Devialet v Benchmark/Parasound/Pass Labs

[Damon]

Damon,

My question was, in fact, a very specific technical question, and the opinion I asked for did concern exactly that and not about sound character and musical expression. ......

Kari

Kari,

Thanks. I understand your original query differently now. I thought that you were going from the purely technical aspects of different equipment to the question of which 'sound' was preferable. You mentioned a possible preference for 'ear pleasing distortion'. Looking at the earlier responses, I wonder if I am not the only one who interpreted your letter that way.

And so in my reply I was simply musing about the differences in musical presentation, and thinking that musicality and accuracy are not necessarily always related (in reproduction). Measurements are interesting to a point, but are not of enduring interest to me, though JA's measurements insert makes a pleasant diversion for a few minutes.

In any event, I think that you are involved in audio at a level well above mine, not least in terms of cost, so your audio exposure and experience appear to be wider than mine as well.

But the comparative discussions are fun, and I'll say that for a small forum, this one has some excellent contributions.

[Confused]

Hi Confused,

Have you tried Dirac room correction? It does what SAM does + more...

Kari

No I haven't. Having said that, I think the thing that gives me a real benefit with SAM is the phase correction. SAM gives an accuracy to the base, and adds a kind of 3D realism to bass sounds, with some music it is stunning. SAM is not just about tone control or equalisation.

[PhilP]

Hi Confused,

Have you tried Dirac room correction? It does what SAM does + more...

Kari

Hi Kari,

It doesn't actually. What it does it very different. SAM aims to ensure that the sound coming from the speaker reflects as closely as possible the signal being fed to it. Dirac tailors the frequency response of the system to compensate for the specific characteristics of the listening room Edit: and impulse response.

Which delivers the better result is a different question. Ideally you need both amplitude and phase correction plus room correction so neither solution is complete.

RegArds,

Philip

[Kari]

Hi Philip,

It is my understanding that Dirac Live do both amplitude and phase correction. It is this feature that makes Dirac rather unique among room correction programs. When I surf into their webpage now it seems that Dirac is developing a similar product as Devialet's SAM with their "Dirac HD Sound". Seems to be oriented towards speaker and earphone manufactures (I just scanned through quickly), but this means that it may very well be developed to a software for the end customers in the future.

thumb5, there is a version of Dirac Live licensed to miniDSP that works with all sources, i.e. it is a box that in one version is placed between digital sources and the dac and in another version is placed after the dac or between a preamp and a power amp.

Kari

[thumb5]

Kari - yes, I'd seen the miniDSP Dirac boxes too, they look pretty handy (actually I researched them a little before buying my Anti-Mode). BTW your comment above about Dirac doing both amplitude and phase correction is what I had understood too.

[PhilP]

@thumb and Kari. Yes sorry, I wasn't clear in what I wrote I was trying to point out that what SAM does is fundamentally different to what Dirac does. SAM is In a way more 'theoretical' in that it tries to make the speaker deliver a 'perfect' response to the input signal (ignoring the environment that it's in) and applies the same modification to both channels. What Dirac attempt to do goes way beyond this.

I will go away and find out more about Dirac

[Kari]

I think that Devialet is approaching the single largest problem within hi-fi, i.e. amplitude and phase errors caused by speakers and room, in the correct way. I hope they continue the SAM project (which corrects speakers) with some sort of room measurement and correction module. For most of us (where the living room is the listening room, limiting choices of speaker positions and negating anything but minor room treatment) it is a fact that the effects of speaker-room interactions swamp all other differences between hi-fi equipment, at least in the high end segment.

Another (than Devialet) interesting example of what some well thought out solutions can do is the Bang & Olufsen BeoLab5; their top of the line dsp-room correction-dac-amplifier-speaker all in one unit. I know that mentioning a B&O product in a high-end hi-fi forum is a proof of being a heretic. However, those who want me burned at the stake have not heard the BeoLab5. Similar to Devialet, B&O is actually one of the most inventive firms in the hi-fi industry. They invented the ICEpower class D amplification (which dominates the class D segment in hi-fi), they were one of the first (I guess) to adopt a holistic view of listening, i.e. a simple all-in-one solution that takes care of every from the signal to the speaker output and room interactions. The acoustic lens technology really works very well. The ingenious, extremely easy to use, room-correction also work very well (the speakers send out tone burst and microphones, that comes out from the bottom of the speakers during calibration, capture everything which then goes into the DSP unit in the speakers). And the BeoLab5 looks really cool in just about any living room...

Actually, the main reason why I have not invested in the BeoLab5 is that they are now rather old and have the first generation of the ICEpower amplification and the treble is not up to par with better class A/AB amplifiers. The day that B&O realize that they can use Devialet modules instead of ICEpower I know what I will do....

Kari

[PhilP]

SAM is certainly an excellent first step but adding effective room correction processing is a much bigger challenge which, I suppose, is why we haven't seen it ... yet...

I think one of Devialet's biggest design advantages lies in the close integration of DAC, DSP, pre and power amps in a single box (from what you say B&O have taken a similar approach). This keeps the signal path very short and obviates the need for multiple interconnects which introduce all sorts of problems - rfi, jitter etc. I wouldn't be keen to add a room correction box to my system and hope that if Devialet do implement such a solution that it will be handled by the existing internal DSP chips.

[Confused]

I think I need to stand corrected! Dirac does indeed claim to offer phase correction. Although as I said, I have never tried Dirac, so obviously I cannot comment on its capabilities. It should be noted that there is a Dirac / Room correction thread on this very forum. If anyone does have any good information regarding Dirac or any other room correction software / systems then it would be good to see this. I had a quick read through the thread, and it left me wanting more decent information and feedback!

I think the point re SAM is that it is done in almost laboratory conditions using professional equipment. I did spend some time talking to Devialet's chief designer about SAM. As well as the obvious sound equipment they use laser scanners to monitor cone movement. The SAM process is also quite labour intensive, taking maybe three man-days per speaker. The phase correction is genuinely real time. So for example, if with a particular input signal the bass driver is reacting too slowly, the DSP model of the speaker will actually provide the signal / current to the bass driver slightly before it actually occurs in the music. (Using the buffering and processing, not time travel, Devialet haven't cracked this one yet.) I have spent some time now with "SAM enabled" speakers, and I can attest that that on occasion it's effects are extraordinary, you can hear the accuracy of the implementation, you can then turn SAM off and hear what's gone.

As I said at the start of this post, I am not an expert regarding the capabilities of Dirac. However, I suspect that when you look at what is involved with SAM and its implementation, then this is going to be difficult to match at home, in particular when you look at the accuracy SAM that can achieve with the phase correction etc. As for room correction, well SAM doesn't do it, so third party software, or good old fashioned room conditioning etc. are all we are left with.

For those with experience of Dirac and similar, keep the feedback rolling in. It's an interesting topic, and the existing thread covering Dirac on this forum could certainly do with more input from those with hard earned experience.

[PhilP]

...It should be noted that there is a Dirac / Room correction thread on this very forum. If anyone does have any good information regarding Dirac or any other room correction software / systems then it would be good to see this. I had a quick read through the thread, and it left me wanting more decent information and feedback!

Confused,

I just posted a link to an interesting interview with Dirac's CEO on the thread you mention. It might be good idea if further discussion of Dirac continued over there.

Regards,

Philip