Date: July 04, 1999 10:44 AM Author: julian vereker Subject: AV1 Mathias I am sure that this has been the subject of an old thread, I have checked and there are a number of posts. If you do a search for AV1 (in text) and read the product info on the site, and the following, maybe it will be clearer to you. This time I will put it another way. In most stereo (2 channel) signals there is both 'in phase' information and 'out of phase' information, normally the 'out of phase' stuff is kept to a reasonable level otherwise it diffuses the soundstage*. In the AV1, we take the the 'out of phase' part of the signal, delay it by about 13ms, divide it into two, rotate the phase equally but in the opposite sense to derive the left rear and right rear channels. This put very simply is what happens in any 'surround' decoder, the differences are that in ours, we have full bandwidth rear channels and the maths is 20bit accuracy with the correct level of dither. Hope this helps. julian *(if I was being rude, I would call this american style 'depth' or 'air'). Date: May 23, 1999 09:33 AM Author: julian vereker Subject: Dolby surround The AV1 does a pretty good job of decoding Dolby Surround and it also resolves the out of phase signals in other formats that are not recorded as discreet channels. This can give a very good representation of sounds from behind the audience. It is worth remembering that Dolby 5.1 is a lossy compression system with a data rate of 384Kb/sec for all 5 channels and the sub, this compares with about 1.4Mb for the 2 channels of CD. Maybe a question of less being more. julian PS I seem to remember the AV1 delay is 14ms. Date: October 21, 1998 02:23 AM Author: julian vereker Subject: AV1 The Nait would need to have the pre-amp external power socket fitted and a *CAP used to get the signals out after the volume control. This gets the best results for both music and film, other decoders tend to get connected in the tape loop, but these adversely affect the sound quality to the front speakers when it is in use. julian Date: September 07, 1998 04:07 PM Author: julian vereker Subject: AV1 Hans I use an AV1 with my computer based DVD player, and I don't forsee a problem with any future DVD players, ours (if & when we make one) or others, unless you want to reproduce the rather 'lossy' AC-3 data stream in its 5.1 form. I personally much prefer the 'surround' track decoded by the AV1 than the AC-3 decoded by any of the many boxes that I have listened to. julian Date: July 20, 1998 05:41 AM Author: julian vereker Subject: AV1 "Are there any plans for a upgraded / upgradable AV1?" It is not Naim's normal way to introduce a new product that performs worse than its predecessor, even if it is what the customer wants. We are looking at DVD and AC-3, but the technology has to settle a bit before we can commit much in the way of resources. julian Date: June 10, 1998 01:58 AM Author: julian vereker Subject: digital in Joe, I read with interest all that you say about home theatre, as this is an area which I personally enjoy the end results almost as much as music. We are looking at dvd, ac3 etc. but one of the problems with ac3 is that it is a lossy compression system with only 384Kbits data rate, this may mean that if the whole system is too good one will hear the artifacts of the 'compression'. Also, as yet we have not been able to satisfactorily send and recieve digital audio between pieces of equipment so that it sounds really good at the output. There is much to do, and until it is done, I will continue to use the AV1 for the ambient and rear information and leave the fronts to reproduce un-mucked about stereo. julian PS I don't ever feel deprived of the 'other' channels, even on movies that I have seen in a 5.1 environment. Date: February 23, 1998 04:40 PM Author: julian vereker Subject: the words The AV1 does not process the speech part of the signal and therefore I would suggest you look elsewhere for the lack of intelligibility during your demonstration. Having watched nearly 100 films (from all different sources) on my system which includes an AV1, I have never, with any film or tv programme, had a problem with hearing what the actors are saying, the signal that results from the SFX processing in the AV1 is solely fed to the rear speakers to give a better feeling of the live acoustic (and of course rear occuring sounds). julian Date: January 20, 1998 05:14 PM Author: julian vereker Subject: 5.1 or surround Many of the pertinant issues have been covered in this thread except that so far as I am aware all the LDs and DVDs that have been issued with a 5.1 sound track also have a dolby surround sound track as well. Since Dolby Digital is now the prefered world standard sound encoding for DVD I suspect that this will continue to be the case. I have listened to a full blooded 5.1 sound system with huge Velodyne subs etc (and naim amps) also another 5.1 of lesser stature, and at present I am more than thrilled with my own system with the surround info being decoded using our AV1, I find the vastly more believable front sound stage more than compensates for the slight lack of positional (off screen) sound info watching/listening to Laser Disks or DVD (mostly US NTSC). In my view 5.1 is not a unversal panacea, merely one option which seems to me to work in favour of the speaker manufacturers. julian Date: March 03, 1998 02:01 AM Author: julian vereker Subject: AV1 etc A couple of new points otherwise I feel I am repeating myself, so if you want more info, try 'search'. First, the current CD data rate is about 1.4Mbits/sec for two channels, AC-3 is (I believe) 384Kbits/sec for 5 channels plus sub-woofer, since many people are arguing for a better standard than the existing CD, eg 24bit 96KHz or Super Audio CD at 2.8Mbit/sec/channel, it should be clear that there is a general feeling for increasing the data rates not accepting a massive reduction. Second, one is much less critical of sound quality if one is watching a picture at the same time - and vice versa. The other issues have been covered elsewhere in the forum (I think). julian Date: July 02, 1999 02:16 AM Author: julian vereker Subject: AV1 The AV1 takes its signal from one of the spare signal sockets on a *.cap so that when the pre-amp volume is adjusted, it adjusts front and back together. The AV1 is self powered. I have a 140 and a pair of IBLs for the rear, Paul has a 250 and SBLs - he says better is better even for the rear. julian Date: August 07, 1999 06:19 AM Author: julian vereker Subject: veneers etc Chris All the SBL cabinets are made from MDF and have a wood veneer on both the inside and outside, since the inside is not normally seen a variety of utilitarian veneers are used solely for structrual reasons. We do not have a surround sound pre-amp anyplace in our pipeline. We have been looking at an AV2 with all the surround decoding standards (as well our SFX) incorporated, for us one of the problems is that the initial license fees for the Dolby, DTS, etc are more expensive than the cost of the whole development of the product and therefore unless we can amortise these fees over thousands of units, it doesn't look like a good bet. However, were are trying, and the design format is a unit that can be used as the AV1 in a predominantly music based system (with remote adjustments) as well as in the 'Home Cinema' 5.1 variety of modes. It is likely that all the 'Home Cinema' connections will utilise the common RCA connectors on the grounds that in lossy compression systems they are not going to be the weak link. More info Q1, 2000. julian