Volume difference between radio and Sirius XM?

Discussion in 'Gen 3 Prius Audio and Electronics' started by DrPepperholik, May 5, 2014.

  1. DrPepperholik

    DrPepperholik Active Member

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    I just got my 2014 Prius Three and it doesn't seem to have a premium sound system on it. I have 90 days of free Sirius XM radio and I have noticed a marked difference between volume of the Sirius radio and regular radio. Is this related to the lack of premium sound system? I came from a Mustang with a premium Shaker system so this sounds funny to have to turn the volume up to the 30's to get the same quality as the Sirius radio. The Mustang had a difference but not as much as the Prius.
     
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  2. bisco

    bisco cookie crumbler

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    i don't know if that's the reason, but mine is the same way. also, big difference between cd, usb and radio.
     
  3. lumpy95

    lumpy95 Member

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    Ditto on what bisco said, it's the same with my 2013 model three.
     
  4. 70AARCUDA

    70AARCUDA Active Member

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    Much of the volume difference is due to MP3-like "compression" that's used on CD's and XM (digital) transmissions, but is NOT used on normal AM/FM transmissions.
     
  5. DrPepperholik

    DrPepperholik Active Member

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    So it's not the quality of the system or anything then? It's a shock when I go from XM to FM.
     
  6. tach18k

    tach18k Member

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    XM audio is modulated a bit more than normal FM, due to many factors. thus the way the radio gets it, is the way it comes in. Kind of like commercials on Cable TV system, they are over modulated so they disrupt your sleeping. the amp in the head unit, amps up the signal it gets equally, so if it comes in at 3 it amps that 15 times, so 45, if it comes in at 5 it amps it to 75. thus louder.
     
  7. acceleraptor

    acceleraptor Member

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    I only recently noticed this problem (which I don't quite remember when I was first driving, strangely enough), but it seems like AM is mostly the really low volume one. I'll have to test this in a bit to be more sure..
     
  8. DrPepperholik

    DrPepperholik Active Member

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    Suddenly the name of AM (amplitude modulation) and FM (frequency modulation) make sense! Off to google to understand what modulation means/does and how that effects the sound quality.

    Commercials do that on purpose?! That's annoying. I think most people mute the tv or turn the volume down during commercials.
     
  9. acceleraptor

    acceleraptor Member

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    Modulation refers to altering a signal (the content, e.g. voltage of the audio signal you're listening to) by mathematically combining it onto another signal (the carrier, e.g. a high-frequency signal that will sustain being transmitted over radio waves long enough distances for receivers to reliably receive that signal). The original content then gets "demodulated" off the known carrier.

    This typically involves multiplying|convolving one signal onto the other. IIR, FM was found to be a better modulation method for maintaining the fidelity of audio frequency ranges commonly used in human singing and music.

    Not sure the difference between AM and FM really have much to do with the difference in handling volume gain anymore. At least, this should be a long solved problem. My suspicion would be that any differences are due to something else, like just lack of proper engineering design.
     
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  10. Horsefeathers

    Horsefeathers Member

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    So would the same things apply to explain the difference between the music played through my iPhone vs. the (plain old FM) radio? I checked to make sure the volume on the phone was set to maximum. When I used to play music through my phone on my old car, it was plugged in to the aux port, but the volume seemed consistent whether radio or phone. Now that I'm bluetoothing (and my first experience ever doing that), the music on my phone plays way lower than the radio. It's adequate and loud enough when turned up, but I did wonder why it was so much lower, and it is alarming to switch between them if I don't remember to turn down the car stereo first before switching back to the radio.
     
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  11. DrPepperholik

    DrPepperholik Active Member

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    That's interesting. Now I see why in school they wanted us to know calculus for the computer science program. Suddenly I wish I was more adept at math like my dad, in his education and career he had to do complex math problems that just looking at them make me go cross eyed, but that gene skipped my sister and me.
     
  12. DrPepperholik

    DrPepperholik Active Member

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    I'm beginning to think you're stalking me. ;)

    Based on my understanding so far (again, the bulb just went on for me not long ago but I do grasp the concept now) is that would explain the difference in quality. Bluetooth is a wireless connection that transmits data over radio waves so yes, the volume difference between FM and Bluetooth would due to the modulation of the different transmission types (FM or whatever Bluetooth uses) just like my experience with FM and XM.

    I must research this further, my interest is piqued.
     
  13. Horsefeathers

    Horsefeathers Member

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    Ha, it kind of looks like it. I promise I'm not!
     
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  14. acceleraptor

    acceleraptor Member

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    They'd added an intro signal processing course requirement by the time I went back to complete my EECS degree. For better or worse, I stuck with focusing all on CS so only ever learned the basic theory (math) behind signals. It has turned out to have unexpected benefits in for potential exploration of interdisciplinary pursuits: image processing, market analysis, information processing.

    Music from our iPhones is typically .mp3, a digitally stored and compressed format that's decompressed on-the-fly and played back. AM/FM radio is still an analog transmission path, as far as I'm aware (there're actually places along the data path where it goes through both, but when we think of one as being "digital" vs "analog" it's in a critical portion where information loss is most likely to occur like in transmission|reconstruction.

    My understanding though is that perceptible volume differences are issues of simply not accounting for automatic volume gain adjustments at a higher level of design, or, more likely in my mind, accounting for it, but it not being robust. An example of this latter would be if some manner of "resetting" the entire audio source appliance clears the problem up and this behavior occurs due to some unanticipated sequence of events we've happen to hit upon. I wonder how common this issue has been reported in the Audio forum..
     
  15. DrPepperholik

    DrPepperholik Active Member

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    Now that I understand it better I could see the use in signal processing for my field. There are tons of applications that need to transmit some data of some sort to another device and having at least a basic understanding of that would be nice. After I got laid off last summer I saw a few jobs that required some level of knowledge in signal processing.

    I think you're right about the volume differences not being accounted for at some point along the design because in my Mustang there was a noticeable difference but it wasn't bad enough to have to turn the volume way up. However, in the Prius it is a huge volume difference between the two.
     
  16. acceleraptor

    acceleraptor Member

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    I'm pretty sure I remember AM not suffering this when I drove it off the lot. I actually thought it was just the particular local Chinese AM station for my mom to listen to. Really gotta test the other AM stations now to confirm this (the current state, at least). For the record, CD and BTSA all work with volumes in the 20s. PiP base audio system here. Hmm.. really damn odd..

    Yeah, it's got relevance to data|info storage as well. Compression techniques too. Shannon(-Nyquist-FamousGuy3-FamousGuy4) information theory all says stuff about what "information" is, what peak theoretical limits to how much they can be compressed is an' all. Also shows up in networking topics, comm of any sort, obviously..
     
  17. DrPepperholik

    DrPepperholik Active Member

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    Local Chinese station eh? Pretty cool. Our AM stuff is talk radio and bluegrass music. I'll have to plug in my old iPod and see how it goes. I don't use my phone for music and I only used my iPod in my 2000 Contour which I installed a Pioneer radio in that had a cord going to my glove box for the iPod which charged it while it played from it, now that didn't have any difference in volume.
     
  18. acceleraptor

    acceleraptor Member

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    Yeah, the Chinese station is a mix of talk and music (and also likely due to a combination of cost-cutting and music stations having more revenue from ads for FM bands--there're some local Latin stations also appearing on AM more). The bluetooth source audio seems pretty decent but I don't really carry music on my iPhone, an' haven't really looked into the EnTune app the car keeps goin' on about having.
     
  19. DrPepperholik

    DrPepperholik Active Member

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    I didn't know I had music on my phone until I got my car and the saleswoman connected the Bluetooth for me then we heard music from my phone. It wasn't bad though but I still won't listen to music that way.

    I discovered something yesterday after unplugging my phone from the car that the warning the phone says when you connect it to a non-apple cord is there for a reason. I have the connectivity package with my car (I tried to get it removed but they wouldn't budge, it's the stupid cords for Android phones, iPhone and iPhone 5) and I couldn't unlock my phone, the lock screen image was my wallpaper image and it was difficult to turn off.
     
  20. Alan Claver

    Alan Claver Junior Member

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    Each source has it's own volume level memory. Not sure if you've noticed that. Probably not what you mean but thought I'd mention it. Indeed I have my XM volume level on 18 or so and my Bluetooth streaming/iPod source volume level on 25-30.
     
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