RCA Caps on unused inputs - worth it or not?

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  • zingo
    zingo Posts: 11,258
    edited March 2013
    EndersShadow wrote: »
    So in looking at a picture of the back of my Citation 11 pre, I dont want to use it on Pre-Amp Output 2, Tape Output 1, or Tape Output 2 is what your saying correct?

    Yes, you do not want to use shorting plugs on any unused outputs. Caps or covers would be okay, but never the shorting plugs which ground the center pin.
    Jake
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  • bthogan
    bthogan Posts: 151
    edited March 2013
    headrott wrote: »
    Have you experimented with placing end caps on your RCA inputs and listening for differences in the audio signal? Or, are you assuming that the end caps do nothing?

    The force is strong with this one.
    lanchile wrote: »
    I work fixing and build amps, testing them with oscilloscope (my boss place) and all this is crab!

    Oscilloscope? Oh my brother...
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  • lanchile
    lanchile Posts: 560
    edited March 2013
    EndersShadow wrote: »
    Yes, those are the ones.



    I can always count on you for the straight up truth with no BS :smile:



    So in looking at a picture of the back of my Citation 11 pre, I dont want to use it on Pre-Amp Output 2, Tape Output 1, or Tape Output 2 is what your saying correct?

    Attachment not found.

    OK, Talking about "caps" have you ever "recapped" your OLD pre-amp with new capacitors? Because this is an old unit and electrolytic caps dry-out with time. That will be something that is more important than worry about those useless RCA covers caps! Beside those old RCA terminals are not worthy to cover (cheap).
    Make it simple...Make it better!
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  • lanchile
    lanchile Posts: 560
    edited March 2013
    bthogan wrote: »
    The force is strong with this one.



    Oscilloscope? Oh my brother...
    Yes, oscilloscope!!! Do you know what that is? Do you know how to use one?...Oh my brother!!!
    Make it simple...Make it better!
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  • ZLTFUL
    ZLTFUL Posts: 5,648
    edited March 2013
    Did Rav get a new screen name?
    "Some people find it easier to be conceited rather than correct."

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  • bthogan
    bthogan Posts: 151
    edited March 2013
    lanchile wrote: »
    Yes, oscilloscope!!! Do you know what that is? Do you know how to use one?...Oh my brother!!!

    ear.jpg
    ear.jpg 10.4K
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  • lanchile
    lanchile Posts: 560
    edited March 2013
    bthogan wrote: »
    ear.jpg

    Well that is not an oscilloscope! That is an ear!!! lol....
    Make it simple...Make it better!
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  • EndersShadow
    EndersShadow Posts: 17,590
    edited March 2013
    lanchile wrote: »
    OK, Talking about "caps" have you ever "recapped" your OLD pre-amp with new capacitors? Because this is an old unit and electrolytic caps dry-out with time. That will be something that is more important than worry about those useless RCA covers caps! Beside those old RCA terminals are not worthy to cover (cheap).

    I haven't. Right now it's not here, it shows up tomorrow lol. I will have to evaluate it when it gets here.

    Also worth it or not I probably will get some just to keep them clean for the future.
    "....not everything that can be counted counts, and not everything that counts can be counted." William Bruce Cameron, Informal Sociology: A Casual Introduction to Sociological Thinking (1963)
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  • lanchile
    lanchile Posts: 560
    edited March 2013
    EndersShadow wrote: »
    I haven't. Right now it's not here, it shows up tomorrow lol. I will have to evaluate it when it gets here.

    Also worth it or not I probably will get some just to keep them clean for the future.

    if you can get an E.S.R meter and check those old electrolytic caps in your old pre-amp you will see that many caps will be out of their original values and will affect the sound. instead investing in those "fancy" RCA covers...invest in new capacitors in your old pre-amp. That will be a big plus!
    Make it simple...Make it better!
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  • steveinaz
    steveinaz Posts: 19,538
    edited March 2013
    I have some of these I bought a long time ago---so I use them. Do they make any difference? I don't know. It's one of those things where it certainly doesn't "hurt" to use them, just don't expect miracles.
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  • lanchile
    lanchile Posts: 560
    edited March 2013
    your pre-amp was build around 1973...that is about 40 years old unit and I bet most of those electrolytic capacitors are out of values already!
    Make it simple...Make it better!
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  • Speedskater
    Speedskater Posts: 495
    edited March 2013
    The chance of any interference getting in through as small a hole as an RCA jack are extremely low, the chance of any of this micro-wave interference attacking your hi-fi are zero. But if micro-wave interference does attack your hi-fi it would take a very special oscilloscope to detect it.

    How did you guys get a picture of my O-scope?
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  • lanchile
    lanchile Posts: 560
    edited March 2013
    This is the schematic of your pre-amp. as you can see, when the selector is not engaged to the a source...it is like nothing was there, because it cuts the connection to it. so if you are not using them...Nothing is coming to it. This is the first time I hear someone worrying about this thing. Just worry about replacing all those old capacitors that are over 40 years old that are dying.

    http://manuals.harman.com/hk/Service%20Manual/Citation%20eleven%20sm.pdf
    Make it simple...Make it better!
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  • halo71
    halo71 Posts: 4,603
    edited March 2013
    Oh how did we ever get along without these caps? I plan on picking some up this weekend when I buy cable risers. :twisted::rolleyes:
    --Gary--
    Onkyo Integra M504, Bottlehead Foreplay III, Denon SACD, Thiel CS2.3, NHT VT-2, VT-3 and Evolution T6, Infinity RSIIIa, SDA1C and a few dozen other speakers around the house I change in and out.
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  • lanchile
    lanchile Posts: 560
    edited March 2013
    halo71 wrote: »
    Oh how did we ever get along without these caps? I plan on picking some up this weekend when I buy cable risers. :twisted::rolleyes:

    lol, get me some too! I wonder if you can pick some caps for my MacBook that has the USB inputs without caps, My friend that is a dishwasher in a restaurant told me that I should have these USB inputs covered because if I do, it will increase speed and performance too. :lol:
    Make it simple...Make it better!
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  • zingo
    zingo Posts: 11,258
    edited March 2013
    lanchile wrote: »
    if you can get an E.S.R meter and check those old electrolytic caps in your old pre-amp you will see that many caps will be out of their original values and will affect the sound. instead investing in those "fancy" RCA covers...invest in new capacitors in your old pre-amp. That will be a big plus!

    I understand that you would prefer he recap his preamp before getting RCA covers. Than you for the opinion (not that I don't agree with it), but that is not what he was asking about. Make your suggestion once, then move on if you don't feel like participating in what the OP is specifically posting. If someone want to spend their money on something that they think might make a difference in their audio system, more power to them.
    Jake
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  • F1nut
    F1nut Posts: 50,557
    edited March 2013
    lanchile wrote: »
    My friend that is a dishwasher in a restaurant told me that I should have these USB inputs covered because if I do, it will increase speed and performance too. :lol:

    At least he tried them, which is more than can be said for you.
    Political Correctness'.........defined

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  • ratster
    ratster Posts: 324
    edited March 2013
    I don't know anything about O-scopes but,they do use one on Audio Advisors video demonstrating how the caps are supposed to reduce noise.
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  • BlueFox
    BlueFox Posts: 15,251
    edited March 2013
    ratster wrote: »
    I don't know anything about O-scopes but,they do use one on Audio Advisors video demonstrating how the caps are supposed to reduce noise.

    Haven't seen it, but it certainly seems probable. Of course, if there isn't much stray EMI in the vicinity of the pre then there will be little to reduce. Basically, they can't hurt, and for a minor cost they might help. I have the Cardas on my pre and I can't say if there is any difference or not.
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  • [Deleted User]
    [Deleted User] Posts: 7,658
    edited March 2013
    Actually if you read the service manual on the classic Marantz 7C preamp they say to place shorting plugs (supplied by the manufacturer) on the unused inputs (especially the phono) during testing and listening. This is from Saul Marantz who should know what he's talking about.
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  • EndersShadow
    EndersShadow Posts: 17,590
    edited March 2013
    Kenneth Swauger wrote: »
    Actually if you read the service manual on the classic Marantz 7C preamp they say to place shorting plugs (supplied by the manufacturer) on the unused inputs (especially the phono) during testing and listening. This is from Saul Marantz who should know what he's talking about.

    Yup the guy who sold me the Citation 11 told me he found the shorting plugs that came with it and included them. Thats why this whole thing started.....
    "....not everything that can be counted counts, and not everything that counts can be counted." William Bruce Cameron, Informal Sociology: A Casual Introduction to Sociological Thinking (1963)
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  • unc2701
    unc2701 Posts: 3,587
    edited March 2013
    EndersShadow wrote: »
    Yup the guy who sold me the Citation 11 told me he found the shorting plugs that came with it and included them. Thats why this whole thing started.....

    This ^

    Input shorting plugs can absolutely reduce noise on a lot of preamp designs and it wasn't uncommon for older receivers and pres to ship with them. As for non-shorting caps, there are many, many, many better investments that will do more to improve sound, but hey, if you like how they look and you want to take it for a whirl, go for it.
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  • steveinaz
    steveinaz Posts: 19,538
    edited March 2013
    For the record, mine are simply the "caps" not shorting plugs.
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  • halo71
    halo71 Posts: 4,603
    edited March 2013
    So...Am I the only 'round here wearing aluminum foil hats? Ya know....to keep the aliens from reading my mind? :cheesygrin:


    All jokes aside. Anyone using caps or shorting plugs. Can you tell a difference?
    --Gary--
    Onkyo Integra M504, Bottlehead Foreplay III, Denon SACD, Thiel CS2.3, NHT VT-2, VT-3 and Evolution T6, Infinity RSIIIa, SDA1C and a few dozen other speakers around the house I change in and out.
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  • unc2701
    unc2701 Posts: 3,587
    edited March 2013
    An Audio Experience pre I had awhile back was prone to a slight hum/hiss. Shorting plugs on the open inputs took it from about 4-5 ft distance where you could hear it down to head-right-next-to-the-speaker.

    I have also used them to eliminate hum on guitar amps.
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  • SCompRacer
    SCompRacer Posts: 8,498
    edited March 2013
    Kenneth Swauger wrote: »
    Actually if you read the service manual on the classic Marantz 7C preamp they say to place shorting plugs (supplied by the manufacturer) on the unused inputs (especially the phono) during testing and listening. This is from Saul Marantz who should know what he's talking about.

    IIRC back in the day some Adcom pre amps came with shorting plugs in the phono input.

    Anybody ever try longing plugs?:cheesygrin:
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  • [Deleted User]
    [Deleted User] Posts: 7,658
    edited March 2013
    That's the long and the short of it.,
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  • zingo
    zingo Posts: 11,258
    edited March 2013
    halo71 wrote: »
    All jokes aside. Anyone using caps or shorting plugs. Can you tell a difference?

    Caps simply cover the socket, shorting plugs short the input to ground.
    Jake
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  • madmax
    madmax Posts: 12,434
    edited March 2013
    A cap which connects only to the ground (not a shorting plug) most likely protects against RFI. I use them, never heard a difference. But, it is cheap insurance against HF getting into the circuitry.
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  • drumminman
    drumminman Posts: 3,396
    edited March 2013
    I used simple, inexpensive Parts Express RCA plugs to fill all the unused inputs on a NAD C160 pre I used to have in my system. Lots of unused inputs = lots of plugs. These were not shorting and I could definitely hear a difference. It wasn't night and day, but music sounded a little cleaner.

    Not a big $ investment either.
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