Stereo Tool

Good to see Phil on board and always enjoy bob's post.Phil,when you try the song,would you please post the results? With Breakaway,the M 192 had to be modified to stop the overshoots.If the stock M192 doesn't overshoot in ST,that is as bob says a game changer. Most ST users use the Marian trace alpha or the esi juli , it seems. Both outstanding cards for the money....

I did see a few overshoots today of 1% and the occasional 2% overshoot, so I backed down the output a fraction of a dB. That cured the overshoot. I can live with a dB, maybe even two, as this is still far superior to the 8200 and 8300 I have on line now.

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1 or 2% is less than 1/4 db--and the human ear has a tough time detecting less than 1db. That backdown is a non-issue. The thing about Stereo Tool is that the sound quality will put your Orban gear to shame. You're in for a treat my friend!

I brought in Three Dog Night's Best Of CD and tried "Black and White". No overshoot. I tried every song on that CD (playing their intros) and on rare occasions I would see 106%. I tested two Century 21 CD's full of oldies also. Same thing. Rarely 106%. On two occasions in my testing, one being "Superstition" by Stevie Wonder, I saw 107%. I am very pleased with the peak control in Stereo Tool. And, I've just registered it with the idea of sticking it on the air on Tuesday.

I still have unanswered questions about ST and I'll bet I'll have more.

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By overshoot, do you mean that the meter hangs on 100% but occasionally jumps as high as 107%? If so, that requires the average to be at 93% to stay legal. That would be a deal breaker for me. With the Trace Alpha, it sits at 100% and never ever overshoots even 1%. The tradeoff is that level of performance comes with a $300 price tag.

Legal is 105% with stereo pilot. Occasional overshoots are not a problem. They were rare, as in 1-2 a minute. The 107% happened twice in 30+ minutes.

My meter hangs at 104-105% like it is glued there. I'm using an Inovonics 531 Modulation Analyzer.
I was unable to get the Trace Alpha card in a timely fashion, which seems to mirror other people's experience. And, although there is a modification given for the M-Audio card, I have not done that.

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We improve things by making them worse.

So the overshoot is 2% max with 1% more common. That would work for me. My Inovonics 530 is glued in place like it's seeing a test tone--truly amazing, and as noted, "tighter" than any commercial processor I've played with, yet it sounds more open. Amazing product.

Curious to know how the 104-105% figure was arrived at. FCC rule 73.1570 b (2) states that this applies only to SCA signals. Never have seen this interpreted as to allow modulation recovery of the stereo pilot. It is routinely applied to RDS signals however. The extra 0.5% per 1% was based on a 67khz and a 92khz subcarrier both operating at 10% (total of 20%), which allowed for an extra 10% total modulation. The goal was to encourage stations to implement SCA operation without fear of main channel loudness loss. The minimum sound difference the human ear can detect is 1db, which corresponds to the 10% loss using 2 SCA's.

(2) FM stations. The total modulation must not exceed 100 percent on
peaks of frequent reoccurrence referenced to 75 kHz deviation. However,
stations providing subsidiary communications services using subcarriers
under provisions of § 73.319 concurrently with the broadcasting of
stereophonic or monophonic programs may increase the peak modulation
deviation as follows:

(i) The total peak modulation may be increased 0.5 percent for each 1.0
percent subcarrier injection modulation.

(ii) In no event may the modulation of the carrier exceed 110 percent
(82.5 kHz peak deviation).

The reference to 73.319 further confirms that the stereo pilot subcarrier is not included in this category by stating :

(a) The technical specifications in this Section apply to all
transmissions of FM multiplex subcarriers except those used for
stereophonic sound broadcasts under the provisions of § 73.322.

I'm not an FCC lawyer or anything remotely close but I've worked (and currently work) for large broadcast organizations that use every legal strategy to maximize modulation while staying 2-3% under the limit. I feel confident that if this were permitted, they would have been using it since the Report and Order that allows it was issued on April 9 1984.

Having no idea where I first heard the 105% limit, I did research on the FCC's site and checked with the DOE of a group. Also with a former FCC official and a couple of other engineers. I was wrong. It's 100%. However... The DOE said he has not heard of any overmodulation citations in over 20 years. All the stations in my market run over 100%. Personally, I have no problem running 105%. I am convinced that high modulation is not high (so to speak) on the FCC's worry list. They're more concerned with "reassigning" spectrum, tower registration and public file issues. With FM competition being the way it is, I'm going to modulate as high as I can within reasonable limits.

Back to Stereo Tool. I may pull the card out and add the 470 uf capacitors recommended, just for the heck of it. The low end response goes easily to 30 Hz, using the ST tone generator. The square wave looks flat as a board. Maybe M-Audio has upgraded their card?

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I have 2 of those cards but have re-purposed them (one for Adobe Audition and one for the automation system sound card) so I'll probably not be testing them on ST, but your results are encouraging Phil. Before going to the Marian card, I did do the 470uf mod and it made absolutely no difference in controlling the 20% or so "Black And White" overshoot. Based on your results (which are far different from mine while using Breakaway), I'm gravitating toward the "it's a Breakaway issue" more than blaming the sound card. I have 3 Trace Alpha cards so my next two builds will likely use them but I may revisit the M-Audio card and give it a spin. If that happens, I'll share the results here. Thanks for trying Black And White on your setup and good luck as you launch ST on a real station and reset the market's competitive reference point

Actually, the intro to "Black and White" was frequently a point or two low...

Interesting to see comments on the Breakaway processor and possible overshoot issues. That would be a deal breaker for me. I'd like to hear Breakaway, but so far I've had no luck downloading a test version. I haven't looked for several days though, being more interested in fooling around with Stereo Tool.

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We improve things by making them worse.