YAMAHA A-S701 - tear-down, thoughts about the internals & few measurements

[Doodski]

If you play the same test with a signal, you will not be able to hear any noise difference, but your neighbors might come to ram in your door while shrieking hysterically, so in either case, it's audible.

But seriously, it's not. This feature is purely added because it is expected, not because it sounds much better. Maybe there was a point to it 50 or so years ago, but todays opamps are pretty much flawless. You can measure some difference, but are you able to hear it with music?

When I retailed Yamaha we had the RX series receivers with the direct switch button on them and we decided to do a test in the sound room and the result was that we could hear a difference with the direct switch engaged to the ON position. It was slightly more clear and sharp when the direct switch was engaged.

 

[trl]

If you play the same test with a signal, you will not be able to hear any noise difference, but your neighbors might come to ram in your door while shrieking hysterically, so in either case, it's audible.

But seriously, it's not. This feature is purely added because it is expected, not because it sounds much better. Maybe there was a point to it 50 or so years ago, but todays opamps are pretty much flawless. You can measure some difference, but are you able to hear it with music?

You may need to educate yourself a bit on this subject, although I'm pretty sure it has been explained on ASR what these features are actually doing:
- Pure Direct is bypassing the internal EQ, Loudness and Balance, hence the background noise gets a bit lowered
- CD Direct is bypassing the internal preamp completely (like Pure Direct from above) but is also using a dedicated analogue input with a lower internal gain.

Like I stated already, with Pure Direct or CD Direct pressed the background noise is noticeable lowered, although this can only be verified when the ear if very close to the tweeter or midrange drivers (preferable less than 0,5m). When playing test signals I'm not able to tell a difference between these settings, same when listening to the music (of course, if EQ/Balance/Loudness are to zero setting).

For example, other manufacturers like Naim are not even taking into account including EQ or Loudness in their amps, so in their case there's probably no need for adding a Pure or Direct feature.

For myself, having EQ, Balance and Loudness controls are perfect for watching movies or for general audio content, but for music I always use CD Direct.

 

[TheBatsEar]

It was slightly more clear and sharp when the direct switch was engaged

I suspect you say that just to harvest the ear caps, because they are nifty and you want to look sharp. I understand. That is why i added the blind test.

- Pure Direct is bypassing the internal EQ, Loudness and Balance, hence the background noise gets a bit lowered
- CD Direct is bypassing the internal preamp completely (like Pure Direct from above) but is also using a dedicated analogue input with a lower internal gain.

Yes, that is what the manual says and i agree that you can measure it.
I even agree that you can hear a difference in hiss, with the volume at 12 and your ear at the speaker grille.

You see, it's just that I highly doubt that anyone can reliably hear it sitting in a listening position while music is reproduced.

You may need to educate yourself a bit

I hole-hardedly agree, but allow me to play doubles advocate here for a moment.
For all intensive purposes I think you are wrong. In an age where false morals are a diamond dozen, true virtues are a blessing in the skies. We often put our false morality on a petal stool like a bunch of pre-Madonnas, but you all seem to be taking something very valuable for granite. So I ask of you to mustard up all the strength you can because it is a doggy dog world out there. Although there is some merit to what you are saying it seems like you have a huge ship on your shoulder.
In your argument you seem to throw everything in but the kids Nsync, and even though you are having a feel day with this I am here to bring you back into reality. I have a sick sense when it comes to these types of things. It is almost spooky, because I cannot turn a blonde eye to these glaring flaws in your rhetoric.
I have zero taller ants when it comes to people spouting out hate in the name of moral righteousness. You just need to remember what comes around is all around, and when supply and command fails you will be the first to go. Make my words, when you get down to brass stacks it doesn't take rocket appliances to get two birds stoned at once. It's clear who makes the pants in this relationship, and sometimes you just have to swallow your prize and accept the facts. You might have to come to this conclusion through denial and error but I swear on my mother's mating name that when you put the petal to the medal you will pass with flying carpets like it’s a peach of cake.

 

[Willem]

I would simply use the digital inputs and keep the tone controls etc.

 

[TheBatsEar]

I would simply use the digital inputs and keep the tone controls etc.

If you study the schematics you will see that, at some point, the digital signal turns analog, and gets injected into the source selector like any other signal. The tone controls are analog, so they are in the path for both digital and analog (unless you defeat them with the direct button of course).

BTW, if you really want to have the perfect sound with the A-S701, you sell it and buy the A-S700, because that has a slightly better THD+N. The DAC seems to make the 701 slighly worse.
In fact, forget that, get the R-S700 and hook up your external DAC to it's "Main In" (the R-S700 was the last device that has a Pre Out/Main In loop, not even the A-S1200 and up has a proper one) and do the volume changes in the DAC too. The amp section and power supply are the same as the ones in the A-S 700/701/801, as can be seen in this thread:

Inside Yamaha amps

Anyone interested in looking inside Yamaha amps? I have a bunch in my collection, most of them need repair, all of them have to be opened eventually for dusting. I'll start with some pictures i made inside a A-S1000 that i bought for 500€ in mint condition. This one weighs 25kg, it's a serious...

www.audiosciencereview.com

That way you even circumvent the volume knob, tone controls, source selector and their possible problems entirely.

Not that i think it will be audible with actual music playing.

 

[Willem]

I never tried, let alone under controlled conditions, but I would be very surprised if any of this would indeed be audible under normal listening conditions. The phono input might show something, but I have written off analogue sources ages ago anyway.
I bought my daughter an AS501 and it is a remarkabĺy good amplifier. You really have to get something like an RME Adi-2 Dac plus a beefy Hypex power amp to get something that may sound a bit better, particularly in a large room.

 

[Doodski]

I never tried, let alone on controlled conditipns, but I would be very surprised if any of this would indeed be audible under normal listening conditions. The phono input might show something, but I have written off analogue sources ages ago anyway.
I bought my daughter an AS501 and it is a remarkabĺy good amplifier. You really have to get something like an RME Adi-2 Dac plus a beefy Hypex power amp to get something that may sound a bit better, particularly in a large room.

Before I retailed Yamaha gear I retailed Technics, Fisher, Sanyo, Sony, Carver, JVC, Mitsubishi, Hitachi and some lesser brands and Yamaha was always a thorn in my side because customers wanted to inquire about Yamaha gear. So when I started retailing Yamaha gear I was very interested in the gear. I found out pretty quick that Yamaha offers pretty good value for the money spent. I quickly adjusted my sales pitch and went full on Yamaha for several years and it was a big success. I earned sales contest winnings every year from Yamaha and every year I had a new gratis amp from Yamaha and sold the old stuff.

 

[posvibes]

Yes, that is what the manual says and i agree that you can measure it.

I wasn't going to comment on this thread but due to unforeskin circumcised I thought "taller ants" was very good.

Carry on accordingly.

 

[trl]

I wasn't going to comment on this thread but due to unforeskin circumcised I thought "taller ants" was very good.

Carry on accordingly.

You do realize this was a copy-paste from Internet forums, right? It's his"Head-Fi" way of letting me know that he disagrees with me. It's pitty when I see ASR folks polluting theads with no-value comments, outside the subject as well.

However, Happy New Year to you all!

 

[posvibes]

You do realize this was a copy-paste from Internet forums, right?

Umm, no I didn't, I had no idea at all or that there was some prior historical dispute in play. I was just amused at the humorous use of language in the service of the topic. I wasn't supporting or not supporting the points made in @TheBatsEar 's post, just the amusing use of Lennonesque-isms.

 

[TheBatsEar]

Umm, no I didn't, I had no idea at all or that there was some prior historical dispute in play.

Neither did i. This and a two obscure German hifi forums are all i visit. Don't know much about the Head-Fi way either, but it must be a powerful accusation.

@trl Stop telling people they should educate themselves about trivial stuff and you wont get harmless banter in return.

 

[DSJR]

Does anyone have an old 596 or similar (ancestor of the current models) to see how different the input stage is 'on the bench?'

 

[Rosenbloom]

Today, I was told by a local dealer (I am based in the UK) that there is a “new version” of A-S701, and in the UK it will be provided in black color only. Has anyone heard of this “new version” of A-S701? I sought over the internet and found nothing about the so-called “new version”.

 

[TheBatsEar]

Ask your dealer for proof then. Should not be hard to deliver, if it's factual.

I haven't heard anything, but a MK2 with pre-out/main-in loop would be welcome, you could add external DSP/EQ.

 

[restorer-john]

Ask your dealer for proof then. Should not be hard to deliver, if it's factual.

Dealers are often advised by the importers of upcoming changes to the models coming into their countries and that is communicated usually direct from Japan with Yamaha.

That information is for dealers, not the public (it's none of their business) and is usually done many months out to allow retailers and stockists to clear old colours/models and claim rebates from Yamaha (where appropriate). Good customers get the inside information, especially where deals are to made that benefit both the retailer and the customer.

If anything, the A-S701 would likely get a new D/A converter with USB input is my guess. Otherwise much the same. It's being heavily discounted here too (about $320 off). It might be called an A-701 mk2 or an A-S702. Silver has been the poorer seller for Yamaha forever (except the 1970s) and they kill colours that don't sell enough units as they have to maintain a range in all colours.

My bet is a USB connection right here, like the 801 and a slight price increase.

 

[Rosenbloom]

Ask your dealer for proof then. Should not be hard to deliver, if it's factual.

I haven't heard anything, but a MK2 with pre-out/main-in loop would be welcome, you could add external DSP/EQ.

I did. The dealer said he had asked Yamaha UK for further details and would get back to me later.
The dealer said the new version is already available for purchase and Yamaha UK will update their website soon. But I checked all over the internet and found nothing about the new version, if it exists. Very strange.

 

[TheBatsEar]

Me when i learn that the 702 just gets bluetooth without LDAC.

 

[Rosenbloom]

Dealers are often advised by the importers of upcoming changes to the models coming into their countries and that is communicated usually direct from Japan with Yamaha.

That information is for dealers, not the public (it's none of their business) and is usually done many months out to allow retailers and stockists to clear old colours/models and claim rebates from Yamaha (where appropriate). Good customers get the inside information, especially where deals are to made that benefit both the retailer and the customer.

If anything, the A-S701 would likely get a new D/A converter with USB input is my guess. Otherwise much the same. It's being heavily discounted here too (about $320 off). It might be called an A-701 mk2 or an A-S702. Silver has been the poorer seller for Yamaha forever (except the 1970s) and they kill colours that don't sell enough units as they have to maintain a range in all colours.

My bet is a USB connection right here, like the 801 and a slight price increase.

View attachment 255451

Yup, my wishful thinking is an upgrade of the dac, adding usb input, AND an upgrade of the headphone output. Then I will buy one immediately.

 

[restorer-john]

Some dealers know about it...

 

[Rosenbloom]

What surprised me is the lack of information how this new version MK2 is different from the old one.