SP-1a Speech Processor

[Truthcaster 77]

The SP1-A can be made to work fantastically well. I have used them off and on since 1991 when I first got to play around with an AR3500. My mentor owned a few of them and that is the radio that made it possible for the RCI2950 to come to market years latter. The problem I think with a lot of users today is that they are into HIFI and eSSB and for the most part 99% of compression devices kill the hi fidelity and audio bandwidth. You could make a hi fidelity compression device but you have to add a lot more complexity to it. So they are just not that popular today. If you can ignore that though it is a really good way to increase average talk power to the point that your approaching the same amount of improvement you would get with a 100w external amplifier. Combine the two (100-200W amp) and compression or band pass rf clipping and some compression it is in practical terms a lot like having 500-600 watts.

I have some devices that do audio compression alone some that use all pass network and they convert the audio to rf before filtering, clipping, compression and converting it back to audio. and some that have 8 band eq+compression. All of them can sound decent to fantastic on AM and kick butt on SSB. On AM often less is more!

A Ten-Tec 715 can sound really good better than a lot of radio's built in processing.

None of this stuff is idiot approved you can mess anything up if you do not know what your doing.

You can still buy circuits based on the early industry Symetra System from early broadcast days. If you feed your audio through that alone you can improve effective talk power. Feeding it through that before feeding into a compressor also works great. AKA Phase Rotating Asymmetry Eliminator! http://www.w3am.com/8poleapf.html

 

[Eldorado828]

Bump

I just installed one of the sp1a speech processors in a ranger rci-2950dx6 so I'll see how it works out in this radio.
I had looked at other ways to give it a little increase in audio then I remembered having a couple of these so I gave it a shot. It's a hot little device so setting it up is a little tricky to get the audio just right.

 

[Onelasttime]

As long as you understand it is a clipping and compressing the audio all is good. As long as you are ok with that they kick butt! So opposite of eSSB or Aysmetric Modulation at 300%.

Less Comm has down some crazy buildings using a CP1 to Drive the SP1-A or maybe the other way around.

I like to run assyemtry and compression on AM and SSB with a little delay so little delay and echo you would never hear it or know I am running it. Not only great for breaking pile ups on SSB but when using an amplifier.

If I need to power up an amp before I even go there I power up the Ten Tec 715 or like. If that does not get the job done then I power up the amp. On the other hand if your just talking local and AM only that is when you flip NPC 120%.LOL

 

[711]

As long as you understand it is a clipping and compressing the audio all is good. As long as you are ok with that they kick butt! So opposite of eSSB or Aysmetric Modulation at 300%.

Less Comm has down some crazy buildings using a CP1 to Drive the SP1-A or maybe the other way around.

I like to run assyemtry and compression on AM and SSB with a little delay so little delay and echo you would never hear it or know I am running it. Not only great for breaking pile ups on SSB but when using an amplifier.

If I need to power up an amp before I even go there I power up the Ten Tec 715 or like. If that does not get the job done then I power up the amp. On the other hand if your just talking local and AM only that is when you flip NPC 120%.LOL

The CP1 did its clipping in the 4558 mic preamp feedback loop, the SP1a would most likely be inserted before the CP1 but to me it would be counter productive. The 4558’s purpose is to bring the mic’s signal up to line level to drive the Series pass regulator aka modulator. You could drive the modulator into the rails with a “hot” audio signal and it would start to clip but it would sound like poop. Mic type and drive would be the main considerations when determining if you need an SP1a. Power mic and talking style gets you into the same place imo