Yamaha A-S801 Boost or Roll-Off?

[<eargiant]

So I've been wondering about this ever since I got this unit a while back. What is it in the signal path that creates such a noticeable difference between having the Pure Direct ON vs OFF (even with all the tone controls set to flat)? I'm using FLAC files fed to the built-in USB connection and internal DAC.

I've always felt that the highs are either somewhat boosted in pure direct or slightly rolled off in the normal mode? Which one is it? Are they somehow "juicing" one or the other? If not, what is the impeding factor in the path with the tone controls (set to flat)? What parts are in the OFF path that might be causing this clear difference? Has anyone looked at the schematic?

 

[AcuDefTechGuy]

I’m guessing the speakers and room acoustics are causing the boosted treble, not the Yamaha Amp.

Remember, the B&W 805D has a +7dB treble boost in the treble.

Some rooms may magnify the boost, and some rooms may attenuate the boost.

Or the Yamaha amp may have an issue and you just need an AVR, AVR, AVR. Just joking!

 

[lovinthehd]

Pg 12 of the manual:
When the PURE DIRECT func
tion is on, noise can be
reduced by bypassing the circ
uit that the audio input
signal is not using and stopping the power supply to the
circuit.
Therefore, in all input sources, you can enjoy music
playback in straight and high quality sound.
The indicator above the PU
RE DIRECT button lights up
when this function is turned on.

 

[<eargiant]

I’m guessing the speakers and room acoustics are causing the boosted treble, not the Yamaha Amp.

Remember, the B&W 805D has a +7dB treble boost in the treble.

Some rooms may magnify the boost, and some rooms may attenuate the boost.

Or the Yamaha amp may have an issue and you just need an AVR, AVR, AVR. Just joking!

I'm not using the 805D2s on the Yamaha. Different set of speakers (not the CM5s either). Also, the room doesn't change when I flip the switch so it's not the room. I can also hear it on three headphones I own (HD650, AKG7XX and ATH- M50). Same amp, same source, different transducers- only difference is the Direct being ON or OFF. Regardless of how the highs sound, they change in Direct mode.

Pg 12 of the manual:
When the PURE DIRECT func
tion is on, noise can be
reduced by bypassing the circ
uit that the audio input
signal is not using and stopping the power supply to the
circuit.
Therefore, in all input sources, you can enjoy music
playback in straight and high quality sound.
The indicator above the PU
RE DIRECT button lights up
when this function is turned on.

Thanks, I do get the concept and in theory- how it works, but I've never noticed such a difference on other amps with a "Direct" switch. It really almost sounds like something else is going on.

 

[lovinthehd]

Measure the difference.

 

[<eargiant]

Measure the difference.

I've been thinking about that. Can you guys help me get started? What equipment would I need?

I would think it would have to be a very sensitive mic. Regardless, if I can measure a difference how will I be able to determine the cause?

 

[<eargiant]

Hate to use the old "my wife heard it" but I just did a quick switch for her between the two on a song she loves (yes I know, not a true blind test but she didn't know which was which) and I asked if she could hear a difference. Instantaneously she said one sounded "louder" and "clearer"... it was the Direct mode.

What is going on here?

 

[PENG]

Hate to use the old "my wife heard it" but I just did a quick switch for her between the two on a song she loves (yes I know, not a true blind test but she didn't know which was which) and I asked if she could hear a difference. Instantaneously she said one sounded "louder" and "clearer"... it was the Direct mode.

What is going on here?

She may be right about one being louder. If it bypass the stage for tone control, there could be a slight different in the overall gain. If you don't have the expensive AP, one simple check is to measure the output voltage to see if it is a little higher when pure direct is pressed. You still need a good digital meter such as the Fluke 87-V that has the required accuracy and bandwidth.

A good alternative is to run REW sweep test using a good quality mic. That will definitely reveal an audible difference. In fact I do use it to compare my amps, using the same speakers and mic position.

 

[lovinthehd]

If you want to measure with a mic and have a laptop, a usb mic like the Umik-1 from miniDSP or the UMM-6 from Dayton/Parts-Express are good basic measurement mics. REW software here https://www.roomeqwizard.com/.

Small differences in level due to the different circuitry does make sense....

 

[AcuDefTechGuy]

Hate to use the old "my wife heard it" but I just did a quick switch for her between the two on a song she loves (yes I know, not a true blind test but she didn't know which was which) and I asked if she could hear a difference. Instantaneously she said one sounded "louder" and "clearer"... it was the Direct mode.

What is going on here?

It seems like there is some kind of DSP that is adversely affecting the sound when not in Direct Mode.

The question is, when Direct Mode is off, is the amp in Stereo Mode or some other Mode by default?

In all the Denon AVRs I’ve used, the difference between Pure Direct vs Stereo isn’t that pronounced.

When Direct Mode is turned off, I get Stereo Mode by default unless I manually change the mode to something else.

There is definitely a significant difference between Direct Mode and some other DSP modes.

 

[William Lemmerhirt]

It seems like there is some kind of DSP that is adversely affecting the sound when not in Direct Mode.

The question is, when Direct Mode is off, is the amp in Stereo Mode or some other Mode by default?

In all the Denon AVRs I’ve used, the difference between Pure Direct vs Stereo isn’t that pronounced.

When Direct Mode is turned off, I get Stereo Mode by default unless I manually change the mode to something else.

There is definitely a significant difference between Direct Mode and some other DSP modes.

This is where I was going too. I don’t know if this unit has ypao but if it is like the denon as you referenced, then it should sound different. I might need more coffee though so go easy on me if I’m on the wrong road...

Yep. Back to bed for me. Just looked at this at Yamaha.com...

 

[KEW]

The first thing I would do is use pink noise with SLP meter to check that the levels are matched.
The explanation that the tone control circuits. etc somehow effect the gain structure resulting in a different level seems like the most reasonable explanation of the info you have given us ... and it is also the easiest to verify!

 

[TheWarrior]

She may be right about one being louder. If it bypass the stage for tone control, there could be a slight different in the overall gain.

My 3060 needs to be turned up a bit when switched to Pure Direct.

That said, I greatly prefer the Pure Direct for critical listening of music.

 

[PENG]

My 3060 needs to be turned up a bit when switched to Pure Direct.

That said, I greatly prefer the Pure Direct for critical listening of music.

I had a Sony ES receive once and I also thought pure direct sound better but it turned out it was just louder. I used to prefer pure direct too but not since I started using REW because now I know the importance of EQ, whether manual or auto. The slightly improved transparency due to pure direct simply cannot compensate for not being able to EQ. Now if you are in a near perfect room then definitely pure direct is the way to go. Speakers that are less sensitive to room acoustic imperfections surely would help too.

 

[TheWarrior]

I had a Sony ES receive once and I also thought pure direct sound better but it turned out it was just louder. I used to prefer pure direct too but not since I started using REW because now I know the importance of EQ, whether manual or auto. The slightly improved transparency due to pure direct simply cannot compensate for not being able to EQ. Now if you are in a near perfect room then definitely pure direct is the way to go. Speakers that are less sensitive to room acoustic imperfections surely would help too.

The only EQ I use is in my subs!

But don't forget, due to wavelength, there are effectively two sound fields in any room. Bass has to be treated differently, and as the sound transitions to be dominated by reflections, the basic furnishings of fluffy pillows and bookshelves all can serve to keep balanced sound at all listening locations.

I used to beat myself up about 'only' having a big and open living room for an HT. While I still fantasize about the 'hidden room behind a bookshelf' concept, learning more about dealing with rooms as a part of the play back system has proven that I can have it just as good in my less than ideal space!

 

[PENG]

The only EQ I use is in my subs!

But don't forget, due to wavelength, there are effectively two sound fields in any room. Bass has to be treated differently, and as the sound transitions to be dominated by reflections, the basic furnishings of fluffy pillows and bookshelves all can serve to keep balanced sound at all listening locations.

I used to beat myself up about 'only' having a big and open living room for an HT. While I still fantasize about the 'hidden room behind a bookshelf' concept, learning more about dealing with rooms as a part of the play back system has proven that I can have it just as good in my less than ideal space!

I don't know how good your room is, but try using REW to plot the left and right speaker individually and I bet you will find that without EQ your sound stage in theory will not be good. Some musical instrument will be hard to locate as it would move side way all the time from moment to moment.

Problem is, even with perfect EQ, you still have to sit in one spot and don't even cough. So much for people who though amps are so critical..

 

[TheWarrior]

I don't know how good your room is, but try using REW to plot the left and right speaker individually and I bet you will find that without EQ your sound stage in theory will not be good. Some musical instrument will be hard to locate as it would move side way all the time from moment to moment.

Problem is, even with perfect EQ, you still have to sit in one spot and don't even cough. So much for people who though amps are so critical..

My biggest issue right now is the need to lower the noise floor in order to increase dynamic range. Sealing the crawlspace, and getting all the exterior door frames properly insulated. Might double up some of the drywall as well...

I have a whole couch that sounds great, so no worries there! And yeah, amps/damping factor issues brought up around here are mostly amusing!

 

[PENG]

My biggest issue right now is the need to lower the noise floor in order to increase dynamic range. Sealing the crawlspace, and getting all the exterior door frames properly insulated. Might double up some of the drywall as well...

I have a whole couch that sounds great, so no worries there! And yeah, amps/damping factor issues brought up around here are mostly amusing!

If I have a couch like that I won't bother with any EQ!!

Seriously, well design speakers can alleviate room issues in general, but only to a point, but enough for those speakers to be preferred by more people according to studies.

 

[<eargiant]

If you want to measure with a mic and have a laptop, a usb mic like the Umik-1 from miniDSP or the UMM-6 from Dayton/Parts-Express are good basic measurement mics. REW software here https://www.roomeqwizard.com/.

Small differences in level due to the different circuitry does make sense....

Thanks. I'm going to order the Umik-1. Is this the legit site (best way to order)?

https://www.minidsp.com/products/acoustic-measurement/umik-1

 

[PENG]

Thanks. I'm going to order the Umik-1. Is this the legit site (best way to order)?

https://www.minidsp.com/products/acoustic-measurement/umik-1

That's the site I ordered mine from.