Thursday, July 3, 2008

Flex TX Audio...

I've made an MP3 containing two recordings. One recording is the TX audio from my SDR 1000, the other is the TX audio from my Flex 5000. To obtain this recording, send an email to jca1955 "at" and request the Flex 1 July 08 Audio test file. I'll send you the mp3.

Once you've received this file, take a listen. What do you think - is there a difference between the two? If so, which sounds better (first or second recording), and why?

The recordings were made using the same WAV file as the audio source for the transmitters (using the playback feature of the Flex Console WAVE tab), so this test is really just testing each radio's output from DAC through the TX mixer and the Driver and Final stages.

I used a second SDR 1000 to receive the RF from each of the two radios "under test" (by connecting each test radio's output to the input of my second 1000 via a BIG attenuator), and I made the recordings using this second radio (again, using the WAVE tab of the Flex Console - this time in Record mode).

TX setups were the same for the 1K and the 5K (EQ, etc.). TX Bandwidth was 100 Hz - 5 KHz.

Receive bandwidth (on the second flex 1000) was 100 Hz - 5 KHz. No RX EQ.

By the way...if you listen to the recordings, please do so before reading the comments (so that you're not prejudiced one way or the other). And I haven't identified which audio is from the 1K and which is from the 5K, because, again, I don't want to prejudice any views beforehand.



Greg said...

First Recording was better. The second one the same in frequency response and in amplitude but had some fuzziness to it that reduced the articulation/clarity to some degree. This is a very subjective view but does seem to match what I think I have been hearing on the air too. TNX fer the opportunity to hear side by side. 73 Greg

Jeff said...

Thanks, Greg. By the way, here's the order of the radios in the recording:

5000A: Radio number GJB
1000: Radio number BAR

(So that a casual glance of these comments by a reader doesn't reveal the order of the radios, I've "encrypted" the answer using ROT13 encryption (you can look this up on Wikipedia, and it'll give you the method for decoding).)