Why does Yamaha "Pure Direct" switch sound better than flat controls?

I bought an old Yamaha RX-570 yesterday, and one of its features is a "Pure Direct" switch. When engaged, this control "bypasses the BASS, TREBLE, BALANCE, and LOUDNESS controls, eliminating any alteration to the audio signal".

I normally run all of these controls flat anyway, but the "Pure Direct" setting definitely sounds better. Is this just a placebo effect, or is there something electro-acoustical happening here?

 

Normally, home-theater receivers run incoming analog signals through the ADC and then through the DAC. This can lead to degradation of the signal. The Pure Direct mode bypasses these unnecessary conversions, thereby preserving signal quality.

 

Yup, probably an all analog signal path. No cheap converters altering the sound.

 

With my Yamaha, when the Pure Direct switch is not used, the tone controls add a little ripple to the bass and treble even if centered on "0". I used CoolEdit to see just how far off the frequency response was and it wasn't much but even with tweaking the dials I couldn't perfectly flatten out the response.

 

Most quality-sound-loving people play their amps in 'Direct' mode. As has been said here, it degrades the sound less. Even if the tone controls are flat the signal is going through them. It only skips that part of the circuitry in 'Direct' mode.

 

Keith,

This is a two channel receiver, not a surround model.

Yeah, it shortens the signal path by not passing through these controls, thus cleaner sound.

 

Chops out tone controls and any 'loudness' circuitry if fitted.
Some Technics amps of the 80's had CD direct which remove the input switching too - my dad had one. I use my Rotel integrated amp with tone controls switched out most of the time as it's unnecessary on well mastered program.

Candy

 

Heh, I just pulled out an old RX-570 from the basement and am using it as a phono preamp. These old dinosaurs are built to last

 

To make handling input signals easier, many modern receivers/processors - stereo or surround - convert everything to a digital format.

But to confuse things, there are chips that can handle signals in their original analog form, but are *controlled* digitally by the receiver's microprocessor to more easily route these analog signals through the various circuit boards. So basically these are non-moving switches made with bits of silicon, with the advantage that they don't get dirty (which can cause distortion), are very long-lived & are much cheaper than an equal-quality mechanical switch.

Analog/digital hybrid systems are also used for many receivers' volume control systems.

 

My Marantz SR4320, which is only about 2 years old, has this feature. It is a 2 channel receiver.

I have found that the sound really depends on the mastering of the source. Some CD's sound great through the direct mode, others need the coloring of the tone controls. For example, the Living Stereo SACD's sound wonderful through the direct mode. Some of my punk or classic rock like the Stooges work better with with a few adjustments.

Its a neat feature that is fun to tinker with.

 

Even on my preamps, it is impossible to flatten out the signal even if the controls are at the "0" mark (centered). I notice a difference when I engage the tone controls.

 

---this receiver has been my main source of a/v power for like ten years now, maybe more...i run two other components from its power supply as well...i haven't tinkered with the pure direct switch in years, it's been OFF all this time, because i like "flat" too, but after reading these posts, well maybe an adjustment would be interesting...i'll have to switch it on and hear how it sounds...the unit does have an input knob "short" though, although it's always been able to be remedied with a few back and forth turns...i think i paid a little more than 400 dollars for it back in the day, so it's served me well through the years...i have my other components, CE595 and Pioneer DV-353, plugged directly into this unit----

 

While I can understand the distortion part but some of us have less than desirable acoustical rooms and need tone controls. Additionally, some speakers need more tuning than others to sound right.

Age also plays a big part as the HF part is the first to go.

I do use my Yamaha in Pure Direct as times but bass is lacking.

 

IMO, it is not necessarily whether the eq goes flat in a neutral position or not, though that is obviously important. The problem is that even with the controls in the flat position you are usually going through at least a few active sections of electronics which will often lessen transparency. And this is with your basic shelving equalization. If you have multiband graphic or parametric equalization there can be even more complex electronics to pass through.

 

Please delete. Slow forum led to double post.

 

Does anybody know if my Marantz SR 7000 (AV) converts to digital all analogue incoming signals? The problem with my receiver is that I loose bass management when Source Direct is engaged so my subwoofer is useless and my small B&W 601 speakers are very short on bass. What would be the best option for playing vinyl?