Hegel H95 Review (Streaming Amplifier)

[amirm]

BTW, one approach that's promoted there that has NO basis in science or the research that's been done in hi-fi is the use of measurements to listen. I can't believe that's going on there -- it's one of the reasons I wanted no association with that forum (when ASR was being created, Amir emailed me several times to contribute, because of my experience with speaker measurements). But what's being trumpeted as "science" in that regard is nonsense again. I made a video about it.

I never asked Doug to come here let alone write anything for us (or anyone else for that matter). I extended a warm welcome to him once he did show up on his own based on misconceptions I had about him caring about measurements and such. When I realized those measurements were made by NRC and not him, and he actually not caring about them, I put the screws on him in a thread here resulting in him bolting out.

 

[pozz]

It should be clear now how much stupidity and pettiness you'll find in mainstream hifi.

By the way, the SS and ASR linearity graphs are largely the same except that they use different filters and scaling. Not at my computer but someone else could easily extract the data and plot it for comparison.

 

[sarumbear]

Yeah. Nothing.

This:View attachment 168308
is not brighter than this:View attachment 168310

Trust your ears!

If you are younger than 50 years old you may consider having your ears cleaned.

 

[steve59]

I just read the link to soundstage measurements page and am struggling to understand what's wrong with the H95?

 

[amirm]

First of all thank you for taking the time to measure the H95.

Thank you for your participation as well. I have a question about your diagram and feedback here:

The "DAC" output is prior to amplification block. It is capable of going up to 2.4 volt. Why would that stage care that the amplification block *after* it clips? If I cascade an external DAC to your amplifier and your amp clips, nothing happens to the performance of the external DAC. Why is it that by pulling that functionality in, you wind up disturbing the performance of the DAC in the same scenario?

The answer in AV receiver world is that when their amplifier clips, it impacts the voltage rails feeding the DACs and hence the increased distortion. Is that the same here? If so, it is a shame that in a high-end device like this, you don't have independent power supply for the digital/DAC section. Or simple ability to disable the amplifier.

 

[amirm]

This measurement is, in our view, wrong. This is how it should look (our own test on AP 2722 today)

This measurement shows a drop of 4 dB in performance as the unit warms up -- worse than what I showed! Many audiophiles think that by leaving their equipment on, they get better performance. Here it is backward by not an insignificant amount.

 

[MZKM]

This measurement shows a drop of 4 dB in performance as the unit warms up -- worse than what I showed! Many audiophiles think that by leaving their equipment on, they get better performance. Here it is backward by not an insignificant amount.

I think they were mainly addressing the erratic nature shown in your graph, as they mentioned only via wiggling the cables could they achieve it. Is it possible to smooth this measurement?

 

[Human Bass]

77ohm on a headphone output is borderline criminal.

 

[sarumbear]

I think they were mainly addressing the erratic nature shown in your graph, as they mentioned only via wiggling the cables could they achieve it. Is it possible to smooth this measurement?

Why would smoothing matters? It should be as flat as possible.

 

[Human Bass]

The philosopher is historically important but unarguably very weird and arguably (and in fact) complete crap.

Hegel was extremely totalitarian. All his obnoxious talking about geists, and he comes to the conclusion that the state is the will of God on earth.

 

[PeteL]

v

I want to make sure we don't lose the plot here. So much attention is put on the DAC output but there is a real, undisputed problem with the amplifier. Here is how it performs using analog input:

Here is how it performs when you switch the analog input to digital, with nothing else changed:

We lose 8 dB of performance in the form of raised noise floor due to using the internal DAC.

In other words, if the amplifier used precisely as they intend, either with analog input or digital, the digital input takes a major toll on performance in noise department which is far more audible than distortion. This of course impacts streaming to the amplifier just as well.

Company has confirmed the amplifier measurements so what we have is the final word.

I showed the reason for above in my IMD measurements, showing the high noise floor:

So the DAC measurements were definitely investigative and proved the high noise floor of the internal DAC.

For an integrated amplifier and streamer, this is unacceptable. I, and I am sure many others consider digital input to be "cleaner" due to analog path being very short internally, and gains optimized. Yet we have the opposite here.

The job was not hard. All the DAC had to do was be 10 dB better than the amp. Then it would have 0.5 dB impact on its SINAD.

Conclusions
Measuring Hegel H95 as intended, i.e. with analog or digital input producing just 5 watts, produces far more noise with digital input than analog. This is a bad thing in even mass market products. It is really, really bad in the case of a premium product.

I hope Hegel looks at sources of this performance loss with digital input and remedies it. Had it not shown this problem, it would have gotten an acceptable review from me.

But the Dac is measured against a -24 dBSPL reference Tone (which is your zero on your scale), of course the noise floor will show as high. Measure any of the DAC at -24 dB SPL, what do you get as a SINAD?

 

[MZKM]

v

But the Dac is measured against a -24 dBSPL reference Tone (which is your zero on your scale), of course the noise floor will show as high. Measure any of the DAC at -24 dB SPL, what do you get as a SINAD?

Does the Hegel offer input level offsets? If not, then if the digital input is closer to 0dBFS, it’ll get much louder when you switch from an analog input to a digital one, as the volume needs to be at ~95 on the Hegel to achieve the THX 29dB amp gain.

 

[PeteL]

Does the Hegel offer input level offsets? If not, then if the digital input is closer to 0dBFS, it’ll get much louder when you switch from an analog input to a digital one, as the volume needs to be at ~95 on the Hegel to achieve the THX 29dB amp gain.

??? Analog inputs can come at any volume. Offset against a analog source at which voltage do you want? In this case an analog input of 0.157 V correspond to a signal at -24 dBFS We could do the math for an input at 0 dBFS.

 

[amirm]

v

But the Dac is measured against a -24 dBSPL reference Tone (which is your zero on your scale), of course the noise floor will show as high. Measure any of the DAC at -24 dB SPL, what do you get as a SINAD?

So was the analog voltage level. The amplifier volume control was not touched so the internal DAC was producing the same voltage as I fed it analog input.

 

[amirm]

Why would smoothing matters? It should be as flat as possible.

It can filter out the ups and downs that my measurement was showing.

 

[PeteL]

So was the analog voltage level. The amplifier volume control was not touched so the internal DAC was producing the same voltage as I fed it analog input.

Of course, sure, but think about it Amir, for exemple, look at this curve:

And look at the delta between 0 dBFS and -24 dBFS.

Now look at this curve, and look at the Delta btween 0.157V and 2V

You know better than draw conclusions based on comparison that can't compare.

 

[Bogda]

This measurement shows a drop of 4 dB in performance as the unit warms up -- worse than what I showed! Many audiophiles think that by leaving their equipment on, they get better performance. Here it is backward by not an insignificant amount.

Their measurement does not show two big spikes that are present on your diagram.

 

[amirm]

Of course, sure, but think about it Amir, for exemple, look at this curve:

And look at the delta between 0 dBFS and -24 dBFS.

The SINAD in that DAC at -24 dBFS is around 90 dB. It would be transparent to an 81 dB amplifier. Not knock it down to 72 dB. The DAC in H95 does that because unlike the above graph, it has this kind of noise floor:

Now SINAD is around 70 dB and hence the reason it sucked the performance of the amp down. Which precisely makes my point. The internal DAC is way too noisy. Both DAC tests and integrated pipeline of the dac and amp show this.

 

[amirm]

You know better than draw conclusions based on comparison that can't compare.

I was going to say the same to you but doesn't seem know you know better. See the above DAC graph? The last 11 dB of its dynamic range is useless. So -24 dB is not what it seems. It is actually just -13 dB below its max level -- very reasonable and representative of what could happen in music.

 

[Fleuch]

The SoundEngine2 is the basic building block used in all current Hegel amplifiers, giving a high output damping factor of over 2,000 for the H95 and H120 amplifiers and over 4,000 for the remaining three integrated amplifiers (H190, H390 and H590). Retailers use these figures to suggest that a Hegel amplifier has no problem driving any loudspeaker, and "buy" the company line that the circuit design leads to ultra low distortion. So no difficulty, then, driving a nominal 4-ohm load or less?

The H95 is an "entry level" product into the Hegel range. Looking back over recent reviews, the H95 in the Hegel range is the equivalent of the IO in the Rega range - neither are a credit to the respective manufacturers on the basis of test bench results. In an ideal world the up-market kit from both manufacturers would be available for testing to determine if similar problems are found to be intrinsic to each marque.

Was this a "rogue" sample? or is there an engineering explanation? A digital circuit is really an analogue circuit operating at just two defined signal levels, with timing in those circuits now measured in femto-seconds. When feedback, or feed-forward, is applied around an analogue circuit there must be a time delay between the amplified signal and the feedback (feed-forward) signal arriving at the summing point. If (very) small time delays contribute to distorted performance in a digital circuit, does the same principle apply to analogue circuits? Perhaps this is more critical in the SoundEngine2 circuitry used by Hegel.

Reviews in the consumer media are bland, vanilla bland, with the reviewer seldom calling a spade "a spade", making each review little use as a "critical friend". Only individual specifications are provided and very little comparison (if any) between products. In contrast Amir offers test bench results and a "green, amber, red" conclusion based on those results alone. It is a truly independent source of information (with other members such as Wolf contributing similar work in a different part of the globe). The concept that gear is sent for testing is core to that independence, rather than a reviewer being offered an expenses paid trip to a manufacturer's lair. YouTube reviews should carry a health warning!