It sounds funny

Suppose you have grown tired of the 150 styles that came with your keyboard. You want to expand your options to the 10,000+ styles available on the Internet by using the Accompaniment Machine. You download and try out styles and find that some are strange and that the sound of others is not as good as the ones on your keyboard. Does this mean that AMac makes lower-quality sounds than the routines in your keyboard?

The answer is no — AMac can produce accompaniments as good as the built-in ones. But we need to understand some facts about styles and MIDI to see where problems come from and how they can be corrected.

It is important to note that AMac does not make the sounds. With regard to style voices, AMac simply passes numbers specified in the style to the synthesizer (keyboard, virtual instrument, MIDI driver,…). If the sound is bad, the reason is that the numbers in the style are not matched to the synthesizer. The pathway to a good sound for any style is to match the numbers.

First, a quick review of the voice numbers in a style. A Yamaha-format style may include up to eight MIDI channels for different accompaniment functions (percussion, chord, pad, phrase, …). A separate instrumental voice may be assigned to each channel. The style contains from one to three numbers in the range 0-127 to define the voice. AMac reads these numbers from the style and sends them to the synthesizer. The first is the GM (general MIDI) number, generally recognized by all synthesizers. It specifies one of 128 standard instruments [1]. For example, the number 0 tells the synthesizer to approximate a grand piano as best it can. The number 60 corresponds to a French horn. Modern digital synthesizers can produce more than 128 sounds. The extra sounds are specified by including the XG (extended general MIDI) numbers. The problem is that there is no standard for XG voices — each synthesizer has it’s own set of definitions. If you send XG numbers inappropriate to a synthesizer, the device either ignores them or does something strange.

A style may also contain numbers to modify the qualities of a particular voice (reverberation, attack, vibrato,…). Again, the response depends on the synthesizer. An expensive digital workstation may respond to all commands, a basic keyboard may respond to a subset, while a virtual instrument may respond to none.

With this background, we can understand the issue. The manufacturer of your keyboard has ensured that the built-in styles use only the voices and qualities available on the device. Therefore, the styles always sound good. On the other hand, there is no guarantee of compatibility with the external styles that you gather from the Internet. They may have been designed for a high-end Yamaha workstation or even a different keyboard brand. Therefore, some styles will sound bad, whether you play them through AMac or load them directly into the keyboard.

Fortunately, there are solutions — you can play practically any available style in AMac and make it sound terrific on your keyboard. At the first level, we supply extensive libraries of thousands of universal styles with the AMac package. These styles use only GM instruments and standard drum sets, so they generally sound good on any keyboard. You can use the on-board equalizer in AMac to fine-tune the channel balance.

On the second level, you can achieve a perfect match to your keyboard with the Style Voice Optimizer. With this program, you can set GM and XG parameters for each channel to match the keyboard’s available voices [2]. You can also experiment with different quality settings and adjust the relative volume levels. It’s even possible to change the entire style orchestration. Your changes are permanently recorded in the style file.

In summary, suppose you find a style that is perfectly suited to a song, but that sounds clunky on your keyboard. If you load it directly into the keyboard and use the internal accompaniment routines, it will never sound any better. In contrast, AMac combined with SVO offers a path to match the style exactly to the device.

In closing, I should mention that there is one problem that cannot be corrected with SVO. Occasionally, you may run into a style with jarring occurrences of bird tweets and police whistles. This was not an attempt by the composer to be whimsical. Rather, the style was designed to call a drum set that is not available on your keyboard. In the percussion channel, different notes call different percussion instruments. By ill fortune, the note in your drum set was not a conga drum but a bird whistle. A correction would involve editing individual style notes, a difficult process. The best solution is to toss the style — there are thousands of others [3].

Footnotes

[1] You can download a useful report that lists GM instruments and several other parameters: MIDI Programer’s Reference.

[2] The instruction manual for your keyboard usually documents the GM and XG numbers of the available voices.

[3] Note that the styles included in the AMac libraries use the standard GM drum set. No bird-tweet styles have been included.

[4] Find out more about KBD-Infinity: Home page.

[5] If you have comments or questions, please contact us at info@kbd-infinity.com.

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