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TX Audio (DAW)

Replacing the outboard audio rack gear with a Virtual Audio Rack and VST Plug-ins.

 

Doing this I had to make a few changes as to how the audio was going to be routed to the Flex SDR 3000. To remedy this problem I picked up a Focusrite Scarlett 2i2 USB interface. Scarlett 2i2 is a 2 in / 2 out USB recording interface featuring two award-winning Focusrite preamps. Housed in an attractive anodized aluminum unibody chassis. So far no RFI seems to be effecting the Scarlett interface.

2i2 

 

 

Purchasing the Scarlett you get a limited edition of Ableton 8/9 Lite Live software in either 32 or 64 bit versions.Ableton has been around for some time and has a nice clean layout for a DAW (Desktop Audio Workstation) application. The version in which Focusrite includes a serial number is limited to 2 in and 2 outputs but for amateur radio applications is fine especially at a free price..Since it is a live version of a DAW application you can use it to Host VST plug-ins in an actual live performance perfect for what we are doing. 

 

I went on line and look over several free high rated VST Plugins (Virtual Studio Technology). These VST Plug-ins can act as a virtual piece of audio hardware be it an effect, and instrument or perhaps a audio analyzer. For Essb/SSB and AM I built different chains using these virtual audio hardware pieces. 

 

The output from the Scarlett 2i2 is routed into Ableton Lite Live via an ASIO driver (I tried the ASIO4ALL driver) but the one included with the Focusrite seemed to perform better with less latency and cleaner audio, at least with my setup.

 

Input channel 1 of the Scarlett is attached to an older ATR30 Audio Technicia dynamic microphone, then routed virtually to Ableton Lite Live track 1 audio device 1 from there to audio device 2 a Gate/Limiter VST then from the post FX out to audio device 3 a Terry West Productions EQ from that post FX out to audio device 4 the Antress Modern Premeir and onto a Modern Series Exciter and Modern DeEsser VST and out master that being the line out puts of the Scarlett 2i2 interface.

 

Now to get that audio into the rig I used an ART DTI passive audio interface box which keeps the impedance in line as well of isolating the audio and keeping any RF off the signal. The output from the DTI is connected to the line level input of the Flex 3000 (this is the flexwire port on the back of the 3000) if the rig was a 5000 I would have used the balanced audio /XLR connector instead. This will bypass the front panel mic jack and its preamp which could insert more noise into the path. 

 

The current chain of VST plug-ins for AMfone is as follows the only difference between my two saved settings of these has to do with the audio TX bandwidth one is set for 50-4500 the other 50-3200 I saved separate profiles in both the Ableton Lite and in PSDR.

Focusrite preamp to input of Ableton then to the VST (Prefix) by Variety of Sound :

prefix

Next that is routed to MHorse P3 another VST by Terry West Productions

MHorse-P3 3

Next I connected to the Modern Premier to add a little Harmonics

MPMR

 And onto the Antress Modern Exciter

 MET4

and finally to the Antress Modern DeEsser

MDSR

 

The last Audio connection in Ableton is the Master which routes back to the 2i2 interface and as pointed out connects to the transceiver using the ART DTI between them.

 

The above VST routing is used on AM which seems to work well. When operating other phone modes there are other VSTs that are used and saved under a profile name which allows for simple on the fly changes. One very nice thing is there is a VAST amount of good VST plug-ins which are free making it easy to change your TX audio.

 

So roughly $150.00 for an interface like the 2i2 and which includes Ableton Lite Live and Focusrite VST plug-ings along with the many free VST plug ins that can be found and downloaded.. Versus $250.00 plus for just a DEQ2496 and add on any other hardware based rack components like perhaps a microphone pre-amp and needed phantom voltage for your condenser microphone(s) you may need (which is also covered with the 2i2 with GOOD Focusrite Pre-amps) ....

 

I can see why going the VST/Virtual route is gaining ground and fast. Oh and with less cabling and hardware needed you have less expouseres to RFI as well.

 

Using a Virtual Audio Chain instead of a hardware based deployment can be much more practical cost wise and you certianly have a vast assortment of hardware based VST options to choose from.

 

Information regarding many VST's and links to them can be found on the KVR Audio website: http://www.kvraudio.com/q.php

 

Rick 

 

N8SDR or do I now change the call to N8SDA "Software Defined Audio" ?

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