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JBL LSR305 Hiss question (again)

Discussion in 'Computer Audio' started by illram, Dec 10, 2017.
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  1. illram
    Last thread on this was 2 years old so figured this could get it's own new thread. Simple question: My LSR305's have no hiss when plugged into my phone (or not plugged into an audio source), but have a very noticeable hiss when plugged into a USB DAC (run either directly or via powered hub) or the headphone/line-out out on my monitor. What does that indicate?

    I am guessing this is a power issue given they work off my phone and are silent? If this were a USB issue, I would assume there would be no hiss on the line-out of my monitor. I was looking into the various powered USB de-crappifiers but I am unsure if that will do anything, also since a powered USB hub does nothing either, and I have zero problems with other USB DACs. Isolating the speakers on their own outlet is not an option here. What's my issue here?

    Thanks!
     
  2. davidland
    I planned to buy one JBL LSR305's, your experience makes me a little concerned...
     
  3. illram
    It's a known issue with these speakers out of certain equipment. Using them as bookshelf speakers right on my computer desk can't work with this hiss. I'm going to try using an optical DAC and see if that works.
     
  4. Music Alchemist
    How loud is the hiss?

    When I owned the LSR305s, the tweeters made a soft hiss, but they're supposed to. Even my passive speakers have tweeter hiss. (With some speakers, you may not be able to hear it unless you put your ears right next to them.)

    I also had ground loop noise (much louder and more annoying) coming from my laptop power supply, so that's not the speakers' fault. This can be fixed with a ground loop isolator or electronics that input/output optical TOSLINK, which electrically isolates the DAC. (You can also use a cheater plug, but this is potentially unsafe.)
     
    Last edited: Dec 13, 2017
  5. illram
    Louder than your normal hiss. I cannot listen to anything at a low volume on the speakers.

    Like you said I suspect it is a power related issue since I can eliminate the hiss when using them with my phone. Hopefully when I can get around to trying out an optical DAC instead I will figure out this issue.
     
    Last edited: Dec 13, 2017
  6. Music Alchemist
    The normal hiss from the LSR305 is quiet enough that you'd have to be close to them with no music playing to hear it.

    I suspect it's ground loop noise, then, so any of the solutions above should fix it.

    If your computer is a laptop, unplug the power cable. If the noise stops, you know it's a ground loop.
     
    Last edited: Dec 13, 2017
    illram likes this.
  7. PurpleAngel Contributor
    Maybe you have a ground loop issue?
    Try replacing the USB DAC with an optical DAC
    https://hifimediy.com/DACs/ready-made-dacs/SPDIF-9018-DAC?sort=p.price&order=ASC
    Get a separate surge protector for plugging the LSR305 into.
     
  8. Nuke142
    I have same problem with my Fiio Ex1 iem.
    100% silent when power is unplugged but some noise when powered up.
    No matter build-in 3.5jack in to laptop or external usb sound card (creative).
    When i touch 3.5 female jack with 3.5 male i hear a noise. Noise dissappeared if i touch jack with my fingers.
    Want to buy 3.5 ground loop isolator but i can see so much reviews that is so bad for sound quality..
    Also i want to buy lsr305 too.
     
    Last edited: Dec 16, 2017
  9. illram
    I figured this out, hope this helps someone else: I eliminated the hiss using 3 prong to 2 prong adapters. Totally silent out of my DAC and/or my Magni 3.

    I have no idea why this is, but, there you have it.
     
  10. Music Alchemist
    Yes, that's a cheater plug. It's what I used:

     
  11. mindbomb
    Two things you can do are either use toslink input to the dac, or balanced output from the dac.
     
  12. Sterling2
    Just some anecdotal input, I purchased a Roxio Kit to digitize my LP's, The kit included an ADC. When the ADC was connected to my computer's usb port I noticed something was not right, it was noisy. It turned out that there were two issues, 1. the RCA cables which came with the kit were defective and when replaced the noise subsided a little bit, 2. the ADC was defective and when replaced with a Creative Sound Blaster X-FI HD the noise disappeared. The lesson is noise can come from pretty much anywhere; but, to get rid of it you should begin by looking at ALL things in the system which were changed to bring about the noise. In my case, after all was said and done, I realized I could have ripped my vinyl without any need for a "kit" to do it. I only needed software. BTW, the JBL speakers are awesome and when installed properly will be quiet as a mouse.
     
  13. BrightCandle
    Even then its unusual for a ADC to be just flat defective in this way. The most likely cause is probably its power source and its failing to deal with the noise in the power coming to it, which in turn could be anything on that loop or potentially in the house at all. Sometimes its very very difficult to track down the cause. USB is notoriously noisy coming out of motherboards but it is by no means a universal issue. Plenty of AC to DC converters also have significant noise and then sometimes its just a simple failure. They are always hard to track down even with older gear when it suddenly happens.
     
  14. Sterling2
    The defective ADC was usb powered.
     
  15. Music Alchemist
    It still makes a soft hissing sound from the tweeters no matter what, though. Even passive speakers can do that.
     
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