Re: [SlimDevices: Audiophiles] Squeezebox Touch with two USB DACs
Thanks for all the replies on this subject. I think that we will put together something with switching at the pre-amp stage rather than inside the squeezebox. I think that as a first try we will simply follow Phil's suggestion of two identical pre-amp and switch the input simultaneously with the remote, this seems to fit the bill nicely. We may be able to link the IR receivers of the two pre-amps to avoid the "remote signal only detected at one pre" problem. Jack. -- jackocleebrown jackocleebrown's Profile: http://forums.slimdevices.com/member.php?userid=10623 View this thread: http://forums.slimdevices.com/showthread.php?t=87592 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/mailman/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Squeezebox Touch with two USB DACs
earwaxer9;631313 Wrote: > Brings me back to the days when audio kit used to be compared in the A-B > type fashion. Sales people had the time and the inclination to go > through the stuff they had and try to find a match that fit your > pleasure. > > Looking back, I'm not sure I would trust the A-B comparison now even if > it was still available. I need more time. I can tell "differences" with > quick comparisons but it would be hard to choose between good high end > kit using that method. With lower end stuff it works pretty well > because you are choosing based on what flaws you are willing to > tolerate the most. You are quite right to be a little suspicious about A-B switching. In my experience it makes some types of difference between the speakers very easy to spot, for example changes in frequency response become very obvious - as do dispersion changes (given the right track and room). However, it encourages the listener to evaluate the speakers in small chunks of 5 to 10 seconds and this can be misleading. If I listen to a new loudspeaker on a familiar track of 3 or so minutes then I will slowly form an opinion over the whole track. For example, at the first chorus I might think the vocal sounded a bit shrill when it got loud - when the second chorus is reached I can listen out for this again and try and confirm that suspicion. Perhaps I will decide this time that it was not a problem. Perhaps after the track is ended I will pick another track which I have more confidence that the vocal is cleanly recorded to double check. If I had done the same test with an A-B switcher I may have switched to loudspeaker B and repeated the part of the track - it is conceivable that loudspeaker B is a bit sucked out in the mid and gives a much less forward presentation, in this case I may come to a completely different conclusion about loudspeaker A. There is certainly a place for the A-B switcher but it is only to be used with caution! Jack. -- jackocleebrown jackocleebrown's Profile: http://forums.slimdevices.com/member.php?userid=10623 View this thread: http://forums.slimdevices.com/showthread.php?t=87592 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/mailman/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Squeezebox Touch with two USB DACs
JohnSwenson;630318 Wrote: > This theoretically COULD be done with USB DACs, but it could be a little > iffy. Running a USB DAC is FAR more "touchy" on the Touch, you can get > ticks and pops etc quite easily, using TWO of them is going to make > this WAY more likely to happen. > > The best bet would be very simple 16 bit only DACs, just 44.1, adaptive > (NO asynchronous 24 bit DACs need apply for this). DACs that use the > 2706 type USB chip would probably work. > > You would set the ALSA config using the existing method for having the > data stream sent to two different DACs, then use amixer to change the > volume between then. It might work. > > You would have to write an applet that got events from the IR system > and then ran amixer with the right options to change the volumes. > > Another major issue is going to be setting the names between the two > DACs. With two DACs you are going to have bizzare things happening as > to names and card numbers. Someone recently posted a UDEV scheme for > properly naming USB DACs, you would need to extend this for two DACs so > you could guarantee that ALSA was talking to the right things all the > time. > > So yes it might be possible, but its not going to be trivial. > > NOTE: I am NOT volunteering to do this! > > John S. Hi John, Thanks for the reply, what you describe is the kind of thing that I was thinking of... perhaps it is overkill for what I need and I think that something along the lines of Phil's suggestion is the way to go in this instance. I have just got hold of a USB DAC so I'll have a bit of fun playing around with that and the Touch, thanks for the info on your thread - very handy. Jack. -- jackocleebrown jackocleebrown's Profile: http://forums.slimdevices.com/member.php?userid=10623 View this thread: http://forums.slimdevices.com/showthread.php?t=87592 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/mailman/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Squeezebox Touch with two USB DACs
Phil Leigh;630225 Wrote: > The best way I have found of doing this is as follows: > > Touch to DAC with 2 parallel outputs to - 2 identical pre or integrated > amps that have configurable IR remote input selection (ie most > mid-to-high end "non hair shirt" gear). These are then programmed so > that selecting (say) Input 1 on one amp also simultaneously selects > Input 2 on the other and vice versa. > > A single remote push will now toggle between the same source via the 2 > amps+speakers. All very high quality. Thanks Phil, makes sense and is nice and simple... sounds like a winner to me. Do you ever run into problems that one pre-amp/integrated misses the IR signal? -- jackocleebrown jackocleebrown's Profile: http://forums.slimdevices.com/member.php?userid=10623 View this thread: http://forums.slimdevices.com/showthread.php?t=87592 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/mailman/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Squeezebox Touch with two USB DACs
ajmitchell;630213 Wrote: > Hi I think you are making this too complicated. You want to compared two > sets of speakers: set A and set B. First any SB outputs two sets of > digital (optical and coax) at the same time (see > http://forums.slimdevices.com/showthread.php?t=65692&highlight=outputs) > so you can run identical A+B side by side. > > However to switch from A to B and B to A (many times) you need either > an amplifier with a A B speaker set button (quite common) or a switch > on the digital out (at the DAC or to the DAC). Many DACs (even cheap > $100 ones) have digital input switching for optical and spdif (coax). > Ignor USB, as already mentioned there is no usb output). So you can > switch between the near identical optical and coax outputs. Lets say > you are obsessional and want to compare coax (spdif) with coax (spdif) > without bringing optical into the equation you can use a coaxial cable > splitter ( a high quality one is sold by QED (I think as subwoofer Y > cable) which works perfectly splitting one digital output into two > (with no quality loss). > > does that help? Thanks for your reply, splitting the spdif out to two different DACs was something that I had already been thinking about but the "switching" functionality becomes a little tricky. Especially as ideally this is to be done from the listening position so that the listener does not need to move their position when comparing two loudspeakers (similar issue with A/B switch on amps). I was under the impression that a USB DAC could be used with the Touch (perhaps after installing soundcheck's toolboz) -- jackocleebrown jackocleebrown's Profile: http://forums.slimdevices.com/member.php?userid=10623 View this thread: http://forums.slimdevices.com/showthread.php?t=87592 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/mailman/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Squeezebox Touch with two USB DACs
Hi Scottmonster, Thanks for the suggestion, I guess that if they are both playing we could then toggle the mute on each to switch between them does the mute sync between players? I was hoping for something a little bit cleaner though, easy for any of the engineers to use and remaining permanently setup. Cheers, Jack. snottmonster;630174 Wrote: > Just a thought - but wouldn't it be a lot less effort to just have 2 SB > Touch? You could sync them if you are wanting to switch between speaker > setups while your tracks are playing -- jackocleebrown jackocleebrown's Profile: http://forums.slimdevices.com/member.php?userid=10623 View this thread: http://forums.slimdevices.com/showthread.php?t=87592 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/mailman/listinfo/audiophiles
[SlimDevices: Audiophiles] Squeezebox Touch with two USB DACs
Hi all, I have a slightly strange requirement which I think might be fulfilled using the SB touch plus a little bit of fiddling with the software. A bit of background: I work for a loudspeaker company (KEF Audio) and we have been using the slimserver/squeezebox system in our listening rooms for a few years, we use the SPDIF out to feed an external DAC. As you might imagine, occasionally we want to compare pairs of loudspeakers and we have a switch-box which allows two sets of loudspeaker cables to be connected to an amplifier, there is a remote with a couple of buttons on it and the signal from the amplifier can be directed to either loudspeakers A or loudspeakers B with the press of a button. We are also able to trim the level of the loudspeakers in the switch-box system to compensate for sensitivity differences, this is done at line level between the pre and power amp. The switch-box uses relays to make and break the connections to each loudspeaker. The main problem with this situation is that firstly it is unreliable and secondly it sounds terrible compared to using a direct set of cables from amp to loudspeaker. We believe that this is just a problem of the relays which are not designed to be switched as frequently as in our application and they very quickly deteriorate - the system is reasonably good when the relays are fresh. I'd like to replace this ageing system with something better and I was wondering if it would be possible to use the SB Touch to do this by connecting two USB DACs to the Touch (via usb hub) and then to write a little plug-in to allow the output to be directed to one or the other DAC preferably triggered by a button press on the remote. We would then need to have two identical amplifiers to complete the system. Level matching could either be done in the switching plug-in or alternatively simply in the preamp of each of the pair of amplifiers. I have quite a bit of programming experience and linux experience too but I could do with some help getting started on this project. I understand that the Touch uses ALSA internally, has anyone tried to connect two USB DACs to the touch simultaneously? I know that soundcheck's touch toolbox allows some of the outputs of the Touch to be disabled - does this change the ALSA settings to disable the different outputs? Perhaps it is possible to simply use the ALSA mixer to do the switching/level adjustment. Any help is greatly appreciated. Best regards, Jack Oclee-Brown. P.S. I anticipate that there may be some responses regarding the "correctness" of A/B testing in this way so I'd just like to say that this is not the only way that we evaluate loudspeakers but also that we do find it a useful test for particular situations. -- jackocleebrown jackocleebrown's Profile: http://forums.slimdevices.com/member.php?userid=10623 View this thread: http://forums.slimdevices.com/showthread.php?t=87592 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/mailman/listinfo/audiophiles
