Film-Tech Forum ARCHIVE: Toslink.

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Posted by Stephen Furley (Member # 1277) on 11-10-2008, 05:56 PM:

Does anybody have any experience with sending Toslink over extended distances? I'm looking at something like 35 metres, and I suspect that given the large diameter plastic fibre, and short wavelength used, it's not going to get even that far. Are there Toslink-AES converters available which don't cost a fortune?

Posted by Mark Strube (Member # 4190) on 11-10-2008, 06:41 PM:

Might digital coax be an option here? What's the intended application?

The distance you're going for is well outside of spec for toslink cables without some sort of amplifier.

Posted by Tristan Lane (Member # 1169) on 11-10-2008, 07:45 PM:

Toslink to SPDIF converters can be had for pretty cheap. Radioshack sells them.

Posted by Stephen Furley (Member # 1277) on 11-11-2008, 03:55 AM:

Tristan,

I don't think S/PDIF would do it either; it's only rated at 10 metres, and I think my estimate of 35 metres may be a bit under. I probably need to allow for 40 metres to be on the safe side.

Mark,

It's for a show next year in a theatre/concert/multi-purpose type venue. There is need to get audio from a laptop on a lectern on stage into the sound system. The laptop offers two outputs, unbalanced analogue which is quite noisy, and Toslink. I haven't seen the venue yet, but I'm told that they can take AES in both balanced and ubalanced form. There are XLR cables from stage dips up to the sound box, and also 75 Ohm co-ax which was put in many years ago for composite video, but has never been used.

The performer on stage needs to be able to play clips of pre-recorded audio in response to the audience, and speed is important, cueing somebody on the desk to play the clips would cause a delay.

The other way that I thought of doing it was to play the clips from a computer in the sound box, and make a remote desktop connection to this to control it from the laptop in the stage, but there is no network cabling installed. Taking a long length of Cat-5 around the walls would be a possible, as would using a wireless network, but I'd rather avoid that one if possible.

It looks like the best options would be to convert from Toslink to one form or the other of AES and send that up over the existing cabling, or run an Ethernet cable up and remote control the machine playing the clips.

[ 11-11-2008, 06:54 AM: Message edited by: Stephen Furley ]

Posted by Phil Ranucci (Member # 3820) on 11-11-2008, 03:43 PM:

Go from the audio output of the laptop into 2 DI boxes for left/right. That will convert the analog output into line level audio, plug them into the lines going to the mixer and you're done.

Posted by Bruce Hansen (Member # 281) on 11-11-2008, 07:19 PM:

Consumer plastic fiber is CRAP. Don't try to go more than 50 feet. You should be able to go at least 1000 feet with SPDIF over 75 ohm coax. Don't try to use cheep RCA audio cables to carry SPDIF though. To use AES you must have 110 ohm balanced audio cable. Regular balanced audio cable will not carry AES very far.

Remember SD-SDI (video) runs at 270 Megs, and will go 1000 feet down 1505A or 8281. SPDIF has a MUCH lower data rate.

Posted by Steve Guttag (Member # 268) on 11-11-2008, 11:17 PM:

AES3-id I'd give a better chance at 1000'. S/PDIF runs at half the voltage and the other end is less likely to be able to deal with way undervoltage signals as S/PDIF devices normally are presummed to be within 6-feet or so.

RDL makes a nifty device that isn't too pricy that will convert between optical and coax (RCA or BNC) and can be used to extend an otherwise weak system. It does not reclock the signal but auto levels it. It is called the FP-SPR1

For your application, a better product would likely be HR-UDC1. Unlike the other unit, this one reclocks the data and is supposed to actually output the AES3-id at the proper level (1V). This will go a long way with typical RG59 and RG6 cables. Odds are the receiving equipment will deal with the resulting signal just fine. Unfortunately, it is going to be a bit more pricy.

Steve

Posted by Stephen Furley (Member # 1277) on 11-12-2008, 07:01 AM:

Phil's suggestion might be an option, but I find the analogue outputs on most laptops are noisy; I think a lot of it comes from the display circuitry, that's why I wanted to use the Toslink output, it tends to be cleaner. I suppose taking the Toslink and converting it to analogue on a decent balanced line might be an option.

Steve, that HR-UDC1 box you pointed to looks interesting, I can think of several places where I could have used one of those in the last couple of years or so. Digital audio's getting a lot more common now, it was all analogue when I worked in A/V, but that was quite some years ago now.

It's a pity that it doesn't provide analogue inputs and outputs as well, then it could interface just about anything, but a HR-DAC1 would do that, and the two would mount quite nicely side by side. It's also a pity that it won't take 240V, that means yet another mains adapter to cart around.

The other problem is that I can't find any British distributor for it, or indeed any mention of it on a British site search in Google. It is CE marked, so it should be possible for it to be sold in the EU. There's a 'phone number in Holland, but I don't speak Dutch. I might try calling the American number and ask if they have a distributor here.

On an American site the HR-UDC1 was about $600, not the cheapest converter around, but not impossibly expensive, and not too bad for the spec. The cheaper converters that I've looked at don't handle all four interfaces, so it would take two or more converters to do the same job.

Something else that I'd find useful is a device to bridge digital audio over Ethernet. We have peenty of bandwidth available, including Gigabit to remote sites, and various forms of QoS on our switches. We don't have any problems sending CCTV, or hundreds of voice calls over Ethernet, so it should be possible.

Posted by Sean Kapp (Member # 4839) on 11-12-2008, 01:23 PM:

Stephen,

I have been in the presentation business for over 2 years now with they company I work full time for providing Audience Response technology here in the US. Most of the time the presentations we are involved in have some sort of audio involved with them from the presenting computer be it in PowerPoint or some sort of video format.

Phil's suggestion of running into a DI box should work fine for what you need. The DI boxes greatly clear up any noisy audio issues.

Some DI systems that I have successfully used here in the states are as follows:

D'san's Laptop Sound Port
http://www.dsan.com/Audio/Audio.asp

Behringer ULTRA-DI DI400P Passive Direct Box
http://www.guitarcenter.com/Behringer-ULTRA-DI-DI400P-Passive-Direct-Box-182498-i1125230.gc

Radial ProD2 Passive Stereo Direct Box
http://www.guitarcenter.com/Radial-ProD2-Passive-Stereo-Direct-Box-103147138-i1124779.gc

Some of these will need various audio adapters to convert the 1/8 laptop to 1/4 DI but they all work well for what you need.

Best of luck with your project!

Posted by Steve Guttag (Member # 268) on 11-13-2008, 08:48 AM:

Stephen,

On the HR-UDC1...the LIST price is $593.04US. I can assure you that you can have it for substantially less...from me if need be (and it was not my goal to be your dealer in this...just provide information...I'm surprised that there isn't a dealer for RDL in the UK).

Note, the FP-SPR1 LISTS for $181.15US...and again, can be had for substantially less.

For power...RDL stuff runs on 24VDC...anyone's 24VDC. However, RDL does accommodate European countries with two different supplies. The PS-24U2 is a universal supply that can take 50/60Hz and 100-240VAC. It is CE approved with an IEC AC input and a suitable power jack for the output.

Additionally, they make a European specific "wall wart" type supply, the PS-24E. It is rated at 230VAC in and uses at least one of the Euro type plugs (I've never sold one so I don't have more info on it). It too is CE rated.

Whereas RDL has an European office (31) 20-6238-983...I would presume that calling them could get you going in the UK. To have a single European office would seem to imply they have the ability to handle multiple languages. Whereas RDL is an American company, I would have to presume that they have someone there that can speak English just to deal with the American side of things.

If all else fails, email me and we'll work something out.

Steve

Posted by Stephen Furley (Member # 1277) on 11-13-2008, 03:03 PM:

Steve,

Thanks for the info. The telephone number you give is the one in Holland, which is listed on RDLs website. When I scrolled further down the home page there was a link to international distributors which I hadn't noticed before. There are two British ones listed. The first of these has a website which lists various makes of equipment which they sell, but there's no mention at all of RDL, and no answer on their 'phone number. The other is right at the opposite end of the country. They also have a website, which does list some RDL equipment, though much of it seems to be different to that listed on RDLs own site. The 'Half-Rack' range, including the HR-UDC1 and the HR-DAC1 is completely missing. There are two somewhat similar devices in a 'Rack-Up' range, but it's not just a question of different enclosures, the specs are also different, and not as good as the 'HR' devices. I might give RDL themselves a call, and see what they say.

The list price you quote is the highest I've seen from various distributors in the US; the lowest I've seen is something like 30% lower.

I try to avoid 'Wall wart' type adapters, in favour of ones which tale a standard IEC mains lead. There are two reasons for this, firstly the wall wart type are generally too big to be able to fit more than two in a standard British 4-way mains block, so it's generally better to use something with a standard mains plug on the end. Secondly, it's easy to just swap the mains lead if it needs to be used in a different country.

Posted by Steve Guttag (Member # 268) on 11-13-2008, 05:54 PM:

Stephen,

"List" price in the US is what the manufacturer "lists" it for. It does not vary from distributor or dealer to dealer. Then there are the prices that things are sold for. Sure, some will try to sell at list...which seems to be merely a basis to derive other prices.

In your post, you listed the HR-UDC1 as $600. I noted the actual list price was $593.04...that is what RDL lists it at. RDL also has what they call a "Pro-Net" which I guess is a suggested selling price. Many companies use "MAP" pricing though and put restrictions on how one may advertise their pricing. As I said before, though, the usual "street" prices will be considerably less than "LIST" which should always be the highest. If a manufacturer will sell direct, then they are supposed to sell at "LIST."

As to your UK distributors...I see one is a bit more versed in RDL than the other. It looks like they are still listing the older product, the RU-UDC1 which was part of their Rack-Up line. Many of the RUs have been phased over to the new Hafl-Rack "HR" series. Odds are, they either have RU-UDC1s in stock or they will tell you that it has been updated to the HR-UDC1.

Steve

Posted by Bruce Hansen (Member # 281) on 11-14-2008, 10:50 AM:

I just ran 1000' of good old RG-59 (8241) from the SPDIF out on a CD player in one room to the SPDIF input on a DAT recorder in another room. It works just fine. I then added another 75' of RG-59 (the see if you are about to fall off the cliff test), and it still worked just fine.

Here is a tech note from Belden about digital audio: Belden TB65
There is a chart on page 11 that talks about how far signals will go over different types of cable (SPDIF is not listed). BTW, 1505A is the newer "digital" version of RG-59, and 44.1KHz/ 16 bit over SPDIF runs at about 5MHz.

Posted by Robert Minichino (Member # 3495) on 11-14-2008, 12:17 PM:

I have abused SPDIF in all sorts of horrible ways and have never had it fail. I've transmitted it between buildings over existing CCTV coax (about 2500' of RG6, I think), and even a wireless video transmitter.

Posted by Bruce Hansen (Member # 281) on 11-17-2008, 10:59 AM:

If you are looking for a Toslink to SPDIF converter, Markertek has the TV1-POF830 for $24.65. The distance you are talking about sould be no trouble for SPDIF.