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In the Forum: Off Air Audio
In the Thread: Where are our good Tuners?
Post Subject: Bandwidth and DACsPosted by mats on: 6/6/2011
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 Romy the Cat wrote:


Interesting, mats.

The unit is not “complex device with many settings”. All those settings have own meaning and if you know how a tuner works then there is absolutely nothing menacing in those adjustments. You went for RBRX1? I wonder why? I think RX1 has all set of futures that necessary for people like you and RBRX1 is more for relaying applications. Were you attracted by RBRX1’s ability to be used as a standalone DAC? BTW, how good that DAC when is used from external digital source, your Goldmund transport for instance?

Regarding the tuner. I never had it and I do not know what to expect. David was threading me that I will get one to test but it never materialized. Perhaps you mats will be traveling to Boston and you would bring your RBRX1 in? Then we will be able to see how RBRX1 stands.

There are a few things that I am very interested. They keep talking about the adjustable bandwidth but they never published the bandwidth of the window. I have plenty of good tuners that can do from 100KHz to 650kHz. What I would be interested is to see how RBRX1 will perform again other tuner with good selectivity at the SAME IF bandwidth. It is not difficult to get a good reception by narrowing the IF window. The problem is that with narrowing intermediate frequency we truncate the side band and losing a lot of audio quality, not to saying the stereo quality. With the way how the stations are seeded in US FM dial I think the 500kH is more or less optimal IM bandwidth, at least in Boston where we have each 0.2-04Meg a deferent station.

Another thing is the quality of that digital multiplex decoder. There are no modulations in decoder any more but pure sound. How all of it DSP processing affect sound no one know. At this matter we do not even know how many bits that 48K out has. I hope it has 24 but they do not say…. I would rather to have them to run A/D not 24/192 but 32/352. They then would be able to output 88K and have highest bits that can be eaten by DSP.

Of cause it is all literature and the quality of sound altogether is something that interests me. All those “over 50 parameters” (or better to say some of them) are relevant to set the tuner in optimism receiving condition for a given signal. Then there is the actual quality of sound that tuner is potent to show.  This variable is not known to me so far. I have seen online audiophiles were trying to compare RBRX1 to different tuners and found that MR-78 was more preferable.  That is funny as I do not consider the MR-78 worth any attrition, it is not to mention that audiophiles are generally understand Sound as much as Sarah Palin understand multiplication table….

It would be also interesting to run RBRX1 into external DAC and to see if you will be able to get better result. I do not know what kind digital signal they output. Most like it is Mono right after decoder with 19kH defeated. Anyhow, you can compare it with your Lavvy and get some idea about the quality of RBRX1’s output stage.

Rgs, Romy the Cat



Romy,


At this point I prefer the sound of the outboard DAC, Lavry DA-11.  I imagine your full blown Lavry would be excellent.
I have used the RBRX1 at its currently widest IF setting, which is 157kHz.
Agree with you about wanting the full 88K output.  Perhaps that is in the future.
When it comes to sound, I am still struggling to describe the RBRX1.  Different recordings sound very different.  So far I tend to think of it as a neutral window.  
The RBRX1 is light, and travels well.  Let me know if your local dealer is not responsive.

Mats

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