Yamaha Amplifiers - Pure Direct and CD Direct Amp - comparisons sought

Discussion in 'Audio Hardware' started by George P, Mar 18, 2019.

  1. George P

    George P Notable Member Thread Starter

    Location:
    NYC
    Although pretty happy with my A-S801, I have been thinking my system's sound was slightly dull on top and that the bass sounds less defined than I would prefer. This is the sound that I get using the CD Direct Amp function, which I have been using for the last 9 months. Over the last few months, I have been looking for ways to correct this, but haven't found a solution. I hadn't considered changing to Pure Direct because I thought that CD Direct Amp was the optimum way to listen to a CD player through a Yamaha amp.

    Today I started experimenting with the Pure Direct function. I did some brief comparisons with a few CDs and found that with CD Direct Amp I get a smoother sound, with a bit more bass and a bit less treble than what I get with the Pure Direct. The sound is rich and thick, but also muddy at times and again, sometimes slightly dull on top.

    Pure Direct, by comparison, seems to give me a tighter, better defined bass and a bit more treble (and/or clarity on top.) The overall sound is a bit thinner, but I can hear more detail. Reading the manual, the Pure Direct function seems to be more pure than CD Direct Amp, as it simply provides a direct path, bypassing the tone controls (bass/treble/balance/loudness.)

    CD Direct Amp does what Pure Direct does (stops power supply to the unnecessary circuit for CD playback), but also converts the input signal to the normal phase and reverse phase, and balance transfer to the electronic volume. The manual claims this will result in improved signal to noise ratio (pure direct boasts this as well), external noise canceling and reduced distortion.

    So, if I understand this correctly, CD Direct Amp processes the sound inputted, while Pure Direct does not.

    Has anyone else done any comparisons using these two functions on their Yamaha amp? If so, can you please report your findings? If not, can you compare some of your CDs, playing them through each of these functions and report back your findings? I am very curious to hear what other people come up with.
     
    mackeyse likes this.
  2. George P

    George P Notable Member Thread Starter

    Location:
    NYC
    I plan to do more extensive comparisons this week and will post my findings here. I'm hoping that more Yamaha amplifier owners will do the same.
     
    mackeyse likes this.
  3. George P

    George P Notable Member Thread Starter

    Location:
    NYC
    For those who might be wondering, CD Direct Amp is a function that Yamaha only includes in their A-S701 and A-S801 amps.
     
    mackeyse likes this.
  4. thetman

    thetman Forum Resident

    Location:
    earth
    will have to do some experimenting my own. I've had the 801 for about 4 months now- I have left it on pure direct for cd listening ( cd player via coax). I listen to two channel sacd through the cd inputs.
     
    George P likes this.
  5. George P

    George P Notable Member Thread Starter

    Location:
    NYC
    That would be great! I am anxious to hear other people's findings.

    I'm going to do some more comparing later today.
     
  6. Bananas&blow

    Bananas&blow It's just that demon life has got me in its sway

    Location:
    Pacific Beach, CA
    A-s801 with muddy bass? Shirly you jest. One of the great strengths to me of the 801 is the tight bass control. And the great neutral sound. I'll be damned if I can hear the difference between pure direct and with it off, but I put it on to make me think it sounds better. What speakers are you running with it? Where are they placed in the room? Are you running a sub also? Are the speakers on a desktop or poor stands. I suspect something else is muddying the bass.
     
    irender, bradleyc and Stanton56 like this.
  7. thetman

    thetman Forum Resident

    Location:
    earth
    I agree- bass is super tight, sounds excellent using the 801 with Forte III's. No muddiness
     
    bradleyc likes this.
  8. George P

    George P Notable Member Thread Starter

    Location:
    NYC
    Compare the CD Direct Amp and Pure Direct functions yet?
     
  9. thetman

    thetman Forum Resident

    Location:
    earth
    I haven't had a chance unfortunately. Hopefully by the end of the week sometimes. need to put some quiet time aside.
     
    George P likes this.
  10. harby

    harby Forum Resident

    Location:
    Portland, OR, USA
    "Pure Direct" is bypassing the sound processing, tone and loudness, etc. On other receivers, it would bypass the DSP completely, disabling bass management, and sometimes turn off the display.
    CD direct on this receiver, just for analog CD in, is also turning off the power supply for unneeded circuitry, such as the USB, digital, or phono pre.

    The result should be a lower noise floor, but if you can't hear any noise when putting your ear up to the tweeter, the further benefits would be minimal.
     
    Last edited: Mar 20, 2019
    thxphotog likes this.
  11. StimpyWan

    StimpyWan Forum Resident

    While not an integrated amp, my Yamaha RX-A3030 has Pure Direct, Straight, and Stereo options. They do make a difference. I just received Steve Hackett's latest release on CD, and I'll test it out this weekend. I also bought a new copy of Hackett's Defector. That one I'm much more familiar with. It'll make for an interesting test disc as well.
     
    4xoddic and George P like this.
  12. George P

    George P Notable Member Thread Starter

    Location:
    NYC
    Have you guys had a chance to do these comparisons yet?

    I recommend using a dark mastering with full bass for your comparisons. I think these masterings show the differences best.

    I tried again today, using the AF Phil Collins No Jacket Required CD. The sound using the CD Direct Amp function is quite thick in the bass and slightly dark. When I switch to Pure Direct, the bass thins out a bit (just enough to sound "right") and the top seems more transparent.
     
    Spokeless likes this.
  13. thetman

    thetman Forum Resident

    Location:
    earth
    sorry for the long delay. life has been busy lately for sure. but I have to agree with you . now I am not saying these are huge differences. but yes in pure direct mode things seem to open up a bit, "more transparent" as you say. not huge but yes a bit more and bass seems to be a bit tighter.
    tried swapping out optical and digital coax cables too. didn't hear much difference between the two going into the 801 using its dac.

    i also fooled around with the tone controls ( pure direct off) and sometimes it seems to help out with some cds I play ( overly bright cds for example). I am able to tone it down a bit to make a more enjoyable listening session. So sometimes "not" using pure direct will have its advantages as well I think. its nice to have that option.

    For the most part I leave it on pure direct mode most of the time. Using a digital coax cable from cd player to 801.
    for sacds I still have the oppo 103 connected using analog outputs connected to cd inputs on the 801.
     
    fogalu and George P like this.
  14. George P

    George P Notable Member Thread Starter

    Location:
    NYC
    Anyone else compare these settings (1. Pure Direct, 2. CD Direct and 3. both of these disabled) on their Yamaha Amps?
     
  15. Fedot L

    Fedot L Forum Resident

    There is! The solution that lets me avoid this kind of troubles for many years since my first system.

    Never use “CD Direct”, “Pure Direct” and similar.

    The only way to manage the spectrum of your system to your taste, is the obligatory reasonable use of graphic equalizer(s). Not any, but at least 10-bands, with their lowest slider at not higher than 31 Hz, THD desirable ≤0.02%, S/N desirable 90 dB or higher.

    Necessary first of all for a possible correction, within your powers, of the room’s reaction, then of the loudspeakers’ frequency diagram, then of possible spectral defects of sound material.

    This may need even two EQs. In my case, one suffices.

    All I exposed lets me have the highest quality sound I want completely. From very high quality sound material, sure.
     
    fogalu likes this.
  16. George P

    George P Notable Member Thread Starter

    Location:
    NYC
    Thanks for sharing that.

    Anyone else avoid the use of Pure Direct and the like when using their amplifier?
     
  17. George P

    George P Notable Member Thread Starter

    Location:
    NYC
    I think I need to get out of the mindset that just one setting on my amp will or (should) be sufficient. Pure Direct, CD Direct Amp, both of these disabled but tone controls flat or using tone controls are all options available to me. When my meal arrives when I go out to eat and it needs more seasoning, I don't send it back. I add a bit of salt or pepper or whatever and then enjoy my meal. I'd like to approach my music listening in the same way.
     
    riddlemay, Press and fogalu like this.
  18. thetman

    thetman Forum Resident

    Location:
    earth
    while I usually do leave on pure direct- having the tone controls (pure direct off) does help on certain cds. Some are a bit bright- lately I have been going through my collection re-discovering some original 80's cds. I was blown away how good many sounded compared to some of todays pressings. Others, while sounding good seemed to be a bit too laid back. the tone controsl help me liven them up a bit. I like having the option of doing either or. So basically I guess there is no set it and forget it setting.
     
    fogalu and George P like this.
  19. SMc

    SMc Forum Resident

    Location:
    Austin TX
    From the 6moons review: On the CD input, CD Direct bypasses the tone and balance controls. Pure Direct bypasses the buffer amp, tone, loudness and balance controls for the most minimalist path.

    Could be similar to the difference between a preamp and a passive "preamp."
     
    Tim 2 likes this.
  20. George P

    George P Notable Member Thread Starter

    Location:
    NYC
    The 6moons review isn't exactly right. Both "CD Direct Amp" and "Pure Direct" bypass the tone, balance and loudness controls. The difference between them is that CD Direct Amp also "stops power supply to the unnecessary circuit for CD playback, converts the input signal to the normal phase and the reverse phase, and balance transfer to the electronic volume."

    The above information comes directly out of the A-S801 manual.
     
    Last edited: May 22, 2019
    SMc likes this.
  21. L5730

    L5730 Forum Resident

    AS-700 here, and previously a mid 90's AX-470.
    Used with matching CD-S700 CD player.

    Pure Direct:
    Bypasses (Balance?), Loudness control and Bass/Treble controls.
    Provides a shorter signal path from input source selector to pre-amplifier circuit.
    To us it improves tightness and directness of the sound. It's not a massive difference, but it is audible when someone else switches and another listens with eyes closed (not a proper blind test by any means).
    Unless we have need for the tone controls (we don't, we can use DSP in software) or the loudness control, Pure Direct is used for anything but CD input.

    CD Direct Amp:
    Bypasses , Loudness control, Bass/Treble controls and input selector and Pure Direct control.
    Provides the shortest possible signal path for the CD input to pre-amplifier circuit*.
    * there seems to also be an Op-Amp circuit in addition when this input is used - makes me think it is better matched for input impedance for CD players typical output impedance.
    To us, comparing this over Pure Direct (which can still be left engaged, as it's just superseded/bypassed as well) there is a slight volume increase, less than half a dB though. This makes everything sound fuller and cleaner/tighter. However, because it is only usable for whatever source is connected to the CD Input on the back, it is of limited use. In reality I think without the volume change from the little circuit, I doubt there is much actual change at all - small level changes play tricks on our hearing!

    If just using a CD Player, we leave CD Direct Amp engaged. If we run a USB DAC from laptop, it's connected to Line 1, we use Pure Direct.

    6moons audio reviews: Yamaha A-S700 & CD-S700
    Right behind the CD input sits an op amp which Yamaha's marketing turned into CD Direct Amplification to signify a discrete gain stage. This is said to stabilize the signal prior to entering the main circuitry while maximizing noise and dynamic performance.​

    .
     
    Timothy Fiacco, thetman and George P like this.
  22. jeffmackwood

    jeffmackwood Forum Resident

    Location:
    Ottawa
    I've had similarly-labeled functions on a few devices over the years and never noticed an audible difference when it was engaged. It's therefore not a feature that I would specifically look for in a future acquisition.

    Assuming that the output level remains identical whether engaged or not, and given near-instantaneous switching, it is therefore one feature that is quite easy to A/B test and detect a difference, should there be one.

    Jeff
     
  23. George P

    George P Notable Member Thread Starter

    Location:
    NYC
    Thanks for all that, my friend!
     
  24. wwaldmanfan

    wwaldmanfan Born In The 50's

    Location:
    NJ
    From my Yamaha AX-592 manual. Do I hear a difference? Not enough for it to matter. It's self-evident to use whichever setting sounds best to you, and not worry about it.
    [​IMG]
    [​IMG]
     
  25. craschowder

    craschowder New Member

    Location:
    Phoenix, AZ
    When using the CD-S300 CD player in it's own pure direct mode the difference when switching between the Pure Direct and CD Direct on my A-S701 is really night and day.CD direct adds much clarity and air. I am quite surprised that some here seem to hear very little difference. Perhaps some speakers are not sensitive enough to reproduce the change?

    The improvement I hear right away is on symbols. The clarity improves immediately and it translates down to the rest of the program materiel. Separation is improved as well. It is a great feature!
     

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