To SAM or not to SAM, that is the question ...

[derekcohen]

As a new user of an older Expert 120, now with a successfully sorted Supex into phono set up, and also streaming Tidal via a Cambridge CXN v2, I am looking at a preferred firmware. 

The Devialet arrived with 7.1.1 and I have now loaded 7.1.3 - it is too early to make a decision, however the choice of firmware also impacts on the availability of SAM.

Speakers are Kef LS50 Metas, and these are supported with the Kef KC62 subwoofer. The issue is that SAM is not available for the Metas under 7.1.3, and only from 8.0 (for me this would be 8.1.3, which I have access to, and which appears to be the next choice to 7.1.3 for most).

I know that testing is now indicated (after all, it is my ears), but I was wondering whether anyone would comment on ...

1.  Using SAM for LS50 (not the Meta version) with 7.1.3. In other words, would SAM work in a close manner with the Metas?

versus

2. Using SAM for LS50 Meta with 8.1.3. What are the expected pros and cons?

and

3.  Whether the KC62 (or any subwoofer for that matter) could be expected to fill in the detail offered by SAM (and not merely extra bass)?


Regards from Perth

Derek

[David A]

I do n't know if there is anyone who can give you answers to your specific questions. For a start and just considering your first question, you would need someone who has tried the LS50 Metas with the SAM profile for the LS50s while using 7.1.3. Most users probably update their Devialet firmware regularly as it comes out. The LS50 Metas are relatively new speakers and 7.1.3 is an old FW version so the chances of finding someone with LS50 Metas who is still using 7.1.3 is low. The chance of finding someone in that boat who tried using the old LS50 profile with the Metas is even lower, most people use the profile for the speaker model they have.

You've got a better chance of finding someone who could answer your second question, that just requires someone using the Metas with the right profile and FW 8.1.3 which, while old, is not as old as 7.1.3.

Your 3rd question is the one which I'm going to take a theory based go at answering, along with giving some kind of response to your first question.

We've got very little understanding of just what SAM does apart from some rather basic comments from Devialet. The core of what it does is to provide phase correction for the speaker's response below 150 Hz. If you go looking in Stereophile's test reports online you can probably find reviews for both the LS50 and the LS50 Meta which include a phase response plot in the test measurements. There are probably going to be differences because there's a number of years between the 2 models, there may be physical changes to the woofer design and there probably have been changes to the crossover design because of the changes to the internal damping of the cabinet. Those changes would be expected to have an impact on the phase response of the speaker below 150 Hz so the corrections SAM applies would be different.

Now add in a sub. For a start the sub, whatever it is, is going to have a different phase response to your LS50 Metas and there's no SAM profile for any sub. I don't know whether, if you're using the sub out facility on a Devialet, just what Devialet do with SAM below the crossover frequency you set for the sub. Does the amp just pass through the signal below the crossover with the SAM corrections for the speaker still present or does it pass a signal without the SAM corrections to the sub? I simply don't know and I can't remember ever seeing any comment from anyone about that.

In any event I think we can safely assume that there will be differences in the sound quality whether you're comparing the LS50 profile to that for the LS50 Meta without the use of a sub or with the use of a sub and, if youre using a sub then your choice of crossover frequency is also likely to make a difference.

How different will depend on just how much difference there is in the phase response of the 2 speakers over the range SAM corrects. Let's say you can find someone who has tried using the LS50 profile with the LS50 Metas. They will be able to tell you what differences they heard and which profile they preferred BUT you have no idea how reliable that report will be for your users. Different people have different preferences when it comes to sound quality, preferences that depend to some degree on their musical tastes. Let's say you like pop music with deep pounding bass and the person giving you an answer happens to listen to classical string quartets or vice versa. You're not going to be listening for the same things and you are going to be chasing very different bass responses for your music. The 'cello, the bass instrument in a string quartet, only goes down to around 65Hz while electric bass goes down to 4 Hx, bass drums can go lower, and synthesisers can go down to below 20 hz. If you want to rely on someone's comments on bass response you need the comments of someone who likes and listens to the same kind of music as you do, with the same kind of sound quality preferences as you have, and ideally with speakers like the LS50 models you want someone who listens in a room of similar size as yours and at a similar listening distance because that is also going to affect the bass response they hear considerably.

Also, note that up until now I haven't mentioned the % level you apply to SAM. Jim Austin reviewed the 140 Pro in Stereophile and tried SAM with his speakers. He found the level made a difference to his resultts and it seems that at a level of 40% or higher if I remember correctly, it was apparently strongly exacerbating a modal response in his room causing problems such as window rattling. Different users with the same speakers do seem to have different preferences for the SAM level setting and different rooms have different modal responses. That throws in another relevant set of factors which will impact on the results and on listener response to those results.

Sadly in audio there are questions which simply do not have a definitive answer and the questions you have asked fall into that category. Really the only reliable way of finding out the answer to your questions is to try the experiments for yourself and they're not too hard to try, all you need is 2 SD cards with different configuration files, one with the LS50 SAM profile and one with the LS50 Meta profile but I have to add a warning. Using SAM increases the woofer excursion in the speaking and excessive excursion creates severe distortion and may even damage the woofer. SAM profiles include some kind of roll off strategy to limit woofer excursion but the limits are based on the speaker used for the profile. The excursion limits for the LS50 and LS50 Meta may well be different and I have no idea which profile would start rolling off first with your speakers so my strong advice, if you want to try the 2 profiles for yourself, is that you lower the volume to very soft before starting to play music, increasing it gradually and listening for problems as you go plus you set the SAM level to zero which will give you the phase correction without any added bass extension and only start increasing the SAM level once you've established that there's no problems with excessive woofer excursion at your preferred listening level because increasing the SAM level is going to increase woofer excursion even further. Basically playing with profiles for a speaker which is different to the speakers you are using comes with an increased potential for speaker damage so if you're going to do it then be very careful about how you go about doing it.

My recommendation is that you use the SAM profile for the speakers you have and, if there is no profile for your speakers then you forget about using SAM until such time as Devialet add a profile for them or you change your speakers to a model for which there is a profile. When it comes to using SAM when you're supplementing your speakers with a sub my feeling is that it's probably not worth it. With a speaker like the LS50/LS50 Meta you're probably going to be setting a crossover frequency up around 80 Hz or higher which is 1 octave below the upper limit of SAM's operation and most of what SAM does is going to be towards the lower end of the speaker's response so what SAM is going to be doing for your speaker is going to be limited and I have no idea of what Devialet do with SAM below the crossover frequency for the sub but they don't have corrections for subs anyway so if the profile is still being applied to the sub then it's not going to be delivering the appropriate correction for the sub anyway.

All of the above is pure opinion on my part. As I said, I haven't tried doing any of the specific things you've asked about but I also think you will find it difficult to find anyone who has tried the specific things you're asked about. If someone here has tried one or more of those things and can give you an answer then I'd give a lot of consideration to their answer but I'd also like to know if, at the very least, their musical tastes matched yours, what SAM level they were using, and whether there was any significant difference in the volume and dimensions of their room to your room because all of those things are relevant to interpreting their comments and how they might relate to your own specific situation.

[Ecki]

SAM is marketed as a key feature for Experts and i don't know a single "expert" who wouldn't praise it.
Any measuring curve including SAM shows significant enhancements, speaker protection included.
So, chances are very high that you will profit from SAM, possibly extremely => by all means, take time and test it.


My experience with first generation expert and SAM (Firmware 10.1.0, anyway the final release for these):

Picked my D200 for a test session in a local studio. A handful of speaker models in a price range up to ~10k€. The D200 was equipped with a std sd-card, i.e. no special eq, no SAM and dynamic power management (vs. fixed, do not remember the correct term). There was a clear winner, it sounded so open/airy, big stage, unheard level of resolution compared to the old speaker ... and really loud (pour studio guy!), no sign of distortion or limiting.

The same speaker pair at home, but now also with a set of sd-cards, including dedicated SAM config (exact match for model) plus dynamic/fixed power control.
As the speaker have to "fill" a lot of space i tend to listen louder, and if i'm alone at home, very loud (pure pleasure!).
Soundwise we did not recognize the speaker ... in a bad way. It sounded strangely worse and volume was very limited (guess due to speaker protection).
We also reduced SAM level from 100% downto 0% to no significant positive effect.
In the end we used the non-SAM sd-card ... and the speaker "shone" again.

Possibly i will harm the speakers by dismissing SAM, but there are no audible negative effects at higher volume, and i cannot imagine a single person that would prefer the SAM way in my home system.

[Jean-Marie]

I am positive that if you configure an pre-amplified (pre-out) output in the Devialet, it is passing the signal before any SAM processing.

In addition, as said above, SAM action is mostly in the low frequencies which are typically the ones handled by the Sub and that would be already filtered out towards the speakers.

I seems to remember that at one time (maybe it is still the case) you could not have SAM activated together with Sub pre-out, but anyway I would posit that with a sub, SAM is much less important than if you have a configuration without one.

My two cents,

Jean-Marie

[JohnnySix]

My only observation of SAM is that other than the (optional) bass increase, even at 0% I think it improves the solidity of images at the periphery of the soundstage in the highest quality recordings. However, its very subtle and I have gone long periods with & without it. The fact that I use two KC62 subs has largely removed the need for SAM, and avoids all the ridiculous EQ & Crossover bugs that come along with SAM.

[Delija]

Sub configured/optimized without SAM cannot be used with SAM - because the phase is shifted. It will be totally off.
Also, sub optimized for SAM percentage X, won't work well with SAM percentage Y.

If your sub has presets (like SVS) you can configure several presets for different SAM configurations.

[ogs]

I'd go straight to fw 10.1.0 and load SAM for the LS50 Meta. If you do not enjoy that a KC62 sub (or two) should do it. If using a subwoofer SAM should be left off as there is no independent line out on the 120 and you must use the speaker level input on the sub. There used to be a SubPreOut board option for the 120. Maybe your 120 have the board installed?

[derekcohen]

I'd go straight to fw 10.1.0 and load SAM for the LS50 Meta. If you do not enjoy that a KC62 sub (or two) should do it. If using a subwoofer SAM should be left off as there is no independent line out on the 120 and you must use the speaker level input on the sub. There used to be a SubPreOut board option for the 120. Maybe your 120 have the board installed?

I am tempted to do this. 

As David wrote, and as I anticipated at the start, there are few, if any, who have had all their planets aligned to know these answers. 

It only really occurred to me yesterday, when installing 7.1.3, that SAM was not being activated for the LS50 Metas. The sub was hooked up, and the sound was great. I could live with it, but do wonder what to do to make it better still, which is possible owing to the many permutations available. It got me thinking that LS50 cannot be that different from LS50 Meta. Still, I will be patient with this. I have posed the question to Devialet, and will post their reply when they will get back to me. 

The Expert 120 I have did not come with a pre-out board. Rats. This is not that big a deal since one school believes that the best way to hook up a subwoofer is from the speaker out plugs on the amp. In the case of the KC62, it is powered by 2x500 watt amps internally, and these require a minimal amount of power to drive them. This is how they are set up, and the loudness and cutoff is set at the sub. 

Since I have not actually experienced SAM, I am now more curious than ever to find out what it is all about. Perhaps 10.1.0 would be interesting - I have a few extra 2 Gb SD cards. I can switch off, then on, the KC62 and hear the differences. I am also curious to know if anyone has used SAM on LS50s or LS50 Metas, and decided that a sub was no longer needed?

Thanks all for your contributions so far.

Regards from Perth

Derek

[ogs]

@derekcohen Then you have the KC62 dialled in already!
Easy to find out if what SAM does on Metas alone is sufficient or not. Loading 10.1.0 will also let you hear the difference to 7.1.3. I wouldn't bother with 8.x and 9.x now. Maybe later if you feel like it.

[Jean-Marie]

If you are using the speaker level entries for your Sub, then it is really a bad idea to use SAM, because your sub will be fed with the electric signal calculated by SAM according the the characteristics of the speakers and not at all adapted to your sub.

Jean-Marie