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    The Computer Audiophile

    Introducing Hang Loose Convolver From Accurate Sound

     

     

    Many people in the Audiophile Style community are familiar with Mitch Barnett's fantastic articles about digital signal processing, room correction, loudspeakers and their measurements, and many other topics. Mitch is a multi-talented guy who started his company Accurate Sound to offer a calibration service. I used his services extensively when setting up my Wilson Audio Alexia Series 2 speakers in my new listening room (link). Now, Mitch has put his software development expertise to work to expand the offerings of Accurate sound, with a product called Hang Loose Convolver. 

     


    What is Hang Loose Convolver and why do you need it? 

     

    As this is just an introductory article, I'm not going to go all-in on DSP or even the full product at this time. That's a great topic for another article. 

    I look at Hang Loose Convolver as a software product that serves two different sets of people. The first I'll call music lovers and the second I'll call geeks. No calls or nasty emails please, these are just rough generalizations and I know full well that many people here are in both camps. Splitting the audience into two camps will help me explain why I think this product is game changing for almost everyone in HiFi. 

     


    The Music Lover

     

    I'm using the term music lover to describe people who don't know / care much about software, measurements, or how they are derived, and they just want to listen to music that sounds as good as possible. I have many friends who are in this camp. 

     

    Without turning this into a how-to or academic article, I'll briefly say that a convolution engine is a piece of software that processes convolution filters. Convolution filters are created for several reasons, among them room correction. Applications such as Roon and JRiver have built-in convolution engines to which a zip file of convolution filters can be added. Once the filters are enabled, the convolution engine processes the audio behind the scenes when the listen presses play. There's nothing to do but listen. 

     

    DSP and room correction have come a VERY LONG WAY over the years and now offer performance beyond what most audiophiles have ever heard. However, there are still holes in many convolution solutions offered by the main playback and library management applications. This is where Hang Loose Convolver takes us to another level. 

     

    I'll cut to the chase for music lovers. With Hang Loose Convolver, we can now use high end room correction while streaming audio from services such as Qobuz and Tidal, to DLNA renderers (endpoints). The last sentence needs a bit more explaining though. For years I've been searching for an application that supports streaming services, DLNA, convolution filters, and can use the convolution filters while sending audio over DLNA. There are a few terrible solutions out there that I wouldn't wish on my worst enemy. Now, using Audirvana or the new Audirvana Studio in combination with Hang Loose Convolver, it's finally possible to use room correction / convolution filters with DLNA audio endpoints and audio from both local and streaming services. THIS IS A BIG DEAL!

     

    Of course Hang Loose Convolver isn't limited to only DLNA. I just get excited about that because it's a first. HLC also works with any audio component that one's playback application can send audio to over USB, DLNA, or whatever other means one uses. 

     

    When I worked with Mitch to create my convolution filters for room correction, he sent me several different filters to listen to before I decided on my favorites. There is not a single best filter. Listening to different filters wasn't a completely seamless process because switching between them involved stoppages in playback. Hang Loose Convolver solves this issue because it can load up to six different filters and enable the listener to easily switch between them, all level matched, in real-time, without a hiccup. Just click the big buttons and the filter switches. Extremely simple.

    On the Hang Loose Convolver site there are images of it being used with Audirvana, Roon, JRiver, and HQPlayer to name a few. I've personally tested it with both Audirvana 3.5 and the new Audirvana Studio. 

     

    Again, there is so much more to cover that this introductory article glosses over. Much more to come at a later date. 

     


    Geeks

     

    I'm using the term geek to describe those who understand more about the whole convolution process, what's required, how it works, and the pitfalls pf previous products. Readers in this camp will certainly hop over to the Hang Loose Convolver website and understand most of what I'm about to say and obtain much more information. 

     

    • HLC's key features include:
    • Seamless real-time switching between filters
    • Autogain level matching  with manual gain adjustment
    • Import Acourate, Audiolense, Focus Fidelity, 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

     

     

    Wrap Up

     

    There's much more to come here at Audiophile Style about Hang Loose Convolver. I have a good feeling that tons of AS readers can benefit greatly from it. If you don't quite understand it or don't see how it can help you, I know @mitchco will be here to answer all your questions in the comments below. This brings me to another point, Mitch Barnett is one of the nicest, most helpful, and honest guys in the audio business. I recommend his services and now his application without a scintilla of hesitation. I say this both for end users and for audio companies. I think many audio companies could use Hang Loose Convolver in their products because it's extremely light weight and runs on nearly any platform in use today. I'm looking at you music server manufacturers who really should have convolution engines in their products :~)

     

     

    Product: Hang Loose Convolver
    Price: $129
    For more information see - https://accuratesound.ca/

     

     

     




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    1 hour ago, botrytis said:

    If your PC has Secure Boot and TPM 2.0 chip, otherwise you will have to get a NEW PC - period.

    Can’t you just purchase that chip ?

    I see it’s being sold everywhere. 

     

    Alao you may get around this by enabling secure boot in bios, which an app won’t discover is available. 


     

    image.jpeg.40f617ecf9fc3d6cc3ae5763b986f73e.jpeg
     

    https://www.windowscentral.com/tpm-windows-11-what-it-means

     

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    6 hours ago, R1200CL said:

    Can’t you just purchase that chip ?

    I see it’s being sold everywhere. 

     

    Alao you may get around this by enabling secure boot in bios, which an app won’t discover is available. 


     

    image.jpeg.40f617ecf9fc3d6cc3ae5763b986f73e.jpeg
     

    https://www.windowscentral.com/tpm-windows-11-what-it-means

     

     

    Actually, in reading no. It has to be built into the board and the BIOS. Those chips, like that, will only work with specific MB from that Manufacturer of the MB. Each MB would then have a different one and it has to be turned on in the BIOS.

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    @R1200CL, @bbosler, @botrytis Thanks for the input guys.

     

    For my particular case, there is good news and bad news.

     

    My PC is relatively new, less than two years old I think.  I double checked, and it does indeed have a TPM 2.0 chip.

     

    That's the end of the good news, as it is running Windows Home Edition.

     

    So I think I will need to look at my options here.  Upgrading to Windows Professional, just for what will be very occasional use of one piece of software, seems a bit drastic to me.  (and for what I do with a PC, over the years I have never found that I have had any other need or use for Windows Pro)

     

    I'll do some research on the VNC options, but I am also thinking that sometimes simple low tech is best.  As I said, this will only be an occasional use case, so maybe just running the PC keyboard to the listening position is good enough and less hassle.

     

    I'll have a think about this one!

     

    @mitchco - once HLC is fully set up and running with multiple convolutions installed, what is required to switch between convolutions?  Is it a simple one press of a key an the keyboard, or a click of the mouse somewhere? 

     

     

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    Well, Windows 10 professional lets you control more things in Windows, which is for tweakers, etc. 

     

    I had Win 7 Prof so I was able to install Win 10 Professional.

     

    The next big hurdle is - Secure Boot, which is basically an encrypted boot sector/OS Sector. It uses a specific HD format.

     

    Secure Boot Overview | Microsoft Docs

     

    One needs both the TPM 2.0 AND SECURE BOOT enabled in order to install Windows 11.

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    On 6/28/2021 at 12:36 AM, Confused said:

    @mitchco - once HLC is fully set up and running with multiple convolutions installed, what is required to switch between convolutions?  Is it a simple one press of a key an the keyboard, or a click of the mouse somewhere?

     

    Yes, mouse click on the big Filterbank buttons to switch filters. I could implement keyboard shortcuts, but I have not looked into it yet.

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    10 hours ago, mitchco said:

     

    Yes, mouse click on the big Filterbank buttons to switch filters. I could implement keyboard shortcuts, but I have not looked into it yet.

    Thanks for the clarification Mitch.

     

    I am thinking that there might be a few potential users like myself, that is using a PC (or Mac) as a music server and for the processing grunt, then relying on a network endpoint or similar for decent quality playback.  In other words, a few potential users for whom the PC or Mac is actually nowhere near the listening position.  Obviously there is little point having instant filter switching if you need to keep jumping up and down from the listening chair to select.

     

    So some kind of remote operation would be useful.  Obviously the options detailed by others would work, remote desktop, VCN or similar.  In my case I would be more than happy with keyboard shortcuts.  I could use my current keyboard with a USB cable extension, low tech but simple and robust.  (I like simple)  Plus I have a wireless keyboard somewhere that I could utilised. 

     

    Thinking about it, using the function keys would be cool.  They are already designated F1, F2 etc., ideal for Filter 1, Filter 2 and so on.

     

    But that is just me, and even without shortcuts I'd fine a way....

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    The spec sheet says HLC has zero latency.   Does that remain true if you are using it as a plug-in with JRiver?

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    On 7/8/2021 at 3:58 PM, Iansr said:

    The spec sheet says HLC has zero latency.   Does that remain true if you are using it as a plug-in with JRiver?

    Yes.

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    Mitch,

     

    Is there a trial period before purchasing. Fully functional as well. 

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    @RacerxnetSorry, not yet. It is on my todo list, but I don't have an ETA as I am currently working on other DSP projects.

    One can download and install HLC in bypass mode to ensure the entire signal path works for the intended scenario(s). If that works then one can purchase a license key and activate HLC. I offer a 14 day money back guarantee so if it is not to your liking, I will happily refund the entire amount.

     

    Kind regards,

    Mitch

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    @Mitchco: any news on the Linux version please?   Do you anticipate that HLC will be able to run on a Pi4?

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    @Iansr working on it, amongst other projects. Don't have an ETA. Will let you know when it comes available.

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    Thanks Mitch.  As you may have guessed my question above is related to the LMS question I posed on the AL forum which you kindly responded to.

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    5 hours ago, mitchco said:

    A couple of updates:

     

    1. HLC Linux version available for download. Please send me an email if you wish to target a different distro than Ubuntu.

     

    1. Most Digital Audio Workstations (DAW)’s support “automatic delay compensation” when using VST3 or AU plugins that have latency. The idea is that the plugin reports its latency to the DAW and the DAW compensates for the latency. So when tracking or producing audio for video postproduction, the tracks and/or video is delayed by the number of samples reported by the plugin so that the audio lines up perfectly with the video.

     

    While HLC is a 0ms latency convolver, some FIR filters have inherent delays, like if using linear phase FIR filters for example. The latency changes based on; type of FIR filter used, sample rate, number of filter taps, how much excess phase correction has been applied, and if using digital xo’s, whether min or linphase. HLC now reports the FIR filter latency to the host for automatic delay compensation:

     

    A 131,072 tap minimum phase FIR filter with minimum phase digital XO reports 0 latency samples:

    minphase FIR filter with minphase digital xo.png

     

    A 131,072 tap minimum phase FIR filter with linear phase digital XO reports 5,540 latency samples:

    minphase FIR filter with linphase digital xo.png

     

    A 131,072 tap linear phase filter with linear phase digital XO reports 37,863 latency samples:

    linphase FIR filter with linphase digital xo.png

     

    And if the sample rate changes and HLC does not find a matching FIR filter for that sample rate, then the FIR filter is resampled to maintain its frequency resolution and reports the new latency samples:

    full FIR linphase upsample.png

     

     

    Great for DAW’s, but what about consumer applications? Working with the folks at JRiver, the latest version of JRiver now supports automatic latency compensation. This allows one to use full tap length linear phase FIR filters with excess phase correction and not have any lipsync issues while watching movies.

     

    If folks can think of other consumer (or pro) applications that support the plugin model, please send me an email. I can work with the developer to implement automatic latency compensation.

     

    Happy listening!

     

    So cool!

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    2 minutes ago, mitchco said:

    Hang Loose Convolver (“HLC”) is now available on Raspberry Pi4.

     

    Requirements:

    Raspberry Pi4 4GB (2GB is likely to work).

    64 Bit OS Debian version 11 (bullseye).

     

    Performance:

    Process 32 channels of convolution using 65,536 tap length FIR filters at 48 kHz sample rate.

     

    Example playing a 7.1.4 Dolby Atmos (already decoded) music file using a VST3 plugin AudioFilePlayer. HLC is configured for 12 channels with 2 channel I/O being summed:

     

    HLC_RaspberryPi.thumb.png.711aebaa19311317caff6a90c4ae8480.png

     

    While this example is using a 7.1.4 (12 channel) file being played, the FIR filterset has digital XO’s and bass management built in. So, with 12 channels of direct signal and 11 channels of bass offloading means 23 channels of discrete convolution is being processed. With 23 channels of convolution processed there is still considerable CPU headroom and buffer size left.

     

    Note: HLC is a zero latency convolver, meaning no signal delay is added by the convolution engine. Therefore, one can process 65,536 tap minimum phase FIR filters immediately with no added signal delay. This is good for situations where lipsync is required but you still may want high-resolution FIR filtering capability of 65,536 tap length filters.

     

    HLC comes with HLConvolverHost, which allows you to plug in virtually any VST3 plugin for additional processing. The simple audio settings dialog allows you to easily choose inputs and outputs, sample rate, and buffer size so you can be up and running in minutes.

     

    Updated Operations Guide.

    This is fantastic!

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