Is my HK 325 blown already? Inputting from laptop...

Discussion in 'AV Receivers' started by Simon Young, Oct 13, 2003.

  1. Simon Young

    Simon Young Stunt Coordinator

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    I got my Harman Kardon 4550 set up on Friday night, and tried a few movie soundtracks on it as well as a CD or two. Sounded great. However, I've now got my PowerBook plugged into it via the Video Aux 4 input on the front, and I'm using iTunes to listen to music until I get my new iPod to play MP3s.

    That's where the problem started. The music seems to lack weight, with mid-tones becoming weak and the trebles going to the harsh side of bright. At first, at low levels I didn't notice. But when I turned the amp up a bit, the music just didn't involve me at all. So I went to my PowerBook and plugged in headphones instead - it sounded similar, but...well...better. I didn't know what to make of this. So I tried a few movies out, and they all sounded fine. Maybe not as impressive as I was expecting, but fine all the same. My one CD (!) sounded OK too, although I had, by this point, become paranoid that the amp was broken, so I began to analyse every tiny imperfection in the recording. Was the brightness of that guitar the recording's fault or the amp's?

    The one thing that occured to me was, that the PowerBook must amplify the sound internally before pumping it out of the headphone socket. So, by plugging it into the amp, I'm essentially amplifying a pre-amplifed source. Could this effect the sound adversely, and account for the degredation I've been hearing? How do headphones differ from speakers in that regard?

    Finally, how likely is it that I've damaged the amp? I haven't played it excessively loud for any extended period. It's all set up correctly and wired correctly. On the other hand, my speakers could have blown, but I wouldn't know how to diagnose this. Basically, what are the tell-tale signs that something, be it an amp, or some speakers, has been damaged?

    Sorry for the unfocussed rant, but it's stressing me out!
     
  2. Jake K

    Jake K Stunt Coordinator

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    Using the Headphone output is a terrible way to connect a laptop to a stereo. The amp is most likely just fine.
     
  3. agendrano

    agendrano Extra

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    Just curious, does iTune download the MP3 from the internet or the MP3 files are stored in your hard disk?

    MP3 in my experience really does not have the quality compared to Vinyls/CD's/DVD Audio/SACD. I gave up playing MP3s on my system.

    Your HK 4550 most likely is fine, it might just be amplifying the imperfection of the MP3 source.
     
  4. ColinM

    ColinM Cinematographer

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    What would happen if someone overdrove the inputs?
     
  5. Simon Young

    Simon Young Stunt Coordinator

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    Thanks for the replies! I'm not actually playing MP3s, but AAC files (essentially MPEG-4, a format which iTunes uses exclusively for audio). Encoded at 192kbps, the quality is actually extremely good and near indistinguishable from the source. All of the tracks are taken from my own CD collection, none are downloaded.

    I thought that the headphone socket would be a bad way to go. From now on, I'll just sit tight until my iPod gets here (it has a line out).

    Other than that I don't know what else to try. As I said, I've got a little paranoid about the amp now, and am scrutinising everything. What doesn't help is the fact that I've just moved from home (small, well furnished bedroom) into a flat at college (larger bedroom, higher ceiling and with less furnishings). As I'm very used to how my old amp sounded in my bedroom, I'm perhaps blaming the accoustics of this particular room on my amp. Can anyone suggest ways to warm up the sound in the room? Cloth hangings on the walls, perhaps?
     
  6. Simon Young

    Simon Young Stunt Coordinator

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    OK, I'm now going nuts. I got my iPod yesterday, and bought a pair of high-quality interconnects to go from the line-out to the amp. Wired it in, checked all of the other connections (nothing wrong there), and hit play. Again, the same limp sound I had experienced before. I can't explain it really - it sounds as though the treble and bass are both fine, if a tad over exaggerated, but the mid-range is really subdued and harsh. I know that my Mission speakers are fairly bright, but I've always got a nice sound from them. Now, either my new iPod sounds rubbish (which I find hard to believe as it gives pleasing performance through headphones, and the MP3s never sounded like this before), or my speakers have blown, or the amp has some sort of internal fault that distorts the speaker output. Or my ears have suddenly got worse.

    What course of action do people recommend? Take it back to the store where I bought it, or call Harman Kardon directly? Are there any tests I should perform first? Ways of testing the quality of my speakers? Things I might try before packaging the amp up and sending it on its merry way?

    Please someone, I need some advice!
     
  7. ColinM

    ColinM Cinematographer

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    Are these the only sources you have? As in laptop and iPod?

    No CD / DVD player?
     
  8. Simon Young

    Simon Young Stunt Coordinator

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    Of course, I have a DVD/CD player as well. It's just that, having transferred all of my music to my laptop over the summer, I left my CD collection at home and just took the laptop to University. Now the music is all transferred to the iPod, so I'll be using that and its line-out for music duties. I'm assuming that a line-out is an acceptable method of delivery?

    As for the quality of the iPod...well, the only CD I have at the moment is the Kill Bill soundtrack, so I stuck that on the iPod then did an A/B test. Both sounded very similar, if not identical to my ear. Then again, I suspect the problem is be the amp or speakers, as the degredation in sound has occured in movies as well.
     
  9. ColinM

    ColinM Cinematographer

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    I guess you should bring it in to the retailer (Mail order?) and do a comparison...I hope it's going to work out for you, what a bummer!

    Good Luck -

    Or bring the Ipod in somewhere and demo it on another unit, that'd be interesting...
     

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