Hello - New Member

[VikingRanger]

Hi!

Found this forum whilst searching the WWW for ideas regarding Audio Compression and Limiters for home construction (being unwilling to hand over a leg and kidney for an Optimod)

I've also just finished building a "Cranefly" LPAM transmitter for use here with some vintage radios, seems the original design is attributable to a member here also - interesting little unit, and my first introduction to AM transmitters built without valves

Loosely involved with some "independent" radio stations in the very early 90s in Stevenage, and had a little bit to do with helping an RSL station at a youth club some time ago, but otherwise main interests are Amateur Radio, and operating AM transmitters on the air.

Lots for me to read up here, so thanks to one and all for posting so many interesting threads.

Cheers
Sean

[ehsanspicedigital]

Oooohh Albert's not going to be happy when he reads your wanting to buy an Optimod

After I took Albert's Advice I haven't looked back, Ill let Albert explain why Optimod's are a bad choice!

Anyways, Welcome. There is definitely a lot to read up on here

[EFR]

Oh, fellow AM dude!

Optimod has an nice case, everything inside is good for parts.

[VikingRanger]

Ohh, I dont think there's any fear of my buying an Optimod. I much prefer to build.

Theres nothing in the workshop here I cannot repair..... I do not want that to change

[Albert H]

For AM, you need a really good lowpass filter at 7kHz, a slow-acting AGC to average out different sources, a compressor / limiter (possibly two or three-band), and an overshoot clipper with filter just to shave off the stuff that's too fast for the limiter.

I came up with some basic processing for AM (it's on this site in the Anorak Corner) and many people have either built it or used it as a basis for their own tweaked versions.

Getting a good sound on AM generally requires some mild bass boost and I like to "brighten" the audio by applying a progressive treble boost from around 1kHz upwards, which is then tamed at the top end by the overall lowpass filter.

DO NOT consider the Radio Caroline approach - they insist that their Broadcast Warehouse DSPX is wonderful, but it sounds like the sound is coming through several layers of cotton wool or lots of socks! I told Peter Moores that they had "super-sock" modulation, and all he could say was that the response was "compliant". They really are wasting their time, sounding that bad.