Extra Stereo Widening on FM channels?

[Saket]

Hello FMs,

I use a Pioneer SX-434 Stereo Receiver as my tuning equipment. Its a real nice thing from past and I admire every bit of it. I would just like ask a question or rather an experience that I would like to share and ask your views about it too.
I have noticed that the stereo separation on the Tuner is pretty good. To elaborate, when you tune manually (of course, its the only option), you catch the station first in mono. While fine tuning when it changes to stereo reception, there is a lot of difference in the sound. There is much more wideness and separation is really nice.
On the other hand, when we play our devices, say like a tunrtable or other stereo equipments, of course the sound is stereo, but the widening is not like that of the tuner.
I would like to ask if the stereo fm operators, do they employ some techniques of more widening for more of stereo effect? like adding bass to one channel, treble to other, just like reprocessing?
Have you guys also experienced it? or is it just me!

Saket

 

[Hiten]

A stylus in microgroove may have trouble separating two channels specially at lower and little upper lower range of frequencies more so on louder passages of the music. Good Stereo separation depends on cutting engineer of vinyls and music. Imagine huge excursions a stylus has to make if one channel has loud low frequency music. Some gurus say that at lower end of the frequency range stereo does not matter. (i.e. we cant distinguish between stereo and mono.) So engineer make them mono. So all in all all as they say almost all amplification methods have pluses and minuses and one has to live with them.
For wider stereo effect if I remember there were some preamps in old days along with echo effect (Cosmic ?) Not sure though.
Regards

 

[Saket]

First of all Thanks Hiten for looking into it. I completely get the theory of stylus movements and agree too that stereo effects are almost nil on low frequency sounds, but my question would be that even the FM operators would have a source....my guess would be digital these days but just wanted to know if they add any more techniques while broadcasting to add to their stereo effect (& hence their reputation??). Like any effects processing to right & left channels, etc?

Thanks & regards,
Saket

 

[jls001]

I would like to ask if the stereo fm operators, do they employ some techniques of more widening for more of stereo effect?

Stereo expander is used by some FM channels. It is done in the audio processor.

Disadvantage: it increases multipath effect which reduces signal strength, and therefore, reach.

 

[Saket]

Thanks Jls,

So this is it...I always thought there must be something in it. Could you please share more knowledge on this topic? As you said, it weakens the signal, so it is mostly used in smaller cities covering smaller areas as compared to larger ones?

Thanks,
Saket

 

[Hiten]

Oh! I thought you were talking about vinyls. Don't know about FM transmission but once in a digital format there are tremendous possibilities. Adobe Audition has tons of corrections and effects (like widening stereo) which can be applied easily.
Regards

 

[jls001]

Could you please share more knowledge on this topic? As you said, it weakens the signal, so it is mostly used in smaller cities covering smaller areas as compared to larger

I wouldn't know the nitty-gritties of how stereo is widened as it is done in the audio processor.

In any line-of-sight VHF radio transmission including FM transmission, the signal that reaches the receiver is a combination of multiple signals that get reflected from buildings, hills, etc. When the signals reach out of phase, they get cancelled partially or even fully and leads to poor reception. This is multipath effect. Widening stereo increases this undesirable effect.

Just for info, two popular FM audio processors:

1) Omnia 6FM
2) Orban Optimod 8585

 

[Saket]

Oh! I thought you were talking about vinyls. Don't know about FM transmission but once in a digital format there are tremendous possibilities. Adobe Audition has tons of corrections and effects (like widening stereo) which can be applied easily.
Regards

Of course, In digital music, there is no limitation on stereo widening theoretically whereas this is somewhat limited with LPs. But as far as I know, its is not used much because whatever the human ears perceive can be achieved with LPs too. Also, too much of stereo widening can result in loss in the mid range & vocals which in turn is a big disappointment for those who look for that 'warm analog sound'.
And thanks for the name of this Adobe software, I have worked quite some time on soundforge & some other sound mixing softwares but never knew about this.

Thanks & regards,
Saket