Results 1 to 7 of 7

Thread: Help needed from Electronic Experts

  1. #1
    Senior Member Guido's Avatar
    Join Date
    Apr 2003
    Location
    Germany
    Posts
    2,503

    Help needed from Electronic Experts

    I need some help from our electronic experts.
    Found the attached schematic of the input terminal from my main amps. These caps seem to be something like a subsonic filter. Problem is that they are electrolytic and carry the signal. Weird is that they are reversly polarized.

    Do i need them?
    Attached Images Attached Images  

  2. #2
    Senior Member LE15-Thumper's Avatar
    Join Date
    Feb 2004
    Location
    Winnipeg, Canada
    Posts
    602
    Quote Originally Posted by Guido
    I need some help from our electronic experts.
    Found the attached schematic of the input terminal from my main amps. These caps seem to be something like a subsonic filter. Problem is that they are electrolytic and carry the signal. Weird is that they are reversly polarized.

    Do i need them?
    Do you need them ? Yes and no. It depends on whether or not there is a DC offset on the other side of them and/or a dc offset from your pre-amp. It is usually always a good idea to have coupling caps on the input of an amplifier. You don't know the condition of the signal is coming in.
    Being in series, you have an effective value of half the total. I would try a high quality 10uf@50V in place of one cap in each channel and put a jumper in each channel where the second cap is.
    Worst case is your bass output will suffer. You will then have to bump up the value of this cap untill you are happy with the sound. Usually 1uf and up is plenty for input coupling but it depends on the input impedance of the circuit following the cap.
    LE15-Thumper
    "Give me JBL, or give me death"

  3. #3
    Senior Member LE15-Thumper's Avatar
    Join Date
    Feb 2004
    Location
    Winnipeg, Canada
    Posts
    602
    Also, forgot to mention. They are back-to-back in that polarity to effectivley give you a non-polarized cap. Being that music is an ac voltage it is best to always use a nice fat value non-polar cap with a small .1uf bypass as well (connected in parallel) Say, like a 10uf polycarb with a .1uf film foil bypass.

    There are a lot of combinations you can try. Different values and different types of caps can really affect sound quality. Have some fun, fool around with it. Almost anything will sound better than Electrolytics. Some guys even try tanatlums with film-foil bypass.
    LE15-Thumper
    "Give me JBL, or give me death"

  4. #4
    Senior Member Guido's Avatar
    Join Date
    Apr 2003
    Location
    Germany
    Posts
    2,503
    Thanks for help!

    I'll mess around with it

  5. #5
    Senior Member
    Join Date
    Apr 2003
    Location
    Australia
    Posts
    7,942
    Quote Originally Posted by Guido
    I need some help from our electronic experts.
    Found the attached schematic of the input terminal from my main amps. These caps seem to be something like a subsonic filter. Problem is that they are electrolytic and carry the signal. Weird is that they are reversly polarized.

    Do i need them?
    I would leave them in there and bypass with one 0.047 film foil across both electros.

    The 220uf is large enough to prevent any phase shift in the passband which is important, the natural rise in esr is the only issue but that is a subjective matter.

    The Doctor

  6. #6
    Senior Member Guido's Avatar
    Join Date
    Apr 2003
    Location
    Germany
    Posts
    2,503
    Quote Originally Posted by Ian Mackenzie
    I would leave them in there and bypass with one 0.047 film foil across both electros.

    The 220uf is large enough to prevent any phase shift in the passband which is important, the natural rise in esr is the only issue but that is a subjective matter.

    The Doctor
    Thanks for that Ian.
    But why exactly a 0.047 uF? I have some nice 0.01 uF Wima film foil. Not good?

  7. #7
    Senior Member
    Join Date
    Apr 2003
    Location
    Australia
    Posts
    7,942
    Guido.

    0.01 will be fine

    The Doctor - Who

    Quote Originally Posted by Guido
    Thanks for that Ian.
    But why exactly a 0.047 uF? I have some nice 0.01 uF Wima film foil. Not good?

Thread Information

Users Browsing this Thread

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

Similar Threads

  1. Electronic Crossover
    By speakerdave in forum Electronic Crossovers
    Replies: 37
    Last Post: 02-23-2011, 03:33 PM
  2. Expert Help Urgently Needed For Vital Audio Preservation Project!
    By sonofagun in forum General Audio Discussion
    Replies: 18
    Last Post: 03-10-2005, 03:56 PM
  3. 5234 Electronic Crossover
    By mick c in forum Lansing Product General Information
    Replies: 2
    Last Post: 02-07-2005, 06:00 AM
  4. Test Equipment Needed to Tune Cabinet
    By 2$Bill in forum Lansing Product Technical Help
    Replies: 1
    Last Post: 01-15-2004, 07:36 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
  •