God of SINAD vs. reality we get from most available music files

[solderdude]

A really good top notch speaker gets potentially down to 0.5% THD... aka SINAD no better than 46

Even if that were true you have to consider harmonic spread and the fact that, in speakers, the FR is split in more than one drive unit.
With speakers most distortion is 2nd or max. 3rd harmonics and even 0.5% is not really problematic at higher levels in that case.
With electronics having 0.5% THD (at a specific level) there may well be harmonics that are much higher up than 3rd harmonics and those might well be audible in music.

So what, in fact, are we measuring?

Performance of a device at specific levels and circumstances that can give some clues about technical performance. Nothing more, nothing less.
SINAD is just a number that is easily ranked and just one generated number amongst many other generated numbers and plots.
A high value is indicative of a low noise/hum/distortion (opposite a specified level). Low noise, low hum and low distortion is desirable.

It says nothing about how the same device will perform in other conditions such as ground loops, interacting with other gear, in specific circumstances. It also says nothing about tonality (FR only in case of high SINAD) and longevity nor about functionality.

It is too bad a lot of people can not see 'past' the ranking of SINAD and give that table much more importance than it deserves and use it as an excuse to make fun of measurements and their importance. Usually by lack of understanding.

Yes, more measurements etc. would be welcome but then we would not be checking ASR for new reviews every day but at most once every week.

 

[solderdude]

Your own comment on one graph is how well it is performing at only 3% THD @ 30Hz... which unless I am much mistaken, calculates to a SINAD of around 30?.

SINAD is usually measured with a single tone at 1kHz. The F208 is below 0.1% = 60 (at 96dB SPL reference) and thus may well be 'external' noise dominated number.

 

[dlaloum]

Wrong adage. You can do a sloppy job of washing a dish and leaving soap and dirt on it. Or wash it properly. It doesn't cost more to do it right so there is no enemy.

But is it?

A Quad 606 is a great sounding amp - the circuits are relatively simple, and use easily sourced components, and can be repaired without much trouble (or expense)...

The AHB2 achieves legendary SOTA measurably "Clean" results...
But to achieve it you have a high complexity design... which reminds me of many Class D amps...

When you look at audibility thresholds - you have to ask have designs such as the AHB2 gone far beyond what is needed or reasonable for domestic audio?
And to achieve it, has simplicity and easy/simple/economical reparability been sacrificed? (I have the same concern with most Class D amps, although I use them myself!)

AVR's are now highly complex beasts, and a circuit board level fault, outside of warranty, almost invariably results in the unit being junk - there is no reasonable, economical repair option. This applies to AVR's to Class D amps, and (at a guess) to the AHB2.

To my way of thinking, these devices are like Formula 1 racing cars, capable of astounding results, but you probably don't want to drive one of these every day, the cost of an engine rebuild is prohibitive!

One of the things that I always found admirable in Peter Walkers industrial designs, was that he did take into account manufacturing, parts costs, long term maintainability - the designs were not the best that could be achieved at the time... (the Japanese did better... eg: Sansui power amps) - but they were more than good enough - with all the advantages that additionally acrue to a simpler design.

My point is, the SINAD charts go a long way beyond "good enough"... and a lot of people end up focusing on the pointy end of well beyond "good enough".

It draws us into that old "spec warfare" that bedevilled the late 70's through into the 80's - and keeps coming back periodically

 

[MattHooper]

Precisely. BUT it's interesting. If I make 6 versions of a track, each 1dB apart (intensity, not loudness, note), any comparison of two adjacent (in level) tracks will almost always favor the higher level track.

***BUT*** Comparing the highest level to the lowest level may very well (not always, of course) have the listener pick the LOWER level track.

It's not a transitive property.

I've done something like this with compression once. Recorded a small band. Did some modest compression. And a little more and a little more and a little more. The final copies were heavily compressed (though not brick wall limited). I had the musicians listen and pick a favorite. Each step of the way they picked the more compressed one. We took a few minutes to discuss some other things, then I had them listen to the first moderately compressed version against the most compressed. They all made a funny face, and asked what happened to that 2nd version because it sounded all messed up, bad, not really like what they remembered and a few other comments.

Both fascinating posts! Thanks! Reminds me of the frog boiling in a pot....

 

[Blumlein 88]

Something of a wild conjecture. Here are NRC measurements of Revel F12's I used prior to F208s.

THD+N @ 90dB, 50Hz - 10kHz (measured @ 2m)

THD+N @ 95dB, 50Hz - 10kHz (measured @ 2m)

Both are tonally pretty well balanced. The F208 is much cleaner sounding however. Yes, I know ill defined subjective description. And the F208 gets louder with less sense of anything being wrong. Maybe because of the F12 having that peak of distortion in a most bad location due to the crossover?

 

[restorer-john]

It draws us into that old "spec warfare" that bedevilled the late 70's through into the 80's - and keeps coming back periodically

It does return every now and then, but each time with a different twist and people focusing on one parameter to the exclusion of all others. With ASR it's SINAD (THD+N). We've had sheer power, load invariance, wide bandwidth, ruler flat response, S/N, residual noise, crossover distortion elimination, Class A, dynamic power, current capability etc.

Everything goes full circle eventually.

 

[solderdude]

One of the things that I always found admirable in Peter Walkers industrial designs, was that he did take into account manufacturing, parts costs, long term maintainability

One day at Transtec, some representatives of Quad and Nakamichi (in the Netherlands) were at a show hosted at Transtec.
The Japanese made fun of the 'old fashioned' design of Quad gear.
At one point Peter W took a flathead screwdriver out of his pocket. Opened up one of the power amps (really quick) and all boards were easily accessible from both size.
He turned to the Japanese guys and merely said: 'Old fashioned design ehhh.. I'd like to see you take apart one of your devices' and handed him the flathead screwdriver.

One would have to consider modern times though. As much as I like longevity it is a fact that most gear these days (due to SW and limited support/usability over the years) does not usually have a lifespan for more than a few years anyway. Today's customers are kind of used to buying new gear (even if very costly) every few years as long as they gain in functionality, usability and speed over whatever they owned before.

 

[Blumlein 88]

One of the old amps that were always very clean, and transparent sounding with anything I'd heard them powering. Yet the THD and noise specs are good not spectacular. The noticeable thing is the DC to 1.2 mhz bandwidth. The designer said the bandwidth wasn't a design goal. Very fast recovery from overload was a design goal and the wide bandwidth was a side effect of reaching that goal.

I owned one, and it is one of the few amps I wish I had back. I owned Quad ESL-63s when I had it.

SPECTRAL DMA-50 POWER AMPLIFIER

Specifications

POWER OUTPUT :

@ 8 ohms = 80 WRMS @ 4 Ohms = 120 WRMS

BRIDGED 160 WRMS 220 WRMS

OUTPUT POWER P.K. @ 10% Duty Cycle

STEREO

@ 8 ohms = 140 Watts @ 4 ohms = 200 Watts

BRIDGED 450 Watts 260 Watts

OUPUT CURRENT: Limited to 18A Peak

DISTORTION: Less than .1% from D.C. to 100 KHz typically .006% @ 80 WRMS / 8 ohms

BANDWIDTH: D.C. to 1.2 MHz - 3db

RISE TIME: Less than 300 nanoseconds

SETTLING TIME: 500 nanoseconds

SLEW RATE: 1,000 volts/microsecond

INPUT IMPEDANCE: 10 K ohms

GAIN FACTOR: 25 db stereo, 32 db bridged

INPUT SENSITIVITY: 1.2 VRMS for 80 WRMS output into 8 ohms

SIGNAL TO NOISE: 90db unweighted

INPUT / OUTPUT ISOLATION: 80db

CROSSTALK: 70db

DIMENSIONS: 2.5 H x 19 W x 14 D inches

 

[pma]

It does return every now and then, but each time with a different twist and people focusing on one parameter to the exclusion of all others. With ASR it's SINAD (THD+N).

It's a Golden calf here. Praying to the (Sinad) Golden Calf is to me no different from adoration of super cables or golden fuses.

 

[amirm]

It's a Golden calf here. Praying to the (Sinad) Golden Calf is to me no different from adoration of super cables or golden fuses.

There is little help for you then....

 

[Axo1989]

And Amir, are you trying to make my point for me? the charts you posted of the 328Be show THD peaking at around 0.6% above 50Hz...

I hadn't reckoned Amir thought the world began and ended at 1 kHz., but maybe it's true?

 

[amirm]

I hadn't reckoned Amir thought the world began and ended at 1 kHz., but maybe it's true?

Maybe I am an alien put on earth to annoy some of you:

 

[Thomas_A]

In space nobody will hear you. On earth yes.

 

[restorer-john]

One day at Transtec, some representatives of Quad and Nakamichi (in the Netherlands) were at a show hosted at Transtec.
The Japanese made fun of the 'old fashioned' design of Quad gear.
At one point Peter W took a flathead screwdriver out of his pocket. Opened up one of the power amps (really quick) and all boards were easily accessible from both size.
He turned to the Japanese guys and merely said: 'Old fashioned design ehhh.. I'd like to see you take apart one of your devices' and handed him the flathead screwdriver.

To be fair, the Japanese had moved on to (the precursor to) JIS, which was a vast improvement on the ancient slotted screw...

A slightly rigged and stacked challenge wouldn't you say? Especially as everything from 1968/9 onwards out of Japan was metric/JIS...

 

[solderdude]

it was only because the Japanese guys were making fun of the old fashioned look (back in the days)
Nakamichi made some excellent gear in those days but requires a lot more screws to take out and to get access to the solderside one would often have to disassemble the whole thing.
Where as with Quad one removed 2 or 3 screws and had access to PCB's on hinges, very easy to service.

I hate slotted screws b.t.w.

 

[Blumlein 88]

I think the real difference is Quad thought about the need to service gear on their design. The Japanese mostly thought they designed something reliable with no thought beyond assembly.

 

[dlaloum]

it was only because the Japanese guys were making fun of the old fashioned look (back in the days)
Nakamichi made some excellent gear in those days but requires a lot more screws to take out and to get access to the solderside one would often have to disassemble the whole thing.
Where as with Quad one removed 2 or 3 screws and had access to PCB's on hinges, very easy to service.

I hate slotted screws b.t.w.

It is interesting that it was Nakamichi - as the Stasis amps were a development and derivation of Quads current dumping....

So they would both have been touting different takes on a very similar underlying principle!

 

[restorer-john]

I think the real difference is Quad thought about the need to service gear on their design. The Japanese mostly thought they designed something reliable with no thought beyond assembly.

With respect, that is totally and patently untrue. Pretty much all Japanese gear was designed specifically to be easily dismantled and repaired. I have no idea where people get the idea it wasn't.

Most gear allowed for the front and rear panels to be hinged out and worked on while still connected. They used sliding hinges like this (1976):

Careful service manual documentation describes exactly how to remove key parts or dismantle (1977):

Details on absolutely EVERYTHING, right down to the installation of a headphone jack on this CDP-101 (1982):

The Japanese provided comprehensive documentation, parts and manuals to ensure their products could be easily repaired, unlike much of the US, English and European brands where even getting hold of a schematic was impossible, letalone a proper service manual.

PS Has anyone seen a Topping service manual? LOL.

 

[Blumlein 88]

With respect, that is totally and patently untrue. Pretty much all Japanese gear was designed specifically to be easily dismantled and repaired. I have no idea where people get the idea it wasn't.

Most gear allowed for the front and rear panels to be hinged out and worked on while still connected. They used sliding hinges like this (1976):

View attachment 224432

Careful service manual documentation describes exactly how to remove key parts or dismantle (1977):
View attachment 224435

View attachment 224436

Details on absolutely EVERYTHING, right down to the installation of a headphone jack on this CDP-101 (1982):
View attachment 224437

The Japanese provided comprehensive documentation, parts and manuals to ensure their products could be easily repaired, unlike much of the US, English and European brands where even getting hold of a schematic was impossible, letalone a proper service manual.

PS Has anyone seen a Topping service manual? LOL.

I came to that opinion having repaired a few units. Now the units I've worked on were from the 1980's so perhaps things changed. I didn't say it was impossible. It did seem to me little thought was given to repair. Quad units are very simple to open and work on by comparison as I've repaired a few of those.

Now my day job was never stereo repair. So I've not worked on dozens of units of dozens of models. Just a few of each. Quads were a piece of cake among solid state gear.

 

[dlaloum]

I came to that opinion having repaired a few units. Now the units I've worked on were from the 1980's so perhaps things changed. I didn't say it was impossible. It did seem to me little thought was given to repair. Quad units are very simple to open and work on by comparison as I've repaired a few of those.

Now my day job was never stereo repair. So I've not worked on dozens of units of dozens of models. Just a few of each. Quads were a piece of cake among solid state gear.

My fault for over-generalising,

When I think back on classic gear I have owned... the Quad gear is particularly "repairable/maintainable"...

I also had/have Revox gear and various Japanese components - and in terms of repairability / complexity, I think they were probably much of a muchness

But current trends towards very small, surface mounted components, and a very high density of components, does not bode well for repairability down the line... And the trend towards replacement of entire circuit boards (or entire components) rather than doing repairs, is very very clear.

Started by Motorola in the early 90's after they worked out that the cost, to them, of a replacement mobile phone, was less than the cost of receiving and shipping, in addition to the logistical labour, and the physical repair time combined... in fact it cost them several times the value of a new phone to repair an old one...

Onkyo never even tried to do any component replacement on my failed 2008 HDMI board (which according to many DIY postings, could be fixed by replacing the caps) - they provided me a replacement board.... and some years later when that failed - offered me another replacement board for $900.... (!!) - I feel that this is now the norm.
Other than the occasional greybeards out there.... ( a few of whom are on here) - how many current AV techs/engineers even bother with component level repairs?