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Thread: Lightspeed Attenuator

  1. #1
    leo's Avatar
    leo is offline Circuit Junkie & DIY Room Forum Leader
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    Default Lightspeed Attenuator

    I've been interested in trying George's Lightspeed Attenuators for a while http://members.optusnet.com.au/~georgehifi/ , details of the Lightspeed are on here http://www.diyaudio.com/forums/showt...194&highlight=


    I got these particular modules from Paul Hynes who did his own remote control version, he kindly did a small batch available to the diyers, details are further on in the diyaudio thread .

    Anyway heres some pics of the thing I've been using for a few weeks.
    I housed it in a small aluminum enclosure from Maplin. The infra red transmitter is enclosed inside a plastic project box fed from AA batteries, keypad is made by Storm from Farnell
    The remote is big and junky but does the job









    The vol adjustments is nice and smooth, I keep my finger held down on the up button until the sound is audible, I then tap it until its at the required volume

    The balance control is a handy feature, it seems to work well for the less than perfect matched LDR's, mine was a little off centre, a few taps on the balance sorted it nicely.

    The volume and balance re-sets after power cycling

    I'm really pleased with this thing, sound quality is better than any of my normal pots (Alps blue and black) and also betters my Vishay Dale Attenuator
    Obviously works best with high input impedance amps though
    Cheers,
    Leo

  2. #2
    Join Date: Sep 2008

    Location: Hampshire

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    Hi Leo

    I am thinking about building a Lightspeed. Did you source the LDRs within the UK? And how much did your kit cost?

    Richard

  3. #3
    leo's Avatar
    leo is offline Circuit Junkie & DIY Room Forum Leader
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    http://www.diyaudio.com/forums/showt...58#post1771358

    Board for LDR's VCCS £60 built and tested + £3 P&P , bare pcb and application note £12 + £2.24 P&P
    Board for IR transmitter and board for IR receiver, built modules (pair) £49.60 + £3 P&P, bare pcb and application note £13.77 + £2.27 P&P

    Storm keypad £12.82 http://uk.farnell.com/storm-interfac...eys/dp/9809953

    LDR's , matched or unmatched, I tried them unmatched because of the balance control Paul included with his version which works very well http://www.diyaudio.com/forums/showt...hreadid=148518
    Or from Farnell £1.85 each http://uk.farnell.com/silonex/nsl-32...in_merch=true&

    Aluminum case was from Maplin, it was about 6 quid
    Plastic case for transmitter was from Maplin, a few quid
    Cable, battery clips etc from Maplin too

    Details for a simple version without remote on vero http://diyaudioprojects.com/Solid/DI...ve-Attenuator/
    Last edited by leo; 04-09-2009 at 18:03. Reason: Correct part number added, ta Richard
    Cheers,
    Leo

  4. #4
    Join Date: Sep 2008

    Location: Hampshire

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    Default

    Quote Originally Posted by leo View Post
    http://www.diyaudio.com/forums/showt...58#post1771358

    Board for LDR's VCCS £60 built and tested + £3 P&P , bare pcb and application note £12 + £2.24 P&P
    Board for IR transmitter and board for IR receiver, built modules (pair) £49.60 + £3 P&P, bare pcb and application note £13.77 + £2.27 P&P

    Storm keypad £12.82 http://uk.farnell.com/storm-interfac...eys/dp/9809953

    LDR's , matched or unmatched, I tried them unmatched because of the balance control Paul included with his version which works very well http://www.diyaudio.com/forums/showt...hreadid=148518
    Or from Farnell £1.85 each http://uk.farnell.com/silonex/nsl-32...o-p/dp/3692218

    Aluminum case was from Maplin, it was about 6 quid
    Plastic case for transmitter was from Maplin, a few quid
    Cable, battery clips etc from Maplin too

    Details for a simple version without remote on vero http://diyaudioprojects.com/Solid/DI...ve-Attenuator/
    Hi Leo

    Thanks for the info. I've just ordered a couple of LDR stereo sets from Uriah at DIYAUDIO.

    The Lightspeed is getting a lot of positive reviews of late.

    Richard

  5. #5
    Join Date: Mar 2009

    Location: Elland

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    I'm David.

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    ... just out of interest... what does it do?
    CS Port TAT2 - Benz LPS - Funkfirm Houdini - DS Audio Vinyl Ionizer - CS Port C3EQ - Kondo G70 - Kondo Gakuoh II - Maxonic TW1100 MKII - Isol-8 SubStation Integra

  6. #6
    leo's Avatar
    leo is offline Circuit Junkie & DIY Room Forum Leader
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    Quote Originally Posted by hamish_gill View Post
    ... just out of interest... what does it do?
    Its a passive pre which is different to the norm it doesn't have the usual pot or switched attenuator in the signal path, it uses LDR's
    Cheers,
    Leo

  7. #7
    Join Date: Mar 2009

    Location: Elland

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    I'm David.

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    hmm... perhaps an option for those who desire a rc for thier beresfords....
    CS Port TAT2 - Benz LPS - Funkfirm Houdini - DS Audio Vinyl Ionizer - CS Port C3EQ - Kondo G70 - Kondo Gakuoh II - Maxonic TW1100 MKII - Isol-8 SubStation Integra

  8. #8
    Join Date: Apr 2009

    Location: W Mids

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    An interesting idea, reminds me of the channel switching on old Fender guitar amps. What source and amp are you using it with Leo? I've never really liked any passive preamps and would be worried about driving this circuit directly from a TDA1541.

    I'd be inclined to put a little buffer after the control, any thoughts?

    (this may have been discussed at length on the DIYaudio thread, but haven't quite read all 96 pages yet!)

    Cheers
    Tom

  9. #9
    Join Date: May 2008

    Location: Surrey

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    I'm Rob.

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    I put together a Lightspeed this morning on a piece of perfboard. I sourced the LDRs from Farnell and just picked four out of the bag of 25. (truth is I did not know how to match them!) One of the easiest things I have built. Worked first time (apart from the pot working back to front - but easy to fix).

    I have only listened to it for about an hour, both with headphones and through speakers. Very promising. Will hve to plumb it in to my main system for the acid test.





    Last edited by Puffin; 30-08-2009 at 15:54.
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  10. #10
    Join Date: Apr 2008

    Location: Cheltenham U.K

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    I'm John.

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    Ska Audio do a pretty cheap version using just two LDRs called the Optivol: http://www.ska-audio.com/
    Last edited by jonners; 30-08-2009 at 18:33. Reason: Added info

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