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Total posts : 45366Another useful and comprehensive review from you, Tim. Nice work.
One observation: the 240 µV/m field at a 3-meter distance from this setup when it used a 10″ stiff wire transmit antenna oriented in the vertical plane probably was measured when the antenna on your FI meter was oriented in the horizontal plane.
Results earlier in your review showed about a 48% increase in the field you measured when the transmit antenna was operating in the horizontal plane (other things equal).
Could the field when using the 10″ wire transmit antenna oriented in the horizontal plane be closer to 355 µV/m?
Total posts : 45366Any idea about this? I do not see anything in the specs or I may have missed it. Thanks, John
Total posts : 45366Great review Tim.
The EDM I used to own had trouble with hum – obviously they’ve solved that probem. They also appear to have solved the signal bleedover into adjacent channels that I experienced.
I assume that there is no documentation associated with the transmitter telling U.S. purchasers that the power trimmer has to be at the absolute lowest position, and use the rubber duck antenna to be legal. Few of the people who would normally purchase this transmitter would have the necessary test equipment to verify that they are operating legally.
All in all, this appears to be a nudge nudge wink wink transmitter. It can operate legally, but it’s highly unlikely that most purchasing it would do so (either knowingly or not). Unless, of course, they read your review.
Total posts : 45366Seems this, like the Decade, is really HI FI sound…..and from the photos on the website all regular through hole components like the Decade also.
I’m interested, but worried about not being certified for use in Canada.
Wonder if it would be better in the long run to get the rubber duck antenna instead of a 10″ wire as the rubber duck is a 50ohm match for the output.
Oh yeah, That new Stones album is great! Liked you used that to test!
Mark
Total posts : 45366I thought I had done a horizontal test with that 10″ antenna, but I could not interpret that in my notes when I got back to my office. By the time I got to that test I was about frozen! Certainly the field strength will be greater when both antennas are in the same plane. Although, most people will have it vertical I would think.
I will look through my notes and see. I was pretty sure I had that piece of data.
I was really just trying to see if it would operate as a legal Part 15 transmitter on this last test. Really, to get busted in this case the agent would have to be checking vertical and horizontal and that may not be too likely.
Anyway, I’ll have a look, but yes, clearly, the horizontal reading would be higher.
TIB
Total posts : 45366Of the two Part 15 transmitter supplied antennas I’ve had none of them have been “real” rubber duck antennas. They have been simply a plastic antenna structure with a piece of wire inside. Basically a plastic rod with a hole up the center with a wire inside connected to the center pin of the connector and nothing connected to the shield side at all. Basically, a wire antenna in a plastic tube. The antenna you can order from EDM sure looks like the same one to me.
But of course a better match would almost certainly mean greater output which would make Part 15 operation unlikely.
TIB
Total posts : 45366I can’t remember the documentation right now, but I do believe there was some reference either on the website or with the instructions (link at the end of the review) that said something about low power for Part 15 but didn’t go into much detail.
I think it’s a *wink wink* deal anyway, as is soldeering in ONE part reallly a “kit”? And what’s the specific rule about kits anyway? There just seemed to be some “paperwork” details that seemd a little sketchy to me, but a nice operating and sounding transmitter, that’s for sure.
Clearly, if you just bought it and started using it, you’d be way over Part 15 limits.
TIB
Total posts : 45366Website info (from the instructions pdf) states they are set for 75 kHz deviation from the factory.
It is worth noting that the documentation on the website is not for the exact same transmitter. It appears the models have changed a bit over the years, and there are several different models. The documentation shows the ability to adjust this, but the transmitter I purchased does not have this adjustment, but other models might, or might not.
TIB
Total posts : 45366Field strength was measured at High Power and with the supplied antenna but I wonder two things:
Is the transmitter 75 uS pre emphasis or 50 uS as with most of the Chinese imported in the USA are?
And finally what was the Range of this transmitter at its High Power mode compared to the Low Power mode which was closer to part 15. This would be nice to know for any attempt to start a separate Hobby Broadcasting service.
All in all sounds like a transmitter that has a great sound quality and could easily meet or surpass Album Rock standard so therefore I’d like to look into this more closely.
Honestly if I had the extra cash I’d like to experiment with this one.
Total posts : 45366I haven’t been able to find any data on pre-emphasis for the EDM transmmitters. However, to my ear the audio sounded basically identical played from the mixer directly, as compared to listening through the EDM transmitter. I noticed no tinnyness or odd equalization. I listened for quite some time to both rock and roll and jazz piano. Both sounded exceptionally good.
I didn’t do any range testing at all for several reasons. Perhaps the most important is that it’s winter here and it was 4 degrees, and I didn’t feel like getting out my snow shoes (yes, we actually have them) and trudging around a field checking range. And also, because every transmitter operating at the legal limit is going to have the same range. 250 uV/m is what it is, not matter the device generating it. Operating this or any other transmitter at any higher output would not be legal. Should any other power level become legal in the future, range between transmitters would again be comparable if they were all operating at the maximum limit available. This does allow for a rather extensive range of output so might meet future needs should things change.
This particular transmitter has bascially an infinite range of output within it’s limits as there’s the hi/lo switch that gives two different ranges, then the adjustable trimmer that lets you vary the power within the switch selected range.
I will say, that if I were going to run a station with this transmitter some processing would be necessary. Don’t get me wrong, it sounds great, but modulation levels are not leveled out at all. Quiet passages will drop it to near nothing, loud segments will blast it way above 100%. To find a spot where it didn’t surpass 100% left things pretty quiet most of the time. Some processing to smooth things out would be an improvement.
But this is perhaps one of it’s advantages in the audiophile market, wide dynamic range.
If you’re listening to your own music for your own personal use (and apparently a lot of buyers of the EDM transmitters buy them for this purpose) you can enjoy a pretty full dynamic range from loud to soft. But it you’re “broadcasting” you generally want a more consistent level.
I could not find any information anywhere as to where this transmitter was built. One generally assumes China but I could usually find an indication of that on the circuit boards. Nothing on this one. Also no country of Origin as required on products imported into the USA.
I’ve tested quite a few FM transmitters, so far all were certified except this one. Intersting to note that nearly all the certified units I tested were well over the legal limit.
This little bugger is very well made, although a bit more “industrial” compared to a BV or C. Crane that’s more “consumer” looking (e.g. plastic).
I do see the other Part 15 site is planning a review on this in the future. Perhaps he will be able to answer more questions, as his was supplied to him by the company rather than purchased at retail, so he will likely talk with them to learn more.
I’m also amused that the SourceFM website talks about these EDM transmitters and states “Not approved by the FCC and operating them is a violation of Federal law with a penalty in the thousands of dollars and even jail time.” Which is not really true. If you have this transmitter set for the legal limit (low switch setting and trimmer all the way down to low, and a short antenna) you’ll be at the Part 15 limit. This is where the responsibility of the owner/operator ends. Actually operating it improperly would be a violation. That would be the only possible violation for a user. Otherwise the only people who may get in trouble would be EDM, for selling a transmitter that is not certified, IF in fact it was deemed to NOT be a real kit. But YOU would not be in trouble for OWNING it.
It also comes with a four year warranty!
TIB
Total posts : 45366Kind of makes you wonder why a distributor doesn’t get these certified (running at the lowest power level possible) and then resell them legally. After all, that’s what Decade did with the CM-10.
Total posts : 45366From Reply 9: Website info (from the instructions pdf) states they are set for 75 kHz deviation from the factory. …
An earlier post in this thread inquired about the pre-emphasis this EDM transmitter used.
The pre-emphasis (if any) supplied internally by a transmitter depends on its circuit design and adjustment.
However the carrier deviation of an FM transmitter depends on the audio spectrum of the source, its input level at the transmitter, and the pre-emphasis used (wherever located).
Even if a transmitter has been designed/adjusted to add 75 µs audio pre-emphasis, that would not enable its manufacturer to set it for +/-75 kHz deviation for all input conditions, when shipped from the factory.
Total posts : 45366The certification process is quite expensive. Also to sell as a certified transmitter all the user adjustable power controls would have to be disabled and they would have to be sold with either a built in antenna or an antenna with a non-standard connector.
As I’ve poked around trying to learn more about these it seems they actually are made in South Africa, and they’ve been around for quite a few years, obviously ghoing through model and design changes and updates over the years.
They’re quite popular with the Christmas light animation folks, too.
I’m assuming that they’re able to sell them because they’re kits? I know there has been some discussion of the legality of Part 15 transmitter kits, and soldering on one part is hardly a kit. But it looks like they’ve been doing it for many many years. This is a transmitter that seems to be quite popular world wide.
TIB
Total posts : 45366Yes. I was clearly bewildered at the moment. Plus, I’m getting information off an older instruction pdf. Their information isn’t presented as clearly as one would like, not updated, and I suspect some translation issues as well. What I was trying to refer to is on this page:
http://www.edmdesign.com/manuals/STEREO-TX-LCD.pdf
But there is no mention anyplace about pre-emphasis. I like to think that if I was listening to 50 us pre-emphasis I would have been able to notice audibly. I listened over the air to recordings I know very very well and they sounded completely perfect to me.
Maybe you can glean more info from that pdf.
TIB
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