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Thread: Hiraga upgrade - Bypass capacitors

  1. #11
    Join Date: Dec 2015

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    hmmm
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  2. #12
    Join Date: Aug 2010

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    Quote Originally Posted by Dalek Supreme D L View Post
    Assuming the Hiraga is as was designed and not already bastardised why would you want to mess around with an amp designed by a legend, designed to be what it was mean't to be.

    Its a piece of audio history, its value lies in what it was mean't to be. Mess with it and it ceases to be a Hiraga.

    Amen.

    S.

  3. #13
    Join Date: Oct 2012

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    Quote Originally Posted by Radford Revival View Post
    Don't forget that with large PSU capacity the more you have to worry about inrush limiting.
    A good point yes but a few of the schematics I saw already had 150,000uF per rail! There are large thermistors designed for just this job available and it would be a good idea to use one in the primary circuit yes
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  4. #14
    Join Date: Sep 2013

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    Quote Originally Posted by Radford Revival View Post
    Don't forget that with large PSU capacity the more you have to worry about inrush limiting.
    And following the rush ( reminds me of the Neil Young song ) the ability of diode bridges to handle such capacitance is a major concern. The old rule of thumb, that is still immently sensible is 1000uf for every amp of current drawn. The LT4320 using 4x N channel hexfets at 50 amps each, might provide ability for such high capacitance, but are then limited by Rds on of the mosfet and voltage can be no higher than 70v.

  5. #15
    Join Date: Dec 2015

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    I don't want to bastardise - but it's quite old and I'm sure some of the components must be out of spec - though I don't know. It sounds extremely good. In fact I was planning on a post about it compared to my Cary monsters.
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  6. #16
    Join Date: Nov 2008

    Location: North Down /Northern Ireland/ UK

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    Quote Originally Posted by farflungstar View Post
    I don't want to bastardise - but it's quite old and I'm sure some of the components must be out of spec - though I don't know. It sounds extremely good. In fact I was planning on a post about it compared to my Cary monsters.
    I deliberately used that word as the initial post suggested more to me than a simple check up and more a modification. It is possible that components may be off spec and it would be worth getting them measured. If all still in spec and no bits known to fail suddenly then I would leave alone. Changing components out even if same values can change the sound unless they are identical parts but the problem will be that manufacturing changes to those parts might alter the sound.

    I know some folks aren't precious about designers work and as long as they get a perceived improvement will happily alter a classic design but from a collectors point of view, and yours and any amp designed by that legendary designer fall under that heading then altering them will kill the collectors value, and ruin what that designer designed that amp to be.

    Put it simply a Lectron amp or yours unaltered I would buy, but a messed with one, nope wouldn't touch it with a barge pole. That's me and others mileage will vary. You pays your money and makes your choice.
    Regards Neil

  7. #17
    Join Date: Feb 2008

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    I would first off' just replace the power supply caps for decent quality new ones, and posibly upgrade the diodes, or bridge rectifiers for better ones, and see how much it changes things first before going too drastic, you may end up turning something you currently like, into something somewhat diffrent to what you remember!
    Just my ramblings.
    A...
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  8. #18
    Join Date: Oct 2012

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    Quote Originally Posted by Dalek Supreme D L View Post
    I deliberately used that word as the initial post suggested more to me than a simple check up and more a modification. It is possible that components may be off spec and it would be worth getting them measured. If all still in spec and no bits known to fail suddenly then I would leave alone. Changing components out even if same values can change the sound unless they are identical parts but the problem will be that manufacturing changes to those parts might alter the sound.

    I know some folks aren't precious about designers work and as long as they get a perceived improvement will happily alter a classic design but from a collectors point of view, and yours and any amp designed by that legendary designer fall under that heading then altering them will kill the collectors value, and ruin what that designer designed that amp to be.

    Put it simply a Lectron amp or yours unaltered I would buy, but a messed with one, nope wouldn't touch it with a barge pole. That's me and others mileage will vary. You pays your money and makes your choice.
    I don't class Hiraga as a good designer personally... Well known, yes. Good, No.
    Arkless Electronics-Engineered to be better. Tel. 01670 530674 (after 1pm)

    Modded Thorens TD150, Audio Technica AT-1005 MkII, Technics EPC-300MC, Arkless Hybrid MC phono stage, Arkless passive pre, Arkless 50WPC Class A SS power amp, (or) Arkless modded Leak Stereo 20, Modded Kef Reference 105/3's
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  9. #19
    Join Date: Dec 2015

    Location: Alicante. Spain.

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    I'm Adrian.

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    Thanks guys. I don't want to change the design so sorry if my initial post suggested otherwise. I do however need to investigate an issue and thought it might be a good chance to pimp up some components

    The issue I have is that with it connected there is a grounding issue - touching the fingerlift causes a hum. If I float the ground on the preamp it goes away. Not sure if this is a design flaw or if something is wrong. It's not an issue with other amps.

    Also the red neon rocker switch for power doesn't completely go out - it's always on albeit at a low level.

    Saying this it sounds extremely good - in some areas beating my Cary 805c monsters.

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