First of all thank you for taking the time to measure the H95. Immediately upon seeing the measurements we realized that something was very different to our own. We could not recognize ourselves in the results or in the conclusion.
Please consider this as a manufacturers comment. One where we totally respect the work that has been put down, and peoples views on the product. But where we want to comment the findings, where these does not match our own. So this will typically be our only comment on the issue.
We promised our own findings today. I will therefore present what we disagree on and why.
1) All the DAC measurements are in our mind misleading. They were measured at a level where the amplifier is clipping. In our view, they should be dismissed completely.
1.1) There has been some debate on how we can allow the RCA pre out to be optimized at 550mV, which actually is a fair question. The reasoning behind this is that we mainly see this as a subwoofer connection. Obviously you can debate wether that is a good or a bad choice.
When the pre amp output is more than 550 mV, the speaker output will be clipping and that will influence the performance of the pre out.
The pre-out on the H95 is taken directly from the power amplifiers input stage. See figure below:
When the power amplifier starts clipping, this will reflect in the RCA pre out as well. As such, the RCA pre out can NOT be used as a 2V DAC output. When we measure the DAC performance we connect Audio Precision directly to the output stage of the DAC board. You can of course also measure the DAC on the RCA output, but with a lower setting than 98 and it will include factors from the preamp.
Notes on why;
We used to have a lower output level on the RCA Pre out (earlier models), but since we have 32 dB gain in our power amplifiers we had to raise it to allow for easier subwoofer integration.
Actually we used to run the output from the preamp at a level where it never really started clipping (also earlier models), but on a 60w/pc amplifier consumers did not like to have the volume control at “98” to play loud. And what if you played an old Pink Floyd piece, with low gain… it would never be loud enough.
2) The stability measurement THD + N from ASR claims that the amplifier never reaches stability after warm up.
This measurement is, in our view, wrong. This is how it should look (our own test on AP 2722 today)
We have only almost managed to recreate the ASR measurement if we wiggle the speaker cables in the H95 terminals or tap the output relays.
We disagree with the comment about the power amplifier not being stable. The Hegel output stage is a no-feedback design, and since the distortion characteristics of the power transistor change somewhat with temperature, the total distortion will have a small increase with temperature. In a high open loop gain feedback-design this effect will be much smaller.
3) Distortion measurements in analog mode. These do match ours and are in our minds absolutely fine. We only have some comments.
We could obviously also achieve a super low 0,0001% THD by using lots of feedback. That is a fairly easy design.
But we don’t and the reason is that global feedback amplifiers, in our minds, doesn’t sound very good. Subjective, we take that, but it is our experience. So, we use our SoundEngine to dynamically reduce distortion instead. In the integrated amplifiers the soundEngine is only used in the output stage where we believe it is most important.
Finally, thank you for reading this rather long feedback. I am sure not all f you will agree in our thoughts and comment above. That is fair and it is really what a forum is about. Debating ones hobby.
And if you are ever in doubt, we urge you to visit your Hegel dealer for an audition.
Hegel Music System AS
Anders Ertzeid
VP Sales & Marketing
