hvz said:
Great! I'll look forward to checking that out. Thanks, Hans.
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Stereo Tool 7.20 Release
- Thread starter oldiesstation
- Start date
Great! I'll look forward to checking that out. Thanks, Hans.
It's almost ready now - I just need to make it user configurable. A few questions to avoid adding more settings than needed:Grounded Grid said:
1. Am I right that the maximum allowed asymmetry on AM is 100 vs 150%?
2. Based on how things are connected, which side ends up where might be different (the signal might be inverted). So I suppose I should support increasing the peak level for either top and bottom?
Since sound cards cannot output more than 100%, I will have to lower the output level when asymmetry is introduced, so you need to increase the level going into the transmitter.
In the US, the maximum legal level is 125%...that may be different in other countries. There was a time here when there was no limit and one popular processor had a 300% setting! Whether a transmitter existed that could air that % is a good question. Depending on the gain of the transmitter, reducing the negative peaks to allow for the higher positives may or may not require amplification. I do know that it will be awkward if switching from 100% to 125% positive peaks causes a 25% reduction in the negative peaks. All known AM processors allow for the change in positive peaks to be made without impacting the level of the negative peaks. It seems that AM transmitters take something between +4 and +10dbm across 600 ohms for 100% modulation. The Trace Alpha is rated at +18dbu but I don't know how dbu compares to dbm so someone else will have to comment on that spec. The low pass filter will be needed...at least in this country where 10khz is our limit on AM. Most processors are good out to 9.5khz and have a steep dropoff between there and 10khz. we also use the 75us pre-emphasis curve for AM but it obviously doesn't apply above 10khz. So for AM, the multiband frequency staging would need to be based on the highest band topping out at 10khz. Anything beyond that would be "food for the filter" as we sometimes sayhvz said:
It's almost ready now - I just need to make it user configurable. A few questions to avoid adding more settings than needed:Grounded Grid said:
1. Am I right that the maximum allowed asymmetry on AM is 100 vs 150%?
Yes, the legal limit is 125%, but that's at the modulation monitor. Not all transmitters seem to work with those numbers, so the manufacturers allow some wiggle room. Most every processor I know of will go to 140-150%.
2. Based on how things are connected, which side ends up where might be different (the signal might be inverted). So I suppose I should support increasing the peak level for either top and bottom?
It's really up to the operator to connect polarity so that the transmitter properly plays assymetry. If it's backwards, we just reverse it ourselves. Breakaway offers a reversal flag in their setup... a nice, but unnecessary step. I would keep the negative as is (or lower).
Since sound cards cannot output more than 100%, I will have to lower the output level when asymmetry is introduced, so you need to increase the level going into the transmitter.
Understoon. No problem there.
Thanks, Hans. Much appreciated.
@Grounded Grid: This should do it.
http://forums.stereotool.com/viewtopic.php?f=14&t=4846&start=88
Note: I've changed a lot of things in this version (because I've rewritten lots of things to run on Linux), so this version is not yet tested thoroughly. You can test it but I wouldn't put it on-air yet.
http://forums.stereotool.com/viewtopic.php?f=14&t=4846&start=88
Note: I've changed a lot of things in this version (because I've rewritten lots of things to run on Linux), so this version is not yet tested thoroughly. You can test it but I wouldn't put it on-air yet.
Will do.
Thanks again!
Thanks again!
I am really intrigued by these PC-based processors and am seriously thinking about trying one. What sort of sound card is good for ST, etc.??
I use the Marian Trace Alpha,the ESI-Juli is a nice card as well.Those seem to be the most popular.The software seems to run fine on a Duo core E 8500.Some use I3,5,0r 7.I just installed an I7 in a rackmount.It just loafs,never breaks a sweat..You can go on the Stereo Tool forum and gets good info..Have fun...
The best one I know if the Marian Trace Alpha (or Trace Pro if you want digital AES/EBU input). The ESI Juli@ is very close, but it's not DC coupled (it has a highpass filter in the output which, if not compensated, can cause some peaks above 75 kHz modulation if it's not compensated). Stereo Tool has a tilt correction filter to compensate for this - but if you have the choice, not needing to compensate is always better.
If you just want to test it, even some on-board sound cards can work pretty well - I have a Realtek ALC269 in my laptop that I use for FM tests (it generates a reasonable quality composite signal). The biggest difference between this sound card and the Marian cards is that with the Marian, if I measure the signal with an FM analyzer, it shows over 90% of all measured values at 74 or 75 kHz and maybe 2% at 76 kHz (and 0% at 77), while with the Realtek I get 60% at 74-75 and some sporadic peaks upto 79 kHz (and no guarantee that there won't be higher ones). Which is probably good enough for doing some tests with a low power transmitter - it gives you a reasonable impression of how Stereo Tool will sound on-air.
If you just want to test it, even some on-board sound cards can work pretty well - I have a Realtek ALC269 in my laptop that I use for FM tests (it generates a reasonable quality composite signal). The biggest difference between this sound card and the Marian cards is that with the Marian, if I measure the signal with an FM analyzer, it shows over 90% of all measured values at 74 or 75 kHz and maybe 2% at 76 kHz (and 0% at 77), while with the Realtek I get 60% at 74-75 and some sporadic peaks upto 79 kHz (and no guarantee that there won't be higher ones). Which is probably good enough for doing some tests with a low power transmitter - it gives you a reasonable impression of how Stereo Tool will sound on-air.
Running ST for about a month now, so far, so good, using ESI Juli@ card, have measured, maybe I got a lucky card? no compensation needed. Still want to get my hands on a Marian card but can't find them.
Running about 65% CPU on Core2Duo E8500.
It's already attracted a little attention, sounds drastically different(better) than anything else in the market.
Running about 65% CPU on Core2Duo E8500.
It's already attracted a little attention, sounds drastically different(better) than anything else in the market.
stephend2 said:
Which station did you put it on? I'll listen next time I'm down.
7.24 just released. Several updates and new presets to test drive. ST Rocks!!
stephend2 said:
First thing I do with mine is clone the drive to an SSD. That cures a lot of the potential problems, especially if you also strip all the unnecessary stuff out, as you say. I have one that's been going over 3 years now... not a glitch.
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