mac and Windows using AU and VST3 plugins
Qobuz on Mac and Windows using standalone mode with loopback.
HQPlayer on Mac and Windows using standalone with loopback.
System Wide Audio on Mac and Windows using standalone mode with loopback.
Popular DAW’s like Ableton and Reaper on Mac and Windows using AU and VST3 plugins.

Pic of HLC running in standalone mode on a Mac M1:

View attachment 131920

I am happy to answer any questions you may have.

Happy listening!

Kind regards,
Mitch

Wow! This looks awesome. I'll have to try it. Kinda lost motivation trying to get Audiolense to work with my AVR/HDMI. I need to get back at that(even if it means purchasing something).
 

extracampine

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Hi Mitch,

Can you do a short ELI5? I currently sometimes use REW to generate convolution filters and import them into Roon. I heard that this adjusts frequency response but not time domain. I read about Acourate and Audiolense amongst other things. I also read about companies where you send in your recording from a calibrated Mic and they sent you back filters. Does HLC better all of the above? What's the best way to use it with Roon?
 
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mitchco

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Hi @extracampine DSP/DRC comes in all sizes and flavours. At the top of the heap is FIR filtering which provides the highest resolution control over frequency response plus it allows for independent timing adjustments like time alignment of individual drivers and speakers plus excess phase correction. I hope to publish a Master Class on DSP/DRC on my website in the near future which will be a 45 to 60 min video presentation expanding on this topic area.

While there are several DSP/DRC programs that can perform FIR filtering, Acourate, Audiolense and Focus Fidelity in my tests are the top three. Aside from the great psychoacoustic algorithms these software programs use, every variable is user adjustable so you can fine tune your loudspeakers to your room in a way no other DSP can.

These DSP/DRC software programs allows one to measure and analyze the acoustics, then design, and generate the FIR filters. Once you have the filters then you need a "convolver" to host the FIR filters. Some music players have convolvers built in like JRiver and Roon, some music players will use convolver plugins, like Audirvana can host a VST3 convolver plugin on Windows and AU on Mac., There are separate convolvers, some offered by the same manufactures of the DSP/DRC already mentioned like Acourate and Audiolense.

In the case of HLC, I designed it to run on most platforms and can accommodate virtually any audio scenario that requires convolution. It has a number of unique features as described in the first post. How to use with Roon is described in the operations guide.

I hope that helps a bit. It is a large topic to cover not only theory wise but the practical application for loudspeakers in rooms.
 

Sal1950

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In the case of HLC, I designed it to run on most platforms and can accommodate virtually any audio scenario that requires convolution. It has a number of unique features as described in the first post. How to use with Roon is described in the operations guide.
Hey Mitch, Been meaning just to stick my head in here and wish you best of luck with HLC, looks like a awesome piece of software. DRC has come so far in the last decade, can't understand why so many have no interest, it makes a world of difference to even the best of systems.
Happy 4th July
Sal
 
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mitchco

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Hey Sal, thank you. Like you say, DRC has come a long ways. Unfortunately, there are still DRC products that frankly are not very good. These are typically the ones that offer little or no user controls to even adjust the amount of correction applied. This typically results in "over correction" and peoples comments are killed the dynamics or sounds lifeless or the bass has no tone. This puts people off of DRC. Conversely, the really good DRC products have so many user controls that if you don't know what you are doing can also result in a less than ideal correction and again puts people off.

Over the years, I have written several review articles on DRC products by providing "step by step" walkthrough guides and a book that goes through the gory details. These were done to ease the learning curve on to use the really good DRC products, but still takes time, practice and a lot of listening to figure what each user control does and how it affects the sound. It is worth it in the end as every room has low frequency problems where one typically has +20 dB peak to peak low frequency response variations. High quality DSP/DRC can not only smooth the bass, but also restore the clarity of the bass where folks are hearing this for the very first time. It is a mind blowing experience!
Happy 4th July Sal!
Cheers,
Mitch
 

Sal1950

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High quality DSP/DRC can not only smooth the bass, but also restore the clarity of the bass where folks are hearing this for the very first time. It is a mind blowing experience!
Absolutely!
As a multich guy I have high hopes that the current Atmos craze will finally bring music recording into the 21st Century. With many speakers placed all over the room and most always minimally 1 subwoofer, DRC becomes a necessity for a decent experience.
Futures so bright, I gotta wear shades. :p
 

Dichotome

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I’m planning a future implementation of AudioLense XO and want to use several sync’d stereo DAC’s. I had therefore concluded that I would get a Mac Mini so I could use the Aggregate Device function to route the channels. But then I started to read about Daphile and I’m wondering whether it would be a better option. As it is Linux based am I correct in thinking HLC would not be compatible with it?
 

Ron Texas

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I have found @mitchco to be a great source of advice and understandable explanations of how to get the most out of your audio system.

Note that I will be merchandising Hang Loose mens boxer shorts. These are lined with a proprietary material which will increase your listening pleasure and enhance your sex life. Just having a little fun here...
 

mhardy6647

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I have found @mitchco to be a great source of advice and understandable explanations of how to get the most out of your audio system.

Note that I will be merchandising Hang Loose mens boxer shorts. These are lined with a proprietary material which will increase your listening pleasure and enhance your sex life. Just having a little fun here...

The exact opposite of DTC's Bullpen underwear, I feel compelled to note. :rolleyes:

https://www.duluthtrading.com/mens-buck-naked-bullpen-boxer-briefs-32815.html
 

Eurasian

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I have found @mitchco to be a great source of advice and understandable explanations of how to get the most out of your audio system.

Note that I will be merchandising Hang Loose mens boxer shorts. These are lined with a proprietary material which will increase your listening pleasure and enhance your sex life. Just having a little fun here...
"Gizmo" Rosenberg would be proud!
 

Sal1950

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