RCA or Optical Digital?

gmorris · August 2003

When hooking up a component, lets say a simple CD player, that has standard RCA type outputs & an optical digital output, which is the better choice? Lets assume you had cables of both types of equal quality. Lets also say you were connecting the CD player to a simple home theater receiver, not a fancy D/A convertor with a seperate Preamp/Amp. setup.

What would your reasons be to choose one over the other?

Later,
Greg:)

Frank Z · August 2003

Gmorris,
Welcome to the forum!
Do a search for "Coax vs. Optical" and you'll find a number of threads on this subject, some of them quite recent. It really boils down to what you hear and which you prefer. I swore that optical (Toslink) was the only way to go for years. Then I tried coax and was very surprised to find that on my setup the coax did infact sound better to me. Your results may vary!

Keep in mind that using 2 RCA connectors connected to the L/R outputs of your CD/DVD player will only allow you to listen to the stereo tracks. For multichannel music or DD/DTS you will have to use coax or Toslink.

burdette · August 2003

Originally posted by gmorris
When hooking up a component, lets say a simple CD player, that has standard RCA type outputs & an optical digital output, which is the better choice? Lets assume you had cables of both types of equal quality. Lets also say you were connecting the CD player to a simple home theater receiver, not a fancy D/A convertor with a seperate Preamp/Amp. setup.

What would your reasons be to choose one over the other?

Later,
Greg:)

So you're asking about choosing between a standard ANALOG RCA out, vs. a digital optical out, correct? You are NOT asking about a digital coax vs. a digital optical... is that right? I assume you're asking about the analog vs. optical because you specify a "simple CD player" and not a DVD player.

On that assumption, I'll take a stab at this.

First, if you use the analog out, you're running that analog signal through outputs, through a cable, through inputs... essentially a "long" signal path with several connections, and all that may or may not degrade the signal, and may or may not effect the quality (there are several juicy threads just in that statement). You'd be using the DACs in the CD player.

If you go digital optical out, then you're transferring a digital signal from component to receiver, and in theory should have no degradation of signal between the two. You'd be using the DACs in the receiver.

If the physical distance between the two components isn't that much, and if the DACs are of similar quality, and if the analog interconnects are decent, then I doubt you'd hear a difference. If the distance is pretty long, you MAY get enough signal degradation using the analog that you could hear a difference.

If the components are physically close, I'd go for the better DACs. If the DACs are equivalent, I'd use the optical because it is cooler, and, frankly, you WILL be getting a better signal to the receiver, whether you can actually hear a difference or not.

cmy330go · August 2003

In theory I agree with burdette. Assuming both cables are of high quaility you would want to use the better DAC's.

However I thought I would relay an experience I had.

Myself and a co-worker (polk club member "fireshoes") Did a test between optical and analog interconnects using a Yamaha RXV1, Denon DCM370 cd player, Lsi25's biwired with Z-Series Monster, and 400 series monster cable analog interconnects and similar grade monster cable optical. We both performed a BLIND test with each other by using the input selector on the receiver to instantly switch between the two connections, and on all tests we prefered the sound of the Analog connection.

So I would recommend that if you can, have a friend help you with a blind test and go with the connection that you prefer the sound of.

Just my thoughts.
Hope this helps.

burdette · August 2003

Originally posted by cmy330go
....go with the connection that you prefer the sound of.

I agree. I think I unconsciously add that sentiment to every post I write or read, even if only in my head. If it sounds better or best to 'you'.. do that.

Interesting on the shootout. Ever try it with different interconnects?

cmy330go · August 2003

Originally posted by burdette

Interesting on the shootout. Ever try it with different interconnects?

Unfortunatly I have only tried it with the monster cable. Sometime I would love to try some comparisons between brands. I agree that monster is better than the cheap stuff that comes with components, but as of late I am starting to realize that it may not be all it's cracked up to be.

cmy330go · August 2003

Originally posted by burdette

Interesting on the shootout. Ever try it with different interconnects?

Unfortunatly I have only tried it with the monster cable. Sometime I would love to try some comparisons between brands. I agree that monster is better than the cheap stuff that comes with components, but as of late I am starting to realize that it may not be all it's cracked up to be.

Imagine that.

AJ Audio · August 2003

I have a recording studio and I'm totally happy with rca connectors they deliver great quality plus optical is overpriced!

F1nut · August 2003

My understanding of using optical is that you are converting a analog signal to digital and then back to analog again. To me this makes no sense, keep it all analog, less conversion problems to worry about.

Loud & Clear · August 2003

Originally posted by F1nut
My understanding of using optical is that you are converting a analog signal to digital and then back to analog again. To me this makes no sense, keep it all analog, less conversion problems to worry about.

~~ So that would apply to digital coaxial, too, right?

~~ Also, do you run analogs from your DVD player to your reciever for DD or DTS playback? Seems like most people avoid that, except for DVD-A and SACD where you haven't an option.

~~ Hmmm, but now that I think of it, why is the opti cable making any conversion? Isn't it just passing the digital signal to the preamp stage of your amp, which then makes the conversion?

~~ Whatever, I'm pounding the wine.

gidrah · August 2003

Off the top of my head, I'd have to say go with the analog RCAs if it's less than a 3 meter run. Optical tends to add a bit of harshness, but the quality degrades at a slower rate over the length compared to analog. The quality of an entry level cable is also comparatively closer to that of a high-end cable (ie: save your money).

If it's a normal (1 meter or less) length, I'd probably go with the analog from your CD. With very few exceptions, I've found CD players just plain sound better than receivers.

Loud & Clear · August 2003

Originally posted by gidrah
Off the top of my head, I'd have to say go with the analog RCAs if it's less than a 3 meter run. Optical tends to add a bit of harshness, but the quality degrades at a slower rate over the length compared to analog. The quality of an entry level cable is also comparatively closer to that of a high-end cable (ie: save your money).

If it's a normal (1 meter or less) length, I'd probably go with the analog from your CD. With very few exceptions, I've found CD players just plain sound better than receivers.

~~ At the end of the day, isn't this really about DAC's? If your Cd/DVD/whatever player has a better way of processing the signal, then use a decent analog interconnect; if the situation is reversed, then pass the signal via digital coax/opti to the superior DAC in your processor, no?

~~ Now for something that's been bugging me: I have invested in, by all accounts, a fine CD player, as well as a decent integrated amp. So, I'm using a pretty good interconnect to translate the CD's signal to the integrated, which I assume bypasses the preamp stage (because that's where it WOULD be making a conversion) of my integrated. Well, what's the effin point in having an integrated with a decent preamp stage, if you're not going to be using it? Someone, please help me, seriously ... this bothers me. Are the fancy tubes that I have in my integrated's signal stage just collecting dust?

Frank Z · August 2003

Originally posted by F1nut
My understanding of using optical is that you are converting a analog signal to digital and then back to analog again. To me this makes no sense, keep it all analog, less conversion problems to worry about.

I could be off base here but, if we are talking about the analog outputs on a cd/dvd player the conversion would be from digital to analog via the DAC's in the player. The the optical or coax connection would carry the digital signal to the receiver/preamp for processing and use the DAC's in that unit. Yes? No?

RuSsMaN · August 2003

Ed Zachry, Frank.

Actually, you are converting from Digital to light, back to Digital, then finally to analog. (one reason I'm in the coax camp for sending a dig signal, less jumps)

Research, and use the better DAC, or just trust your ears!

Cheers,
Russ

Frank Z · August 2003

Hmmmm! I thought someone had changed the rules without letting me know!;)

F1nut · August 2003

Ah! Thanks for clearing that up.

burdette · August 2003

Originally posted by RuSsMaN
Actually, you are converting from Digital to light, back to Digital, then finally to analog. (one reason I'm in the coax camp for sending a dig signal, less jumps)

ACTUALLY.... isn't the conversion from digital information in the form of electrical signals, to digital information in the form of light pulses... and then back to electrical digital? The data is still in digital form, light is merely the means to carry that digital signal.

You choose between digital data transferred as electrical information carried over a coaxial cable, or digital data in the form of light pulses carried over an optical cable. The optical signal is not a distinct type of signal, simply an alternative means to transfer digital information.

Traditional amplifiers amplify an analog signal, so at some point the digital information has to be converted back to an analog signal, hence the focus here of the quality of the DACs. If you convert at the source, then you send an analog signal over the wire (analog RCA out). If you don't convert until the receiver, then you transfer a digital signal over the wire. A primary advantage of transmitting the digital information in the form of light pulses is that is has better immunity to interference.

The new "digital amplifiers" don't require the conversion of the digital signal to analog prior to amplification. Digital amplifiers amplify in the digital domain, doing away with the problems inherent to an analog amp (distortion, nonlinearity, etc). The amplified signal is then converted into an analog signal to drive the speaker. Hence thusly and soforth, their alleged benefit.

RuSsMaN · August 2003

Yeah, yeah. THAT's the ticket.

Show off.

Cheers,
Russ

GuitarheadCA · August 2003

K, someone explain this. CDs are written in binary code, ie, ones and zeros (on/off). To my understanding, this is one of the underlying principles that makes something "digital". It's not untill after the DAC that it becomes an analog wave function. This leaves me with two quesions:
1. how are ones and zeros different whether they travel in coax or fiber optic. (placebo effect here?)
2. how the heck can a digital amplifier work, ie, your analog sound wave is amplitude modulated, very easy to understand. How do you modulate the amplitude of something that doesn't have the shape of a wave?

I've always wondered about this- I hope someone sees where I'm coming from.

danger boy · August 2003

Originally posted by gmorris
When hooking up a component, lets say a simple CD player, that has standard RCA type outputs & an optical digital output, which is the better choice? Lets assume you had cables of both types of equal quality. Lets also say you were connecting the CD player to a simple home theater receiver, not a fancy D/A convertor with a seperate Preamp/Amp. setup.

What would your reasons be to choose one over the other?

Later,
Greg:)

Honestly, I can't hear a difference.. i've tried all three ways of hooking up a CD player. I did not notice any sound quality difference between the RCA analog, optical, or coax digital ones.

Where I did notice a difference in sound quality was when I use an external DAC. But your question was for not using a external DAC. SO i won't go there.

gidrah · August 2003

Originally posted by Loud & Clear
~~ At the end of the day, isn't this really about DAC's? If your Cd/DVD/whatever player has a better way of processing the signal, then use a decent analog interconnect; if the situation is reversed, then pass the signal via digital coax/opti to the superior DAC in your processor, no?

To a degree. I've found the DACs in CD players to be more musical to comparable DACs in receivers or preamps.

~~ Now for something that's been bugging me: I have invested in, by all accounts, a fine CD player, as well as a decent integrated amp. So, I'm using a pretty good interconnect to translate the CD's signal to the integrated, which I assume bypasses the preamp stage (because that's where it WOULD be making a conversion) of my integrated. Well, what's the effin point in having an integrated with a decent preamp stage, if you're not going to be using it? Someone, please help me, seriously ... this bothers me. Are the fancy tubes that I have in my integrated's signal stage just collecting dust?

I'm kinda confused here. I will assume you're sending a digital signal from CD to a tube integrated pre-amp. Either way you are not by-passing the pre-amp.

burdette · August 2003

GuitarheadCA said: "...translate the CD's signal to the integrated, which I assume bypasses the preamp stage (because that's where it WOULD be making a conversion) of my integrated. Well, what's the effin point in having an integrated with a decent preamp stage, if you're not going to be using it? Someone, please help me, seriously ... this bothers me. Are the fancy tubes that I have in my integrated's signal stage just collecting dust? "

To which I humbly reply...

You're confused on the function of the preamp. It is what it says.. it performs whatever function you want to perform before the signal gets passed along to the power amplifier. These functions include volume control (which is why the vast majority of separate amplifers don't have a volume control) switching between sources, tone controls, etc. The DAC is in line before the preamp - it is not part of the preamp - and the DAC feeds the pre the analog signal... and it becomes one of however many signal sources you have - CD, DVD, MOUSE, TV, turntable, tape, etc. That is why in terms of the preamp it doesn't matter whether you convert back to analog at the source or using the internal DACs. With the preamp, you choose whatever signal it is you want to deal with, make whatever modifications you want (like, volume), and the signal gets passed on to the amps to get boosted to a level that will drive a loudspeaker.

That is why some preamps have essentially NOTHING there except switching and volume, because everything else, like a tone control, can introduce distortion of some sort. Also why some preamps are passive (which is a bit contradictory).. i.e. no power electronics, because the belief that *any* device such as the electronics of even a good powered preamp will introduce its own brand of distortion, noise, etc.

burdette · August 2003

Originally posted by GuitarheadCA
It's not untill after the DAC that it becomes an analog wave function. This leaves me with two quesions:
1. how are ones and zeros different whether they travel in coax or fiber optic. (placebo effect here?)
2. how the heck can a digital amplifier work, ie, your analog sound wave is amplitude modulated, very easy to understand. How do you modulate the amplitude of something that doesn't have the shape of a wave?

I've always wondered about this- I hope someone sees where I'm coming from.

Well.. it started out as an analog wave function.. at least if it started out as a real instrument playing.

1. I don't know how else to interpret this question, so I think the answer is... in digital coax, the Ones are electricity ON and the Zeros are electricity Off. In optics, the 1 is light on, 0 is light off. You could actually have it however you wanted as long as the 'receiver' of the signal knows. But the point is, all that has to travel, all you have to be able to do, is differentiate between two things... not the infinitely many you'd have in trying to transmit an analog signal.

2. To increase the volume of a digital signal, you have to increase the Font size of the 1's and 0's, say from a Times New Roman 10pt to a TNR 14pt. Like this...
100110001011

100110001011

The second one would be way louder than the first. Ya, none of that is true. The deal is, a digital amplifier is a proprietary device that takes a digital signal input to control a power output. The only signals you're dealing with are digital and power, which are both less susceptible to distortion and interference than low-level analog signals. And you completely do away with the need for *any* DACs. Plus, the actual amplifer itself that can be used for a digital input is of a different design tha those used for analog input signals.. more efficient, lower heat generation. I believe digital amplifiers are Class D. Also.. I think.. not sure.. but I think a digital amplifier pretty much does away with concerns of load.. i.e.. no concern about driving a 4 ohm.. or even lower, speaker.

Loud & Clear · August 2003

Originally posted by gidrah
I'm kinda confused here. I will assume you're sending a digital signal from CD to a tube integrated pre-amp. Either way you are not by-passing the pre-amp.

~~ Gidrah, I'm using analog interconnects from the CD player to the integrated, so there's no digital signal, correct? The CD player makes the conversion and feeds it to the power stage of the integrated, right? Or does the pre-amp still work with the signal in this scenario? Thanks for taking the question by the way.

GuitarheadCA · August 2003

Burdette:
Um, Yeah, I simply didn't say the quote you quoted me for on your second to last post.

BUT, about your last post in regard to mine:
I don't think you understood my question. I know that coax transmits the signal via electrical pulses and fiber optic transmits via light. That's basics yo. My asking the difference was to imply
* How can someone HEAR a difference if they both carry the same binary signal.

and your example with the font illustrates the question I was asking - simply how DO you make a binary code LOUDER? Maybe what I'm getting at - is a "digital" amplifier really digital? This is without a doubt one of the most loosely thrown around terms in the a/v world. Manufaturers call all sorts of stuff digital that simlpy is not. Can you really amplify a digital bitstream?

gidrah · August 2003

I'm sorry. I understand now. Last night was the end of my personal happy hour. Tonight it's the beginning.

Read Burdette's reply. I started to reply (afterall, I was quoted), but realized he summed it up very nicely. Somewhere around hear Deanklipschead (sp?) got involved in a thread about passive preamps and posted a link to another forum that made for a great read. Try a search. I read it and understand it, but couldn't explain it for the life of me.

Either way. I'm sure that Jolida is a gem of an integrated and your CD player is sexy too. Rest assured that like most people around here, I'm jealous. If you have the digital ins and outs give it a try. If not, don't sweat it.

GuitarheadCA: Some can, some can't tell the difference. It may be placebo effect to a degree. It may also be the electrical to optical transfer on either (or both) end(s) that makes the point toward coax. Then again; long runs of coax or longer than necessary runs that are looped around, are more susceptible to RFI or EMI that can wreak havoc on jitter in a digital signal. This also depends on how close the cable is to such interference ( Is the cable close to the transformer that feeds the whole city block with A.C.?).

burdette · August 2003

Sorry if I misquoted someone or attributed something to the wrong person. No offense of any sort intended.. just a mistake.

Originally posted by GuitarheadCA
* How can someone HEAR a difference if they both carry the same binary signal.

Ya, well.. that is the question, isn't it? In theory, based on the fundamentals, I don't think they can hear a difference because there isn't a differerence. In practice, there *could* be differences due to ... oh... the electronics of the player.. maybe the conversion to optical isn't clean... or maybe they have a **** cable of one type or the other... or maybe the coax cable is picking up interference. So, there could be a difference due to *something*... but I don't believe it is fundamentally because, say, optical can't handle audio signals. Some people say optical "sounds" harsh, or whatever. I would attribute that to something besides the basic data transfer. But hey.. people claim they can hear differences between two brands of the same gauge speaker wire, and I don't believe that. Heck.. color the outside edge of your CDs green and get a better sound.. um.. OK. Whatever works for you... its all good as long as your kids have enough to eat and you're good to your woman.

and your example with the font illustrates the question I was asking - simply how DO you make a binary code LOUDER? Maybe what I'm getting at - is a "digital" amplifier really digital? Can you really amplify a digital bitstream? [/B]

To my understanding... the current 'true' digital amplifier uses the digital bit stream as the control for a analog amplifier. Whereas what we're all running is an analog power amplifier controlled by an analog input signal. It is within that relatively low-level analog signal where you get most of your trouble, assuming you're operating the power amp within a clean part of its spectrum. But the amplification is still an analog function. The "digital" reference in today's "digital audio amplifier" pertains to the control signal.. that it has not left the digital domain and has therefore not been subjected to potential distortion/noise/etc in the analog domain. I know that some of today's digital components like CD players or DVD players put out a digital signal of sufficient strength that you can directly feed an amplifier that uses a digital control signal.. doing away with the need for a preamp, but also doing away with your ability to switch between sources. Add a switch.. you've added a 'preamp.'

You can 'amplify' a digital stream in the sense that you can make the voltage for the 1 higher. But I think what you're talking about is.. say you record someone playing the piano and you record it directly in digital format. Then say you record that same person playing the same piano, but at a louder volume, and you record that directly to digital. Your question being.. can you take that lower volume digital stream and "amplify" it purely in the digital domain and essentially reproduce the digital stream that represents the louder recording?

Don't know. I've tried to keep up on digital amplifiers as it relates to audio. Current digital amps still have to ultimately put out an analog power signal because that is what you have to have to drive a loudspeaker. Now... I wouldn't at all be surprised if you can indeed amplify a digital bitstream within the digital domain.. but I've not read up on that, can't find anything on it, and it has been a little while since I was in school. Perhaps someone like HBombToo will read this and give us his 12 cents on it, or any other EEs out there.

RCA or Optical Digital?

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