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Thread: An experiment in amplification

  1. #51
    Join Date: Dec 2008

    Location: East Riding of Yorkshire these days

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    I'm Shaun.

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    Quote Originally Posted by Mystic Mac View Post
    Existentialism on a audiophile forum..... bravo I say.

    Thank you guys, I’ve really enjoyed reading this thread. I can identify with quite a bit of what has been said.
    Lincolnshire my true, spiritual home by the sea. Last place I lived was Tetney. So nice to be so rural and so close to the sea.

  2. #52
    Join Date: Dec 2008

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    After a few weeks of using this new amp system I have found that backing off the gain controls on the power amps has improved the sound a helluva lot. It also enables me to use the preamp's rotary volume control in it's sweetest area away from almost 'off'. I still haven't used the system to play female vocal jazz so don't yet know how it will handle such a thing. There is however much less coarseness in the upper mid/treble since backing off the gain controls.

  3. #53
    Join Date: Apr 2012

    Location: N E Kent

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    I'm Geoff.

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    Maybe you had a touch of input overload on the power amps.
    It is impossible for anything digital to sound analogue, because it isn't analogue!

  4. #54
    Join Date: Aug 2009

    Location: Staffordshire, England

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    I'm Martin.

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    What pre-amp are you using? Might be better off with something with no gain so you can keep the power amps on full output.
    Current Lash Up:

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

  5. #55
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    Quote Originally Posted by walpurgis View Post
    Maybe you had a touch of input overload on the power amps.
    Geoff, that is exactly what it sounded like, at least to my ears.

  6. #56
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    Quote Originally Posted by Macca View Post
    What pre-amp are you using? Might be better off with something with no gain so you can keep the power amps on full output.
    Martin, I am currently using my old PrimaLuna Prologue 3 preamp.

  7. #57
    Join Date: Aug 2009

    Location: Staffordshire, England

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    I'm Martin.

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    I'd try a passive with them then. There might be gold there.
    Current Lash Up:

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

  8. #58
    Join Date: Dec 2008

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    Quote Originally Posted by Macca View Post
    I'd try a passive with them then. There might be gold there.
    Wouldn't a pair of RCA inline attenuators do a better job as the current preamp has a built in phono stage and you never know do you

  9. #59
    Join Date: Mar 2017

    Location: Seaford UK

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    I'm Dennis.

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    The problems of level matching are cropping up numerous times on the forum, and they are easy to resolve if a clear understanding is obtained.

    Of course it would be much better if the industry standardised levels more, as is the case in broadcasting where numerous pieces of equipment are swapped into service all the time, necessitating interchangeability, and hence compatibility to facilitate this.

    All amplifiers have a range of level operation which gives an optimum performance, the lowest level limited by quiescent noise in the amp, and the highest limited by design, this involving gain structure, devices, and power rail voltages.

    Optimum matching between pre and power amps is achieved when their respective ranges are matched; that is, when the lower level limits are operating together, and the higher ones also, but a bit of headroom is always a bonus on a preamp.

    When these ranges are matched, the best S/N ratio is achieved, and the volume pot will give the best range of volume over its rotation; none of the 'crammed up at one end' and easily too loud*, or turned up full, but too quiet, because the power amplifier is not being fed enough voltage to drive it to produce the desired volume.

    *Many pots are also poorly matched at the lower end of their range, resulting in possible unequal levels from each channel at that end of the pot range.

    The CD player industry likes to have O/Ps of much higher voltage than most other line level sources - at a guess they consider that this level is best high so that it does not in any way limit performance; it is always good to have level and/or gain in hand to 'play with'.

    Many line level sources have about a 150mV O/P level, tuners for example, and so a CD player fed into a preamplifier will, compared with this, overload the I/P by about 21 to 22dB. This is problematic when switching from one source to another for obvious reasons, and so attenuating the higher CD O/P is sensible.

    In line attenuators are convenient and negate the need for fitting internal components either in the CD player O/P or in the preamp I/P ccts.

    The vinyl problem is that cartridges are very individual in their characteristics, this resulting from the designer's attempts using innovation, to reach higher performances, and as a result characteristics, including O/P levels vary, as do the needs or not, for capacitative loading, hence the adjustment available in many preamps.

  10. #60
    Join Date: Aug 2009

    Location: Staffordshire, England

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    I'm Martin.

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    Quote Originally Posted by Haselsh1 View Post
    Wouldn't a pair of RCA inline attenuators do a better job as the current preamp has a built in phono stage and you never know do you
    Well you could try. I don't like them myself.
    Current Lash Up:

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

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