I use an old Hewlett-Packard PDA with an SD card as a source for my Part 15 transmitter, but the output volume was very low, so I bought a TC-780LC from Phonopreamps through Amazon. I put it in service today and the result is amazing. It now matches the volume of my Arrakis console. Very pleased.
I post this only as a suggestion for those looking to boost the source volume for their transmitters.
Does this amp have any EQ settings? Reason being that it could even help with the Talking House AM Transmitter. Maybe get that sound even better for AM (if we can keep our hobby long enough now).
No, it boasts a 20dB gain with no loss of frequency response, so I suspect you would need an equalizer to tweak the signal. I was impressed with the increase in volume, but I think that's all it will do.
In my day they started the trend of mixing consumer grade audio equipment, sometimes called semi-pro equipment, with professional audio equipment and the need was created for what they started calling "buffer" amplifiers.
This is because of the audio line differences between the two types of equipment.
Those audio line differences include two main categories:
1) Line level - the consumer equipment is designed for a much lower level than pro equipment, the inputs/outputs require/produce -10 dB signals;
Professional audio equipment requires/produces 0 dB signals, which is fully 10 dB higher than consumer line level.
2.) Line Configuration - audio lines exist as either un-balanced (2-wire) or balanced (3-wire) configuration, and coupling from one type to the other requires specialized knowledge and is often done incorrectly by those who don't understand how to design the proper matching circuits.
We could throw in a third category of complexity invlolved when mixing and matching audio equipment, that being impedance matching, but we'll save that for another day.
What Morningdj has is a buffer amplifier that boosts in a range that will match levels between a consumer level and a professional level.
I didn't realize all those things were involved with a buffer amplifier. Since I use it with an old HP PDA, I thought the low level was because using ear phones would be too loud and potentially harm the ears. Whatever the reason, this new unit works really well and accompished what I needed. It has many other applications--my usage was a new one for the distributor.
Morningdj said: "Earphones."
Aha.
Earphone outputs have whole other properties different from any of the type lines discussed in my previous Tech Note.
Except that earphone outputs to come into the category of "impedance" which I did mention.
I'm getting in under my head.
The "pro" equipment I have used here and elsewhere operate at +4db levels.
Most include a selector for +4/-10 db levels for compatibility.
Could explain how on another forum someone had a transmitter that had variable output and thus kept it at 5mW. Anyway they were having audio issues with their transmitter an wanted to know why his mixer/compressor limiter would sound like it was distorted. Well if your trying to run it into a transmiter that is ment for consumer level and your driving it at +4DB and it should be driven at a -10 it explains why its distorted. Even a Ramsey could do this if its set to consummer level and you try and connect it to a professional processor pumping out +10DB. It could also explain any hiss you could hear when you have the audio levels turned way down. Goo points to remember.