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| Multipath? https://forums.stereotool.com/viewtopic.php?t=4972 |
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| Author: | HadYourPhil [ Fri Sep 13, 2013 8:07 pm ] |
| Post subject: | Multipath? |
I hear a weird high frequency effect on my ST-processed staion. Songs with a lot of high end tend to "picket fence" when listened to in a moving car. I don't hear this when I have the Optimod on. The pilot injection is 9.5% and it is very stable. I've turned on the "Multipath Clipper" but I don't hear any difference. Anyone have any suggestions?? |
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| Author: | hvz [ Fri Sep 13, 2013 11:21 pm ] |
| Post subject: | Re: Multipath? |
Can you try what happens if you turn on Stokkemask? This will damage the highs and stereo a bit. But if it helps we can search for a solution from there. Other thing to try: There's a slider to reduce the maximum demodulated peaks (they can go upto 160% without that). Try what happens if you reduce it to - say - 120%. This does not have much effect on the sound. O, and it only happens in a moving car?? |
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| Author: | HadYourPhil [ Mon Sep 16, 2013 4:07 pm ] |
| Post subject: | Re: Multipath? |
I will try the Stokkemask. And thank you for explaining the "Maximum Demodulated Peaks" function. I may try that first. Yes, only heard in a moving car. Mine is a 2001 Lexus RX300. It has diversity reception for FM. (edit) I just turned on the demodulated peaks function. It came on at 125%, so I'll leave it there. |
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| Author: | hvz [ Tue Sep 17, 2013 1:10 am ] |
| Post subject: | Re: Multipath? |
You might want to try 100%. Not a good idea if you want good quality sound, but to test if it causes this issue. Afterwards increase it to around 120-130 (so 125 is fine) again. |
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| Author: | HadYourPhil [ Tue Sep 17, 2013 8:34 pm ] |
| Post subject: | Re: Multipath? |
The demod clipper seemed to help although I didn't think it did the high end audio any favors. I just turned it off and will try the Stokkemask FM today. What is the difference between the Stokkemask FM and the Multipath clipper? I had the Multipath clipper on but couldn't detect any effect on the audio. Last question: The overshoot setting in the Stokkemask... What's a good setting? |
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| Author: | HadYourPhil [ Wed Sep 18, 2013 6:00 pm ] |
| Post subject: | Re: Multipath? |
No answers? The Stokkemask seems to work very well in eliminating the "picket fence" effect, BTW. |
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| Author: | hvz [ Thu Sep 19, 2013 12:04 am ] |
| Post subject: | Re: Multipath? |
Ah good. "Stokkemask" should help to reduce multipath effects (Leif Claessen told me the same thing this week at the IBC, he said that it works much better than SSB stereo for example). However it does reduce the audio quality. If you use a higher than the standard value, the filter is less strict - you will get more multipath issues but a better audio quality. I don't know what the best setting is - the lowest is mandatory here in the Netherlands where the FM dial is completely filled up with nearly no empty space left - but nowhere else. To reduce the audio effects, it helps to reduce stereo separation ("Stereo Multiplier" in the Stereo Boost section) a bit, for example to 70% or so. If it really helps that much, I should probably look at it again to see if I can improve the filter further to reduce the effect it has on the audio - until now I thought it would only be used in the Netherlands and I didn't want to spend too much time on it. |
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| Author: | HadYourPhil [ Thu Sep 19, 2013 6:54 pm ] |
| Post subject: | Re: Multipath? |
It does help. I don't think I've heard the picket fencing since I turned it on. Here are the settings under Stereo Boost: Boost Strength: 3.23 I had to turn that down initially because I was getting artifacts in voice. Maximum Amplitude: 2.63 Have not touched that adjustment. Multiplier: I reduced it from 1.00 to .78 The overshoot setting on Stokkemask, I've turned it up to 3.92 Hope this helps you... |
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| Author: | HadYourPhil [ Tue Sep 24, 2013 3:09 pm ] |
| Post subject: | Re: Multipath? |
Nothing new? I turned the "small overshoots" up to 4.66, not really having any idea what it does. |
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| Author: | hvz [ Tue Sep 24, 2013 3:12 pm ] |
| Post subject: | Re: Multipath? |
Stokkemask is mandatory in the Netherlands, at value 0 - but it hurts the audio quality a bit. Raising the level makes the filter less strict (it basically moves the red lines up if you look in the RF spectrum), which makes the RF signal a bit wider but also allows more stereo separation. So: Higher = better quality audio, but more multipath issues. |
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