Synergy?

[microstrip]

My two cents:

If you want to debate compatibility and synergy, first you have to define what is the object of your discussion - what you need the c&s for.

Since you debate SPDIF what are your final concerns: 1. jitter, 2. data loss, 3. generation of spurious RF due to reflections in mismatched cables, plugs and terminations? 4. Something else?

 

[jkeny]

Not sure I get what you're saying -- is this primarily or exclusively a problem with SPDIF/RCA devices? I can get an idea of how common the problem is by estimating how common RCA coax interfaces are?

Follow the logic, Tim. I said RCA connectors are not 75ohm. So the obviously visible sign that a device is not 75ohm is if it uses RCA as a SPDIF connector. There will be other devices too that don't meet 75ohms but you would have to measure to find out. A rough count of digital analogue devices with RCA SPDIF connectors will show that a large portion of manufacturers fall foul of the specs!

I did a quick Google of RF attenuators and looked at some products. I see variable, fixed, in different values. I would assume...though guess might be more accurate...that I'd need a 75 ohm fixed attenuator? On the 3 sites I checked, I didn't see any RCA examples, only BNC. But with all of that said, yes, I'd like to try it.

Did you follow the link I already gave to where I mentioned this before? The product code is given there. yes, you will also need a BNC/RCA adapter because these RF attenuators are not made with RCA connectors

A question, though. This is a passive, resistive device, correct? Does it not affect the waveform? Are we sure we're not trading problems?

I'll take your insistence that I'm playing as a compliment, John, but seriously, my technical knowledge is pretty limited. I'm inquiring.

Tim

I've no problem with someone asking questions, as long as they read & think about the answers. Clarifications are fine once they show that some thinking has been attempted. I & others are not here as an unlimited source of deep level information (I certainly would not put myself forward as a font of that type of knowledge). Some is given, some is held back & some require the answer I'm going to now give to your last question about waveform - try it & see!! If it improves the sound will this answer your question?

 

[jkeny]

My two cents:

If you want to debate compatibility and synergy, first you have to define what is the object of your discussion - what you need the c&s for.

Since you debate SPDIF what are your final concerns: 1. jitter, 2. data loss, 3. generation of spurious RF due to reflections in mismatched cables, plugs and terminations? 4. Something else?

I'm trying not to debate it & suggesting that it just be tried. The analysis can come later if there is an interest but on another thread, I would suggest.
I just gave it as an example of adequate operation (compatible) Vs optimal operation

 

[Phelonious Ponk]

Follow the logic, Tim. I said RCA connectors are not 75ohm. So the obviously visible sign that a device is not 75ohm is if it uses RCA as a SPDIF connector. There will be other devices too that don't meet 75ohms but you would have to measure to find out. A rough count of digital analogue devices with RCA SPDIF connectors will show that a large portion of manufacturers fall foul of the specs!

That's the logic I followed, John, I just wanted confirmation. I thought that might be a good thing, given that while the problem seems to be highly concentrated in RCA connectors, all the attenuators seem to be for BNC connectors. That was confusing.

Did you follow the link I already gave to where I mentioned this before?

No, I missed that. I'll go find it, thanks.

you will also need a BNC/RCA adapter because these RF attenuators are not made with RCA connectors. I've no problem with someone asking questions, as long as they read & think about the answers. Clarifications are fine once they show that some thinking has been attempted.

I did think, John. I thought you had said that the problem was primarily with RCA connectors, then searched for the solution and found it exclusively addressed BNC connectors. Follow the logic, John, there is an obvious disconnect there that called for a follow-up question.

One more question, if you don't mind too much -- my USB>X converter will output BNC. I'm going to have to use a BNC>RCA adapter anyway. Would it be better/worse to change to a BNC cable and adapt at the DAC input? Or will my current RCA cable with the BNC adapter and RFI attenuator do just as well?

Tim

 

[jkeny]

I did think, John. I thought you had said that the problem was primarily with RCA connectors, then searched for the solution and found it exclusively addressed BNC connectors. Follow the logic, John, there is an obvious disconnect there that called for a follow-up question.

Hold on Tim, The problem is with RCA connectors - the correct answer is to replace them & ensure your impedance is correct all the way from transmitter to receiver. So in the absence of doing this we use a add-on connector which is BNC format. Yes, we now need to add a BNC/RCA adapter but if the solution is meant to address the impedance mismatch (RCA is the obvious visible sign of this but there are lots of other ways that the impedance can be less than exemplary) then will it not also work if there is an extra RCA connector added into the sea of already mismatched impedances? Again, we could debate this all day - try it & see is my answer & then ask questions!!

One more question, if you don't mind too much -- my USB>X converter will output BNC. I'm going to have to use a BNC>RCA adapter anyway. Would it be better/worse to change to a BNC cable and adapt at the DAC input? Or will my current RCA cable with the BNC adapter and RFI attenuator do just as well?

Tim

Use your current cable + RF attenuator. Now the big question - what value of attenuation will work? Too much & the SPDIF receiver will will not lock to too low a signal, too little & you minimise the effect, making it of no use. The ideal is to get as much attenuation as you can before the signal becomes too low. There is no way of calculating this, it depends on too many variable. I would suggest getting two RF attenuators of different values & I would guess that the best value will be -15dB so you might want to get a -5dB & -10dB. That will give you the choice of applying -5, -10, -15dB depending on the combinations used - yes you can put two in series

 

[Mike Lavigne]

Too bad DartZeel coudn't have "implemented" it's SE or Balanced connections as well.

there are very good reasons darTZeel did not go that way. read Herve's November 2001 article on electronic reflections in cables. those other interface directions have fundamental limitations according to Herve's study as i read it.

it's not that they don't work well; just not ideally.

 

[jkeny]

there are very good reasons darTZeel did not go that way. read Herve's November 2001 article on electronic reflections in cables. those other interface directions have fundamental limitations according to Herve's study as i read it.

it's not that they don't work well; just not ideally.

Mike, the Dartzeel stuff confuses me! When you first mentioned it 50ohm BNC "Zeel" connectors, I thought that this was SPDIF done out-of-spec but with a matching 50 ohm cable & 50ohm receiver end. This is what I was referring to as a marketing trick that some manufacturers have done, I believe. Their equipment sounds best when used with the supplied cable & devices because they are all manufactured to match this out of spec setting.

Now, Dartzeel, aren't using 50ohm on SPDIF but on analogue connections, it would appear. I'm not saying it doesn't have benefits, maybe it does but reflections from impedance mismatches are not something that occur in low speed analogue signals, AFAIK. it requires transmission line effects to come into play & these only occur at high speeds! So I will read that Nov 2001 article with interest & maybe learn something new or maybe learn something about the writer

Edit: Hmm, just read it - there are no graphs showing reflections at audio analogue speeds which I think says a lot about the claims

 

[Phelonious Ponk]

Hold on Tim, The problem is with RCA connectors - the correct answer is to replace them & ensure your impedance is correct all the way from transmitter to receiver. So in the absence of doing this we use a add-on connector which is BNC format. Yes, we now need to add a BNC/RCA adapter but if the solution is meant to address the impedance mismatch (RCA is the obvious visible sign of this but there are lots of other ways that the impedance can be less than exemplary) then will it not also work if there is an extra RCA connector added into the sea of already mismatched impedances? Again, we could debate this all day - try it & see is my answer & then ask questions!!

Use your current cable + RF attenuator. Now the big question - what value of attenuation will work? Too much & the SPDIF receiver will will not lock to too low a signal, too little & you minimise the effect, making it of no use. The ideal is to get as much attenuation as you can before the signal becomes too low. There is no way of calculating this, it depends on too many variable. I would suggest getting two RF attenuators of different values & I would guess that the best value will be -15dB so you might want to get a -5dB & -10dB. That will give you the choice of applying -5, -10, -15dB depending on the combinations used - yes you can put two in series

Thanks, John.

Tim

 

[MylesBAstor]

Mike, the Dartzeel stuff confuses me! When you first mentioned it 50ohm BNC "Zeel" connectors, I thought that this was SPDIF done out-of-spec but with a matching 50 ohm cable & 50ohm receiver end. This is what I was referring to as a marketing trick that some manufacturers have done, I believe. Their equipment sounds best when used with the supplied cable & devices because they are all manufactured to match this out of spec setting.

Now, Dartzeel, aren't using 50ohm on SPDIF but on analogue connections, it would appear. I'm not saying it doesn't have benefits, maybe it does but reflections from impedance mismatches are not something that occur in low speed analogue signals, AFAIK. it requires transmission line effects to come into play & these only occur at high speeds! So I will read that Nov 2001 article with interest & maybe learn something new or maybe learn something about the writer

Edit: Hmm, just read it - there are no graphs showing reflections at audio analogue speeds which I think says a lot about the claims

Although there are no graphs and some of this may be unique to Spectral with its ultra-wide bandwidth design, Keith also talks about interactions esp. with crossovers and reflections.

Johnson: It's always essential to have a fully-integrated or fully-interfaced system. The ideal power amplifier would be one that in no way can interact with the speaker crossover. In other words, whenever you hook the amplifier to the loudspeaker, the speaker's crossover and drivers behave as if you haven't changed anything. Yet a power amplifier that's very fast is going to put out some very high frequencies. The speaker cable bust be able to damp or absorb those frequencies without causing reflections or rebound from the unknown parts that are inside the loudspeaker.

That requires a special cable. In other words, the faster the amplifier, the more one has to be very careful about the cable connecting the speaker. In a system approach, the advantage is that the cable is done right. The speaker sees virtually the zero or defined impedance that the crossover was designed with. A cheap cable might have inductance which will actually detune some of the parts within the crossover and make the crossover behave differently. A very small change of inductance in the cable can make a big difference in what's happening inside a speaker. By building all these parts as a system, the interactions are designed out and the whole thing simply works better. [/COLOR]

 

[jkeny]

Although there are no graphs and some of this may be unique to Spectral with its ultra-wide bandwidth design, Keith also talks about interactions esp. with crossovers and reflections.

Johnson: It's always essential to have a fully-integrated or fully-interfaced system. The ideal power amplifier would be one that in no way can interact with the speaker crossover. In other words, whenever you hook the amplifier to the loudspeaker, the speaker's crossover and drivers behave as if you haven't changed anything. Yet a power amplifier that's very fast is going to put out some very high frequencies. The speaker cable bust be able to damp or absorb those frequencies without causing reflections or rebound from the unknown parts that are inside the loudspeaker.

That requires a special cable. In other words, the faster the amplifier, the more one has to be very careful about the cable connecting the speaker. In a system approach, the advantage is that the cable is done right. The speaker sees virtually the zero or defined impedance that the crossover was designed with. A cheap cable might have inductance which will actually detune some of the parts within the crossover and make the crossover behave differently. A very small change of inductance in the cable can make a big difference in what's happening inside a speaker. By building all these parts as a system, the interactions are designed out and the whole thing simply works better. [/COLOR]

OK, so are you in agreement about Dartzeel's 50ohm matching in analogue cables being a Macguffin(as Hitchcock would say)?

Reflections from speaker crossovers is a whole other ballgame & doesn't fall into analogue interconnects. Yes, I agree that amplifier output stages need to be immune to back-reflections from speaker crossovers! And yes, I agree that there are probably optimal amplifier/cable/speaker combinations but I would also strive towards devices that were built to be immune to these interactions so no "synergy" needed

 

[Mike Lavigne]

Mike, the Dartzeel stuff confuses me! When you first mentioned it 50ohm BNC "Zeel" connectors, I thought that this was SPDIF done out-of-spec but with a matching 50 ohm cable & 50ohm receiver end. This is what I was referring to as a marketing trick that some manufacturers have done, I believe. Their equipment sounds best when used with the supplied cable & devices because they are all manufactured to match this out of spec setting.

Now, Dartzeel, aren't using 50ohm on SPDIF but on analogue connections, it would appear.

the 'zeel' interface uses BNC connections.

I'm not saying it doesn't have benefits, maybe it does but reflections from impedance mismatches are not something that occur in low speed analogue signals, AFAIK. it requires transmission line effects to come into play & these only occur at high speeds! So I will read that Nov 2001 article with interest & maybe learn something new or maybe learn something about the writer

or.......maybe just listen to darTZeel gear using the 'zeel' interface.

Edit: Hmm, just read it - there are no graphs showing reflections at audio analogue speeds which I think says a lot about the claims

the Stereophile article has lots of WBF techie graphs, you'll love it.

 

[andromedaaudio]

About spectral
What does audio have to do with extremely high freq 100 khz would be more than fine , the mit i opened up was nothing more than a tone control blocking high freqs , why that should be neutral combined with spectral is a mysterie to me , same as the amp shouldnt change the crossover , sounds like very vague and mysterious marketing .
Usually the amp will distort before the speaker , the more power/currentdelivery the amp has the more the unit is forced to follow the signal , what is in the crossover is something different and should work optimal regardless of ampbrand.

Just my opinion , dont take it to serious

Ps MIT might work with a speaker with tilted treble output to achieve flat /damped high freq

 

[jkeny]

the 'zeel' interface uses BNC connections.

Yes, I know, that's not what I was confused about - I couldn't believe they were talking about analogue interconnects

or.......maybe just listen to darTZeel gear using the 'zeel' interface.

Sure, got a spare $20,000? There may well be an improvement but is it due to the impedance matching is the question

the Stereophile article has lots of WBF techie graphs, you'll love it.

http://www.breem.nl/fldtechniek/pgdeletraz.htm
But these graphs don't have anything to do with analogue audio speeds!
For transmission line effects (reflections) the electrical length of the cable has to be close to the wavelength. In the case of a 10kHz wavelength the cable would need to be about 20Km to have any effect not 1m. See here http://www.allaboutcircuits.com/vol_2/chpt_14/1.html

 

[jkeny]

The biggest flaw in that article seems to me to be fig 10 & the following explanation. Fig 10 shows what he claims are echoes spaced apart by 500nS, the propagation time of a 100M cable. These echoes, he claims, are causing a rounding off of the square wave (let's just ignore for the moment, the square waves' appropriateness to analogue audio). Now if we reduce the cable to a realistic 1M we have 100 times less propagation time i.e 5nS. Is a 5nS disturbance of a couple of mV of consequence? Maybe I'm wrong in my analysis but he doesn't address these issues which I expect a thorough treatment would if he want to support the claim.

 

[Ethan Winer]

What does audio have to do with extremely high freq 100 khz would be more than fine

This is the key. All sorts of properties that exist at radio frequencies, such as skin effect and VSWR, are irrelevant at audio frequencies. Yes, an impedance mismatch at connection points causes reflections and electrical standing waves. At 100 MHz this is an important consideration for maximizing power transfer. But it doesn't matter at audio frequencies, or even at the 2x audio frequencies used for digital signals. I've connected audio gear via S/PDIF many times using whatever random RCA cables I had lying around, and it never made any difference.

--Ethan

 

[jkeny]

This is the key. All sorts of properties that exist at radio frequencies, such as skin effect and VSWR, are irrelevant at audio frequencies. Yes, an impedance mismatch at connection points causes reflections and electrical standing waves. At 100 MHz this is an important consideration for maximizing power transfer. But it doesn't matter at audio frequencies, or even at the 2x audio frequencies used for digital signals. I've connected audio gear via S/PDIF many times using whatever random RCA cables I had lying around, and it never made any difference.

--Ethan

Again Ethan, you deal in half-truths or maybe you don't understand what your saying?
Yes analogue signals are pretty immune to these effects but do you really think that the max bandwith in SPDIF is 2X 20KHz? You need to read some more, my man!!

 

[MylesBAstor]

About spectral
What does audio have to do with extremely high freq 100 khz would be more than fine , the mit i opened up was nothing more than a tone control blocking high freqs , why that should be neutral combined with spectral is a mysterie to me , same as the amp shouldnt change the crossover , sounds like very vague and mysterious marketing .
Usually the amp will distort before the speaker , the more power/currentdelivery the amp has the more the unit is forced to follow the signal , what is in the crossover is something different and should work optimal regardless of ampbrand.

Just my opinion , dont take it to serious

Ps MIT might work with a speaker with tilted treble output to achieve flat /damped high freq

Not sure which MIT cables you heard, but the ones I had (Oracle MA-X phono and ICs and Magnum speaker) in house would far from work with a "tilted treble." Actually with the MIT, WYHIWYG. It's far from a tone control and is quite possibly among the best cables I've heard in my system. Neutral, resolving, terrific sense of space and harmonics, great 3D and unmatched low end is how I would describe the MIT cables. In fact, I wouldn't use MIT in a bright system because the aberration will be ruthlessly revealed.

 

[Ethan Winer]

Again Ethan, you deal in half-truths or maybe you don't understand what your saying?

Are you unable to have a technical discussion without being insulting?

do you really think that the max bandwith in SPDIF is 2X 20KHz?

Even with a sample rate of 96 KHz the effects of impedance mismatching in RCA connectors is irrelevant. And if someone uses a higher frequency for whatever reason, any problems they create are their own fault and probably deserved.

--Ethan

 

[jkeny]

Are you unable to have a technical discussion without being insulting?

Apologies if you were insulted but I'm kinda direct, like you, I guess & tell it like I see it?

Even with a sample rate of 96 KHz the effects of impedance mismatching in RCA connectors is irrelevant. And if someone uses a higher frequency for whatever reason, any problems they create are their own fault and probably deserved.

--Ethan

Are you claiming this: "2x audio frequencies used for digital signals."? Let's clear this up first before moving on to the next technical part of the discussion

 

[NorthStar]

Again Ethan, you deal in half-truths or maybe you don't understand what your saying?
Yes analogue signals are pretty immune to these effects but do you really think that the max bandwith in SPDIF is 2X 20KHz? You need to read some more, my man!!

Hi John,

You're a good guy, and with great knowledge, and you are also my friend;
and because indeed you are my friend I have to be truthful with you:
... You are talking to Ethan (tone) as if he was one of an inferior human species, or a child.

Well, I think you know what I mean ... :b

Regards,
Bob

P.S. Perhaps a little 'synergy' with Ethan can go a long way.