For XM or Sirius users ... sound quality is equivalent to what kbps MP3?

[blessingx]

I never know if Sat Radio should go in the separates or computer forum, anyway...

As everyone knows, the marketing departments call it "CD-quality" when in market-speak, and "digital-quality" when in .... well market-speak.

I was curious to get a realistic comparison to other lossy compression. The trial webstream is of lower quality than the sat broadcasts, and I know the HE-AAC used (I believe by both) is a little difficult to compare (and I know of no OS X encoder or player to test myself), plus the kbps fluctuates per station, etc.

I heard one reviewer on Amazon compare it to 96 kbps MP3 (no mention of encoder, etc.). Those of you with XM or Sirius, is this what I should realistically expect if I decide to buy? How about compared to a good FM signal?

 

[Stephonovich]

I've demo'd them before, and I'd say it compares to a very high quality FM station, or maybe a 160KBPS MP3 or so. This was with speakers, and not really audiophile quality, but that was my impression. Very crisp, punchy, and fun.

 

[KyPeN]

I have XM, so my opinions are based upon that. OPINIONS for those who think I am wrong.

I would compare it to a 128 kbs LAME mp3.

Talk stations, 96 is being generous.

I can honestly say, I am happy with my XM, and would buy it again. The sound quality is what I expected, no better, no worse, but the variety is so immense.

 

[blessingx]

Just called Sirius as I was going to get their "life-time" plan (subscription fee of $500 which would be about 3.5 years compared to their other plans). Get this...the life-time plan is for the specific radio, not the user. If the radio breaks one day out of one year warranty or car gets broken into day after you buy it or you ever want to upgrade... you're out of luck.

Checked by calling back. Kinda a scam if you ask me. One rep said it was the customers fault ("it's right there in black and white"), then admitted it's ending in December because of all the problems it's causing.

The other said things like.. "well I wouldn't recommend it if you're not planning on keeping your car for life" (err what does that mean?)... and if you buy at Best Buy and get 10 years of extended warranty ("it's usually only $10 per") "you can make the unit last!"... and "our techs said radio components of this quality should work for 6-10 years".

But I did find out they may start selling a 4 channel (music, kids, etc.) video also unit in January "in response to XM, which may be going into VoIP".

So screw them... and curious what's coming up next.

 

[stevewm]

XM uses AAC-HE with SBR (Spectral Band Replication)

Bitrate ranges anywhere from 30kbps to 50kbps on music channels. Its said the talk channels run around around 16kbps. With the traffic and weather channels being yet lower, probably around 8 or less. Traffic and weather channels also run at a 32khz sample rate.. (music and talk run at 44khz)

AAC tends to perform better in lower bitrates according to many tests done at hydrogen audio. FYI: This was also the reason is was picked as the standard codec for digital shortwave radio, which runs a very low bitrates around 20kbps. (DRM or Digital Radio Mondiale is the name for this standard)


Sirius uses PAC (Perceptual Audio Coding) at around the same bitrates.

Both services have a high-end cutoff at 15khz.

As for which sounds better, its completely subjective. Just like any lossy compression some content compresses better. I know on XM the dance/electronica channels always seem to sound good no matter what. While on the otherhand the heavy metal channel (XMLM, 42) you can hear the compression artifacts very easily...

 

[stevesurf]

Quote:

Originally Posted by stevewm XM uses AAC-HE with SBR (Spectral Band Replication) Bitrate ranges anywhere from 30kbps to 50kbps on music channels.

...and higher (they may top out at 96kbps for XM. XM's bit rate seems to be higher for one group of channels; lower for another channel grouping. I personally prefer Sirius' sound quality; it is more consistent throughout the range.

 

[joelongwood]

I recently (last week) got XM with the original SkyFi 1 receiver. I've read that the SkyFi 2 and the new Polk XM Tuner enhance the sound quality substantially. However, I'm happy with the sound I'm getting right now. It is definitely NOT "CD quality," and I wouldn't even mention it in the same breath as traditional analog sources as vinyl or RtR tape, but you know what?......it sounds damned good to me! It seems that the sound quality varies with the station. Jazz sounds very good, as does classical, while the sound quality of the 50's and 60's stations is pretty poor, about on a par with a 128 mp3. But the MUSIC is great, so what the hell, that's what it's all about anyway, right? I've also discovered that judicious use of an equalizer, with a slight boost in the midrange (500 hz-2000khz) really warms up the sound and gives it some body.....a definite improvement over the rather thin, unequalized sound.
As for headphones, I prefer the Sony MDR-CD1700 as they also impart a bit of warmth. Grados are just too revealing. Most of my listening, however, has been through speakers,

....... a pair of Klipsch Forte's driven by a vintage Harmon Kardon 430 Twin Powered Receiver.
Since I hooked XM up last week, I've listened to my other sources maybe 1 hour. There's just so much music and such a tremendous variety on XM, that I've been listening just about non-stop for over a week. I love it!

 

[gerG]

I can't listen to XM on any station for very long. The entire HF range seems to be some sort of time shifted replication of the midrange. After trying for almost 2 years I gave up. It is my personal belief that SBR is a farce, and they have pushed the bitrates to low, counting on the reconstruction to get them back to something listenable. Unfortunately my ears object. I mean that literally, my ears start ringing after 30 minutes on headphones and about an hour on speakers. I haven't heard the Polk yet. I was using a PCR with a digital output.

fwiw I listened mainly to the classical and latin jazz stations. I can tell from spectral response what bitrate they are using. I didn't see it go over 64 kbps.

I think that XM has a future just for the variety, but I won't be able to listen to it until I lose some more of my hf hearing.


gerG

 

[joelongwood]

Quote:

Originally Posted by gerG I think that XM has a future just for the variety, but I won't be able to listen to it until I lose some more of my hf hearing.

At 56, I guess I'm a prime candidate for XM.

 

[gerG]

Hi Joe! Sorry, I didn't mean that as an insult to your aural accuity. I don't understand why my ears react the way they do, but it is a real nuisance. I listen to AAC files encoded at 128 kbps all day long and don't have a problem. It seems to have something to do with that treble reconstruction algorithm that they are using. The goofy thing is that I keep paying the monthly fee, hoping that it will get better. Unfortunately my tolerance time seems to keep getting shorter. Maybe I just need to go shooting this weekend

gerG

 

[joelongwood]

No insult taken........I just accept it as fact.

To be honest, I can hear the digital artifacts, but I've been so focused on the music, that I guess I'm able to ignore the sound quality. I've been listening a lot to the 50's station, and, to me, it sounds just like I remember it, when I listened as a kid on my tubed Emerson AM radio, with the glow of the tubes in the back providing the only semblance of light in my darkened bedroom. Even the DJs sound as if they're broadcasting from the bottom of a barrel. I'm lovin' it!

 

[gerG]

lol, that would explain it then. I have a serious aversion to anything retro. My early audio years were spent trying to understand Dr Demento on a plastic AM radio. Thank god for orchestra rehersal. Hmmm... the latter is probably what messed up my hearing, now that I think about it. Well, that and the explosives.

btw, what ever became of the AKG K270s? I am still curious what the hell they did to those things. Maybe they need 3 drivers instead of just 2.


gerG

 

[joelongwood]

Quote:

Originally Posted by gerG lol, that would explain it then. I have a serious aversion to anything retro. My early audio years were spent trying to understand Dr Demento on a plastic AM radio. Thank god for orchestra rehersal. Hmmm... the latter is probably what messed up my hearing, now that I think about it. Well, that and the explosives. btw, what ever became of the AKG K270s? I am still curious what the hell they did to those things. Maybe they need 3 drivers instead of just 2.

The AKG 270s are now residing with my son in Boston........he liked the looks of them. I figured I wouldn't miss them (the 'phones, that is) too much........I was right. Maybe they did need a 3 way design, as you suggest.

Explosives? Damn, I spent my youth trying to avoid that kind of stuff at all costs. It was the LOUD rock concerts that probably did me in.

 

[kentamcolin]

That "lifetime" subscription is a scam, and the attorney general should get involved to end marketing like that. I had the same thing offered to me with "Tivo". I questioned the salesman about it and he said it was really "lifetime". When I found out after getting the unit home that lifetime is for the life of the Tivo receiver, but it only says that in the fine print, I returned it and bought another from a dealer who was at least honest about what was offered.

 

[erikzen]

I don't think the "lifetime" subscription is too bad as long as they are clear that it is for the radio. They should clearly state "Lifetime subscription for the life of your radio unit". They do it for automobile transmissions, why not radio subscriptions? But to make you think it is for your lifetime is a bit underhanded.

The consumer should always realize though that if something seems to good to be true, it is. Satellite radio would be giving away too much with that kind of deal. Imagine if we could have bought lifetime subscriptions to cable TV in the 70's? Where would the cable companies be now? I'm sure satellite radio broadcasters see themselves as being as big as cable in the next 20 years.