Axiom Home Page Forums General Discussion Home Theater interconnects

Okay, I've decided to do it. I'm posting the question on interconnects... by now, we've all had our fun with the speaker cable question, but interconnects came up. I actually am quite interested in what makes a good interconnect. I know the contruction of the connector is a good reason to buy good interconnects, but other than that, any reason to buy good ones? How about fiber optics, what makes a good one?

For my interconnects, i have nothing expensive but enough to replace out of the box vcr cabling for sure. At most i wanted the usual copper or silver conducting wire (copper being cheaper) and have the wire housed in a sheath of some sort to cut down the EMF. I have found that with slightly better cables in my computer i have better reception with my cell and cordless phone in my office. The electrical interference generated is really alot more than one may think. But beyond that, i have yet to pay anything more than ten or fifteen bucks each for a/v cables, composite vid, toslink, etc. Most of what i have were ebay sales and most are Acoustic Research by brand (just by chance).

Nortel makes some pretty good fiber optic cable and i'm sure you can get it dirt cheap these days (both the cable and Nortel that is).
I find that the optical or digital coax connections provide a higher sensitivity from my cd player (vs hooking it up via RCA analog connections) but the sound is not really different.

Someone was telling me the other day though that if you use optical/coax digital from your cd player, you actually circumvent the DAC onboard your player and instead the DAC of the receiver is used. But if you use analog connections then the DAC on the player is the sound you hear instead.
If anyone has an idea what this person may be referring to, i'm all ears.

As far as the DACs are concerned, I'm certainly no expert, but what you say is true. The digital signal from the CD player is converted by the player's DAC (digital-analog-converter, I think) to an analog signal, then ported through the analog connectors to your receiver/processor. From there, the analog signal may be converted to digital and back again for bass management and other "digital sound processing" (DSP). There are those that think that all this converting and back again can result in signal distortion and a decrease in your sound quality.

More practically for me, I recently upgraded my old receiver to a processor with high quality DAC. My 13 year old CDplayer has had marginal sound, but I was using the analog output and a 13 year old DAC (the new DACs have much higher resolution). I had an instant "upgrade" 2 days ago to my CD player when I switched to a digital cable and utilized my new processor's DAC. Now, it sounds pretty darn good for an old mass market player! So it depends on the comparative quality of your 2 components, I think. If one DAC is better than the other, you're probably better off using that one. So you might get better sound using your analog outputs from your player, if your player is newer and higher quality than your receiver.

ChrisR

So lemme get this straight.
If i use analog connections, the cd player DAC converts digital to analog, carries it to the receiver, the receiver DAC turns that analog back into digital and plays the sound.
But, if i use digital connections, then the digital signal from the cd player goes DIRECTLY to the DAC onboard the receiver and hence NO processing occurs within the cd player.

Is that right?

So the question is then, as you sort of state, do you want to use the DAC onboard the cd player or on the receiver? Then answering that question will allow you to choose either analog or digital connection for cd to receiver.

As i was explained this earlier, the DAC on the cd should always be used preferentially over the receiver DAC since they are TYPICALLY of better quality due to their single use design (couple of assumptions here of course that both units are relatively the same age technology, quality/price range, etc.).
Hmm, i guess i should probably be comparing the DAC specs on my receiver and cd players then before committing to any new cd player/ dvd purchase.

Hi guys!

Well as best as I can tell, ChrisR has it correct in his assessment of the process of digital to analog conversion. And chesseroo, your first paragraph is also right. And you may be correct in that it could be time to compare DAC specs for receivers and DVD/CD players (if you can get that info). Whether (and when) a receiver converts a digital input signal to analog (for processing) is a design choice/option. Indeed, most units would keep the signal digital for any internal processing and only convert the digital signal to analog just prior to final amplification.

I have tried (and thus currently use) both a digital and an analog connection from my DVD player to my receiver. The analog connection is to the CD input. There IS a slight difference in sound between the two and the digital input is a bit "louder" (i.e. more sensitive OR the DVD digital output is higher) Anyway, the point here is that things in this arena are just getting more complicated all the time. Wanna hear a difference between a 192kHz/24bit DAC and a 96kHz/16bit one? WOW! gimmie more bits and khz anyday!

One other thing to consider - and this is not much of a factor anymore. Due to anti-copying considerations, some equipment (receivers) will not provide a digital output (to be available for copying) when using a digital input source (such as from a CD/DVD player) - for the very reasons of the purity of the unconverted (and unprocessed) digital signal being used. Its true that everytime a signal is converted back and forth, some type of distortion is added in. And thus the record companies are not too concerned about analog copying anymore.

Time to dump that old equipment with the inferior DACs!

Randyman

I'm using the optical connection between my DVD player and Onkyo 787 receiver, and I was shocked at how much better the optical connection sounded. It's much more dynamic and crisp sounding. I think it only became more obvious since adding the Axiom speakers.

When i was talking to a stereophile friend yesterday, his recommendation would be to use the optical connection for dvd to get that crisp, clear sound for the movie theatre experience but to use the analog for music.
However my dilemma was that i started off by looking for a dvd player to double as a cd player as well. Obviously i cannot use both the optical and analog connections unless the Onkyo receiver can actually switch between the two, and i don't think i paid enough money for such an option.

So instead, i'm now looking for a single dvd tray and will look around for a good used cd player 5 tray. Ebay here we come again!!

Ok then onto the next question.
Can someone explain to be the following:
"8 bit Burr Brown"

Hello Randyman, Ravi, Chesseroo, and ChrisR,

Getting back to Ravi's question on interconnects, a few comments: Of course, mechanical integrity is important, and, if you're running analog line-level signals more than a couple of metres (6 feet or so), so is the interconnect. Long shielded cables can have capacitance effects that will affect high-frequency response. If the latter is attenuated, you might perceive those changes subjectively as a "loss of imaging, or clarity, or a reduced soundstage", because all those are affected by reduced upper-frequency losses.

If you're using a turntable, the aforementioned capacitive effects become pronounced because the signal from a magnetic cartridge is only a few millivolts, and from a moving-coil cartridge, it's even tinier (microvolts). So don't use a cable between the turntable and preamp longer than 6 feet, unless it's ultra-low capacitance cable. (Capacitance is measured in picofarads--pF--per foot of cable and is sometimes stated in cable specs.)

Remember, however, with digital signals and coaxial or optical digital connectors, we're talking about PCM (pulse-code modulation)--just on and off pulses, the mathematical sequence of which "describes" the original analog signals from the microphones. On a CD or DVD, there is a huge amount of error correction (redundancy) always operating to fill in and replace any missing data. Frankly, I've used cheap and expensive coaxial digital interconnects and never heard a difference, nor should there be any if you understand how the above digital signals work. Nor is there any audible difference with optical digital connectors.

With analog video, we're talking major differences with long interconnects because video signals are MILLIONS of Hz (megahertz). Because video frequency response correlates directly with on-screen resolution, any loss of video response with long interconnects (15 feet or more) will show up on-screen as a loss of sharpness and clarity. I've only done tests with long shielded cables carrying composite video sigals; I presume the same factors would apply to S-video and component-video cables as well. So if you're running long video cables to a projector, it's worth getting really good-quality interconnects.

Regards,

Hello Alan

thanks for your response, it was very helpful, and was pretty much what I thought was true.

It leads me to another question, however. If attenuation is a big worry in interconnects, as well as interference, then wouldn't this also be true of speaker cable? If not, what is the difference between the two that makes it un-true.

I perceive a dig towards justifying expensive cable here.

If you look a bit closer at a couple of key points that Alan makes, you should be able to answer this question pretty easily (although Alan can correct me if i've mis-used his info).
He states that:
"Long shielded cables can have capacitance effects that will affect high-frequency response. If the latter is attenuated..."
This is the very reason why GAUGE of the speaker wire is more important than the 'technology' of the wire. The higher gauge speaker wire can carry a heavier load and reduce the attenuation of the signal over long runs (more explanation on this below).

"Frankly, I've used cheap and expensive coaxial digital interconnects and never heard a difference, nor should there be any if you understand how the above digital signals work. Nor is there any audible difference with optical digital connectors."
There is no disputing this really. It is kind of hard for a digital signal to degrade when the signal itself is essentially a bunch of zeroes and ones decoded back into an analog signal before the end link. Even if the zeroes and ones somehow lose some of their signal over the run, the end component still only has to distinguish zeroes and ones. A 'faded' zero or one won't change the way the sound is played but in an analog signal, a faded frequency is played accordingly.

Alan also states:
"With analog video, we're talking major differences with long interconnects because video signals are MILLIONS of Hz (megahertz)."
Keep in mind most music plays in the human hearing range of 20Hz to 22, 000Hz (or 22khz). Hence, speaker wire does not carry the same frequencies that a video signal does.
If we apply Planks Law of electromagnetic physics, the energy of an electromagnetic wave is in proportion to the frequency of the emission and inversely proportional to the wavelength. The energy of the signal is higher with increasing frequency and with decreasing wavelength (shorter wavelengths). And, short wavelengths attenuate faster than longer wavelengths. Therefore, one could conclude that the much higher frequency (and shorter wavelength) video analog signals are more likely to attenuate compared to a longer wavelength signal such as that which occurs through speaker wire. If you increase the distance over which that signal travels, you increase the chance its attenuation occurs to the point of, as Alan stated once again:
"...capacitance effects that will affect high-frequency response."

I have yet to see an entertainment setup in which someone has placed the dvd behind the couch with the tv in front of them requiring a 40 foot video cable run but if anyone wants to try, i would love to hear the results.

chesseroo

i'm not trying to justify expensive cabling, i was simply curious on the real difference between the two. your explanation made a lot of sense. i don't know much about electromagnetic broohaha, but your explanation was very understandable. I do wonder, however, if interference could cause attenuation in speaker cable.

Ravi, i'm just poking fun. I considered some more expensive speaker wire myself but more for the looks than anything. I still settled on some stuff slightly more than common zip cord but primarily b/c of the flexible jacket and the great price i got.

I would not be too concerned with EMF interference with your speaker cable. EMF interference is cut down a considerable amount by the outer jacket alone in the same way that a single pane window can cut down over 80% of the UV rays from the sun even though it feels warm on your arm.
I am guessing that the signal from the source to the speaker wire will be strong enough to display the same sound as a wire 'shielded' by some other metal wrapping. Distance between your wires is also another consideration. If anyone does not know much about electrical signals, i would tell them in the least NOT to wrap their wire bundles together and especially not with the power cords.

The only way to know for sure of any sound diff b/w highly shielded and not so shielded wires is once again to listen (or view as the case may be) for oneself.

Hello Ravi,

Thanks. Old hand Chesseroo made lots of good points taking off on my commentary, but one subject I didn't fully address was the matter of gain--the electrical strength (or weakness) of the analog signal through interconnects or speaker cables.

The "line-level" signals from a preamp or RCA connector are typically 1 volt or so, and a few thousandths of an ampere (very tiny) so the cables have to be shielded to screen out electro-magnetic and radio-frequency interference (RFI). If they weren't shielded and just one 3-foot length was placed anywhere near a 110-volt AC power cord, you'd get unlistenable quantities of hum!

But the signal through speaker cables has lots of amplifier gain applied (in the amp). Your amplifier makes the tiny 1-volt line-level signals thousands of times stronger, so when they emerge at the speaker outputs, they're from 20 to 50 volts and lots of amperes (sometimes) instead of milliamps (teeny-tiny).

So it's a matter of signal-to-noise, which means any interference is at such a low level that you'll never hear it because the audio signal from the amplifier to the speakers is so much stronger. (Digital signals through optical connectors are totally immune to all kinds of interference.)

Sometimes, in an eccentric installation, speaker cables can pick up RFI. When I worked at CBC Toronto in the late '60s, I lived only a block away from the old CBC TV transmitter on Jarvis St. I was getting the television sound when I listened to records on my audio system! Eventually I found the source: the speaker cables were serving as an antenna and conducting the signal back into the amplifier, where it was rectified (converted back to an audio signal) and amplfied along with the audio signal from my turntable! It only happened because I lived 100 yards from the TV transmitter.

The cure was to install shielded and grounded speaker cables between my speakers and amp. But that was a very unusual situation. Normally, you don't need shielded speaker cables, but if you have RFI problems, they are often required to eliminate the interference.

Regards,

Alan

I appreciate the response. I figured it was a bigger need for shielded interconnects because the signal was very weak, but your electrical engineering style explanation was fun! I always like to pick up more jargon!

chesseroo,

Backing up a bit to your previous comment about using optical for HT and analog for CD from your DVD player. I do just that from my Sony DVD player. I have the analog outputs going into my CD inputs in my receiver and the optical/digital imputs into my DVD input on my receiver. That way I can switch back and forth between the CD and DVD even when just playing music. THis is how I discovered the lack of "output" to the tape recording output jacks when using the optical input from the DVD player. i.e. if I want to record a cassette tape from from a CD, I have to use the analog (CD) input to my receiver. If I switch over to the optical (DVD) input on my receiver, there is no signal going to the tape outputs so I cannot record to the cassette!

No big deal (considering the fidelity of cassette) but just a curosity. I think you should try a similar hook up (providing you have standard analog audio outputs on your DVD player - and you should!
If you don't have separate DVD and CD inputs on your Onkyo - try the "aux" input!

Give it a look and see if you can.

Randyman

That's a great suggestion.
I never thought about the switching inputs deal. I believe that is 'doable'.

thanks, now if only i had my new dvd...

Chesseroo,

If I can throw in a comment, I had a similar experience with my DVD player when I was rapidly gaining an understanding of all the techie jargon i.e. how to use it as both a music and movie player.

In the setup menu for your DVD player, there is probably someplace where you can choose how signals will be sent to the receiver, either digital "Stream/Bitstream" or analog "PCM", or both. If you select both, whatever software is read (either DVD or CD), the player will send both analog and digital signals to the receiver. Plug your analog interconnects into the "CD" input on the receiver, and the TOSlink/coax cable into the "DVD" input, to do the 2 input trick.

When you play back music with the receiver in "CD" mode, a digital signal will simultaneously be sent, but will simply be ignored by the receiver. Likewise, in "DVD" mode, the receiver will also be fed a 2-channel analog signal, but it will be redundant.

As a word of caution, DVD players are notoriously awful with 2-channel music if the rest of your system is good enough to reveal it (which in your case with an Onkyo and Axioms, it probably is). In fact, I A/B tested my 15 year-old Technics CD player vs. a Denon DVD changer, and the Technics performed better with 2-channel.

It all boils down to what a piece of hardware has to do. A receiver has the difficult tasks of decoding surround soundtracks and powering speakers. Asking it to do anything other than that, in particular handling music, is a crapshoot. Likewise, A DVD player has to handle complex video processing. Considering the average DVD player is the same size as a CD player, how much circuitry in the player is actually devoted to music processing?

What were you saying about hitting eBay again?

Hi fhw,
I had absolutely the opposite experience when I compared my old dedicated cd player versus the fairly new Toshiba 2800 DVD player. Within just a few notes I began to realize just how much music I have been missing. It was very similar to the first time I heard my old music through new Axioms.
Good Listening.

Hey fhw,
All that digital signal processing/decoding etc. is done inside tiny little integrated circuits (ICs) They don't take up much room inside the receiver or the DVD player (as long as they are not constructed with that super high grade exotic speaker cable!!!) Heh heh!

When it comes to decoding audio or video (inside a DVD player), I think most newer units do both pretty well. I am surprised that your older technics player sounded better than your new DVD player. I only bring this up because of the newer Super Audio CD and DVD-Audio formats. Both require higher end (better/more sophisticated) decoding/processing units and most of the units that play these high end formats are ALSO DVD players.

I am "waiting" to upgrade my DVD player so (hopefully) I can find a 5 disc changer unit (with DTS decoding?) and progressive scan output that plays DVD-A and SACD! Nobody does that yet - but I am hopeful some good company will soon.

All the best!

Randyman

SurinderDhoti,
Do you use the analog connection for your CD listening, or use the digital connection for both DVD and CD?
lando

At this rate of having my foot shoved back in my mouth, I'm likely to develop a complex.

In any event, I've always understood that there are so-called "clock errors" when a DVD player reads CDs (excluding higher-end DVD players), which leads to significant problems playing back 2-channel.

SurinderDhoti, do you use analog or digital connections for CD music from your DVD player? If you stick with digital, may I ask what receiver you're using (that does a better job with music)?

Randyman

the brand new Denon's do that

check it out

www.denon.com

DVD9000 (i think, not sure) is the model.. 64 meg buffer, too

That's a very good point fhw, and a local friend of mine, the stereophile, was explaining it in the same way (about the processing onboard various components).
I have yet to actually buy a dvd player and originally my thinking was to get a dual dvd/cd usage out of it so i was looking for good priced 5 disk tray dvds (specifically i had it narrowed down to the new Panasonic CV52).
However, given the fact that i didn't like the sound of my friend's Panasonic (RC32?) dvd player for music (compared against my old technics and an all-in-one denon we have in our kitchen), i started re-thinking my purchase decision.
So now i'm left with trying to find a quality single tray dvd and a cd player that will have that sound i'm looking for. I think finding the cd player will be a more prolonged search but i'm leaning towards new technology with the latest encoding chips.

Any suggestions on good names for cd players and dvds? (I was told offhand that Panasonic, Toshiba, Hitachi and Sony are relatively reliable for quality and service).

Randyman, now the question is, which cd format will be supported in the future?
SACD or DVD-A? (beta vcr or vhs vcr? sound familiar?)

We should think about moving this to another thread, but...

Cambridge Audio, NAD, and Rotel make high-value CD players that are not that much more expensive than the mass-market stuff (around $600 Canadian). If you have the extra bucks to invest, I've been auditioning a bunch of very impressive "entry-level" products from Arcam, Rega, and Myryad. Just amazing clarity and soundstaging, but they get up into the $1000-1500 Canadian range (about $700-1000 USD).

You might think about taking your receiver into an audio shop and A/B auditioning the CD players, or leaving a deposit/credit card # and taking two players home to test with your system. Good dealers will usually let you do this.

chesseroo,

If I could predict THAT - then I'd be the next Bill Gates!!!

Audio/video history is full of this sort of thing:
Fortunately we in North America only had 2 major formats competing for video. Europe had 3!

In audio we went thru quadraphonic sound with QS and SQ matrix plus CD-4 discrete records. We had 4 and then 8 track, open reel tape (2 serious sizes), cassettes, elcasettes, two different digital cassette formats... (I could go on, but you get the idea)

After having been (ultimately) burned on the Beta vs VHS thing, I can say without a doubt, that quality is NOT the ultimate issue for competing formats. Marketing, licensing, and profits are the deciding factors (for the manufacturer). Convenience, price, and compatability seem to matter most for the (mass market) consumer.

I read a head to head test several months ago of the two new high end audio formats (I think it was Audio Review magazine - but not sure) Seems there is no clear winner (at least right now) but it looks like more companies are supporting DVD-A with their products. Once again it seems it's Sony (SCAD) against (almost) everybody else. What bothers me most is incompatibility. SACDs won't work on normal CD players.

But ultimately I see it all as a chance to sell more (new and more expensive) hardware AND incorporate very sophisticated anti-copying schemes into the hardware/software. The record companies really HATE those mp3 files ripped from "their" CDs! And companies like Sony and JVC (i.e. in the family of Matsushita/Panasonic/Techniques) are big into both the music business AND hardware manufacturing.

Sigh...... we little people will NEVER win!

Randyman

And if only the formats would stop there...but they don't.
THere is the big dvd-rw vs. dvd +rw
and of course we can't forget our all favorite HT encodings:
DTS
DTS 6.1
Neo
Dolby digital 5.1
etc etc etc

Just one suggestion, Chesseroo; don't deny yourself the convenience of a multi-disc cd/dvd player thinking that somehow a single-disc player would have better sound. This is yet another of the audio mythologies which are floating around.

I don't think it was a 5disk vs. single tray that was the issue but more that a dvd player may not be as well 'tuned' towards audio playback than a dedicated cd player.
We discussed a bit the other day about starting to compare DACs onboard the dvds, cdplayers and receivers to see if by specs any were truly lopsided in their potential performance.

I will probably give the Panasonic another try but with the analog connections to test out the DAC onboard that unit since last time it was really the Onkyo receiver DAC i was listening to.

I think a whole new thread on this topic should start up. I would be interested in knowing what others are using for dvd or cd player combos.

make it so!