Hi GreggeryPeccary,
If you want a book, your local library should have some good ones. There are plenty of free downloads on the web too (as poobah pointed out).
-Chris
If you want a book, your local library should have some good ones. There are plenty of free downloads on the web too (as poobah pointed out).
-Chris
I thought I'd post a followup.
Below are measurements of impedances when interconnects are connected to a receiving device.
An externally hosted image should be here but it was not working when we last tested it.
Further is a cable being tested.
An externally hosted image should be here but it was not working when we last tested it.
For some reason imageshack does not always show the pic for me now. Wonder if it's the same for others?
Do you know where the standard for XLR connections can be found?
a central enabling invention for long distance telephone networks was Black's Negative Feedback Amplifier
http://people.tamu.edu/~just4uvivek/ECEN605/LECTURE1/Harold_1927.pdf
another view:
http://mit.edu/6.933/www/black.pdf
for a little lighter reading:
http://www.amazon.com/Telephone-Gambit-Chasing-Alexander-Graham/dp/0393062066
Last edited:
Jensen Transformers and RANE have papers and app. notes on XLR connectors.
Rod Elliot just edited a nice paper of Bill Whitlocks many papers on balanced circuits.
Design of High-Performance Balanced Audio Interfaces
Balanced Interfaces
Rod Elliot just edited a nice paper of Bill Whitlocks many papers on balanced circuits.
Design of High-Performance Balanced Audio Interfaces
Balanced Interfaces
" ... For some reason imageshack does not always show the pic for me now. Wonder if it's the same for others? ..."
ImageShack deletes pictures after a certain time period if you are not an active user ... logging in regularly, adding photos regularly, etc.
For use in a forum like this, image hosting sites are generally worthless. The images won't be there in six months in most cases.
If you want the image to last for future readers of this or any other forum, reduce it to about 100k file size jpeg and upload it with the tools available in every comment window.
RE: XLR
The thing about XLR is you have to know the history of the connector. It's a proprietary connector introduced by Canon. There is an evolution of connectors; there were different ones prior to the X connector, which was followed by the XL connector, etc.
X had the round shape and compact size. XL added the locking mechanism ("X with Latch"). For the most part, people refer to the XL connector as XLR.
A true Canon XLR has the female connectors only encased in a compound called "Resilient Polychloroprene"; hence the XLR.
Most of what we refer to as XLR do not have any "R" in them, if you will.
In 1950, Ampex adopted the XLR connection and wired pin 1 ground, pin 2 signal return and pin 3 signal hot.
This practice was copied by manufacturers in the USA only, and was later still embodied in the AES14 standard. The same AES standard also defined male connectors as outputs and female connectors as inputs, opposite of worldwide practice at the time.
Elsewhere in the world, companies continued to wire pin 1 ground, pin 2 signal hot and pin 3 signal return, and continued to use males for inputs and females for outputs. In essence, it's was a refusal to change to the Ampex method "just because", since it would create incompatibilities with existing products, whether from that manufacturer or others.
In 1975 what is now known as "pin two hot" method was adopted worldwide for microphone use by the IEC (Publication 268, Part 12), and the AES did not object to the adoption worldwide including the USA for microphones. Pin 2 hot was also adopted by the SMPTE (motion picture industry) for all uses under standard RP-134-1986, followed by the European Broadcast Union in 1988. The AES revisited the issue and found the majority of it's members were using pin 2 hot, so revised AES14 to that in 1990.
So, everyone should be wiring pin 2 hot these days.
Regardless, the worst case scenario is a reversal of signal phase.
ImageShack deletes pictures after a certain time period if you are not an active user ... logging in regularly, adding photos regularly, etc.
For use in a forum like this, image hosting sites are generally worthless. The images won't be there in six months in most cases.
If you want the image to last for future readers of this or any other forum, reduce it to about 100k file size jpeg and upload it with the tools available in every comment window.
RE: XLR
The thing about XLR is you have to know the history of the connector. It's a proprietary connector introduced by Canon. There is an evolution of connectors; there were different ones prior to the X connector, which was followed by the XL connector, etc.
X had the round shape and compact size. XL added the locking mechanism ("X with Latch"). For the most part, people refer to the XL connector as XLR.
A true Canon XLR has the female connectors only encased in a compound called "Resilient Polychloroprene"; hence the XLR.
Most of what we refer to as XLR do not have any "R" in them, if you will.
In 1950, Ampex adopted the XLR connection and wired pin 1 ground, pin 2 signal return and pin 3 signal hot.
This practice was copied by manufacturers in the USA only, and was later still embodied in the AES14 standard. The same AES standard also defined male connectors as outputs and female connectors as inputs, opposite of worldwide practice at the time.
Elsewhere in the world, companies continued to wire pin 1 ground, pin 2 signal hot and pin 3 signal return, and continued to use males for inputs and females for outputs. In essence, it's was a refusal to change to the Ampex method "just because", since it would create incompatibilities with existing products, whether from that manufacturer or others.
In 1975 what is now known as "pin two hot" method was adopted worldwide for microphone use by the IEC (Publication 268, Part 12), and the AES did not object to the adoption worldwide including the USA for microphones. Pin 2 hot was also adopted by the SMPTE (motion picture industry) for all uses under standard RP-134-1986, followed by the European Broadcast Union in 1988. The AES revisited the issue and found the majority of it's members were using pin 2 hot, so revised AES14 to that in 1990.
So, everyone should be wiring pin 2 hot these days.
Regardless, the worst case scenario is a reversal of signal phase.
Last edited:
Nice paper, but is there a standard as to what the interface i/o impedances should be? Different numbers are mentioned, so I was wondering whether anyone is a standard now. If it's 20K that's in the examples, then there might be some interesting issues with that.
I'm not aware of any standards for impedances or impedance ratios.
Good engineering practices suggest that the input impedance be 10 to 20 times the (driving) output impedance.
In the distant past we had matched 600/600 Ohm Input/Output circuits, but they faded away in the 1960's.
Good engineering practices suggest that the input impedance be 10 to 20 times the (driving) output impedance.
In the distant past we had matched 600/600 Ohm Input/Output circuits, but they faded away in the 1960's.
This is where one deficiency is, As shown in my previous graphs, the cable characteristics causes the impedance to very significantly over the audio range. I wonder why this was never addressed. Maybe everyone were satisfied with what they hear.😉
There seems to be more money to be made without the proper interface so that marketing can say whatever they want to explain the difference.
There seems to be more money to be made without the proper interface so that marketing can say whatever they want to explain the difference.
Are you talking about the graphs a few post back with no vertical axes and no information on test setup? I saw them, but have no idea of how to interpret them. If there was an earlier post that clears this up, could you let me know where it is? Thanks!
I would like to see other measurements done by anyone in this forum to see whether it differs from what I measured regardless of setup before we go into any further discussion. Basically just connect cable to an amp input and measure the impedance from the source end. Should not be difficult for anyone DIYing speakers etc. Also read the OCOS report.
I've measured Monsters, MITs, Magnans, Radall Research, Alpha Core etc.
I've measured Monsters, MITs, Magnans, Radall Research, Alpha Core etc.
Last edited:
I don't have time to read this whole thread so appologies if this has already been stated.
In my experience the quality of the connectors, and espescially the quality of the connection between the connector and cable, as well as obviously the quality of the connector-to-connector conection plays a far more significant role than the cable itself (provided the cable at least meets international standards).
A quick, cut to the chase story: A while ago I paid big bucks on some cables with BNC connectors. I spent 3 months trying to sort out what the problem was (I was having a problem). I finally discovered the crimped connectors were not good enough, that is the crimping was not adequate even though it passed the industry standards for crimping. I immediately cut the bnc connectors off and replaced them with bnc connectors that could be soldered. After that, problem solved. This is just one of many stories I could tell you about poor connections (and all of them were not obvious problems).
Edit:
I should add, I had three highly experienced electrical engineers, also have a look at this problem, and none of them discovered it. When I later told them what the problem was they didn't believe it, until I demonstrated the problem and got them to remake the cables with soldered connections. Even today I still laugh about that one.
In my experience the quality of the connectors, and espescially the quality of the connection between the connector and cable, as well as obviously the quality of the connector-to-connector conection plays a far more significant role than the cable itself (provided the cable at least meets international standards).
A quick, cut to the chase story: A while ago I paid big bucks on some cables with BNC connectors. I spent 3 months trying to sort out what the problem was (I was having a problem). I finally discovered the crimped connectors were not good enough, that is the crimping was not adequate even though it passed the industry standards for crimping. I immediately cut the bnc connectors off and replaced them with bnc connectors that could be soldered. After that, problem solved. This is just one of many stories I could tell you about poor connections (and all of them were not obvious problems).
Edit:
I should add, I had three highly experienced electrical engineers, also have a look at this problem, and none of them discovered it. When I later told them what the problem was they didn't believe it, until I demonstrated the problem and got them to remake the cables with soldered connections. Even today I still laugh about that one.
Last edited:
Nice on XLRs, but
The oldest XLRs had rubber insulation; I might still have a couple in my spares box. With time, the rubber went hard, and its shock absorbing characteristics diminished. I still suspect this is where the "R" originated. They also made XLPs, with hard plastic.
Microphones always came out on males, and it was the convenience of having on type of cable as mic lead or extension that led to the generalisation of the female mic box. Certainla the Beeb (and a couple of other broadcast organisations) stuck to the more logical (for them) "it comes out of females and goes into males" philosophy, but all PA systems had their stage boxes/splitters as female in.
Soundcraft (very british) not only went for pin 3 hot in all their early consoles, they wired their output XLRs unbalanced, with a single bus wire connecting all the pin 1s and 2s in a straight line.
As pin one was specified ground, in all female XLRs (yes, even the strange six pole versions where the centre connection could confuse you) it was pushed forward so as to make contact first.
The oldest XLRs had rubber insulation; I might still have a couple in my spares box. With time, the rubber went hard, and its shock absorbing characteristics diminished. I still suspect this is where the "R" originated. They also made XLPs, with hard plastic.
Microphones always came out on males, and it was the convenience of having on type of cable as mic lead or extension that led to the generalisation of the female mic box. Certainla the Beeb (and a couple of other broadcast organisations) stuck to the more logical (for them) "it comes out of females and goes into males" philosophy, but all PA systems had their stage boxes/splitters as female in.
Soundcraft (very british) not only went for pin 3 hot in all their early consoles, they wired their output XLRs unbalanced, with a single bus wire connecting all the pin 1s and 2s in a straight line.
As pin one was specified ground, in all female XLRs (yes, even the strange six pole versions where the centre connection could confuse you) it was pushed forward so as to make contact first.
I totally AGREE.
...now go read my DIY cable thread and make THE BEST cables unknown to man. 😀
...BTW, I heard that an inferior cable is what lead to the meltdown at Fukushima...
There are many things that cables have been advertised for. Many explanations have been well known in technical documents. The issue is that there has been no research conducted to sort all this out in terms of magnitude of influence in a measureable way. While I have posted some measurements, I must say that to date I still hear a difference between various cable material that show not so much traceable difference in my measurements. What I have posted in only one of the measurement categories I find that can be measureably identified in association with listening differences.
If I terminate the cables with a 50Ohm terminator, then the whole impedance becomes flat to 50 Ohms.
Some people have reported differences with different solder too. I have not been able to detect it yet.
If I terminate the cables with a 50Ohm terminator, then the whole impedance becomes flat to 50 Ohms.
Some people have reported differences with different solder too. I have not been able to detect it yet.
Last edited:
No, you have not.
You have posted a couple of useless plots, just as SY told you.
I have also read lot's of such "useless plots" and learned much from them. So it just depends on one's capability to read and interpret.😉 Post something more useful, then we will know what is really useful.
So who want's to set a "useful" example without quoting others?
So who want's to set a "useful" example without quoting others?
George, what do the plots mean???? What is the vertical axis? What is the test setup? You're a very smart guy so I can't imagine that you expect anyone to extract anything or try to come up with meaningful measurements or analysis from some wavy lines with no scale or context. Hell, I don't even know if those are speaker cables, interconnects, electrical measurement, acoustic measurement... as you've presented them, they're wavy lines, no more, no less.
- Status
- Not open for further replies.