My first post in this thread was written with the comparison of transmitter range in mind because this was being discussed in the other thread. I agree that the choice of a transmitter for an application should be made by comparing other factors as were mentioned in the previous posts.
Laboratory or bench testing if done properly is an effective method of assessing the performance of a transmitter when on the air. For (an extreme) example suppose a bench test of a part 15 AM transmitter shows an output power of 10 mW and an audio frequency response of 300 to 3000 Hz and THD of 15%. I wouldn't bother to air test this unless this was intended to be a baby monitor.
That being said there are situations where bench testing fails to account for operating factors found with radiating a signal. One I have seen several times is a transmitter which performs well with a dummy load but will generate spurious signals when connected to an antenna. This could result from the RF getting into the circuitry or the antenna differing in impedance from the dummy load. I have seen both causes.
ArtisanRadio skillfully listed several factors which affect transmitter performance and the benefit of bench testing is that many of the factors which are not controllable in an on the air test can be controlled on the bench test. This is both good and bad. Good because the tests are well defined and can be replicated, and bad because unknown factors not present in the bench test can adversely affect the transmitter performance when on the air.
Equipment designers generally begin with a thorough bench test and then test the device in the intended operating environment and mode. There is benefit to both bench testing and operational testing and if done properly these are complimentary.
Neil
It is generally true that listening is subjective, because knowing a bit about the physics of sound is not an everyday skill.
But there are formal and objective studies which can equip the ear to be very objective. Music theory is one branch. Audio acoustic engineering another.
And all listeners are dependent on a healthy set of ears. I have found that many seemingly dull listeners actually have hearing impairments and are not hearing all of what is present.
Probably the most common taste that I've noticed among the untrained, is the love of good bass response. If it thumps, it is good for them.
A direct comparison between the AMT 5000 and AMT 3000 using the same external loading coil and antenna for both should be possible since the manufacturer says it is possible, and has made provisions for using the same loading coil and antenna combination with both transmitters. The only problem is that the manufacturer has not yet worked out the details of using his loading coil and antenna combination with the AMT 5000, and wants his customers wishing to do so to "experiment" to work out the details themselves. He, in fact, is now telling his customers to forget about the loading coil and antenna combination on his website and use the internal loading coil in the AMT 5000 instead. Sounds like bait-and-switch to me. Most of the SSTRAN customers are not engineers, and they really need detailed instructions for properly using their transmitters.
When I did a Sunday sermon about audio I meant to conclude by talking about the audio quality of both SSTran transmitters. Impeccable.
The word "peccable" is built around the words peck or pick, "to peck something to pieces" or "pick something apart," so IMpeccable means that there is nothing to pick at because it's that good.
All I am trying to say by writing a whole book about it is that the audio quality of the two AMT/ssTran transmitters is excellent. It is the highest distortion free wide-frequency-response fully professional audio achievable with amplitude modulation.
But it would be possible to make any transmitter sound bad with poorly wired equipment or inferior audio samples.
P.S. I don't get the "bait and switch" claim. I understand the "bait," and it's the best bait you can buy, but I never got my switch. What am I waiting for?
"A direct comparison between the AMT 5000 and AMT 3000 using the same external loading coil and antenna for both should be possible since the manufacturer says it is possible"
It has been proven and documented that a real world test using the same external antenna system on the 3K and 5K units has been performed and as such, provided two different results..one providing a better signal than the other, and that was done with a cage monopole antenna (window pane). Carl can describe this antenna in more detail.
IMO...we can expect to see two different results from tests done with a 3 meter antenna setup as well.
And IMO....case closed as to "To Compare Or Not To Compare".
RFB