Yamaha A-U671 Integrated Amp & DAC Review

[pma]

To what level is relative the value 29dB?

This means gain of 28.18x. 100mV at input gives 2.818V output voltage.

 

[exaudio]

To what level is relative the value 29dB?

Input.

Does that mean the AP feeds the Yamaha's analog line in with a voltage in of 0.1587 V?

I'm assuming that V out is given by

And that you can solve for V in like so

Do I have that right?

 

[miero]

Analog line in is probably fed with a higher voltage (2Vrms maybe?), but the attenuation is done in the integrated amplifier on its volume control.

 

[pma]

What is your point? To measure at realistic input analog voltage level and to set gain to some 7dB by volume pot? Then suggest it to @amirm . He is one ears.

 

[restorer-john]

Shame they couldn't get those "bar" knobs to line up nicely, that's pushing my OCD buttons.

Funny you mention that. I have a Yamaha AS-300 here and the pots are a normal low cost PCB mount plastic D shaft. The loudness pot wasn't aligned properly to the zero position due to poor mounting.

What they do is unusual and adds a bit to the cost simply to have the detent "feel" at the mid position. They have incorporated an additional large diameter circular plate with a notch at 12 o'clock, between the pot shaft and the front panel. A recessed steel sub panel is needed and twin screwed down spring steel "clicker plates" for each control pot.

Compared to the pots in the 70s that had the detent built into the pot-body itself, it's a roundabout way to get the "feel" they wanted.

 

[miero]

Yes, I would be interested how an integrated amplifier behaves at 5W output with input at realistic 2V level of contemporary DAC.

 

[miero]

Also Benchmark AHB2 was tested here[1] with gain of 9.2dB for 5W output.

It would be more fair to compare SINAD of amplifiers with similar gain.

[1] https://www.audiosciencereview.com/...-and-measurements-of-benchmark-ahb2-amp.7628/

 

[mhardy6647]

Shame they couldn't get those "bar" knobs to line up nicely, that's pushing my OCD buttons.

I guess they are rotary knobs, rather than switches, in which case I'd prefer conventional circular/cylindrical knobs, so that they don't look untidy when not lined up.

The vintage Yamahas used the 'pointer' knobs for function selectors, so the alignment wasn't hard if set to their "defaults" Since the function selectors aren't multi-section wafer switches any more, Yamaha took the bold stupid idiosyncratic decision to repurpose their 'signature' vertical knobs to use as tone and balance controls.

"then"
DSC_6689_z by Mark Hardy, on Flickr
(sorry for some ultra-wide angle lens distortion in this photo)

"now"

 

[restorer-john]

Yes, I would be interested how an integrated amplifier behaves at 5W output with input at realistic level.

Traditionally all amplifiers and preamplifiers are measured with the volume control at maximum. No serious numbers are obtained at any other position and nobody would measure at random points just to get a particular voltage out- it makes no sense unless you were looking for worst case noise positions etc.

Amir would be winding all amplifier volume controls to maximum and controlling the input level to obtain the output level he requires for S/N and FR. If he isn't, he's doing it wrong and I don't think that's the case.

Frequency response, noise, distortion, channel balance etc are all often considerably worse at less than full volume positions. The other issue with modern digital volumes is that many can go above 0dB (on AVRs etc), so the traditional hard stop is not there. You have essentially multiple moving goal posts in terms of amplifier gain, attenuation (and possible volume gain), input level and desired output level.

As manufacturers have differing sensitivities, gain and attenuation characteristics, shooting for a 29dB gain is not unreasonable, but if situations where an amplifier is very high gain in the first place, attenuating may put the product at a disadvantage. Same can be said for low gain products where boosting the input above what is a "realistic" level could advantage them unfairly. But at just 5W@4R (4.47V) out, it's not really a big problem and the numbers will be hardly different.

 

[restorer-john]

Yamaha took the bold stupid idiosyncratic decision to repurpose their 'signature' vertical knobs to use as tone and balance controls.

To their credit, it's hard to follow up the design-award winning 1970s classics, while at the same time keeping the products looking modern and fresh. I think they paid adequate homage to the past and presented a clean-lined looking range and interpretation.

It was good enough for plenty of other major brands to copy/revisit. I mean, look at Onkyo/Denon and even Sony, they all have essentially copied the wildly successful Yamaha neo-classic re-design.

 

[amirm]

Does that mean the AP feeds the Yamaha's analog line in with a voltage in of 0.1587 V?

AP doesn't do anything by itself. But yes, more or less. I set the gain to 29 dB (or close to it) and then adjust the input level that gives that provides 5 watts. That makes them have similar gain to power amps so it is a more even comparison.

Before John complains, I have tested many amps at different gain levels and difference is small (1 to 2 dB or so). So it doesn't change the rankings hardly at all.

 

[amirm]

Also Benchmark AHB2 was tested here[1] with gain of 9.2dB for 5W output.

It would be more fair to compare SINAD of amplifiers with similar gain.

[1] https://www.audiosciencereview.com/...-and-measurements-of-benchmark-ahb2-amp.7628/

When power amps have multiple gains, then I have to pick something. Laster in the review I do show the effect of other gain settings:

As I mentioned above, the difference (green and red) is small.

 

[restorer-john]

Before John complains, I have tested many amps at different gain levels and difference is small (1 to 2 dB or so).

John already acknowledged that in his post.

 

[Francis Vaughan]

Some poorly designed amps may see issues with inter-stage loading or poor gain staging that become evident when the level control is wound up. Overall I would say such a design deserves what it gets in measurements.

 

[Count Arthur]

To their credit, it's hard to follow up the design-award winning 1970s classics

I first got into proper-ish hi-fi in the late 80s and in the UK, less was marketed as more - no tone controls or graphic equalisers that might degrade the sound. The Japanese brands, Sony, Aiwa, Yamaha, etc. were covered in knobs and lights, whereas the British stuff, Naim, Creek, Audiolab, etc. would generally have an on-off swicth and two knobs, one for volume and one for input selection.

My first amp looked like it was built in a shed by someone that wore a cardigan; it may well have been:

 

[restorer-john]

Some poorly designed amps may see issues with inter-stage loading or poor gain staging that become evident when the level control is wound up. Overall I would say such a design deserves what it gets in measurements.

With many integrated amplifiers sporting high gain, high impedance power amp stages and the ubiquitous CD/Pure Direct switch, along with high value volume pots, the FR deviations can be significant down the pot range. Some products I find perform better with the active tone stages switched in due to better stage matching.

Also our friends at Yamaha have a number of products where the line input front ends can be overloaded quite easily, an issue surely not seen since the days of 150mV sources and BCD (before compact disc). As for the phono overload, let's not speak about it.

I am hoping the 2.2V "or more" is a lot more. I have one here (AS-300) to test. This is what happens when input switching is passed off to logic driven "input solutions"

 

[Soniclife]

Here are the specs for the A-S501 in case Yamaha are using the same EQ section for all of the amps that look like this:

Bass
Boost/Cut (20 Hz): ± 10 dB
Turnover Frequency: 400 Hz

Treble
Boost/Cut (20 kHz): ± 10 dB
Turnover Frequency: 3.5 kHz

Are those frequencies common? What are the common range of these frequencies?

 

[infinitesymphony]

Are those frequencies common? What are the common range of these frequencies?

Maybe common for Yamaha? They're really all over map. I only went digging because my initial guess for Bass/Treble tone controls was that they would be somewhere around +/- 10dB at 100 Hz and 10 KHz. With Yamaha's settings it looks like they might function as wide high and low shelves.

 

[Soniclife]

Maybe common for Yamaha? They're really all over map. I only went digging because my initial guess for Bass/Treble tone controls was that they would be somewhere around +/- 10dB at 100 Hz and 10 KHz. With Yamaha's settings it looks like they might function as wide high and low shelves.

Around 100hz was more like I was expecting for the low end. The high frequency is around where I thought it might be.
My amp has adjustable settings for frequency, I think it defaults to 80hz and 2k.

 

[mhardy6647]

Are those frequencies common? What are the common range of these frequencies?

Are you asking abou the tone control characteristics?
I would opine (and that's all that this is, an opinion based on anecdotal information & memory!) that they're not uncommon, although the range is (or may be) somewhat more subtle than tone controls of the old days (to wit, the 'seventies). The turnover frequency is on the high side, though, similar to the old days' typical tone controls.

Since I just happened to look this up yesterday for a tone control question Someplace Else Here's a pretty typical, slightly high-ish-end tone control scheme for Yamaha's ca. 1978 CR-2020 receiver. This one has two different turnover options: 500 Hz (pretty typical) and 125 Hz (more subtle and 'audiophile', with respect to this component's era). This graph (from the owner manual, and I apologize for the quality of the reproduction) shows the maximum range of the controls -- which is pretty unsubtle.

Note that this receiver also has a boost/cut "Presence" (midrange) tone control as well (and for better or for worse).

CR-2020 is on the right in this glamour shot of two almost-super-receivers from the mid/late 1970s

Semi-monstrous 1970s soiled state receivers by Mark Hardy, on Flickr
(as befits the stature and maturity of these two grandes dames, this photograph was taken with 35 mm film ).

Yamaha made up for their fairly ordinary tone controls, to some extent, by offering a variable loudness control in most of their components for quite a few years. The variable loudness was (is), arguably, more useful in the real world. But, again, that's just an opinion, too!