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Thread: N.Pass B1 Buffer DIY preamp!

  1. #11
    Join Date: Oct 2012

    Location: NE England

    Posts: 4,173
    I'm Jez.

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    Quote Originally Posted by brucew268 View Post
    Did you mean Jez's buffer design, or Nelsons Pass' design? I've been curious why reviews confirm what I've heard, such high marks for a preamp using a cheap switcher power supply. Not that I know anything about it, but I wonder if it is related to the use of matched JFET's making it less sensitive to supply... or maybe that if it's that good with an SMPS, what league it will be with a well designed linear supply? Also,since it's just a buffer, the qualities of the potentiometer/attenuator will be passed through more directly than an active preamp. Still I wonder that I liked the buffer+Alps RK27 better than the completely passive Glasshouse Takman Rex or the Glasshouse TVC. YMMV.



    McClain clan, BTW!
    My buffer design, intended to beat the Pass buffer. Simon's will have my MkII circuit with no capacitors in the signal path.

    I'll mention in passing, and for probably the 40th time, that the entire "linear supply versus SMPS" is a complete red herring in many ways.... The important thing is how the power is dealt with after the PSU, NOT the PSU itself. With a little thought as to how things are done there is no advantage to one type of supply over the other.

    There is nothing in the use of matched FET's that reduce sensitivity to supply (most buffers are types of follower and have good PSRR anyway) and nothing in "Also,since it's just a buffer, the qualities of the potentiometer/attenuator will be passed through more directly than an active preamp"
    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

  2. #12
    Join Date: Mar 2012

    Location: West Yorkshire

    Posts: 274
    I'm Bruce.

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    Quote Originally Posted by Arkless Electronics View Post
    My buffer design, intended to beat the Pass buffer. Simon's will have my MkII circuit with no capacitors in the signal path.

    I'll mention in passing, and for probably the 40th time, that the entire "linear supply versus SMPS" is a complete red herring in many ways.... The important thing is how the power is dealt with after the PSU, NOT the PSU itself. With a little thought as to how things are done there is no advantage to one type of supply over the other.

    There is nothing in the use of matched FET's that reduce sensitivity to supply (most buffers are types of follower and have good PSRR anyway) and nothing in "Also,since it's just a buffer, the qualities of the potentiometer/attenuator will be passed through more directly than an active preamp"
    Thanks for the clarification!
    Bruce

    Theories are not so much answers as questions, to be supported or undermined by experience & testing.

    Source: Audiolab 6000CDT > Calyx 24/192 DAC
    Amplification: Pass-design B1rev2 pre-amplifier > Neurochrome Modulus 686.
    Loudspeakers: Proac Response 1SC
    Cables/stands: spkr: MIT MH-750 biwire; IC: HT Truthlink; Target stands, sand-filled; Excel Cat6A 23AWG UFTP & 1attack.de Cat.7 SFTP.
    Other: Balanced AC transformer to hydra mains distr; Bass traps & Acoustic panels; Isolation: Inner tube & roller bearings; 3xZyxel ES104A switches in series w/Vreg upgrades.

  3. #13
    RothwellAudio Guest

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    Quote Originally Posted by brucew268 View Post
    Also,since it's just a buffer, the qualities of the potentiometer/attenuator will be passed through more directly than an active preamp.
    It is an active preamp. Having unity gain doesn't make it a passive preamp - it's still an active preamp.

    Quote Originally Posted by Arkless Electronics View Post
    I'll mention in passing, and for probably the 40th time, that the entire "linear supply versus SMPS" is a complete red herring in many ways.... The important thing is how the power is dealt with after the PSU, NOT the PSU itself. With a little thought as to how things are done there is no advantage to one type of supply over the other.
    I agree. The two big advantages of switching power supplies are 1) they're cheap and easy to get, and 2) the noise is high frequency stuff which is easier to filter than 100Hz ripple.


    Just as a general comment, you could easily get the impression from forums that Nelson Pass invented the buffer. He did not, and to be fair to him he does not claim he did. His original buffer circuit was just a bog standard JFET circuit which he offered as a simple DIY project. Nothing wrong with that but it's useful to put it into some perspective.

  4. #14
    Join Date: Mar 2012

    Location: West Yorkshire

    Posts: 274
    I'm Bruce.

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    Quote Originally Posted by Arkless Electronics View Post
    There is nothing in... "Also,since it's just a buffer, the qualities of the potentiometer/attenuator will be passed through more directly than an active preamp"
    Are you saying that opamps in most active gain stages don't have an influence on the sound character, let alone the influence of the shear number and config of components in many of the more complicated preamp circuits?

    Quote Originally Posted by RothwellAudio View Post
    It is an active preamp. Having unity gain doesn't make it a passive preamp - it's still an active preamp.
    Yeah, I know. I tend to sloppily, and inappropriately speak of preamps with no gain circuitry as passive even though they are powered. Thanks for differentiating. I suppose I should have said buffer vs. preamp with gain stages.
    Bruce

    Theories are not so much answers as questions, to be supported or undermined by experience & testing.

    Source: Audiolab 6000CDT > Calyx 24/192 DAC
    Amplification: Pass-design B1rev2 pre-amplifier > Neurochrome Modulus 686.
    Loudspeakers: Proac Response 1SC
    Cables/stands: spkr: MIT MH-750 biwire; IC: HT Truthlink; Target stands, sand-filled; Excel Cat6A 23AWG UFTP & 1attack.de Cat.7 SFTP.
    Other: Balanced AC transformer to hydra mains distr; Bass traps & Acoustic panels; Isolation: Inner tube & roller bearings; 3xZyxel ES104A switches in series w/Vreg upgrades.

  5. #15
    Join Date: Oct 2012

    Location: NE England

    Posts: 4,173
    I'm Jez.

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    Quote Originally Posted by RothwellAudio View Post
    It is an active preamp. Having unity gain doesn't make it a passive preamp - it's still an active preamp.


    I agree. The two big advantages of switching power supplies are 1) they're cheap and easy to get, and 2) the noise is high frequency stuff which is easier to filter than 100Hz ripple.


    Just as a general comment, you could easily get the impression from forums that Nelson Pass invented the buffer. He did not, and to be fair to him he does not claim he did. His original buffer circuit was just a bog standard JFET circuit which he offered as a simple DIY project. Nothing wrong with that but it's useful to put it into some perspective.
    LOL yes indeedy!! Buffers are one of the most common electronic circuits and used in countless numbers of products (not just hi fi!!) and have been for virtually as long as electronics has existed!

    Nelson Pass's circuit is a standard textbook circuit and in fact I was amazed he hadn't seen the obvious potential to use that circuit in its zero offset form and avoid coupling caps.... though I hear this has now been remedied...

    On SMPS the wallwart I've used on the last few things I've built has only around 3mV ripple straight out the box!
    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

  6. #16
    Join Date: Oct 2012

    Location: NE England

    Posts: 4,173
    I'm Jez.

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    Quote Originally Posted by brucew268 View Post
    Are you saying that opamps in most active gain stages don't have an influence on the sound character, let alone the influence of the shear number and config of components in many of the more complicated preamp circuits?



    Yeah, I know. I tend to sloppily, and inappropriately speak of preamps with no gain circuitry as passive even though they are powered. Thanks for differentiating. I suppose I should have said buffer vs. preamp with gain stages.
    I'm afraid I can see no link between my comment which you quote and your following question I'm certainly not saying that op amps and electronic components have no sound character! I will say that they generally have less than many people assume.... I would take reports of "night and day" differences between op amps and resistors with a whole sack of salt! Today's best IC op amps are also so good that it is, by and large, a waste of time and money to use discrete op amps any more unless you need to optimise particular parameters such as super low noise, high Voltage swing or super high current output...

    An interesting point (well for some) is that many op amps have such good PSRR as to be virtually immune to the quality of the power they are supplied with. Many are so good in this respect that you could deliberately inject several Volts of interference on the Voltage rails and you would hear nothing but the intended music coming from the op amp circuitry. There are several ifs, buts and caveats to that which I am fully aware of but for the sake of simplicity it's pretty much correct.
    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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