1. OCAU Merchandise now available! Check out our 20th Anniversary Mugs, Classic Logo Shirts and much more! Discussion here.
    Dismiss Notice

5 Dollar AV-710 Capacitor Mod [Phase 1]

Discussion in 'Electronics & Electrics' started by decayed.cell, Aug 1, 2006.

  1. Kaine[zof]

    Kaine[zof] Member

    Joined:
    Mar 22, 2004
    Messages:
    2,179
    Location:
    Melbourne
    Thread resurrection! (Hey, it's a good thread)

    I just want to have a bit of a discussion about the cutoff frequency formula used in the first post.

    For completeness:
    OK so for those of us who aren't using headphones with massive impedance, it would seem that 22uF won't quite cut it. I'll use 2 popular headphones as examples;

    Koss PortaPro: 60ohm impedance

    With the AV710 default caps (10uF)
    1 / (2*Pi*60*0.00001) = ~265Hz

    With the original mod caps (22uF)
    1 / (2*Pi*60*0.000022) = ~120Hz

    I chose these mainly because i have a set but also because they are considered possibly the best sounding headphones in their price range. They're very popular and everyone should own a set.

    Audio Technica ATH-AD900: 35ohm impedance

    With the AV710 default caps (10uF)
    1 / (2*Pi*35*0.00001) = ~454Hz

    With the original mod caps (22uF)
    1 / (2*Pi*35*0.000022) = ~206Hz

    Chosen because they're known for having an excellent sound without an amplifier.

    Now i know my portapros seem to lack a bit of bass but 265hz cutoff is pretty huge. Can someone confirm/deny what i'm doing here? Are there any dangers associated with putting in capacitors as big as 220uF?
     
    Last edited: Oct 27, 2007
  2. OP
    OP
    decayed.cell

    decayed.cell Member

    Joined:
    Mar 8, 2005
    Messages:
    1,189
    Location:
    Melbourne
    You can put in as large caps as you like, a 265hz cutoff will mean that you will lose a lot of bottom end :p
     
  3. Kaine[zof]

    Kaine[zof] Member

    Joined:
    Mar 22, 2004
    Messages:
    2,179
    Location:
    Melbourne
    well according to my spreadsheet (i knew those school spreadsheet skills would come in handy one day) 220uF would give me about a 10Hz cutoff for the PortaPros and 24/25Hz cutoff for the AD900s

    It's a shame RS don't stock the 220uF Nichicon FG caps. they go straight from 100uF to 470uF :( Good thing there's Panasonic to save the day. There's a 6.5mm 220uF FM series (super low ESR) that fit the bill :D
     
  4. stevodude

    stevodude Member

    Joined:
    Jun 2, 2003
    Messages:
    799
    Location:
    Mackay
    hehe, I read this thread ages ago, and liked the idea of modding the av710.
    amazing that this thread was resurected a couple of days ago, as yesterday I just mod'd the rear outputs of my av710 with some Nichicon muse 100uf 25v hehehe, bit large on the voltage side of things, but meh.
    using the above calculation cutoff is around 45hz... :)

    Note: dodgy photo taken with my phone, capacitors soldered to back of card due to a tad larger than the piddly little 10u's that where on it :)
    [​IMG]
     
  5. Kaine[zof]

    Kaine[zof] Member

    Joined:
    Mar 22, 2004
    Messages:
    2,179
    Location:
    Melbourne
    nice! are they soldered in parallel or did you remove the 10uF caps?
     
  6. stevodude

    stevodude Member

    Joined:
    Jun 2, 2003
    Messages:
    799
    Location:
    Mackay
    removed teh old caps...
     
  7. almando

    almando Member

    Joined:
    Apr 2, 2007
    Messages:
    12
    Location:
    Hobart
    I've got a pair of alessandro ms-1 (32ohm) and i've ordered a av710.
    what would be the best replacement caps to the run the headphones directly?
     
  8. OP
    OP
    decayed.cell

    decayed.cell Member

    Joined:
    Mar 8, 2005
    Messages:
    1,189
    Location:
    Melbourne
    Well using the formula, the original caps would produce this cutoff

    1 / (2*Pi*32*0.00001) = ~497Hz

    So to get the cutoff down nice and low to get a fuller sound you would need relatively large caps, say around 100uF Nichicons

    1 / (2*Pi*32*0.00010) = ~50Hz

    or you could go with higher spec caps which would probably be better such as 330uF

    1 / (2*Pi*32*0.00033) = ~15Hz

    But in all honesty I think you're doing your MS-1s a bit of injustice by pairing it with an AV-710. I think you would make the most of them with an amp and a better soundcard such as an E-MU 0404 or a Juli@ or an X-Fi
     
  9. almando

    almando Member

    Joined:
    Apr 2, 2007
    Messages:
    12
    Location:
    Hobart
    thanks for the advise Decayed.Cell, greatly appreciated.
    I'll do the mod and see how it sounds. Will upgrade soundcard and get an amp when i have enough dosh :p.

    P.S what voltage caps should i get?
     
  10. OP
    OP
    decayed.cell

    decayed.cell Member

    Joined:
    Mar 8, 2005
    Messages:
    1,189
    Location:
    Melbourne
    Theres hardly much voltage going through the card so 25V would do
     
  11. TERRA Operative

    TERRA Operative Member

    Joined:
    Jul 8, 2005
    Messages:
    6,925
    Location:
    Niraikanai
    What's the best way to measure the input impedance of my amplifier? With a multimeter/ Or does it need to be measured at a certain frequency?
     
  12. dakiller

    dakiller (Oscillating & Impeding)

    Joined:
    Jun 27, 2001
    Messages:
    8,069
    Location:
    3844
    Just take it as >10k.

    You could open it up and track down the input resistor that goes to ground but thats work you shouldn't have to do, stick with 10k and 1-3hz corner for an amp and you'll be in the best range
     
  13. TERRA Operative

    TERRA Operative Member

    Joined:
    Jul 8, 2005
    Messages:
    6,925
    Location:
    Niraikanai
    Well, this is the input circuitry up to the first op amp or whatever. Does that make sense? I have no idea how to calculate anything from that...

    [​IMG]
    Click to view full-sized image!
     
  14. almando

    almando Member

    Joined:
    Apr 2, 2007
    Messages:
    12
    Location:
    Hobart
    Last edited: Dec 4, 2007
  15. OP
    OP
    decayed.cell

    decayed.cell Member

    Joined:
    Mar 8, 2005
    Messages:
    1,189
    Location:
    Melbourne
  16. Kaine[zof]

    Kaine[zof] Member

    Joined:
    Mar 22, 2004
    Messages:
    2,179
    Location:
    Melbourne
    i have been hanging out to mod my AV-710 but mine has an intermittent stopping problem and Chaintech won't replace it. Bastards. Sound just randomly stops, still registers on the output meter, doesn't matter if it's running high quality or what. such a piss off.
     
  17. nfenech

    nfenech Member

    Joined:
    Oct 29, 2007
    Messages:
    167
    Sorry, haven't read the whole 8 pages yet.
    Just wondering if you would still need to do this mod if you wanted to use this card for a HTPC? If you where just using the card to gr straight from the computer to the AMP?

    Thanks.

    P.S MOD looks like it might be worth it anyway! Great stuff!
     
  18. stevodude

    stevodude Member

    Joined:
    Jun 2, 2003
    Messages:
    799
    Location:
    Mackay
    Kaine[zof], is this in windows? as I had this problem with winamp when I paused a playlist, and started again, sometimes I'd get no audio, but shows on the meter...
    In the end I used foobar in windows, but now MPD with ncmpc locally and pitchfork mpd http client for my pda :)

    I'd do the mod if you are a: going to use stereo only, with amp or headphones (note you would normally need a headphone amp as the dac out on the av710 is line voltage only, no built in headphone amp as most sound cards with headphone out have built in amp.)
    If you are going to use it for htpc and watching movies with the digital out, then I wouldn't bother.
     
  19. Kaine[zof]

    Kaine[zof] Member

    Joined:
    Mar 22, 2004
    Messages:
    2,179
    Location:
    Melbourne
    i want to do the mod purely for the fun of it. The problem persists across 2 pcs with different motherboards, CPUs and RAM, in windows XP and in Debian Linux. It's the card. Even the store i sent it back to tested it and found problems but chaintech won't accept it as an RMA. so frustrating.
     
  20. almando

    almando Member

    Joined:
    Apr 2, 2007
    Messages:
    12
    Location:
    Hobart
    I replaced the two caps for the hd back surr channel with 330uf 25v caps.
    results were more bass and a richer sound running my ms-1's directly. but its still not as clear as i would like it and it doesn't sound as good as my ancient pioneer hifi with the ms-1's, it might be time to invest in an amp of some description. any ways i will put in some low esr caps when i get the chance to see if that makes any difference.
    thanks for the help Decayed.cell:)
     

Share This Page

Advertisement: