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Thread: DIY BMU build

  1. #1
    Join Date: Nov 2015

    Location: Wolverhampton

    Posts: 4,508
    I'm Oliver.

    Default DIY BMU build

    Here it is. All built but need to swap the 10a MCB for 6a MCBs

    It has removed the intermittent powerline adapter noise. Only problem is, I have a buzzing sound now.

    Any suggestions?
    Technics SP10 MK2 > Phonomac AT-1010 tonearm > Ortofon Kontrapunkt b > Wizard Jfet MC Valve Phonostage (Telefunken Valves) > Slagle AVC Passive Preamp > Firebottle Monoblocks (Telefunken Valves) > Fisual S-Flex Speaker Cable > Pioneer CS-77A Speakers > OLTECH Cables Throughout

  2. #2
    Join Date: Jan 2009

    Location: Essex

    Posts: 16,734
    I'm openingabottleofwine.

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    Looking good Oliver,

    But the MCBOs need to be ganged, so that if one trips out due to a fault condition, both live (115V) conductors are disconnected. Ideally you should use a 2-pole ganged RCBO.
    Have you listened to this month's choice in the Album Club?

    Barry

  3. #3
    Join Date: Nov 2015

    Location: Wolverhampton

    Posts: 4,508
    I'm Oliver.

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    Quote Originally Posted by Barry View Post
    Looking good Oliver,

    But the MCBOs need to be ganged, so that if one trips out due to a fault condition, both live (115V) conductors are disconnected. Ideally you should use a 2-pole ganged RCBO.
    They are connected by a metal pin, Barry. Of one trips, they both trip. Tried and tested.
    Technics SP10 MK2 > Phonomac AT-1010 tonearm > Ortofon Kontrapunkt b > Wizard Jfet MC Valve Phonostage (Telefunken Valves) > Slagle AVC Passive Preamp > Firebottle Monoblocks (Telefunken Valves) > Fisual S-Flex Speaker Cable > Pioneer CS-77A Speakers > OLTECH Cables Throughout

  4. #4
    Join Date: Jan 2009

    Location: Essex

    Posts: 16,734
    I'm openingabottleofwine.

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    Quote Originally Posted by Bigman80 View Post
    They are connected by a metal pin, Barry. Of one trips, they both trip. Tried and tested.
    Ah - I couldn't see that from the photo. It would be better still if a two-pole residual current circuit breaker was used, to provide protection against asymmetrical current leakage.
    Have you listened to this month's choice in the Album Club?

    Barry

  5. #5
    Join Date: Oct 2008

    Location: Glasgowshire

    Posts: 6,420
    I'm availableforweddingsAndBarmitzvas.

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    The buzzing probably means you have DC on your mains.
    Get a DC blocker in there Oliver, either in the chassis if you have room or an external box between the mains feed on the wall and BMU.

    Fitted one to my Airlink unit recently, buzzing is gone.


    THe BMU, whats your perception of sound quality changes?
    Whether your glass is half empty or half full I hope that half is beer


  6. #6
    Join Date: Nov 2015

    Location: Wolverhampton

    Posts: 4,508
    I'm Oliver.

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    Quote Originally Posted by Gazjam View Post
    The buzzing probably means you have DC on your mains.
    Get a DC blocker in there Oliver, either in the chassis if you have room or an external box between the mains feed on the wall and BMU.

    Fitted one to my Airlink unit recently, buzzing is gone.


    THe BMU, whats your perception of sound quality changes?
    There is a DC blocker in there, it does reduce mechanical hum.

    Well, it seems the BMU is not having the desired effect. I am getting more hum now than previously. I have stripped everything out and put in place a multi plug which I built. Very simple, just wired with standard flex and switchless sockets and stared plugging things in one after the other.

    I have some hum on the Phonostage which I hadn't realised but the Rothwell SUT is adding to that. The IC cables I use aren't shielded so that needs addressing. But it's 90% quieter without the BMU. Looks like it'll be for sale.

    Barry,

    I agree but it was just put together with bits I had to see if it would be beneficial and it's not, in my house anyway.

    So the BMU is out, DIY multiplication is in.
    Technics SP10 MK2 > Phonomac AT-1010 tonearm > Ortofon Kontrapunkt b > Wizard Jfet MC Valve Phonostage (Telefunken Valves) > Slagle AVC Passive Preamp > Firebottle Monoblocks (Telefunken Valves) > Fisual S-Flex Speaker Cable > Pioneer CS-77A Speakers > OLTECH Cables Throughout

  7. #7
    Join Date: Oct 2008

    Location: Glasgowshire

    Posts: 6,420
    I'm availableforweddingsAndBarmitzvas.

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    Mines is hardwired and my mains is shit...may be a factor.
    Whether your glass is half empty or half full I hope that half is beer


  8. #8
    Join Date: Nov 2015

    Location: Wolverhampton

    Posts: 4,508
    I'm Oliver.

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    Right, I take it back

    I've taken the SUT out and the phonostage and put the Vivant in with direct MC connection.

    Volume on full and the mains sounded horrific but NO hum. Dropped the BMU back in volume on full and voila, almost silent.

    So diagnosis is - Wizard phonostage needs a bit of help to dispel the hum and the SUT needs some position help.

    Sound with the BMU in is clean. Almost added a bit of depth and dimension.
    Technics SP10 MK2 > Phonomac AT-1010 tonearm > Ortofon Kontrapunkt b > Wizard Jfet MC Valve Phonostage (Telefunken Valves) > Slagle AVC Passive Preamp > Firebottle Monoblocks (Telefunken Valves) > Fisual S-Flex Speaker Cable > Pioneer CS-77A Speakers > OLTECH Cables Throughout

  9. #9
    Join Date: Oct 2012

    Location: The Black Country

    Posts: 3,923
    I'm Alan.

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    Way to go ....

    We'll try some fixes with the Wizard to see where it is lacking, could be that a resistive link to the chassis may be beneficial.

  10. #10
    Join Date: Nov 2015

    Location: Wolverhampton

    Posts: 4,508
    I'm Oliver.

    Default

    Right, Rothwell SUT back in with the Vivant and......... No hum, hiss or nasty sounds. SO.....it's the bloody Wizard phonostage.
    Technics SP10 MK2 > Phonomac AT-1010 tonearm > Ortofon Kontrapunkt b > Wizard Jfet MC Valve Phonostage (Telefunken Valves) > Slagle AVC Passive Preamp > Firebottle Monoblocks (Telefunken Valves) > Fisual S-Flex Speaker Cable > Pioneer CS-77A Speakers > OLTECH Cables Throughout

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