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  1. Old Comment
    fas42's Avatar

    How good can the sound get?

    As part of the picture, during the cycle of extracting the maximum from recordings there can be an awkward stage when it becomes easy to pick when pieces are spliced as a separate take; not because of the normal sort of reasons, but because the recording electronics hadn't been brought to the same stage of warm-up each time - this is my guesstimate. This is most obvious on classical recordings, when say, the violin tone suddenly drops in tonal quality for a section, and then just as suddenly picks up again - some of the most recent classical efforts are quite atrocious in this regard. Quite disconcerting to listen to, even if you know what's going on ...

    What to do about it? My suggestion is to push the quality of the replay system to even higher levels, so that subjectively these events don't register as distinctly as they otherwise do; the ear/brain "rolls over" the divide, takes it in with less awareness being consciously triggered that there was a 'glitch'.
    Posted Today at 01:27 AM by fas42 fas42 is online now
  2. Old Comment
    fas42's Avatar

    Fix it time for PC monitor speakers

    Audio never loses its ability to surprise - and enchant me ... I was inspired to try another bit of tweaking, because a classical piece, a no-name recording of Brahms Trios, made it clear that interference effects from other electricals plugged in were still a very significant factor. So, resorted to nothing more than a bit more of reorganising where the essentials were plugged into the mains - and, very nice benefits: a mid 80's DG recording of Prokofiev and Ravel violin and piano sonatas projects lovely tone and air - the big space around the instruments comes through beautifully ...
    Posted Today at 12:59 AM by fas42 fas42 is online now
    Updated Today at 01:04 AM by fas42
  3. Old Comment

    Voltage regulators for (line level?) audio: The GeminiPS

    Replace the Zener with a series string of a 8.2V Zener and a red LED for 2x better temperature drift. Using two 4.7V Zeners and a 1N4004 in series is even 7x better; that is only 0.2V output drift from 30°C to 100°C (simulated).
    Posted Yesterday at 11:14 AM by Preamp Preamp is offline
  4. Old Comment
    Posted 22nd April 2014 at 11:18 AM by jan.didden jan.didden is offline
    Updated 22nd April 2014 at 11:21 AM by jan.didden
  5. Old Comment

    Superregs for your line-level projects

    Thank you Jan!
    : )

    Posted 20th April 2014 at 06:56 PM by FormosaWest FormosaWest is offline
  6. Old Comment
    jan.didden's Avatar

    Superregs for your line-level projects

    Andrew, the key thing you need to remember is that in actual operation, the opamp inputs are at the same level.So, if you have a reference of 6.9V at the + input, you want a 12V output, then the resistors on the -input have to be sized to divide down the 12V output to 6.9V.
    An easy way out: make the lower resistor 6.9V, then the top resistor, which has 12-6.9=5.1V across it should be 5.1k.

    A more general solution: Vout/Vref=Rtotal/Rbottom.
    So if you decide to make Rbottom = 1k, then Rtotal = (Vout/Vref) in kohm. Subtract 1k from Rtotal and you have Rtop.

    Does that help?

    Posted 20th April 2014 at 10:42 AM by jan.didden jan.didden is offline
    Updated 20th April 2014 at 10:45 AM by jan.didden
  7. Old Comment

    Superregs for your line-level projects

    Hello! Ive just read your build-guide. I have a question please, before i order this board. how do we calculate the voltage divider values for R6 and R7, R13 and R14 to achieve a given output voltage.. for example, i will require +/-12.0v for one project. Can you please explain and provide examples? I dont want to make any false or erroneous assumptions.

    Posted 19th April 2014 at 08:12 PM by FormosaWest FormosaWest is offline
    Updated 19th April 2014 at 08:16 PM by FormosaWest
  8. Old Comment

    PSU for High end audio without electrolytic capacitors

    Hi Nazar!

    What is the value of C3 and C7?

    Posted 19th April 2014 at 02:09 PM by flyboi flyboi is online now
  9. Old Comment
    fas42's Avatar

    Fix it time for PC monitor speakers

    Worth repeating, yet again, that the mediation music CDs are quite brilliant at pinpointing the SQ - one's subjective involvement with these lives and dies by the harmonic quality of very slowly building and decaying, pure and frequently very high frequency, tones, sound envelopes; if these are not exactly right the "music" is extremely forgettable, totally bland ...
    Posted 19th April 2014 at 02:18 AM by fas42 fas42 is online now
  10. Old Comment
    fas42's Avatar

    How good can the sound get?

    Obviously, I am a little bit inspired, ...

    I was just doing a bit of forum surfing, and found references to the dartZeel 458 power amplifier, which is viciously expensive for the levels of THD it produces, the latter can easily be beaten by a cheap chip amp in PC speakers, . However, it does pump out a lot of power, which helps things .

    Anyway, the Stereophile review of the unit mentions the playing of an LP of Paul Simon's Graceland, which reminded me of what I heard years ago when I was fiddling, and used this album on CD quite a bit for assessment:

    In "Diamonds on the Soles of Her Shoes," Ladysmith Black Mambazo's opening chant, split between the channels, attained a hair-raising level of transparency and three-dimensionality, while the drum thwack that introduces the melody exploded from the left channel with alarming power and textural suppleness. As the "ta-na-nas" faded out at the end, everyone who sat and listened, from manufacturers to friends to John Atkinson, and without exception, exclaimed, "Wow!"
    Now, that is a good description of how that track should come across - and if it doesn't, then the system is not up to scratch. The recorded content is there, in the recording to produce the subjective experiences described ... it's up to the playback system to do its job properly, to reveal all that is in the recording.
    Posted 12th April 2014 at 05:18 AM by fas42 fas42 is online now
  11. Old Comment
    fas42's Avatar

    Fix it time for PC monitor speakers

    A thought - the chip amp powering these is a nothing thing, on just a rectangle of aluminium as a heat sink, only capable of a few watts per channel at reasonable distortion spec's, yet the subjective impact is far, far more than this would imply. Yesterday, running highly compressed, dense modern rock you could easily hear the limitations of the miniscule power supply doing its best, yet really only the major problem was that the sparkle of the cymbals, etc, was steadily lost and squashed as the volume was pushed - it was capable otherwise of clean, "deafening" volumes, that would start my ears ringing if I sat too close for a decent period.

    It also has that telling property of not changing its character as the volume drops - going from a reasonable max - some obvious soft clipping - down to the lowest that the digital volume would do, in its coarse decrements - the tonality of the sound doesn't significantly alter - the same intrinsic 'bite' of the recorded sound comes through ...
    Posted 11th April 2014 at 10:44 PM by fas42 fas42 is online now
  12. Old Comment

    Rebuilding a Hafler DH200 Part 1

    This was helpful,I have a very stock board (other than recap,and repair(no mods)and it was great to see a original pc 6 to compare to.
    Posted 10th April 2014 at 04:13 PM by KTnC KTnC is offline
  13. Old Comment

    Best source for TX2575 Naked Z-Foil Resistor

    Texas Components

    Yes, I agree, Arbie Lopez from Texas Components I S the best adress worldwide to buy world class resistors. And, what also counts: If you have special wishes, they can make things possible you wouldn´t think about... and thank you for the trim pot hint...
    Posted 8th April 2014 at 04:38 PM by Scheff Scheff is offline
  14. Old Comment

    Sapphire Headphone Amplifier rev. 2.0

    Hi RJM,

    Just wanted to point out that using these ltspice models from Cordell you can simulate your Sapphire buffers with BD139/BD140. The distorsions are a bit higher by the way and quite different with the third order becoming dominant. Here's a look:
    Click the image to open in full size.
    Posted 8th April 2014 at 08:46 AM by SunRa SunRa is offline
  15. Old Comment
    fas42's Avatar

    Fix it time for PC monitor speakers

    Some interesting behaviour occurring, timing is everything ...

    In the course of trying something, I fed near full level 15kHz sine waves into the speakers - the correct tone was certainly there, but very obvious were some pretty loud artifacts, way down in the midrange. Even more interesting, a particular "note" would appear at precisely a certain volume, above and below that setting that artifact disappeared.

    So, was this the speakers/amplifier, or the DAC/source misbehaving? Easy to test, pull the power on the speaker setup, and leave the player running at full volume - previous experience demonstrating that warm-up solved many things ...

    And, somewhat later, try powering up the speakers again - immediately, quite a bit better, and that peculiar level dependent artifact was gone. This demonstrates quite clearly that electronic misbehaviour in areas directly relating to the DAC can very much be part of poor sound ...
    Posted 8th April 2014 at 06:01 AM by fas42 fas42 is online now
    Updated 8th April 2014 at 06:04 AM by fas42
  16. Old Comment
    fas42's Avatar

    One Farad capacitor array

    Yes, once in the single digit or so milliohm range, everything starts to matter - how much copper, for what distance, is being used to pass current really starts to be relevant ...
    Posted 8th April 2014 at 01:48 AM by fas42 fas42 is online now
  17. Old Comment
    rjm's Avatar

    Voltage Regulators for Line Level Audio. Part IX : Two Transistor Series Regulator

    Thanks for the tip.

    To plot V(vout)/I(I1), click "add traces" on the plot menu, and type the expression in the blank line at the bottom of the dialog box. Then change the axis to linear as Calvin says above.

    Since the small signal current I(I1) is set to "1" in the example files, however, dividing though by the current does not change the numerical answer. I agree its more comforting to see it displayed in the right units though.
    Posted 7th April 2014 at 07:55 AM by rjm rjm is offline
  18. Old Comment

    One Farad capacitor array

    Good point - but still charging time is an issue if I wanted to turn this into a reproducable design. My customers aren't going to want to wait hours for sound to come out, powering from cold.

    I'll go step by step and see what supercaps bring to the party, if anything. I don't yet know for example how low in frequency the low impedance needs to go. For sure supercaps are major overkill in terms of going several octaves below 50Hz with their impedance.
    Posted 4th April 2014 at 11:31 PM by abraxalito abraxalito is offline
  19. Old Comment
    fas42's Avatar

    One Farad capacitor array

    Just to check things out, no need to go to 5.4V charge - at the worst the actual values may be say 2F and 3F, just charge up to 4V, hence a safety margin ...
    Posted 4th April 2014 at 10:25 PM by fas42 fas42 is online now
    Updated 4th April 2014 at 11:48 PM by fas42
  20. Old Comment

    One Farad capacitor array

    Yeah except charge balancing is a bit of a pig with two in series. LT makes a nice chip to do it, but its easier to begin with to go for a single one and see how it pans out. I know there are major sized ones available, but charging time becomes an issue and those hell-for-leather ones have terminals at opposite ends, not well suited to DAC chips...
    Posted 4th April 2014 at 12:05 AM by abraxalito abraxalito is offline
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