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Stereo signal problems
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zurn
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Joined: 08 Apr 2005
Posts: 16
Location: Albuquerque, NM

Post Stereo signal problems Reply with quote
Hi there,

I recently got my PCS MAX card set up and working great, but lately i've noticed something odd: during playback of some tracks, the stereo signal cuts on and off. When playback is stopped or paused, the signal is steady and unchanged.

i've tried adjusting the power level and volume levels, but this doesn't seem to make any difference (unless the vol is all the way down!)

Any suggestions?

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-steve
Mon Jun 06, 2005 3:33 pm View user's profile Send private message
pcs
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Joined: 18 Jan 2002
Posts: 3063
Location: Radio Land

Post Reply with quote
In winamp or sound card setting open equializer and pull down all sliders above 15KHz, this is what FM radio standards call for anyhow (cut
above 15KHz).

This will fix the problem.

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Best regards,
Marko - PCS Electronics
--------------------------------------------------------
Turn your PC into a FM radio station!
http://www.pcs-electronics.com
fax +386 4 2316 128
Mon Jun 06, 2005 3:38 pm View user's profile Send private message Visit poster's website
zurn
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Joined: 08 Apr 2005
Posts: 16
Location: Albuquerque, NM

Post Reply with quote
Thanks for the tip, but i've got some questions (being pretty dumb about equalizers! )

I use a playback software called Media Center, and it has an eq like winamp, but i'm pretty sure that if i even have it turned on, it's probably flat. However, i'll check (not at home right now).

Otherwise, by "over 15 khz" do you just mean the one slider for 16k? That's all that mine has as well. Should that be at zero?

thanks again!

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-steve
Mon Jun 06, 2005 8:35 pm View user's profile Send private message
pcs
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Joined: 18 Jan 2002
Posts: 3063
Location: Radio Land

Post Reply with quote
Yep, pull that one down all the way. You won't hear any difference, but
stereo will be ok.

_________________
Best regards,
Marko - PCS Electronics
--------------------------------------------------------
Turn your PC into a FM radio station!
http://www.pcs-electronics.com
fax +386 4 2316 128
Mon Jun 06, 2005 10:49 pm View user's profile Send private message Visit poster's website
zurn
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Joined: 08 Apr 2005
Posts: 16
Location: Albuquerque, NM

Post Reply with quote
pcs wrote:
Yep, pull that one down all the way. You won't hear any difference, but
stereo will be ok.


Well, i tried that, but to no avail: certain tracks still cut out, while others are fine--even others that seem more...shall i say, sonically intense

any other ideas?

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-steve
Tue Jun 07, 2005 2:57 pm View user's profile Send private message
pcs
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Joined: 18 Jan 2002
Posts: 3063
Location: Radio Land

Post Reply with quote
Ok, than use one of the programs such as MBL-4 or winamp
plugin rocksteady.

There shouldn't be any material around 19KHz or it will
interfere with stereo pilot.

You're probably running your audio a bit too loud.

_________________
Best regards,
Marko - PCS Electronics
--------------------------------------------------------
Turn your PC into a FM radio station!
http://www.pcs-electronics.com
fax +386 4 2316 128
Tue Jun 07, 2005 3:01 pm View user's profile Send private message Visit poster's website
zurn
New registered user
New registered user


Joined: 08 Apr 2005
Posts: 16
Location: Albuquerque, NM

Post Reply with quote
pcs wrote:
Ok, than use one of the programs such as MBL-4 or winamp
plugin rocksteady.

There shouldn't be any material around 19KHz or it will
interfere with stereo pilot.

You're probably running your audio a bit too loud.


Could be, but turning the volume down a bit doesn't help until it's very low--lower than other regular stations.

Media Center does use Replay gain, which adjusts volume for each track (based on a score from previous analysis)...but i'm pretty sure i tried it with that off.

I'll try again, and maybe test with winamp/rocksteady and see what happens.

thanks again,

_________________
-steve
Tue Jun 07, 2005 3:37 pm View user's profile Send private message
ripsem
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Joined: 16 Aug 2008
Posts: 3

Post Reply with quote
I'm having this problem with my se3+ that I just purchased. My source material (mp3 on a cd has been filtered on the computer to just under 15 khz) but the SE3 + has a 15 khz filter anyway , but the volume is about a third of what other stations are by the time I turn the volume down low enough on my cd player so it does not interfere with the stereo signal . I am using a pll proII that did have a pro II encoder and it worked pretty good , but I thought the SE3 + would be a nice upgrade , but I can't run my audio input very loud with out disrupting the stereo signal . I was curious if I could increase the mpx input level on the transmitter board because from the factory that veronica had setup it was about right in the center of it's range but now with the se3+ it is just barely turned up from as low as it will go . I am going to send this in an email once I find the best place to send it . Also , the stereo seperation doesn't seem to have any effect . There is very little crosstalk regardless of how I adjust the 2 pots. I can not make it increase or decrease but it's hardly there anyway.
Sat Aug 16, 2008 1:25 am View user's profile Send private message
pcs
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Joined: 18 Jan 2002
Posts: 3063
Location: Radio Land

Post Reply with quote
Regarding stereo separation, if its hardly there its working well.

Regarding audio content around 19KHz, the thing is any content
appearing around 19KHz will interfere with stereo pilot and cause
stereo to cut out periodically. While cheap stereo encoders have
15KHz filters this is not enough to entirely eliminate the problem.
Decent stereo encoders such as SE3000 or SE5000 have not only
15KHz low pass filter that is a lot sharper than the one found in
value stereo encoders (any cheap stereo encoder out there, not just
se3+) but also an extra notch filter centered exactly at 19KHz.
This arrangement provides 40-60dB attenuation at 19KHz truly
eliminating the problem. As a comparison a simple EQ usually found
in sound card settings may yield 6-12 db attenuation above 15KHz.
While helpful this is not enough to completely eliminate the problem.
MBL and similar PC based DSP programs help a lot with this problem.

Regarding loudness, broadcasters use complicated and expensive
compressors/sound conditioners. Certainly you don't expect a 50 euro
board to match that? SE3+ does not have any compressor on board.
However, se3000+ and se5000+ do and they come very close to the
performance of pro broadcasters, in filtering and audio level.

There's nothing wrong with saving money and choosing budget solutions,
but don't expect this to yield equal performance.

There is no such thing as free lunch, get SE3000 AN+ or SE5000 DSP+
and experience the difference in sound quality.

_________________
Best regards,
Marko - PCS Electronics
--------------------------------------------------------
Turn your PC into a FM radio station!
http://www.pcs-electronics.com
fax +386 4 2316 128
Sat Aug 16, 2008 12:33 pm View user's profile Send private message Visit poster's website
ripsem
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Joined: 16 Aug 2008
Posts: 3

Post Reply with quote
my material is all compressed and limited . I have run the material through a behringer 9024 and for the filtering I have used cool edit 2000 and ran it through an fft filter , I can then spectrum analyze the material and see that everything above 14.5 khz (thats what I have the pass frequency set to) is now down to about -100 db , I have also played a cd from my cd player and recorded it in cool edit and then analyze that and the higher frequency stuff is then about -95 db , and the previous encoder sounded pretty good , I just wanted the 15 khz filter and the mpx filter , which I don't believe my encoder had . Anyway , I was just wondering if that stereo signal is a result of to much input into the decoder because I lower the input volume and then it's ok . What I did was just raised the mpx input slightly to get enough volume so it is usable . I do realize I am not going to match a large station , I was more just curious if this was operating as it should , because I thought it would be a step up from my old encoder but I don't think it was , although it did improve the stereo sound a little bit I believe. So , I was not finding any fault with the encoder , I was just asking if it sounded as though it was working properly. The only other question I have at this time is , I want 75 Us pre emphasis , so do I slip the jumpers onto the pins next to 75 Us on the board ? They were on next to the 50 but I placed them next to the 75 . I again want to state I was not finding fault , I realize the other encoders are better , but I don't need the onboard compressor , I was mainly looking for the filtering . Is it possible to just make a filter and put it inline before the encoder . I don't believe I'm getting enough frequency around 19 khz for it to effect the stereo , but then again , I don't know how much is allowed , but I know it is very low , like -95 db. Thank you for your help , and I still think I got a pretty good deal on the unit , as I said before , I was not finding fault , I was just curious if you felt the unit was working as it should.
Sat Aug 16, 2008 11:56 pm View user's profile Send private message
pcs
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Joined: 18 Jan 2002
Posts: 3063
Location: Radio Land

Post Reply with quote
Yes, possibly you were overdriving the inputs.

If you are in US/Canada you should set jumpers to 75 usec.
I believe south america as well subscribes to 75 usec.

You can of course place 15KHz filters in front of your stereo encoder,
thatt will contribute to your signal quality. 19KHz notch filter helps
as well, of course.

_________________
Best regards,
Marko - PCS Electronics
--------------------------------------------------------
Turn your PC into a FM radio station!
http://www.pcs-electronics.com
fax +386 4 2316 128
Mon Aug 18, 2008 11:05 pm View user's profile Send private message Visit poster's website
ripsem
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New registered user


Joined: 16 Aug 2008
Posts: 3

Post Reply with quote
I have tried to find info on making such a filter or purchasing one , would you have any suggestions ? As far as making one I would almost need like layout and schematic , etc , because I don't have the knowledge to just build from a schematic . I have noticed there is a lot more definition in the sound , because I am hearing minute sounds that I wasn't hearing previously , but that also means I believe I am hearing defects in my mp3 material. I would really like the filter info , if you could get it . Is that something you could make and sell ? Thanks for your help.
Wed Aug 20, 2008 1:50 am View user's profile Send private message
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