Apologies if this has been answered somewhere before, but when Devialet specify that effect SAM has on a speakers absolute bottom end is there any information on how they arrive at the result? Normally a speakers specs are quoted as +/- 3db. I think i recall reading somewhere that they may be quoting their numbers at +/- 6db...
(06-Apr-2015, 01:45)wikeeboy Wrote: [ -> ]Apologies if this has been answered somewhere before, but when Devialet specify that effect SAM has on a speakers absolute bottom end is there any information on how they arrive at the result? Normally a speakers specs are quoted as +/- 3db. I think i recall reading somewhere that they may be quoting their numbers at +/- 6db...
I presume you mean whether the bass response is quoted as the -3dB or -6dB point, not what you actually wrote.
They have not, as far as I have seen, made that public. OTOH using DSP correction for the bass the -3dB and -6dB points will probably be very close in frequency, since the fall off at the end of DSP correction will plummet!
Sorry for being confusing, yes i should have typed -3db or -6db.
There has been some discussion over at Stereo.net.au about Devialet and it's wild marketing claims. The claim that Phantom is the best sound in the world and 1000 times better than anything else unfortunately tarnishes the entire Devialet brand and is just ridiculous marketing hyperbole.
With regards to SAM. i have tried it on several speakers and like what it does, but i am just trying to understand how they are measuring bottom end extension. Surely they should only use the widely accepted -3db rating like most speaker manufacturers do, otherwise they are just inflating things. Showing a speakers can do 25hz isn't really saying much if its down -10db, surely?
Well I don't pay that much attention to bass specs, since the room and position in the room affects the bass frequency response more than the speaker itself.
I had always thought that the standard bass data was -6dB relative to the level at 1kHz, but even then speakers have a very uneven frequency response compared to electronics, and depending on the FR trend of the speakers in question the difference between a -3dB point and the -6dB point is academic and almost meaningless to anybody who knows anything about acoustics.
Imagine a speaker with a 6dB bass hump, there are plenty about, then, looking at the decline of bass response curve the level will have to have dropped 9dB before it is -3dB relative to 1kHz. A really good speaker with even bass response will only be 3dB down its decline ramp at the same spec.
I hope a lot of the ridiculous Devialet marketing puff is poor translation. The 5000x better is probably distortion at 20Hz, which is likely to be true, since very very few speakers can go down to 20Hz, and will have no DSP correction in the bass anyway. 10% distortion is pretty common at the low limit of traditional speakers.
I have written that the Devialet web site is pitiful nowadays several times. Back when I became interested by the technology the web site gave good technical information was simple and easy to navigate.
Now the web site is almost impossible to navigate with stupid or missing links, and there is little or no complete useful technical information about any of the products.
It all went screen candy and no data after the bloke who owns Louis Vuitton invested, IMO. They seem to think the future lies in attracting brand-whores who are content to wear the Devialet tee-shirt rather than technically interested audiophiles.
Maybe they are right, there are certainly far more brand-whores than stereo buyers, particularly amongst youngsters.
(06-Apr-2015, 01:45)wikeeboy Wrote: [ -> ]Apologies if this has been answered somewhere before, but when Devialet specify that effect SAM has on a speakers absolute bottom end is there any information on how they arrive at the result? Normally a speakers specs are quoted as +/- 3db. I think i recall reading somewhere that they may be quoting their numbers at +/- 6db...
I am almost certain that they are using a -10dB figure.
I am basing this on their figures for my speakers - Magico S1's.
Quoting from a post that I wrote on Stereonet :
"I think that part of the reason that Devialet's claims for SAM appear so inflated is that they do not give any reference point.
However, if they are claiming that the un-SAMed Magico S1 speakers go down to 30Hz, then it seems that they are using a -10dB reference point. The un-SAMed S1's are flat to around 48Hz, around 42Hz at -3dB, around 35Hz at -6dB and around 29dB down at -10dB.
These figures are as I read them off a graph published by the German "Stereo" magazine.
SAM is the real deal and I feel that there is no need to claim over-inflated results by using unstated -10dB reference points as it only undermines their achievements."
Devialetchat members that have SAMed speakers that also have a published frequency response graph can check Devialet's claims against the graph.
Per manufacturers figures, the KEF Blades are -28Hz at -6dB. Devialet's figures are 24.6Hz without SAM and 14.4Hz with SAM. So for sure, in this case it looks like Devialet's numbers are quoted at something lower than -6dB. Maybe -8dB? Interesting stuff, and more evidence of Devialet bigging things up 1000 times more than normal manufacturers. However, if it sounds ok, its all fairly irrelevant I think, especially as some of the LF numbers for SAM'ed speakers are actually in the subsonic / inaudible range!
(23-Apr-2015, 13:00)gray Wrote: [ -> ] (06-Apr-2015, 01:45)wikeeboy Wrote: [ -> ]Apologies if this has been answered somewhere before, but when Devialet specify that effect SAM has on a speakers absolute bottom end is there any information on how they arrive at the result? Normally a speakers specs are quoted as +/- 3db. I think i recall reading somewhere that they may be quoting their numbers at +/- 6db...
I am almost certain that they are using a -10dB figure.
Hello,
I am not sure of that. For instance with Kef LS 50 : without SAM, Devialet announces 44,8 kHz. Kef site tells 47Hz - 45kHz (-6 dB).
I think they have their own protocol, as their sound pressure graphics : "Measurement realized on Angel by Massive Attack ". Non conventional protocol
!
Best regards,
Sylvain
Devialet announces 36 Hz without SAM for the B&W 683 S2, although B&W rates them at 30 Hz -6dB. On the other hand, they announce 17 Hz bass extension !
I did an experiment by playing a 20 Hz 0dbFS sine wave: the woofers move like they are going to come out the speaker (even at -25dB volume) but basically no sound/vibration is produced. I have to go up to 28 Hz and then the bass become really audible, and at the same time the woofer calm down significantly ! Very strange... Moreover, each time I turn the volume control, while playing the 20 Hz sound, a very weird digital noise is produced, including some "pops" and "ticks" which do not sound very good. Nothing like that happens when SAM is disabled.
Besides that, SAM works very well on most music with the 683 S2, but sometimes I have the feeling the woofers move too much compared to the playback volume/amount of bass produced. Looks like SAM is trying to make them reproduce frequencies they cannot...
I am not sure what you are all trying to prove !!!
(31-May-2015, 15:06)NickB Wrote: [ -> ]I am not sure what you are all trying to prove !!!
Not trying to "prove" anything. Just trying to understand how SAM actually works and its limitations...