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Hi guys.
I’ve been trying Breakaway Broadcast Processor but I have a question regarding the PEQ.
Does adjusting the PEQ also adjusting (removing gain) cause the overall peak audio level coming out of Breakaway to increase?
I’m not interesting in using it in stereo but I am interested in using it as a good mono processor with pre-emphasis for a small 1W (yes 1000mw) LPFM transmitter.
Currently I’m using MLB4 standalone which has pre-emphasis etc… and for mono works reasonably well.
My problem is needing a PEQ after the processor to compensate for sound card frequency response. That’s why I had a look at BBP.
On my current setup, if I install a PEQ after MBL4 everytime I try to cut gain the actual overall peak audio level can overshot.
How I tested this was audio player—- virtual audio cable—mbl4—virtual audio cable— audio editor peak level meter and frequency analyser. When I actually remove gain, I get peak level increase. I’m guessing this is something to do with group delay or phase problems, something a little over my head.
So does BBP compensate for this if cutting gain using the PEQ in BBP so the actually peak output decreases instead of increase?
Is there anything on the Internet that offers real-time tilt/PEQ just by its self?
Cheers,
Gavin,
New Zealand.Hi Gavin!
The PEQ is designed to solve the problem you’re having.
If EQ is applied to a peak limited signal, overshoots will occur.
However, EQ’ing a signal one way, and then re-EQ’ing with the INVERSE of that, should cause flat frequency response, and the peaks should disappear.You’ll need an oscilloscope to set it up properly, but it should be doable. Please follow this guide:
http://www.claessonedwards.com/index.ph … &Itemid=83
The Tilt correction in BBP is "minimum phase" (that is, it causes phase shift), whereas the PEQ is linear phase (that is, it causes no phase shift). When correcting EQ, one must use an EQ with the same phase response as the EQ causing the problem, or the overshoots will not disappear.
This all sounds more complicated than it is, though. If you hook up a scope and get the QuickSweep and squarewaves right, it should Just Work ™.
I don’t know of any other audio processing software that offers Tilt and PEQ. Kind of mindboggling considering that sound cards usually need it — in fact I only know ONE sound card that is perfect out of the box, and it’s the Marian Trace Alpha.
Best,
///LeifWish that card was easier to procure in the U>S>..Poor distribution or poor demand for it in the U>S(one of the 2)…there’s bound to be a another card with straight DC output.
[quote author=”Q106″]Wish that card was easier to procure in the U>S>..Poor distribution or poor demand for it in the U>S(one of the 2)…there’s bound to be a another card with straight DC output.[/quote]
One would think so, but I’ve never found one. Let me know if you do.
///Leif
I’ll just get the scope and set the modded m_audio card i have.(Have an extra one if someone is interested).Latest asio release is very good and dam clean.Any date for the hardware box yet?
Hi Gavin, if as you said, you are transmitting only in Mono (I assume with RDS?) you only use 20hz-16Khz of your soundcard’s frequency spectrum for your audio and a small notch at 57Khz. Any soundcard which is 192Khz capable should be pretty much close to perfect this low down in the spectrum maybe rolling off after 40-50khz but not usually earlier than that. If you have an HF rolloff which is giving you a low RDS level, just increase the RDS level a bit, much less of a headache than messing with PEQ. For mono, I really can’t understand why you’d need PEQ unless you have a REALLY poor soundcard. Even your Audigy 2ZS (how do I know that??!!) should be fine up to 20khz.
If you were running stereo of course this would be different, you do need close to perfect linear response curve up to 60khz, but for mono, as long as you are linear to 16khz, your audio is not affected, then even if you have a large drop, like say 12dB up at 57Khz, then just increase the RDS level by 12dB.
Tilt on the other hand is important to have correct, mono or stereo, RDS or no RDS. BBP is the only program to offer this feature.
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