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Thread: Fancy a cheap passive pre-amp?

  1. #11
    Join Date: Aug 2011

    Location: Coventry, England UK

    Posts: 534
    I'm Simon.

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    Seems to be pros and cons to both. What about relay based attenuators? (this looks nice: http://www.khozmo.com/64_steps_relay...ttenuator.html)

  2. #12
    Join Date: Oct 2012

    Location: NE England

    Posts: 4,173
    I'm Jez.

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    Quote Originally Posted by RothwellAudio View Post
    Light Dependent Resistor is adamant that mechanical/physical contacts are a problem from an audio point of view but personally I'm not convinced.
    I disagree with him as strongly as is possible within the way things must be worded on the forum and believe that LDR's are a bad way of doing the job as they measurably add distortion.
    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
    ReVox PR99, Studer B62, Ferrograph Series 7, Tandberg TCD440, Hitachi FT-5500MkI, also FT-5500MkII
    Digital: Yamaha CDR-HD1500 (Digital Swiss army knife-CD recorder, player, hard drive, DAC and ADC in one), PC files via 24/96 sound card and SPDIF, modded Philips CD850, modded Philips CD104, modded DPA Little Bit DAC. Sennheiser HD580 cans with Arkless Headphone amp.
    Cables- free interconnects that come with CD players, mains leads from B&Q, dead kettles etc, extension leads from Tesco

  3. #13
    Join Date: Oct 2012

    Location: NE England

    Posts: 4,173
    I'm Jez.

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    Quote Originally Posted by Simon_LDT View Post
    Seems to be pros and cons to both. What about relay based attenuators? (this looks nice: http://www.khozmo.com/64_steps_relay...ttenuator.html)
    I have been meaning to build myself a relay one for a while... one of those round tuit things! I'm not offering to make these for customers.
    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
    ReVox PR99, Studer B62, Ferrograph Series 7, Tandberg TCD440, Hitachi FT-5500MkI, also FT-5500MkII
    Digital: Yamaha CDR-HD1500 (Digital Swiss army knife-CD recorder, player, hard drive, DAC and ADC in one), PC files via 24/96 sound card and SPDIF, modded Philips CD850, modded Philips CD104, modded DPA Little Bit DAC. Sennheiser HD580 cans with Arkless Headphone amp.
    Cables- free interconnects that come with CD players, mains leads from B&Q, dead kettles etc, extension leads from Tesco

  4. #14
    Join Date: Sep 2013

    Location: North Island New Zealand

    Posts: 1,757
    I'm Chris.

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    Quote Originally Posted by Simon_LDT View Post
    Seems to be pros and cons to both. What about relay based attenuators? (this looks nice: http://www.khozmo.com/64_steps_relay...ttenuator.html)
    It is honest by admitting there is a design issue with conventional pots and signal paths, as it
    seeks a partial different solution. But it has the same problem, that the signal path still engages
    contacts. And it is more expensive.

  5. #15
    Join Date: Sep 2013

    Location: North Island New Zealand

    Posts: 1,757
    I'm Chris.

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    Quote Originally Posted by Arkless Electronics View Post
    I disagree with him as strongly as is possible within the way things must be worded on the forum and believe that LDR's are a bad way of doing the job as they measurably add distortion.
    Prove it ! , and can I strongly suggest you use a design that properly isolates cathode ground from signal ground
    before measuring. If that takes a while to design ( years ) - so be it, And also measure a conventional pot at the same time.

  6. #16
    Join Date: Oct 2012

    Location: NE England

    Posts: 4,173
    I'm Jez.

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    Quote Originally Posted by Light Dependant Resistor View Post
    Prove it ! , and can I strongly suggest you use a design that properly isolates cathode ground from signal ground
    before measuring. If that takes a while to design ( years ) - so be it, And also measure a conventional pot at the same time.
    Don't need to. I trust Lurcher's (Nick. Longdog Audio) measurements showing this... oh, and the warnings about distortion in the manufacturers data sheets for LDR's.

    And that ends my participation in the specific matter of LDR's.
    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
    ReVox PR99, Studer B62, Ferrograph Series 7, Tandberg TCD440, Hitachi FT-5500MkI, also FT-5500MkII
    Digital: Yamaha CDR-HD1500 (Digital Swiss army knife-CD recorder, player, hard drive, DAC and ADC in one), PC files via 24/96 sound card and SPDIF, modded Philips CD850, modded Philips CD104, modded DPA Little Bit DAC. Sennheiser HD580 cans with Arkless Headphone amp.
    Cables- free interconnects that come with CD players, mains leads from B&Q, dead kettles etc, extension leads from Tesco

  7. #17
    Join Date: Sep 2013

    Location: North Island New Zealand

    Posts: 1,757
    I'm Chris.

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    Quote Originally Posted by Arkless Electronics View Post
    Don't need to. I trust Lurcher's (Nick. Longdog Audio) measurements showing this... oh, and the warnings about distortion in the manufacturers data sheets for LDR's.

    And that ends my participation in the specific matter of LDR's.

    http://lunainc.com/product/optocouplers/

    "Luna Optoelectronics’ optocouplers are ideally suited for high performance audio circuits. Most “design-ins” have demonstrated proven performance benefits over silicon based audio control devices such as VCAs and FETs.

    The optocoupler is a very cost-effective way to improve the performance of your audio equipment."

  8. #18
    Join Date: Apr 2012

    Location: N E Kent

    Posts: 51,624
    I'm Geoff.

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    Quote Originally Posted by Minstrel SE View Post
    That little bear product just looks a bit cheap

    Best wishes
    Martin
    That was the point. And it sounds good!
    It is impossible for anything digital to sound analogue, because it isn't analogue!

  9. #19
    Join Date: Apr 2012

    Location: N E Kent

    Posts: 51,624
    I'm Geoff.

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    Quote Originally Posted by RothwellAudio View Post
    BTW, Black Adder is selling a nice passive here on AoS
    http://theartofsound.net/forum/showt...y-nice-indeed)
    I Know. It's lovely, but it's not £25.
    It is impossible for anything digital to sound analogue, because it isn't analogue!

  10. #20
    Join Date: Oct 2012

    Location: NE England

    Posts: 4,173
    I'm Jez.

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    I presume the XLR's are not balanced?
    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
    ReVox PR99, Studer B62, Ferrograph Series 7, Tandberg TCD440, Hitachi FT-5500MkI, also FT-5500MkII
    Digital: Yamaha CDR-HD1500 (Digital Swiss army knife-CD recorder, player, hard drive, DAC and ADC in one), PC files via 24/96 sound card and SPDIF, modded Philips CD850, modded Philips CD104, modded DPA Little Bit DAC. Sennheiser HD580 cans with Arkless Headphone amp.
    Cables- free interconnects that come with CD players, mains leads from B&Q, dead kettles etc, extension leads from Tesco

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