Page 1 of 2 12 LastLast
Results 1 to 16 of 17

Thread: Problems Connecting Laptop To PA / Amp

  1. #1
    Member
    Join Date
    Apr 2005
    Posts
    81
    Thanks
    0
    Thanked
    0 times in 0 posts

    Problems Connecting Laptop To PA / Amp

    When connecting my laptop to various guitar amps and PA's I've had the same problem each time, I get feedback which seems to be the equivalent of PC background noise. It changes when you open folders and carry out tasks on the laptop...it's as if you can hear the laptop think....I've had this problem when using the onboard laptop chipset, an Audigy2 PCMCIA and an M-Audio FireWire solo....do I need to connect the laptop to a pre-amp or something prior to connecting to any form of amplified speakers or PA? Or is it something to do with cables? Or perhaps I need a very specific type of amplifier for the laptop?

    This problem does not occur on typical PC speakers (GigaWorks S750, headphones etc..) so I know the system is working fine...it's just a case of me doing something wrong or missing a required piece of hardware.

    Any help is greatly appreciated

  2. #2
    Admin team peterb's Avatar
    Join Date
    Aug 2005
    Location
    Southampton
    Posts
    19,192
    Thanks
    2,804
    Thanked
    3,347 times in 2,649 posts
    • peterb's system
      • Motherboard:
      • Nascom 2
      • CPU:
      • Z80B
      • Memory:
      • 48K 8 bit memory on separate card
      • Storage:
      • Audio cassette tape - home built 5.25" floppy drive
      • Graphics card(s):
      • text output (composite video)
      • PSU:
      • Home built
      • Case:
      • Home built
      • Operating System:
      • Nas-sys
      • Monitor(s):
      • 12" monocrome composite video input
      • Internet:
      • No networking capability on this machine
    You are picking up electrical noise from the internals of the PC. You don't hear it on typical PC speakers because they are pretty low quality and pretty insensitive, but you are feeding it into a sensitive amplifier. You aren't feeding it into a guitar pick up input are you? If you are, then it is no wonder you are getting problems - the impedance matching will be wrong for a start, and it will be FAR too sensitive. You should be using an 'ordinary' auxiliary input on the guitar amp, or feeding it via a mixing desk with an aux input.
    (\__/)
    (='.'=)
    (")_(")

    Been helped or just 'Like' a post? Use the Thanks button!
    My broadband speed - 750 Meganibbles/minute

  3. #3
    Member
    Join Date
    Apr 2005
    Posts
    81
    Thanks
    0
    Thanked
    0 times in 0 posts
    Cheers, I've managed to resolve the issue by running the audio signal through a numark mixer before it hits the Amplifier, there's no excess background noise now

    thanks again

  4. #4
    Admin team peterb's Avatar
    Join Date
    Aug 2005
    Location
    Southampton
    Posts
    19,192
    Thanks
    2,804
    Thanked
    3,347 times in 2,649 posts
    • peterb's system
      • Motherboard:
      • Nascom 2
      • CPU:
      • Z80B
      • Memory:
      • 48K 8 bit memory on separate card
      • Storage:
      • Audio cassette tape - home built 5.25" floppy drive
      • Graphics card(s):
      • text output (composite video)
      • PSU:
      • Home built
      • Case:
      • Home built
      • Operating System:
      • Nas-sys
      • Monitor(s):
      • 12" monocrome composite video input
      • Internet:
      • No networking capability on this machine
    Excellent!

    ("A satisfied customer - we should have him stuffed" ... Basil Fawlty)
    (\__/)
    (='.'=)
    (")_(")

    Been helped or just 'Like' a post? Use the Thanks button!
    My broadband speed - 750 Meganibbles/minute

  5. #5
    Registered User
    Join Date
    Apr 2008
    Posts
    2
    Thanks
    0
    Thanked
    0 times in 0 posts

    Re: Problems Connecting Laptop To PA / Amp

    Greetings
    I seem to have a simmilar problem connecting my dell latt and sony viao to a PA. Howling noise of hard disk and other electrical noise goes comes trough as soon as the jack is pluged in the laptop. The noise reduces in loudness when power cable is plugged out the laptop and it is running on batteries but the sound stays bad. No problem with a pc or with any other devices. Asked in sony shop and have been adviced to buy external soundcard. The external sound card is plugged in to the usb drive but this does not remove or reduce the noise at all. As soon as the jack is plugged into the external sound card the noise reappears. I have not tried to connect the external SC though optical connection to the PA because my PA has no opttical input. I was also suggested to buy a special extension lead that is supposed to 'ground' better but have not yet tried it. If any of ye have an Idea or have the same experience (specially DJ's) I'd be grateful if ye would share this.

    All blessings,

    Rastinny

  6. #6
    Admin team peterb's Avatar
    Join Date
    Aug 2005
    Location
    Southampton
    Posts
    19,192
    Thanks
    2,804
    Thanked
    3,347 times in 2,649 posts
    • peterb's system
      • Motherboard:
      • Nascom 2
      • CPU:
      • Z80B
      • Memory:
      • 48K 8 bit memory on separate card
      • Storage:
      • Audio cassette tape - home built 5.25" floppy drive
      • Graphics card(s):
      • text output (composite video)
      • PSU:
      • Home built
      • Case:
      • Home built
      • Operating System:
      • Nas-sys
      • Monitor(s):
      • 12" monocrome composite video input
      • Internet:
      • No networking capability on this machine

    Re: Problems Connecting Laptop To PA / Amp

    It is interference generated by the laptop internals (anything ifrom the screen inverter - does the noise reduce if the screen blanks? - to other internal inverters, timer chips etc. There is noise being generated by the external PSU, as the noiser reduces when that is disconnected.

    One way to tackle it would be with a special audio transformer that would electrically isolate the laptop output from the PA input - but they aren't cheap., and may not cure the problem if it is radiated interference. (One way to determine that is if the lead is unplugged from the laptop, but held near it - but that isn't conclusive on its own).

    The PA probably has a balanced input, compputer do not have balanv]ced output. Some form of audio balun might also work (cheaper than a high quality audio transformer. You also need to look at the impedance of the PA input. Generally these are low, but if you are using a high impedance input, that can cause problems.

    As I said in an earlier post on this revived thread, these problems can be very difficult to track down and fix.
    (\__/)
    (='.'=)
    (")_(")

    Been helped or just 'Like' a post? Use the Thanks button!
    My broadband speed - 750 Meganibbles/minute

  7. #7
    Registered User
    Join Date
    Apr 2008
    Posts
    2
    Thanks
    0
    Thanked
    0 times in 0 posts

    Re: Problems Connecting Laptop To PA / Amp

    Thank you very much for your response! I agree the problem is very difficult to source and to solve. Last saturday I went out and bought a €65 extension lead supposed to 'ground' better and eliminate the noise but this has also failed to produce an improvement. The noise is relentless and I'm now out of idea's. The last thing I may try is to buy a new power adapter cable. This will put me back about €150 so I'd rather not but...
    Any other suggestions are still welcome

    Question? Is there a certain measurable range of noise which an audio jack from a laptop is expected to produce? How do you measure this, what is the unit of measurement and should this be specified in the computers technical specifications.
    Could it be that the amp and the speakers I use are simply too sensitive and are made to process audio of a different input range?

    How expensive is the transformer you suggest and how does it actually work.

    The audio input at my mixer is analog (red and white).

    Thank you for responding!

    All Blessings!

  8. #8
    Admin team peterb's Avatar
    Join Date
    Aug 2005
    Location
    Southampton
    Posts
    19,192
    Thanks
    2,804
    Thanked
    3,347 times in 2,649 posts
    • peterb's system
      • Motherboard:
      • Nascom 2
      • CPU:
      • Z80B
      • Memory:
      • 48K 8 bit memory on separate card
      • Storage:
      • Audio cassette tape - home built 5.25" floppy drive
      • Graphics card(s):
      • text output (composite video)
      • PSU:
      • Home built
      • Case:
      • Home built
      • Operating System:
      • Nas-sys
      • Monitor(s):
      • 12" monocrome composite video input
      • Internet:
      • No networking capability on this machine

    Re: Problems Connecting Laptop To PA / Amp

    There is no spec (afaik) that states how much noise an audio output should produce. Laptops are particularly bad - plastic cases which reduce shielding, lots of high frequency components in a small space, onborad soundcards - again with poor shielding. Sadly it is difficult to tell waht make or model will be troublesome or not without trying. (I have a panasonic that is pretty good - just pot luck)

    It could be that you are overdriving the amplifier, particularly if the sound is distorted. You need a line output (not often found on laptops) and a line in at the mixer. Worst combination is headphone out, microphone in on the mixer. If you have to use a headphone output, the volume on the laptop may need to be reduced.

    An audio transformer (you need one per channel if you using stereo) isolates the signal earth from the amplifier signal earth, so it can reduce the risk of earth loops that can be a source of interference (series mode interference) Using balanced lines (which it seems your mixer doesn't have) reduces common mode interference.

    as for cost, anything from a couple of punds upwards - professional quality (very flat frequency response etc) are very expensive.

    For a selection, look here

    Maplin > audio

    Note that these are components and will need mounting on some sort of circuit oard, and enclosing in a case. You would need one (per channel) of the more expensive ones (about £7.00 or £10,00). The cheap ones are for use in audio amplifiers.

    Googling Audio transformers will give a few other sources of supply and more information.
    Last edited by peterb; 14-04-2008 at 01:57 PM.
    (\__/)
    (='.'=)
    (")_(")

    Been helped or just 'Like' a post? Use the Thanks button!
    My broadband speed - 750 Meganibbles/minute

  9. #9
    Registered User
    Join Date
    Feb 2010
    Posts
    1
    Thanks
    0
    Thanked
    0 times in 0 posts

    Re: Problems Connecting Laptop To PA / Amp

    Hi chaps the fix for this is very simple you just need a small in line piece of kit called a ground loop isolator, i have one its excellent and supresses all noise.

    hope this helps

    about a fiver all in on ebay

  10. #10
    Registered User
    Join Date
    Nov 2010
    Location
    bristol uk
    Posts
    3
    Thanks
    0
    Thanked
    0 times in 0 posts

    Re: Problems Connecting Laptop To PA / Amp

    I run a karaoke/disco and uses a laptop I have had the same problem as you when by power supply is plugged in i got a horrible screeching sound with buzzing you have got to options number 1 is make up a short 0.5 metre one gang extension lead with out a earth cable that stops it not recommended but handy for a quick fix or you can go to maplins and buy a ground loop isolator but the down fall is if you use a live mixing desk you will have to get the appropriate adapters to plug into the desk and too your laptop the website where i get some stuff from is maplins.co.uk I hope that solves your problem I got all mackie active speakers and a mackie mixing desk

  11. #11
    Va Va Voom Lowe's Avatar
    Join Date
    Jul 2003
    Location
    Newcastle Under Lyme
    Posts
    6,736
    Thanks
    321
    Thanked
    356 times in 265 posts
    • Lowe's system
      • Motherboard:
      • Gigabyte Z97MX Gaming 5
      • CPU:
      • Intel i5 4690K
      • Memory:
      • 16GB Crucial Ballistix Tactical
      • Storage:
      • Crucial M550 256GB and 1TB spindle drive
      • Graphics card(s):
      • Palit Geforce GTX1080 Jetstream
      • PSU:
      • EVGA 600w
      • Case:
      • Coolermaster Silencio 352 m-ATX
      • Operating System:
      • Win 7/Mac OSX
      • Monitor(s):
      • 27" 1080p AOC, Oculus Rift CV1
      • Internet:
      • 200mb Virgin VIVID

    Re: Problems Connecting Laptop To PA / Amp

    Even easier - buy a simple semi pro 2 channel USB soundcard that has balanced outputs. No more noise, and better sound too

  12. #12
    Registered User
    Join Date
    Dec 2010
    Posts
    1
    Thanks
    0
    Thanked
    0 times in 0 posts

    Re: Problems Connecting Laptop To PA / Amp

    Quote Originally Posted by turnitup View Post
    I run a karaoke/disco and uses a laptop I have had the same problem as you when by power supply is plugged in i got a horrible screeching sound with buzzing you have got to options number 1 is make up a short 0.5 metre one gang extension lead with out a earth cable that stops it not recommended but handy for a quick fix or you can go to maplins and buy a ground loop isolator but the down fall is if you use a live mixing desk you will have to get the appropriate adapters to plug into the desk and too your laptop the website where i get some stuff from is maplins.co.uk I hope that solves your problem I got all mackie active speakers and a mackie mixing desk
    Hi
    I run virtual dj through a numark djio on my sony vaio i had the exact problem and your quick fix done the job fine!!!!

    I can't see the problem with keeping the set up like that? Does the transformer really need an earth anyway???

    Remi

  13. #13
    Registered User
    Join Date
    Nov 2010
    Location
    bristol uk
    Posts
    3
    Thanks
    0
    Thanked
    0 times in 0 posts

    Cool Re: Problems Connecting Laptop To PA / Amp

    generley electrictions will not recommend it but thats by far the cheapest way so i use it all the time if im using my laptop to dj with as long as the amp,mixer and lighting rig is earthed you should be fine technicly transformers should have an earth on them but also i think if theres a fuse and something goes wrong that would go pop just dont put it in to be pac tested

  14. #14
    Registered User
    Join Date
    Aug 2011
    Location
    belfast
    Posts
    1
    Thanks
    0
    Thanked
    0 times in 0 posts

    Re: Problems Connecting Laptop To PA / Amp

    hi this is the first time i have used this site. i am trying to find an amp that will allow me to connect to my computer that will also allow me to connect my dj speakers into. i am trying to take up djing by must use the laptop. if you have any suggestion i would be very thankful.

  15. #15
    Va Va Voom Lowe's Avatar
    Join Date
    Jul 2003
    Location
    Newcastle Under Lyme
    Posts
    6,736
    Thanks
    321
    Thanked
    356 times in 265 posts
    • Lowe's system
      • Motherboard:
      • Gigabyte Z97MX Gaming 5
      • CPU:
      • Intel i5 4690K
      • Memory:
      • 16GB Crucial Ballistix Tactical
      • Storage:
      • Crucial M550 256GB and 1TB spindle drive
      • Graphics card(s):
      • Palit Geforce GTX1080 Jetstream
      • PSU:
      • EVGA 600w
      • Case:
      • Coolermaster Silencio 352 m-ATX
      • Operating System:
      • Win 7/Mac OSX
      • Monitor(s):
      • 27" 1080p AOC, Oculus Rift CV1
      • Internet:
      • 200mb Virgin VIVID

    Re: Problems Connecting Laptop To PA / Amp

    Laptop > USB soundcard (with balanced outs!) > PA amp > Speakers.

  16. #16
    Admin team peterb's Avatar
    Join Date
    Aug 2005
    Location
    Southampton
    Posts
    19,192
    Thanks
    2,804
    Thanked
    3,347 times in 2,649 posts
    • peterb's system
      • Motherboard:
      • Nascom 2
      • CPU:
      • Z80B
      • Memory:
      • 48K 8 bit memory on separate card
      • Storage:
      • Audio cassette tape - home built 5.25" floppy drive
      • Graphics card(s):
      • text output (composite video)
      • PSU:
      • Home built
      • Case:
      • Home built
      • Operating System:
      • Nas-sys
      • Monitor(s):
      • 12" monocrome composite video input
      • Internet:
      • No networking capability on this machine

    Re: Problems Connecting Laptop To PA / Amp

    Quote Originally Posted by turnitup View Post
    generley electrictions will not recommend it but thats by far the cheapest way so i use it all the time if im using my laptop to dj with as long as the amp,mixer and lighting rig is earthed you should be fine technicly transformers should have an earth on them but also i think if theres a fuse and something goes wrong that would go pop just dont put it in to be pac tested
    Certainly isn't the cheapest way... funerals are very expensive! If the equipment needs an earth, and you remove it, and the equipment develops a fault that would have used the earth connection, it will use you as the earth path instead. The fuse will blow - but probably too late for you. Even if there is an alternative earth through the signal leads, you stand a good chance of trashing the equipment - those paths aren't designed to carry fault currents - and neither are you! (Oh, and if it is someone else that is injured/killed during a gig you may find yourself prosecuted/sued, if it is as a result of you tampering with the equipment)

    DO NOT DISCONNECT PROTECTIVE EARTH LEADS
    - unless you are absolutely certain that it is safe to do so.

    Quote Originally Posted by Lowe View Post
    Laptop > USB soundcard (with balanced outs!) > PA amp > Speakers.
    Indeed. Better sound, more professional set up.
    (\__/)
    (='.'=)
    (")_(")

    Been helped or just 'Like' a post? Use the Thanks button!
    My broadband speed - 750 Meganibbles/minute

Page 1 of 2 12 LastLast

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. My experience with Windows XP Pro x64 Edition
    By Paul Adams in forum Software
    Replies: 7
    Last Post: 20-04-2007, 11:59 PM
  2. Dell Latitude X1 Review!
    By dawson in forum Reader Reviews
    Replies: 2
    Last Post: 01-11-2005, 02:12 PM
  3. Laptop fan problems continue, homemade moving parts lubricant?
    By Marcos in forum PC Hardware and Components
    Replies: 13
    Last Post: 17-04-2005, 04:59 PM
  4. Problems connecting
    By Geist in forum PC
    Replies: 5
    Last Post: 15-03-2005, 07:51 PM
  5. connecting laptop, help
    By serlex in forum PC Hardware and Components
    Replies: 2
    Last Post: 04-02-2004, 04:12 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •