Yamaha 5740--Must I use optical cable?

Matt^Brown · 09-24-2005, 10:16 AM

Let's begin with apparently I know so much less then I think I know. :b About 8 months ago I started working on my HT and bought a 5740 and a Sony dvd player. At that time I purchased component cables for the video and analog cables for the audio. I then realized that I had digital optical cables on my new reciever and thought once I save up some money I am going to get one of those fancy cables.

Well a couple of months went by and I was just happy to have my surround sound all working and I forgot about the digital cable. Then one day I was at BB and saw a nice optical cable and thought I should buy it so I did. The cable is really nice and it looks great laying next to my HDTV but the problem is my Sony dvd player will only except a digital coaxial cable. I swore at myself a little but decide to keep the cable because this is the begining of a hobby and I am sure I will need this cable down the road for something else.

Another couple of months pass and I buy a digital coaxial cable because I know it will fit and that is when I realize that my Yamaha only excepts the coaxial in a spot marked CD. I hook the cable up to that spot and just like magic the sound comes out of my speakers. At first I am really happy because after two failed attempts and a decent chunk of change I have managed to hook up one cable. Then I realize that since my reciever is hooked up to the CD location that I seemed to have lost all the DVD options that I had before. I use to be able to choose the dynamic range I wanted and play with some other features it had but now it just says "STRAIGHT" across the front of the display.

Please tell me I have not been beaten. I hate to think this one cable has knocked me off my high horse of HT dominance. Amongst my friends I am a God. I have a dvd player, a satelite, a vcr, and a stero all hooked up to the same tv. I know for many of you all this may not seem like much but in my circle this is a big deal.

JeremyErwin · 09-24-2005, 11:20 AM

"Straight" is a sound processing mode that turns off all the options. Try selecting a different dsp mode (such as DD/DTS, or Movie).

The manual is here

You can also reassign the coaxial jack to the dvd input. This will probably save you some frustration down the road. Look on page 48 of that manual, under
"? Input/output assignment A)I/O ASSIGN"

In any case, you'll probably want to set your DVD player to output a dolby digital/dts bitstream rather than pcm. The manual should explain how to do this-- probably located in some audio submenu somewhere.

Matt^Brown · 09-24-2005, 11:33 AM

Thank you Jeremy for the input. I will try to tackle this beast again this afternoon. I am having a birthday party for my son so I must get everything lined up or I am going to look like a dumbass. I hate when people come over and say stuff like "can we hear your system you have been working on for 8 months?" only for me to reply. "No, I can't figure out how to hook it up."

The funny part is I really do love messing with this stuff and I wouldn't trade it for anything.

JeremyErwin · 09-24-2005, 11:44 AM

If you post the model number of your dvd player, I can probably give you more exact directions, provided that the manual is available somewhere online...

Matt^Brown · 09-24-2005, 12:05 PM

Thanks for the quick replys. I am currently at work so I can't check my Sony for the model number. If I get a chance before the party gets under way I will check it out and post it. I think based on your information that I will be able to figure it out. If not I will just unplug my CD player and lay it and some speaker wire on the floor in front of my tv. Then when people ask if they can get a Demo I can tell them I am moving stuff and it not currently hooked up.

It really works just fine the way it is I just hate not having all the DVD features available.

**HTF Ads**

Arthur S · 09-24-2005, 12:05 PM

Matt

Jeremy has some great ideas for you when you have time.

It is a little late for you as far as cables, but so that you can tell your friends, IMHO, it is not worth spending much money on cables. Especially "coaxial digital" cables. They are nothing more than RCA patch cords. 99.9% of the time you can use any old RCA cord, (of the right length, of course), and get perfect results. I would also recommend getting the cheapest optical cables you can find. Parts Express has a 6 foot optical for $3.25.

Joe*H · 09-24-2005, 03:32 PM

I did the same thing, just assign the coax input to dvd, very simple fix in the input section.

Gralen · 09-24-2005, 05:39 PM

I thought all Yamahas have both coax and optical cables inputs. Mines does and it is pretty old 1200. You could reassign the input. just go to the menu and go to I/O assign input and it can do that.I had to do that until I found out that I had the wrong cables

ChrisWiggles · 09-25-2005, 01:34 PM

Quote:

It is a little late for you as far as cables, but so that you can tell your friends, IMHO, it is not worth spending much money on cables. Especially "coaxial digital" cables. They are nothing more than RCA patch cords. 99.9% of the time you can use any old RCA cord, (of the right length, of course), and get perfect results. I would also recommend getting the cheapest optical cables you can find. Parts Express has a 6 foot optical for $3.25.

Careful! A lot of people spend too much money on cables that are just run-off the mill, however good cables matter.

For digital coax you should use a 75ohm cable, which can be any video cable or any cable labeled 75ohm, or any cable labeled digital coax. They are all the same, though build quality can differ.

Optical is a little bit more complicated but I never recommend optical just because there isn't really any difference except increased cost.

Arthur S · 09-26-2005, 07:18 AM

Chris

How many ohms is an ordinary 6 foot RCA patch cord? 5 Ohms?

For the sake of discussion, let's say RCA is 5 ohms vs. 75 ohms for a "video" cable. Exactly what does that difference of 70 ohms do to degrade the digital bit stream?

Thanks

ChrisWiggles · 09-26-2005, 04:54 PM

it does not "degrade" per se because it is a digital bitstream. However, there will be reflections occurring because of the wire impedance mismatch, and these reflections will be seen time-delayed at the receiving end and can cause drop-outs. Digital SPDIF transmission is fairly robust, but you can experience dropouts because of the wrong cable used. This is not to say that you *will* but it is far more likely. The fact that a basic totally sufficient 75ohm cable is maybe 20 bucks at any store, I don't see why one wouldn't be using a proper cable for this. When people are having problems with dropouts on an SPDIF stream it's almost always the cable is the wrong kind. However, who knows how many people are using the wrong cable out there and not experiencing any dropouts.

With analog if there is an impedance mismatch you won't lose the signal, but you will have signal degradations. With digital, the signal error correction is fairly robust so I don't know that there would be audible degradations, until you reach the point of reflective interference that causes the signal to drop completely in which case it's fairly obvious because you won't hear anything at all for a moment!