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

[Bernard23]

Thank you so much for this, I never ceased to be amazed by our membership. If I'm reading this correctly, it seem that the phono output section is somewhat average. Would it be a good idea to use a separate phono preamp and just run it to line in?

That's what I'm going to try, before returning the AT VM95ML I just bought. I'm not convinced about the phono stage, no evidence, just a hunch. I've got a vintage Cambridge Audio 540p
Otherwise I'm happy to report that 24 hours later and several hours use, there is no burn in whatsoever, even my ears. Sounds the same this evening as yesterday, thankfully; I am always a little alarmed that I'd be the first to discover burnout with a brand new piece of equipment.

 

[TheBatsEar]

I am always a little alarmed that I'd be the first to discover burnout with a brand new piece of equipment.

Are you talking about a device failure like in some part blowing up?
It's most likely this happens if it's new (early infant mortality failure rates), then it lowers over years and eventually rises again (wear failure rates). A highly interesting topic:

Burn-in - Wikipedia

en.wikipedia.org

And the causes for failures are as fascinating i think:

Failure of electronic components - Wikipedia

en.wikipedia.org

 

[Bernard23]

Are you talking about a device failure like in some part blowing up?
It's most likely this happens if it's new (early infant mortality failure rates), then it lowers over years and eventually rises again (wear failure rates). A highly interesting topic:

Burn-in - Wikipedia

en.wikipedia.org

And the causes for failures are as fascinating i think:

Failure of electronic components - Wikipedia

en.wikipedia.org

No, I was being ironic, poor attempt at humour. Burnout is where you believe that the sound quality degrades over the initial couple of weeks ownership.
Failure of electronic components (as in the circuit boards not the individual caps, resistors etc) is an area I work with in my day job. Investigating failure modes related to harsh environmental conditions giving rise to SIR and CAF failures. PD is another interesting area, especially when you start changing atmospheric pressure as well as humidity and condensation. It's associated with automotive and aerospace parts though, not consumer electronics.

 

[Bernard23]

Now that you have found your way to the variable loudness side of things, it's time for new furniture indeed:

I have two sets, one for 40€, one for 70€. I assembled them to have 4 layers each and they are on rollers to easily move them so i can reach the back:
View attachment 261004
View attachment 261005
I would guess there are about 60 to 70kg hardware in it. I think it can hold 30kg per layer.
Ten out of ten, would buy again.

I am struggling to find a replacement for my ancient pine cabinet, which is about 5cms to shallow, so the yamaha's nose is poking out of the front. It won't do, and I can't find anything at a sensible price that would work. Where did you get your from, and what is the approx width, as I've not got a lot of space to play with....

 

[ZolaIII]

No, I was being ironic, poor attempt at humour. Burnout is where you believe that the sound quality degrades over the initial couple of weeks ownership.
Failure of electronic components (as in the circuit boards not the individual caps, resistors etc) is an area I work with in my day job. Investigating failure modes related to harsh environmental conditions giving rise to SIR and CAF failures. PD is another interesting area, especially when you start changing atmospheric pressure as well as humidity and condensation. It's associated with automotive and aerospace parts though, not consumer electronics.

Now I sense diffusity. Some mechanical parts on some speakers do need some time to losen up a bit. Failure rate for electronic is as it always been first month of use and weak parts estimated life time not counting in abuse of course. Perfecting a design goes up to squishing out anomalies and some designs are more complex to a point of being too complex especially when it comes to particular ADSP areas complex wide architectures and cetera on the other hand FPGA's are also advancing. Had a soft spot for black boxes when I whose young tho ended up as a profesor of something entirely different.
Regarding furniture that's a tough one. See more compact TV stands or such that can fit, have a decent legs and leveling that fancy you and blends in how you like it. Start from larger furniture stores where you live and insist on checking it up when you finally think you found what you want. Hate that part personally.

 

[TheBatsEar]

No, I was being ironic, poor attempt at humour. Burnout is where you believe that the sound quality degrades over the initial couple of weeks ownership.

I see, never heard of it that way, as a joke or serious.

I am struggling to find a replacement for my ancient pine cabinet, which is about 5cms to shallow, so the yamaha's nose is poking out of the front. It won't do, and I can't find anything at a sensible price that would work. Where did you get your from, and what is the approx width, as I've not got a lot of space to play with....

The usable width is 56cm (most Hifi devices are 43cm/19" wide, so plenty of space) and the depth is 43cm, but since it's open on the back it doesn't matter. The A-S701 fits. However, getting one is a matter of patience i'm afraid.

I got mine via a classifieds page in Germany, called Ebay Kleinanzeigen, not to be confused with Ebay Auctions, same owner, but different page.
I also had good luck with Hifi-Shark whenever i looked for something hifi related:

Used Yamaha Ambiente for Sale | HifiShark.com

Used Yamaha Ambiente for sale on 300+ second hand hifi sites & shops. Use Hifi Shark to monitor pricing and global availability

www.hifishark.com

The results are scraped from sites all over the world. Just one listing for 300€, which i find pricey. I think max 100€ is ok, 50€ is a very good price. If you get one, you'll have it for decades, it's style is timeless and it's made very solid.

If you want to have a solution now and you don't want to pay much money, check out the Ikea Lack table rack (3 times 17€ i think) i used a few years ago, plenty of space, even for a A-S 1000:

If you plan to collect things, this is an Ikea Billy bookshelf (60€ i think, the one that is 40cm deep). Fits a A-S701 as long as you don't add doors (i have doors and have to remove the knobs from larger amps to close them):

I have two of them full of stuff i want to keep, or repair and sell. Starting a third one soon.
It's a hobby alright.

 

[Bernard23]

I see, never heard of it that way, as a joke or serious.


The usable width is 56cm (most Hifi devices are 43cm/19" wide, so plenty of space) and the depth is 43cm, but since it's open on the back it doesn't matter. The A-S701 fits. However, getting one is a matter of patience i'm afraid.

I got mine via a classifieds page in Germany, called Ebay Kleinanzeigen, not to be confused with Ebay Auctions, same owner, but different page.
I also had good luck with Hifi-Shark whenever i looked for something hifi related:

Used Yamaha Ambiente for Sale | HifiShark.com

Used Yamaha Ambiente for sale on 300+ second hand hifi sites & shops. Use Hifi Shark to monitor pricing and global availability

www.hifishark.com

The results are scraped from sites all over the world. Just one listing for 300€, which i find pricey. I think max 100€ is ok, 50€ is a very good price. If you get one, you'll have it for decades, it's style is timeless and it's made very solid.

If you want to have a solution now and you don't want to pay much money, check out the Ikea Lack table rack (3 times 17€ i think) i used a few years ago, plenty of space, even for a A-S 1000:
View attachment 261226
View attachment 261228

If you plan to collect things, this is an Ikea Billy bookshelf (60€ i think, the one that is 40cm deep). Fits a A-S701 as long as you don't add doors (i have doors and have to remove the knobs from larger amps to close them):
View attachment 261227

I have two of them full of stuff i want to keep, or repair and sell. Starting a third one soon.
It's a hobby alright.

I looked at LAK, thanks for the suggestion. I found a couple of pieces of "mid century antique" racks, they're from the 80s made by Nathan and match an old dresser that's adjacent. It solid teak, so looks quite OK and is big enough. I also asked a chap I know locally to price up a custom wooden rack that would also accommodate my LPs.
Back to the Yamaha, the phono section would appear to be it's weak spot. I've just hooked up my old CA 540p phono preamp, and I'm sure it's much better. The AT is singing like a happy canary now, could just be the loading of course, but the 270C sounds equally vibrant.
The other downside is that the bass can get a bit sloppy, it's too easy to overpower my room, despite a - 6dB notch filter at 50Hz and a - 3dB low pass shelf from 70Hz to shift the LF duties to the sub, which is turned down to around 25% volume. My mind is trying to convince me that the Denon is snappier, bigger sounding, but it's definitely not as flat LF response as the Yamaha, so it's likely to be room / ear responses. Once again, the benefit of correcting room response with some DSP is apparent, this needs more work but that's for another day. However, any differences real or not are tiny asti being insignificant, so the Denon is already up for sale. I now await the arrival of the new NAD streamer to replace the ageing but perfectly capable sonos connect, but first a rack that fits the newcomer; then the experiments with sorbothane and the Technics shall commence in earnest!

 

[WDeranged]

Thank you so much for this, I never ceased to be amazed by our membership. If I'm reading this correctly, it seem that the phono output section is somewhat average. Would it be a good idea to use a separate phono preamp and just run it to line in?

I have the 301 and as far as I'm aware the phono section is the same. It's not inspiring, especially if you prefer a more detailed, punchy sound. I heard a similar sound from the Rega Fono Mini, the laid back feel is something many people enjoy.

I tried a Schiit Mani (1st gen) and it was a big step up but I eventually settled on an Ifi Zen.

 

[Bernard23]

Tbh, the more I listen, the more I think this amp is a good easy listening device. A week in and I don't get that excited when I'm listening to my system, but I did with the little denon. Unexpected bias, old ears, maybe I just like the taste of distortion.
The phono stage is a big disappointment though. The 540p is hardly sota, but a better option, wonder what an ifi zen might bring to the party.

 

[WDeranged]

I have a question related to the CD input on the 301. As we have no CD Direct feature on this amp, are there any pathway benefits to using it? It does look very much like a separate input, but I wonder if it's really just the same as the other line ins.

 

[Doodski]

I have a question related to the CD input on the 301. As we have no CD Direct feature on this amp, are there any pathway benefits to using it? It does look very much like a separate input, but I wonder if it's really just the same as the other line ins.

 

[WDeranged]

View attachment 262068

Am I reading this right? The analogue CD input is bypassing an internal volume control IC? A mixer?

 

[Doodski]

Am I reading this right? The analogue CD input is bypassing an internal volume control IC?

The Vol and Loudness are just before the amp circuitry. (The Vol L,R indication you see is maybe the PCB reference.)

 

[WDeranged]

The Vol and Loudness are just before the amp circuitry. (The Vol L,R indication you see is maybe the PCB reference.)

I think you're going to have to speak to me like I'm a noob. I see that separate L,R path but I also see the CD input going into an IC like the rest of the inputs.

 

[Doodski]

I think you're going to have to speak to me like I'm a noob. I see that separate L,R path but I also see the CD input going into an IC like the rest of the inputs.

Page 62 of the service manual available here shows more in depth the sophistication of the circuitry as compared to the block diagram.

 

[harrisonjr98]

So I got an unbelievable steal on one of these ($350, mint used) and I love the industrial design and performance measurements. In the AVR world I have been in for years, even the most exciting new gear feels disposable as the video tech advances so fast. I *love* the idea of a classic integrated stereo receiver sans crappy LCD screen or rapidly outdated tech. Just a solid amp to do the part and last decades.

Anyhow, I have always run 2.1 in my main setup, as I am about 50/50 music/movies but broadly more concerned with the fidelity of music than cinema. I am coming from an AVR that had bass management features, IE high-passing the mains at the crossover point of the sub to reduce load on the amp + speakers alike. I never used the HDMI passthrough or DSP stuff in the AVR and would love to outright replace it with the 701.

I have been scouring this and other forums for opinions on the necessity of HPF for mains in a 2.1 and my god are people split on the issue. In my mind there has to be a reason that next to zero integrated stereo amps have this feature- surely a better reason than the oft-quoted “people that buy these hate subwoofers anyway, if you want a sub get an AVR”… Well, this and other stereo amps offer the volume controlled sub out and I have a hard time believing they’d leave out a crucial feature if it really made that much of a difference?

TL, DR- I have always taken a HPF for mains in a 2.1 for granted and went down a rabbit hole upon discovering that it is uncommon in integrated stereo amps. I’d like to replace my AVR with this amp and make it the centerpiece of my hybrid music/film setup for years to come. Am I overthinking things?

 

[TheBatsEar]

I have a hard time believing they’d leave out a crucial feature if it really made that much of a difference?

In my opinion, a HPF would be better, but the designs of our amps go back decades and there is inertia to make changes. Luckily you can solve the problem by using a MiniDSP 2x4 HD or Flex. These allow you to fix other things as well, such as nasty room gain at certain frequencies.

At least Yamaha has a variable loudness, i think they are the last manufacturer that does it correctly.
But then they have removed rec select and the pre-out/main-in loop to save a few cents.

 

[peng]

Am I reading this right? The analogue CD input is bypassing an internal volume control IC? A mixer?

No, the diagram Doodski posted, shows CD direct bypasses the tone control, but not the volume control IC (as you alluded to your post#374). If it bypass the volume IC, then you cannot control the volume!

This would be the same even if you upgrade all the way to the very similar A-S801. The higher models have better spec DAC chips but performance will still be limited by the Volume IC that is an AVR chip so those so called integrated amps are not going to do better (okay may be 1 to 3 dB SINAD better for the A-S801) than say an AVR such as the RX-A2000/3000 series.

If you are keen on, such as chasing higher SINAD and thinking an integrated amp will do it, then you probably should stick with the older models such as the A-S700 as those are more like a real integrated 2 channel amp that does not use AVR volume chips. It doesn't mean they will "sound better", but they may be more suitable to the "purist" who believe the more discrete circuity there is, the better.

 

[peng]

So I got an unbelievable steal on one of these ($350, mint used) and I love the industrial design and performance measurements. In the AVR world I have been in for years, even the most exciting new gear feels disposable as the video tech advances so fast. I *love* the idea of a classic integrated stereo receiver sans crappy LCD screen or rapidly outdated tech. Just a solid amp to do the part and last decades.

Anyhow, I have always run 2.1 in my main setup, as I am about 50/50 music/movies but broadly more concerned with the fidelity of music than cinema. I am coming from an AVR that had bass management features, IE high-passing the mains at the crossover point of the sub to reduce load on the amp + speakers alike. I never used the HDMI passthrough or DSP stuff in the AVR and would love to outright replace it with the 701.

I have been scouring this and other forums for opinions on the necessity of HPF for mains in a 2.1 and my god are people split on the issue. In my mind there has to be a reason that next to zero integrated stereo amps have this feature- surely a better reason than the oft-quoted “people that buy these hate subwoofers anyway, if you want a sub get an AVR”… Well, this and other stereo amps offer the volume controlled sub out and I have a hard time believing they’d leave out a crucial feature if it really made that much of a difference?

TL, DR- I have always taken a HPF for mains in a 2.1 for granted and went down a rabbit hole upon discovering that it is uncommon in integrated stereo amps. I’d like to replace my AVR with this amp and make it the centerpiece of my hybrid music/film setup for years to come. Am I overthinking things?

How about the R-N803? It is now discontinued so there may be good deals. It has some bass management features that the integrated amps don't have. Measurements will likely be the same or a little better than the A-S701. It has the same volume IC, but a better Dac, the ES9006AS, the A-S701 has the PCM5101A.

Yamaha R-N803 Smart Receiver Review

This is a review and detailed measurements of the Yamaha R-N803 Receiver, amplifier, and streamer. It was purchased by a member (b-stock?) and drop shipped to me. The R-N803 costs US $750 from amazon including Prime shipping. The R-N803 has AV-style features such as Room EQ but with only two...

www.audiosciencereview.com

 

[TheBatsEar]

The R-N803 has the same mechanical build, power supply, heat sinks and power amp section as the R-S700, A-S700/701/801 and R-N800A.

However, they have different signal-to-noise at 200mv input, according to Yamaha:
A-S700 has 110dB
A-S701 has 99dB
R-S700 has 107dB
R-N803D has 100dB
R-N800A has 100dB

I suspect the more electronics, the worse signal-to-noise gets.
They stopped touching/optimizing the power amp section and mechanical build 16 years ago.