Next SINUS project??

[radium98]

hailstorm thanks , i dont know if you can help me up ?

[Albert H]

Here is my latest test of the Sinus Limiter set up as a dual band processor. An active crossover is used which splits the audio at 250Hz.



The single band version sounds great on it's own so this was only an experiment. I'd got enough PCBs to make 5 boards. However with separate bands you can tweak the mix of high and low, and have different release rates per band to suit your audio preference.

As before the source audio file is the same, no EQ or pre-processing but Soundcloud have compressed it - so ignor any digital artifacts.

That sounds really tightly compressed, but big bass thumps don't dip the treble end - that's exactly how split band processing is meant to work. My experimental two-band version had the option to "tune" the changeover point between bands from around 110 Hz up to about 300 Hz. Extensive listening tests suggested that between 210 and 260 Hz is the best turnover point for most content. Your choice of 250Hz is pretty good.

I recently did a processor for AM radio, that (effectively) filtered off everything below 125 Hz, and fed it to a pretty brutal clipper. The clipper was followed by a further 125 hz lowpass filter to remove the harmonics that had been generated. The other two bands - 125 to 1250 Hz and 1250 Hz to 6500 Hz had 3: 1 compression followed by limiters, and all three bands were then recombined with a simple virtual earth mixer stage. With a bit of judicious level tweaking, the processor could make the AM station seem really loud without ever overmodulating, but also not to sound too "processed"! The frequency response was tweaked by a final lowpass filter stage to keep to within the permitted bandwidth, but the perceived audio quality wasn't "FM" quality, but certainly significantly better than most other stations on the AM band! It also had the advantage of tending to stay well above the noise floor at range. My original clients are very pleased with the results, and their listenership in their market has increased significantly - simply because they sound much better than the rest in their crowded market!

[radium98]

[LeeCavanagh]

Quick question , hope I have not already asked.
There are Toko 15khz filters on eBay, whilst they only have 2 pots you can turn (unlike the original ones that had three pots(, one has 7 pins the other 9, Would it be an acceptable choice ??

[shuffy]

Quick question , hope I have not already asked.
There are Toko 15khz filters on eBay, whilst they only have 2 pots you can turn (unlike the original ones that had three pots(, one has 7 pins the other 9, Would it be an acceptable choice ??

Yes Lee, I remember using the ones with 3 cores back in the day. They were 7 poles IIRC. These should work but probably fewer poles so might not be as sharp. They will need to see the right impedance on the inputs and outputs too, so you'll need to factor that into your buffering - I think they're 4k7.
One other thing, I have definitely wrecked the response of these by messing with the cores. I think they come pre-set!

[yellowbeard]

Yup don't twiddle the cores in them, they are set at the factory.

[LeeCavanagh]

Thanks both

[LeeCavanagh]

Is there a list of the component for sinus limiter ?? I need to place an order , if there is a BOM that would be awesome as can just upload to mouser or farnell. Or is it cheaper elsewhere ? I do have the common caps and resistors already

[LeeCavanagh]

How do I link together two mono sinus limiters for proper operation rather than just independent ?

[Albert H]

Link the cathodes (bar end) of D1 on each board. Loud sounds in either channel with then attenuate both channels equally, keeping the stereo image intact. However, you'll have to match the pinch-off voltages of both FETs and set the bias pretty much the same on both channels.

[LeeCavanagh]

Link the cathodes (bar end) of D1 on each board. Loud sounds in either channel with then attenuate both channels equally, keeping the stereo image intact. However, you'll have to match the pinch-off voltages of both FETs and set the bias pretty much the same on both channels.

Ok, great, thanks.