Cross-talk and distortion, chief soundstage contributors...

After reading ~ 10 ,posts with no mention of deferentially balanced amp and preamp I tapped out

We already started digital remember? There is no conversion. If you start with a digital source no analog crossover (signal level) will ever touch a digital crossover.

That makes no sense to me.

No it wouldn’t until you’ve tried it, too much converting back and forward, just like slotting in a digital active xover like a Deqx or mini DSP instead of using a very good analog active xover like the Pass B4.
Same deal all round, one becomes very sterile and digitizes’s sound, the other doesn’t and keeps the harmonic structure in tact. And the sound of your prized dac.

That makes no sense to me. Most high end DACs have very good reclocking if not buffer and reclocking such that external jitter sources make almost no difference and even if it did, an <$10 clock source with a tolerable power supply is essentially jitter free. Way less issue than anything you would do in the analog domain.  It's no different from things such as external oversamplers, etc 

Trouble with that is there goes the sound of the owners prized dac, because now there’s inferior cheap digital stages in use in the signal path. Been down that dead end path, trying to do digital domain xovers, you ruin any class your prize dac had.    

georgehifi6,991 posts

Thanks I understood how you explained it.

What about two preamps like a pair of C4s and two monoblock amps.
How is the phantom center created? Only from the source?

I could never get great stereo sound out of mono preamps paired with mono power amps. I never tried it the other way around, two mono preamps on a stereo power amp, though.

Regards

Is this measured? Are we measuring this? What is the measurement?

You can simply do it yourself without any measuring gear, put a 10kohm pot between L and R channels on the output of your source, and get some one to slowly reduced it till it shorts L and R together, while your listening.
That’s basically what I did in the demo above but with a fixed resistance to reduce the cdp to 30db channel separation.

Now if you devise a circuit in a box for the cd output to mimic the separation curve of the Lyra cartridge https://ibb.co/3Y9jM2W , then your early ping pong cd’s will sound better like vinyl can do to them. I’ve already named it, and called it "The Digital Vinylizer"

Cheers George

Now, this seems significant:

"The more you bleed left and right towards mono, the better the central image becomes, and the worse the image either side of center l & r and out side the speakers image becomes. "


Is this measured? Are we measuring this? What is the measurement? Is it articulated as a norm, in amp descriptions? 

I am not of the opinion that the room accounts for the majority of the sound stage. It may be one component but that is only part of the equation.

Right. Soundstaging is almost entirely having the speakers precisely symmetrical and in phase. Everything else makes a difference. But none of it matters if the speakers are cockeyed and out of phase. Anyone doesn't get that flunks Audio 101. 

listening99 OP
The "bleeding" of information from one channel to the other, is what I'm seeking to understand - how does this impact sound-stage?

The more you bleed left and right towards mono, the better the central image becomes, and the worse the image either side of center l & r and out side the speakers image becomes.
Vinyl is classic at giving a great central image at barely 30db of channel separation at 1khz in the midrange, but it's bass is almost mono, and it's treble isn't that much better.
Here is a expensive Lyra phono cartridge channel separation graph.
https://ibb.co/3Y9jM2W

I did an experiment for an audience on the output of a cd player to bleed the both channels down to 30db max, with a switchable circuit, and everyone preferred it playing old Beatles etc etc. Because it gave more richness to the mix, even though it was almost mono'ized and only had a central image. 

Cheers George

       

With respect to amp, there are some merits in term of reducing cross-talk improving soundstage. Everything else being equal, I found that dual monoblock amps tend to have a more stable soundstage and focus. Intuitively, the less interference between the leff-right channel will improve the soundstage focus.

And of course having a well treated room will improve the soundstage as well. Likewise, better DAC, better cables, and so on will help as well.

As for cross-talk, there is more than just left-right channel.  There are cross-talks between the woofer and tweeter as well.  That's why bi-amp will eliminate the woofer-tweeter cross-talk which will in turn improving the soundstage and image focus.

The "bleeding" of information from one channel to the other, is what I'm seeking to understand - how does this impact soundstage? I brought this up because I'm researching amplifiers, ad nauseam. Perhaps I should start a thread for dealing with the ad nauseam approach to buying new, expensive, sound-tech-trophies, or something. 

So, this subject, particularly the crosstalk element, arose in discussion with an amplifier manufacturer, who wrote the following: 

"Crosstalk is a measure of how much undesirable left signal is mixed with right output. Amplifiers all being one box are doing their best to be separate boxes one per channel, splitting apart the signals to ensure when it reaches the speakers, you can tell that the singer is standing slightly to the left of the stage and the violins towards the right. The more crosstalk there is, the harder it is to pick out the positions of the instruments as stereo separation is affected."

What do you make of this perspective???

@bigkidz can you speak to crosstalk within the amplifier's purview and how amplifier crosstalk alone influences soundstage? 

erik_squires8,583 posts04-19-2020 2:21pm

Answer my own questions then. Words matter!!!

If this was directed towards me, I am not obligated to reply to anyone. I often chose to reply to people who are nice and use complete sentences and make cogent arguments which leave open the possibility of a misunderstanding.

Best,
E

heaudio123367 posts04-19-2020 2:37pmI will take that as directed towards me ....
Channel separation is a measure of cross-talk between two complementary channels. Yes words matter. Understanding what those words mean is important too :-)
One source bleeding into another is also cross-talk. Tends not to be an issue in any competently designed product.

No guys I'm dence. It takes me a while to catch on, and figure it out.

But channel separation and crosstalk are two different things, when it comes to balance in a stereo. Crosstalk is the point where two channels cross and the communication between the two exist.

Channel separation is the point where there is not any communication between the two.  Two entirely different thing. 

I use to measure crosstalk, on a job site so I could get the best channel separation. Between wireless remotes. 

That why I didn't understand.

No finger pointing, thumbs pointed back. No ones obligated to answer, I'm just obligated to TRY to understand. Personal thing...

Regards

I am not of the opinion that the room accounts for the majority of the sound stage.  It may be one component but that is only part of the equation.  In building components, when I first brought my DHT DAC over to Audio Connection a number of years ago, John Rutan's reaction to me was wow this is like 4D.  He told me to name the DAC the Fun Box.  Same system he was listening to but the DAC changed the sound stage dramatically.  You can change the sound stage with different resistors - I know I keep saying the same thing over and over again.  Add an AC filter choke and you will have an impact on the sound stage for cheap also.

Happy Listening.

Answer my own questions then. Words matter!!!

If this was directed towards me, I am not obligated to reply to anyone.  I often chose to reply to people who are nice and use complete sentences and make cogent arguments which leave open the possibility of a misunderstanding.

Best,
E

A more relevant amplifier characteristic is the ability to fully and believably render the complex harmonic structure of different instruments. When these are not done well then the instrument never does sound truly believable and so it is impossible for the ear/brain to ever tell you its really there. Yes the famous Fremer line, there's more there there. 

This is another one we don't have a specification or measurement for but people can hear it, they know when its there and when its better and when its worse, and the amps that do the best at this also do the best at throwing a believable sound stage.

Interchannel crosstalk:  the TOTAL amount  two channels are crossed.

vs

Channel separation: where they are NOT crossed at all.

vs

Crosstalk: one source bleeding into another source normally through a 
preamp.

Answer my own questions then. Words matter!!!

OP wants to know about interchannel crosstalk, not channel separation
again differential vs non differential amps, talking about amps, and sound stage, right..

Fully differential preamp and amp will give the best results.  That is the quest OPs on, right, wrong? Eliminate distortion via complete channel separation.

What does a cart have to do with that, all carts have channel separation issues. Still the best when it's right.

Regards

And, don't forget about harmonic distortion.-Especially odd and even ordered harmonics, which the human ear can distinguish and play a role in how the sound of the amplifier is perceived.
Bob

If we ignore the "chemistry" of sound, and focus on 1 component alone, then yes kind of sort of.

Truthfully you don't need perfect crosstalk. Look at how poor LPs are compared to CD's and they can image wonderfully.  I think about -60 dB in the midrange is a great number. 

Same for distortion, lots of tube amps have relatively high distortion and image great. :)

So, yes, you can built a crappy amp with high cross talk and so much distortion you can't listen to it, but that only goes so far.

But in today's market, with many good amps measuring well in both dimensions, the room and speaker integration are FAR more important areas of focus to me.

Best,
E

Erik is 100% right .. it's the room.

Um, hello??

I'm focusing on the amplifier, alone... Again, the issue here are the fundamental (amplifier) qualities involved in soundstage. 

OP specifically indicated amplifier qualities involved in soundstage. Amplifier. Not room. Not speakers. Amplifier.

Erik is 100% right only if the question is focusing on the room alone. Then he would be right. Room. Amp. Two different things. If you can't tell the difference maybe read more, post less?

So anyway, amplifiers. Sound stage. We've eliminated crosstalk as a factor. What's left?

Well, not much, at least not if you're talking things that can be measured. Distortion doesn't matter. Plenty of amps with high distortion that image better than amps with measurably lower distortion. So we can throw that one out. S/N, dynamic range, hard to think of anything we can measure that would work as a reliable indicator of an amps ability to throw a palpably wide and deep stage.

That's the problem, listening99, audio always leaps in one fell swoop into areas where it becomes painfully obvious measurements are weak at best. More likely to lead you astray than where you want to be.

Amplifiers that throw a stage that is wide and deep and layered are wonderful. If that's what you want then I suggest you seek out amplifiers listeners have described as throwing a wide, deep, and layered stage.

Yes it really is that simple.

There is no substitute for Signal to (Noise + Distortion) Ratio. But analyzing the various contributions to Noise and Distortion is not straightforward, the total Noise and total Distortion represent the sum of the various contributors. No one source of Noise or Distortion holds sway over the other sources. How many sources of Noise and Distortion are there? And what are their percentage of contribution? Hey, that could be a pop quiz!

What am I missing here. Crosstalk? What does crosstalk have to do with soundstage?. 

One or more information sources bleeding into the source being used? Crosstalk..

Usually through a  point to point preamp, with no RCA crosstalk caps.

Yes crosstalk is considered BAD. But pretty easy to fix. Crosstalk caps

Is there another type of crosstalk?

Differential as opposed to non differential? definite channel separation there..Left volume, right volume, no balance circuit, usually good indicator.

Regards

Staying within the scope of your tiny little window, amplifiers only, crosstalk isn’t hardly even relevant. This would be different of course if there were amplifiers with huge amounts of crosstalk. But that’s the thing. Crosstalk per se is only really relevant or significant when it starts to fall outside a certain range. Which nobody really knows what that is. But that’s the problem with specifications. Nobody really knows.

The thing of it is, if you want to begin to understand the full depth and nature of the misconception here, then think of this: you can get a really solid image from an amplifier with 100% crosstalk. A mono amp. The same exact signal going to both speakers will throw a perfect center image.

Now imagine the same amp only it now has a lot of separation, but still has some crosstalk, and instead of a center image we’re listening to a singer standing ten feet left of center. Everything else with our imaginary amp is absolutely perfect. Everything but the tiny little bit of crosstalk.

So what happens? Almost all the signal is telling us the singer is on the left. Only a tiny little bit is telling us she’s on the right. To the extent that tiny little bit matters it will pull her image a bit to the right. But also at the same time a little bit of the right side is leaking over into the left. Actually the same amount is trying to pull her image each way. So the result is a bit of smearing or loss of focus.

How much crosstalk before this becomes a serious issue? This is where your question is so narrowly focused it almost guaranteed a bad answer. Because phono cartridges have the worst crosstalk numbers in the world, orders of magnitude worse than amplifiers, CD players, just about anything else. Yet my cartridge with its lousy crap crosstalk somehow manages to throw a rock solid palpable wide and deep sound stage that would have you drooling and shaking your head in amazement.

How much crosstalk does my Melody amp have? I don't know. I have no idea. Absolutely none. Its probably in there somewhere. I just can't be bothered with such things. Too irrelevant. I deal with what matters. This ain't it.

Kind of a long way around but that’s how hard it is sometimes to show just how far off base a lot of these conventional wisdom ideas really are. Not your fault. Everyone parrots this stuff so much, so few bother to stop and think things through, its what makes this such a hard thing to do.

The prerequisite for sound stage is room acoustics.

I have found that the sound stage is directly tied to the room treatment.  Want height? Treat the floor and ceiling.  Depth? Treat the wall behind and in front of the speakers.  

Do this experiment on your own.  Put your speakers out into the room and set your chair 3' from them.  What you are losing from that to your normal seating position is due to room acoustics.

I always recommend GIK Acoustics, and they are having a sale. :) Talk to them.