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

[mhardy6647]

I've used a composite video switchbox successfully for this. It needs to be a decent brand though, with a well regulated power supply to minimise the introduction of jitter.

I don't know why one wouldn't simply use a passive switchbox (FWIW).
I will give it a go some time & report back.
Not today, though -- we're doin' unexpected grandparent duty today... COVID-related day outta day care for our little grandson (not his COVID... at least until & unless the test he had yesterday shows otherwise).

 

[audio_tony]

I don't know why one wouldn't simply use a passive switchbox (FWIW).

I used an active switchbox in an effort to maintain correct impedance and minimise the risk if interference.

However there's no reason why a passive switch wouldn't work, however it may introduce some jitter (which is unlikely to be a problem anyway).

 

[trl]

I'm cross posting my question here that I had originally put in the THX 789 thread as I'll likely get a response from someone with experience with my Amp.
I recently purchased from Drop a pair of HD6XX and a THX 789 to go with it. My system at home now looks like this: Yamaha A-S801>THX789>HD6XX. I have to set the gain on the THX at 3 otherwise I need to max out the volume on the THX, is this normal? Seems like it should be getting a strong signal from my Amp (line out) and I would not need to raise the gain so much. Going straight into the headphone jack on the Yamaha it has no problem getting the headphones to too loud with barely having to turn the volume dial.

The Yamaha is likely outputing a nominal 200mV via the tape outs, not 2.0V like a D/A converter would. That is deliberate as line levels are typically 150-200mV in tape loops.

View attachment 179295

Just factor of 10, so yes, you'd need higher gain settings on your HP amp.

There are couple of pages here without any measurement and I don't understand why, @hwshi? It is not so complicated to use a voltmeter/multimeter and measure the outputs of your A-S801 while it's fed by a 1 kHz signal on USB or Optical.

I measured my A-S701 right now, while being fed by my XBOX X while playing a 1 kHz signal from Spotify on the Optical cable and I got a constant 1.815 V RMS on both Rec-Out. Probably with a real DAC, instead of the XBOX, I would get a figure more close to 2V RMS, although this is not the point, the point is that you need to measure the output voltage in your setup and identify where the issue is coming from.

From my point of view you can use your existing setup as it is if you want to keep your desk clean, just need to figure yourself out where the volume/gain problem comes from and to fix it.

 

[Blew]

Thanks for the teardown and measurements. I am seriously considering buying a A-S701 to use with a pair of (yet to be determined) floorstanding speakers. So I want to keep power output options open and not limit myself in speaker options. This seems like great bang for buck in pure analog amplification, but I have a few questions.

1. How does the DAC compare to the ES9068AS used in many external DACs that have been reviewed well here? Is it worth using an external DAC instead of the internal DAC in this amp?

2. Is it possible to configure the subwoofer crossover filter level as you can on the R-N803? The manual says the cutoff is 90Hz, which I'd rather be able to adjust for different speakers than be restricted to just the one level. My sub is very basic and doesn't have a configurable cutoff filter, and I'd rather not have to buy a new one just for this amp.

3. Is there anything else decent that compares to output and SINAD in this price range? The Cambridge Audio AXR85 looks pretty good too, but unfortunately doesn't have a dedicated subwoofer out.

Thanks!

 

[trl]

1. A-S701 has no USB-in, A-S801 does. However, an external DAC might be a better choice.
2. It has a fixed LPF freq., like stated in the specs. You need a sub with adjustable crossover freq.
3. Feel free to compare the measurements, but you can always use a RCA splitter for getting a sub-out this way. Of course, you need a sub with it's own crossover.

 

[restorer-john]

2. It has a fixed LPF freq., like stated in the specs. You need a sub with adjustable crossover freq.

The LPF frequency could be easily adjusted by making minor modifications.

Here is the relevant part of the schematic:

 

[TheBatsEar]

Do we have any measurements on the deviation from RIAA in the phono preamp?

I have an offer for a R-S700 (basically a 701 minus the DAC, plus a FM section). The R-S700 has pre-out/main-in and rec out, which would make it a nifty DSP-able pre-amp in my second system.

 

[trl]

Not sure if this is what you're looking for: https://www.audiosciencereview.com/...nals-few-measurements.9459/page-7#post-632325.

 

[TheBatsEar]

Not sure if this is what you're looking for: https://www.audiosciencereview.com/...nals-few-measurements.9459/page-7#post-632325.

Nope, those numbers give distortion and noise. I'm lloking for frequency response in comparison to a perfect RIAA curve. The curve is used to "encode" and "decode" records.

RIAA equalization - Wikipedia

en.wikipedia.org

 

[AnestisMania]

Lately i was thinking of getting a new amp for my speakers (b&w 604 s3) but i'm in a dilemma.
I know the speakers are kinda power hungry so i was thinking something like a crown audio xls-2002 but i just love the yamaha line up and the yamaha a-s701 is looking soooo good... (also looking for the yamaha as 1200 but kinda out of my price range) any ideas or info that could help in my dilemma?.

I know im trying to compare 2 entirely different things but... yeah.... i just think that my speakers could "use" the extra power

If we go with the crown
crown audio xls-2002 amp
Yamaha wxc-50 pre-amp/streamer

if we go with the yamaha
yamaha a-s701
and Yamaha wxc-50 pre-amp/streamer

Thank you for your time !

 

[MacCali]

Lately i was thinking of getting a new amp for my speakers (b&w 604 s3) but i'm in a dilemma.
I know the speakers are kinda power hungry so i was thinking something like a crown audio xls-2002 but i just love the yamaha line up and the yamaha a-s701 is looking soooo good... (also looking for the yamaha as 1200 but kinda out of my price range) any ideas or info that could help in my dilemma?.

I know im trying to compare 2 entirely different things but... yeah.... i just think that my speakers could "use" the extra power

If we go with the crown
crown audio xls-2002 amp
Yamaha wxc-50 pre-amp/streamer

if we go with the yamaha
yamaha a-s701
and Yamaha wxc-50 pre-amp/streamer

Thank you for your time !

Depends what sound signature you are seeking, so far I have noticed that parasound amplifiers seem to be really beast power delivery wise. They have really high current/amps and also fairly high peaks.

I would suggest the vintage models, anything between 97-2005. However, will warn it is a warm sound signature which to me is pleasant.

I have owned the HCA-1000, 1200 MKII, and currently own two HCA-1500's running my system in mono bi amped.

The HCA 1500 is an excellent amp, I think it's not biased in class A very high even though it's claim is to be higher than it's little brothers. The amp never gets hot even when I am playing near reference volume. Hardly luke warm. I can virtually see no way of this amp failing when the internals are not getting cooked.

However the HCA-1000 gets super hot, but sounds much warmer. The 1200 is in between, the 1500 is least warm.

Not going to hate on the new parasound, it maybe more towards your taste. But they are expensive. All four of those amps cost me 1500.

 

[TheBatsEar]

Lately i was thinking of getting a new amp for my speakers (b&w 604 s3) but i'm in a dilemma.
I know the speakers are kinda power hungry

The manufacturer says 90dB sensitivity, 25 to 200W into 8 ohms, with a dip to 3 ohm (frequency unspecified).

The A-S701 and A-S1200 could drive this one to "very loud".

If you want to save money, replace the A-S701 with a used R-S700 or the A-S1200 with a used A-S1000.
I would go with a R-S700 for 200€ or so. If it is enough, you are done, if it's not enough, sell it for the same price you bought it.

Can't say anything about Crown.

 

[AnestisMania]

Thank you both for your time and suggestions I shall take them into consideration going forward.

Depends what sound signature you are seeking, so far I have noticed that parasound amplifiers seem to be really beast power delivery wise. They have really high current/amps and also fairly high peaks.

Yeah I know parasound amps are little beasts but most of the time the price is kinda out of what I would like to pay for good value.

So far I was using my old vincent sv 238 for the speakers and my god they had detail and bass.. but since I sold it for space reasons i just hooked em up to a Denon 4400x and let them 'die' there ..

So yeah I will also take a look at parasound.

If you want to save money, replace the A-S701 with a used R-S700 or the A-S1200 with a used A-S1000.
I would go with a R-S700 for 200€ or so. If it is enough, you are done, if it's not enough, sell it for the same price you bought it.

Hmm yeah it seems I will be going for an adventure again.. I found out some one is has in auction a Yamaha as 2100 sure the older line up but if I can get it for 1000/1200 euros it's going to be Worth it.

Thank you again for the quick reply.

 

[Scytales]

Few basic measurements done with Xonar U7 and Focusrite Solo 3.

First measurements were done with my Picoscope that showed a 35mV DC voltage on output. This is a respectable value for an amplifier that is able to push over 30V RMS on 8-Ohms speakers. I've seen headamps with 20-30mV of DC.

View attachment 36396
Ruler flat from 10 Hz to 22 KHz


View attachment 36397
Impulse response of the built-in DAC (optical input from Xonar U7 used as USB transport)
​

The below measurements were done without vs. with speakers connected, to show the influence of the 3-ways speakers for the output stage and the measurements values differences. The voltage used was around the value of 4.5V RMS, so a 5 W was used as reference here, as Amir suggested in his own power amps reviews. However, increasing the volume will lower the THD+N and increase the final SINAD. External DAC used was Conductor V2+ on DAC-Out (PRE-Out is too noisy due to the internal pre-amp chip).

View attachment 36400
External DAC used on CD-input, CD-DIRECT pressed, no speakers connected, 1 KHz


View attachment 36398
External DAC used on CD-input, CD-DIRECT pressed, real 4-Ohms speakers connected, 1 KHz


View attachment 36404
Built-in DAC (COAX-input), CD-DIRECT pressed, no speakers connected, 1 KHz

View attachment 36402
Built-in DAC (COAX input), CD-DIRECT pressed, real 4-Ohms speakers connected, 1 KHz
​

Seems that the Conductor V2+ has a better DAC inside than the A-S701, because with speakers connected I was able to get a THD+N of 0.0046% vs. 0.0071%.

Usually, when speakers are connected, the low-end of the audio band is more impacted, so below tests are with 50 Hz sines.

View attachment 36401
External DAC used on CD-input, CD-DIRECT pressed, no speakers connected, 50 Hz

View attachment 36399
External DAC used on CD-input, CD-DIRECT pressed, real 4-Ohms speakers connected, 50 Hz

View attachment 36405
Built-in DAC (COAX-input), CD-DIRECT pressed, no speakers connected, 50 Hz
View attachment 36403
Built-in DAC (COAX input), CD-DIRECT pressed, real 4-Ohms speakers connected, 50 Hz
​

Again, the external DAC connected to CD-input was measuring a bit better than the built-in one for 50 Hz test signals as well, with a THD+N of 0.0052% vs. 0.0080%.

So, for 5 Watts of power on 4-Ohms speakers connected and external DAC playing sines I got a THD+N of 0.0046% with 1 KHz and 0.0052% with 50 Hz.

Great work !

Well, when you wrote : "the external DAC connected to CD-input was measuring a bit better than the built-in one for 50 Hz test signals as well [as for 1 kHz]", that's not that simple.

When we compare THD and THD+N for both configurations, it appears that the internal DAC produces about 5 to 7 dB more total harmonic distortion than the external one whereas the connection to this external DAC produces more noise, hence the lesser THD+N.

I guess it all depends on priorities.

 

[MacCali]

Thank you both for your time and suggestions I shall take them into consideration going forward.



Yeah I know parasound amps are little beasts but most of the time the price is kinda out of what I would like to pay for good value.

So far I was using my old vincent sv 238 for the speakers and my god they had detail and bass.. but since I sold it for space reasons i just hooked em up to a Denon 4400x and let them 'die' there ..

So yeah I will also take a look at parasound.

Hmm yeah it seems I will be going for an adventure again.. I found out some one is has in auction a Yamaha as 2100 sure the older line up but if I can get it for 1000/1200 euros it's going to be Worth it.

Thank you again for the quick reply.

Yea, they just caught my attention cause they are THX certified. Numbers look good, it's the only bottle neck in my system measurement wise as everything else is upper echelon. I hear absolutely nothing impacting the sound even at full volume they provide THD which isn't even audible but my speaker starts to fall apart before the amp. They have gain control which is nice I think for preamp pairing that many amps do not have.

Also best part, reason why I chose them is you can bi amp any speaker. Even 4 ohms with the loop function. Rather than running bridged mono, you do R channel to bass and loop R to left and put left channel output to mid and treble. Eliminating crosstalk for solid channel separation.

 

[NewbieAudiophileExpert]

I'm considering purchasing a A-S301 in the near future, which I believe is the same as the 701, minus the wattage - please, correct me if i am wrong.

This may sound like a silly question, but in the real world, how much better would the A-S301 be than a Aiyima A07 or A08?

 

[TheBatsEar]

I'm considering purchasing a A-S301 in the near future, which I believe is the same as the 701, minus the wattage - please, correct me if i am wrong.

Yep.
There is one more feature called Direct CD or something like it. Not worth anything in my opinion.

This may sound like a silly question, but in the real world, how much better would the A-S301 be than a Aiyima A07 or A08?

In terms of features? Lots.
In terms of power? A bit better with harder to drive speakers.
In terms of size? Worse.
Price? Worse until you buy used.

I think this is easily won by the Yamaha because it has a a remote, a DAC, a phono preamp and a subwoofer output builtin.

 

[Overseas]

If you cannot put up the budget for AS501 minimum, going for Loxjie A30 is my advice. Enjoy the music then.

 

[NewbieAudiophileExpert]

Yep.
There is one more feature called Direct CD or something like it. Not worth anything in my opinion.


In terms of features? Lots.
In terms of power? A bit better with harder to drive speakers.
In terms of size? Worse.
Price? Worse.

I think this is easily won by the Yamaha because it has a a remote, a DAC, a phono preamp and a subwoofer output builtin.

What about the quality of sound? I've heard immense things about the Aiyima 07.

If you cannot put up the budget for AS501 minimum, going for Loxjie A30 is my advice. Enjoy the music then.

The Loxjie A30 seems like a good alternative to the 301 - though my main concern is the sound quality going from class D SMPS to a class AB w/ iron core transformer.

 

[Doodski]

The Loxjie A30 seems like a good alternative to the 301 - though my main concern is the sound quality going from class D SMPS to a class AB w/ iron core transformer.

You are over analyzing things.