Howto: AlsaModularSynth as a guitar effect-processor

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studio32

Howto: AlsaModularSynth as a guitar effect-processor

Post by studio32 »

**About:

This tutorial aims to describes how you can use AMS (AlsaModularSynth) as a effect processor for your electric guitar.

** Before:
- you should have installed and set up right jack by qjackctl
- you should be able to hear 'realtime' and clean guitarsound out of your speakers.
- I think you need a sort of preamp or mixer to get guitarsound. I do use just a simple Boss distortion pedal for it and that works :)
- you should have AMS installed.
- You have downloaded and unpacked some effect for AMS:
http://www.lapoc.de/spinoffs/ams-guitrack-RFC1.tar.gz


1) Start jack

Code: Select all

qjackctl
Image


2) Start AMS

Code: Select all

ams
3) load a ams effect patch

File > load patch > (I loaded: ams-guitrack_RC1_edited.ams)
Image
> It is possible to change the color of ams ;) <

4) Connect ams in qjackctl

*** BE CAREFULL: Always put your sound down when connecting. I had once a awful and very very load beep through my speakers when I first tried to connect something! Remember ears are important for musicians!***

- Click on "Connect" in qjackctl. You'll see "system" and "system" plus 'ams' and 'ams' . Left is hardware, right is software. You should see capture on the left, and playback on the right. playback_1 == left speaker and playback_2 == right speaker, capture_1 == mic port and capture_2 == nothing/built-in laptop mic.

- For expamle, you'd want to connect capture_1 to playback_1 and 2. Highlight capture_1 and highlight the "system" on the right panel. Drag your cursor from the former to the latter.

Connect things now like this:
Image



5) You should here a 'effected guitar sound' now :)


-------------------------------------------------------------------------------------

To make things a bit easier and faster for repeating sessions.


qjackctl patchbay

You can save the connections setup via 'Patchbay' in qjackctl, so you can load it easier the next time you want to use AMS.

Patchbay > new > 'Create patchbay definition as a snapshot of all actual client connections? >> ok* > save.
The next time you can load this setup in patchbay easily.

* It is recommended to choose no and make a patchbay manually like it is explained in the patchbay howto http://www.rncbc.org/drupal/node/76

Image

(! You can also use (the latest) patchage which has also lash support: http://wiki.drobilla.net/Patchage )

Enjoy! :)

feedback!?: did you find this tutorial useful or have comments on the content. I like to hear it! Further questions or problem solving could be better take place in the other forum parts....


Further readings and reference:
- AMS: http://alsamodular.sourceforge.net/
- http://www.lapoc.de/spinoff-amsguitrack.php : AMS-Guitrack: ein virtueller Gitarrenverstärker für Linux
- Ams related blog: http://www.alsamodular.blogspot.com/
- http://www.rncbc.org/drupal/node/76 (about qjackctl: patchbay and conections)
- More guitar processors: www.linux-sound.org >> Effects Processors
- Presentation about recording a cd in a linux studio on the lac2008 by Hartmut Noack, with special attention to ams: http://lac2008.khm.de/2008-02-29/2008-0 ... oncept.ogv
- LADSPA (Linux Audio Developers Simple Plugin): http://en.wikipedia.org/wiki/LADSPA
- CAPS (The CAPS Audio Plugin Suite): http://quitte.de/dsp/caps.html[/i][/b]
Last edited by studio32 on Fri Apr 18, 2008 12:51 pm, edited 2 times in total.
zettberlin
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Post by zettberlin »

Brief description of the FX-setup and how it works:

1.) The patch aims to emulate a "real" amp that is:

low vol on the guitar should provide a clean sound. Having the volume at 10 one should produce the most freaked out metal-distortion. This goal can not be reached completely with every hardware-setup (e.G. guitar, preamp, soundcard) but the principle is in the design: you need to set up you very own hardware carefully to get to the point it works best.

1.1.) Tipps for the hw-setup

Start AMS and load the patch, connect it with jack in/out and connect your guitar to the appropriate pcm-port.

Start meterbridge with two channels:

Code: Select all

 meterbridge -t vu x x 
and connect channel 0 with the pcm-port your guitar is wired to. Then connect ams-out with the second channel of meterbridge. Channel 0 (the left one) shows the unprocessed signal of your guitar, the other shows, what ams makes out of it.

Now make you guitar deliver the signal, you consider the loudest, you would like to use. (!!!AGAIN: LOWER THE VOLUME OF YOUR SPEAKERS FIRST!!!!). Set the input of your soundcard with alsamixer to about 90%.

The left instrument of meterbridge should show values between -10 and -1 dB (it is MINUS OK ;-) ). Set the PCM-OUT Module in AMS to make the right instrument sway between -5 and 0 dB, Especially the input shall NOT reach 0dB.

Adjust the PCM-In of AMS also and keep the output reasonable - the balance is quite delicate, some setups give lots of headaches but I made every guitar sound OK with AMS guitrack yet. Even with most crude preamps like a cheapo Behringer USB-codec connected to the guitar via a cinch-cable and an adapter. ;-)

2.) How the amp works

Tim Goetzes CAPS-Suite brings the core-modules of the amp, be sure to have the latest version:

http://quitte.de/dsp/caps.html

The CAPS-Amp alone does not deliver satisfactory procession. It reacts like a pre-amp and wired directly to the cabinet-emulation it sounds like a distortion pedal connected to the CD-in of a cheap stereo. To get the sound one would expect from a real guitar amp, it needs something like a master-channel. This is what the compressor right after the AMP-module is ment for: if gain, threshold and ratio is set right, the signal from the amp gets compressed like the one from a preamp delivered to a power-amp. Tone and sustain are greately enhanced. Loudness of clean and distorted signal varys by 2-4 dB - a signal one can record with fun ;-).

All depends on PCM-in gain and AMP gain. Loudness can be controlled by the gain of Cabinet III also. The sound itself is controlled by the volume-knob on your guitar if everything is perfect and can be adjusted further by AMP-gain. If AMP-gain is set to 10 and still your guitar is not screeching like hell and producing endless sustain, something is wrong with the settings for input and compressor. With my guitars I get the most extreme metal-shred at AMP-gain around 2.7 - I never raise it to 3. 1.6 gives okayish clean-sounds with vol-knob at 3-5 and good crunch at 10.

3.) FX and Cabinet

Warning: the FX can produce a lot of hiss: use it wisely. Metal-shred gets fatter with some Flanger/Chorus - the 2 are combined in the preset-controller (Menu/View/Parameter-View), Phaser and Plate are also in place connect more FX at will and share your patches ;-) .

Cabinet II emulates speakers - it is not soo much "typical" but allows great differences for very special sound I tend to use 4 (Fender Vibro 68) and 5 (Marshall Plexi) only.

Sebastian Tschöpel gave me the hint to deploy AMS' simple delay to get a slapback-effect. It also pans the signal extremely so you get a most powerful guitar-deluge with distorted sounds... It can be controlled with the delay-module (ID16) and the stereo mixer.

4.) Misc hints

The 10-band EQ should not have great impact on the level of the signal, use it at will to find out.

The presets tend to forget their names, Make sure, there is NO whitespace before the name in parameter-view.

The plate-module sometimes forget its settings and defaults to 0 then.

Drive has only but little effect.

If you want more "classical" sounds, ues AMP VTS with the tonestack by David Yeh. It also has quite realistic realworld-amp simulation. I am stunned by the JCM 800-emulation (model 3). The same greasy drone one gets from a JCM made out of wire and circuits ;-)

Connecting to MIDI-controllers

if you have a MIDI-controller like a pedalset at hand, you can connect this to every parameter in the AMS-patch you like:

To wire the parameters with MIDI-controllers first connect your
controller-device or software with ams using the MIDI-panel of qjackctl,
then open menu/view/control center.

As you turn a knob or move a slider its ID lights up in the left panel
of this window. You can now mark the ID and a Parameter-ID of your
liking, click "Bind" to connect them and don't forget to save the patch
before closing ;-) .

Have fun experimenting with the stuff and share your experiences - AMS-guitrack is far from being perfect but it works. Lets make it even better ;-)
nostrum fungitur
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