I have an Inovonics 235 feeding a Sstran amt 5000. Over the past couple of years, I've tried to play it by ear regarding the modulation. I just got an Inovonics 520 AM mod monitor off of eBay. On the 235 I am able to adjust the negative output from zero to over 100%. I am unable to get 125% positive modulation. When I adjust the pos output on the 235, I'm not seeing much of an increase or decrease through the monitor. The positive modulation stays around 100%-110%. There is a slight decrease on the positive when I turn the neg mod to 0%. I can't get the positive to adjust to 0%. Any ideas on what could be wrong. Thanks
Audio is fed to 235 as follows: Arrakis Arc 8 console --->Whirlwind IMP Line Combiner --->235
The SsTran AMT5000 has it's own built in audio processing. Unless you have bypassed this, pretty much no matter what you put into the trnasmitter is going to be dealt with by this. So even if you try to pump in more audio the built in limited and compression is knocking it down to the transmitters pre-set limits. I'm sure the internal processing is set up to maintain a pretty even modulation level except in the case of extreme changes in level (hence your consistent 100-110% even with level changes -- the built in processing is evening out the modulation for you).
I have no personal experience with that transmitter. Maybe it's a simple matter to deactivate or bypass the internal processor, but if you haven't done that, there's your trouble.
TIB
I forget which direction you turn the compression knob on the SSTran to bypass the internal processing. IIRC its fully counter-clockwise.
I have both an AMT5000 and AMT3000 which both have the same processing controls over the audio.
From left to right:
Audio Input Gain sets the amount of audio being fed into the transmitter and there's no reason to bypass it because you can adjust it up or down no matter what other equipment is connected;
Modulation Control sets the top modulation peak into the transmitter, acting as a limiter to prevent over-modulation. To bypass it set it 100% CLOCKWISE and use your processing gear to set the peak modulation. This is probably the control that is preventing your processore from doing its thing. Set it 100% CW and you should be in control;
Compressor Control bypass is achieved by setting the control Counter Clockwise (CCW) which gives no compression.
Let us know if this solves the problem.
I have the Gain and Modulation both set fully CW and compression fully counter CW. That should disable the on board processing. I'm guessing my 235 is faulty. I have the positive output on the 235 turned all they way up and still don't have any positive mod readings near 125%
Let's take a look at the input to the Innovonics 235...
If it's set for 0 dB or +4 dB balanced input, which would be typical of a professional audio device...
What type of signal is driving that input?'
If it's -10 dB unbalanced consumer level that may be the weak link in your chain.
Is it even posible to modulate the AMT5000 to 125%? I know there are some transmitters that just won't do it.
Just run audio into the transmitter -- no processing set on in the transmitter, no external processing. Just audio. Preferably a test tone, but music would work. Watch your mod monitor and see if you can obtain 125% + modulation with raw audio. This should be easy to do if it's possible. After all, processors aren't needed to reach 125%, they're needed to control those peaks to a max of 125%.
That would tell you a lot 🙂
TIB
I have +4 db balanced pro audio going into the 235. The input polarity is connected properly.
The Amt 5000 can achieve 125% with an external asymmetrical processor according to SSTRAN.
My experience with Inovonics has been really good. Stuff built like a tank. I would look elsewhere for your problem.
Worst case you can send it in to Inovonics, they aren't too pricey on repairs. Also keep in mind not all audio programming will be aysmetrical.