audio volume control on the ascom

[M3HME]

help please how do I reduce the audio on my ascom even right down it's still way too loud.

[EI7GMB]

I am just about of experimenting at it. My target probably will be an "active" speaker with analog volume control (nothing big, just an bipolar transistor and potentiometer) but for the time being I would put just an resistor in series with the speaker. If I could get some schematics then probably just a simple change of SMD resistor in level circuit in audio section will be the solution.

[M3HME]

hi thanks for your solution will give it a go.

[EI7GMB]

My most effective solution to this day is just to put the speaker facing down to the desk.... Ahh... and I use this popular old Phillips/Simoco speaker what usually comes with FM1000 - much better than Peiker one, what comes along with Ascom.

If you are going to use an resistor in series then try to get at least 1 watt ones cause dissipated power would quickly fry "standard" 0.125w and don't forget that this is only a temporary (not proper) fix. What I would try is any bipolar NPN transistor (in TO220 enclosure) with a potentiometer (anything around 1k to 10k should do) between Collector and Base in series with a speaker where incoming audio signal is on Collector and speaker is between Emitter and Ground wire. There is a plenty of space to fit it into speaker and enjoy real analog volume control.

Power on volume level as you know yourself is more than loud so still vast amount of regulation should be available with this thing.

[EI7GMB]

Ok, here comes a _proper_ mod for Ascom SE550 excessive volume problem. It is quick and easy.

Open up SE(same)550 and look for inverter board. Locate 8k2 resistor (SMD component printed as 822) nearby chassis mount point. See the picture - remove component shown (red arrow).



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Now solder 2 wires instead, solder a 10k potentiometer and find your own "startup" volume. In my case 1k is just ok but your preferences could be different. Measure, get a closest resistor value, solder in and thats it.



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Now assemble back your Ascom and pray it would start up Enjoy!

Just in case you would like to know "how it works?". Ascom employs common TDA2003 amplifier. Audio is fed on pin1 throught capacitor and input level is set by resistor draining excess to ground - this is the component what should be modified according to user preference.

I was also trying to utilize spare line to get external "analogue" volume control but reserved line (it supposed to be not connected and clean, FYI its pin5 on external subD connector) gathers too much rubbish into audio. Much shorter way is to cut track of microphone pin2 (not used facility of can connect) and solder signal straight into it. But for the time begin I have nice and clean Ascom microphone and don't wanna to drill any holes on it yet but if I would have spare, then linear volume control could be easy incorporated into it.[/img]

[G3PTU]

If you go down the road of the addtional volume control in the speaker; as advised, small resiters are useless, even carbon variables will commit sueside at some unopertune moment. Its real watts you are disipating.
Use a Wire wound potentiohmeter (try a rally) anything of say 10hms should do. If it does not reduce the Volume sufficantly in a striaght series mode, form a potentiohmer (Speaker to Slider! Do not short the audio feed line at minimum)
They are still available ex stock including HiFi shops. They tend to be expensive - £10. Try Cpc, they have pages full of canidates. Rochdale Sante Vincentes rally 12th November
David G3PTU