SDA 2B rebuild

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Comments

  • My ears tell me something isn't right...trying to figure out what it is.
  • I should probably add that it's entirely possible that nothing is wrong and I simply don't care for the sound of these speakers.
  • xschop
    xschop Posts: 2,036
    edited January 29
    Do you listen to Klipsch for any extended periods? Could explain some things. Freq. range burn-out of the eustachian tubes. It happens.
  • Gardenstater
    Gardenstater Posts: 2,014
    bigmontana wrote: »
    My ears tell me something isn't right...trying to figure out what it is.

    Totally reasonable and proactive approach you are taking, and it enabled you to confirm that one driver was better than the others, presumably it sounds better too?

    Just a couple ideas:

    1) Try to make sure that room acoustics are not playing a part in what you are *measuring*, both with your ears and your spectrum analyzer.

    2) Standing waves in the cabinet could be producing some destructive interference and the BH5 would be the cure for that. Nobody knows what the optimum amount and placement is. The key is not to put it where it will inhibit energy transfer to the passives, at least of the most direct and coherent backwaves. No reason why *a little* behind the drivers and possibly to their sides is going to destroy the sound and it will most likely clarify it and improve resolution and detail and all that good stuff.

    3) You have yet to upgrade the internal wiring, correct?

    George / NJ

    Polk 7B main speakers, std. mods+ (1979, orig owner)
    Martin Logan Dynamo sub w/6ft 14awg Power Cord
    Crown D150 amp
    Logitech Squeezebox Touch Streamer w/EDO applet
    iFi nano iDSD DAC
    iPurifier3
    iDefender w/ iPower PS
    Custom Steve Wilson 1m UPOCC Interconnect
    iFi Mercury 0.5m OFHC continuous cast copper USB cable
    Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
    Custom Vibration Isolation Speaker Stands and Sub Platform
  • xschop wrote: »
    Do you listen to Klipsch for any extended periods? Could explain some things. Freq. range burn-out of the eustachian tubes. It happens.

    No. I've never cared for the sound of Klipsch speakers. In all honesty, it's been so long since I've heard a pair that I don't remember what it was about them that I didn't like.
    My 2-channel setup has been Goldenear Triton 7's for the past 5 years or so.

    I have tried the SDA's in two different rooms and noticed the same thing in both. Also, I currently have them in the same room as the Goldenears, so it's easy to compare.

    You are correct, I have not replaced any internal wiring.
  • dromunds
    dromunds Posts: 9,361
    How much break-in time? Those caps need a LOT of break-in, they will sound not so good for periods prior to that substantial break-in time completing
  • VR3
    VR3 Posts: 24,811
    How are you placing them in the room? Any pics?

    Also don't put resistors on top of caps, bad things can happen, like burned up stuff 😜🚀🚀🚀
    - Not Tom

    "No, that's silly talk. Dude, you can't possibly be this audio dumb so quit the act." - Doro
  • Gardenstater
    Gardenstater Posts: 2,014
    I would check out the manual and make sure you're following the room placement guidelines:

    https://polksda.com/pdfs/SDA1C.pdf
    George / NJ

    Polk 7B main speakers, std. mods+ (1979, orig owner)
    Martin Logan Dynamo sub w/6ft 14awg Power Cord
    Crown D150 amp
    Logitech Squeezebox Touch Streamer w/EDO applet
    iFi nano iDSD DAC
    iPurifier3
    iDefender w/ iPower PS
    Custom Steve Wilson 1m UPOCC Interconnect
    iFi Mercury 0.5m OFHC continuous cast copper USB cable
    Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
    Custom Vibration Isolation Speaker Stands and Sub Platform
  • xschop
    xschop Posts: 2,036
    bigmontana wrote: »
    xschop wrote: »
    Do you listen to Klipsch for any extended periods? Could explain some things. Freq. range burn-out of the eustachian tubes. It happens.

    No. I've never cared for the sound of Klipsch speakers. In all honesty, it's been so long since I've heard a pair that I don't remember what it was about them that I didn't like.
    My 2-channel setup has been Goldenear Triton 7's for the past 5 years or so.

    I have tried the SDA's in two different rooms and noticed the same thing in both. Also, I currently have them in the same room as the Goldenears, so it's easy to compare.

    You are correct, I have not replaced any internal wiring.

    Was being silly, but at the same time, just trying to convey that being accustomed to a particular pair of speakers, then switching to another set will usually make you think something is missing or over-emphasized.

    Hopefully you just need longer cap burn-in as another has stated.
  • Gardenstater
    Gardenstater Posts: 2,014
    edited January 29
    Those Goldenear's seem like they might be pretty nice speakers.......maybe you're just spoiled! :D

    But seriously, another thing to consider is that the domes and voice coils in new tweeters do smooth out considerably SQ wise with considerable breakin. I proved that myself recently and posted the freq. response curves before and after, in the SL2000 thread.

    Also, you didn't mention whether or not you tested the cabinets for air leakage, you know, the push and hold test on the passives and timing how long it takes the MW's to return.

    What about the proper amount of polyfill? Is it there?
    Post edited by Gardenstater on
    George / NJ

    Polk 7B main speakers, std. mods+ (1979, orig owner)
    Martin Logan Dynamo sub w/6ft 14awg Power Cord
    Crown D150 amp
    Logitech Squeezebox Touch Streamer w/EDO applet
    iFi nano iDSD DAC
    iPurifier3
    iDefender w/ iPower PS
    Custom Steve Wilson 1m UPOCC Interconnect
    iFi Mercury 0.5m OFHC continuous cast copper USB cable
    Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
    Custom Vibration Isolation Speaker Stands and Sub Platform
  • I gave them 150 hours of break in time before I started using them. With listening time since then, they're probably around 200 hours. I did hear a noticeable improvement after the break in compared to immediately after assembling them. Should I expect much change beyond 200 hours?

    Room placement is in accordance with the manual: 6.5' apart, 5' from the nearest wall, zero toe-in. Listening position can be adjusted, but is usually 9' away. The SDA effect sounds fantastic, so I don't think I'm getting any bad reflections.

    I did have an air leak when I first assembled them, but replaced a couple of damaged gaskets and they seem to be good now. Push test takes just over 3 seconds for the MW's to return.

    The polyfill is the same as it was when I got them. There's one piece that lays flat along the back wall and two pieces that are rolled up and placed behind the MW's. The polyfill only reaches down to about the top of the passive.

    VR3 wrote: »
    Also don't put resistors on top of caps, bad things can happen, like burned up stuff 😜🚀🚀🚀
    Are you being serious here? If the concern is heat, I do have an air gap between them. If there is another reason, please elaborate. I could move the resistor to the bottom of the board to get it farther away from the cap, but I've never heard this recommendation before.

    Thank you to everyone for the assistance. Hopefully dromunds is right and they will get better with even more break in time.
  • pitdogg2
    pitdogg2 Posts: 19,451
    An air gap is good. @VR3 is serious and has seen results trust that. Some resistors get very hot. It's one reason if a resistor is 5w and the same resistor comes in 10-12 watt we pick the larger wattage to help dissipate heat better. Cheap ins.
  • VR3
    VR3 Posts: 24,811
    I wouldn't put a resistor anywhere close to a cap if you can help it. Atleast 3/8 inch or more distance

    I have seen some disastrous results from resistors burning up stuff.
    - Not Tom

    "No, that's silly talk. Dude, you can't possibly be this audio dumb so quit the act." - Doro