Sotabeams Speech Compression

Trying out the sotabeams speech compressor on an FT818. I am impressed with the results. I have also recently bought an MX-P50M amplifier, and the speech compressor seems to give at least equal gain in signal strength.

Attached is a recording I made via the Hack Green WebSDR on 80m. Transmitting on 6W from the FT818 with compression turned on and then off.


I recon the speech compressor helps my FT 817 push through on ssb, but I did adjust the settings in the menu as well as internal settings for the compressor. Got an few local opinions on my AAAUUUDDDIIIOOO and left it at that. Great bit of kit.
vk5cz …

1 Like

Do you recall what settings you changed on the ft817?

1 Like

Hi Matthew,

a nice device. I am using such a compressor for about 3 years. But some times I have to switch it of because of distortions by rf. In a former thread (from Post 40 down) there was a discussion about.

73 Ludwig

1 Like

Menu NO 46 set to 35
Switch on the back of the standard 817 mic on No 1
Then once all hooked up made adjustment to the internal setting of P1 or P2 forgot but looking at the board P1 is for adjustment with Compression off and P2 is for Compression on. Maybe there were some instructions that came with the device I did it a few years ago. I just talked to a couple of my regular 80m ssb contacts and did the adjustment that way, they have to listen to me so good enough for them and country work.
My FT 817 is mostly used on CW.
vk5cz …


M0MZB, thanks for the impressive recording. Did you make sure the mic level is set correctly when the compressor is off? Listening to it, I have the feeling that this setting is not ok.

73, Peter - HB9PJT

It was years before I realised that I couldn’t get to full power at all until the ssb mic gain was set to 100. (it was also years before I realised that all bars off was full power not low power. If all else fails , read the manual)

My thoughts too. Mathew it should make an obvious difference when engaged but that seems too good. Probably Peter’s suggestion is right and the mic gain is set too low. Once you turn that up you will need to readjust the compressor.

You could leave it as is because it works but as these compressors do get upset by RF feedback in some circumstances, it is probably well worth doing the mic gain and resetting so you have a more viable system when you cannot use the compressor.

:+1: for very sensible use of an internet connected receiver. You can do these on-air tests with another ham but an internet connected receiver wont get bored and you can hear and judge the results yourself.

Thanks for the tip on the mic gain. I will give that a go. The effect did seem quite magical.

I was also amused to note that ZL1THH made the same mistake as I have made with the power setting. When the icon for power setting is not visible, the FT818 is set for full power…it makes sense as the icon includes the letter L for low power, but it took a couple of months of ownership before I noticed.

I did read the manual, but the power setting display isn’t exactly intuitive so I usually end up re-reading the manual before I use the rig… is it more bars are more power :ballot_box_with_check: or more bars are less power :x: but no bars is maximum power unless all the bars are flashing which in my case means I have forgotten the external battery! 73 Paul

Here is a good video about getting the most from the FT817/818!


1 Like

Not directly relevant but on my last activation a number of people said I was very quiet. As this was also my first with the IC-705 it occurred to me that perhaps I should have another go at reading the manual. :slight_smile: The result was I discovered the section where it talks you through adjusting the microphone and compressor levels.

The result was I had the microphone set far too low and the compressor wasn’t even turned on let alone set to the correct level. :slight_smile:

I’m hoping for better results on the next HF activation.




Hi Matt,
I hope this will be of help to you.



Thanks very much, that’s really helpful.

The ALC meter on the ft818nd doesn’t seem to make much sense…I thought ALC meters should read very few bars, but that seems to give a poor audio level. With ALC maxxed out, audio sounds much better.

1 Like

It depends on what you are doing. Not much ALC indication means the ALC system is not having to reduce the output to keep it at the level selected and a lot means the ALC is working hard to keep the output level at the set level. For something like speech, a lot of ALC indication means a high average output but could result in a more distorted, wider signal. For digi modes with varying amplitude signals like PSK, you want zero ALC indication, it’s less of a problem for constant envelope signals.

The best way to set your mic gain, ALC level etc. is to do what the owners manual says.

The trouble is that there is no level adjustment on the output side of the compressor. Ideally you would adjust the output level so that the peak output is the same whether you have the compressor on or off. The gain control changing the level of drive into the compressor chip is not really in the right place. Well, not in the version I have (purchased at Friedrichshafen 2016).