Satisfied with that, although I would like to get more grip on the spikes/peaks. The diodes solve that, but then the sound is to much distorted.
Here's my creation:
![Image](https://i.ibb.co/ZS4srsB/1669296694748.jpg)
a href picture
Sounds really natural Rev!reverend wrote: ↑Fri Nov 25, 2022 11:07 am This thread led me to digging out my 3-band processor which was built about 25 years ago. It splits the audio into bass (< 200 Hz), then an 'everything else' channel and a third band whcih deals with the pre-emphasis (i.e. the treble boost above 3 kHz). All 3 bands are seperately compressed and then the bass is clipped (just enough to cut off any overshoots) before the whole ensemble is passed to an overall clipper. It then feeds an analogue stereo encoder (which, having re-connected the whole thing has a 19 kHz carrier level that's about twice what it should be)
This recording is taken off-air, and shows (I think) how effective analogue processing can be. 3 different tracks/styles of music and it seems to work OK with all of them. There are some mp3 artefacts in the file due to the low bit rate, and you can hear the noise from the sound card that was feeding the audio coming up in the quiet passages when the compressor gain increases.
3banddemo.zip
The sad thing is that I don't have the full schematic for the circuit any moreI guess I could try and unpick the one remaining example I have left, but to be honest, with things such as StereoTool available, it seems kinda pointless.
From China? Beware of fakes!rigmo wrote: ↑Tue Jan 03, 2023 10:47 pmI see cost 5 usd in china?
https://www.ebay.com/itm/271040582551
Going back a few posts, I remembered that I built this FET limiter circuit, and fixed some nasty positive feedback around the internal capacitances of the FET and to the Op-Amp, causing it to oscillate.mike123 wrote: ↑Sun Nov 20, 2022 11:36 am Hi,
I build this limiter a while ago but have some questions.
If I'm informed correctly the 3k3 resistor (at the right site of the schematic) is for the release time?
I experimented with this resistor and increased the value to about 4k1.
I would like to change attack and release time.
I also disabled the two 1N4148 diodes because it's clipping way to much.
It might be they kick in too early, before the circuit starts limiting?
Also is there a way is disable the limiter function without bridging the circuit?
I would like to switch it on/off to check how much is actually limiting.
The circuit is also very picky which FET is used. I tried a 2N5458 because the 2N5459 was not available, but it did not work very well.
![]()
You got a source for those alfa rpar chips? Only one I can find is charging 6eur each. I can get a that2180 for less.
Albert H wrote: ↑Sun Dec 20, 2020 12:57 pm Here's a Veroboard layout that I've used a couple of time when I haven't had a PCB available. The clipper diodes can be reduced to two pairs, or you can make one pair BAT41s (Schottky diodes) to raise the clip point by 0.2V. It's cheap and simple, includes a 19kHz filter to prevent the blinking stereo indicator problem, has a stage of 15kHz filtering just to shave the top end off a bit, and provides 50µs pre-emphasis. Considering its simplicity, it sounds pretty good on the air, and costs almost nothing to make. The only slightly unusual component is the 22mH coil.
Mono Broadcast Processor.png
This has been used by lots of stations, and all seem to like it!