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Offline Martin Colloms  
#21 Posted : 18 March 2015 13:43:04(UTC)
Martin Colloms


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quite right ....

it comprises an overview of the D technology and the progress made with the amps over the years since introduction

there is a detailed sound quality check before doing SAM evaluations for four speakers.

SAM is also introduced with discussion of group delay and phase correction, and practical corrected waveforms and their sound quality implications....


All very interesting, and promises to be controversial.

Martin C

Offline Martin Colloms  
#22 Posted : 26 March 2015 20:43:33(UTC)
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New issue vol 9 no 1 Jan -Mar on the presses!

should be mailed out early next week

packed full of stuff, even we are impressed ......

MartinC
Offline Martin Colloms  
#23 Posted : 28 April 2015 18:05:31(UTC)
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I am really surprised that there was so little reaction

some expected smearing of yours truly on the D supporters site but not much reasoned discussion on the pros and cons....

I was primarily interested in SAM as I have an ongoing investigation on group delay and its audibility, and the correction was subtly audible in good operating conditions , the D amplifier notwithstanding.

The value proposition is quite reasonable, even if it does not work quite as well as advertised,

it is highly puffed and the new loudspeaker even more so.

I feel that this degree of puff may well be disbelieved, and discredit much of the good work.

It did quite well for a hybrid Class A/D with a switch mode power supply, much better than the batch I did a few years ago.

Much of it was Hi Fi but if your taste was towards good rhythm and timing , here it was not so strong.........( in my opinion)

Martin Colloms

Offline Togil  
#24 Posted : 01 May 2015 07:19:45(UTC)
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I think the article didn't put enough emphasis on the slightly " mechanical " quality of the sound which is its achilles heel in my view; it was already most apparent in Munich on the Magico Q1s two years ago when many reported the poor sound. Last year they used B&Ws and turned down the volume so it was less apparent. Will be interesting to see what they come up with this time.
Hans
Offline Martin Colloms  
#25 Posted : 01 May 2015 09:20:46(UTC)
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If by mechanical you mean slightly synthetic , even glassy , a micro textured overlay , that is true, but it was not severe and the clarity generally held up well.

Much of the competition of this power and price will not fare much better.

Martin Colloms
Offline HansW  
#26 Posted : 02 May 2015 17:03:34(UTC)
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Martin,
I did very much appreciate your Devialet review. Most reviews have been extremely positive but not very clear about how it measures up to alternatives. It is an impressive piece of kit and technology. The compact packaging is also very attractive.
I have heard it a few times at shows and at a dealer ( through Magico speakers) and have not been convinced. Clarity yes, but not convincing in terms of body or weight; it has sounded thin and digital sounding. I am experienced enough not to rely on short listening sessions in unfamiliar environments so your comprehensive review provided perspective and confirmation of my impressions. The sound quality rating really helps in interpreting the words of a review.
Would be great if you can review the Phantom also. Again a very impressive product and one that could work well with a flat screen TV.

Best regards
Offline YNWaN  
#27 Posted : 03 May 2015 10:13:03(UTC)
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Sorry, I haven't posted for some time, but Martin's Devialet review has prompted me to do so.

I subscribe to Critic (and generally enjoy it very much :)) and so read the Devialet review when it was published. At the time my response was to appreciate how thorough it was and also the structure - amp review first and then SAM review - the additional measurement and technical information was also very welcome. I thought it came over as a well considered article and certainly didn't think that it was a negative piece of writing or particularly critical of Devialet. However, on subsequently reading some of the comments on the forums I more regularly frequent I realised that some Devialet supporters (though frankly some of these supporters strike me as having very industry biased views) had interpreted Martin's review as a damning critique designed to quash interest in the brand! It would appear that, for some (certainly not all), if one is not 100% pro Devialet one is 100% against!

Personally, I'm not anti class D at all and even have such an amp in my system. A Lab.gruppen IPD 1200 powers the woofers in my 3 way speakers. Not only is this class D, with a SMP power supply, but it also has a digital front end that allows the amp to behave as a fully adjustable digital crossover allowing both active drive of the woofers and response shaping of the output to overcome room modes. The mids and tweeters are passively driven by Naim amplification. Given the current structure of my system I must admit I feel quite drawn toward the benefits of SAM - or similar application of.

Regarding class D; well I have tried running my speakers full range passive from the Lab.gruppen but whilst I was struck by the grip and control (immediately obvious) I was not so 'wowed' by the lack of air and generally rather dry quality to the upper mids and highs. I also found the presentation a touch flat in terms of stereo focus and depth (my Naim gear is not entirely standard). I also recently listened to a pair of Hypex Ncore amps and felt similarly about them with regard to how I found my Lab.gruppen when used full range.

Edited by user 18 May 2015 15:54:10(UTC)  | Reason: Far too many T's in Martin - now removed.

100% analogue
Offline Pete_w  
#28 Posted : 03 May 2015 11:10:32(UTC)
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Off topic, but my switching amps (T-amps) sounded pretty unimpressive when I first used them. Gritty, hazy and a bit confused, albeit with good timing. Better than the DIY Naim-clones I'd been using before, but that's not setting the bar very high[1]. I'd built 2 stereo amps, with the intention of bi-amping. Once I got the second one commissioned, it rapidly became clear that the issue was in some way caused by cross-talk between the two channels which share a low-voltage power rail for the front end. Extensive tweakage to that 5V rail helped to an extent (some Black Gates buried in there!), but couldn't alter the the fact that it was only one shared rail. Once I realised what was going on, I gave up bi-amping and ran them as monoblocks, just using one channel of each chassis, with the second input tied off. Much much better.

So that's the configuration I've used them for the past 10 years, and have been very happy. My old pre-amp didn't have balanced outputs, and there seemed no point trying to contrive a phase-splitter to bridge both channels, and anyway that might just have given me the original problem back. So I just stuck with one channel. When I did buy a pre-amp with balanced outs, I had other things on my mind and couldn't be bothered, it's not like I need the extra grunt.

I just mention this because the comments on the Devialets (and what I've heard myself) are in some ways reminiscent of what I heard from my own amps when I ran both channels. I wonder if anyone's ever tried a pair mono'd but not bridged?


[1] By which I mean my Naim clones weren't very good, I'm not criticising (much) the classic '135 circuit that they were clones of.

Edited by user 03 May 2015 11:11:55(UTC)  | Reason: Let's try writing English...

Offline phil page  
#29 Posted : 03 May 2015 15:21:19(UTC)
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I had posted this elsewhere, but perhaps this is the place for it:

OK I've now read the Devialet review. Martin actually seems pretty supportive for most of it, and the SAM processing. But then he only awarded 37 points, which has clearly upset a few people. I'm sure that Martin is only reporting his findings and his views/opinions. Perhaps the rhythm and timing elements are more important to Martin than to others, but I think to ascribe political or other motives to him is, well, unworthy. Critic may be different from other magazines in some ways, but it is still produced as entertainment for people like us. It isn't a scientific journal. Personal opinions and likes/dislikes are OK. If you don't like that, don't buy the magazine.
Phil
Offline Martin Colloms  
#30 Posted : 24 May 2015 05:22:12(UTC)
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At Munich Devialet showed a little box of tricks which integrates the loudspeaker test system with new Devialet software and an inexpensive laser to measure driver excursion.

They envisage visiting stores and homes to test further models. Operators will need some skill to run the tests accurately.

Meanwhile Linn are rolling out their broader loudspeaker personalization scheme which also includes first order boundary correction for the speaker when placed in preferred

locations.



Martin Colloms


Offline Togil  
#31 Posted : 24 May 2015 07:44:23(UTC)
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The music in the Devialet room was even more Mickey Mouse than in other rooms and the speakers sounded pretty dire.

Hans
Offline Martin Colloms  
#32 Posted : 25 May 2015 11:42:38(UTC)
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I could not bring myself to write how they made fools of themselves in the Phantom dem room , with many pairs on at once all over the place , deafeningly even dangerously loud with not the slightest hint of good quality sound.........

Roll up Roll up it was like a noisy circus

MartinC
Offline Pete_w  
#33 Posted : 26 May 2015 20:19:48(UTC)
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Well, Martin, I've just spent some of the afternoon in the company of one of the lesser Devialets - a 200, I think - as part of the process of sanity-checking whether my admiration for the little Benchmark AHB-2 is misplaced. We were driving PMC twenty.26s with all the amps. My commentary on your review is that you and Chris were too kind. My wife said "warm, but pedestrian". I just felt that it made every single musician we played sound as if the only reason that they'd gone into the studio was that the mortgage payment was due. SAM didn't help. Very pretty, but clearly not for us... It may be that people who listen more to tonality than timing would come to a different conclusion....
Offline Martin Colloms  
#34 Posted : 28 May 2015 08:41:56(UTC)
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Re SAM and Devialet

My interest was academic , to be able to A/B SAM group delay correction on several familiar loudspeakers.

It was necessary to separate the dynamic headroom control from the group delay and that can be done at lower volume levels before control sets in.

For those that care GD correction does improve colouration, bass extension, image perspective and within the limits of the test amplifier , also timing .......

For the review I had to weigh up all the facilities and give some value weighting for SAM.

Some listeners were not that bothered by the Devialet sound , while some were singularly unimpressed by the barely average timing and the weaker dynamic punch, and found the

somewhat monochromatic tonality would allow their attention to wander.

A test case such as this shows how much opinion varies amongst purchasers and reviewers. The vast majority of reviews published fro this amplifier series are overwhelming

positive on every aspect and feature: perhaps some those opinions which might have lent to the negative have not seen the light of day.........., or perhaps some reviewers

have chosen to self censor their work.

Martin Colloms
Offline Togil  
#35 Posted : 28 July 2015 08:34:53(UTC)
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I have only just noticed that Devialet are making some outrageous claims on their website for the bass frequency extension after SAM.
In the ATC forum there is a discussion how an SCM7 could possibly go down to 24 Hz ( normally 60Hz, - 6db ), with a consensus that this is impossible without severe limitations in the performance of the speaker.
Hans
Offline Martin Colloms  
#36 Posted : 28 July 2015 14:55:58(UTC)
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Devialet are technically sound and do not exaggerate

the bass extension gain is not so much that you will hear the bass, if you do turn it up, the SAM programme cuts back the bass boost to avoid overload

What it does is extend the high pass filter function of the speaker to lower frequencies, so that at normal, modest levels you can enjoy the less phasey sound and better timing derived from lower group delay.

This is despite any issues concerning timing per se for Devialet technology

as you wind it up SAM knows the dynamic limits with frequency and keeps the speaker out of trouble

subjectively the speaker will then play cleanly to a substantially higher level

the limiting is transient and is not obtrusive

while gross speaker overload is readily audible

Martin Colloms
Offline kengale  
#37 Posted : 28 July 2015 17:26:50(UTC)
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Originally Posted by: Martin Colloms Go to Quoted Post
Devialet are technically sound and do not exaggerate

the bass extension gain is not so much that you will hear the bass, if you do turn it up, the SAM programme cuts back the bass boost to avoid overload

What it does is extend the high pass filter function of the speaker to lower frequencies, so that at normal, modest levels you can enjoy the less phasey sound and better timing derived from lower group delay.

This is despite any issues concerning timing per se for Devialet technology

as you wind it up SAM knows the dynamic limits with frequency and keeps the speaker out of trouble

subjectively the speaker will then play cleanly to a substantially higher level

the limiting is transient and is not obtrusive

while gross speaker overload is readily audible

Martin Colloms


I well-remember some active Hi-Fi speakers which had exactly this function built in. Can't for the life of me remember the make/name, but they weren't expensive and were I think made abroad. They used feedback around the bass units to enable small cabinets to be used.

The active speakers I designed myself had a similar arrangement - with active crossovers and separate PA's for each frequency band, I incorporated peak-limiting compressors in each band. This was just for speaker protection, they weren't intended to be played this way. The HF band also incorporated a long time-constant compressor to take into account the differences between the peak and thermal limits of the tweeters I was using (T350's).

Offline Martin Colloms  
#38 Posted : 28 July 2015 17:48:11(UTC)
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there was a small fashion for super compacts with large bass drivers in well undersized enclosures

-3dB at 120 Hz , except with the on board active amplification 120W per bass driver, it was force equalized flat to 35Hz .

Swings and roundabouts , those , that I heard sounded a bit forced and compressed in the bass.



You may be recalling the KLH compacts which had unconscionably deep bass achieved with a line level active dynamic equaliser .

Lots of lift at lower levels for incredible deep bass and then dynamic cutback to protect them with peak programme levels

you could hear the limiters pumping and it died a death .

Martin Colloms
Offline kengale  
#39 Posted : 28 July 2015 22:18:20(UTC)
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Originally Posted by: Martin Colloms Go to Quoted Post
there was a small fashion for super compacts with large bass drivers in well undersized enclosures

-3dB at 120 Hz , except with the on board active amplification 120W per bass driver, it was force equalized flat to 35Hz .

Swings and roundabouts , those , that I heard sounded a bit forced and compressed in the bass.



You may be recalling the KLH compacts which had unconscionably deep bass achieved with a line level active dynamic equaliser .

Lots of lift at lower levels for incredible deep bass and then dynamic cutback to protect them with peak programme levels

you could hear the limiters pumping and it died a death .

Martin Colloms


I wonder what you'd make of the system I'm working on at the moment:

Drivers (x2) 900mm dome, 100mm throw, mounted at opposite ends of a 1m tube enclosing all the electronics
PA (x2) 60kW, 25Hz - 250Hz class D
Active closed-loop system with feedback directly from the driver position.

Sound levels (underwater) - enormous! We have to ramp up the sound levels over 3/4hr to allow sea mammals time to flee the area.


Offline Togil  
#40 Posted : 29 July 2015 05:44:26(UTC)
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"I wonder what you'd make of the system I'm working on at the moment:

Drivers (x2) 900mm dome, 100mm throw, mounted at opposite ends of a 1m tube enclosing all the electronics
PA (x2) 60kW, 25Hz - 250Hz class D
Active closed-loop system with feedback directly from the driver position.

Sound levels (underwater) - enormous! We have to ramp up the sound levels over 3/4hr to allow sea mammals time to flee the area. "



Are you looking for MH370 ?

Edited by user 29 July 2015 05:46:56(UTC)  | Reason: Not specified

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