Yamaha RX-A8A (Japanese website)

[3dbinCanada]

Based on Audioholic's power measurements of their top 3 tier models, Yamaha easily exceeded their power measurements as stated in their specs when driving 2 channels full bandwidth in both 8 and 4 ohm loads. In fact, whene Gene tested the RX-A3000, it produced power dynamic power than a dedicated Emotiva power amp at full bandwidth. I can supply the link if you need it.

Where Yamaha is perceived to be failing is the ACD test. I say perceived because Yamaha CONSERVATIVELY configures the protection circuitry to trigger at a threshold to prevent any damage from occuring and to keep them out of any legal mess. The ACD test is rather meaningless as it does not demonstrate real world source material. What I have done by driving all 6 channels , 7 channel stereo for the V1800/1900 and 9 channel stereo for the A3050 (RX-V1500 excluded as it has only 5 channels) full bandwidth is as close to a real world ACD test I could get and the AVRs were performing splendidly.

Yamaha has the best reliability record out there for their AVRs and has the lowest number of manufactured defects and returns of any AVR bar none. They must be doing something right.

 

[Macfox]

I firmly believe 4 Ohm minimal impedance isn't an issue with most decent amplifiers in real world conditions. The problem is that speaker manufacturers are even less honest and clear than amplifier manufacturers.
My front speakers are 4 Ohm nominal, with a minimum impedance of 4.2 Ohms and no radical phase changes. They therefore present no extraordinarily difficult load to my receiver. On the other hand, there are many 8 Ohm nominal specced speaker that dip (far) below 3 Ohms with heavy phase changes in the already power hungry low frequency range. But someone going by specs might believe the second speaker to be an easier load.
When manufacturers spec their amplifiers as '4 Ohm approved', they have to take into account speakers that are specced 4 Ohms nominal, but dip far lower.

 

[3dbinCanada]

I understand you point, and I think the issue has something to do with definitions. How do we/they define 4 Ohm rated? Hypothetically, if Yamaha, Marantz or whoever, specified their output specs like 140 W into 8 Ohms, 70 W into 4 Ohms, 1 kHz, 0.08% THD, would that be okay then? If yes, shouldn't we just advise users that if they want to run 4 Ohm speakers, consider the AVR rated 70 W, all will be fine then?

In practice, it should be obvious many Yamaha, Denon users do run the so called 4 Ohm rated speakers with their AVRs for a variety reasons (including just don't know better..), most would likely be fine without blowing anything up because they don't crank their volume high enough. Those 140 W rated flag ship Yamaha AVRs could have been rated 70 W into 4 Ohms legitimately, in fact more likely as high as 90 W just by relaxing distortions slightly, say from 0.08% to 0.1%, and stretching their own definitions (or rule) of their so called "continuous" rating slightly too. It is more complicated but I am simplifying this just to make a point.

Below are just my own rant, please ignore..

The specs of audio gear, on the power side does little to make things clear even for competent designers (just my observations) who may be competent on the electronic/light current side, but may not be all that knowledgeable on the power side. That might be one fundamental reason why the whole thing is such a mess. I can give examples of such "mess" all day as it would be long list. Just to name a few, think about the so called "RMS" power/watts, "Dynamic rating..", "continuous" rating.., "power consumption..", "toroidal" transformer (as if...), so all, or most consumers know much about the true meaning of those terms? What a mess! We would have been in big trouble if engineers on the high power (High voltage, high current) side such as utility companies, steel mills, mining as well as those on the light current side such as in the communication, automation aviation, space industries etc., are as forgiving as their counterparts on the audio electronics side. Fortunately, and naturally, audio electronics don't or very rarely endanger the public.

What this industry desperately needs are regulations and rules to standardize this mess.

 

[peng]

I was refering to Yamaha`s site information about the changes. My wording was bad.

The highly logical and symmetrical internal layout of parts and totally renewed circuit boards are designed to keep the signal paths on each board as short as possible. In order to reproduce the silence and energy contained in the sound as it is, we have generously introduced high-quality parts selected based on the AVENTAGE standard, and redesigned the circuit configuration. The signal path is optimized by adopting a 4-layer board that enables ideal signal, power supply, and ground wiring in the preamplifier section. In addition, the power amplifier section is equipped with a custom-made transformer that separates the power supply windings of the current amplification section and voltage amplification section. In addition to adopting a film capacitor made by German WIMA and a custom-made large-capacity block chemicon, it has achieved a high slew rate that is about twice that of the conventional model, dramatically improving signal tracking and stability. The reproducibility of audio signals including high frequencies such as high-resolution sound sources has been improved.


High Slew Rate Amplifier

The slew rate measures how quickly an amplifier can respond to a rapid change of input level, which contributes to delivering a precise signal transmission and is especially effective with high resolution audio signals. This newly designed circuit achieves both a high slew rate and stable signal transmission, allowing it to handle each audio signal with precision and accuracy

Times have changed with the av-receivers they aren`t as powerfull as they once were with massively heavy boxes, but that applies to all brands these days so i think you are asking bit too much and making Yamaha look worse than it is! People want more features and channels cramped in compact boxes so nothing much other than DAC and features haven`t changed for long time. Now as 10years has passed this new Aventage range is finally offering some changes there aswell.

But the main point was that Yamaha receiver PSU side in these top models isn´t weaker than competitors as you can see from the photos i posted and i mentioned there is lot of these Yamaha flagship owners running 4ohm speakers without any issues if you happen to read any other forums with real world usage powering 7-9 channels to very darn loud levels! They aren´t shutting down like Nad and Arcam which are riding with Dirac Live mostly, they haven`t gone broken, they are running cooler than competitors even if the heatsink look cheap. Yamaha is still number one brand in reliability as informed by M-Code member at AVSF/Audioholics. Biggest worry most people have with Yamaha is that they are stuck with the YPAO, but the company has finally made some changes for the low frequency correction ability. New models will have 5year warranty, D&M 3years.

On the slew rate thing, Yamaha should provide the specs as well don't you think? Just to say quick, rapid just won't cut it. The highly regarded AHB2 power amp has the best measured SINAD, SNR and other parameters yet they are not the champion in slew rate, but one could argue that they are more than high enough for their rated output. I hope Yamaha is not just pulling another claimed benefits such as their 5th foot. If they provide the slew rate specs, then we can all be happy about it, or start another debate over it. Without that, some may consider it just a 6th foot, or like Marantz HDAMs... I am just kidding, obviously, but am serious about wanting to see some specs., not just for the power amp, but for the preamp side as well because the slew rate of the whole audio signal path will still be limited by the weakest link.

 

[peng]

What this industry desperately needs are regulations and rules to standardize this mess.

Agreed, may also benefit by employing competent electrical engineers competent on the power and control side.

 

[Macfox]

I was refering to Yamaha`s site information about the changes. My wording was bad.

The highly logical and symmetrical internal layout of parts and totally renewed circuit boards are designed to keep the signal paths on each board as short as possible. In order to reproduce the silence and energy contained in the sound as it is, we have generously introduced high-quality parts selected based on the AVENTAGE standard, and redesigned the circuit configuration. The signal path is optimized by adopting a 4-layer board that enables ideal signal, power supply, and ground wiring in the preamplifier section. In addition, the power amplifier section is equipped with a custom-made transformer that separates the power supply windings of the current amplification section and voltage amplification section. In addition to adopting a film capacitor made by German WIMA and a custom-made large-capacity block chemicon, it has achieved a high slew rate that is about twice that of the conventional model, dramatically improving signal tracking and stability. The reproducibility of audio signals including high frequencies such as high-resolution sound sources has been improved.


High Slew Rate Amplifier

The slew rate measures how quickly an amplifier can respond to a rapid change of input level, which contributes to delivering a precise signal transmission and is especially effective with high resolution audio signals. This newly designed circuit achieves both a high slew rate and stable signal transmission, allowing it to handle each audio signal with precision and accuracy

Times have changed with the av-receivers they aren`t as powerfull as they once were with massively heavy boxes, but that applies to all brands these days so i think you are asking bit too much and making Yamaha look worse than it is! People want more features and channels cramped in compact boxes so nothing much other than DAC and features haven`t changed for long time. Now as 10years has passed this new Aventage range is finally offering some changes there aswell.

But the main point was that Yamaha receiver PSU side in these top models isn´t weaker than competitors as you can see from the photos i posted and i mentioned there is lot of these Yamaha flagship owners running 4ohm speakers without any issues if you happen to read any other forums with real world usage powering 7-9 channels to very darn loud levels! They aren´t shutting down like Nad and Arcam which are riding with Dirac Live mostly, they haven`t gone broken, they are running cooler than competitors even if the heatsink look cheap. Yamaha is still number one brand in reliability as informed by M-Code member at AVSF/Audioholics. Biggest worry most people have with Yamaha is that they are stuck with the YPAO, but the company has finally made some changes for the low frequency correction ability. New models will have 5year warranty, D&M 3years.

Just one important question: were the old models slew rate limited in their 20-20k Hz range? If not, improving slew rate won't bring actual benefits besides looking nice on the spec sheet. If they were, then the old design was a bad one.
I'd like to know what the limiting factor was in the old design and whether they improved that factor. My guess is it wasn't the DAC used or the slew rate.
It's probably something far less fancy (like volume IC), that they might still have improved, but doesn't look sexy in the marketing story.

 

[blueviewlaguna]

They don´t need to be 6ohm or higher in reality. There is hundreds of people who has run expensive 4ohm nominal speakers in 5.1.4/7.1.2 configurations with the earlier 30x0 models at theater level SPL without any hardening of sound or going to protection! And i believe Yamaha has run cooler than similar D&Ms so those heatsinks are doing the job what is asked from them.

Changes:



Yamaha RX-A3080 and earlier 30000 models uses 18,000uF capacitors where as Denon X6700H uses 15,000uF caps! Naturally the new model should have the same high quality components made by German WIMA and Chemicon.

This is for RX-A3070 bench measurements see for 4ohm load taxing 7channels (2nd last chart on right). What we can see here is Yamaha spanking Denon and Marantz in all 6ohm and 4ohm measurements even when 7channels is taxed continuosly. 129watts for 7channels is not bad with 4ohm, even the beefy SR8012 can`t do that! Of course the differences are small at best, but this is to show that Yamaha isn´t behind D&M like some here are believing.


View attachment 132044

For Denon X6500H:

View attachment 132045

And finally Marantz SR8012 with toroidal psu and 22,000uF caps!

View attachment 132046

The Denon AVR-A110

148 watts @ 4ohm load taxing 7channels (2nd last chart on right).

 

[peng]

The Denon AVR-A110

148 watts @ 4ohm load taxing 7channels (2nd last chart on right).

View attachment 133662

From that chart, it shows that output would continue to increase when impedance decrease from 8 to 6 and then to 2 Ohms even with 7 channel driven. That indicated its power supply and the output devices are truly high current capable, albeit just for short durations. It would be nice if Audiovision.de could tell us the test durations used in their tests, and THD levels as well. Without that, I would assume 1% but it could be higher.

Do we have German speaking members who wouldn't mind contacting them for the information?

 

[3dbinCanada]

On the slew rate thing, Yamaha should provide the specs as well don't you think? Just to say quick, rapid just won't cut it. The highly regarded AHB2 power amp has the best measured SINAD, SNR and other parameters yet they are not the champion in slew rate, but one could argue that they are more than high enough for their rated output. I hope Yamaha is not just pulling another claimed benefits such as their 5th foot. If they provide the slew rate specs, then we can all be happy about it, or start another debate over it. Without that, some may consider it just a 6th foot, or like Marantz HDAMs... I am just kidding, obviously, but am serious about wanting to see some specs., not just for the power amp, but for the preamp side as well because the slew rate of the whole audio signal path will still be limited by the weakest link.

Agreed. If a manufacturer mentions a technical spec, they should dam well put a figure behind it. Now as far as slew rates go, there was nothing lacking on the previous generation top 3 models. Before moving into the town house I have now, I used to crank 6 PSB Image series speakers into the low 90db range running full bandwith with no sub while on the treadmill back on a RX-V1800 and it never got hot nor did the sound ever become harsh. I used to listen to a band called Tool while jogging.

 

[Technomania]

Did I miss something that differentiates the Yamaha?

Of course. Apart from thermal design, power and audio, there is video department too. New Yamahas host 10 (7+3) HDMI 2.1 ports, each 40 Gbps, whereas Denon and Marantz have only one single HDMI 2.1 input which, frustratingly for owners, also require the use of clumsy solution, aka the adapter box, to work well with XboxX console, following the fiasco launch and HDMI 2.1 bug last year... From that point of view, Yamahas are more competitive and future proof in video connectivity.

 

[Technomania]

Yamaha have been using this exact cheap and nasty heatsink since the mid 1980s on everything low-mid range. They must make it themselves as it's been a staple on all their gear and nobody else uses it (for good reason). They have only ever used quality extruded large heatsinks on the absolute TOTL 2 channel gear. AV gear gets two piece crimped crap like this. There is absolutely no way each heatsink is remotely adequate for up to what looks like 6-7 amplifiers on one side and 4 on the other (hard to tell) of class AB amplification running at its rated 150W@8R/ch- that's fantasy land.

Several other companies also use variety of thermal solutions on different tier models. It's not true that only Yamaha uses such solution. Please see other pictures posted by members. Also, it's false comparison a bit. High-end 2-channel separates serve different purpose and different market than AVRs. There is no need to place heavy iron heat sinks into an AVR when its multi-channel performance could be optimised in several ways. Majority of users will never play home theatre based on AVR extremely loudly, so those devices are unlikely to be pushed too much for too long in order to overheat. At the end of the day, A8A model has been offered with 10 year warranty and I am pretty much sure that Yamaha's engineers know what they are doing. Even if a heat sink looks thin or "cheap", that does not really mean too much, as there are surface area and material to be considered too for thermal conductivity.

 

[Technomania]

Amir's previous tests of other recent Yamaha AVRs have suggested so-so measured performance more or less on par for the class and not quite up to the performance of some Denon products:

True, but he has not tested highest tier models and as many models in comparison to Denons.

Not sure what the fuss is about those heatsinks? Provided that they keep the amplifier running reasonably cool, I see no point in costlier, heavier assemblies.

Completely agree.

As for associated apps, plan for few if any future updates and you won't be disappointed: Features which rely on apps will likely be the first to become obsolete.

Nothing to worry about here, as there are so many HDMI dongles and devices that use similar apps. If AVR does not have one, chances are other devices will. High-res music apps are exploding across OS, from Linux to Android, so app support on AVR should be the smallest worry ever.

 

[Technomania]

Apparently Gene has not even looked at the Specs of these hammer drops. From the Manual of their Flagship RX-A8A AVR: Go to page 431 (Audio Section) paragraph and look at the quoted THD %. Yamaha RX-A8A AVR Manual

He is certainly going to rubbish the metrics for "1-channel driven" as the most useless in AV industry.

 

[restorer-john]

Several other companies also use variety of thermal solutions on different tier models. It's not true that only Yamaha uses such solution. Please see other pictures posted by members. Also, it's false comparison a bit. High-end 2-channel separates serve different purpose and different market than AVRs. There is no need to place heavy iron heat sinks into an AVR when its multi-channel performance could be optimised in several ways. Majority of users will never play home theatre based on AVR extremely loudly, so those devices are unlikely to be pushed too much for too long in order to overheat. At the end of the day, A8A model has been offered with 10 year warranty and I am pretty much sure that Yamaha's engineers know what they are doing. Even if a heat sink looks thin or "cheap", that does not really mean too much, as there are surface area and material to be considered too for thermal conductivity.

Yamaha has always been cheap on their heatsinks. Always. Right from the 1970s when everyone else was using extruded aluminium and highly effective tunnel fins, they were still using inadequate folded sheet aluminium which doubled as chassis reinforcement. I know, I've been working on gear for many decades, and own enough of it.

Only their upper/top models have decent heatsinking. In the 1980s, Yamaha integrateds were stripped down to small transformers, inadequate filter caps, not much more than bare minimum SOA for 8R rated and as I said, those cheap crimped "shark fin" heatsinks- the ones they still use. Plenty of other brands used them too, Luxman, Harman Kardon, etc.

Only into the 1990s on their integrateds did they put a little more effort in, although the heatsinks are still inadequate on all but the TOTL models. Multichannel AVRs need much better heatsinks as they are disippating much more standing (idle losses from bias etc) than a 2 channel amp.

I call it for what it is. The heatsinks on AVRs are absolutely inadequate garbage on the whole. Yamaha even have put thermistors on some bridge rectifiers instead of using adequately heatsinked and rated bridges in the first place. The amplifiers/receivers are designed to shutdown as they simply are not capable of delivering what they promise in the specs.

 

[Technomania]

I've seen the damage that people induce on their Yamaha receivers when they run low impedance speakers. I advise not to run 4 Ohm speakers on the mains or the surrounds unless the unit is designed and rated for that.

Could you share some of your experience and reasons why those AVRs were damaged? Was it the case that owners did not properly pair speakers' spec with AVR's specs?

 

[Beershaun]

Could you share some of your experience and reasons why those AVRs were damaged? Was it the case that owners did not properly pair speakers' spec with AVR's specs?

Almost all of Amir's speaker measurements show some portion of the frequency range of of a given speaker to dip to 4ohms and below. Generally it's also in the bass region where more power is needed. I too have concerns about how it would handle the demands of speakers that dip to 4ohms when requiring high power to move woofers in the <300hz range.

 

[AdamG]

Almost all of Amir's speaker measurements show some portion of the frequency range of of a given speaker to dip to 4ohms and below. Generally it's also in the bass region where more power is needed. I too have concerns about how it would handle the demands of speakers that dip to 4ohms when requiring high power to move woofers in the <300hz range.

It’s not going too, at least not for long. Iirc they only rate down to 6 ohms. So 4 ohms will certainly stress this AVR to its limits.

 

[Technomania]

Plenty of power and well made from the early 2000s. Trouble is, if it doesn't have HDMI, people won't pay a thing for it. Pretty dumb people are.

Hahaha, I like the absurdity of how easily consumers are labelled as "dumb".

 

[AdamG]

Yamaha has always been cheap on their heatsinks. Always. Right from the 1970s when everyone else was using extruded aluminium and highly effective tunnel fins, they were still using inadequate folded sheet aluminium which doubled as chassis reinforcement. I know, I've been working on gear for many decades, and own enough of it.

Only their upper/top models have decent heatsinking. In the 1980s, Yamaha integrateds were stripped down to small transformers, inadequate filter caps, not much more than bare minimum SOA for 8R rated and as I said, those cheap crimped "shark fin" heatsinks- the ones they still use. Plenty of other brands used them too, Luxman, Harman Kardon, etc.

Only into the 1990s on their integrateds did they put a little more effort in, although the heatsinks are still inadequate on all but the TOTL models. Multichannel AVRs need much better heatsinks as they are disippating much more standing (idle losses from bias etc) than a 2 channel amp.

I call it for what it is. The heatsinks on AVRs are absolutely inadequate garbage on the whole. Yamaha even have put thermistors on some bridge rectifiers instead of using adequately heatsinked and rated bridges in the first place. The amplifiers/receivers are designed to shutdown as they simply are not capable of delivering what they promise in the specs.

What a sad assessment coming from you. I laughed when I saw the top down view of the heat sinks! They look like empty matchbooks standing on end. Maybe thinner!

 

[Chrispy]

It’s not going too, at least not for long. Iirc they only rate down to 6 ohms. So 4 ohms will certainly stress this AVR to its limits.

Rating by the manufacturer isn't everything, tho. Doesn't mean it will stress it to its limits necessarily (maybe at very high volume levels). Many avrs do just fine with 4 ohm loads despite no "rating" particularly. Like many 4 ohm rated amps won't necessarily be strained to its limits if used with a speaker dipping below 4 ohm to say 2 ohm (but without a 2 ohm rating). Certainly something to consider if you have high spl/long distance to your seat requirements, tho.