Re: Re: 50ohm interconnect
Hi KP11520,
My post was referring To Mooly's post, not your's if that is what you mean in your last post.
The use of any wire/cable is basically fine for speaker cables. HOWEVER terminating speaker cable/wire at their ends with fixed resistors for impedance purposes is not good.
Again, I was not referring to your post.
Mooly said:
Hi KP11520,
My post was referring To Mooly's post, not your's if that is what you mean in your last post.
The use of any wire/cable is basically fine for speaker cables. HOWEVER terminating speaker cable/wire at their ends with fixed resistors for impedance purposes is not good.
Again, I was not referring to your post.
ACD said:I can say that for line level interconnections it makes a h*** of a difference
In full agreement. I am a big fan of low impedances/high currents; not so sure if the transmission line theory holds much water.
The high current concept can also be extended to volume pots: the highest value i use these days is 600ohm.
Hi,
Final post by me on this thread about Coax as speaker interconnects.
BC, if you send me a PM I will e-mail you some info.
Ordinary Coax, 50 ohm 75 ohm or any other impedance does not behave as a transmission line at low (audio) frequencies. It does however posses other characteristics that may ( or may not ) be beneficial in certain cases. Every audio system is unique in many ways, and it's what works for you that's important.
As always, Yer pays ya money, ya takes your choice
And no if anyone is wondering, I don't use Coax for any audio applications.
Final post by me on this thread about Coax as speaker interconnects.
BC, if you send me a PM I will e-mail you some info.
Ordinary Coax, 50 ohm 75 ohm or any other impedance does not behave as a transmission line at low (audio) frequencies. It does however posses other characteristics that may ( or may not ) be beneficial in certain cases. Every audio system is unique in many ways, and it's what works for you that's important.
As always, Yer pays ya money, ya takes your choice
And no if anyone is wondering, I don't use Coax for any audio applications.
Just to make it more clear;
Why do we make Amplifiers for audio, that can handle 1 MHz or more... That's very much more than the upper 20 KHz that's stated as our listening limit ?
Because audio ain't pure sine waves, but complex waves with very high rise time (well beyond the 20KHz).
Try listen to an amplifier with a 24 dB roll off at 20KHz.
It will sound like an transistor radio from the 60's
Why do we make Amplifiers for audio, that can handle 1 MHz or more... That's very much more than the upper 20 KHz that's stated as our listening limit ?
Because audio ain't pure sine waves, but complex waves with very high rise time (well beyond the 20KHz).
Try listen to an amplifier with a 24 dB roll off at 20KHz.
It will sound like an transistor radio from the 60's
ACD said:Hello lineup from the great north
I wouldn't promote my self and therefore didn't made a link to this, however now when you have pulled it all into public attention, I can say that for line level interconnections it makes a h*** of a difference
I did post some pictures in this thread
http://www.diyaudio.com/forums/showthread.php?s=&threadid=96192&perpage=50&highlight=&pagenumber=7 some times ago. I have attached the picture here again.
However I have never tried Coax as speaker cables.....
Maybe I should give it a try
Yeah, I know.
And you are too much of gentleman, to plug your stuff.
Not all are, for sure
Some thinking of your buffer. And the use of it:
1. I would say when we have very short audio cables,
to and from Preamplifier (our topic here)
say 0.5 - 1.5 meter, it is not often a problem
to use good quality audio interconect cable (not coax). And without any buffering.
And especially if we have not very low level signal, like from turntable,
and we have not receiving end Too high impedance ( like > 100kohm)
2. The beauty of such a 50 Ohm output buffer + fixed 50 Ohm impedance coax, terminated with 50 Ohm
is that that it works Every situation at very high quality
for transfer of audio signals between audio units!
95% of cases you do not have to worry about anything
Aslo excellent for taking signal from a microphone setup.
Very Low level signals!
3. Think of this case:
you want to have an audio signal present in another room, in another floor in your house.
But signal source is located in another place, like your hifi turntable.
You may need 5 - 20 meter cable.
Here such a buffer you suggest/provide is a near to 'perfect' solution.
4. Here comes my question/suggestion:
Weblink:
GRADO - world's finest HeadPhones - Product List
I would say, with those very good specs of your buffer,
it may, for some 32 Ohms hifi HeadPhones,
make a perfect HP-amp.
We have some Hifi GRADO that are in the lower impedance end.
(sennheiser would not match as good, as they are often 300 Ohm)
Regards, lineup
From post 1
When I build mono block amps, then it's because I want to place the amps near the speakers, with long interconnect cables between preamp and power amp like in jerryo's question.
lineup;
Thanks
Answer to your questions:
1. It do make an improvement even on short interconnect cables.
2+3. Yes indeed.
4. Yes I have. You can give the buffer any output impedance you like, to match your headphones. Max output for the standard buffer is app. +/-2 Volts lower than the rail supply, with a maximum of +/-13 Volt out.
When I build mono block amps, then it's because I want to place the amps near the speakers, with long interconnect cables between preamp and power amp like in jerryo's question.
lineup;
Thanks
Answer to your questions:
1. It do make an improvement even on short interconnect cables.
2+3. Yes indeed.
4. Yes I have. You can give the buffer any output impedance you like, to match your headphones. Max output for the standard buffer is app. +/-2 Volts lower than the rail supply, with a maximum of +/-13 Volt out.
Thank you Jan for bringing us back to my original question; it all comes down to the way music signals are passed through cables. My initial question was based on whether it is more beneficial to drive a line level signal through a longer and smaller cable than to drive a power amplified signal through a longer and larger cable. To a degree I guess it depends on what sort of power you are dealing with. I am using a pair of Linn Isobariks which are very power hungry and would require quite substantial speakers cables (which my wife does not like) to do them justice. I think the suggestions from Jan are excellent so I will use his "buffer" (from Danish Audio Innovation) and build a simple pre-amp based on them. I just need to find a suitable remote volume control kit to go with it. Anyone had any experience with the remote volume kits available from the ebay shop DIY Gene. The price seems to good to be true. Cheers everyone.
Hi,
Re my post #27. and post #29 Sorry but I have to ask, where does the 24db down at 20khz come from ?
I do have an open mind on the effects of audio above the notional 20k upper limit, but unfortunately have no source equipment that will exceed this by any significant degree, let alone speakers that will reproduce it.
If I have remembered my theory, that wavelength is 300000/f ( f in kilohertz) the wavelength of a 20 hz signal is some 15000km, and at 20khz it is 15km and at 1mhz some 300 metres. A short length of cable can't function as a transmission line under these conditions, certainly not 50 ohm coax terminated with a speaker. Nowhere have I implied that they do. It is the cables properties of self inductance self capacitance and resistance that come into play at low frequencies. If you want low inductance cables, coax is the one to go for.
Regards Karl
Re my post #27.
and post #29 Sorry but I have to ask, where does the 24db down at 20khz come from ?I do have an open mind on the effects of audio above the notional 20k upper limit, but unfortunately have no source equipment that will exceed this by any significant degree, let alone speakers that will reproduce it.
If I have remembered my theory, that wavelength is 300000/f ( f in kilohertz) the wavelength of a 20 hz signal is some 15000km, and at 20khz it is 15km and at 1mhz some 300 metres. A short length of cable can't function as a transmission line under these conditions, certainly not 50 ohm coax terminated with a speaker. Nowhere have I implied that they do. It is the cables properties of self inductance self capacitance and resistance that come into play at low frequencies. If you want low inductance cables, coax is the one to go for.
Regards Karl
Mooly;
The 24dB roll off was just an example.....
If you make an amplifier with 24dB filter that rolls off from 20 KHz and up, your amp wouldn't sound very good and try feed it with a pure square wave, the output will be quite different than the input.
All this is about obtaining maximum rise-time (V/uS).
In complex audio signals you can easily have waves that requires faster rise time than 50uS (as for 20 KHz).
For example to reproduce a 100KHz square wave, the rise time is 1uS from peak to peak. And 1nS for 1MHz.
The 24dB roll off was just an example.....
If you make an amplifier with 24dB filter that rolls off from 20 KHz and up, your amp wouldn't sound very good and try feed it with a pure square wave, the output will be quite different than the input.
All this is about obtaining maximum rise-time (V/uS).
In complex audio signals you can easily have waves that requires faster rise time than 50uS (as for 20 KHz).
For example to reproduce a 100KHz square wave, the rise time is 1uS from peak to peak. And 1nS for 1MHz.
Hi Jan,
I asked , because the two posts together read a little bit as if you were saying that coax as a speaker cable would cause this massive loss in H.F. which of course it won't.
Your point on rise times I agree with ( maybe not quite going up to 1Mhz bandwidth for audio ), but yes absolutely. Square wave testing is a vital part of the design process.
Regards Karl
I asked
, because the two posts together read a little bit as if you were saying that coax as a speaker cable would cause this massive loss in H.F. which of course it won't. Your point on rise times I agree with ( maybe not quite going up to 1Mhz bandwidth for audio
), but yes absolutely. Square wave testing is a vital part of the design process.Regards Karl
FWIW, when I was a kid I could just barely maybe hear the difference when the 15kHz (?) filter of my old Dynaco preamp was switched in. I did have hearing response to 20kHz. I think the filter was to knock out FM something or other. Today my hearing isn't terrible, but I can't hear any filtration at 20kHz, nor any effect of anything I add at ultrasonic frequencies. I could switch in 100dB of filtration at 24kHz, as long as it didn't ripple the passband, and it wouldn't make a bit of difference. I think the various arguments about ultrasonics are an extremely minor effect, if valid at all.
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