microphone tone control - Page 1
Forum section: electronics / beginners

author: Flump
author_rank: Frequent Contributor
timestamp: October 07, 2013, 03:56:40 pm
content: Hi allI built this amp which works very well but i wanted adjustabletone on ithttp://www.electroniq.net/audio?page=50so i built this bass and treble circuithttp://www.electronicecircuits.com/electronic-circuits/bass-treble-tone-control-circuitand had mic - amp - tone but the bass and treble circuitreally attenuated the volume from the amp and the trebledidnt make much difference.so i would like a simple tone (not bass and trebble)that doesnt attenuate the amps signal.can anyone suggest anything ?

author: w2aew
author_rank: Super Contributor
timestamp: October 07, 2013, 04:06:59 pm
content: Quote from: Flump on October 07, 2013, 03:56:40 pmThe preamp I did for the Astatic D104 mic might work for you. It offers bass and treble boost and cut.

author: Valueduser
author_rank: Contributor
timestamp: October 07, 2013, 04:46:37 pm
content: The tone circuit you linked to is always going to attenuate the signal given that it is a passive rc circuit. One thing to try would be to put another amplification stage after the eq to boost the attenuated signal.

author: Flump
author_rank: Frequent Contributor
timestamp: October 07, 2013, 10:09:14 pm
content: w2aew yours looks quite complicated for me not sure im upto that standard yet.Would yours work with different mic element types ?im currently using a dynamic mic with 430ohm impedancebut would like to try electret elements too.I wanted to build my amp into a project boxwith in and out sockets so i could try different mics.Thanks Valueduser i wasn't awarethat it would loose so much of the signal.

author: Valueduser
author_rank: Contributor
timestamp: October 07, 2013, 10:56:40 pm
content: What are you connecting the output of the amp to? It's possible that there is an impedance issue causing the signal loss.

author: Flump
author_rank: Frequent Contributor
timestamp: October 08, 2013, 05:13:18 pm
content: output of amp is going in to an amateur radio Valueduserthe original mic for the radio uses an electret element though

author: w2aew
author_rank: Super Contributor
timestamp: October 08, 2013, 05:37:29 pm
content: Quote from: Flump on October 07, 2013, 10:09:14 pmIf you break it down, it really isn't that complicated. More details are on this webpage:http://www.qsl.net/w2aew/myd104amp.htmlIt is basically the same tone-control circuit you showed, surrounded by two op amp stages (one is a preamp / impedance converter, and the other the buffer/gain stage around the tone control). Below the op amps in the schematic is simply the biasing network. Lower right is the shunt-regulated power supply. You could replace that with a 9V battery. You can make the input single ended if you desired. The output has some filtering to prevent RF from disrupting the circuit. I've used this circuit on my amateur radio for more than 10 years.

author: Paul Price
author_rank: Super Contributor
timestamp: October 08, 2013, 10:31:11 pm
content: That 150K in the emitter of the preamp (titled Use with Crystal/Ceramic Heads", first transistor is way too big a resistor value to work..perhaps a typo, looks like should be 150ohm?

author: w2aew
author_rank: Super Contributor
timestamp: October 09, 2013, 12:18:16 am
content: Quote from: Paul Price on October 08, 2013, 10:31:11 pmNot a typo, that's the original design from Astatic, and it works perfectly well with the high impedance crystal element in the D-104 microphone. This mic/preamp combination was purposely designed 40+ years ago to provide audio with a treble-peaked response to aide in intelligibility under noisy conditions.