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    VTA SP12 Popping Noise

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    guentherj2

    Posts : 50
    Join date : 2013-06-22
    Location : Bellingham, WA

    VTA SP12 Popping Noise

    Post by guentherj2 on Sun Sep 29, 2013 12:13 pm

    Greetings All:

    My standard operating practice is to have my volume control set at low before changing/selecting different sources. However, when I forget to turn the volume down or have the volume at a mid-level setting and move the source selector to Phono from a different source I hear a loud POP. This only happens the first time I select phono. If after the first POP I move the source selector to a different source and then back to Phono it doesn't happen - just the first time.

    Is this normal or indicative of a problem?

    Also - when the SP12 source selector is on Tuner, I get a some noise at every volume volume notch when changing the volume control.

    Maybe this is normal and I just need to be dilligent about keeping my volume down when changing the source selector control?

    Any similar experiences or thoughts?

    Thanks,

    John

    Zimmer64

    Posts : 113
    Join date : 2013-01-29
    Age : 52
    Location : Switzerland

    Re: VTA SP12 Popping Noise

    Post by Zimmer64 on Sun Sep 29, 2013 2:22 pm

    I have the same symptoms with my SP 14 and my CD player. It even affects my volume control. The pop of the source selector happens only once The pops of the stepped attenuator goes away after playing some music. How strange is that?.... My guess is that it is static or some grounding issue, but I could not figure it out.

    arledgsc

    Posts : 340
    Join date : 2012-11-30
    Location : SF Bay CA

    Re: VTA SP12 Popping Noise

    Post by arledgsc on Sun Sep 29, 2013 3:29 pm

    Slight DC shifts in potential could be heard as a pop as the various inputs are connected and disconnected with the switch.  This can be heightened with capacitive coupling of the stages since the caps can store a charge.  And since the phono stage has more gain then it may just simply amplify the "pop" more.  But should be of no concern except for the annoying noise - if not loud enough to damage you speakers.

    deepee99

    Posts : 1336
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: VTA SP12 Popping Noise

    Post by deepee99 on Thu Oct 24, 2013 6:38 pm

    Sounds like one or more of your tubes in the line preamp is microphonic. That will produce exactly the symptoms you describe; I had some noisy 6CG7s in my SP-13 that did this.

    kevco

    Posts : 70
    Join date : 2009-07-16
    Location : Aldan, PA, USA

    Re: VTA SP12 Popping Noise

    Post by kevco on Mon Oct 28, 2013 12:06 pm

    My Sp-12 has recently developed some popping noises while turning the stepped volume attenuator up or down especially in the low volume range. I have experienced some pinging noises in the past while moving the attenuator due to microphonic line stage tubes. This however is constant no matter what tubes are installed. I'm wondering if the attenuator needs to be or even can be cleaned...Anybody have knowledge on this? I've got Deoxit and Dustoff. I'm kind of embarrassed to mention that due to space limitations in my home, my cat's litter box is within the same open plan area as my system and the dust produced by adding new clumping litter to the box tends to float throughout the area and must be constantly removed from surfaces. This is fine clay dust, invasive stuff.

    deepee99

    Posts : 1336
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: VTA SP12 Popping Noise

    Post by deepee99 on Mon Oct 28, 2013 12:22 pm

    kevco wrote:My Sp-12 has recently developed some popping noises while turning the stepped volume attenuator up or down especially in the low volume range.  I have experienced some pinging noises in the past while moving the attenuator due to microphonic line stage tubes.  This however is constant no matter what tubes are installed.  I'm wondering if the attenuator needs to be or even can be cleaned...Anybody have knowledge on this?  I've got Deoxit and Dustoff.  I'm kind of embarrassed to mention that due to space limitations in my home, my cat's litter box is within the same open plan area as my system and the dust produced by adding new clumping litter to the box tends to float throughout the area and must be constantly removed from surfaces.  This is fine clay dust, invasive stuff.
    We just take the cat-box outside to fill it, let the dust-storm settle for a couple of minutes, then bring it back inside. QED

    Jim McShane

    Posts : 154
    Join date : 2011-10-19
    Location : South Suburban Chicago

    Re: VTA SP12 Popping Noise

    Post by Jim McShane on Mon Oct 28, 2013 12:48 pm

    arledgsc is right on the money, a shift in DC level is almost always the cause. Often when you change selector switch positions you often connect to circuitry with either charged up caps that discharge and cause the noise or vice-versa. From a design point of view often you'll see very high value resistors used to keep the cap charged or to keep it discharged when not in the active circuitry.

    It's always a good idea to have clean contacts, good tubes with good contact in the socket, etc. but those are not often the cause of the pop. As arledgsc said as well - if it isn't too loud to damage something don't worry about it.

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