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Thread: Is the halfway position on tone controls actually the 'flat' setting?

  1. #1
    Join Date: Apr 2012

    Location: N E Kent

    Posts: 51,624
    I'm Geoff.

    Default Is the halfway position on tone controls actually the 'flat' setting?

    Well? Question as above. Bet it's not necessarily the case, but how do you tell without measuring equipment? I'm sure you can't!

    Potentiometers will I reckon vary depending on how good they are or how the maker decides they want them to operate.

    And of course there's the 'Lin' or 'Log' thing. How does that influence the situation?

    And then there's the amplifier circuit. Does it necessarily give a flat response at an anticipated control position?


    Yes. I'm asking 'cos I'm using an amplifier with tone controls (a rare experience ).

  2. #2
    Join Date: Aug 2008

    Location: Suffolk, UK

    Posts: 1,473
    I'm Paul.

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    If the pots and other components in the tone circuit are 100% accurate then yes. In reality no.... you can check using a computer quite easily, if you have a good soundcard. Just find an online signal generator and sweep through the frequencies while measuring the (attenuated) output.

    I imagine that there are very few dual gang pots that are matched well between channels. The better option are separate tone controls for each channel.
    ~Paul~

  3. #3
    Join Date: Sep 2017

    Location: Dublin

    Posts: 506
    I'm Pavel.

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    Some better amps use stepped tone controls. And several hi-end Sony and Yamaha models have a set of relays that remove the tone controls from the signal path when they're set to the middle position.

  4. #4
    Join Date: Apr 2012

    Location: N E Kent

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    I'm Geoff.

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    At the moment I'm playing with a seemingly well regarded classic British integrated amp from the seventies. A Cambridge Audio P80 that I bought for a bit of fun. I must admit, the sound quality comes as a surprise. It's remarkably good! But, I feel the tone controls are not exactly accurate. They are pots by the way.

    I bought this recently 'cos when I first got involved with Hi-Fi the Cambridge P50 was hailed as being exceptional and when the P80 arrived a few years later it was considered to be even better.

  5. #5
    Join Date: Aug 2008

    Location: Suffolk, UK

    Posts: 1,473
    I'm Paul.

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    Tone controls are a bit of a funny one. If you have a tone defeat you can usually tell that the tone circuit has a detrimental effects. However, overall the tone corrections can be less detrimental that the effect of the room, which can pften be the worst offender.
    ~Paul~

  6. #6
    Join Date: Apr 2012

    Location: London

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    I'm James.

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    Those of us who have moved to the dark side (digital) regard tone controls as a primitive throwback. We expect gain and Q, also frequency centre, impulse response equalisation, and even assymmetry as starting points in a system.
    So saying, who's to say that the frequency response of a vintage amp at 'flat' might have been intended to be neutral by the designer? Amps of that vintage were often purposefully skewed across their frequency range one way or another by a few fractions of a decibel to work as intended where intended, and no shame in that. If it sounds good it is good!

    Sent from my GT-I9195 using Tapatalk

  7. #7
    Join Date: Aug 2009

    Location: Staffordshire, England

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    I'm Martin.

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    Distortion levels might also vary with FR. So you've got more than one thing to measure
    Current Lash Up:

    TEAC VRDS 701T > Sony TAE1000ESD > Krell KSA50S > JM Labs Focal Electra 926.

  8. #8
    Join Date: Apr 2012

    Location: N E Kent

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    I'm Geoff.

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    Quote Originally Posted by Jazid View Post
    who's to say that the frequency response of a vintage amp at 'flat' might have been intended to be neutral by the designer?
    That's one of the questions I was asking. No doubt there is no agreed standard.

  9. #9
    Join Date: Mar 2017

    Location: Seaford UK

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    I'm Dennis.

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    If we use a tone control amp, we accept that it is a valid procedure to adjust FR to ameliorate other factors, and therefore, since we do it by ear, any verification of the resulting response is relatively irrelevant, and only of academic interest.

    Regarding channel balance, Quad used a tilt system in which as one channel gained top, the other lost it, and so channel balance becomes an irrelevance with this also.

  10. #10
    Join Date: Oct 2012

    Location: The Black Country

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    I'm Alan.

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    Quote Originally Posted by Pharos View Post
    Quad used a tilt system in which as one channel gained top, the other lost it, ..........
    You've got that a little wrong Dennis, the tilt is applied to both channels. A very effective system to give a small change in presentation.

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