Attn: SDA Gurus, need a little help...

ND13
ND13 Posts: 7,601
edited June 2005 in Vintage Speakers
When listening to my SDA 2A's, last night, I noticed when the volume was tuned up to about 0db on the HK dial, the highs faded away a little then after turning it back down foer a few seconds every thing was normal. I noticed it a few times. I wasn't even pushing them hard at all. Should this go away when the new tweeters are installed or is there some other cause or fix?

Any help will be much appreciated.

Thanks,

Noel
"SOME PEOPLE CALL ME MAURICE,
CAUSE I SPEAK OF THE POMPITIOUS OF LOVE"
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  • hoosier21
    hoosier21 Posts: 4,411
    edited June 2005
    sounds like the poly switch was tripped, either by too much power, too much clipping, or over time the polyswitch has weakened and needs replaced.

    Do a search here and see some pictures of the polyswitch and it's replacement.

    Call Ken for parts.

    Good luck

    FWIW, I will guess it was the HK clipping. A 90watt rec., ran wide open into these speakers will drain that rec. fast.
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  • ND13
    ND13 Posts: 7,601
    edited June 2005
    FWIW, I will guess it was the HK clipping [/B][/QUOTE]

    I've pushed the RTA 8TL's and the Monitor 10A's well beyond that with nary a glitch. Will look into the polyswitch.

    Thanks, Any other suggestions?
    "SOME PEOPLE CALL ME MAURICE,
    CAUSE I SPEAK OF THE POMPITIOUS OF LOVE"
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  • BlueMDPicker
    BlueMDPicker Posts: 7,569
    edited June 2005
    The polyswitch (yellow-gold) on a 2B crossover is located immediately to the right of the "P1" label on the PCB in this picture:

    attachment.php?s=&postid=302849
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  • reeltrouble1
    reeltrouble1 Posts: 9,312
    edited June 2005
    Agree with Hoosier, let me add the more you do this the weaker the polyswitches are likely to become.

    RT1
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  • ND13
    ND13 Posts: 7,601
    edited June 2005
    Don't worry it won't be done again. BMD, guess I'll be needing your guidance sooner than later. BTW, it only did it on the left.
    "SOME PEOPLE CALL ME MAURICE,
    CAUSE I SPEAK OF THE POMPITIOUS OF LOVE"
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  • F1nut
    F1nut Posts: 50,592
    edited June 2005
    Originally posted by hoosier21

    FWIW, I will guess it was the HK clipping. A 90watt rec., ran wide open into these speakers will drain that rec. fast.

    Without a doubt.

    I'd change the poly's anyway and then start looking for more power.
    Political Correctness'.........defined

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  • BlueMDPicker
    BlueMDPicker Posts: 7,569
    edited June 2005
    Originally posted by ND13
    BMD, guess I'll be needing your guidance sooner than later.

    Take a look at the SDA 2B crossover upgrade thread. I did a step-by-step. If you're pulling the crossovers for a polyswitch replacement, shame on you if you don't replace all the gruntball components. ;)
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  • ND13
    ND13 Posts: 7,601
    edited June 2005
    Originally posted by BlueMDPicker
    Take a look at the SDA 2B crossover upgrade thread. I did a step-by-step. If you're pulling the crossovers for a polyswitch replacement, shame on you if you don't replace all the gruntball components. ;)

    Don't worry, I wouldn't do it if I it wasn't going to be done right the first time. What's another $30-40, if the improvement is so dramatic, right?
    "SOME PEOPLE CALL ME MAURICE,
    CAUSE I SPEAK OF THE POMPITIOUS OF LOVE"
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  • ND13
    ND13 Posts: 7,601
    edited June 2005
    Originally posted by F1nut
    Without a doubt.

    I'd change the poly's anyway and then start looking for more power.

    Then why would it only do it on the left ? I'm not saying I think anyone is wrong, just seems that if it were clipping, it would do it on both channels????

    Also it has never clipped on the other speakers, at higher output levels, running both A and B's together..

    And I am looking into getting more power to them. Probably an
    SS/tube pre set-up. Anyone like Adcom/Dodd ELP setup????
    "SOME PEOPLE CALL ME MAURICE,
    CAUSE I SPEAK OF THE POMPITIOUS OF LOVE"
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  • BlueMDPicker
    BlueMDPicker Posts: 7,569
    edited June 2005
    Originally posted by ND13
    Then why would it only do it on the left ? I'm not saying I think anyone is wrong, just seems that if it were clipping, it would do it on both channels????

    Polyswitches can "break down" over time if run to the point of tripping. If you suspect one, replace them both (low cost peace of mind.)

    The SDAs may be lower nominal impedance than the other speakers you've run on the same gear -- thereby putting more of a demand on the output stage and causing earlier clipping.
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  • heiney9
    heiney9 Posts: 25,179
    edited June 2005
    And I am looking into getting more power to them. Probably an
    SS/tube pre set-up. Anyone like Adcom/Dodd ELP setup????

    Anybody tried this, are they compatible? Bet it would sound sweet!

    H9
    "Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul!
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  • ND13
    ND13 Posts: 7,601
    edited June 2005
    Hell, I guess I'll just take 'em to Goodwill, for the tax writeoff..;) :D:D
    "SOME PEOPLE CALL ME MAURICE,
    CAUSE I SPEAK OF THE POMPITIOUS OF LOVE"
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  • heiney9
    heiney9 Posts: 25,179
    edited June 2005
    Originally posted by ND13
    Hell, I guess I'll just take 'em to Goodwill, for the tax writeoff..;) :D:D

    Aaahhh......which Goodwill store did you say you were taking those to? When do they open? LOL

    H9

    P.S. I know where I can get a cable for those!!!! :eek:
    "Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul!
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  • ND13
    ND13 Posts: 7,601
    edited June 2005
    Originally posted by heiney9
    Aaahhh......which Goodwill store did you say you were taking those to? When do they open? LOL

    H9

    P.S. I know where I can get a cable for those!!!! :eek:

    I was wondering if anyone would get that..
    "SOME PEOPLE CALL ME MAURICE,
    CAUSE I SPEAK OF THE POMPITIOUS OF LOVE"
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