Yamaha A-S701 Stereo Amplifier Review

[Sylvia]

Is there a way to calculate how much power it would produce for 6Ω based on Amir's measurements for 4Ω and 8Ω?

 

[JSmith]

Is there a way to calculate how much power it would produce for 6Ω based on Amir's measurements for 4Ω and 8Ω?

Assuming a linear relationship between power and impedance, circa 150W.


JSmith

 

[Sylvia]

thank you!

 

[catch22]

Since I have both A-S700 and A-S701, I want so highlight some nuances between them, not touching the obvious differences in Inputs.

Not really trying to add something new, as both amps are among the best described amps, including tons of pictures and measurements already, thanks to amir and other members!

Bass/Treble/Balance/Loudness Knobs:
Knobs are the same, but they feel different when rotated:
On 700, they have substantially more resistance to rotate, they feel like normal potentiometers.
On 701, they rotate with very little force applied, meeting almost no resistance. This may be a reason contributing to "cheaper" feel of 701's knobs, pointed by some people.
Overall, build quality looks the same (I have them in different colors so I might miss some nuances in finish of the front panel but look the same).

CD Direct/Pure Direct:
On 700, they are physical on/off buttons (with 2 positions, depressed and extended).
On 701, they are click buttons. This give a possibility to switch 701's CD Direct and Pure Direct rom remote control.
Also, a tiny nuance related to the above: When "CD Direct" is turned on, the 701 automatically switches Input to "CD". This doesn't happen with 700 . On 700 one may be puzzled why there is no sound if "CD Direct" is pressed accidentally. Similarly, when Input knob is moved from CD to something else, on the 701 "CD Direct" is automatically deactivated (which is not possible for the 700 for obvious reason that the button is a mechanical switch). This is a nice touch for the 701. Although I do prefer old-school mechanically activated/deactivated circuits of 700 rather than logical switching of 701.

Rear panel:
700: No Sub-out; No Auto-Standby; 2 switched sockets for other equipment (on a European model) - YMMV
701: Sub-out; Auto -Standby; NO sockets.
Note: there is no Rec-out selector on 701's Front, but Rec Outs are still there on the rear.

Level of Volume:
The 701's specifications declare slighly higher power (100W into 8Ohm 0.019% THD vs 90W for the 700), but the 700 is slightly louder at the same position of the volume knob. When I tried to achieve exactly the same volume (to my ear, not measured) switching back and forth between the two, the 700 was at 8.45 but 701 was at 9.15. Maybe this is because of different curve of volume control. I didn't try the full volume so can't say if one has more power.

Hiss:
With full volume and without input, there is a slightly audible hiss from tweeter for both amps from 15-20cm distance.
Slightly louder for 701. This is probably as expected - SNR declared by Yamaha is 110db for the 700, and 104db for the 701. Of course not noticeable when listening

Sound:
Switching between A-B, I am unable to pick up any difference whatsoever. I would be very much surprised otherwise

A-S700:

A-S701:

 

[LoFiAudiophile]

Do you mean he was impressed by the built in phono pre-amp of the 701 or not? I have absolutely no doubt there are cleaner pre-amps on the market. But the million dollar question is how much it matters? It’s a completely flawed medium compared to digital solutions. I completely understand people’s love for vinyl. I miss it sometimes myself. I just think pursuing absolute fidelity in a turntable is a bit like bringing a knife to gunfight with today’s technology and the 701’s preamp is perfectly fine if you choose to enjoy vinyl.

From what read the phono stage in AS-701/501/801 is accurate to 1dB across the audible frequency range and has ~ 2.5x headroom over the physical limits of the max voltage (~20mV) that can be generated by a 5mV cartridge.

This unit has an audibly transparent phono stage by objective criteria. There are missing features like a dedicated click/pop filter but the bass roll off below 20Hz compensates a bit for it.

 

[Retrobob]

Thank you for this amazingly useful resource. I have quite a bit to learn.

I have a newbie question regarding this amp and the discussion regarding the input voltage for the CD input and potential for clipping. Forgive me if this is the wrong place to post.

If I understand correctly, the amp spec allows for a max input signal of 2.2 volts.

I have nominal 6 ohm speakers with a minimum of 3.1 ohms, 88 db @2.83 V and 1 m sensitivity - no sub.

I listen at 5 m and measured (cheap meter) around 75 db at the listening position, which I calculate via an online spl calc to be less than 5 W (which seems crazy low) from the amp (not sure about peaks).

With a WIIM Pro Plus or Chromecast Audio set to 2 Vrms output and connected to the AS-701 CD input I never go past 9 o’clock on the volume control on the amp (sorry I don’t know how to measure the gain).

My question is: Should I be running with 2 Vrms output to the CD input or should I use something lower to reduce the risk of clipping?

For example: Chromecast I believe has the option of 1.6 V if I disable the “high dynamic range” and WIIM offers 1 Vrms, 800 mVrms, 500 mVrms or 200 mVrms.

Many thanks

Bob

 

[Willem]

But in this thread several are commenting that they like low volume listening at night. I like defeatable controls during the day but I also listen at night and it's hard to beat loudness control on an AB amp when you also listen at low volume.

I considered a class D amp with balanced inputs (there are cheap, excellent ones that have been tested here) but then I've got to find a pre-amp which has loudness controls and balanced out. And that's, what, McIntosh territory then?

I'm a newbie though: I don't know how you'd objectively measure how things sounds at lower volumes... But I sure know several of those fancy McIntosh owners do swear by (defeatable) loudness control and so do many Yamaha owners.

As someone contemplating buying a Yamaha amp right now, I admit I love the vintage look. And I want defeatable loudness control.

The loudness control is very useful, and sorely lacking on nearly all modern electronics. It serves to adjust the frequency response for the reduced sensitivity for higher and particularly lower frequencies of our hearing at lower listening levels (See Fletscher Munson equal loudness curve). So it should act more aggressively the lower the volume. In the old days, most amplifiers had such facility, but unfortunately only rarely adjustable like here. The RME ADI-2 DAC has the most sophisticated adjustable loudness control, but I don't know of any other modern preamplifier. In my experience it is just about the most important thing to look for in real life audio (apart from dsp equalizationj of room modes).

 

[restorer-john]

74 mV + 40 dB at 1 kHz = 7.4 Vrms, which is about what I'd expect in terms of output at +/-13 V. The only way they could have increased the overload margin would have been by decreasing the gain. It baffles me that they didn't do just that on the A-S701. (But things don't always make complete sense with Yamaha. I have the feeling they like to use preexisting circuit blocks like Legos.)

Input filtering is also a fair bit better on the lesser model, 1k/470p seems crude and is unlikely to satisfy many cartridges.

One thing I do not like about the A-S301 circuit is its use of 100µ/16 V capacitors on rails of over +/-13 V. Those should have been 25 V types in the interest of reliability. Modern electrolytics' average actual sustained voltages tend to be much closer to rated voltage as a result of quality improvements. Where back in 1980 they may have needed to target a multiple of rated voltage to make sure that all reasonable outliers would still make the cut, improvements in manufacturing have reduced the spread considerably. That has brought down their size but also means the average capacitor of a given rating will sustain less voltage than back in the day, and degrade faster particularly in a no-voltage scenario. (Hence why I'd generally advise to match capacitance and size rather than rated voltage when recapping, unless it gets silly. For decoupling caps, about 3x rail voltage is enough.)

Let's talk about the placement and value of C611 in the two schematics...

I agree with you about building blocks. Yamaha and many other brands have done that forever. Take Rotel- they really haven't changed a thing in the analogue stages for over 35 years. Lux built their gear the same way in the 1970s. Yamaha, to their credit, clearly had an upper tier division where they gave them the budget and the freedom to push the boat out and create some cool stuff. Trouble is, it didn't really get promoted.

 

[Willem]

I agree. The A-Sx00 models were essentially the same of course, but the D/A in the A-Sx01 series in reality costs nothing, and adds a bunch more inputs and flexibility. People can use it, or not.

A few years ago I bought an AS501 for 359 euros for my student daughter. She likes music but does not want to think about audio. It is perfect for her, and she likes the clean looks. Sonically, I hear no difference compared to my own rather more expensive gear, and the power is more than enough for her current situation, and probably also for quite a few more years, given rising house prices. She uses it with a Chromecast Audio and for better TV sound.

 

[Willem]

Thank you for this amazingly useful resource. I have quite a bit to learn.

I have a newbie question regarding this amp and the discussion regarding the input voltage for the CD input and potential for clipping. Forgive me if this is the wrong place to post.

If I understand correctly, the amp spec allows for a max input signal of 2.2 volts.

I have nominal 6 ohm speakers with a minimum of 3.1 ohms, 88 db @2.83 V and 1 m sensitivity - no sub.

I listen at 5 m and measured (cheap meter) around 75 db at the listening position, which I calculate via an online spl calc to be less than 5 W (which seems crazy low) from the amp (not sure about peaks).

With a WIIM Pro Plus or Chromecast Audio set to 2 Vrms output and connected to the AS-701 CD input I never go past 9 o’clock on the volume control on the amp (sorry I don’t know how to measure the gain).

My question is: Should I be running with 2 Vrms output to the CD input or should I use something lower to reduce the risk of clipping?

For example: Chromecast I believe has the option of 1.6 V if I disable the “high dynamic range” and WIIM offers 1 Vrms, 800 mVrms, 500 mVrms or 200 mVrms.

Many thanks

Bob

WIth a lot of gear I would prefer to chose a somewhat lower output voltage if possible to avoid clipping the input. With a Chromecast Audio and this amplifier I would obviously opt to use the optical output of the CCA into the optical input, just to avoid this risk.

 

[Retrobob]

WIth a lot of gear I would prefer to chose a somewhat lower output voltage if possible to avoid clipping the input. With a Chromecast Audio and this amplifier I would obviously opt to use the optical output of the CCA into the optical input, just to avoid this risk.

Thanks Willem. That’s really useful. I think i am starting to understand what my question should be now.

So if the max voltage to avoid clipping the input is 2.2 volts - i assume this means avoiding peak voltage that exceeds 2.2 volts.

All the devices I have quote Vrms for their outputs. Based on this, my understanding is I need to use an output of 1.56 Vrms (2.2 V peak) or less to avoid clipping the input.

Many thanks

Bob

 

[Retrobob]

@amirm One thing to bear in mind, and to perhaps test, is the input overload on line level inputs on these Yamahas (they all use the same input IC). They will not in my experience tolerate your high level inputs without serious distortion. I note you've tested at 245mV and an arbitrary 1.6V??

About 2.2V to 2.4V is the limit.

Please forgive my ignorance. With that limit of 2.2V to 2.4V, does that mean peak? so you should aim to have an output on whatever you connect to the CD input of 1.56 Vrms or lower to avoid clipping the input?

Just trying to work out what level output I should set my streamer to in order to avoid clipping the input.

Many thanks

 

[Sylvia]

I see this amp has a DC USB power output on the back.
Would it be possible to connect a Wiim Mini through it so that both turn on and off a the same time?

 

[ZolaIII]

I see this amp has a DC USB power output on the back.
Would it be possible to connect a Wiim Mini through it so that both turn on and off a the same time?

It's standard 500 mV USB 2.0 so probably yes. If you have IR on the phone the Xiaomi Remote has the most of Yamaha codes (I have R-N with which it works all do I don't really need it).

 

[WDeranged]

I see this amp has a DC USB power output on the back.
Would it be possible to connect a Wiim Mini through it so that both turn on and off a the same time?

It works fine but if you press Pure Direct it will cut the power to the USB port.

 

[catch22]

It works fine but if you press Pure Direct it will cut the power to the USB port.

Right.. USB power cuts off on all analog sources with Pure Direct. However with "Optical" or "Coaxial" input, the USB stays powered on always. Some weird logic

 

[ZolaIII]

Right.. USB power cuts off on all analog sources with Pure Direct. However with "Optical" or "Coaxial" input, the USB stays powered on always. Some weird logic

Well they understood pure direct quite literally as direct path, everything else off, so they kept direct with basics on and extended set of processing off.

 

[Sylvia]

Thank you for the info!

 

[MidFi Guy]

Speaking of which, besides the HDMI ARC input which the R-N1000A has, the R-N800A looks pretty similar and is quite cheaper. The R-N1000A has a double bottom chassis, slightly better terminals, HDMI ARC and 2 coax in instead of 1 but... That's it? All the specs look the same. And the R-N800A is quite cheaper.

I'm wondering if the added 500 EUR / USD of the R-N1000A compared to the R-N800A is worth it for, basically, an HDMI ARC input which may or may not work with my LG TV and which is, anyway, not the thing I plan to use the most!?

Same DAC, same rated output power, same YAPO, etc. They look very similar.

If anyone has any thoughts on the R-N800A vs the R-N1000A, they're very welcome for I really need an amp to go with my new speakers (not to mention the old amp I'm currently using is going to go back to power my old speakers so I need it there).

I have the R-N800A and love it. Very detailed and neutral with good power. The YAPO works great, but softens the bass. Until I add a sub, I will stick to direct, which boosts clarity a bit. Lots of options to play with to get it to sound best to you in your room. Music only system mostly from Spotify, so didn’t need HDMI ARC. If the 1000 sounds better, I don’t miss it. I have not seen a direct listening comparison review, but I’m guessing it would take a good ear to tell the difference. The specs from the 701 and 800A look identical. Looks like the 800A is a 701 with modern bells and whistles. Works for me.

 

[Zog]

Looks like I'll be staying with my A-S700 for a while longer and upgrading another part of my system ...

I had an A-S700 in my system several years ago. A competent performer to be sure. When I moved to high bias mosfet amps (ATC, Pass Labs, and especially Perreaux) they had more control over my speakers.