hexter icon

hexter

Yamaha DX7 modeling DSSI plugin

News

2012/11/8: hexter 1.0.2 fixes a problem where exiting and restarting the GUI while editing a patch would cause the edited patch to become inaccessible (the editor would be disabled with an "edit buffer sync error" message.)

2012/11/2: hexter 1.0.1 fixes a linking failure on some platforms.

2012/11/1: hexter celebrates its eighth birthday with an integrated patch editor and a version 1.0.0 designation. Also included are more patch loading enhancements, NRPN parameter mapping, and the option to use floating-point math in the synthesis code instead of fixed-point.

2012/10/22: hexter development has moved to github. Download tarballs of release versions are still hosted here on SourceForge.

2011/5/24: Martin Tarenskeen has done wonders for hexter's ability to load different patch bank formats. His DXconvert tool handles even more formats, plus it can load patches from several other FM synths and convert them (approximately, at least) for use with hexter.

2011/1/26: Bálint Pfliegel has created a C# port of hexter named Sixport. I was surprised that a virtual-machine based implementation of hexter's rendering code performs as well as Sixport does—pretty cool! With the right combination of hardware and operating system, one can even run it in a browser, as part of the Pluto DAW. Some demos can be found here.

2009/1/4: hexter version 0.6.2 released! Release 0.6.2 is a maintenance release, which adds no significant synthesis features, but updates the code for more recent GTK+, adds better patch loading to tx_edit.c, and handles the new DSSI ‘sample-rate’ OSC method (by silently ignoring it.)

2007/4/11: hexter version 0.6.1 released! hexter now includes emulation of the DX7 LFO, plus amplitude and pitch modulation! Other new features include configurable performance parameters, better patch bank loading code, and a 0.5.x compatibility mode. (If you're already using the 0.6.0 release, you probably don't need to upgrade, but if you are distributing a 0.6.0 package, please do upgrade soon -- the installation paths in 0.6.0 were broken.)

2006/1/18: hexter version 0.5.9 released! New features include real-time control of the coarse frequency parameters, plus fixes for RPM, gcc 2.9x and 4.x, and Mac OS X 10.4 ‘Tiger’.

2004/12/29: hexter version 0.5.8 released! New features include a ‘volume’ control and MIDI CC volume handling, GTK+ 2.x or readline UIs, project directory handling, better error messages, and some new patches.

2004/11/16: Some recordings comparing hexter and a real TX7 are available here.

Introduction

hexter is a software synthesizer that models the sound generation of a Yamaha DX7 synthesizer. It can easily load most DX7 patch bank files, edit those patches via a built-in editor or MIDI sys-ex messages (ALSA systems only), and recreate the sound of the DX7 with greater accuracy than any previous open-source emulation (that the author is aware of....)

hexter operates as a plugin for the DSSI Soft Synth Interface. DSSI is a plugin API for software instruments (soft synths) with user interfaces, permitting them to be hosted in-process by audio applications. More information on DSSI can be found on the DSSI main page.

hexter is written and copyright © 2012 by Sean Bolton, and licensed under the GNU General Public License, version 2 or later. While this software is ‘free’ within the requirements of that license, I (Sean) would appreciate any or all of the following should you find hexter useful:

hexter benefited greatly from previous open-source efforts, most notably Juan Linietsky's rx-saturno, and FluidSynth by Peter Hanappe, et al. See the AUTHORS file in the hexter distribution for more details.

Requirements

hexter requires the following:

Download and Installation

Release versions of hexter may be downloaded from here.

hexter uses GNU autoconf and automake, and pkgconfig, so installation is only slightly more complicated than ‘./configure && make && make install’. See the README file for specifics.

The development version of hexter may be had by cloning the github repository:

git clone https://github.com/smbolton/hexter.git

Screenshots

The screenshot on the left shows the GUI main windows for three instances of hexter. Note that sys-ex editing is currently enabled in the channel 1 instance (details below). The middle screenshot shows the patch editor in ‘Widgy’ mode, while the one on the right shows the editor in ‘Retro’ mode.

Operation

To run the hexter plugin under the jack-dssi-host provided in the DSSI distribution, I do the following:

  1. Start JACK.

  2. Start jack-dssi-host, supplying the correct plugin path and filename (substitute <prefix> as appropriate):

    $ DSSI_PATH=<prefix>/lib/dssi sudo jack-dssi-host hexter.so

    jack-dssi-host should start, and moments later the hexter graphic user interface should appear.

  3. Use qjackctl or aconnect to connect jack-dssi-host to a MIDI source, such as vkeybd.

  4. Begin playing sounds! If you get no response, try clicking the ‘Send Test Note’ button in the hexter GUI. This sends a note directly via the host to the plugin, so if you hear sound now, look for a problem between the host and your MIDI source. If you still don't hear sound, I'd look for a problem between the host and your output device. If you continue having trouble, you might recompile with DSSP_DEBUG bit 2 set, which will cause the plugin to continuously output a quiet buzz to help debug your outgoing signal path.

hexter starts up with a default set of sound presets, or ‘patches’, that you can select either by selecting the GUI ‘Patches’ tab and clicking on the patch name, or by sending a MIDI program change from your MIDI source with the appropriate program number.

Patch Import/Export

hexter can import DX7 patch bank files in several formats:

You may use the "Import Patch Bank..." option in the File menu to import patches. After selecting the filename, you will need to specify the program number (0 to 127) at which to begin importing the patches.

Several patch bank files are installed with hexter in <prefix>/share/hexter/.

You may also export patch banks using the File menu "Export Patch Bank..." option. You can then select which of the formats to save in, and what range of patches to export. Finally, select the filename to which you want to save, and click ‘Ok’.

Synthesizer Configuration

On the ‘Configuration’ tab of the hexter GUI, there are a number of controls for configuring hexter:

Performance Parameters

The ‘Performance’ tab of the hexter GUI contains controls for the DX7/TX7 Performance Parameters:

Patch Editing

The current patch may be edited by selecting ‘Edit Patch...’ from the ‘Edit’ menu, which opens the patch editor window. All patch edits accumulate as a temporary ‘overlay’ replacing the current patch, but are not saved into the patch bank until you click the ‘Save Changes into Patch Bank’ button and complete the save process. (Once you've saved edits into the patch bank, remember to save the bank to disk using the ‘Export Patch Bank...’ option of the ‘File’ menu!)

Clicking the ‘Discard Changes’ button or selecting another patch from the ‘Patches’ tab will discard any active edits. At any time the top status line of the editor window will tell you which patch is being edited, and whether there are any changes in effect.

The editor has two modes of operation, selected by the ‘Editor Mode’ combo box near the bottom left of the editor window. One mode, called ‘Widgy’, uses standard GTK+ widgets for editing patch parameters, and displays graphical representations of envelopes and scaling curves to aid in comprehension of the patch parameters. The other mode, called ‘Retro’ is based on text-based editors of decades past. You may switch between editor modes at any time.

While the ‘Retro’ mode provides little in terms of visualization assistance, it can provide the experienced user with more efficient editing. Both the mouse and cursor keys may be used to select the parameter to be edited. Generally, the number keys are used to enter a parameter directly, the ‘-’ key decrements a parameter, the ‘+’ or ‘=’ keys increment the parameter, and the ‘delete’ or ‘backspace’ key will reset the parameter to a default value. Perhaps most convient for users without a separate MIDI keyboard, the space bar can be used to toggle a test note, even while changing patches with other keys!

MIDI Controller Mapping

In addition to the performance parameter MIDI messages mentioned above, hexter responds to MIDI volume (MIDI control change 39), sustain pedal (MIDI CC 64), and all-sounds-off, all-notes-off, and reset-controllers control messages (CCs 120, 123, and 121, respectively).

The operator parameters of the current patch can also be changed via the following MIDI control change (CC) and non-registered parameter (NRPN) messages. Messages marked with ‘*’ in the ‘Operator’ column will cause an immediate effect on playing notes, while the others will only affect subsequently-played notes.

CC or NRPN Operator Parameter
CC 16 (General Purpose #1 MSB) 1 * Frequency Coarse
CC 17 (General Purpose #2 MSB) 2 * Frequency Coarse
CC 18 (General Purpose #3 MSB) 3 * Frequency Coarse
CC 19 (General Purpose #4 MSB) 4 * Frequency Coarse
CC 80 (General Purpose #5) 5 * Frequency Coarse
CC 81 (General Purpose #6) 6 * Frequency Coarse
NRPN 0 6 Envelope Generator Rate 1
NRPN 1 6 Envelope Generator Rate 2
NRPN 2 6 Envelope Generator Rate 3
NRPN 3 6 Envelope Generator Rate 4
NRPN 4 6 Envelope Generator Level 1
NRPN 5 6 Envelope Generator Level 2
NRPN 6 6 Envelope Generator Level 3
NRPN 7 6 Envelope Generator Level 4
NRPN 8 6 Keyboard Level Scaling Break Point
NRPN 9 6 Keyboard Level Scaling Left Depth
NRPN 10 6 Keyboard Level Scaling Right Depth
NRPN 11 6 Keyboard Level Scaling Left Curve
NRPN 12 6 Keyboard Level Scaling Right Curve
NRPN 13 6 Keyboard Rate Scaling
NRPN 14 6 Amp Mod Sensitivity
NRPN 15 6 Keyboard Velocity Sensitivity
NRPN 16 6 Operator Output Level
NRPN 17 6 * Oscillator Mode
NRPN 18 6 * Oscillator Frequency Coarse
NRPN 19 6 * Oscillator Frequency Fine
NRPN 20 6 * Oscillator Detune
NRPN 21 5 Envelope Generator Rate 1
NRPN 22 5 Envelope Generator Rate 2
NRPN 23 5 Envelope Generator Rate 3
NRPN 24 5 Envelope Generator Rate 4
NRPN 25 5 Envelope Generator Level 1
NRPN 26 5 Envelope Generator Level 2
NRPN 27 5 Envelope Generator Level 3
NRPN 28 5 Envelope Generator Level 4
NRPN 29 5 Keyboard Level Scaling Break Point
NRPN 30 5 Keyboard Level Scaling Left Depth
NRPN 31 5 Keyboard Level Scaling Right Depth
NRPN 32 5 Keyboard Level Scaling Left Curve
NRPN 33 5 Keyboard Level Scaling Right Curve
NRPN 34 5 Keyboard Rate Scaling
NRPN 35 5 Amp Mod Sensitivity
NRPN 36 5 Keyboard Velocity Sensitivity
NRPN 37 5 Operator Output Level
NRPN 38 5 * Oscillator Mode
NRPN 39 5 * Oscillator Frequency Coarse
NRPN 40 5 * Oscillator Frequency Fine
NRPN 41 5 * Oscillator Detune
NRPN 42 4 Envelope Generator Rate 1
NRPN 43 4 Envelope Generator Rate 2
NRPN 44 4 Envelope Generator Rate 3
NRPN 45 4 Envelope Generator Rate 4
NRPN 46 4 Envelope Generator Level 1
NRPN 47 4 Envelope Generator Level 2
NRPN 48 4 Envelope Generator Level 3
NRPN 49 4 Envelope Generator Level 4
NRPN 50 4 Keyboard Level Scaling Break Point
NRPN 51 4 Keyboard Level Scaling Left Depth
NRPN 52 4 Keyboard Level Scaling Right Depth
NRPN 53 4 Keyboard Level Scaling Left Curve
NRPN 54 4 Keyboard Level Scaling Right Curve
NRPN 55 4 Keyboard Rate Scaling
NRPN 56 4 Amp Mod Sensitivity
NRPN 57 4 Keyboard Velocity Sensitivity
NRPN 58 4 Operator Output Level
NRPN 59 4 * Oscillator Mode
NRPN 60 4 * Oscillator Frequency Coarse
NRPN 61 4 * Oscillator Frequency Fine
NRPN 62 4 * Oscillator Detune
NRPN 63 3 Envelope Generator Rate 1
NRPN 64 3 Envelope Generator Rate 2
NRPN 65 3 Envelope Generator Rate 3
NRPN 66 3 Envelope Generator Rate 4
NRPN 67 3 Envelope Generator Level 1
NRPN 68 3 Envelope Generator Level 2
NRPN 69 3 Envelope Generator Level 3
NRPN 70 3 Envelope Generator Level 4
NRPN 71 3 Keyboard Level Scaling Break Point
NRPN 72 3 Keyboard Level Scaling Left Depth
NRPN 73 3 Keyboard Level Scaling Right Depth
NRPN 74 3 Keyboard Level Scaling Left Curve
NRPN 75 3 Keyboard Level Scaling Right Curve
NRPN 76 3 Keyboard Rate Scaling
NRPN 77 3 Amp Mod Sensitivity
NRPN 78 3 Keyboard Velocity Sensitivity
NRPN 79 3 Operator Output Level
NRPN 80 3 * Oscillator Mode
NRPN 81 3 * Oscillator Frequency Coarse
NRPN 82 3 * Oscillator Frequency Fine
NRPN 83 3 * Oscillator Detune
NRPN 84 2 Envelope Generator Rate 1
NRPN 85 2 Envelope Generator Rate 2
NRPN 86 2 Envelope Generator Rate 3
NRPN 87 2 Envelope Generator Rate 4
NRPN 88 2 Envelope Generator Level 1
NRPN 89 2 Envelope Generator Level 2
NRPN 90 2 Envelope Generator Level 3
NRPN 91 2 Envelope Generator Level 4
NRPN 92 2 Keyboard Level Scaling Break Point
NRPN 93 2 Keyboard Level Scaling Left Depth
NRPN 94 2 Keyboard Level Scaling Right Depth
NRPN 95 2 Keyboard Level Scaling Left Curve
NRPN 96 2 Keyboard Level Scaling Right Curve
NRPN 97 2 Keyboard Rate Scaling
NRPN 98 2 Amp Mod Sensitivity
NRPN 99 2 Keyboard Velocity Sensitivity
NRPN 100 2 Operator Output Level
NRPN 101 2 * Oscillator Mode
NRPN 102 2 * Oscillator Frequency Coarse
NRPN 103 2 * Oscillator Frequency Fine
NRPN 104 2 * Oscillator Detune
NRPN 105 1 Envelope Generator Rate 1
NRPN 106 1 Envelope Generator Rate 2
NRPN 107 1 Envelope Generator Rate 3
NRPN 108 1 Envelope Generator Rate 4
NRPN 109 1 Envelope Generator Level 1
NRPN 110 1 Envelope Generator Level 2
NRPN 111 1 Envelope Generator Level 3
NRPN 112 1 Envelope Generator Level 4
NRPN 113 1 Keyboard Level Scaling Break Point
NRPN 114 1 Keyboard Level Scaling Left Depth
NRPN 115 1 Keyboard Level Scaling Right Depth
NRPN 116 1 Keyboard Level Scaling Left Curve
NRPN 117 1 Keyboard Level Scaling Right Curve
NRPN 118 1 Keyboard Rate Scaling
NRPN 119 1 Amp Mod Sensitivity
NRPN 120 1 Keyboard Velocity Sensitivity
NRPN 121 1 Operator Output Level
NRPN 122 1 * Oscillator Mode
NRPN 123 1 * Oscillator Frequency Coarse
NRPN 124 1 * Oscillator Frequency Fine
NRPN 125 1 * Oscillator Detune

Fixed Point vs. Floating Point Rendering

hexter can be compiled to do its sound rendering using either fixed-point math or floating-point math. The difference in sound quality should not be audible, so the question of which type of math to use becomes which type of math is faster. On many older processors (e.g. PowerPC G4), the fixed-point math is substantially faster. With newer processors, the speed of each type of math depends on several factors, including the particular processor, the compiler and the compiler options used. It is often surprising which is faster for a given configuration!

On fairly normal posix systems (like Linux or OS X), you can compile a small test program, to test which type of math is the fastest on your processor. To do this, unpack the hexter tarball, cd into the ‘fptest’ directory, type ‘make’, then type ‘./fptest’. After 30-60 seconds, you should see a summary of the test results.

By default, hexter is built to use fixed-point rendering. If your test results say that floating-point is faster, then you can configure hexter to use floating-point with the ‘--enable-floating-point’ configure option.

Here are some test results from a few machines. Lower percentages indicate the faster mode.

Processor Fixed Point Floating Point
PowerPC G4 800MHz 49.5% 100.0%
PowerPC G4 1.07GHz 49.8% 100.0%
Pentium III (Coppermine) 933MHz 100.0% 95.2%
Intel Core Duo 1.83GHz, OS X 10.4.9 100.0% 92.9%
Intel Core 2 Duo 2.4GHz, Linux 3.2 100.0% 96.1% *
Intel Core 2 Duo 2.4GHz, OS X 10.4.11 100.0% 91.4% *
Intel Core 2 Duo 2.4GHz, OS X 10.6.8 61.5% 100.0% *
Intel Core 2 Duo 2.5GHz, OS X 10.6.7 62.0% 100.0%
Intel Core i7, OS X 10.7 52.0% 100.0%

* These three all come from the same machine!

Frequently Asked Questions

Q. The plugin seems to work fine, but the GUI never appears. Why?

A. Make sure the hostname of your machine is resolvable (if not, the OSC messages can't be sent between host and GUI). If your machine's hostname is ‘foo.bar.net’, make sure you either have an entry for ‘foo.bar.net’ in /etc/hosts, or that your DNS server can resolve it. Test this with e.g. ‘ping foo.bar.net’. To test that the GUI itself works, you can start it by itself (without a DSSI host) by giving it the ‘-test’ option, for example:

$ <prefix>/lib/dssi/hexter/hexter_gtk -test

Resources

The Wikipedia Yamaha DX7 page.

Steve Sims' site with lots of information, patches, and links.

Dave Benson's DX7 page, has much info as well as links to patch files.

The Synth Zone's collection of Yamaha links, which contains quite a few links to patch file collections.

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