First Experiences with Ambiophonics

I recently came across Ambiophonics. Looking at the website I became curious. I don’t consider myself an audiophile (I don’t spend years optimizing details of my system), but I certainly enjoy listening to music, and I like to experiment. So Ambio really looked like something worth a try. At present, playing with Ambio requires a bit of an extra effort – compared to a stereo system that is already set up. So I decided to write down some of my experiences and compare some of the different options that are currently available. I hope that these observations will be useful for people who are ready to play with Ambio but who are not sure where to start.

A word of caution

I don’t have particularly good ears, and I am not a trained listener. I am not familiar with audiophile jargon, so I won’t try to describe my listening experience in great detail. Instead, I will focus on my practical experiences.

Physical Barrier

First of all, I tried Ambio with a physical barrier. I used a sheet of glass wool that I happened to have at home. The setup looked pretty much like Figure 1 in Glasgal and Miller (2006):

I did not play with this setup very long, but I remember that it sounded distinctly different from conventional stereo. It was much easier to locate individual instruments. And the instruments sounded considerably clearer. The nice thing about this approach is that you don’t need a computer, and you don’t need to optimize parameters. But the barrier is a bit impractical. So I decided to try some of the different software solutions.

Installing the Software

I decided to try four different solutions. Two of them( Noach – ATC and Ambiophonic DSP (www.filmaker.com/products.htm) ) are VST plugins that can be used with certain audioplayers. The Ambiophonic Audio Player is a java runtime application that can be downloaded from http://www.hotto.de/software‌/ambiophonicaudioplayer.html. Finally, the AudioMulch software ( http://www.audiomulch.com) can be used with the configuration file RACE.amh, based on the description at http://www.ambiophonics.org/PCMac.html).

Luckily I had already installed Winamp (http://www.winamp.com/) and Foobar2000 (http://www.foobar2000.org/), so I was reasonably familiar with these audioplayers that I used for ATC and AmbioDSP. I personally prefer Foobar, so I used the plug-ins with Foobar. I connect my laptop to my sound system via a USB-to-S/PDIF converter and a digital-to-analog converter and then feed the signal into my amp.

I downloaded the installation files for ATC and bought a copy of AmbioDSP. With AmbioDSP you need a bit of patience, because emails with passwords are not yet sent automatically. However, folks at electro-music are very friendly, and waiting for a couple of hours is really not a problem.

Since ATC was the first package that I managed to download, I started with that. The ATC documentation is very good, and I easily managed to install the plug-in. Running it with Foobar was straightforward. When I installed AmbioDSP a few hours later, I benefitted from this experience, since the process is essentially the same. The most important thing during the installation process is to select „George Yohng’s VST Wrapper“ in the DSP manager, which you can access via the „Preferences“ menu (press the „<=„ button).

The solution with AudioMulch is a bit different, since AudioMulch is more than just a plugin. I gave myself a few hours to play with the software (which is really quite intuitive), and then had no problem to open the Ambio file (RACE.amh) that is required. It would probably be possible to start with Ambio straight away (without investing time to get to know AudioMulch).

The Ambiophonic Audio Player (for simplicity I will refer to it as AmbioPlayer) is a more recent development, that only became available after I had played with the other three approaches. It is very easy to install (provided you have JAVA runtime environment installed on your computer; if not, you can easily get it from http://www.java.com‌‌/download‌/manual.jsp). This is probably the quickest solution if you want to try Ambio.

Noach ATC

Installing ATC was quite straightforward. The file „ATC pe1.0.dll“ has to be placed in the „components“ folder of Foobar. Then a button appears for the VST plug-in (in the image, this is the second button from the left, surrounded by the yellow circle):

You simply click this button, go to „Use VST Effect“, and then chose „ATC pe 1.0“. The following window will appear:

ATC is based on the RACE („Recursive Ambiophonic Crosstalk Eliminator”) algorithm. It has two main parameters: „speaker angle“ and „width“. It’s worth taking some time to optimize these two parameters for your loudspeaker setup. I used the file "speech_left_right_center_211.wav“ that can be downloaded from electro-music.com. It has three signals: one from the left, one from the right, and one from the center. I optimized the parameters for optimum stage width and ended up with values that were pretty close to the default values.

One nice feature of ATC is the switch that can be used to switch between Stereo and Ambio: when you chose “Ambio“, the window turns pink (instead of blue). So you always know which mode you are in. With the recording that I used (I don’t remember which one it was), there was a clear difference between Ambio and Stereo. The music became much more alive, and there was a feeling of “being there“. I also managed to hear details that I did not hear in stereo mode. The differences between two different pairs of speaker (one floor standing unit and one small unit for a bookshelf) were also more pronounced. So I fully agree with the ATC user manual, which says „The comparison of normal stereo to Ambio is an interesting one. To our experience it is simply devastating to normal stereo. Period.“

Later on I realized that Ambio is not always superior. One problem is that the effect is more pronounced in some recordings than in others. Obviously it doesn’t make much sense to evaluate Ambio on the basis of a solo recording where the soloist is located at the center. And it appears that good recordings benefit more from being reproduced in Ambio mode, whereas poor recordings don’t really come alive.

AmbioDSP

AmbioDSP was the next candidate. Under Foobar, the setup is similar to that of ATC. I simply had to place the file „AmbiophonicDSP v1.1.dll“ in the „components“ folder, and then select the appropriate plug-in from the VST button. If you start with AmbioDSP right away (without installing ATC before), remember to activate „George Yohng’s VST Wrapper“ in Foobar’s preferences menu.

AmbioDSP looks a bit more complicated than ATC in that it has 6 buttons to optimize parameters. However, the knobs on the right hand side („Balance“ and „Volume“) are not really related to Ambio but rather to the setup of your system. I found it helpful to have a „Balance“ knob since that helped me a bit to move the center signal to the location in the middle of the two speakers. Unfortunately, even that did not fully resolve the issue.

AmbioDSP is based on a slightly different version of the RACE algorithm, which is called “RACE G”. You now have four parameters to play with, and this gives you more control. „Delay“ and „Space“ are similar to the ATC parameters. On top of that, you can define the amount of recursion. This parameter turned out to be relatively uncritical – 30% sounded about right. On the other hand, the “Delay“ parameter is critical – only a relatively narrow range yielded good results. The “Space“ and “Zentrum“ (why not use an English name for this?) are a bit more difficult to optimize. AmbioDSP comes with a number of presets (Pop, electro/game, Jazz/acoustic, Classical/Movie, Wareing and Bypass). With my system, only the “Pop“ preset yielded good results, no matter what type of music I listened to. My final choice of parameters was reasonably close to the “Pop“ presets. I used a lot of “Space“ to widen the soundstage.

The „Zentrum“ knob is special in that it allows you to move center signals towards you or away from you. This allows you to make center signals more or less audible. However, I found this a bit unusual with the test signals: the center signal sounded weird when it was much louder (or much less loud) than the side signals.

My approach to setting up the system relied on my sound level measurements: I adjusted the parameters until the left, center and right signals were equally loud. This was also the combination that sounded best to my ears. And I really liked the sound: There was a considerable improvement over ATC in the sense that there was a clear winner whenever I switched from one plug-in to the other. The sense of “being there“ was even more pronounced with AmbioDSP.

AmbioPlayer

AmbioPlayer is the most recent addition to the Ambio family. It is available in different versions: As a player (which can be used with .wav files), and as a transcoder. The transcoder lets you specify an input device and an output device. For me it works great with “Virtual Audio Cable” (see below), because I can connect it to any Audioplayer. My description will focus on the four-channel version of transcoder, but the player is very similar.

You can chose if you want to use two channels or for channels. You define parameter values for “RACE attenuation” and “Delay”, as with ATC. In addition, there is a “Center” parameter which is similar to the “Zentrum” parameter of Ambio.DSP, with a less pronounced effect. You can easily “Bypass” the Ambio signal to compare it to stereo. My impression was that this does not work quite as well as with ATC, in that there appear to be slight volume differences between Ambio and stereo – but this may be an artefact that is more due to my hearing abilities than to the software. For four channels, it is nice that you can adjust volume and balance which essentially means that you can adjust each speaker individually. The transcoder works very nicely with my Terratec DMX 6 Fire USB sound card.

The transcoder is by far the simplest solution for a beginner. You just need a tiny JAVA applet. The layout is very clear, and you don’t spend much time configuring things. One limitation is that the increments for the “Delay” parameter are quite large (22.6 ms). The good thing about this is that you don’t lose much time finding a reasonable parameter combination. Compared to surround decoders, there is a slight limitation in that you can’t specify individual delays for each of the four speakers, which would be helpful if the speakers are not equidistant to your hearing position.

AudioMulch

The approach based on AudioMulch is quite different from the other two approaches. AudioMulch is a user-friendly software that can be used to generate and manipulate sounds. So it can do a lot more than just Ambio. To use it for Ambio, you need to install AudioMulch (http://www.audiomulch.com/download.htm). You also need to go to http://www.audiomulch.com/download.htm and save the file displayed in your browser as “Race.amh”. You then open “Race.amh” in AudioMulch, and the result will look like this:

To play a file, double click the “SoundIn” button and chose the appropriate options. This is not a music player like Foobar, so playing files or playlists is not quite as simple. The advantage is that AudioMulch gives you a lot of control over your output. For most users it will be sufficient to use the control buttons that are displayed in the image above. This is not quite as easy as with ATC, but the result is the same – at least I could not distinguish the sound (as far as I know, it’s the same algorithm). Which means that I prefer the sound generated via AmbioDSP. The biggest advantage of  AudioMulch is the additional flexibility. You could theoretically use any of the inbuilt effects to add filters and modify the sound according to your taste – and end up with a new version of the RACE algorithm. Most users will not have any desire to dig that deep..

TacT

The next step would probably to use the TacT Ambio processor, which can easily be integrated into your system without any need for a PC. I imagine that this is the most convenient solution, especially if you are interested in home cinema. I think the price of TacT’s Ambio processor is fair, but it was too high for me to buy a unit to simply play with it in order to compare it to the PC-based solutions. TacT’s Room Correction System might be very useful to ensure that both stereo channels reproduce identical signals, and this could help to move center signals to the correct location in the middle between the two speakers.

A word of caution

Initially I used an old tube amp. With this amp, the problem was that I did not manage to get the center signal to come straight from the center. I was quite surprised about that, so I took my old analog sound level meter to measure sound levels. In stereo mode all three channels were equally loud. Probably there are slight differences between the two channels at different frequencies. Later on; I got a solid state amp. With this amp, center signals really come from the center. So my suggestion is not tu use Ambio with tube amps. 

I have also tried Ambio on my Dell Latitude laptop. This laptop certainly does not have good speakers. Ambio sounded a bit better than stereo, but the effect was not dramatic. I also got an inexpensive pair of PC speakers (Logitech X-120), but this did not improve things much. If you want to give Ambio a fair try, you should use a decent system. If you cannot generate an s/pdif signal that you can feed into a DAC (or a CD player with a digital input), then you may be better off converting your favorite stereo recordings to Ambio.

My impression is that a simple sound level meter is helpful to make sure that both channels have the same sound level.

Using Virtual Audio Cable

Sometimes the existing solutions are less flexible than I would like them to be. For example, I like to listen to last.fm, but I had no idea how to direct the last.fm output to AudioMulch. Ross Bencina suggested to use “Virtual Audio Cable”, a little piece of software that can be downloaded from http://software.muzychenko.net/eng/vac.html. It costs 30 dollars, and it allows you to virtually connect different audio devides on your computer without having to use physical cables. For example, I can direct the last.fm signal to „virtual cable 1“, which is used as an input for AudioMulch (or the transducer version of the AmbioPlayer).

Converting Stereo to Ambio

If the situation arises that you want to listen to Ambio in a setup where you can’t use your PC, it might be helpful to be able to take “Ambio sound” with you in the form of sound files (.wav, mp3,…) that have been converted from Stereo to Ambio. It is not difficult to do this. Foobar can easily convert files, and AudioMulch allows you to save the output. Any of the approaches described above can be connected to a virtual audio cable that directs the output to a file recorder.

Comparison

Comparing the different approaches to Ambio was interesting because each approach has its advantages and disadvantages. The following table is an attempt to characterize the approaches that I have experimented with:

Both plug-ins (ATC and AmbioDSP) cost about $ 50, which seems fair to me. One nice thing about ATC is the unlimited trial. I also like that ATC turns pink when you switch to stereo – then you always know which mode you are in. ATC has an excellent manual, which means that you should really not have any problems getting it installed. If you are curious about Ambio, I suggest you first check out ATC – because of the helpful manual and its ease of use.

AmbioPlayer is probably the best choice if just want to play with Ambio without investing too much time – simply because it is so easy to install and to configure. For beginners, it is helpful that the “delay” parameter can only take a handful of values, so you can quickly pick a value that sounds good. However, the other solutions are better for fine tuning of the delay parameter.

I recommend AudioMulch if you really want to understand the details of Ambio (and are willing to get familiar with the software), or if you already own AudioMulch. AudioMulch is probably the best solution for those who like to experiment. Both AmbioPlayer and AudioMulch can be used for a setup with 4 speakers.

I have two personal favorites. One is AmbioDSP with Foobar. It is easy to use and it works well with audio players like Foobar. Since I use Foobar anyway, using AmbioDSP is straightforward. You can use features of audio players such as playlists, and you can listen to a large variety of file formats. From my personal point of view, the most important argument in favor of AmbioDSP is the sound quality. I like the fine tuning that becomes possible with a larger number of parameters. AmbioDSP certainly generated the widest sound stage for me. However, this may partly be a result of listening habits; the G version of the RACE algorithm that is used by AmbioDSP sounds more “stereo-like” than the F version used in RACE.amh.

My other personal favorite is AmbioPlayer – because it’s so simple to use. It is also nice if you want for channels of Ambio, and it interfaces nicely with my multichannel soundcard. I like the simple layout which has all of the important features.

If you don’t like high-tech (i.e. the use of a computer), you can still listen to Ambio: just get yourself a physical barrier and enjoy the sound! This is also an excellent first step if you want to experiment with Ambio, but do not like to install software.

Personal Conclusion: My Ideal Plug-in

I hope that one day Ambio will be available as an option in any decent music system. Before that can happen, the Ambio community will need to grow. Making the use of Ambio as simple as possible will help. Comparing the different approaches, I came up with a number of ideas:

·         All plug-ins should offer a trial version.

·         It should be possible to enjoy Ambio without spending much time on parameter optimization. Any user can easily measure the distance between the pair of speakers, and the distance to the speakers (measuring angles is considerably more difficult / inaccurate). The value of the delay and gain parameters (in RACE) should depend largely upon these two distances. So it should be possible to enter these two distances into the plugin, and then let the plug-in calculate a first guess of the two parameters. This first guess could be labeled „100%”, and the user could then do the fine tuning (say between 90% and 110% or between 0% and 200%).

·         My favorite plug-in would look similar to AmbioDSP, but the knobs for “Balance” and “Volume” would have a different color. The corresponding parameter values should be used for all presets (jazz, classics, pop etc). There would probably be no knob for “Recursion”, since a standard value (30% or so) could be entered along with the two distances (speaker to speaker, listener to speakers). The system would calculate starting values („100%”) for “Delay”, “Space” and “Center” (For consistency, I would get rid of the German term “Zentrum”).

·         It would be great if a test signal (left – center – right) could be integrated into the plug-in along with a few sample sound files (with a large sound stage) that help you fine tune parameters. Ideally, it would be possible to connect a sound meter and to optimize the value of the “Center” parameter until center signals generate the same sound level as left/right signals.

·         The manual would be similar to the ATC manual: with sufficient details to make sure everybody can set it up, but not as thick as a book!

·         There should be a simple switch to go from Ambio to Stereo, and the change should be easily visible (as in ATC).

Acknowledgements

I am grateful to the people who were involved in developing Ambio. Above all, I would like to thank Ralph Glasgal for his perseverance, for maintaining the Ambiophonic.org website, for providing RACE.amh and for his great patience answering the many questions that I asked him!