|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
108.249.169.177
I have a Audio Note transport feeding a Metrum Hex dac.
I have a Harmonix digital cable and an Analysis Plus digital cable. The both sound very nice and identical to each other. Just for the fun of it I tried a spare Grover Huffman analog interconnect. Totally different sound. Much more lively and engaging feeling. Faster transients. My question is is there a real difference between analog coaxial interconnects and digital coax cables?
Alan
Follow Ups:
how is your project coming along -Alan?
If your Hex is anything like my mark I Octave, then a sandbag on top may affect the sound more than a digital cable.
I big or heavy a sandbag?
Alan
I put cleaned "playground" sand (from Home Depot or wherever) in a Ziploc sandwich baggie (maybe some baggies are quart size?). Actually, I have my Octave sitting on a couple of these w/ one or two baggies on top. I have these sandbags all over my stereo, but where it makes the biggest difference is on the circuit board of my CJ preamp (w/ tubes) and then on the Octave.
The bass on my Octave is not right without sandbags (or more expensive damping systems may be good too).
I can hear differences between each cable I use for my SPDIF on various DACs over the years. I used to tune my digital sound that way.
I tried a long glass fiber on my Octave (Mark I) and it was clearly inferior to my old Transparent digital RCA.
My friend loves his Morrow digital cable; I'm not sure which model he got.
As others like Tony have pointed out, the characteristic impedance is the important parameter and that depends on the geometry and dielectric properties with respect to the wavelengths being transmitted.
According to the patent, the Huffman interconnects are optimised for LF "analogue signals" (up to 200kHz, although technically 30 to 300kHz) and the main point of the design is to achieve greater linearity. The patent does talk about the concept being applicable for Video transmission (HF) and SPDIF fits into the same bandwidth requirements (~10MHz) so it is distinctly possible that your interconnect will work "adequately" as in the receiver is able to decode the incoming data stream without glitching.
The fact that you are able to use the analogue interconnect successfully as a digital interconnect says more about the quality of your DIR than about any superiority (or otherwise) of the Huffman cable in this application. Depending on the design of the receiver circuit, the received clock is slaved to the jitter of the recovered clock. However, most modern designs will reclock the recovered clock with respect to a cleaner local clock thus making the system more immune to input jitter. Consequently, given your enthusiastic assessment of the sound using the Huffman cable, I doubt that your opinion would change even if I were in a position to prove that the Huffman cables were technically less suited compared to your other digital interconnects!
Are your cables two or three tubes in the sheath? If 3, the sheath will be triangular in shape. Basically the topology is NOT coaxial and the conductors are flat strips positioned in the centre of a cylinder (of an insulating material). I would be curious to see how these cables measure as you move up to VHF (and beyond). Huffman doesn't publish specifications on his website, so it would be interesting if he is able to provide any information regarding effective capacitance and the variation in characteristic impedance with frequency.
Regards Anthony
"Beauty is Truth, Truth Beauty.." Keats
Give The Cable Company (fatwyre.com) a ring. I would venture to say
there is very little in the way of cables that they "don't" carry !
Second note;
place a call to Galen Carol for additional information. He is the best!
Alan,
besides the 75 ohm resistance factor, another thing to consider, is that the Grover IC may provide a better synergy.
That is what i'm thinking. Now I have to go thru all my old interconnects to see if there is an even better synergy. Love this hobby
Alan
Bit unclear what you mean with audible frequencies.
A SPDIF doing 2 channel stereo at 44.1 kHz runs at 5.6 MHz.
The Well Tempered Computer
Yes, an analog cable doesn’t have a 75 Ohm AC resistance.
A true SPDIF cable (assuming this is what you are using) should be 75 Ohm
Analog cables causes an impedance mismatch, hence input jitter.
However, if the run is short, one might wonder if it is audible.
The Well Tempered Computer
The 75 ohm impedance is only good at rf frequencies. At audible frequencies the impedance is all over the place. Also rca connectors do not spec there connectors at all . Only bnc connectors are true 75 ohm and again only at rf frequencies
Alan
The relevant factor is the length of the cable vs. the wavelength of the signal. At audio frequencies the wavelength is long, e.g. ten's of kilometers. No problem for audio interconnects, but of interest to telephone companies. As Roseval pointed out, SPDIF operates at RF frequencies and cable lengths need to be extremely short before impedance doesn't matter.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Extremely short S/PDIF cables whose impedance is NOT properly controlled to 75 ohms can create signal reflections between source and DAC. These confuse the DAC's clock and cause clock jitter. The sonic result is a loss of focus and, well, timing.
If one has no idea whether impedance is controlled properly in any of source, cable and the DAC itself, it's best to go with a coax cable 1.5m long. This gives any reflections time to travel down the cable and back slowly enough that they arrive at the DAC offset from the true signal step.
The issue here is the rise time of the signal, with fast rise times involving much higher frequencies than the base signaling rate. However, the rise time is not infinite and the frequencies involved are limited. If the cable is sufficiently short then there won't be an issue, i.e. the cable will not have to be analyzed as a transmission line. If the cable is short enough, reflections from previous transitions will have died out as well. This means that there won't be audio signal dependent jitter.
A DAC that uses SPDIF must have some means to deal with jitter on its input, e.g. some kind of reclocking or clock cleaning, typically done with some combination of buffers and PLL(s). If it doesn't have this then the DAC is junk. If it does jitter on SPDIF will have at worst a second order effect on sound quality (e.g. residuals sneaking pass a PLL) or a tertiary effect (e.g. ground bounce on DAC clock circuitry cause by noise generated by the SPDIF receiver circuitry bypasses reclocking).
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Ok. I fully understand. But, If i'm using the Huffman audio cable has a digital cable doesn't that mean I am getting all kinds of reflectionsand cable induced jitter yet this cable sounds better to me than the digital cables. Is it possible that the Huffman analog cable has been designed more like a digital cable so it is near 75 ohms at rf frequencies yet would still sound fine as an analog cable? Huffman does make a digital cable. Sorry to be such a pest.
Alan
Post a Followup:
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: