Point to Point wiring

[Jocko Homo]

Quit giving away all my good ideas. Remember, these are probably the same guys who claim they really are learning something in bootcamp.

Let'em learn the hard way.

Jocko

[jduncan]

uh, are you serious jocko?

[Keithj]

Originally posted by HarryHaller
R paralleled with L on signal line only. Computer models, TDR, listening test..... it works real well. Resistive pads are great too if you have enough amplitude signal to pad 6 to 10 dB in the cable. Jocko is an advocate of resistive pads as well. Mechanical damping is a big deal for digital cables as well. I have built hundreds of digital cables, BNC, RCA, and balanced with XLR with networks and even DC bias on the cable's dielectric.

H.H.

Hmmm, I'm interested in this. Let's explore... Posit a short piece of coaxial cable carrying a 2MHz nominal square wave. This wire is about 1 metre long and made of reasonable coax. The source impedance is 75 ohms, the terminating impedance is 75 ohms, the cable is 75 ohms as are the connectors. So,
1. How does a pad (whether L or PI) provide a better termination than a 75 ohm resistor? Or is the reduced level of the signal somehow allowing the receiver to , at the end, resolve the audio more accutately? For example, through better clock recovery?
2. I can see that, under some circumstances, this combination may ring. As long as the ringing voltage is low, the receiver will effectively remove it. How will R||L improve the situation?
3. Is the signal produced by the TDR of the same rise time and duty cycle as the 2MHz signal I'm trying to transfer?

Personally I see more problems with clock recovery in such a system than with the types of cable as long as those cables are of good quality. I do acknowledge that many cables of varying types are made to transfer different types of signal from special low noise all the way to heavy mains cables, they are made for the transfer of signals of various types, currents and voltages.

Keep on experimenting. When are you publishing the results and having them peer reviewed. You see, you've made a number of statements that may assist in advancing the art. Let's test your ideas through peer review...... AES maybe?

regards, Keith

[Keithj]

Originally posted by dice45
Keith,

(Lots removed...)

Concerning, TT, keep the Grace arm and stay tuned on coming TT threads as soon as Jason opens us a TT forum!

Trouble is.... I'm having trouble finding belts for the TT (It's a TD 160S, not a TD 128) and the needle is starting to wear. The bloke who built Van Den Hul cartridges in Melbourne now rebuilds cartridges (or did up to 6 months ago - but the prices (weeps into the glass of Grand Echezeaux)

biased me, no question, red sounds best to my ears (the brain immediately translating this to ultra-dark-red Bordeaux wines) no question for me, good Bordeaux' are unequalled AFA the whole scope of properties of a great wine is concerned. Yes, there a facny Californians and south african and Australians, but .. they are fancy in some respects and flawed in others .... I prefer great Bordeaux and would dare to state that up to a price of 40$ a bottle one gets fair exchange for the money and does not even pay for the badge. Above that (referring to German prices), the return on investment ceases to look good.

Ah, the good bit. I've just been to two of New Zealand's prime wine growing areas, Hawkes Bay and Martinborough. HB is the home to excellent chardonnays and various reds (except pinot noir), while Martinwossname is the home to excellent pinot noirs. I've been tasting some of these. Lovely stuff, more finesse in the chardonnays than most Australians. Pinots - lovely stuff. I picked up a thing called Dry River Amaranth Pinot Noir. Beautiful...it'll stay away for at least 5 years.

It's our 30th wedding anniversary in a week. I have two bottles for that... A 1983 Bouchard Pere et Fils Le Montrachet and a trockenbeerenauslese what I have forgotten the make of.

I'm looking seriously at some modern French wines. Now they've taken to new world production techniques (stainless steel, hygiene) even the cheaper wines like the Vin de Pays can be good stuff. NZ$16 (US $6) buys really good stuff.

Whoops, this is seriously off topic. The sound system for this party will be.....

regards, Keith

P.S. How about a forum on the auditory effects of drinking seriously good wines in wonderful company.





Harry,


gorgeous pix ! What a radiating charisma! [/QUOTE]

[mrfeedback]

Hello Harry,

R paralleled with L on signal line only. Computer models, TDR, listening test..... it works real well. Resistive pads are great too if you have enough amplitude signal to pad 6 to 10 dB in the cable.

R//L on active line would cause HF rolloff, yeah ?
How does this help ?
Resistive pad - L type pad, T type pad, balanced variant, unbalanced variant ?
With your TDR testing, what results or changes in the recieved signal are you getting.
Theoretically, with 75 ohm source, cable, connectors and termination there should not be reflections, yeah ?
How much return loss are you seeing with your TDR testing, on the usual setups ?
Interested to know.

Regards, Eric.

[HarryHaller]

Those idiots at the AES are the reason that we have have digital cables with RCA and XLR connectors in the first place. They don't have a clue...... I'll can hardly wait till Jocko weighs in on this one.

The network is for RCA connectors, since the AES thinks that RCAs can go on digital cables. They also cursed us with 0.5 volt levels.

I have been reviewed by my peers; Jocko, Scott Nixon, several audio reviewers, and hundreds of paying customers.

I have done TDR with HCMOS logic typical of drivers.

Correctly designed networks don't ring.

1 meter is not a good length for a digital cable and a half meter is even worse.

There is no such thing as an ideal 75 ohm cable. Gore will sell you something they think is close for $180 a foot but it will make a bad sounding digital cable.

I guess Jocko is right. I will have to let them learn the hard way on this one. By the way the network is propietary since I sold it to an audiophile cable maufacturer. It could be designed by someone with a little desire and a 100MHz scope. I will put on my asbestos long johns and wait for the smoke and fire now.....

H.H.

[Jocko Homo]

(I really love this job. Too bad I can't get paid for it.)

jduncan:

Serious, about what? Let me know. I probably am serious.

Keithj:

1.) Reflections go both directions. Has nothing to do with RX levels. No more hints.

2.) Buy a book on transmission lines.

z=sqrt(L/C) Last hint.

3.) TDRs have rise times, in the case of mine, of around 100 pS.

Too bad you don't know Albert Porter. Only he would debate you on how single-malt Scotch affects this stuff. Come to Dallas some Tuesday night......I'm sure he would love to have you there.

Anyway......

The AES are IDIOTS. Anyone with a good background in RF would know you can't make a system with.......what was it......5 transmitters and 7 receivers.....all daisy-chained.....using XLR connectors!

XLR connectors! The only thing in audio worse for RF than stinking RCAs.

mrfeedback:

No, it doesn't cause rolloff. See number 2 above.

A pad is a pad is a pad. No more clues for you either.

On my TDR, with my you-know-what on it, the input rho is 0.04. Or for those of you who are the product of the lousy US educational system.........that is about 28 dB return loss. (Those of you in Rio Linda......go back to sleep....Rush is not on yet.) Which is less than the difference you will see if you put a 50 ohm BNC where a 75 ohm one belongs. It is caused where the center conductor breaks out of the shield. There are ways around that, but I wasn't in the mood that day to buy a $18 connector.

OK.......obvious joke............

"What kind of mood are you in today, butt-hole?"

Obvious answer........foul, as ususal. There......saved of you all the bother of being the first to say it. (Who said I'm not a nice guy?)

If you want to use GoreTex, for some bizarre reason the 50 ohm stuff sounds better. Really tight bass, but messed up highs.

And once you get by the cable reflection problem.........then there is the input circuit reflection problem.

Which is why I HATE those Crystal receivers. Once, again, designed by idiots with no background in RF.

But don't believe me..........keep on using 1/2 meter cables with RCAs. While you are at it, put a low-pass filter in front of it, you'll enjoy it better. (Don't laugh, some BIG NAME outfit did. They also offered me a job to redesign their entire line after it stopped selling.)

Hey Hairy........do you think we should move this to the digital forum, where we can enrage a whole lot more people? I think I sense the need for another "new law" rant............

Hmmmmm.....I think I even see a way to make money on this one.

Jocko Homo, Il Duce di TDR

[Keithj]

Originally posted by Jocko Homo
Promitheus:

Yes. Reflections cause jitter in the recovered clock, which leads to all sorts of nasty sounds in the HF spectrum, and possibly loose, flabby bass.

Jocko

I was troubled by somethings. This statement is one of those somethings.....

You say that jitter causes all sorts of nasty sounds in the HF spectrum and possibly loose flabby bass. Do you have a mechanism for this, particularly the seemingly "bandidness" of the effect? It seems to me that, as the signal from the CD transport is bits with no audio signal modulated onto it that there is no way you can divide the audio spectrum up in such a way. This means that if there are problems in the digital transport or jitter or whatever that the entire audio band would be affected.

Comment?

regards, Keith

[Keithj]

Originally posted by HarryHaller
Those idiots at the AES are the reason that we have have digital cables with RCA and XLR connectors in the first place. They don't have a clue...... I'll can hardly wait till Jocko weighs in on this one.

Hmmm. I was accused of rudeness by someone a while ago. This is an ad hominem attack and by definition also rude. Justify it. Did the AES say you can have RCA connectors, did the manufacturers or did a contributor to the AES say it? Cite references if you are able.

The network is for RCA connectors, since the AES thinks that RCAs can go on digital cables. They also cursed us with 0.5 volt levels.

See above. What's the problem with 0.5 volt levels? Is the noise immunity a bit too low?

I have been reviewed by my peers; Jocko, Scott Nixon, several audio reviewers, and hundreds of paying customers.

I'm not dismissing this, after all if lots of people are happy with their cables then great. However all this seems to be anecdotal with all the known problems of anecdotal results.

Correctly designed networks don't ring.

Poor choice of words. The signal suffers from high frequency rolloff and the influence of noise. This, as you know, can result in confusion for the receiver of the decision points in the data.

1 meter is not a good length for a digital cable and a half meter is even worse.

Why not? From my decidedly faulty memory, a piece of cable doesn't become a transmission line until it's an appreciable part of a wavelength long, say 1/4 lambda. At 2MHz, assuming a propagation constant of around 0.7 that's around 100 metres. (I've forgotten the frequency of the data between a CD transport and the DAC system).

There is no such thing as an ideal 75 ohm cable.

Ah, here we agree. So, do your networks go at the CD end of the cable or at the DAC end or both?

I guess Jocko is right. I will have to let them learn the hard way on this one. By the way the network is propietary since I sold it to an audiophile cable maufacturer. It could be designed by someone with a little desire and a 100MHz scope. I will put on my asbestos long johns and wait for the smoke and fire now.....

Nah. Just seeking to learn.....

H.H.

regards, Keith

[Jocko Homo]

keithj:

Who said you were rude? Let me at them.........I'll show them rude.

I think the AES used 5 volt levels at one time, if I am right. Great.....just what we need......tons of EMI.

The whole problem here with reflections is that the clock is recovered from this serial data stream. Reflections do cause jitter on the recovered clock signal, plain and simple. Jitter affects the higher frequency spectrum more than the lower. I suspect the problem with the bass has to do with pyschoacustics, something I know almost nothing about.

I go back to my previous post: reflections travel in both directions. Where the reflection lands is more of a problem than how much it is. This is not anecdotal jibber-jabber. It is fact. And short cables make things worse.

I put networks on both ends. See above.

Speaking of how short cables are worse...............single-mode fiber! Anyone who uses a 1 meter fiber cable on one of those "AT&T" fiber TX/RX combos never called them to find out why IT IS NOT DESIGNED TO WORK THAT WAY. But people made them. Audiophiles bought them. And I demonstrated how rotten they sounded. And made them sick when I could take a Belden coax that only cost 10 cents/foot that sounded better. Same problem, different mechanism.

Any more questions? What is that they say at "Rat Shack": "You got questions, we got answers." No sounds to me like they have worse grammar than I do.

Jocko