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Off Air Audio
Topic: I am an FM pessimist nowadays…

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Posted by dfa2124 on 04-08-2017
As there was talk on the BW Broadcast RBRX1 receiver here, I thought this might be of interest:

I have bought a new DSP-based tuner, and it is unlike any other I have used before. I had sort of distantly lusted after the BW Broadcast RBRX1, but never thought I'd be able to afford one. Well this has since been superseded by the RBRX Encore. Normally I wouldn't have been able to afford this sort of thing, but I had a bit of a windfall recently and so used the opportunity to snap it up. The device is actually a professional rebroadcasting receiver. Although it is extremely sophisticated with many options buried in menus, it is actually very logical and intuitive to use and I can make adjustments quickly as needed. It has dual DSP-based tuners. I had to buy adapters for the audio cables (it has balanced XLR inputs only) and for the coax plug (it uses a 50 ohm BNC input) but it was easy to set up for monitoring. The receiver is designed to work with the most challenging of reception conditions and rebroadcast your signal at the highest possible quality, so I knew it was going to be ideal for DXing.

Most of the options useful for me are in the PRESETS menu, and I go to the TUNER 1 submenu (this is the tuner I have the aerial hooked up to) where you can tune up and down in 100 kHz steps, adjust the de-emphasis (off/50 uS/75 uS), if filter (auto/fixed - the latter has 15 bandwidths to choose from ranging from 56 kHz to 311 kHz), stereo blend adjustments, stereo improvement with traditional high blend or fmsi (FM stereo improvement) which uses DSP in a similar manner to the Sony XDR-F1HD to kill the extra hiss with many parameters adjustable, soft mute on/off, again with lots of possible adjustments. The display on the left which gives info about the received signal includes RDS data like PS name, PI code and Radiotext (this doesn't seem to work properly) as well as received signal strength in dBuV, multipath %, modulation %, ultrasonic noise, softmute, high cut, stereo blend, high blend, and fmsi parameters such as low band, 2.2 kHz band, 5 kHz band and high band. In short it makes one of those Revoxes look plain and simple in comparison! Adjustments are made using the central rotary knob, which means that you can use this knob to tune up & down the band, with no muting. Very nice. The extended coverage down to 65 MHz mentioned in the PDF specifications is actually not included yet but will apparently be added in a future firmware update. I don't know if the DAB and HD options involve extra hardware or whether this will also be included in a firmware update. I would also hope that there will be an option to adjust the tuning steps e.g. 10, 30, 50 or 100 kHz.

For information, the available IF bandwidths available are: 56, 64, 72, 84, 114, 133, 151, 168, 184, 200, 217, 236, 254, 287 and 311 kHz. Very comprehensive and useful!

The receiver has even more flexibility if it is connected to your LAN, but that isn't really practical for my set up. In theory I could set it up to monitor, say 87.6 MHz, and send me an email when a signal is received, so it could be used as a DX warning device! Having said that, it has what I think may be a software glitch as it occasionally reboots itself at random times, so I'm going to try and update the firmware via ethernet hook-up later this week.

For DXing this receiver is a dream machine in every way. With the IF bandwidth set to Auto it isn't as good as the XDR-F1HD at fending off splatter from adjacent signals 100 kHz away, but using the fixed bandwidth of 56 kHz I think it is actually slightly better in this respect. For general tuning around and DXing I use a fixed bandwidth of 114 kHz as this is a good compromise for good audio quality, excellent selectivity, and easy RDS decoding. If you want to use the receiver as an audiophile listening device you can choose the Measure mode, which bypasses all of the DSP and gives you an unmolested clean FM signal at the widest 311 kHz bandwidth. On BBC Radios 3 and 4 in this mode the audio quality is fantastic, with a bit of a different character to the Kenwood L-1000T, but not inferior. Bear in mind however, that using this mode you will get multiplex noise even on empty channels. The only other tuner I have that offers similar DX performance is the Sony XDR-F1HD but the audio on this is inferior and it is far less flexible. The 8 presets can all have different setting stored in them so it's almost like having 8 different tuners as they can be set up for different purposes.

So this device is extremely flexible and sophisticated and it shows what can be done with the latest chipset and DSP software. More info on this receiver can be found at the links below:


http://www.bwbroadcast.com/bwbroadcast/rbrx-encore/64/product

http://www.bwbroadcast.com/files/downloads/BWB-RBRXencore.pdf

https://www.youtube.com/watch?v=YSb-jAsbfPw

Manual: http://www.bwbroadcast.com/files/downloads/rbrx%20user%20manual%20v0.26%20rev2a.pdf

PS: my unit has had an issue where it randomly reboots itself on occasion so I have sent it back to BW Broadcast for fixing. I suspect it is a software bug.


Regards,
Nick, Whitchurch, Hampshire, UK
Posted by Romy the Cat on 04-09-2017
For sure an interesting devise, thank you Nick. I personally do not like HD broadcasting. Some ideas that they have for FM is “interesting” but in reality, it is hard to know what actuals sound is possible get from the FM stages of this unit. I am kind of drifting away from FM screen. Here is Boston until rissesntly we had a very interesting broadcasting option but the station that did it went very much south, layoff all cable engineers and now they run very bad quality programing. If a few years back juts after life broadcasts the broadcast engineers contacted me and were asking about the quality of Sound then today if you call to the station and tell them then they are having left channel 6.5dB higher modulation then right channel then they would advise to “move your ass at the couch 3 feet closer to right corner”. You understand that in this environment there is nothing to fish. The digital streaming does offers some possibility but it is 192K in the best case plus with no control over the sources of the broadcast (and a few other reasons) the result very frequently is not good. I use digital streaming for work, or table radio listening but I tend do not play it over main playback
Posted by dfa2124 on 04-12-2017
Hi again Romy. I have never tried many of the 'super tuners' such as the Sansui TU-X1, Accuphase T-1100, Yamaha CT-7000 etc so I have no idea how this newer BW Broadcast unit would compare with them. Luckily the BBC still broadcast some very good quality programmes, such as Radio 3's 'Late Junction'. The best 'traditional' tuner I have is probably the Kenwood L-1000T, and I know that it would benefit from a service and alignment. A big part of the appeal to me of the Encore is the combination of superb sound quality and (possibly) unrivalled DX performance. It would certainly be a very interesting read to see how the Encore would compare with some of the tuner greats of the past.

As for the radio scene in Boston, WCRB now streams in AAC at 256 kb/s here:

http://audio.wgbh.org:8006/wcrb-itunes-256k

It sounds pretty good through the DAC in my amp. It's not lossless but it might be worth a try in your system.
Posted by Romy the Cat on 04-12-2017
Nick, the link you point out is WCRB programing, they run mostly crap music in major keys from mp3 servers. The BSO broadcasts have a different location and then best of them are in 192K. You might get it from here for instance, it On Demand Concert Broadcast Service: 
 
https://www.bso.org/Medias?playlist=wgbh 
 
I do not like the sound quality in there but it is what it is. Good for office listening.

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