Stereo Tool

Okay let's say a commercial station replace their expensive Omnia or Optimod processor units, if you put this in the audio chain between the studio and the transmitter there would be a 1-2 second delay from the studio to the transmitter right?

The jocks or on-air personalities listening to an air feed would hear themselves from 1-2 seconds delayed.

Is there any way to get this to work in real-time or have a delay of less than 500 ms?

Dominick Pannone
Broadcast Engineer

hi Dominick,

Current public version of Stereo Tool (4.22) has delay about 1.5sec at max quality. in few days will come new much improved version, with much less delay, less cpu usage, better quality, better control over CPU usage/quality, new features .. etc..

In my case i use Audio over IP WiFi 5GHz band link from studio to transmitter and thru STL software i have there ~50ms latency. For current "Stereo Tool BETA" latency is about 15-75ms (depending what quality is used and soundcard settings).
I use max quality settings and Juli@ soundcard with ASIO so overall latency is about ~130ms. To be honest i never measure exact latency, but i'll do that when finall version is out.

Jocks in our studio are listening "monitor output" from mixer (not output from receiver/tuner) so they actually have no idea about latency.

btw afaik new Orban 8600FM will be in stores soon .. and what i heard, latency will be more then ~10ms which is in current 8500FM model.

HI Bojcha.
So what about delays in new versions?
i'm going to use 2 pc, 1st for playlist (RadioBoss) --- mixer --- 2nd for processing and streaming --- fm transmitter.
are there any requirements for pc? (my pc for processing: 3rd gen. core i7, 16gb memory, 1tb hdd 7200rpm (do i need ssd?), juli@ sound)
i'd like it work real-time. (fm transmitter is in the studio, coaxal cable will be 7-8 meter)
thanks.
(sorry for bad english, i'm from Tajikistan)

hi Navruz,

What you need is good Intel c2d or dual core cpu (minimum) dual channel memory. SSD is not so important except if you want faster boot time for PC.
So, your PC will easily do the job.

Also one of main things is soundcard. You need 192kHz ASIO soundcard. ASIO is a must for low delay. and good buffer.
For FM ,you might read, popular soundcards are Juli@, Marian Trace Alpha .. but also good onboard realtek soundcard can do good job. For perfect FM output vs your transmitter you'll need some callibrations.

And answer to your main question - It will be delay! Now only depend how much delay you can tolerte.
At maxuimum quality (4096) you can achive around 40-60ms. (did't measure precise recently)
Lower quality lower delay .. but not under ~20ms (512)...

callibrations in StereoTool, Juli@ sound or in fm transmitter?
my fm transmitter has separate hardwares: stereocoder and compressor limiter.
how it's working now: pc with m-audio sound and radioboss with ST plagin --- mixer --- compressor limiter --- stereocoder --- fm transmitter.
I think instead of compressor limiter and stereocoder will be 2nd pc?! (1st pc -- mixer -- 2nd pc -- fm transmitter).

Stereo coder and compressor you can remove

StereoTool replaces all that + rds.

so output you have (mixer or PC1) goes to PC2 (Juli@'s input) MPX Output from Juli@ goes directly to MPX input on transmitter.

is that mean callibration for perfect fm output? if yes tomorrow i'll try.
what output of juli@ will be MPX, L or R?
instruction for configuring ST for FM is here. do you have instruction for configuring juli@?

You can use L or R.
Important is to set MPX 'volume' to achive exactly 75kHz of deviation. You can measure that only with some analyzer.
Callibation is impoprtant but that is last thing you need to do.

Small addition: If you want a low latency monitoring channel, the stand alone version of Stereo Tool now offers a low latency (approx. 11 ms) monitoring output. Quality is not very good, but it should be suitable for monitoring. If you turn it on the CPU load will increase, so the CPU load may be too much.

I configured FM transmitter but could't configur sound card on ST. First time the delay was about 9-10 second and sound of musics was bad. Than configured and delay was 500ms but sound of musics still was bad than original. I need a manual to configur the sound card in ST i think because when i push the buttom "Bypass all" a music sounds good. help me. (sorry for bad english and i hope you understood me)