Yamaha A-S701 Stereo Amplifier Review

[BlueMax]

EDIT : Where have you seen measured results from CD Direct? I've been unable to find any.

Actually, Amir’s test of the 701 in this very thread has been “done with CD direct unless otherwise noted. As you see above and manual states, it produces best performance. You lose all the controls though if you turn it on.”

Only problem was finding out how much of a degradation to the signal turning it off brings. It seems that it’s about 4-5dB difference. It shouldn’t be audible under most normal circumstances and 701’s set of measurements is great for real world use after all, with or without direct modes engaged.

 

[Ruediger]

It's nice the option exists for everyone who wants to use the amp as a poweramp. And has all the controls before the Yamaha already.

 

[antcollinet]

Actually, Amir’s test of the 701 in this very thread has been “done with CD direct unless otherwise noted

Yes, I know - but only with that - so no comparative measurement showing the difference. The 4dB or so stated above is in the sort of range I would expect. But it would be nice to see a set of tests done : Here with CD direct - here the exact same test setup - without it.

 

[JRob1125]

I have the R-S700, the all-analog receiver version of the A-S701.

I can't hear a lick of difference between pure direct being on or off, but CD Direct is slightly different. Maybe it's placebo, but it sounds "lifeless" to. I can definitely hear the very slight hiss max volume all but vanish with CD Direct on though, I just prefer it off. Plus not being able to select the other inputs annoys me

I leave pure direct on for all sources simply for the piece of mind from knowing it's the cleanest path

 

[Randolf]

I have the R-S700, the all-analog receiver version of the A-S701.

I can't hear a lick of difference between pure direct being on or off, but CD Direct is slightly different. Maybe it's placebo, but it sounds "lifeless" to. I can definitely hear the very slight hiss max volume all but vanish with CD Direct on though, I just prefer it off. Plus not being able to select the other inputs annoys me

I leave pure direct on for all sources simply for the piece of mind from knowing it's the cleanest path

I agree that in most listening situations it makes little or no difference, but please don't call it a placebo. It has a real implementaion behind it (which you can check in the schematics), its effect is measurable and somtimes audible. You may want to have a look at

NAD C 389 residual noise and first experience

Hi, I purchased a NAD C 389, MDC2 BluOS-D Modul and DiracLive full bandwidth license a few weeks ago. It should replace my current setup WiiM Pro->MinDSP DDR-24 (DiracLive)->Yamaha R-N803D. On the one hand I like der C 389 a lot, but I found it's residual noise rather disappointing, especially...

www.audiosciencereview.com

It compares the audible idle hiss of a Yamaha R-N803D, vintage AX-590 (both very similar to the A-S701) and NAD C-389. You can clearly see the difference in the REW graphs and the effects of CD Direct, Pure Direct. It may look small but the C-389 was that bad that I sold it. A few people may have even higher sensitivity speakers and could really benefit from these bypass features.

In a none idle situation when the music is running I could not hear a difference. But 40 years ago when I was using a Yamaha A-960 for demoing DIY speakers almost nodody could hear the impact of its Main Direct switch except one guy who could clearly identify if Main Direct was on or off to my surprise. This teached me that there sometimes can be things not all (including myself) could hear for whatever reason.

 

[BlueMax]

FYI I will be using the 701 with my Harbeth SHL5plus XD whose sensitivity is specified as 86dB/2.83V/1m axial. Not very sensitive speakers but very easy to drive as their load never falls under 6 Ohm across the frequency range. Should be easy to drive for the 701 and I will report if hiss is ever audible at idle, with Direct features engaged or not.

 

[antcollinet]

but please don't call it a placebo. It has a real implementaion behind it (which you can check in the schematics), its effect is measurable and somtimes audible. You may want to have a look at

Even if there is a real measurable difference, that doesn't stop perceived differences resulting only from perceptive bias (not really placebo - but similar).

I would agree that if one can hear hiss during silence that comes and goes with a flick of a switch, then that is almost certainly real hearing.

But for qualitative descriptions of music - absent a proper blind test - we really can't know. And when the difference is only around 4db better at levels already around -100dB., it is vanishingly unlikely to be possible to hear that level of difference when the music is playing.

 

[Randolf]

FYI I will be using the 701 with my Harbeth SHL5plus XD whose sensitivity is specified as 86dB/2.83V/1m axial. Not very sensitive speakers but very easy to drive as their load never falls under 6 Ohm across the frequency range. Should be easy to drive for the 701 and I will report if hiss is ever audible at idle, with Direct features engaged or not.

Harbeth, very traditional British and the SHL5plus XD is using a super tweeter crossed over at 10KHz (a little bit against common sense) . You will have no problems with these and the Yamaha, not even the noisy NAD C-389 would be problematic.

 

[Spoofer]

That is about what I might expect. You will not hear the difference between 90 and 86dB SNR, nor 111 vs 107dB.

IMO.

I had the 801 and I swear that I could hear a slight difference..

 

[antcollinet]

I had the 801 and I swear that I could hear a slight difference..

I lot of other people would also - if they are doing uncontrolled sighted listening.

 

[Spoofer]

I lot of other people would also - if they are doing uncontrolled sighted listening.

kind of like 1/4 of a Dolby switch...

 

[antcollinet]

kind of like 1/4 of a Dolby switch...

Much much less than this - bear in mind the starting point for noise on a well set up cassette tape deck being around -60dB. The change in absolute noise level between -60 and -70dB (That you might get from Dolby B) is much greater as a noise voltage/power level, then the reduction from -100dB to -110dB

Of the order of 100x greater as a voltage - or 10,000 times as a power.

 

[BlueMax]

I can report that Yamaha A-S701 is a fantastic partner for Harbeth SHL5plus XD. I can hear very very little hiss with volume knob turned right to the maximum with my head close to tweeters and no direct features engaged on the Yamaha. Turning on Pure Direct changes little. Turning on CD Direct cuts by half the initial, very slight, hiss. So it is a non-issue to begin with.

Since you cannot adjust Loudness from remote, the only reason for Pure Direct is that you can turn Loudness knob to the left for TV use and leave it at desired position. When you need to listen to music, you can just use the remote to change source and turn on Pure Direct to disengage Loudness filter.

Overall 701 is a great amplifier. Why would anyone need anything more? I will probably sell my other clutter which are mainly QUADs: 909 power amps and Elite monoblocks. Yamaha is just as good, but much more convenient. I also love how elegant and discrete the 701 is: when it’s on, you just see two (or three with Pure Direct turned on) honey yellow lights, that are very nice to the eye and not obtrusive in the slightest. When you see such details you know that intelligent people designed this amp.

Very happy with the purchase! I started with Yamaha some 20 years ago and I naturally gravitated to Yamaha again. No idea why it took me so long. I should have just kept my first amp and focus on matters that are relevant in this hobby (speakers and room acoustics).

 

[antcollinet]

I can hear very very little hiss with volume knob turned right to the maximum with my head close to tweeters

Please be *very* careful with this sort of testing if you value your eardrums. I'd suggest disconnecting all source devices from the amp before repeating.

 

[ZolaIII]

@BlueMax it's not hiss, it's humm static. When you adjust input gain (higher) and inrernal volume to up to ⅔ it won't be able to hear it with speakers whose sensitivity is under 90 dB from more then 1 m away. While Yamaha ain't best regards self noise of about 22~23 dB (mesured with their active speakers) it's on good side and it ain't coming trough tweter (A-B class). A-S 701 ain't great regarding low end TI DAC (renamed very old and cheap BurrBrown) so analog inputs do better. A-S 801 fixes that will deacent ESS 32 DAC and (gains USB Audio 2.0 input). Old A-S 700 is the last in series that stays in budget category that had old and better Yamaha electro mechanic selector and analog input with SNR of 110 dB. Even older (earlier discontinued) R-S 700 is a same thing with analog radio tuner and loses cuple of dB SNR from the tuner.

 

[BlueMax]

I’m only using Optical input for TV decoder box, so I think that this old BurrBrown is good enough for that purpose. For all other sources I’m using analogue inputs and I’m convinced now that direct features make very little difference, just like in my Yamaha CD player. Audibly it doesn’t matter if I engage them or not. It’s a very well thought out amplifier overall.

 

[ZolaIII]

Well I went analog inputs only with embedded volume control as limiter and DSP processing elsewhere. Almost settled down with A-S700, would completely if it whose in silver color. Have old R-N402D which ain't as good but with input preamp (embedded one) set properly it's more then fine and it's BurrBrown 1701DSD is quite good.
In (almost proper) double blind tests from broader audience of members on ASR the conclusion whose that for power amplifier playing SINAD over 75~76 dB to mid field (2m) dosent make difference. You can amp SINAD rating up as what's rated here as very good starts at about 90 dB for power amplifiers. You won't find a lot of home HiFi speakers with sensitivity over 90 dB (1W 8 Ohms at 1 m) and to reach 100 you will have to go to PA and scale things up in size generally. And that's how good old Yamaha is still quite fine for almost anything you might like to plug on it.
Mind you the human hearing has sensitivity (at reference calibration point) up to 120 dB up in mids but that number falls to 90/80 in highs/lows. As we don't listen on such high (88 dB white noise calibration point stereo) SPL, not even close for deticated listening (74~77 average) and about -12 from that for background one (psy half as loud) and our ability to hear deteriorate quiet rapidly especially in lower bass as SPL goes down it's of more importance to take compensation in SPL boost to the area then minor SINAD hit such circulit may introduce (on such Yamahas and long ago it whose a standard thing on any respectable amplifier). Of course proper DSP filters done in advanced (headroom) precision math flouting point (double precision) won't exhibit any and will glue back to DAC precision (integer) perfectly.

 

[BlueMax]

Well I went analog inputs only with embedded volume control as limiter and DSP processing elsewhere.

I could do just that with my WiiM Ultra and only control volume from the WiiM while using Yamaha volume control as limiter. It’s just more convenient for me to use the Yamaha volume control since otherwise I would need to connect all my sources to the WiiM, which isn’t very convenient. I also doubt I would gain much from that setup.

I used to own Yamaha A-S2100 for some years in the past and I must say that A-S701 is a better thought-out amplifier. For example I couldn’t use XLR inputs on the 2100 without plugging in attenuators since the inputs were just so sensitive. I also found the meters totally useless. I thought I would love them but I didn’t. Useless stuff is getting boring quickly. Only thing that was really good about the 2100 vs the 701 was the in-built phono preamplifier, that was very good on the 2100 and not so much on the 701. Still I prefer to have an average in-built DAC than none at all…

 

[BlueMax]

Please be *very* careful with this sort of testing if you value your eardrums. I'd suggest disconnecting all source devices from the amp before repeating.

Not going to repeat this test. I think I already know everything I needed to know. Direct switches are indeed like the "door close" button in elevators/lifts. They are not exactly “placebo” because technically and measurably they work, just not audibly unless you have some special sort of loudspeaker (horn etc.).

 

[Ruediger]

I could do just that with my WiiM Ultra and only control volume from the WiiM while using Yamaha volume control as limiter. It’s just more convenient for me to use the Yamaha volume control since otherwise I would need to connect all my sources to the WiiM, which isn’t very convenient. I also doubt I would gain much from that setup.

I think that depends on your sources. If they are digital (network, toslink, coax) and you send analog over to the Yamaha, it would then be the ESS9038 in the Ultra doing the DAC job.

That and things like GEQ/PEQ, bass management, RoomFit, gain and volume settings per source are possible things to be had.

If you have analog sources and don't require these functions for any or all of them, then there is no point putting things through ADC/DAC on the Ultra. Especially when you like control and remote with the Yamaha better.