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goMac · May 17, 2007, 11:54 AM

I got a Accord EX V6 Coupe last week, and it came with XM radio on it. I'm not subscribed right now, I've just got the sampler. When I first looked at the car, I ignored the XM because at the dealer I listened to the talk radio stations, which were horrible sound quality. Now that I've gotten the car, I've been flipping through the stations and found that the music stations are pretty decent quality. I can't help to think they still sound a little flat compared to FM. Sure, FM has a static and XM doesn't, but the sound just sounds deeper on FM. And comparing the same song on XM and CD (burned from iTunes track), the CD definitely is higher quality.

What's everyone else's impressions of the sound quality on XM?

Oneota · May 17, 2007, 12:06 PM

I can't stand listening to the classical music stations on XM. The bitrate is just too low - everything sounds like it's under water.

That said, I don't mind channel 150 - spoken word content sounds okay at that quality level.

mac128k-1984 · May 17, 2007, 01:12 PM

My wife's got XM in her honda and she's very pleased with it. No complaints, well one complaint.
She was under the impression by subscribing she would not get any commercials. One of the stations she listens to does in fact have commercials

highstakes · May 17, 2007, 01:15 PM

Its very clear, there are no static or anything like that you hear in radio. Only reason I dont have XM now is because after a while you get bored of one channel, and you have a hard time finding a "good" channel.

wolfen · May 17, 2007, 03:00 PM

When satellite radio first came out it was touted as "CD-Quality" - and it was very high quality. Then to be more competitive, they created Sports channels, and Entertainment channels, and so on. The more commercial channels they added, the less bandwidth allocated to each channel. So the amount of data-per-channel has been split in half or worse since it first came out.

They realized that most people don't listen to the radio for the quality of sound, but for the variety of options.

Railroader · May 17, 2007, 03:16 PM

Originally Posted by wolfen

When satellite radio first came out it was touted as "CD-Quality" - and it was very high quality. Then to be more competitive, they created Sports channels, and Entertainment channels, and so on. The more commercial channels they added, the less bandwidth allocated to each channel. So the amount of data-per-channel has been split in half or worse since it first came out.

They realized that most people don't listen to the radio for the quality of sound, but for the variety of options.

This is one of the things that bugs me.

Luckily Apple will be increasing (at least offering the option) their bit rates.

Oneota · May 17, 2007, 03:30 PM

I wouldn't care so much about some channels. Sports, comedy, talk-radio...those can all be 32 kbit and no one would notice.

Some of the music channels really should be higher bitrate, though - classical music in particular tends to have more acoustic ranges than a lot of other genres, and you can really tell when it's being over-compressed.

imitchellg5 · May 17, 2007, 04:24 PM

The sound quality is okay for me. I like XM though.

Steve Bosell · May 17, 2007, 04:39 PM

Originally Posted by goMac

, FM has a static and XM doesn't, but the sound just sounds deeper on FM. And comparing the same song on XM and CD (burned from iTunes track), the CD definitely is higher quality.

FM may sound "deeper", but that is only because it is very compressed, to give one station the illusion of being louder than the other, in reality XM is much better quality than FM. The XM signal started out as 96 kbps back in the day, but they have gone to 64 kbps to fit more content. I like to listen to different types of music none of which is the homogenized garbage that you can find on any FM channel coast to coast, so for me it is great.

Mithras · May 17, 2007, 05:04 PM

What codec is XM compressed with? Something well-known, or a custom job? I imagine it's encrypted as well, of course.

Railroader · May 17, 2007, 07:30 PM

Originally Posted by Steve Bosell

FM may sound "deeper", but that is only because it is very compressed, to give one station the illusion of being louder than the other, in reality XM is much better quality than FM.

XM is NOT much better quality than FM. No way, no how.

A FM station doesn't "compress" its music as XM does, they do sometimes change the tempo and make the music faster. Whenever I detect this happening I call the station and complain. Though I rarely listen to the types of stations that speed up the music.

Originally Posted by Steve Bosell

The XM signal started out as 96 kbps back in the day, but they have gone to 64 kbps to fit more content.

So, you're saying that FM sounds worse than 64 kbps music?!?! You must be half deaf.

Railroader · May 17, 2007, 07:32 PM

Originally Posted by Mithras

What codec is XM compressed with? Something well-known, or a custom job? I imagine it's encrypted as well, of course.

From: http://www.answers.com/topic/xm-satellite-radio-hold

Audio channels on XM are digitally compressed using the aacPlus codec from Coding Technologies for most channels, and the AMBE codec from Digital Voice Systems for some voice channels.

goMac · May 17, 2007, 07:53 PM

Originally Posted by Railroader

So, you're saying that FM sounds worse than 64 kbps music?!?! You must be half deaf.

XM is much more muted than FM. The reason is FM is uncompressed. So the static is negligible, and the audio that comes through is not compressed like XM.

Railroader · May 17, 2007, 08:11 PM

Originally Posted by goMac

XM is much more muted than FM. The reason is FM is uncompressed. So the static is negligible, and the audio that comes through is not compressed like XM.

You should be addressing this to the other guy. He's the one who says XM sounds better than FM.

kikkoman · May 17, 2007, 08:45 PM

Originally Posted by goMac

XM is much more muted than FM. The reason is FM is uncompressed. So the static is negligible, and the audio that comes through is not compressed like XM.

I think he meant FM is compressed dynamically. It's done to overcome noise and the crappy speakers found in most cars. Dynamic compression tends to make things sound louder and many people will interpret that as sounding better.

analogika · May 17, 2007, 09:06 PM

Originally Posted by kikkoman

I think he meant FM is compressed dynamically. It's done to overcome noise and the crappy speakers found in most cars. Dynamic compression tends to make things sound louder and many people will interpret that as sounding better.

XM is sure to be dynamically compressed to hell as well - all radio is these days, as are all commercial CDs, because people have got so used to garbage that they perceive anything with an even *slightly* natural dynamic range as "too soft".

I'd suspect that the reason XM sounds thinner is because it's digitally compressed to **** in addition. 64kbps?

goMac · May 17, 2007, 09:10 PM

Originally Posted by Railroader

You should be addressing this to the other guy. He's the one who says XM sounds better than FM.

Oh sorry. Right you are. I thought you were saying 64 kps was worse than FM and I momentarily doubted you.

Railroader · May 17, 2007, 09:10 PM

Originally Posted by kikkoman

I think he meant FM is compressed dynamically. It's done to overcome noise and the crappy speakers found in most cars. Dynamic compression tends to make things sound louder and many people will interpret that as sounding better.

That makes more sense.

I think this wikipedia page does a good job of explaining FM compression.

But it is NOT that same thing as the compression codec that XM uses.

Railroader · May 17, 2007, 09:14 PM

Originally Posted by analogika

XM is sure to be dynamically compressed to hell as well - all radio is these days, as are all commercial CDs, because people have got so used to garbage that they perceive anything with an even *slightly* natural dynamic range as "too soft".

This is what kills me. And then people chose the fake surround sound options on their cheap stereos... I want to gouge my ears out sometimes.

Originally Posted by analogika

I'd suspect that the reason XM sounds thinner is because it's digitally compressed to **** in addition. 64kbps?

Exactly!

It wasn't always so bad, but it is much much worse than ever.

goMac · May 17, 2007, 09:28 PM

Does anyone know what the sound quality on HD Radio is? It's always sounded more attractive to me. There's no subscription fee, and you get the local channels you know and love. In addition, the Hondas let you hook in up to 3 external receivers, so I could install an HD radio receiver alongside the XM receiver.

Steve Bosell · May 17, 2007, 10:24 PM

Originally Posted by Railroader

XM is NOT much better quality than FM. No way, no how.

A FM station doesn't "compress" its music as XM does...

Great, so you realize now that FM is highly compressed. Yes 64 kbps digital sound is much better than the sampled and resampled 1940's FM style.

Railroader · May 17, 2007, 10:51 PM

Originally Posted by Steve Bosell

Great, so you realize now that FM is highly compressed. Yes 64 kbps digital sound is much better than the sampled and resampled 1940's FM style.

No, FM is dynamically range compressed [DRC]. It is NOT the same kind of bit rate compression as XM. And not all of FM is DRC.

And you must be half deaf to think that 64 kbps sounds better than DRC FM. XM is both DRC and bit rate compressed.

analogika · May 18, 2007, 04:21 AM

Originally Posted by Steve Bosell

Great, so you realize now that FM is highly compressed. Yes 64 kbps digital sound is much better than the sampled and resampled 1940's FM style.

Compare and contrast:

http://en.wikipedia.org/wiki/Audio_level_compression

http://en.wikipedia.org/wiki/Audio_data_compression

The first is an dynamic process that is (over)used on BOTH FM and XM (and on CDs, and DVDs, and pretty much all commercial audio). Employed to excess, it destroys dynamic range but mAKES EVERYTHING SOUND LOUD! THIS IS WHAT IS RESPONSIBLE FOR THE FACT THAT ON MODERN PRODUCTIONS AND IN THE RADIO, A SINGLE ACOUSTIC GUITAR WILL BE EXACTLY AS LOUD AS THE FULL BAND WITH STRINGS AND CHOIR THAT COMES IN AFTER THE SECOND BRIDGE. ITS OVERUSE IS THE EQUIVALENT OF TYPING EVERYTHING IN ALL CAPS; IT MAKES IT VERY DIFFICULT TO FOLLOW WHAT IS GOING ON BECAUSE EVERYTHING IS SHOUTING INTO YOUR EARS.

The second is what is measured in kilobits per second. It is a DIGITAL data reduction process that destroys what little "music" is left after overdone dynamic compression. This affects digital radio IN ADDITION to the brain-dead dynamic range compression and is responsible for the "artifacting" especially apparent on high frequencies - like on cymbals - at anything much below 192kbps.

Railroader · May 18, 2007, 07:46 AM

:d

-t

wolfen · May 18, 2007, 09:20 AM

In summary: We all miss analog.

analogika · May 18, 2007, 09:38 AM

That's entirely unrelated. Dynamic range compression of audio has been around since the 50s.

A better summary: People expect garbage, and others are willing to sell it to them.

wolfen · May 18, 2007, 09:57 AM

Originally Posted by analogika

That's entirely unrelated. Dynamic range compression of audio has been around since the 50s.

A better summary: People expect garbage, and others are willing to sell it to them.

I'm not arguing with your DRC knowledge, but I don't think digital v. analog is entirely unrelated to declines in sound quality. I know that The Wall vinyl sounds better than The Wall CD. The difference is clear to me. We can argue about why, but sampling is a compromise between what technology will allow, what publishers are willing to pay for, and what most people will accept. I don't like sampling. But since it's here, I want it to be doubled or tripled.

Steve Bosell · May 18, 2007, 10:15 AM

Originally Posted by Railroader

No, FM is dynamically range compressed [DRC]. It is NOT the same kind of bit rate compression as XM. And not all of FM is DRC.

And you must be half deaf to think that 64 kbps sounds better than DRC FM. XM is both DRC and bit rate compressed.

Any one that knows even a smidgen about sound quality realizes that when you are talking FM compression, it is not the same as bit rate sampling compression, or speeding up the tempo

. What the hell are you talking about? It does not take much of a trained ear to hear how awful FM sounds, XM is a step up, but not CD quality.

goMac · May 18, 2007, 10:17 AM

Originally Posted by Steve Bosell

Any one that knows even a smidgen about sound quality realizes that when you are talking FM compression, it is not the same as bit rate sampling compression, or speeding up the tempo

. What the hell are you talking about? It does not take much of a trained ear to hear how awful FM sounds, XM is a step up, but not CD quality.

Seems clear to me. FM uses dynamic level compression. XM users dynamic level compression and bitrate compression. So the XM feed is going to sound worse.

The FM feeds definitely sound better to me.

analogika · May 18, 2007, 10:32 AM

Originally Posted by wolfen

I'm not arguing with your DRC knowledge, but I don't think digital v. analog is entirely unrelated to declines in sound quality. I know that The Wall vinyl sounds better than The Wall CD. The difference is clear to me. We can argue about why, but sampling is a compromise between what technology will allow, what publishers are willing to pay for, and what most people will accept. I don't like sampling. But since it's here, I want it to be doubled or tripled.

Blame shitty transfers for the inferior quality of the original CD release.

Blame the obsession with "re-mastering" to make it sound like it was made in the 90s for the inferior quality of the later CD release.

Productions sound best in the medium they were created for. NOTHING can approach the musicality of a direct-from-horn phonograph recording, and any attempt to "clean up" the sound invariably removes the magic that makes those old recordings superior - in that one respect - to anything that came later.

Have a listen to Alan Parsons' "Eye In the Sky" album. That was a digital recording. He was pretty much the first one to use his ears and taste over tech specs.

Digital isn't per se worse than analog for *everything*, nor is analog per se better at *everything* - there are some things possible with one that aren't with the other, and digital makes a *lot* of things possible that weren't done before. They're just rarely done *well*.

Also note that analog audio engineering had been around for fifty years before the first digital recording equipment even hit the market. There is far less experience to draw from.

analogika · May 18, 2007, 10:37 AM

Originally Posted by Steve Bosell

Any one that knows even a smidgen about sound quality realizes that when you are talking FM compression, it is not the same as bit rate sampling compression, or speeding up the tempo

. What the hell are you talking about? It does not take much of a trained ear to hear how awful FM sounds, XM is a step up, but not CD quality.

I'm sorry, but everything you're confusing has already been clarified in this thread.

And if FM sounds awful, then blame the stations or your crap $5 radio, because FM *used to* be far superior to CD quality - until they started overcompressing and breaking it.

wolfen · May 18, 2007, 10:39 AM

analogika, I will accept your analysis. But logic, alone, dictates that higher sampling rate = more accurate reproduction. The only flaw I see in your otherwise flawless reasoning is this: sound is not digital. It doesn't matter what medium a sound was "created" for -- it's an analog wave that travels through the air, not a digital signal. You can digital-ize it and process it, or you can record it.The idea that nobody can tell the difference is silly.

Dakarʒ · May 18, 2007, 10:40 AM

XM would sound great on BOSE® speakers.

Steve Bosell · May 18, 2007, 10:48 AM

Originally Posted by goMac

Seems clear to me. FM uses dynamic level compression. XM users dynamic level compression and bitrate compression. So the XM feed is going to sound worse.

The FM feeds definitely sound better to me.

FM also uses bitrate compression, if you haven't noticed, all music is digital today, FM is purely analog. Like I said FM's signals is sampled and resampled again several times before it reaches you. Radio stations usually start with an MPG 1 sound file, but this digital signal is resampled several times as it goes through a chain of devices (with different sampling schemes) eventually becoming a very high power analog wave with not much bandwidth at all, so you can receive it 1940's style. Radio stations dynamically compress the signal to "make it sound better" but in terms of CD quality sound it is not even in the ball park. XM is transmitted to you digitally, and the music they send you is not at all or only a fraction as dynamically compressed as an FM station. XM is clearly a much more dynamic, higher quality sound, it upset me when they went from 96 to 64 kbps, but I am to the point where I can not even listen to FM.

goMac · May 18, 2007, 10:53 AM

Originally Posted by Steve Bosell

FM also uses bitrate compression, if you haven't noticed, all music is digital today FM is purely Analog.

All music, whether on FM or on your computer, is converted to analog. When you plug in headphones into your computer, the music is digital but the output is analog. Unless you use optical audio, you're listening to your music over analog.

And analog isn't compressed by bitrate for transmission. That's what makes analog analog and digital digital. If an analog signal was digitally compressed, it wouldn't be analog, now would it?

Steve Bosell · May 18, 2007, 10:57 AM

Originally Posted by goMac

All music, whether on FM or on your computer, is converted to analog. When you plug in headphones into your computer, the music is digital but the output is analog. Unless you use optical audio, you're listening to your music over analog.

And analog isn't compressed by bitrate for transmission. That's what makes analog analog and digital digital. If an analog signal was digitally compressed, it wouldn't be analog, now would it?

Did you even read my post?

goMac · May 18, 2007, 11:07 AM

Originally Posted by Steve Bosell

Did you even read my post?

Yes, and I think you're completely overestimating how much sound quality is lost in a digital to analog conversion. Given that most people today who play MP3's on their iPods don't notice the sound quality loss in a digital to analog conversion, I really doubt it's a problem with FM. The only real problem with FM is the static when the radio looses part of the signal.

Steve Bosell · May 18, 2007, 11:22 AM

Originally Posted by goMac

Yes, and I think you're completely overestimating how much sound quality is lost in a digital to analog conversion. Given that most people today who play MP3's on their iPods don't notice the sound quality loss in a digital to analog conversion, I really doubt it's a problem with FM. The only real problem with FM is the static when the radio looses part of the signal.

It is not one digital to analog conversion, it is several analog to digital, digital to analog, and digital to digital conversions that the FM signal goes through before it reaches you. The FM signal it tortured to hell, and it shows, you will notice 10X more digital artifacts on an FM station than XM, FM sounds like they send the signal through a BOSS Metal Zone guitar pedal. But I guess it sounds good to people who have the subwoofer turned up to 10 on their Bose home entertainment system.

goMac · May 18, 2007, 12:05 PM

Originally Posted by Steve Bosell

It is not one digital to analog conversion, it is several analog to digital, digital to analog, and digital to digital conversions that the FM signal goes through before it reaches you. The FM signal it tortured to hell, and it shows, you will notice 10X more digital artifacts on an FM station than XM, FM sounds like they send the signal through a BOSS Metal Zone guitar pedal. But I guess it sounds good to people who have the subwoofer turned up to 10 on their Bose home entertainment system.

Ok. Sooo...

FM:
Digital->Analog->Your Car->Speakers

XM:
Digital->Your Car->Analog->Speakers

Advantage is...? Digital to analog conversions aren't nearly as costly as you think. The biggest problem is the dynamic range compression... but after that's done once, it won't be an issue again.

And how exactly does a digital to digital conversion work?

awaspaas · May 18, 2007, 12:24 PM

Originally Posted by goMac

All music, whether on FM or on your computer, is converted to analog. When you plug in headphones into your computer, the music is digital but the output is analog. Unless you use optical audio, you're listening to your music over analog.

Luckily I've had an SPDIF audio port implanted in the side of my head so I can listen to digital audio directly.

goMac · May 18, 2007, 12:27 PM

Originally Posted by awaspaas

Luckily I've had an SPDIF audio port implanted in the side of my head so I can listen to digital audio directly.

Hey, that's a good point. Even optical audio is converted to analog when it's played over your speakers.

Railroader · May 18, 2007, 01:36 PM

Originally Posted by Steve Bosell

Any one that knows even a smidgen about sound quality realizes that when you are talking FM compression, it is not the same as bit rate sampling compression, or speeding up the tempo

. What the hell are you talking about? It does not take much of a trained ear to hear how awful FM sounds, XM is a step up, but not CD quality.

You don't know that some stations speed up music to give it more "life" and to add more time for advertising?

You better retrain your ear. Especially if you think music encoded at 64 kbps sounds better than FM.

Dakarʒ · May 18, 2007, 01:37 PM

Originally Posted by Railroader

You don't know that some stations speed up music to give it more "life" and to add more time for advertising?

Oh christ. This could explain why Wonderwall hasn't sounded right to this day.

goMac · May 18, 2007, 01:45 PM

Originally Posted by Railroader

You don't know that some stations speed up music to give it more "life" and to add more time for advertising?

I've noticed this just in listening to music. Pisses me off every time they do that. That, and just plain dropping parts of songs.

Railroader · May 18, 2007, 01:56 PM

Originally Posted by Dakarʒ

Oh christ. This could explain why Wonderwall hasn't sounded right to this day.

You should have worked in a record store and had to deal with customers who want the "radio version". Ugh.

Railroader · May 18, 2007, 01:56 PM

Originally Posted by goMac

I've noticed this just in listening to music. Pisses me off every time they do that. That, and just plain dropping parts of songs.

There are two stations near me that do this. I wish my radio had a "skip channel" feature like my TV has.

Dakarʒ · May 18, 2007, 02:20 PM

Originally Posted by Railroader

You should have worked in a record store and had to deal with customers who want the "radio version". Ugh.

Yeah, I imagine even the single is normal speed.

Seriously though, it used to bother the shít out of me that when the song came on iTunes and I was always humming, singing or keeping beat way faster than it. I could never figure out why I was under the impression it should go faster. But back in '95 when it came out the radio played the hell out of it, and since I drove a ton then, that version must have been ingrained in my mind.

As you can see this is somewhat of a revelation for me.

Oneota · May 18, 2007, 02:32 PM

Meh. I just keep my radio on NPR. They don't screw up their music anywhere near as much as the commercial stations do.

I ♥ NPR.

Dakarʒ · May 18, 2007, 02:34 PM

I feel like you just placed a powder keg in the room.

analogika · May 18, 2007, 02:40 PM

Originally Posted by wolfen

analogika, I will accept your analysis. But logic, alone, dictates that higher sampling rate = more accurate reproduction. The only flaw I see in your otherwise flawless reasoning is this: sound is not digital. It doesn't matter what medium a sound was "created" for -- it's an analog wave that travels through the air, not a digital signal. You can digital-ize it and process it, or you can record it.The idea that nobody can tell the difference is silly.

It's what happens to the signal BEFORE it hits your speakers that makes the difference. (Duh.

)

If you're recording/mastering for a 180g vinyl jazz album, you will use completely different technology and techniques, from the very first step - the studio acoustics - to the very last - mastering - from when you're recording a track intended to be included on a pop compilation album (where primary intent is to blow everybody else on the album away).

Depending upon what you're doing, different combinations of analog and digital stages/processes/equipment deliver the most effective/best-sounding results.

And there is an awful lot of stuff that's digital-based that would simply be outright impossible with analog means.

(There is also an awful lot of stuff that's digital-based that would have been much BETTER with analog means, but it would have meant artists who could actually play a whole lot better...)

And actually, a higher sampling rate is FAR less important than higher bits-per-sample, because it's the dynamic range, not the frequency range, that primarily affects sound quality. 24 bits at 44.1 kHz actually sound much better than 16 bits at 96 kHz.

Of course, dynamically compress that at 40:1 and run it through two stereo "enhancers" and another vitalizer in series before sending it across the ether (this is normal procedure at radio stations), and it really doesn't matter **** what the original signal was.